EPIRUS Biopharmaceuticals (EPRSQ) 10-K 31 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 27, 2015	Jun. 30, 2014
Property and Equipment, Net.
Entity Registrant Name	EPIRUS Biopharmaceuticals, Inc.
Entity Central Index Key	1135906
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		23,514,851
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Entity Public Float			$31,690,541.88

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$21,462	$1,798
Prepaid expenses and other current assets	1,556	888
Total current assets	23,018	2,686
Property and equipment, net	704	90
In-process research and development	5,500	2,437
Intangible assets, net	3,605
Goodwill	16,363	1,499
Restricted cash	1,825	25
Other assets	374	57
Total assets	51,389	6,794
Current liabilities:
Accounts payable	2,483	1,067
Accrued expenses	4,101	2,492
Deferred revenue	50
Other current liabilities	557
Convertible notes		12,500
Deferred tax benefit	185	185
Total current liabilities	7,376	16,244
Long term debt, net of debt discount	7,282
Warrant liability		5,843
Deferred revenue, net of current portion	946
Deferred tax liability	2,166
Deferred tax benefit, net of current portion	553	738
Other non-current liabilities	665
Commitments and contingencies (Note 15)
Stockholders' equity (deficit):
Preferred stock, $0.001 par value; Authorized-5,000,000 shares; Issued and Outstanding -0 shares at December 31 2014 and 2013
Common stock, $0.001 par value; Authorized-- 300,000,000 shares; Issued--12,934,102 and 237,026 shares at December 31, 2014 and December 31, 2013, respectively; Outstanding--12,920,843 and 237,026 shares at December 31, 2014 and December 31, 2013, respectively	13
Additional paid-in capital	118,959	5,348
Accumulated deficit	-86,571	-44,727
Total stockholders' equity (deficit)	32,401	-39,379
Total liabilities, convertible preferred stock and stockholders' equity	51,389	6,794
Series A Convertible Preferred Stock
Current liabilities:
Series A convertible preferred stock, $0.0001 par value; Authorized--0 and 55,653,728 shares at December 31, 2014 and December 31, 2013; Issued and Outstanding--0 and 27,248,746 shares at December 31, 2014 and December 31, 2013, respectively; aggregate liquidation preference of $0 and $27,249 at December 31, 2014 and December 31, 2013, respectively		$23,348

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Preferred stock (par value)	$0.00	$0.00
Preferred stock - shares authorized	5,000,000	5,000,000
Preferred stock - shares issued	0	0
Preferred stock - shares outstanding	0	0
Common stock (par value)	$0.00	$0.00
Common stock - shares authorized	300,000,000	300,000,000
Common stock - shares issued	934,102	237,026
Common stock - shares outstanding	920,843	237,026
Series A Convertible Preferred Stock
Convertible preferred stock (par value)	$0.00	$0.00
Convertible preferred stock - shares authorized	0	55,653,728
Convertible preferred stock - shares issued	0	27,248,746
Convertible preferred stock - shares outstanding	0	27,248,746
Convertible preferred stock aggregate liquidation preference	$0	$27,249

Consolidated_Statements_of_Ope

Consolidated Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Revenue	$4
Operating expenses:
Research and development	16,286	9,659
General and administrative	22,973	4,809
Total operating expenses	39,259	14,468
Loss from operations	-39,255	-14,468
Other income (expense):
Interest expense, net	-2,672	-5,543
Change in fair value of warrant liability	-222	-789
Other income (expense), net	262	5
Total other income (expense), net	-2,632	-6,327
Loss before income taxes	-41,887	-20,795
Benefit (loss) from income taxes	43
Net loss	-41,844	-20,795
Net loss per share - basic and diluted	($6.81)	($88.26)
Weighted average number of common shares used in net loss per share calculation--basic and diluted	6,141,605	235,603
Comprehensive loss	($41,844)	($20,795)

Statements_of_Changes_in_Stock

Statements of Changes in Stockholders' Equity (USD $)	Hercules Notes	Hercules Notes	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common stock	Additional Paid-in Capital	Accumulated Deficit	Total
In Thousands, except Share data, unless otherwise specified	Additional Paid-in Capital
Balance at beginning of the period at Dec. 31, 2012						$2,745	($23,932)	($21,187)
Balance at beginning of the period at Dec. 31, 2012			22,844
Balance at beginning of the period (in shares) at Dec. 31, 2012			26,750,540
Balance at beginning of the period (in shares) at Dec. 31, 2012					210,586
Increase (Decrease) in Convertible Preferred Stock
Exercise of preferred stock warrant			504
Exercise of preferred stock warrant (in shares)			498,306
Exercise of common stock warrant						2		2
Exercise of common stock warrant ( in Shares)					2,836
Exercise of stock options						21		21
Exercise of stock options (in shares)					23,604
Beneficial conversion feature						2,440		2,440
Stock-based compensation expense and vesting of restricted stock						140		140
Net loss							-20,795	-20,795
Balance at end of the period at Dec. 31, 2013						5,348	-44,727	-39,379
Balance at end of the period at Dec. 31, 2013			23,348
Balance at end of the period (in shares) at Dec. 31, 2013			27,248,746
Balance at end of the period (in shares) at Dec. 31, 2013					237,026			237,026
Increase (Decrease) in Convertible Preferred Stock
Exercise of preferred stock warrant			6,436	993
Exercise of preferred stock warrant (in shares)			5,101,816	787,402
Exercise of stock options						90		90
Exercise of stock options (in shares)					98,405
Issuance of preferred stock			13,184	30,478
Issuance of preferred stock ( in shares)			13,184,383	24,409,444
Issuance of convertible notes						2,071		2,071
Extinguishment of convertible notes				5,013		-1,150		-1,150
Extinguishment of convertible notes (in shares)				3,947,363
Exchange of preferred stock for common stock			-42,968	-36,484	10	79,442		79,452
Exchange of preferred stock for common stock ( in shares)			-45,534,945	-29,144,209	9,901,700
Issuance of common stock in connection with the Merger					3	31,321		31,324
Issuance of common stock in connection with the Merger ( in shares)					2,610,871
Exchange of warrants in connection with the Merger	248	248				167		167
Issuance of common stock upon vesting of restricted stock units						-297		-297
Issuance of common stock upon vesting of restricted stock units ( in shares)					27,540
Stock-based compensation expense and vesting of restricted stock						1,719		1,719
Stock-based compensation expense and vesting of restricted stock ( in shares)					45,301
Net loss							-41,844	-41,844
Balance at end of the period at Dec. 31, 2014					$13	$118,959	($86,571)	$32,401
Balance at end of the period (in shares) at Dec. 31, 2014			0
Balance at end of the period (in shares) at Dec. 31, 2014					12,920,843			920,843

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	($41,844)	($20,795)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	165	31
Non-cash interest expense	2,475	4,912
Stock-based compensation and vesting of restricted stock	1,719	140
Extinguishment of convertible notes	-22
Deferred rent and lease incentive activity	95
Deferred taxes	-185	-16
Change in fair value of warrants	222	789
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	-276	-60
Restricted cash	50
Other non-current assets	-304	-52
Accounts payable	-174	462
Accrued expenses and other current liabilities	1,823	1,711
Other non-current liabilities	-210
Deferred revenue	996
Net cash used in operating activities	-35,470	-12,878
Cash flows from investing activities:
Cash acquired in acquisition	13,756
Purchases of property and equipment	-217	-86
Proceeds from the sale of property & equipment	4
Additions to intangible assets	-1,250
Net cash provided by (used) in investing activities	12,293	-86
Cash flows from financing activities
Proceeds from the issuance of preferred stock and warrants	30,478
Proceeds from the issuance of convertible notes	5,000	12,500
Proceeds from the issuance of debt, net of fees paid to lender	7,285
Payment of debt issuance costs	49
Proceeds from the exercise of preferred stock warrants	334	5
Proceeds from the exercise of common stock warrants		2
Repurchases of common stock	-297
Proceeds from the exercise of common stock options	90	21
Net cash provided by financing activities	42,841	12,528
Net increase (decrease) in cash and cash equivalents	19,664	-436
Cash and cash equivalents - Beginning of period	1,798	2,234
Cash and cash equivalents - End of period	21,462	1,798
Supplemental disclosure of cash flow information
Cash paid for interest	101
Cash paid for income taxes	177
Supplemental schedule of non-cash investing and financing activities:
Amount in accounts payable for capital expenditure	5
Conversion of convertible debt and accrued interest into preferred stock and warrants	13,184
Extinguishment of convertible debt and accrued interest into preferred stock	5,013
Exercise of warrants into preferred stock	7,095	499
Conversion of preferred stock into common stock	79,452
Conversion of preferred stock warrants to equity	167
Issuance of warrants in connection with Hercules debt	248
Leasehold improvements incurred by Landlord	477
Fair value of assets and liabilities acquired in the Merger
Fair value of assets acquired in Merger	36,223
Fair value of liabilities assumed in Merger	-4,899
Fair value of net assets acquired in Merger	$31,324

Organization

Organization	12 Months Ended
	Dec. 31, 2014
Organization
Organization	1. Organization
	On July 15, 2014, EPIRUS Biopharmaceuticals, Inc., a Delaware corporation and private company ("Private Epirus"), completed its merger with EB Sub, Inc., a wholly-owned subsidiary of Zalicus Inc., a Delaware corporation ("Zalicus"), pursuant to the terms of that certain Agreement and Plan of Merger and Reorganization (as amended, the "Merger Agreement"), dated as of April 15, 2014, by and among Private Epirus, Zalicus and EB Sub, Inc., formerly known as BRunning, Inc. (the "Merger"). As part of the Merger, Zalicus was renamed EPIRUS Biopharmaceuticals, Inc. ("Public Epirus") and Private Epirus was renamed EB Sub, Inc. ("EB Sub"). The boards of directors of Private Epirus and Zalicus approved the Merger on April 15, 2014, and the stockholders of Private Epirus and Zalicus approved the Merger and related matters on July 15, 2014. Following completion of the Merger, EB Sub, Inc. (formerly Private Epirus), is the surviving corporation of the Merger and a wholly-owned subsidiary of Public Epirus.
	The term "Company" as used in these notes to consolidated financial statements refers to Private Epirus and its subsidiaries prior to the completion of the Merger and to Public Epirus and its subsidiaries subsequent to the completion of the Merger.
	Prior to the Merger, Zalicus was a biopharmaceutical company developing drug candidates with a focus on the treatment of pain. Following the merger, Public Epirus became a commercial-stage biopharmaceutical company focused on improving patient access to important biopharmaceuticals by developing, manufacturing, and commercializing biosimilar therapeutics, or biosimilars, in targeted geographies worldwide. The Company has a principal place of business in Boston, Massachusetts. The Company seeks to build a sustainable, profitable biosimilar company with a pipeline of operationally synergistic monoclonal antibodies in inflammation and immunology.
	The Company's lead product candidate is BOW015, a biosimilar version of Remicade® (infliximab). Remicade, marketed by Johnson & Johnson, Merck Schering and Mitsubishi Tanabe for the treatment of various inflammatory diseases.
	In November 2014, the Company launched BOW015 in India, under the brand name InfimabTM, the first infliximab biosimilar in India, with its commercialization partner Ranbaxy Laboratories Limited ("Ranbaxy"). The Company expects to utilize its existing regulatory data package to gain regulatory approval for BOW015 in additional countries.
	The Company's pipeline of biosimilar product candidates also includes BOW050, a biosimilar version of Humira® (adalimumab), which is marketed by AbbVie and used to treat inflammatory diseases, and BOW070, a biosimilar version of Actemra® (tocilizumab), which is marketed by Genentech/Roche and used to treat inflammatory diseases. BOW050 and BOW070 are in preclinical development.
	In August 2013, the Company transferred all of its intellectual property to its subsidiary, Epirus Switzerland GmbH, a Swiss corporation. As compensation for this transaction, the Company entered into a promissory note with Epirus Switzerland GmbH in the amount of $10,080, which is eliminated within the consolidated financial statements.
	To date, the Company has devoted substantially all of its efforts to product research and development market research, and raising capital. The Company is subject to a number of risks similar to those of other development stage life science companies, including dependence on key individuals, competition from other companies, the need for development of commercially viable products, and the need to obtain adequate additional financing to fund the development of its product candidates. The Company is also subject to a number of risks similar to other companies in the industry, including rapid technological change, regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability, and dependence on key individuals. If the Company does not successfully commercialize any of its product candidates within India or in additional countries, it will be unable to generate recurring product revenue or achieve profitability. As presented in the financial statements, at December 31, 2014, the Company had cash and cash equivalents of $21,462 and an accumulated deficit of $86,571. During the year ended December 31, 2014, the Company incurred a net loss of $41,844. The Company believes that its existing cash and cash equivalents along with the aggregate net proceeds of $47,955 from its equity offering in February 2015 and $7,500 in proceeds currently available from the second tranche of its debt financing will be sufficient to fund its current operating plan and capital expenditure requirements into the third quarter of 2016.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies
	Basis of Presentation and Use of Estimates
	The preparation of the Company's consolidated financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company's consolidated financial statements and accompanying notes. The most significant estimates in the Company's consolidated financial statements relate to the valuation of equity awards, fair value estimates of warrant liabilities, embedded derivatives, purchase price allocations including fair value estimates of intangible assets, estimated useful lives of fixed assets and intangible assets and accruals relating to clinical trials. The Company bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis. The Company's actual results may differ from these estimates under different assumptions or conditions.
	Prior to becoming a public company through the Merger, the Company utilized significant estimates and assumptions in determining the fair value of its common stock. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
	The Company utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation (Practice Aid), to estimate the fair value of its common stock. The methodologies included the probability-weighted expected return method ("PWERM") and option-pricing method ("OPM"). Each valuation methodology included estimates and assumptions that required the Company's judgment. These estimates included assumptions regarding future performance, including the successful completion of preclinical studies and clinical trials and the time to completing an IPO or sale. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
	Principles of Consolidation
	The consolidated financial statements include the accounts of Epirus and its wholly owned subsidiaries: EB Sub, Inc., a Delaware Corporation, Epirus Biopharmaceuticals Ltd., a United Kingdom corporation, Epirus Switzerland GmbH, a Swiss corporation, Epirus Brasil Tecnologia Ltda, a Brazilian corporation and Zalicus Pharmaceuticals Ltd., a Canadian corporation. All significant intercompany balances and transactions have been eliminated in consolidation.
	Merger and Exchange Ratio
	The Merger has been accounted for as a "reverse merger" under the acquisition method of accounting for business combinations with Private Epirus treated as the accounting acquirer of Zalicus. The historical financial statements of Private Epirus have become the historical financial statements of Public Epirus, or the combined company, and are included in this filing labeled Epirus Biopharmaceuticals, Inc. As a result of the Merger, historical common stock, stock options and additional paid-in capital, including share and per share amounts, have been retroactively adjusted to reflect the equity structure of Public Epirus, including the effect of the Merger exchange ratio and the Public Epirus common stock par value of $0.001 per share. See Note 4, "Merger," for additional discussion of the Merger and the exchange ratio.
	Reverse Stock Split
	On July 16, 2014, Public Epirus effected a 1-for-10 reverse stock split of its outstanding common stock, par value $0.001 per share ("Public Epirus Common Stock") (the "Reverse Stock Split"). The accompanying consolidated financial statements and these notes to consolidated financial statements, including the Merger exchange ratio (Note 4) applied to historical Private Epirus common stock and stock options, give retroactive effect to the Reverse Stock Split for all periods presented. The shares of Public Epirus Common Stock retained a par value of $0.001 per share.
	Segment and Geographic Information
	Operating segments are defined as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker ("CODM") or decision-making group in making decisions regarding resource allocation and assessing performance. The Company and the Company's CODM view the Company's operations and manage its business in one operating segment: the development and commercialization of biosimilar monoclonal antibodies for emerging markets. The Company's entire business is managed by a single management team, which reports to the Chief Executive Officer. As of December 31, 2014 and 2013, all of the Company's long-lived assets were held within the United States and Switzerland.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with maturities of 90 days or less from the date of purchase to be cash equivalents. As of December 31, 2014 and 2013, all cash and cash equivalents are held in depository accounts at commercial banks. Cash equivalents are reported at fair value.
	Concentrations of Credit Risk and Off-Balance Sheet Risk
	Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and restricted cash. The Company maintains its cash and cash equivalent balances in the form of checking and savings accounts with financial institutions that management believes are creditworthy. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company has no financial instruments with off-balance-sheet risk of loss.
	Fair Value of Financial Instruments
	The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The Company determines the fair market values of its financial instruments based on the fair value hierarchy, which is a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the financial instrument based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the financial instrument and are developed based on the information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported or disclosed fair value of the financial instruments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy, and its applicability to the Company's financial assets and liabilities, are described below:
	Level 1 Inputs:    Unadjusted quoted prices in active markets that are accessible at the measurement date of identical, unrestricted assets and liabilities.
	Level 2 Inputs:    Quoted prices for similar assets and liabilities, or inputs that are observable, either directly or indirectly, for substantially the full term through corroboration with observable market data. Level 2 includes investments valued at quoted prices adjusted for legal or contractual restrictions specific to the security.
	Level 3 Inputs:    Pricing inputs are unobservable for the assets and liabilities, that is, inputs that reflect the reporting entity's own assumptions about the assumptions market participants would use in pricing the assets. Level 3 includes private investments that are supported by little or no market activity.
	The fair value hierarchy level is determined by asset class based on the lowest level of significant input. In periods of market inactivity, the observability of prices and inputs may be reduced for certain instruments. This condition could cause an instrument to be reclassified between levels. During the year ended December 31, 2014 and 2013, there were no transfers between levels.
	The Company measures cash equivalents at fair value on a recurring basis. The fair value of cash equivalents is determined based on "Level 1" inputs, which consist of quoted prices in active markets for identical assets. The fair value of the warrant liability was determined based on "Level 3" inputs and utilizing the Black-Scholes option-pricing model (Note 11).
	The fair value of the Company's note is determined using current applicable rates for similar instruments with similar settlement features as of the balance sheet date. The carrying value of the Company's long term debt approximates its fair value as the Company's interest rate is near current market rates for instruments with similar settlement features. The fair value of the Company's note was determined using Level 3 inputs.
	Property and Equipment
	Property and equipment consists of office furniture, office and computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Property and equipment are recorded at cost and are depreciated when placed into service using the straight-line method of depreciation, based on their estimated useful lives as follows:
	Asset Description	Estimated Useful Lives
	Furniture and fixtures	5 years
	Office and computer equipment	3 years
	Leasehold improvements	Shorter of the useful life or remaining lease term
	Upon retirement or sale, the cost of assets disposed and the related accumulated depreciation is removed from the accounts and any resulting gain or loss is recorded in the consolidated statements of operations.
	The Company evaluates the potential of its long-lived assets for impairment if events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful life of the assets is no longer appropriate. The impairment test is based on a comparison of the undiscounted cash flows expected to be generated from the use of the asset group and its eventual disposition to the carrying value of the asset group. If impairment is indicated, the assets are written down by the amount by which the carrying value of the assets exceeds the related fair value of the assets. Any write-downs are treated as permanent reductions in the carrying value of the assets. No such impairment losses have been recorded through December 31, 2014.
	Restricted Cash
	Restricted cash represents cash held in depository accounts at financial institutions to collateralize a conditional stand-by letter of credit related to the Company's Boston, Massachusetts, facility lease agreement and the Company's subleased Cambridge, Massachusetts facility. Restricted cash is reported as non-current unless the restrictions are expected to be released in the next 12 months.
	In-process Research & Development
	In-process research & development ("IPR&D") represents the fair value assigned to research and development assets that were not fully developed at the date of acquisition. IPR&D acquired in a business combination or recognized from the application of push-down accounting is capitalized on the Company's consolidated balance sheet at its acquisition-date fair value. Until the project is completed, the assets are accounted for as indefinite-lived intangible assets and subject to impairment testing. Upon completion of a project, the carrying value of the related IPR&D is reclassified to intangible assets and is amortized over the estimated useful life of the asset.
	When performing the impairment assessment, the Company first assesses qualitative factors to determine whether it is necessary to recalculate the fair value of its acquired IPR&D. If the Company determines, as a result of the qualitative assessment, that it is more likely than not that the fair value of acquired IPR&D is less than its carrying amount, it calculates the asset's fair value. If the carrying value of the Company's acquired IPR&D exceeds its fair value, then the intangible asset is written down to its fair value. For the year ended December 31, 2014 and 2013, the Company determined that there was no impairment of its IPR&D.
	Intangible Assets
	The Company amortizes its intangible assets using the straight-line method over its estimated economic life, which is approximately 16.5 years. The Company evaluates the potential impairment of its intangible assets if events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful life of the assets is no longer appropriate. The impairment test is based on a comparison of the undiscounted cash flows expected to be generated from the use of the asset group and its eventual disposition to the carrying value of the asset group. If impairment is indicated, the assets are written down by the amount by which the carrying value of the assets exceeds the related fair value of the assets. Any write-downs are treated as permanent reductions in the carrying value of the assets. For the year ended December 31, 2014 and 2013, the Company determined that there was no impairment of its intangible assets.
	Goodwill
	Goodwill represents the difference between the consideration transferred and the fair value of the net assets acquired under the acquisition method of accounting for push-down accounting. Goodwill is not amortized but is evaluated for impairment within the Company's single reporting unit on an annual basis, during the fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of the Company's reporting unit below its carrying amount. When performing the impairment assessment, the accounting standard for testing goodwill for impairment permits a company to first assess the qualitative factors to determine whether the existence of events and circumstances indicates that it is more likely than not that the goodwill is impaired. If the Company believes, as a result of the qualitative assessment, that it is more likely than not that the fair value of goodwill is impaired, the Company must perform the first step of the goodwill impairment test. The Company has determined that goodwill was not impaired as of December 31, 2014 and 2013. To date, the Company has not recognized any impairment charges related to goodwill.
	Revenue Recognition
	Multiple-Element Arrangements
	Under the authoritative guidance for revenue recognition related to multiple-element revenue arrangements, each deliverable within a multiple-element revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control. The Company considers a deliverable to have standalone value if the Company sells this item separately or if the item is sold by another vendor or could be resold by the customer. Deliverables not meeting the criteria for being a separate unit of accounting are accounted for on a combined basis.
	In the event the Company enters into a contract in which the deliverables are required to be separated, the Company will allocate arrangement consideration to each deliverable in an arrangement based on its relative selling price. The Company determines selling price using vendor-specific objective evidence ("VSOE"), if it exists; otherwise, the Company uses third-party evidence ("TPE"). If neither VSOE nor TPE of selling price exists for a deliverable, the Company uses estimated selling price ("ESP") to allocate the arrangement consideration. The Company applies appropriate revenue recognition guidance to each unit of accounting.
	Milestones
	Contingent consideration from research and development activities that is earned upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. At the inception of each arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive. This evaluation includes an assessment of whether: (a) the consideration is commensurate with either (1) the entity's performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity's performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
	Royalty Revenue
	Under certain license agreements to which the Company is a party, the Company receives royalty payments based upon its licensees' net sales of products. Generally, under these agreements, the Company receives royalty payments from licensees approximately one quarter in arrears after the licensee has sold the income generating product or products. The Company recognizes royalty revenues when it can reliably estimate such amounts and collectability is reasonably assured. As such, the Company generally recognizes royalty revenues in the quarter reported to it by its licensees. Therefore, royalty revenues are recognized one quarter in arrears from the quarter in which sales by its licensees occurred. Under this accounting policy, the royalty revenues the Company recognizes are not based upon estimates and are typically reported in the same period in which the Company receives payment from its licensees.
	Deferred Revenue
	Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized within 12 months from the balance sheet date are classified as long-term deferred revenue.
	Deferred Rent
	Deferred rent, included within other non-current liabilities, net of the current portion recorded in accrued expenses in the consolidated balance sheet, consists of the difference between cash payments and the recognition of rent expense on a straight-line basis for the facilities the Company occupies. The Company's lease for its Boston, Massachusetts, facility provides for a rent-free period as well as fixed increases in minimum annual rental payments. The total amount of rental payments due over the lease term is being charged to rent expense ratably over the life of the lease.
	Other Liabilities
	In conjunction with the Merger, as discussed in Note 4, the Company assumed a sublease liability for Zalicus' Cambridge, Massachusetts facility, which is included within other non-current liabilities, net of the current portion recorded in other current liabilities on the consolidated balance sheet. The liability represents the fair value of the difference between the total sublease payments to be received by the Company and the total payment obligation for the Company per the lease agreement.
	The Company has an operating lease for office space in Boston, Massachusetts. In connection with this lease, the Company and its third party lessor agreed that the lessor would pay for certain leasehold improvements on behalf of the Company. These leasehold improvements are accounted for as a lease incentive obligation, which is recorded in other non-current liabilities, net of the current portion recorded in other current liabilities. This liability is being amortized over the life of the lease and as a reduction to rent expense.
	Organizational Costs
	All organizational costs are expensed as incurred.
	Research and Development Costs
	Research and development costs are charged to expense as incurred in performing research and development activities. The costs include employee compensation, facilities and overhead, clinical study and related clinical manufacturing costs, regulatory and other related costs. Nonrefundable advanced payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.
	Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be.
	Stock-Based Compensation
	The Company accounts for grants of stock options and restricted stock based on their grant date fair value and recognizes compensation expense over the award's vesting period. The Company estimates the fair value of stock options as of the date of grant using the Black-Scholes option-pricing model and restricted stock based on the fair value of the underlying common stock, which is determined as the closing trading price of the Company's common stock subsequent to the Merger, in which the Company's common stock became publicly traded, and was determined by management prior to the Merger (Note 13).
Stock-based compensation expense represents the cost of the grant date fair value of employee stock option grants recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis, net of estimated forfeitures. The expense is adjusted for actual forfeitures at the end of each reporting period. Stock-based compensation expense recognized in the consolidated financial statements is based on awards that are ultimately expected to vest.
Stock-based awards issued to nonemployees are accounted for based on the fair value of such services received or of the equity instruments issued, whichever is more reliably measured. Awards are revalued at each reporting date and upon vesting and are expensed on a straight-line basis over the vesting period.
Income Taxes
The Company accounts for income taxes under the liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in operations in the period that includes the enactment date.
The Company recognizes net deferred tax assets through the recording of a valuation allowance to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future, in excess of its net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.
The Company records uncertain tax positions on the basis of a two-step process whereby: (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Net Loss Per Share
Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. During periods of income, the Company allocates participating securities a proportional share of income determined by dividing total weighted average participating securities by the sum of the total weighted average common shares and participating securities (the "two-class method"). The Company's convertible preferred stock, which was exchanged for Public Epirus Common Stock in the Merger, participated in any dividends declared by the Company and were therefore considered to be participating securities. Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods of loss, the Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. Diluted net loss per share attributable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, common stock equivalents have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented.
Comprehensive Loss
Comprehensive loss is the change in equity of a company during a period from transactions and other events and circumstances, excluding transactions resulting from investments by owners and distributions to owners. The Company's net loss equals comprehensive loss for all periods presented.
Recent Accounting Pronouncements
Revenue Recognition
In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in Accounting Standards Codification Topic 605, Revenue Recognition, and creates a new Topic 606, Revenue from Contracts with Customers. This guidance is effective for fiscal years beginning after December 15, 2016, with early adoption not permitted. Two adoption methods are permitted: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. The Company has not yet determined which adoption method it will utilize or the effect that the adoption of this guidance will have on its consolidated financial statements.
Discontinued Operations and Disposals
In April 2014, the FASB issued ASU No. 2014-8, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-8"). ASU 2014-8 changes the criteria for determining which disposals can be presented as discontinued operations and modifies related disclosure requirements. Under the new guidance, a discontinued operation is defined as a disposal of a component or group of components that is disposed of or is classified as held for sale and represents a strategic shift that has a major effect on an entity's operations and financial results. This accounting guidance applies prospectively to new disposals and new classifications of disposal groups as held for sale. The guidance is effective for fiscal years beginning after December 15, 2014.
Development Stage Entity
In June 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation ("ASU 2014-10"). ASU 2014-10 removes all incremental financial reporting requirements from GAAP for development stage entities, including the removal of Topic 915 from the FASB Accounting Standards Codification ("ASC"). In addition, the update adds an example disclosure in Risks and Uncertainties, ASC Topic 275, to illustrate one way that an entity that has not begun planned principal operations could provide information about the risks and uncertainties related to the company's current activities and removes an exception provided to development stage entities in Consolidations, ASC Topic 810, for determining whether an entity is a variable interest entity—which may change the consolidation analysis, consolidation decision, and disclosure requirements for a company that has an interest in a company in the development stage. ASU 2014-10 is effective for fiscal years beginning after December 15, 2014 with the revised consolidation standards effective for fiscal years beginning after December 15, 2016. Early adoption is permitted. The Company early adopted the guidance and eliminated the presentation and disclosure requirements of ASC Topic 915 during the three months ending June 30, 2014 and the year ended December 31, 2014.
Going Concern
In August 2014, the FASB issued ASC Update No. 2014-15, Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern (Subtopic 205-40) ("ASU 2014-14"). ASU 2014-15 requires management to assess an entity's ability to continue as a going concern every reporting period, and provide certain disclosures if management has substantial doubt about the entities ability to operate as a going concern, or an express statement if not, by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The adoption of ASU 2014-15 is not expected to have an impact on the Company's financial position or results of operations.

Business_Agreements

Business Agreements	12 Months Ended
	Dec. 31, 2014
Business Agreements
Business Agreements	3. Business Agreements
	Ranbaxy Laboratories
	In January 2014, the Company and Ranbaxy Laboratories Limited ("Ranbaxy") executed a royalty-bearing and non-transferrable license agreement ("License Agreement") for BOW015 to Ranbaxy for a broad range of territories including India, selected Southeast Asian markets and North Africa. Under the terms of the agreement, the Company and Ranbaxy will pursue the commercialization of BOW015 in India and Ranbaxy received the right to sell BOW015 in the territories specified in the agreement. Ranbaxy does not have the right to manufacture BOW015.
	Ranbaxy made an upfront payment of $500 upon the execution of the agreement and is obligated to pay the Company up to $1,000 if certain development and regulatory approval milestones are achieved and up to $10,000 if certain sales milestones are achieved. Additionally, the Company is entitled to receive royalties in the mid-teens on net sales in the territories, which royalties are subject to reduction or renegotiation in certain limited circumstances. Under certain circumstances of uncured breach by the Company and termination of the License Agreement by Ranbaxy, monetary damages of $500, would be due to Ranbaxy.
	Unless terminated earlier in accordance with the terms of the agreement, the License Agreement with Ranbaxy expires 20 years following the first commercial sale in the territories.
	Under the License Agreement, Ranbaxy is responsible for all activities related to the commercialization of BOW015 in the territories. The Company is responsible for performing the development activities required for obtaining regulatory approval in India, joint steering committee participation and clinical and commercial supply of product. The Company also agreed to perform the development activities required to obtain regulatory approval in other parts of the territories. These activities and the related fees will be agreed upon by Ranbaxy and the Company in future written agreements.
	The Company has determined that the deliverables under the Ranbaxy agreement are the license, development activities related to regulatory approval in India, joint steering committee services and the obligation to supply clinical and commercial product. The Company's obligation to perform future development activities to obtain regulatory approval in other parts of the territories is not a deliverable at the inception of the agreement as the Company will be compensated separately for these activities, and it is uncertain at this time if the Company will ever be requested to perform these activities by Ranbaxy.
	The Company determined that the license and the other activities and services do not have standalone value apart from the requirement for the Company to deliver commercial material. Ranbaxy has not been granted a license to manufacture BOW015, which prevents them from using the license and related services for their intended purpose without the involvement of the Company. Therefore, the deliverables are not separable and represent one single unit of accounting. When multiple deliverables are accounted for as a single unit of accounting, the Company bases its revenue recognition pattern on the last to be provided deliverable. As a result, no revenue was recognized until delivery of the commercial supply began. All amounts received from Ranbaxy were recorded as deferred revenue prior to the delivery of the commercial supply began.
	The arrangement includes the delivery of commercial material and therefore does not qualify for the milestone method of revenue recognition as the agreement is not a research and development arrangement. As a result, upon achievement of a milestone, the amounts will be included in the total arrangement consideration. In January 2014, the Company invoiced Ranbaxy $125 related to the filing for approval in India. In March 2014, the Drug Controller General in India approved BOW015 for commercial sale to the Indian market, upon which a payment from Ranbaxy of $250 became due and payable and was invoiced in April 2014. In September 2014, the Company executed a supply agreement with Ranbaxy, upon which an additional milestone payment of $125 became due.
	On September 9, 2014, the Company entered into an amendment (the "Amendment") to the License Agreement. The Amendment amended the License Agreement to revise (i) the royalty tiers for net sales based on final product sale forecasts and supply costs in the territory, and (ii) Ranbaxy's obligations with respect to minimum annual sales targets in any given country such that the obligations are subject to a final grant of approval for BOW015 by the applicable regulatory authority for all indications as have been granted for the innovator product in such country. Other than as set forth in the Amendment, the License Agreement remains in full force and effect following the parties' execution of the Amendment.
	In September 2014, the Company and Ranbaxy entered into a supply agreement for BOW015 under which Epirus, through its third party manufacturing supplier, will provide Ranbaxy with finished products for clinical use, regulatory use and commercialization in accordance with the License Agreement. Under the terms of the supply agreement, the Company's designated manufacturer will receive consideration from Ranbaxy for commercial finished product. Unless terminated earlier in accordance with terms, the Company's supply agreement with Ranbaxy expires 10 years from the effective date, subject to five two-year automatic renewal periods.
	In November 2014, the Company launched Infimab (BOW015) and Ranbaxy completed the first commercial sale of Infimab in India, signifying commercial supply of product has commenced. Upon this event, an additional milestone of $250 became due and payable and the Company began to recognize revenue, over the remaining term of the License Agreement, associated with the upfront and milestone payments which were initially recorded as deferred revenue, excluding $500 which will remain deferred until the previously discussed breach and termination right lapses. As subsequent milestones are achieved, these payments will be recognized as revenue over the remaining term of the License Agreement, including the five two-year automatic renewal periods. Royalty revenues from sales of Infimab will be recognized one quarter in arrears in conjunction with the Company's accounting policy (Note 2).
	The Company has invoiced Ranbaxy for a total of $1,250, including the upfront payment, and received payments related to the agreement totaling $1,000 during the year ended December 31, 2014. The outstanding $250 due from Ranbaxy as of December 31, 2014 has been excluded from accounts receivable and deferred revenue.
	Orygen Biotechnology
	In September 2013, the Company entered into a binding Heads of Agreement ("Orygen Heads of Agreement") with Orygen Biotechnology ("Orygen"), a Brazilian corporation, for the negotiation of the terms of a definitive agreement under which Orygen would be granted exclusive rights to commercialize BOW015 in Brazil. As consideration for entry into the Orygen Heads of Agreement, and the rights to be granted under the definitive agreement, the Company received a non-creditable, non-refundable initial upfront cash payment of $250 from Orygen.
	The Orygen Heads of Agreement, as extended by the parties, was terminated on May 19, 2014. The Company recognized the $250 upfront cash payment as other income in the consolidated statement of operations and comprehensive loss in the year ended December 31, 2014.
	Livzon Mabpharm
	In September 2014, the Company entered into an Exclusive License and Collaboration Agreement (the "Agreement") with Livzon Mabpharm Inc. ("Livzon") for the global development and commercialization of certain antibodies or related biological compounds, including the Company's BOW015, a biosimilar version of infliximab.
	Under the Agreement, the Company and Livzon each agreed to grant the other party, in the other party's territory, exclusive, royalty-bearing licenses under certain patent rights and know-how to develop, manufacture and commercialize BOW015 and up to four additional compounds chosen by mutual agreement of the parties (collectively, the "Collaboration Compounds"). Livzon's territory consists of China, Hong Kong, Macau and Taiwan (the "Livzon Territory"), and the Company's territory consists of the rest of the world. The parties share pre-clinical development expenses for each Collaboration Compound based on certain factors specific to each compound. Each party bears the responsibility and expenses for clinical development and commercialization of each Collaboration Compound in its territory. Livzon will be the preferred supplier of each Collaboration Compound for pre-clinical, clinical, and commercialization purposes, subject to Livzon's satisfaction of certain performance criteria and subject to the negotiation of a separate supply agreement.
	As consideration for the license granted to Livzon to develop and commercialize BOW015, the Company is eligible to receive from Livzon a nonrefundable milestone payment of $2,500 upon the achievement of a specified regulatory milestone in the Livzon Territory. The Company is also eligible to receive from Livzon tiered royalties based on a percentage of net sales of BOW015 products in the Livzon Territory ranging from the low- to high-single digits. Any future Collaboration Compounds have cross-milestone and royalty obligations in amounts to be mutually agreed upon at a later date.
	If not terminated earlier or extended by mutual agreement of the parties, the Agreement expires in its entirety 20 years from the effective date.
	The Company determined that the substantive terms of the Agreement are those relating to the license granted to Livzon to develop and commercialize BOW015 and the related Technology Transfer, as defined in the Agreement, which is the know-how to develop and manufacture BOW015 as described above. Under the Agreement, Livzon is responsible for all activities related to the commercialization of BOW015 in the Livzon Territory. The Company is responsible for the Technology Transfer and a small amount of advisory services to Livzon.
	The Company has determined that the deliverables under the Agreement are the license, Technology Transfer and a small amount of advisory services. Additional obligations that may arise under the Agreement are not deliverables at the inception of the Agreement as the Company will be compensated separately for these activities, and it is uncertain at this time if the Company will ever be requested to perform these activities by Livzon.
	The Company determined that the license, Technology Transfer and advisory services do not have standalone value. The Technology Transfer is required to enable Livzon to manufacture BOW015. Without such capability, Livzon would not be able to use the license and services for their intended purpose without the involvement of the Company. Therefore, the deliverables are not separable and represent one single unit of accounting. When multiple deliverables are accounted for as a single unit of accounting, the Company bases its revenue recognition pattern on the last to be provided deliverable.
	The Company determined that the specified regulatory milestone is not substantive due to the lack of development activities required from the Company subsequent to the execution of the Agreement. As a result of the factors above, no revenue will be recognized until the milestone is achieved and the $2,500 will be recognized as revenue after the milestone is achieved, over the remaining period of the Technology Transfer. As of December 31, 2014, no amounts have been paid and no amounts have become due and payable under the Agreement.
	Moksha8 Pharmaceuticals
	In September 2014, the Company entered into an amendment (the "Amendment") to the Revenue and Negotiation Rights Agreement between the Company and Moksha8 Pharmaceuticals, Inc. ("Moksha8"), dated as of December 31, 2010 (the "Moksha8 Revenue Agreement"). Under the terms of the Moksha8 Revenue Agreement, the Company was required to pay to Moksha8 royalties based on nets sales of BOW015 by the Company or its affiliates at a percentage in the very low double digits, and a portion of all licensing revenue received by the Company from third parties to commercialize BOW015 at a percentage in the mid-teens, subject in each case to reduction in certain circumstances.
	The Amendment amends the Moksha8 Revenue Agreement to terminate the Company's royalty and revenue sharing payment obligations with respect to products that are biosimilars to infliximab, which includes the Company's BOW015 product, in exchange for the Company's payment of $1,500 in two installments.
	In October 2014, the Company entered into a second amendment (the "Second Amendment") to the Amendment between the Company and Moksha8. Under the terms of the Second Amendment, the $1,500 of payments described in the Amendment was reduced to $1,400. Pursuant to the Amendment and the Second Amendment, in October 2014 the Company made payments to Moksha8 totaling $1,400 and recorded an extinguishment of previously accrued royalty obligations of $150 and an intangible asset of $1,250 (Note 7).
	Moksha8 is owned in part by Montreux Equity Partners and TPG Capital, which are also shareholders of the Company. As of December 31, 2014, Montreux Equity Partners and TPG Capital each owned approximately 17% of the Company.

Merger

Merger	12 Months Ended
	Dec. 31, 2014
Merger
Merger	4. Merger
	As described in Note 1, "Organization," on July 15, 2014, the Company completed the Merger with Zalicus. Pursuant to the Merger Agreement, each share of capital stock of Private Epirus was exchanged for 0.13259 shares of Public Epirus Common Stock (the "Exchange Ratio"). All Private Epirus stock options granted under the Private Epirus stock option plans (whether or not then exercisable) that were outstanding prior to the effective time of the Merger, and all warrants to purchase Private Epirus capital stock that were outstanding prior to the effective time of the Merger were exchanged at the same ratio as described below. Upon the consummation of the Merger, equity holders of Private Epirus were issued an aggregate of 10,288,180 shares of Public Epirus Common Stock, plus 1,152,042 and 21,996 shares of Public Epirus Common Stock which could be issued in the future upon exercise of stock options and warrants, respectively.
	After the Effective Time, all outstanding and unexercised Private Epirus stock options assumed by Zalicus may be exercised solely for shares of Public Epirus Common Stock and all outstanding and unexercised warrants to purchase Private Epirus capital stock may be exercised solely for shares of Public Epirus Common Stock. The number of shares of Public Epirus Common Stock subject to each Private Epirus stock option or warrant assumed by Zalicus was determined by multiplying (a) the number of shares of Private Epirus common stock that were subject to such Private Epirus stock option or warrant, as in effect immediately prior to the Effective Time, by (b) the exchange ratio, as defined in the merger agreement, and rounding the resulting number down to the nearest whole number of shares of Public Epirus Common Stock. The per share exercise price for the Public Epirus Common Stock issuable upon exercise of each Private Epirus stock option or warrant assumed by Zalicus was determined by dividing (a) the per share exercise price of Private Epirus common stock subject to such Private Epirus stock option or warrant, as in effect immediately prior to the Effective Time, by (b) the Exchange Ratio and rounding the resulting exercise price up to the nearest whole cent.
	All Zalicus equity awards granted prior to the Merger remained legally outstanding.
	The Merger has been accounted for as a reverse acquisition under the acquisition method of accounting with Private Epirus treated as the accounting acquirer and Zalicus treated as the acquired company for financial reporting purposes. Private Epirus was determined to be the accounting acquirer based upon the terms of the Merger and other factors, such as relative voting rights and the composition of the combined company's board of directors and senior management. Accordingly, the Zalicus tangible and identifiable intangible assets acquired and liabilities assumed were recorded at fair value as of the date of acquisition, with the excess consideration transferred recorded as goodwill.
	See Note 13, "Stock-Based Compensation," for additional details regarding the accounting treatment for the equity awards of Private Epirus and Zalicus.
	The acquisition-date fair value of the consideration transferred is as follows:
	Number of shares of Public Epirus Common Stock owned by Zalicus stockholders(1)			2,635,871
	Multiplied by the price per share of Public Epirus Common Stock(2)		$	11.80
	Fair value of shares of Public Epirus Common Stock owned by Zalicus stockholders		$	31,104
	Acquisition-date fair value of assumed Zalicus equity awards attributable to precombination services(3)		$	220
	Total consideration transferred		$	31,324
	-1	The stock transferred in the table above is comprised of 2,610,871 common shares outstanding at the time of the Merger plus 25,000 restricted stock units (RSUs) that vested immediately upon the closing of the Merger. The fair value of shares of Public Epirus Common Stock owned by Zalicus shareholders of $31,104 includes approximately $1 related to fractional shares resulting from the Reverse Stock Split.
	-2	The shares outstanding are multiplied by the closing trading price of Public Epirus Common Stock as of the Merger date.
	-3	Consideration transferred includes approximately $220 of Zalicus equity awards assumed and deemed attributable to precombination services to Zalicus. This amount excludes approximately $355 of acquisition-date fair value attributable to postcombination service, which was recorded to reflect the acceleration of nonvested equity awards of Zalicus upon the termination of certain Zalicus employees after the Merger. The Company recognized the $355 as stock-based compensation expense in the postcombination period ended December 31, 2014 (Note 13). The fair value of the equity awards at July 15, 2014 was determined using a Black-Scholes option-pricing model with the following ranges of assumptions: exercise price of $14.70 per share to $591.00 per share; underlying stock value of $11.80 per share; expected volatility of 66.02%; expected term of 0.1 years to 6.0 years; and risk-free interest rate of 1.91%.
	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed at the date of acquisition:
			July 15, 2014
	Cash and cash equivalents		$	13,756
	In-process research and development			5,500
	Goodwill			14,864
	Restricted cash			1,850
	Other assets			253
	Total assets acquired			36,223
	Accounts payable			(1,584	)
	Accrued expenses			(381	)
	Other current liabilities			(376	)
	Other liabilities			(391	)
	Deferred tax liabilities			(2,166	)
	Total liabilities assumed			(4,899	)
	Total net assets acquired		$	31,324
	The purchase price allocation has been prepared on a preliminary basis and is subject to change as additional information becomes available concerning the tax basis of the assets acquired and the liabilities assumed. Any adjustments to the purchase price allocation as a result of a change in tax basis or rates will be made as soon as practicable but no later than one year from July 15, 2014, the acquisition date.
	For acquired working capital accounts such as accounts receivable, prepaid expenses and other current assets, accounts payable and certain accrued expenses, the Company determined that no fair value adjustments were required due to the short timeframe until settlement for these assets and liabilities.
	The fair value of the IPR&D was determined using the multi-period excess earnings method, a variation of the income approach, including a discount rate of 13.1% applied to the projected cash flows. The Company believes the assumptions used are consistent and representative of those a market participant would use in estimating the fair value of the IPR&D. The Company will not begin amortizing the IPR&D asset until the research and development is complete and the asset is reclassified to a definite-lived amortizing asset.
	Goodwill is calculated as the difference between the acquisition-date fair value of the consideration transferred and the fair values of the assets acquired and liabilities assumed. The goodwill is not expected to be deductible for income tax purposes. Goodwill is recorded as an indefinite-lived asset and is not amortized but tested for impairment on an annual basis or when indications of impairment exist.
	Other liabilities of $391 and $376 of other current liabilities relates to a sublease liability assumed for Zalicus' Cambridge, Massachusetts facility. The liability represents the fair value of the difference between the total sublease payments and the total payments for the facility per the lease agreement. The original lease and the sublease agreement terminate in January 2017.
	The deferred tax liability of $2,166 relates to the temporary difference associated with the $5,500 value of the IPR&D asset, which is not deductible for tax purposes. The deferred tax liability was recorded based on a 39.39% effective tax rate.
	The operating results of Zalicus for the period from July 16, 2014 to December 31, 2014, including an operating loss of $25, have been included in the Company's consolidated financial statements as of and for the year ended December 31, 2014.
	The Company incurred a total of $5,779 in transaction costs in connection with the Merger, excluding Zalicus transaction costs, which were included in general and administrative expense within the consolidated statements of income for the year ended December 31, 2014. The following supplemental unaudited pro forma information presents the Company's financial results as if the acquisition of Zalicus had occurred on January 1, 2013:
			Year Ended
			December 31,
			2014			2013
	Total revenues, net		$	2,739		$	14,731
	Net loss		$	(32,410	)	$	(69,630	)
	The above unaudited pro forma information was determined based on the historical GAAP results of the Company and Zalicus. The unaudited pro forma consolidated results are not necessarily indicative of what the Company's consolidated results of operations actually would have been if the acquisition was completed on January 1, 2013. The unaudited pro forma consolidated net loss includes pro forma adjustments primarily relating to the following non-recurring items directly attributable to the business combination:
	-1	Elimination of $8,673 of transaction costs for both the Company and Zalicus from the year ended December 31, 2014, and inclusion of these transaction costs in the year ended December 31, 2013;
	-2	Elimination of $355 of stock-based compensation expense related to the acceleration of vesting of previously unvested Zalicus awards in connection with the Merger from the year ended December 31, 2014, and inclusion of this charge in the year ended December 31, 2013;
	-3	Elimination of $1,980 of expense related to severance agreements from the year ended December 31, 2014, and inclusion of this charge in the year ended December 31, 2013; and
	-4	Elimination of $222 and $789 of other expense related to the change in the fair values of liability-classified warrants from the years ended December 31, 2014 and 2013, respectively, as the Company's outstanding warrants were reclassified to equity in connection with their exchange in the Merger.

Prepaid_Expenses_and_Other_Cur

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2014
Prepaid Expenses and Other Current Assets.
Prepaid Expenses and Other Current Assets	5. Prepaid Expenses and Other Current Assets
	Prepaid expenses and other current assets consisted of the following:
		As of
		December 31,
		2014		2013
	Prepaid clinical expenses	$	5	$	599
	Prepaid manufacturing expenses		457		194
	Prepaid other expenses		633		85
	Other current assets		461		10
	Total prepaid and other current assets	$	1,556	$	888

Property_and_Equipment_Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2014
Property and Equipment, Net.
Property and Equipment	6. Property and Equipment, Net
	Property and equipment consisted of the following:
		As of
		December 31,
		2014			2013
	Computer equipment	$	173		$	70
	Furniture and fixtures		116			49
	Leasehold improvements		504			10
	Total property and equipment		793			129
	Less: accumulated deprecation		(89	)		(39	)
	Property and equipment, net	$	704		$	90
	Depreciation expense related to property and equipment amounted to $83 and $31 for the years ended December 31, 2014 and 2013, respectively.

Goodwill_IPRD_and_Intangible_A

Goodwill, IPR&D and Intangible Assets, Net	12 Months Ended
	Dec. 31, 2014
Goodwill, IPR&D and Intangible Assets, Net
Goodwill, IPR&D and Intangible Assets, Net	7. Goodwill, IPR&D and Intangible Assets, Net
	Goodwill
	The following table represents changes in goodwill for the fiscal year ended December 31, 2014:
	Balance at December 31, 2013	$	1,499
	Goodwill related to Merger		14,864
	Balance at December 31, 2014	$	16,363
	As of December 31, 2014, there were no accumulated impairment losses. Goodwill has been assigned to the Company's single reporting unit, which is the single operating segment by which the chief operating decision maker manages the Company (Note 2).
	IPR&D
	The Company's IPR&D asset relates to the development and commercialization of product candidates acquired by the Company. During the years ended December 31, 2014 and 2013, the Company's IPR&D related to product candidates Z944 and BOW015, respectively..
	In connection with the Merger in 2014, the Company recognized IPR&D related to product candidate Z944. The carrying value of the IPR&D related to Z944 as of December 31, 2014 was $5,500. See Note 4 "Merger" for additional details. During the first quarter of 2015, the Company began pursuing a sale of this asset and believes that such a sale will take place in the next 12 months
	The IPR&D asset as of December 31, 2013 relates to the development and commercialization of the Company's lead product candidate, BOW015. In July 2014, the Company received the necessary approvals to manufacture and market BOW015 in India. Upon such approval for commercialization in India, the $2,437 of IPR&D associated with BOW015 was reclassified from an indefinite-lived asset to a finite lived asset. The carrying value of the IPR&D related to BOW015 was $0 and $2,374 as of December 31, 2014 and 2013, respectively.
	Intangibles
	As described above, in July 2014, the Company reclassified the $2,437 of IPR&D associated with BOW015 from an indefinite-lived asset to a finite-lived asset. During the year ended December 31, 2014, the Company began amortizing the intangible asset over its expected useful life of approximately 16.5 years. The Company determined the useful life of the asset based upon the period over which the Company expects to earn future economic benefit for BOW015. The Company recognizes amortization expense utilizing the straight-line method.
	As described in Note 3, "Business Agreements," in September 2014 and October 2014, the Company entered into the Amendment and Second Amendment, respectively, which amended the Moksha8 Revenue Agreement to terminate the Company's revenue sharing payment obligations with respect to products that are biosimilars to infliximab, in exchange for payments of $1,400. In connection with the payments under the Amendment and Second Amendment, in September 2014, the Company recorded an intangible asset of $1,250, which will be amortized over the expected useful life of the intangible asset associated with BOW015, described above.
	Intangible assets, net of accumulated amortization is as follows:
		December 31, 2014			December 31, 2013
	Intangible assets	$	3,687		$	—
			3,687			—
	Less: accumulated amortization—intangible assets		(82	)		—
	Intangible assets, net	$	3,605		$	—
	Amortization expense, which is included within research and development expense in the consolidated statements of operations and comprehensive loss, was $82 and $0 for the year ended December 31, 2014 and 2013, respectively.
	The estimated aggregate amortization of intangible assets as of December 31, 2014, for each of the five succeeding years and thereafter is as follows:
		December 31, 2014
	2015	$	225
	2016		225
	2017		225
	2018		225
	2019		225
	2020 and thereafter		2,480
	Total	$	3,605

Accrued_Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Accrued Expenses
Accrued Expenses	8. Accrued Expenses
	Accrued expenses consisted of the following:
		December 31, 2014		December 31, 2013
	Accrued professional fees	$	1,822	$	544
	Accrued compensation		1,244		725
	Accrued manufacturing expense		813		380
	Accrued clinical expense		63		286
	Accrued interest expense		71		502
	Other		88		55
	Total accrued expenses	$	4,101	$	2,492

Debt

Debt	12 Months Ended
	Dec. 31, 2014
Debt
Debt	9. Debt
	2013 Notes
	On March 13, 2013, the board of directors approved the issuance of $7,500 of convertible notes. The notes bore interest at a rate of 8% per annum and provide the holders of the notes with 20% warrant coverage. The Company received proceeds of $5,000 on March 13, 2013, and $2,500 on July 8, 2013. On October 1, 2013, the board of directors approved the issuance of an additional $5,000 of convertible notes. The notes bear interest at a rate of 8% per annum and provide the investors of the notes with 20% warrant coverage. The Company received proceeds of $1,667 on October 1, 2013, and the remaining $3,333 on October 31, 2013. All of the notes had a maturity date of December 31, 2013.
	The 2013 convertible notes were: (1) automatically convertible upon the consummation of a qualifying equity fundraising of gross proceeds of at least $20,000, excluding proceeds from the convertible note issuances, into the class of shares to be issued to investors participating in the fundraising at a conversion price per share equal to 80% of the price per share paid by other investors; (2) convertible at the election of holders of at least 60% of the aggregate outstanding principal amount of the notes, upon the consummation of a non-qualifying equity fundraising, defined as the issuance of convertible preferred stock that does not constitute a qualified financing, into either the class of shares to be issued to investors participating in the fundraising at a conversion price per share equal to 80% of the price per share paid by other investors or Series A convertible preferred stock ("Series A Preferred") at a price of $1.00 per share; (3) automatically puttable upon the consummation of a change of control through an acquisition or asset transfer into cash equal to three times the outstanding principal, plus accrued but unpaid interest through the date of payment; and (4) convertible into Series A Preferred at a price of $1.00 per share, at the option of the holders of at least 60% of the nominal amount of the aggregate outstanding principal amount of the notes upon the notes not being converted under another method as of the maturity date.
	In connection with the 2013 convertible notes issuances, the Company issued to the note purchasers warrants to purchase an aggregate of 2,499,996 shares of Series A Preferred with an exercise price of $0.01 per share, subject to certain limitations and adjustments. The aggregate fair values of the warrants at their issuance dates of $2,472 (Note 10) were recorded as a discount to the respective convertible notes.
	The Company determined the convertible notes issued during 2013 contain a BCF aggregating $2,440, which was recorded as a debt discount. The debt discounts were amortized to interest expense using the effective interest method over the period between the issuance dates and the maturity date. The debt discounts on the notes issued in 2013 were fully amortized as of December 31, 2013, and the carrying value of the convertible notes was $12,500.
	As of December 31, 2013, the convertible notes principal outstanding and all accrued but unpaid interest was due and payable. On March 10, 2014, the $12,500 principal amount of convertible notes outstanding at December 31, 2013, plus accrued but unpaid interest of $684, were converted into 13,184,383 shares of Series A convertible preferred stock.
	March 2014 Notes
	On March 10, 2014, the Company issued and sold $5,000 of convertible notes to finance the operations of the Company. The notes bore interest at a rate of 8% per annum, had a maturity date of April 30, 2014 and provided the holders of the notes with 20% warrant coverage.
	The 2014 note agreements contained the following settlement provisions: (1) in the event of a qualified financing in which the Company issues and sells shares of preferred stock for gross proceeds of at least $20,000 from one or more persons that are not current holders of capital stock, prior to the maturity date of the note, all outstanding principal and accrued interest automatically converts into the same class and series of capital stock at the price paid per share by the other purchasers in the qualified financing event; (2) in the event of a corporate merger, all outstanding principal and accrued interest automatically converts into the Company's Series A Preferred at a conversion price equal to $1.00 per share; (3) in the event of an acquisition or asset transfer, the Company shall pay the outstanding note holders an amount in cash accrued and unpaid interest through the date of the payment and three times the outstanding principal balance; (4) in the event of a non-qualified financing, holders of the notes shall have the option to either convert all outstanding principal and any accrued but unpaid interest into shares of the same class and series of capital stock at the conversion price equal to the price per share of the non-qualified financing securities, or into shares of Series A Preferred, at a conversion price equal to $1.00 per share; (5) following the maturity date of the note, upon a written election by a majority of note holders, all outstanding principal and accrued interest converts into Series A Preferred; and (6) in the event of a default, all outstanding principal and accrued interest becomes immediately due and payable without notice or demand. The warrants were immediately exercisable into 1,000,000 shares of Series A Preferred at an exercise price of $0.01 per share. In the event of a qualified financing, the warrants become exercisable into a number of shares of the preferred stock issued in the qualified financing that represents $1,000 divided by the price per share of the preferred stock.
	The provisions requiring conversion or prepayments of the 2014 notes upon a qualified financing, a corporate merger, an acquisition or asset transfer, or an event of default constituted an embedded compound derivative that is being accounted for separately. The Company determined that the fair value of this embedded compound derivative upon the issuance of the 2014 notes was $23, which was subtracted from the original carrying amount of the 2014 notes and reflected as a debt discount, and also increased liabilities by $23.
	The Company determined the 2014 notes contained a beneficial conversion feature ("BCF") measured at $2,071, which was recorded as a discount to the convertible notes.
	The aggregate fair value of the warrants at their issuance date was $1,171, which was also recorded as a discount to the convertible notes.
	The total debt discount resulting from the embedded compound derivative, BCF, warrants and lender fees is being amortized as interest expense using the effective interest method over the period between the convertible notes' issuance and maturity date.
	On April 15, 2014, upon the closing of a qualified financing, the issuance of Series B convertible preferred stock ("Series B Preferred") (Note 12), the $5,000 principal amount of convertible notes issued in March 2014, plus accrued and unpaid interest of $13, were converted into 3,947,363 shares of Series B Preferred and the warrants became exercisable into 787,402 shares of Series B Preferred at an exercise price per share of $0.01.
	The conversion of the notes into Series B Preferred was accounted for as an extinguishment of the notes and a repurchase of the BCF. In accordance with the accounting guidance for extinguishments of convertible debt with embedded BCFs, the Company recorded a reduction of additional paid-in capital of $1,150, which represents the intrinsic value of the BCF at the time of extinguishment, and a gain on the extinguishment of the notes of $22 during the year ended December 31, 2014, which represents the difference between the net carrying value of the notes at the time of extinguishment in excess of the remainder of the consideration transferred after the $1,150 allocated to the repurchase of the BCF, plus the derecognition of the $23 derivative liability. Consideration transferred was $5,013, which is the fair value of the shares of Series B Preferred into which the notes converted. The gain was recorded to other income (expense) within the consolidated statement of operations and comprehensive loss.
	Hercules Notes
	On September 30, 2014, the Company entered into a Loan and Security Agreement (the "Loan Agreement") with Hercules Technology Growth Capital, Inc. ("Hercules"). Under the Loan Agreement, Hercules will provide the Company with access to two term loans with an aggregate principal amount of up to $15,000 (collectively, the "Loan"). The first term loan ("Tranche 1"), with a principal amount of $7,500, was funded on October 1, 2014. The second term loan ("Tranche 2"), with a principal amount of up to $7,500, may be drawn down at the Company's option at any time between September 30, 2014 and the earlier of (i) May 30, 2015 or (ii) an Event of Default (the "Draw Period"). The Loan is repayable in monthly installments until April 1, 2018, including an initial interest-only period of 18 months after funding of Tranche 1. Any amounts remaining outstanding at April 1, 2018 will become due immediately. Under the current repayment schedule, this amount is expected to be $1,897. The interest-only period may be extended at the Company's request to November 1, 2016, contingent upon the Company's first patient being dosed in a pivotal clinical study of BOW015 (infliximab) for approval in the European Union prior to May 1, 2016. Upon the Company's request to extend the interest free period, the maturity date of the Loan is also extended to October 1, 2018, at which time any amounts remaining outstanding will become due immediately. The interest rate is a floating interest rate equal to the greater of (i) 7.95%, or (ii) the sum of (A) 7.95%, plus (B) the Prime Rate minus 3.25% per annum. An end of term charge equal to 3.00% of the aggregate original principal balance of the Loan is payable at maturity, including in the event of any prepayment, and is being accrued as interest expense over the term of the loan using the effective interest method. Borrowings under the 2014 Loan Agreement are collateralized by substantially all assets of the Company.
	If the Company repays all or a portion of the term loans prior to maturity, it will pay Hercules a prepayment fee as follows: (i) 2.00% if the prepayment occurs in the first 18 months following the funding date and (ii) no fee if the prepayment occurs after the first 18 months following the funding date.
	The Company may elect to pay, in whole or in part, any regularly scheduled installment of principal up to an aggregate maximum amount of $2,000 by converting a portion of the principal into shares of the Company's common stock at a rate of $8.06 per share, subject to certain conditions including the Company's stock trading at a level greater than the this rate for seven consecutive trading days and the shares to be issued not exceeding 15% of the Company's total trading volume for the previous 22 consecutive trading days.
	An Event of Default is defined in the Loan Agreement as (i) failure to make required payments; (ii) failure to adhere to Term Loan Advance covenants; (iii) an event or development occurs that has a material adverse effect (a material adverse effect upon: a) the business, operations, properties assets, prospects or condition (financial or otherwise) of the Company, b) the ability of the Company to perform its obligations under the agreement, or c) the collateral or agent's liens on the collateral or the priority of such liens); (iv) false representations in the Loan Agreement; (v) insolvency, as described in the Loan Agreement; (vi) levy or attachments on any of the Company's assets; (vii) default of any other agreement or subordinated debt greater than $250; and (viii) a U.S. Securities and Exchange Commission ("SEC") stop trade order or NASDAQ market trading suspension. Upon an Event of Default, an additional 4% interest will be applied and Hercules may, at its option, accelerate and demand payment of all of any part of the loan together with the prepayment charge. In the event of insolvency, this acceleration and declaration would be automatic. In addition, in connection with the Loan Agreement, the Company agreed to provide Hercules with a contingent security interest in the Company's bank accounts. The Company's control of its bank accounts are not adversely affected unless Hercules elects to obtain unilateral control of the Company's bank accounts by declaring that an Event of Default has occurred. The principle of Tranche 1, which is not due within 12 months of December 31, 2014 has been classified as long-term as the Company determined a material adverse effect, and therefore Hercules exercising its rights under the subjective acceleration clause, is remote.
	Pursuant to the Loan Agreement, subject to certain terms, Hercules was granted the right to participate, in an amount of up to $1,000, in subsequent sales and issuances of the Company's equity securities to one or more investors for cash for financing purposes in an offering that is broadly marketed to multiple investors and at the same terms as the other investors.
	Debt issuance costs of approximately $49 have been ratably allocated to each of the two tranches based upon the total principal amount available to the Company under each tranche. Debt issuance costs related to Tranche 1 are being amortized over the term of the loan using the effective interest method. Issuance costs related to Tranche 2 are being amortized ratably over the Draw Period. Upon a draw down under Tranche 2, the remaining unamortized debt issuance costs will be amortized over the remaining life of the Tranche 2 term loan using the effective interest method.
	In connection with the Loan Agreement, on September 30, 2014, the Company issued to Hercules a warrant to purchase 64,194 shares of Public Epirus Common Stock at an exercise price of $7.01 per share. The Warrant's fair value of $248 at September 30, 2014 was determined using a Black-Scholes option-pricing model. See Note 10, "Warrants," for further description of the warrant.
	In addition to the warrants, the Company paid a facility fee and legal costs on behalf of Hercules in conjunction with obtaining the Loan. The warrant fair value, the Hercules legal costs, and the facility fee, an aggregate of $463, were ratably allocated to each of the two tranches based upon the total principal amount available to the Company under each tranche. The costs of approximately $231 allocated to Tranche 1 were recorded as a debt discount and are being amortized as additional interest expense over the term of the loan using the effective interest method. The costs allocated to Tranche 2 were recorded as prepaid expenses and other current assets and are being amortized ratably over the Draw Period. Upon a draw down under Tranche 2, the remaining unamortized costs will be reclassified to debt discount and will be amortized over the remaining life of the Tranche 2 term loan using the effective interest method.
	As of December 31, 2014, the Company had outstanding borrowings under the 2014 Loan Agreement of $7,500. As of December 31, 2014, on the Company's balance sheet, the Company has recorded a long-term debt obligation of $7,282, net of debt discount of $218. Amortization of the debt discount, which was recorded as interest expense in the statement of operations, was approximately $14 for the period ended December 31, 2014.
	Future principal payments, which exclude the 3% end of term charge, in connection with the 2014 Loan Agreement, as of December 31, 2014 are as follows:
		Principal
		Payments
	2015	$	—
	2016		1,851
	2017		2,971
	2018		2,678
	Total	$	7,500

Warrants

Warrants	12 Months Ended
	Dec. 31, 2014
Warrants
Warrants	10. Warrants
	Prior to the Merger, Zalicus issued warrants to purchase common stock to certain third parties. Zalicus issued warrants to purchase 148 shares of common stock to General Electric Capital Corporation with an exercise price of $405.00 per share that expire on June 28, 2015 and warrants to purchase 1,079, 1,887 and 3,737 shares of common stock to Oxford at exercise prices of $83.40, $135.00 and $68.40 per share, respectively. The Oxford warrants expire on December 22, 2017.
	The Company issued warrants to purchase shares of the Company's Series A Preferred at various dates during and between the years ended December 31, 2011 and 2013, in connection with various financing arrangements, including the issuance of convertible notes and the issuance of Series A Preferred, and to one of the Company's Series A Preferred investors for services provided. All of the warrants to purchase Series A Preferred were initially recorded as liabilities that must be remeasured at each reporting period (see Note 11 for additional information regarding the measurement of fair value of the warrant liabilities).
	During the year ended December 31, 2013, the Company issued warrants to purchase 2,499,996 shares of Series A Preferred as follows:
	-1	999,999 warrants with a fair value of $826 issued in connection with the issuance of convertible notes on March 13, 2013;
	-2	499,998 warrants with a fair value of $494 issued in connection with the issuance of convertible notes on July 8, 2013;
	-3	333,333 warrants with a fair value of $384 issued in connection with the issuance of convertible notes on October 1, 2013; and
	-4	666,666 warrants with a fair value of $768 issued in connection with the issuance of convertible notes on October 31, 2013.
	Each warrant issued during 2013 was immediately exercisable, generally expires approximately seven years from the original date of issuance and had an exercise price of $0.01. Each warrant is exercisable on either a physical settlement or net share settlement basis.
	Warrants to purchase 498,306 shares of Series A Preferred were exercised at a price of $0.01 per share in the year ended December 31, 2013.
	In March 2014, the Company issued warrants, in connection with a convertible notes issuance, to purchase 1,000,000 shares of Series A Preferred with an exercise price of $0.01 per share (Note 9). Upon the Series B Preferred financing described in Notes 9 and 12, these warrants became exercisable into 787,402 shares of Series B Preferred at an exercise price of $0.01 per share. The aggregate fair value of such warrants at their issuance date was $1,171. Each warrant was immediately exercisable and expires approximately seven years from the original date of issuance. Each warrant was exercisable on either a physical settlement or net share settlement basis.
	In April 2014, warrants to purchase 5,101,816 shares Series A Preferred were exercised into 5,101,816 shares of Series A Preferred. In April 2014, the warrants to purchase Series B Preferred were exercised into 787,402 shares of Series B Preferred.
	In connection with the Merger on July 15, 2014, all of the Company's outstanding warrants exercisable for shares of preferred stock were exchanged for warrants exercisable for shares of Public Epirus Common Stock, which resulted in the reclassification of the liability-classified warrants to additional paid-in capital.
	See Note 11, "Fair Value Measurements," for additional details.
	As described in Note 9, the Company entered into a Loan Agreement with Hercules under which the Company was given access to up to $15,000 of term loans. As consideration for the Loan Agreement, on September 30, 2014, the Company issued Hercules warrant to purchase 64,194 shares of its common stock at an exercise price of $7.01 per share (the "Warrant"), which expires five years from issuance. The Warrant's fair value of $248 at September 30, 2014 was determined using a Black-Scholes option-pricing model with the following assumptions: expected volatility of 61.68%; contractual term of five years; and risk-free interest rate of 1.78%. The fair value of the warrant was recorded ratably to debt discount and prepaid expenses and other current assets, as described in Note 9, and credited to additional paid-in capital.
	As of December 31, 2014, all of the Company's outstanding warrants were classified in equity. As of December 31, 2014, the following warrants to purchase common stock were outstanding:
			As of December 31, 2014
			Number of		Exercise
			Shares		Price Per
			Underlying		Share
			Warrants
	Common Stock			1,379	$	0.08
	Common Stock			64,194	$	7.01
	Common Stock			20,616	$	7.55
	Common Stock			3,737	$	68.40
	Common Stock			1,079	$	83.40
	Common Stock			1,887	$	135.00
	Common Stock			148	$	405.00
	As of December 31, 2013, the following liability-classified warrants to purchase preferred stock were outstanding:
			As of December 31, 2013
			Number of		Exercise		Fair Value at
			Shares		Price Per		December 31,
			Underlying		Share		2013
			Warrant
	Series A Preferred			462,399	$	1.00	$	311
	Series A Preferred			4,805,327	$	0.01	$	5,532
	As of December 31, 2014, the Company did not have any liability-classified warrants.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Measurements
Fair Value Measurements	11. Fair Value Measurements
	The following table summarizes the financial assets and liabilities measured at fair value on a recurring basis in the accompanying balance sheets as of December 31, 2014 and 2013:
			As of December 31, 2014
			Level 1			Level 2		Level 3		Total
	Assets
	Cash and cash equivalents		$	21,462		$	—	$	—	$	21,462
			$	21,462		$	—	$	—	$	21,462
			As of December 31, 2013
			Level 1			Level 2		Level 3		Total
	Assets
	Cash and cash equivalents		$	1,798		$	—			$	1,798
			$	1,798		$	—	$	—	$	1,798
	Liabilities
	Warrant liability		$	—		$	—	$	5,843	$	5,843
			$	—		$	—	$	5,843	$	5,843
	As of December 31, 2014, the Company did not have any liabilities measured at fair value on a recurring basis.
	Warrant Liability
	The warrant liability represented the liability for warrants to purchase shares of Series A Preferred issued to investors in connection with the Company's Series A Preferred financings and issued to holders of the Company's convertible notes. The warrant liability was calculated using the Black-Scholes option-pricing model. This valuation method used inputs such as fair value of the Company's Series A Preferred and Series B Preferred shares, historical volatility, the term of the warrant and risk-free interest rates. At June 30, 2014, April 15, 2014, March 31, 2014 and December 31, 2013, the fair value of the Series A Preferred and Series B Preferred were determined using a hybrid of the probability-weighted expected return method ("PWERM") and the option-pricing method ("OPM") ("Hybrid Method"). At December 31, 2014, the Company did not have any warrants classified as liabilities.
	The PWERM is a scenario-based analysis that estimates the value per share based on the probability-weighted present value of expected future investment returns, considering each of the possible outcomes available to us, as well as the economic and control rights of each share class. Under the OPM, shares are valued by creating a series of call options with exercise prices based on the liquidation preferences and conversion terms of each equity class. The values of the preferred and common stock are inferred by analyzing these options.
	The hybrid method is a hybrid between the PWERM and the OPM, estimating the probability-weighted value across multiple scenarios but using the OPM to estimate the allocation of value within one of or more of those scenarios. In this valuation the hybrid model considers two possible outcomes: (1) an initial public offering ("IPO") or a reverse merger scenario and (2) continued operations as a private company scenario, which is modelled using the OPM.
	For the IPO or reverse merger scenario, equity value was estimated using the guideline public company ("GPC") method under the market approach and the discounted cash flow ("DCF") method under the income approach. Under the GPC method, equity value was estimated as a multiple of paid-in capital, using the median multiple indicated by selected initial public offerings by biotechnology companies. For the DCF method used in the April 15, 2014, March 31, 2014 and December 31, 2013 valuation, a discount rate of 22%, 30% and 35%, respectively, was assumed.
	In the OPM, equity value was estimated by back-solving the overall hybrid value such that the result is equal to the anticipated price of a future preferred stock series. The OPM used in the March 31, 2014 and December 31, 2013 valuation assumed 2.53 and 2.75 years to liquidity, respectively, and annual volatility of 58% and 53%, respectively.
	In the OPM analysis as of April 15, 2014, equity value was estimated by back-solving the overall hybrid value to the actual price per share of Series B Preferred paid in the issuance on April 15, 2014. The OPM used in the April 15, 2014 valuation assumed 2.46 years to liquidity and annual volatility of 59%.
	For the valuation analysis as of June 30, 2014, equity value under the IPO scenario was calculated based on the actual terms of the Merger, as described in Note 1, "Organization," and Note 4, "Merger," and the closing trading price per share of Zalicus common stock as of June 30, 2014. In the OPM analysis as of June 30, 2014, equity value was estimated using by back-solving the overall equity value to the actual price per share of Series B Preferred paid in the issuance on April 15, 2014. The OPM used in the June 30, 2014 valuation assumed 2.25 years to liquidity and annual volatility of 59%.
	In connection with the Merger on July 15, 2014, all of the Company's outstanding warrants exercisable for shares of preferred stock were exchanged for warrants exercisable for shares of Public Epirus Common Stock, which resulted in the reclassification of the liability-classified warrants to additional paid-in-capital. As of July 15, 2014, immediately prior to their exchange and reclassification, all of the Company's outstanding warrants were remeasured at fair value with the increase in the fair value recorded to other expense in the consolidated statement of operations and comprehensive loss. The fair value of such warrants of $167 at July 15, 2014 was determined using a Black-Scholes option-pricing model with the following ranges of assumptions: exercise price of $0.08 per share to $7.55 per share; underlying stock value of $11.80 per share; expected volatility of 61.58% to 64.96%; contractual term of 3.53 years to 5.10 years; and risk-free interest rate of 1.34% to 1.70%. As of December 31, 2014, the Company does not have any warrants measured using Level 3 inputs.
	Changes in the fair value of the warrant liability where fair value is determined using Level 3 inputs, were as follows:
			December 31,
			2014
	Balance at December 31, 2013		$	5,843
	Warrant issuance			1,171
	Change in fair value			222
	Warrant exercises			(7,069	)
	Reclassification to equity			(167	)
	Balance at December 31, 2014		$	—
	Embedded Derivative
	On March 10, 2014, the Company issued $5,000 of convertible notes that contained an embedded compound derivative as described in Note 9. The fair value of the embedded compound derivative was calculated using the "with and without" method. This valuation method first values the notes with the embedded compound derivative ("with" scenario) and subsequently values the notes without the embedded compound derivative ("without" scenario). The difference between the fair value of the notes in the "with and without" scenarios is determined to be the fair value of the embedded compound derivative as of the valuation date.
	Accordingly, the valuation of the embedded compound derivative was determined using Level 3 inputs.
	Changes in the fair value of the embedded compound derivative where fair value is determined using Level 3 inputs, were as follows:
			December 31,
			2014
	Balance at December 31, 2013		$	—
	Embedded compound derivative			23
	Change in fair value			—
	Derecognition of embedded compound derivative			(23	)
	Balance at December 31, 2014		$	—
	The following table provides quantitative information about the fair value measurements, including the range of assumptions for the significant unobservable inputs used in the hybrid method valuations of the warrant liability and "with and without" method used for the embedded compound derivative:
			Valuation Assumptions as of
			June 30, 2014		April 15, 2014		March 31, 2014	March 10, 2014
	Hybrid approach
	Discount rate		*		21% to 30%		25% to 30%	25% to 30%
	Probability weighted value for common stock		20% to 80%		30% to 70%		45% to 55%	45% to 55%
	Discount for lack of marketability		5% to 30%		11% to 34%		10% to 28%	10% to 28%
	With and Without approach
	Probability of occurrence of certain events		**		0% to 100%		5% to 50%	5% to 50%
	Market yield		**		25%		25%	25%
	Recovery rate		**		31% to 47%		31% to 47%	31% to 47%
	*	Discount rate not used as DCF was not calculated.
	**	No compound derivative to fair value at June 30, 2014.
	Significant increases (decreases) in the significant unobservable inputs used in the fair value measurement of the warrant liability and the embedded compound derivative in isolation would result in significantly higher (lower) fair value measurements.

Capital_Stock

Capital Stock	12 Months Ended
	Dec. 31, 2014
Capital Stock
Capital Stock	12. Capital Stock
	As of December 31, 2014, the Company had authorized 300,000,000 shares of common stock, $0.001 par value per share, of which 12,934,102 shares were issued and 12,920,843 shares were outstanding. Additionally, as of December 31, 2014, the Company had authorized 5,000,000 shares of preferred stock, $0.001 par value per share, of which zero were issued and outstanding.
	As of July 15, 2014, the Company amended its certificate of incorporation to increase the authorized capital stock of the Company to 305,000,000 shares, which included 300,000,000 shares of common stock, $0.001 par value per share.
	Reserved for Future Issuance
	The Company has reserved for future issuances the following number of shares of common stock:
		As of December 31,
		2014		2013
	Conversion of Preferred Stock		—		27,248,746
	Stock-based compensation awards		4,403,266		740,470
	Warrants to purchase preferred stock		—		5,267,726
	Warrants to purchase common stock		93,040		—
	Settlement of long-term debt		248,093		—
	Total		4,744,400		33,256,942
	Convertible Preferred Stock
	In April 2014, Epirus closed an initial Series B Preferred financing with an issuance of 24,409,444 shares for aggregate proceeds of approximately $31,000. Upon the closing of such financing, the $5,000 principal amount of convertible notes issued in March 2014, plus accrued and unpaid interest of $13, were converted into 3,947,363 shares of Series B Preferred (Note 9).
	Upon the closing of the Merger, all outstanding shares of preferred stock were exchanged for shares of Public Epirus Common Stock as part of the Merger at the Exchange Ratio. See Note 4, "Merger," for additional details. As of December 31, 2014, the Company did not have any convertible preferred stock issued or outstanding.
	Prior to the exchange of preferred stock for Public Epirus Common Stock, the Series A Preferred and Series B Preferred had the following terms:
	Series A Preferred
	Conversion
	Each share of Series A Preferred was convertible at the option of the holder, at any time and from time to time, into fully paid and non-assessable shares of common stock as was determined by dividing the original issuance price by the then applicable conversion price (equal to the original issuance price at all dates Series A Preferred was outstanding).
	Voting Rights
	The holders of Series A Preferred and Series B Preferred were entitled to vote as one class, with common stockholders, based on the number of shares of common stock each holder would receive upon conversion of their Series A Preferred or Series B Preferred into shares of common stock, for all matters except for the approval of certain major actions by the Company and the election of directors. Subject to certain ownership thresholds and approval rights set forth in the Company's amended and restated certificate of incorporation and an amended and restated voting agreement by and among certain stockholders of the Company, directors were elected as follows: the holders of Series B Preferred voted as a separate class for the election of one director; the holders of Series A Preferred voted as a separate class for the election of three directors; the holders of common stock voted as a separate class for the election of one director, which shall have been the currently serving chief executive officer; and the holders of common stock, and Series A Preferred and Series B Preferred, on an as-converted basis, voted together as a single class for the election of any remaining directors. If the common stock of the Company or any affiliate of the Company was not listed on a national securities exchange or other public trading platform on or prior to October 15, 2014, then the Series B Preferred stockholders would thereafter have been entitled to elect two members of the board of directors.
	Dividends
	Holders of Series A Preferred were entitled to receive, when and if declared by the board of directors, dividends at the rate of 8% of the original issuance price. Series A Preferred dividends were non-cumulative. In addition to the non-cumulative 8% dividend, the Series A Preferred shares would have also received (on an "as-converted" basis) the same dividend as that declared on common stock shares. The order of preference in the event of a dividend distribution, when and if declared by the board of directors, would have been first made to holders of Series B Preferred, then to holders of Series A Preferred and lastly to holders of common stock. No dividends were ever declared or paid.
	Liquidation Rights
	In the event of a voluntary or involuntary liquidation, dissolution, change in control or winding up of the Company, holders of Series A Preferred were entitled to be paid out second, following holders of Series B Preferred, of the assets available at a rate of the original issue price, plus any accrued but unpaid dividends, prior to any payment being made to holders of common stock.
	If the assets of the Company available for distribution to stockholders were insufficient to permit payment of the full amount to which each stockholder is entitled, holders of shares of the Series A Preferred would have shared ratably in any distribution of the remaining assets of the Company in proportion to the respective amounts which would otherwise have been payable under the circumstances in the order of liquidation preference.
	After the payment of the full liquidation preference of the preferred stock, the remaining assets, if any, would have been distributed ratably to the holders of preferred stock and common stock on an as-if-converted to common stock basis provided that if the aggregate amount the holders of the Series A Preferred were entitled to receive exceeded three times the original issue price plus all declared and unpaid dividends thereon (the "Maximum Participation Amount"), such holders would have been entitled to receive the greater of the Maximum Participation Amount or the amount they would have received if all shares of preferred stock had been converted into common stock immediately prior to the liquidation event.
	Because liquidation rights included a change in control, the Series A Preferred was classified within temporary equity. However, since a change in control was not considered probable, no adjustment to the carrying amount was required at any date the Series A Preferred was outstanding.
	Series B Preferred
	Conversion
	Each share of Series B Preferred was convertible at the option of the holder, at any time and from time to time, into fully paid and non-assessable shares of common stock as was determined by dividing the original issuance price by the then applicable conversion price (equal to the original issuance price at all dates Series A Preferred was outstanding).
	Voting Rights
	Holders of Series B Preferred and Series A Preferred were entitled to vote as one class, with common stockholders, based on the number of common stock each holder would receive upon conversion of their Series A or Series B Preferred into shares of common stock, for all matters except for the approval of certain major actions by the Company and the election of directors. Subject to certain ownership thresholds and approval rights set forth in the Company's amended and restated certificate of incorporation and an amended and restated voting agreement by and among certain stockholders of the Company, directors were elected as follows: the holders of Series B Preferred voted as a separate class for the election of one director; the holders of Series A Preferred voted as a separate class for the election of three directors; the holders of common stock voted as a separate class for the election of one director, which would have been the currently serving chief executive officer; and the holders of common stock, and Series A Preferred and Series B Preferred, on an as-converted basis, voted together as a single class for the election of any remaining directors. If the common stock of the Company or any affiliate of the Company was not listed on a national securities exchange or other public trading platform on or prior to October 15, 2014, then the Series B Preferred stockholders would thereafter have been entitled to elect two members of the board of directors.
	Dividends
	Holders of Series B Preferred were entitled to receive, when and if declared by the board of directors, dividends at the rate of 8% of the original issuance price. Series B Preferred dividends were non-cumulative. In addition to the non-cumulative 8% dividend, the Series B Preferred shares would have also received (on an "as-converted" basis) the same dividend as that declared on common stock shares. The order of preference in the event of a dividend distribution, when and if declared by the board of directors, would have been first made to holders of Series B Preferred, then to holders of Series A Preferred and lastly to holders of common stock. No dividends were ever declared or paid.
	Liquidation Rights
	In the event of a voluntary or involuntary liquidation, dissolution, change in control or winding up of the Company, holders of Series B Preferred were entitled to be paid out first of the assets available at a rate of their original issue price, plus any accrued but unpaid dividends, prior to any payment being made to holders of Series A Preferred or common stock.
	If the assets of the Company available for distribution to stockholders were insufficient to permit payment of the full amount to which each stockholder is entitled, holders of shares of the Series B Preferred would have shared ratably in any distribution of the remaining assets of the Company in proportion to the respective amounts which would otherwise have been payable under the circumstances in the order of liquidation preference.
	After the payment of the full liquidation preference of the preferred stock, the remaining assets, if any, would have been distributed ratably to the holders of preferred stock and common stock on an as-if-converted to common stock basis, provided that if the aggregate amount the holders of the Series B Preferred were entitled to receive exceeded three times the original issue price plus all declared and unpaid dividends thereon (the "Maximum Participation Amount"), such holders would have been entitled to receive the greater of the Maximum Participation Amount or the amount they would have received if all shares of preferred stock had been converted into common stock immediately prior to the liquidation event.
	Because liquidation rights included a change in control, the Series B Preferred was classified within temporary equity. However, since a change in control was not considered probable, no adjustment to the carrying amount was required at any date the Series B Preferred was outstanding.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Stock-Based Compensation
Stock-Based Compensation	13. Stock-Based Compensation
	Private Epirus adopted the 2011 Equity Incentive Plan, as amended ("2011 Plan"), pursuant to which 740,470 shares of common stock were initially authorized for issuance to employees, officers, directors, consultants and advisors of the Private Epirus. The 2011 Plan provides for the grant of incentive stock options, nonstatutory stock options, rights to purchase restricted stock, stock appreciation rights, phantom stock awards and stock units. In connection with the issuance of restricted common stock, the Private Epirus maintains a repurchase right and shares of restricted common stock are released from such repurchase right over a period of time of continued service by the recipient. Recipients of incentive stock options shall be eligible to purchase shares of the Private Epirus common stock at an exercise price equal to no less than the estimated fair value of such stock on the date of grant. In April 2014, the Private Epirus board of directors amended the terms of the 2011 Plan to increase the authorized number of shares of common stock available for issuance under the 2011 Plan from 740,470 to 1,504,752. As described in Note 4, through the Merger, all outstanding and unexercised Private Epirus stock options under the 2011 Plan were assumed by Public Epirus under the 2004 Plan.
	In December 2004, the board of directors and stockholders of Zalicus adopted the 2004 Incentive Plan ("2004 Plan"), which was effective on November 9, 2005. On December 21, 2009, the Compensation Committee of the board of directors authorized an increase in the number of shares of common stock reserved for issuance. As of December 21, 2009, 333,333 shares of common stock were reserved for issuance under the 2004 Plan. The 2004 Plan includes an "evergreen provision" that allows for an annual increase in the number of shares of common stock available for issuance under the 2004 Plan, which annual increase will be added on the first day of each fiscal year from 2011 through 2015, inclusive, and will be equal to the least of (i) 66,667 shares of common stock, (ii) 4% of the outstanding shares on that date or (iii) such lesser amount determined by the board of Directors. The Compensation Committee of the board of directors of Zalicus elected not to increase the number of shares of common stock available for issue under the 2004 Plan in each of the years subsequent to 2009. The 2004 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock and unrestricted stock awards, stock appreciation rights, cash awards, performance awards and restricted stock units. Awards under the 2004 Plan may be granted to employees, directors, consultants and advisors.
	In August 2014, the Company submitted a Form S-8 Registration Statement ("S-8") to the SEC. As reflected in the S-8, the Company amended the 2004 Plan to increase the number of shares available for issuance under the 2004 Plan by 3,000,000 shares of common stock. As of December 31, 2014, the Company had 2,750,384 shares available for issuance.
	Terms of stock award agreements are determined by the board of directors, subject to the provisions provided in the 2004 Plan and the 2011 Plan. Stock options generally vest over a four-year period: 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance and/or market-based vesting provisions. Options are exercisable over a maximum term of 10 years from the grant date.
	For the years ended December 31, 2014 and 2013, the Company recognized stock-based compensation expense of approximately $1,719 and $140, respectively, in connection with its stock-based payment awards. Stock-based compensation expense for the year ended December 31, 2014 includes $355 of postcombination stock-based compensation expense resulting from the acceleration of vesting of previously unvested Zalicus stock options and RSUs, which occurred upon the termination of certain Zalicus employees following the Merger, and $303 related to restricted stock issued to a non-employee.
	As described in Note 4, through the Merger, outstanding Zalicus equity awards remained legally outstanding without change to any agreement terms. Such Zalicus equity awards were assumed to have been exchanged for equity awards of the Company, the accounting acquirer. As a result, the portion of the acquisition-date fair value of the Zalicus equity awards attributable to precombination service to Zalicus, $220, was treated as a component of consideration transferred. See Note 4, "Merger."
	The exchange of the Private Epirus stock options for stock options to purchase Public Epirus Common Stock was treated as a modification of the awards. The modification of the stock options did not result in any incremental compensation expense as the modification did not increase the fair value of the stock options.
	Stock Options
	A summary of stock option activity during the year ended December 31, 2014 is as follows:
		Number of			Weighted-		Weighted-		Aggregate
		Options			Average		Average		Intrinsic
					Exercise		Remaining		Value
					Price		Contractual
							Term (in years)
	Outstanding at December 31, 2013		458,871		$	0.96
	Granted		1,241,576			7.73
	Options assumed through Zalicus merger		134,454			72.02
	Exercised		(98,405	)		0.91
	Cancelled		(83,614	)		36.99
	Outstanding at December 31, 2014		1,652,882		$	10.03		8.9	$	1,628
	Vested and expected to vest at:
	December 31, 2014		1,596,713		$	10.15		8.9	$	1,590
	Exercisable at:
	December 31, 2014		248,134		$	28.14		7.4	$	672
		As of
		December 31,
		2014			2013
	Weighted average grant-date fair value of options granted during the period	$	4.62		$	0.16
	Cash received upon exercise of options	$	90		$	21
	The aggregate intrinsic value in the table above represents the value (the difference between the Company's common stock fair value on December 31, 2014 and the exercise price of the options, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on December 31, 2014. The total intrinsic value of options exercised in the years ended December 31, 2014 and 2013 was $71 and $21, respectively. The total fair value of employee stock options vested in the years ended December 31, 2014 and 2013 was $353 and $208, respectively. As of December 31, 2014, there was $4,909 of total unrecognized stock-based compensation expense related to stock options granted under the plans. The expense is expected to be recognized over a weighted-average period of 3.28 years.
	In determining the exercise prices for options granted, the board of directors considered the fair value of the common stock as of the measurement date. Prior to the Merger, the fair value of the Company's common stock was determined by the board of directors, with input from management, the assistance of a third-party valuation specialist and the guidance outlined in the American Institute of Certified Public Accountants Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation, also known as the Practice Aid, based on a variety of different objective and subjective factors, including valuations prepared by third-party valuation specialists, the Company's financial position, the status of development efforts within the Company, the composition and ability of the current scientific and management teams, the current climate in the marketplace, the illiquid nature of the Company's common stock, the prices of arm's length sales of the Company's Series A Preferred and Series B Preferred, the effect of the rights and preferences of the preferred stockholders, and the likelihood of achieving a liquidity event such as a public offering or sale of the Company. In determining the exercise prices for options granted, the Company's board of directors considered, among other things, the most recent contemporaneous valuation of the Company's common stock and their assessment of additional objective and subjective factors that were relevant as of the grant dates. The dates of the Company's contemporaneous valuations have not always coincided with the dates of stock option grants.
	As of April 1, 2013 and dates prior, the Company determined the fair value of its common stock utilizing the OPM as the type of exit event was unknown as of the measurement dates. Subsequent to April 2013 and prior to the Merger, the Company determined the fair value of its common stock utilizing a hybrid method of the PWERM and OPM as the Company began to consider an IPO or reverse merger as an additional strategy. The hybrid method is consistent with the fair value methodology used for the valuation of the Series A Preferred and Series B Preferred. Refer to Note 11 for a description of the OPM, the PWERM and the hybrid method.
	Subsequent to the Merger, the fair value of the common stock was determined as the closing trading price of the Company's common stock.
	In order to determine the fair value of each employee stock award on the grant date, the Company used the Black-Scholes option-pricing model. During the years ended December 31, 2014 and 2013, respectively, the range of assumptions used in the Black-Scholes pricing model for new grants and grants issued or accelerated in connection with the Merger were as follows:
		Year Ended December 31,
		2014		2013
	Risk-free interest rate	1.80% - 2.09%		1.09% - 1.81%
	Expected volatility	63.96% - 66.07%		66.99%
	Expected term (in years)	6.00		6.00
	Expected dividend yield	0.0%		0.0%
	Risk-Free Interest Rate.    The risk-free interest rate assumption is based on observed interest rates appropriate for the expected term of the stock option grants.
	Expected Volatility.    Due to the Company's limited operating history and lack of Company-specific historical or implied volatility, the expected volatility assumption is based on historical volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology and medical device industries.
	Expected Term.    The expected term represents the period of time that options are expected to be outstanding. The Company utilizes the expected terms from an analysis of peer group companies to support the expected term used in the Black-Scholes model, as it does not believe it has sufficient historical data to support this assumption.
	Expected Dividend Yield.    The expected dividend yield assumption is based on the fact that the Company has never paid cash dividends and has no intention to pay future cash dividends.
	Executive Employment Agreements
	During May and June 2012, the Company and two executives of the Company entered into employment agreements under which the Company granted the executives stock options and agreed to grant the employees additional stock options to maintain the executives' fully diluted equity interest in the Company if the Company issued additional shares as contemplated in the existing Amended Series A Preferred Stock and Warrant Purchase Agreement, dated as of April 3, 2012, subject to continued employment. Pursuant to these clauses in the employment agreements, the Company granted an aggregate of 48,924 stock options in December 2012 and an aggregate of 44,349 stock options in May 2013. The clause expired upon the grant of such additional options.
	In the May 2012 employment agreement, the Company also agreed to grant additional stock options to the executive upon the occurrence of: (1) an Equity Financing, which is defined as the completion of additional preferred stock equity financing(s) by new investors, resulting in the receipt by the Company, on or before the first anniversary of the commencement of the executive's employment, of at least $25,000, at an increase in the price per share of the preferred stock of the Company of at least 10% as compared to the Series A Preferred price per share ($1.00); or (2) a Strategic Partnership Milestone, which is defined as the closing of one or more strategic partnering transactions relating to the development and/or commercialization of one or more of the Company's biosimilar products that provides to the Company: a) at least $25,000 in initial payments and non-contingent milestone payments within 12 months of the effectiveness of the transaction; and b) at least $50,000 in aggregate payments to the Company, in each case, excluding amounts received by the Company for investments in the Company's equity or debt. Upon the occurrence of an Equity Financing, the Company also agreed to grant the executive additional stock options to maintain the executives' fully diluted equity interest in the Company. Upon the occurrence of a Strategic Partnership Milestone, the Company also agreed to grant the executive additional stock options representing an additional 1% equity interest, on a fully diluted basis, in the Company, determined as of the date of the closing of the Strategic Partnership Milestone. The clause in the May 2012 agreement expired in May 2013 and no additional grants of stock options were earned pursuant to this clause.
	Restricted Stock
	In April 2014, the Company granted 53,036 shares of restricted common stock to a non-employee for consulting services. The restricted common stock is subject to certain performance-based vesting conditions under which 25% of the award vested on April 15, 2014 and the remaining 75% would vest following the successful achievement of certain performance milestones and the passage of time. For the 13,259 shares that vested during April 2014, the Company recorded $98 to general and administrative expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2014. In addition, the Company was obligated to pay an upfront fee of $200 and is obligated to pay a monthly consulting fee of $25 for a period of 18 months. The upfront fee of $200 was recorded to general and administrative expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2014.
	In September 2014, an additional 50% of the 53,036 shares of restricted common stock granted in April 2014 vested as a result of certain performance milestones being achieved. Upon such shares' vesting, the Company recorded $185 to general and administrative expense in the consolidated statement of operations and comprehensive loss. The remaining 25% of the 53,036 shares of restricted common stock are expected to vest in September 2015 and are being recognized as expense over this period at their fair value.
	The total of $303 related to restricted stock issued to the non-employee has been recorded to general and administrative expense in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2014.
	A summary of the restricted stock activity during the year ended December 31, 2014 is as follows:
		Restricted			Weighted-
		Stock			Average
					Grant Date
					Fair Value
	Nonvested at December 31, 2013		—		$	—
	Granted		58,560			5.08
	Vested		(45,301	)		5.08
	Cancelled		—			—
	Nonvested at December 31, 2014		13,259		$	5.08
	RSUs
	Prior to the Merger, Zalicus had outstanding 52,777 nonvested RSUs, which were issued to certain employees. In connection with the Merger, pursuant to their original agreements, the Company assumed the RSUs. In connection with the Merger, 25,000 of the RSUs vested immediately. Such shares are included in the number of shares of Public Epirus Common Stock owned by Zalicus stockholders used in the calculation of consideration transferred in the Merger. See Note 4, "Merger," for additional details. Pursuant to their original agreements, the remaining 27,777 RSUs vested upon termination of the employees' following the Merger. Upon the acceleration of vesting of such RSUs, the Company recognized $277 of postcombination stock-based compensation expense, which represents the portion of the acquisition-date fair value of such RSUs that was not attributable to precombination service and is included in the $355 of postcombination stock-based compensation expense resulting from the acceleration of vesting of previously unvested Zalicus stock options and RSUs described above. In addition, the Company recorded a decrease to additional paid in capital in the amount of $297 related to the issuance of common stock upon vesting of the RSU's. A summary of the RSUs activity during the year ended December 31, 2014 is as follows:
	Restricted			Weighted-Average		Weighted-Average		Aggregate
	Stock Units			Grant Date		Remaining		Intrinsic
				Fair Value		Contractual Term		Value
Nonvested at December 31, 2013		—		$	—
Granted		27,777			11.8		—	$	—
Vested		(27,777	)		11.8		—	$	—
Cancelled		—			—
Nonvested at September 30, 2014		—		$	—		—	$	—
The table above does not include the 25,000 Zalicus RSUs that vested immediately in connection with the Merger.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Taxes
Income Taxes	14. Income Taxes
	For the year ended December 31, 2013, the Company realized a deferred tax benefit as a result of the transfer of intellectual property to the Company’s subsidiary, EPIRUS Switzerland GmbH, a Swiss Corporation. However, because the transfer is an intercompany transaction and is eliminated in consolidation, the Company cannot recognize a tax benefit. As a result, the deferred tax benefit of $943 related to the sale of intellectual property was deferred and was presented on the balance sheet as a deferred tax benefit at December 31, 2013. It is being recognized in earnings as the intellectual property asset is amortized in Switzerland over a period of five years, which is the expected tax amortization period for the intellectual property.
	For the year ended December 31, 2014, the Company has recorded an income tax benefit of approximately $43, which is due to a tax benefit of approximately $184 from the amortization of the Company's deferred tax benefit related to the 2013 transfer of intellectual property described above and an approximately $20 tax benefit from the reversal of the estimated alternative minimum tax due for fiscal 2013, offset by approximately $61 of income tax expense in Brazil and approximately $100 of withholding tax in Switzerland. The Company's losses before income taxes primarily consist of domestic losses and foreign losses from its United Kingdom and Switzerland subsidiaries.
	The component of U.S. and foreign loss from continuing operations before income taxes are as follows:
		Year Ended
		December 31,
		2014			2013
	United States	$	(16,149	)	$	(16,601	)
	Foreign		(25,738	)		(4,194	)
	Loss before incomes taxes:	$	(41,887	)	$	(20,795	)
	Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The Company's deferred tax assets and liabilities are comprised of the following:
		As of December 31,
		2014			2013
	Deferred tax assets
	Current assets:
	Accrued Rent	$	208		$	—
	Accrued expenses & other		539			310
	Gross current deferred tax assets	$	747		$	310
	Non-current assets:
	Net operating loss—U.S.	$	11,660		$	7,403
	Research and development credits		573			193
	License/Start-up expenditures		222			242
	Accrued Rent		111			—
	AMT credit		—			20
	Other		147			3
	Capitalized R&D		5,611			—
	Foreign investment tax credit		4,370			—
	Net operating loss—foreign		35,546			1,225
	Gross non-current deferred tax assets	$	58,240		$	9,086
	Gross deferred tax assets	$	58,987		$	9,396
	Deferred tax liabilities
	Non-current:
	Depreciation	$	(14	)	$	—
	Swiss IP amortization		(85	)		—
	Identifiable intangible assets—IPR&D		(2,166	)		—
	Total non-current deferred tax liabilities	$	(2,265	)	$	—
	Gross deferred tax liabilities	$	(2,265	)	$	—
	Gross deferred taxes	$	56,722		$	9,396
	Valuation allowance		(58,888	)		(9,396	)
	Net deferred tax liability	$	(2,166	)	$	—
	The Company has recorded a net deferred tax liability of $2,166 related to in-process research and development as a result of the Merger. It is the Company's position that the in-process research and development is an indefinite-lived intangible asset and is not available as a source of income to support the realization of deferred tax assets. The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based on the Company's history of operating losses, the Company has concluded that it is more likely than not that the benefit of its deferred tax assets will not be realized. The valuation allowance increased during the year ended December 31, 2014, due primarily to the deferred tax assets and tax attributes acquired as a result of the Merger as well as the current year loss generated in the U.S. and Switzerland.
	A reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the financial statements is as follows:
		Year Ended
		December 31,
		2014			2013
	Income tax benefit using U.S. federal statutory rate	$	(14,241	)	$	(7,076	)
	State income taxes, net of federal benefit		(296	)		(784	)
	Other permanent differences		2,985			1,581
	Foreign rate differential		3,836			574
	Tax credits		(223	)		(143	)
	Other items		503			21
	Tax benefit related to the IPR&D transfer		(185	)		—
	Foreign withholding taxes		101			—
	Net change in valuation allowance		7,477			5,827
	Income tax expense (benefit)	$	(43	)	$	—
	As of December 31, 2014 and 2013, the Company had U.S. federal and state net operating loss carryforwards of approximately $32,104 and $20,178, respectively, which may be available to offset future income tax liabilities and expire at various dates through 2034. As of December 31, 2014 and 2013, the Company had foreign net operating loss carryforwards of approximately $144,935 and $6,028, respectively, which may be available to offset future income tax liabilities. The increase in foreign net operating losses is primarily due to the current year loss in Switzerland, as well as the acquisition of Zalicus' Canadian net operating losses. Net operating loss carryforwards generally are unlimited in the United Kingdom and Brazil, while Switzerland allows for a seven year carryforward, and Canada allows for a twenty year carryforward for losses arising in tax years ending after 2005.
	The Company had generated NOL carryforwards from stock-based compensation deductions in excess of expense recognized for financial reporting purposes ("excess tax benefit"). Excess tax benefits are realized when they reduce the taxes payable, as determined by using a "with and without" method, and are credited to additional paid-in capital, rather than a reduction of the income tax provision. As of December 31, 2014 and 2013, the Company had approximately $77 and $0 excess tax benefits, which will be credited to additional paid-in capital when realized.
	As of December 31, 2014 and 2013, the Company had federal research and development tax credit carryforwards of approximately $454 and $152, respectively, available to reduce future tax liabilities which expire at various dates through 2034. As of December 31, 2014 and 2013, the Company had state research and development tax credit carryforwards of approximately $180 and $61, respectively, available to reduce future tax liabilities, certain of the credits have an unlimited carryforward and the remaining credits have a fifteen year carryforward period. The Company also had foreign investment tax credits of approximately $5,283 available to reduce future tax liabilities which expire at various dates through 2028.
	Under the provision of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company acquired a significant amount of federal and state net operating loss carryforward and federal and state research and development credit carryforwards as a result of the Merger. The Company has not performed a full comprehensive Section 382 study to determine any potential loss limitation in the U.S. or a Section 383 study to determine the appropriate amount of tax credit carryforward. A full valuation allowance has been provided against the net operating loss and tax credit carryforwards as of December 31, 2014. If an adjustment is required, the adjustment would be offset by an adjustment to deferred tax assets established for the tax attributes and the valuation allowance or Goodwill for items that are still within the measurement period of purchase accounting.
	The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2014 and 2013, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company's statements of operations and comprehensive loss.
	For all years through December 31, 2014, the Company generated research credits, but has not conducted a study to document the qualified activities. This study may result in an adjustment to the Company's research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company's research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance.
	The Company files income tax returns in the U.S., various state jurisdictions and foreign jurisdictions for its foreign subsidiaries. The federal and state income tax returns are generally subject to tax examinations for the tax years ended 2011 through 2014. The foreign income tax returns are generally subject to tax examinations for the tax years ended 2010 through 2014. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, state or foreign tax authorities to the extent utilized in a future period. There are no currently ongoing or pending examinations in any jurisdiction.
	Final regulations under Internal Revenue Code sections 162(a) and 263(a) on the deduction and capitalization of expenditures related to tangible property were issued by the Internal Revenue Service and the U.S. Treasury Department on September 13, 2013. The final regulations apply to tax years beginning on or after January 1, 2014. The Company has not recorded any adjustments relating to these final regulations, as it believes the impact to be immaterial and any adjustments recorded would be fully offset by the valuation allowance.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2014
Commitments
Commitments	15. Commitments
	On May 15, 2014, the Company amended its March 2013 operating lease for office space in Boston, Massachusetts (the "First Amendment"). The First Amendment provides the Company additional square footage on a new floor of the office. The Company has committed to lease this space for a period of seven years for total cash payments of $3,248. The First Amendment contains rent escalation, rent holiday, and leasehold improvement incentives. Rent escalation and rent holiday are being accounted for as rent expense under the straight-line method. Deferred rent is included in other current and non-current liabilities in the consolidated balance sheet as of December 31, 2014. The Company will record rent expense of approximately $38 per month on a straight-line basis over the effective lease term.
	In connection with the First Amendment, the Company received approximately $477 in leasehold improvement incentives from the landlord. These leasehold improvement incentives are being accounted for as a reduction in rent expense ratably over the lease term. The balance from these leasehold improvement incentives is included in other current liabilities and other non-current liabilities in the consolidated balance sheet. The leasehold improvements are included in property and equipment and are being amortized using the straight-line method over the term of the lease, which is the shorter of the estimated useful lives of the assets and the term of the lease.
	In connection with the Merger, as described in Note 4, the Company assumed Zalicus' Cambridge Massachusetts facility lease. This facility was subleased prior to the completion of the Merger. A liability for the fair value difference between the sublease payments to be received and the future minimum lease payments under the lease agreement of $1,853 and $2,562, respectively, has been recorded in the balance sheet as of December 31, 2014 in other current liabilities and other non-current liabilities, respectively. The original lease and the sublease agreement terminate in January 2017.
	In September 2014, The Company entered into a month-to-month lease for office space in Zug, Switzerland at a rate of approximately $3 per month. In March 2015, the Company entered into a 12 month lease effective April 1, 2015 at a rate of approximately $6 per month. Future minimum lease payments of approximately $84 are included in the table below for office space in Switzerland.
	Future minimum lease payments for all of the Company's existing leases are as follows:
		December 31, 2014
	2015		1,812
	2016		1,719
	2017		567
	2018		472
	2019		480
	2020 and thereafter		817
	Total	$	5,867
	Less: Future sublease payments to be received		(1,854	)
	Net future lease payments	$	4,013
	Rent expense under operating lease agreements amounted to approximately $366 and $236 for the years ended December 31, 2014 and 2013. Rent expense is reported net of sublease income.
	License Agreements
	From time to time, the Company enters into various licensing agreements whereby the Company may use certain technologies in conjunction with its product research and development.
	Catalent Pharma Solutions, LLC
	In January 2009, Moksha8 entered into a cell line sale agreement ("the Cell Line Agreement") with Catalent Pharma Solutions ("Catalent") for the acquisition of a gene expression cell line for BOW015 ("the GPEx Cell Line,") developed by Catalent for Moksha8 pursuant to a separate development and manufacturing agreement dated July 14, 2008. The Cell Line Agreement was assigned to the Company on May 14, 2009, and was amended July 31, 2009 to revise certain payment-related terms. Under the terms of the Cell Line Agreement, the Company exercised an option to acquire all rights in the GPEx Cell Line for development and commercialization of products using the GPEx Cell Line, namely BOW015, subject to certain obligations to make contingent payments to Catalent.
	The Company paid Catalent $0.1 million on execution of the Cell Line Agreement, and paid a further $0.1 million upon exercise of its option to complete the purchase of the GPEx Cell Line. The Company is required to make additional payments to Catalent of up to $0.7 million in the aggregate upon the achievement of certain development and regulatory milestones. In March 2013, the Company paid $0.2 million to Catalent upon the occurrence of certain clinical trial events for BOW015. Pursuant to the agreement, the Company will be obligated to pay an additional $0.5 million upon the achievement of certain development and regulatory milestones. In addition, the Company will be required to pay a contingent sale fee in the form of royalties on worldwide net sales of BOW015 and any other product manufactured using the GPEx Cell Line at a percentage in the very low single digits for a period of 20 years following the first commercial sale of such product, and thereafter at a rate of less than one percent.
	Either the Company or Catalent may terminate the Cell Line Agreement on 60 days' notice for the other party's material breach of the agreement, or for the other party's insolvency, and in the event of Catalent's termination for our material breach of the Cell Line Agreement, the Company's ownership rights in the GPEx Cell Line would revert to Catalent. If the Company terminates the Cell Line Agreement for Catalent's breach, it will retain ownership of the GPEX Cell Line, but their payment obligations to Catalent will terminate.
	Bioceros B.V.
	In April 2013, the Company entered into a license agreement, which the Company refers to as the Bioceros Agreement, with Bioceros B.V., or Bioceros, pursuant to which Bioceros granted the Company a non-exclusive license under its rights in the cell lines and associated intellectual property relating to trastuzumab, bevacizumab and rituximab to permit us to manufacture and commercialize antibody products incorporating the licensed antibodies worldwide, provided that solely with respect to trastuzumab, our licensed territory does not include China, Macau and Hong Kong. Bioceros also granted us the right to receive the tangible embodiments of the cell line and all related know-how for trastuzumab, and an option, subject to payment of certain option fees, to evaluate and receive the tangible embodiments of the cell lines and know-how relating to rituximab and bevacizumab. We exercised our option in relation to bevacizumab in June 2013, and subsequently Bioceros transferred the cell line for bevacizumab to us. The Bioceros Agreement was amended in June 2013 to modify certain payment provisions, and to provide for the performance of certain preclinical services by Bioceros, in each case in relation to bevacizumab.
	In October 2013, we entered into a second license agreement with Bioceros, which we refer to as the Second Bioceros Agreement, on substantially similar terms to those of the April 2013 Bioceros Agreement, pursuant to which Bioceros granted us a non-exclusive license under its rights in the cell line and associated intellectual property relating to adalimumab, to permit us to manufacture and commercialize antibody products incorporating adalimumab worldwide except in Japan. We collectively refer to the initial Bioceros Agreement and the Second Bioceros Agreement as the Bioceros Agreements.
	Under the Bioceros Agreement, we paid to Bioceros an up-front payment of $0.3 million as a license issuance fee applicable to the rights in trastuzumab, and have paid a further $0.4 million in the aggregate as a result of the exercise of our option in June 2013 with respect to bevacizumab. Under the Second Bioceros Agreement, we paid Bioceros an up-front payment of $0.07 million upon execution of the Second Bioceros Agreement, and in the first quarter of 2014, paid a further up-front payment of $0.3 million as a license issuance fee applicable to the rights for adalimumab. Under each of the Bioceros Agreements, we are also required to pay Bioceros a tiered annual license maintenance fee, and will be required to make certain payments to Bioceros upon the achievement of specified regulatory milestones for the products covered by the Bioceros Agreement, totaling up to $1.2 million in the aggregate for all potential products across both agreements. Upon commercialization of products covered by the rights licensed under the Bioceros Agreements, we will be required to pay, on a product-by-product basis, a royalty on net sales at a rate of less than one percent, subject to a specified minimum and maximum annual royalty amount under each agreement. Our obligation to pay royalties to Bioceros under each of the Bioceros Agreements will expire, on a product-by-product basis, on the date that is 10 years following the first commercial sale of each such product. We are required to use commercially reasonable efforts to develop and commercialize products in the licensed territory.
	Absent earlier termination, the Bioceros Agreements will remain in force until the expiration of all payment obligations under the applicable agreement. Either we or Bioceros may terminate either of the Bioceros Agreements on 30 days' notice for the uncured material breach by the other party, or immediately upon the other party's insolvency. We may terminate each of the Bioceros Agreements, on an antibody asset-by-antibody asset basis for any reason on 60 days' notice to Bioceros, and Bioceros may terminate the agreements in the event that we challenge any Bioceros patents included in Bioceros's proprietary antibody production platform.
	In November 2014, the Company entered into a Master Services Agreement with Bioceros ("the Bioceros MSA") pursuant to which Bioceros will develop and transfer to the Company rights in a tocilizumab cell line and associated intellectual property, to permit us to manufacture and commercialize antibody products incorporating tocilizumab. Under the Bioceros MSA, the Company is required to pay Bioceros fees for services related to its creation of our tocilizumab cell line, and will be required to make certain payments to Bioceros upon the achievement of specified regulatory milestones under the agreement. Absent earlier termination, the Bioceros MSA will remain in force until the expiration of all payment obligations under the agreement. Either the Company or Bioceros may terminate the Bioceros MSA on written notice for the uncured material breach by the other party, or immediately upon the other party's insolvency. The Company may terminate the Bioceros MSA for any reason on 60 days' notice to Bioceros. For the year ended December 31, 2014, the Company paid $200 under the Bioceros MSA.

Net_Loss_per_share

Net Loss per share	12 Months Ended
	Dec. 31, 2014
Net Loss per share
Net Loss per share	16. Net Loss Per Share
	The Company computes basic and diluted loss per share using a methodology that gives effect to the impact of outstanding participating securities (the "two-class method"). As the years ended December 31, 2014 and 2013 resulted in net losses, there is no income allocation required under the two-class method or dilution attributed to weighted-average shares outstanding in the calculation of diluted loss per share.
	The following potentially dilutive securities outstanding, prior to the use of the treasury stock method, have been excluded from the computation of diluted weighted-average shares outstanding for the years ended December 31, 2014 and 2013, as they would be anti-dilutive.
		As of December 31,
		2014		2013
	Convertible preferred stock		—		27,248,746
	Settlement of loan agreement		248,093		13,002,222
	Options to purchase common stock		1,652,882		458,871
	Warrants to purchase preferred stock		—		5,267,726
	Warrants to purchase common stock		93,040		—
	Nonvested restricted stock		13,259		—

Employee_Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2014
Employee Benefits.
Employee Benefits	17. Employee Benefits
	Effective January 1, 2013, the Company adopted a defined contribution 401(k) plan for employees who are at least 21 years of age. Employees are eligible to participate in the plan beginning on the first day of the calendar quarter following their date of hire. Under the terms of the plan, employees may make voluntary contributions as a percentage of compensation. The Company has not made any matching contributions since the adoption of the 401(k) plan.

Related_Parties

Related Parties	12 Months Ended
	Dec. 31, 2014
Related Parties.
Related Parties	18. Related Parties
	As discussed in Note 3, in September 2014, the Company entered into an Exclusive License and Collaboration Agreement with Livzon Mabpharm Inc. ("Livzon") for the global development and commercialization of certain antibodies or related biological compounds, including the Company's BOW015, a biosimilar version of infliximab. As of December 31, 2014, Livzon owned approximately 12% of the Company's issued and outstanding common stock. Subsequent to the February 2015 sale of common stock discussed in Note 20, Livzon's ownership decreased to approximately 7%.
	As discussed in Note 3, in September 2014 and October 2014, the Company entered into a series of amendments (collectively, the "amendments") to that certain Revenue and Negotiation Rights Agreement between the Company and Moksha8 Pharmaceuticals, Inc. ("Moksha8"), dated as of December 31, 2010 (the "Moksha8 Revenue Agreement"). Moksha8 is owned in part by Montreux Equity Partners and TPG Capital, which are also shareholders of the Company. As of December 31, 2014, Montreux Equity Partners and TPG Capital each owned approximately 17% of the Company's issued and outstanding common stock. Subsequent to the February 2015 sale of common stock discussed in Note 20, Montreux Equity Partners and TPG's ownership decreased to approximately 5%.

Legal_Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2014
Legal Proceedings
Legal Proceedings	19. Legal Proceedings
	From time to time, the Company is involved in legal proceedings and claims of various types and accounts for these legal proceedings in accordance with ASC Topic 450, "Contingencies." The Company records a liability in its consolidated financial statements for these matters when a loss is considered probable and the amount of loss can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements.
	Zalicus Shareholder Litigation
	Between April 28, 2014 and May 2, 2014, three putative class action lawsuits were filed by purported stockholders of Zalicus in the Business Litigation Session of the Massachusetts Superior Court, Suffolk County, against Zalicus, EB Sub, Inc. the members of Zalicus' board of directors and Private Epirus. Plaintiff has since voluntarily dismissed one of these actions, Civil A. No. 14-1380. The remaining two actions, Civ. A. No. 14-1381 and Civ. A. No. 14-1455, have been consolidated into a single action, In re Zalicus Shareholder Litigation, Lead Civ. A. No. 14-1381 (the "Massachusetts Action"). The Massachusetts Action alleges that the Zalicus board of directors breached its fiduciary duties, and that Private Epirus and EB Sub, Inc. aided and abetted the purported breaches, in connection with the proposed Merger. The Massachusetts Action seeks relief including, among other things, a declaration that the Merger Agreement was entered into in breach of fiduciary duties and is unlawful and unenforceable, an order enjoining defendants from proceeding with the Merger, an order enjoining defendants from consummating the Merger unless and until additional procedures are implemented and all material information in connection with the proposed Merger is disclosed, rescission of the Merger or any terms thereof to the extent implemented (or an award of rescissory damages), compensatory damages and interest, and an award of all costs of the Massachusetts Action, including reasonable attorneys' fees and experts' fees.
	Between May 1, and May 16, 2014, three putative class action lawsuits were filed by purported stockholders of Zalicus in the Court of Chancery of the State of Delaware against Zalicus, Zalicus' directors, Private Epirus and/or EB Sub, Inc., Stein v. Zalicus Inc., et al., No. 9602; Do v. Zalicus, Inc., et al., No. 9636; and Mendlowitz, et al. v. Zalicus Inc., et al., No. 9664 (the "Consolidated Action"). On May 23, 2014, plaintiff Harvey Stein filed a verified amended complaint, and on May 27, 2014, plaintiff Tuan Do filed a verified amended complaint. The Consolidated Action alleged that the Zalicus board of directors breached their fiduciary duties, and Private Epirus and/or EB Sub, Inc. aided and abetted the purported breaches, in connection with the proposed Merger. The Consolidated Action sought relief including, among other things, to preliminarily and permanently enjoin the proposed Merger, to enjoin consummation of the proposed Merger and rescind the Merger if consummated (or to award rescissory damages), an award of compensatory damages, and an award of all costs of the Consolidated Action, including reasonable attorneys' fees and experts' fees.
	On June 6, 2014, plaintiffs' counsel in the Consolidated Action filed a motion seeking to schedule a preliminary injunction hearing in advance of the stockholder vote on the proposed Merger, and seeking expedited discovery in advance of that hearing. Zalicus, Private Epirus, and the individual defendants opposed the motion. After a hearing, on June 13, 2014, the Delaware Court of Chancery denied plaintiffs' motion.
	On October 27, 2014, plaintiffs' counsel in the Massachusetts Action served the Company with a motion for voluntary dismissal and an award of attorney's fees. The motion alleges, as set forth in the consolidated amended complaint filed in the Massachusetts Action on May 21, 2014, that the Form S-4 Registration Statement filed with the SEC on May 8, 2014 contained numerous material misstatements and/or omissions that prevented the Company's shareholders from being able to evaluate the reasonableness of the Merger. The motion further alleges that in the Amended Registration Statement filed on June 4, 2014, the Company supplemented the disclosures and addressed the allegedly material misstatements and omissions contained in the initial Registration Statement, and that the Company did so in response to the claims made in the Massachusetts Action.
	On November 6, 2014, with the Massachusetts Superior Court's entry of a judgment of dismissal, the Massachusetts Action was closed.
	On November 10, 2014, the parties in the Consolidated Action submitted a stipulation and proposed order to dismiss the Consolidated Action and to set a schedule for plaintiffs' counsel's anticipated application for an award of attorney's fees and expenses. On November 12, 2014, the Delaware Court entered an order dismissing the Consolidated Action without prejudice. The Delaware Court retained jurisdiction solely for the purpose of determining plaintiffs' anticipated application for an award of attorneys' fees and reimbursement of expenses.
	After the Consolidated Action was dismissed, the parties commenced and engaged in discussions to resolve the amount of plaintiffs' counsel's application for fees and expenses.
	After negotiations, the parties agreed that the Company will make a combined, global fee and expense payment to counsel in both the Consolidated Action and the Massachusetts Action in the amount of $400,000, a small percentage of which will be paid by the Company's insurer, in full satisfaction of plaintiffs' counsel's claim for attorneys' fees and expenses in the Consolidated Action and the Massachusetts Action, which the parties memorialized in a stipulation dated January 13, 2015. The parties requested that the Delaware Court close the Consolidated Action as a result of the stipulation. The Delaware Court directed that notice of the resolution of plaintiffs' counsel's request for attorneys' fees and expenses be provided to shareholders. The parties have since issued notice to shareholders (including via the Company's filing on a Current Report on March 13, 2015). After expiration of the requisite notice waiting period, the parties will submit to the Delaware Court a proposed order verifying that notice has been provided and providing for the final dismissal and closure of the case. The Company expects, per the parties' agreement, that payment of the agreed-to $400,000 fee and expense amount will be made within ten days of the final dismissal and closure of the Consolidated Action.
	As a result of the above order, The Company has recorded $350 in general and administrative expense in its Consolidated Statement of Operations for the year ended December 31, 2014.
	Reliance Life Sciences Dispute
	In December 2014, Reliance Life Sciences Pvt Ltd, or RLS, exercised its three-year termination for-convenience right with respect to the RLS Agreement, which will cause the agreement to terminate in December 2017. In addition, in March 2015, RLS initiated an arbitration proceeding under the RLS Agreement alleging that the agreement grants RLS exclusive global supply rights for BOW015, that the terms of the Company's collaboration agreements with Fujifilm and Livzon (described above) violate the RLS Agreement, and seeking to terminate the RLS Agreement. The proceeding initiated by RLS seeks a declaratory judgment, but does not seek any monetary damages. The Company disagrees with these allegations, and intends to dispute them through the arbitration proceeding. These collaboration agreements provide, in the case of Fujifilm, for process development and scale up of manufacturing processes for BOW015 to a capacity that may be sufficient to fulfill future requirements for clinical and commercial supply, and, in the case of Livzon, for a grant of rights, under certain circumstances, to supply BOW015 in the future in certain markets. Neither agreement currently includes terms providing for a commercial supply of BOW015. In the absence of any settlement of the dispute by the parties, the Company expects the arbitration proceedings to be completed over the next six months. Following the arbitration proceeding, if the arbitrator were to decide in favor of RLS, the Company would have 30 days to cure the alleged breach, after which time RLS may exercise its right to terminate the agreement immediately. RLS has indicated that it will continue to supply the Company with BOW015 during the arbitration proceeding.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events
Subsequent Events	20. Subsequent Events
	On January 21, 2015, the board of directors of the Company adopted and approved the EPIRUS Biopharmaceuticals, Inc. Severance Plan (the "Severance Plan"), effective January 21, 2015, for employees of the Company at the level of Vice President or above, including the Company's executive officers.
	On January 23, 2015, the Company provided written notice of termination pursuant to the terms of that certain Purchase Agreement dated as of May 8, 2013 (the "Purchase Agreement") between the Company and Lincoln Park Capital Fund, LLC ("LPC") to terminate the Purchase Agreement. The termination was effected on January 26, 2015, one business day following delivery of the notice of termination. The Purchase Agreement provided the Company with an option to terminate the Purchase Agreement for any reason or for no reason by delivering a notice to LPC, and the Company will not incur any early termination penalties in connection with the termination of the Purchase Agreement.
	On February 4, 2015 the Company closed on an underwritten public offering of 9.6 million shares of its common stock, offered at a price of $5.00 per share. Net proceeds to the Company from this offering were approximately $43,555, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. On February 13, 2015, the Company closed on the sale of an additional 958,208 shares of its common stock at a price of $5.00 per share. Net proceeds to the Company from this overallotment were approximately $4,400, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. The Company intends to use the net proceeds of $47,955 from the offering to progress its global BOW015 clinical program and to advance the development of its other product candidates, as well as for general corporate and working capital purposes.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates
	The preparation of the Company's consolidated financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company's consolidated financial statements and accompanying notes. The most significant estimates in the Company's consolidated financial statements relate to the valuation of equity awards, fair value estimates of warrant liabilities, embedded derivatives, purchase price allocations including fair value estimates of intangible assets, estimated useful lives of fixed assets and intangible assets and accruals relating to clinical trials. The Company bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis. The Company's actual results may differ from these estimates under different assumptions or conditions.
	Prior to becoming a public company through the Merger, the Company utilized significant estimates and assumptions in determining the fair value of its common stock. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
	The Company utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation (Practice Aid), to estimate the fair value of its common stock. The methodologies included the probability-weighted expected return method ("PWERM") and option-pricing method ("OPM"). Each valuation methodology included estimates and assumptions that required the Company's judgment. These estimates included assumptions regarding future performance, including the successful completion of preclinical studies and clinical trials and the time to completing an IPO or sale. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
Principles of Consolidation	Principles of Consolidation
	The consolidated financial statements include the accounts of Epirus and its wholly owned subsidiaries: EB Sub, Inc., a Delaware Corporation, Epirus Biopharmaceuticals Ltd., a United Kingdom corporation, Epirus Switzerland GmbH, a Swiss corporation, Epirus Brasil Tecnologia Ltda, a Brazilian corporation and Zalicus Pharmaceuticals Ltd., a Canadian corporation. All significant intercompany balances and transactions have been eliminated in consolidation.
Merger and Exchange Ratio	Merger and Exchange Ratio
	The Merger has been accounted for as a "reverse merger" under the acquisition method of accounting for business combinations with Private Epirus treated as the accounting acquirer of Zalicus. The historical financial statements of Private Epirus have become the historical financial statements of Public Epirus, or the combined company, and are included in this filing labeled Epirus Biopharmaceuticals, Inc. As a result of the Merger, historical common stock, stock options and additional paid-in capital, including share and per share amounts, have been retroactively adjusted to reflect the equity structure of Public Epirus, including the effect of the Merger exchange ratio and the Public Epirus common stock par value of $0.001 per share. See Note 4, "Merger," for additional discussion of the Merger and the exchange ratio.
Reverse Stock Split	Reverse Stock Split
	On July 16, 2014, Public Epirus effected a 1-for-10 reverse stock split of its outstanding common stock, par value $0.001 per share ("Public Epirus Common Stock") (the "Reverse Stock Split"). The accompanying consolidated financial statements and these notes to consolidated financial statements, including the Merger exchange ratio (Note 4) applied to historical Private Epirus common stock and stock options, give retroactive effect to the Reverse Stock Split for all periods presented. The shares of Public Epirus Common Stock retained a par value of $0.001 per share.
Segment and geographic Information	Segment and Geographic Information
	Operating segments are defined as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker ("CODM") or decision-making group in making decisions regarding resource allocation and assessing performance. The Company and the Company's CODM view the Company's operations and manage its business in one operating segment: the development and commercialization of biosimilar monoclonal antibodies for emerging markets. The Company's entire business is managed by a single management team, which reports to the Chief Executive Officer. As of December 31, 2014 and 2013, all of the Company's long-lived assets were held within the United States and Switzerland.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investments with maturities of 90 days or less from the date of purchase to be cash equivalents. As of December 31, 2014 and 2013, all cash and cash equivalents are held in depository accounts at commercial banks. Cash equivalents are reported at fair value.
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk
	Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and restricted cash. The Company maintains its cash and cash equivalent balances in the form of checking and savings accounts with financial institutions that management believes are creditworthy. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company has no financial instruments with off-balance-sheet risk of loss.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The Company determines the fair market values of its financial instruments based on the fair value hierarchy, which is a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the financial instrument based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the financial instrument and are developed based on the information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported or disclosed fair value of the financial instruments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy, and its applicability to the Company's financial assets and liabilities, are described below:
	Level 1 Inputs:    Unadjusted quoted prices in active markets that are accessible at the measurement date of identical, unrestricted assets and liabilities.
	Level 2 Inputs:    Quoted prices for similar assets and liabilities, or inputs that are observable, either directly or indirectly, for substantially the full term through corroboration with observable market data. Level 2 includes investments valued at quoted prices adjusted for legal or contractual restrictions specific to the security.
	Level 3 Inputs:    Pricing inputs are unobservable for the assets and liabilities, that is, inputs that reflect the reporting entity's own assumptions about the assumptions market participants would use in pricing the assets. Level 3 includes private investments that are supported by little or no market activity.
	The fair value hierarchy level is determined by asset class based on the lowest level of significant input. In periods of market inactivity, the observability of prices and inputs may be reduced for certain instruments. This condition could cause an instrument to be reclassified between levels. During the year ended December 31, 2014 and 2013, there were no transfers between levels.
	The Company measures cash equivalents at fair value on a recurring basis. The fair value of cash equivalents is determined based on "Level 1" inputs, which consist of quoted prices in active markets for identical assets. The fair value of the warrant liability was determined based on "Level 3" inputs and utilizing the Black-Scholes option-pricing model (Note 11).
	The fair value of the Company's note is determined using current applicable rates for similar instruments with similar settlement features as of the balance sheet date. The carrying value of the Company's long term debt approximates its fair value as the Company's interest rate is near current market rates for instruments with similar settlement features. The fair value of the Company's note was determined using Level 3 inputs.
Property and Equipment	Property and Equipment
	Property and equipment consists of office furniture, office and computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Property and equipment are recorded at cost and are depreciated when placed into service using the straight-line method of depreciation, based on their estimated useful lives as follows:
	Asset Description	Estimated Useful Lives
	Furniture and fixtures	5 years
	Office and computer equipment	3 years
	Leasehold improvements	Shorter of the useful life or remaining lease term
	Upon retirement or sale, the cost of assets disposed and the related accumulated depreciation is removed from the accounts and any resulting gain or loss is recorded in the consolidated statements of operations.
	The Company evaluates the potential of its long-lived assets for impairment if events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful life of the assets is no longer appropriate. The impairment test is based on a comparison of the undiscounted cash flows expected to be generated from the use of the asset group and its eventual disposition to the carrying value of the asset group. If impairment is indicated, the assets are written down by the amount by which the carrying value of the assets exceeds the related fair value of the assets. Any write-downs are treated as permanent reductions in the carrying value of the assets. No such impairment losses have been recorded through December 31, 2014.
Restricted Cash	Restricted Cash
	Restricted cash represents cash held in depository accounts at financial institutions to collateralize a conditional stand-by letter of credit related to the Company's Boston, Massachusetts, facility lease agreement and the Company's subleased Cambridge, Massachusetts facility. Restricted cash is reported as non-current unless the restrictions are expected to be released in the next 12 months.
In-process Research & Development	In-process Research & Development
	In-process research & development ("IPR&D") represents the fair value assigned to research and development assets that were not fully developed at the date of acquisition. IPR&D acquired in a business combination or recognized from the application of push-down accounting is capitalized on the Company's consolidated balance sheet at its acquisition-date fair value. Until the project is completed, the assets are accounted for as indefinite-lived intangible assets and subject to impairment testing. Upon completion of a project, the carrying value of the related IPR&D is reclassified to intangible assets and is amortized over the estimated useful life of the asset.
	When performing the impairment assessment, the Company first assesses qualitative factors to determine whether it is necessary to recalculate the fair value of its acquired IPR&D. If the Company determines, as a result of the qualitative assessment, that it is more likely than not that the fair value of acquired IPR&D is less than its carrying amount, it calculates the asset's fair value. If the carrying value of the Company's acquired IPR&D exceeds its fair value, then the intangible asset is written down to its fair value. For the year ended December 31, 2014 and 2013, the Company determined that there was no impairment of its IPR&D.
Intangible Assets	Intangible Assets
	The Company amortizes its intangible assets using the straight-line method over its estimated economic life, which is approximately 16.5 years. The Company evaluates the potential impairment of its intangible assets if events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful life of the assets is no longer appropriate. The impairment test is based on a comparison of the undiscounted cash flows expected to be generated from the use of the asset group and its eventual disposition to the carrying value of the asset group. If impairment is indicated, the assets are written down by the amount by which the carrying value of the assets exceeds the related fair value of the assets. Any write-downs are treated as permanent reductions in the carrying value of the assets. For the year ended December 31, 2014 and 2013, the Company determined that there was no impairment of its intangible assets.
Goodwill	Goodwill
	Goodwill represents the difference between the consideration transferred and the fair value of the net assets acquired under the acquisition method of accounting for push-down accounting. Goodwill is not amortized but is evaluated for impairment within the Company's single reporting unit on an annual basis, during the fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of the Company's reporting unit below its carrying amount. When performing the impairment assessment, the accounting standard for testing goodwill for impairment permits a company to first assess the qualitative factors to determine whether the existence of events and circumstances indicates that it is more likely than not that the goodwill is impaired. If the Company believes, as a result of the qualitative assessment, that it is more likely than not that the fair value of goodwill is impaired, the Company must perform the first step of the goodwill impairment test. The Company has determined that goodwill was not impaired as of December 31, 2014 and 2013. To date, the Company has not recognized any impairment charges related to goodwill.
Revenue Recognition	Revenue Recognition
	Multiple-Element Arrangements
	Under the authoritative guidance for revenue recognition related to multiple-element revenue arrangements, each deliverable within a multiple-element revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control. The Company considers a deliverable to have standalone value if the Company sells this item separately or if the item is sold by another vendor or could be resold by the customer. Deliverables not meeting the criteria for being a separate unit of accounting are accounted for on a combined basis.
	In the event the Company enters into a contract in which the deliverables are required to be separated, the Company will allocate arrangement consideration to each deliverable in an arrangement based on its relative selling price. The Company determines selling price using vendor-specific objective evidence ("VSOE"), if it exists; otherwise, the Company uses third-party evidence ("TPE"). If neither VSOE nor TPE of selling price exists for a deliverable, the Company uses estimated selling price ("ESP") to allocate the arrangement consideration. The Company applies appropriate revenue recognition guidance to each unit of accounting.
	Milestones
	Contingent consideration from research and development activities that is earned upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. At the inception of each arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive. This evaluation includes an assessment of whether: (a) the consideration is commensurate with either (1) the entity's performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity's performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
	Royalty Revenue
	Under certain license agreements to which the Company is a party, the Company receives royalty payments based upon its licensees' net sales of products. Generally, under these agreements, the Company receives royalty payments from licensees approximately one quarter in arrears after the licensee has sold the income generating product or products. The Company recognizes royalty revenues when it can reliably estimate such amounts and collectability is reasonably assured. As such, the Company generally recognizes royalty revenues in the quarter reported to it by its licensees. Therefore, royalty revenues are recognized one quarter in arrears from the quarter in which sales by its licensees occurred. Under this accounting policy, the royalty revenues the Company recognizes are not based upon estimates and are typically reported in the same period in which the Company receives payment from its licensees.
Deferred Revenue	Deferred Revenue
	Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized within 12 months from the balance sheet date are classified as long-term deferred revenue.
Deferred Rent	Deferred Rent
	Deferred rent, included within other non-current liabilities, net of the current portion recorded in accrued expenses in the consolidated balance sheet, consists of the difference between cash payments and the recognition of rent expense on a straight-line basis for the facilities the Company occupies. The Company's lease for its Boston, Massachusetts, facility provides for a rent-free period as well as fixed increases in minimum annual rental payments. The total amount of rental payments due over the lease term is being charged to rent expense ratably over the life of the lease.
Other Liabilities	Other Liabilities
	In conjunction with the Merger, as discussed in Note 4, the Company assumed a sublease liability for Zalicus' Cambridge, Massachusetts facility, which is included within other non-current liabilities, net of the current portion recorded in other current liabilities on the consolidated balance sheet. The liability represents the fair value of the difference between the total sublease payments to be received by the Company and the total payment obligation for the Company per the lease agreement.
	The Company has an operating lease for office space in Boston, Massachusetts. In connection with this lease, the Company and its third party lessor agreed that the lessor would pay for certain leasehold improvements on behalf of the Company. These leasehold improvements are accounted for as a lease incentive obligation, which is recorded in other non-current liabilities, net of the current portion recorded in other current liabilities. This liability is being amortized over the life of the lease and as a reduction to rent expense.
Organizational Costs	Organizational Costs
	All organizational costs are expensed as incurred.
Research and Development Costs	Research and Development Costs
	Research and development costs are charged to expense as incurred in performing research and development activities. The costs include employee compensation, facilities and overhead, clinical study and related clinical manufacturing costs, regulatory and other related costs. Nonrefundable advanced payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.
	Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be.
Stock-Based Compensation	Stock-Based Compensation
	The Company accounts for grants of stock options and restricted stock based on their grant date fair value and recognizes compensation expense over the award's vesting period. The Company estimates the fair value of stock options as of the date of grant using the Black-Scholes option-pricing model and restricted stock based on the fair value of the underlying common stock, which is determined as the closing trading price of the Company's common stock subsequent to the Merger, in which the Company's common stock became publicly traded, and was determined by management prior to the Merger (Note 13).
	Stock-based compensation expense represents the cost of the grant date fair value of employee stock option grants recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis, net of estimated forfeitures. The expense is adjusted for actual forfeitures at the end of each reporting period. Stock-based compensation expense recognized in the consolidated financial statements is based on awards that are ultimately expected to vest.
	Stock-based awards issued to nonemployees are accounted for based on the fair value of such services received or of the equity instruments issued, whichever is more reliably measured. Awards are revalued at each reporting date and upon vesting and are expensed on a straight-line basis over the vesting period.
Income Taxes	Income Taxes
	The Company accounts for income taxes under the liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in operations in the period that includes the enactment date.
	The Company recognizes net deferred tax assets through the recording of a valuation allowance to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future, in excess of its net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.
	The Company records uncertain tax positions on the basis of a two-step process whereby: (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Net Loss Per Share	Net Loss Per Share
	Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. During periods of income, the Company allocates participating securities a proportional share of income determined by dividing total weighted average participating securities by the sum of the total weighted average common shares and participating securities (the "two-class method"). The Company's convertible preferred stock, which was exchanged for Public Epirus Common Stock in the Merger, participated in any dividends declared by the Company and were therefore considered to be participating securities. Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods of loss, the Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. Diluted net loss per share attributable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, common stock equivalents have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented.
Comprehensive Loss	Comprehensive Loss
	Comprehensive loss is the change in equity of a company during a period from transactions and other events and circumstances, excluding transactions resulting from investments by owners and distributions to owners. The Company's net loss equals comprehensive loss for all periods presented.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	Revenue Recognition
	In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in Accounting Standards Codification Topic 605, Revenue Recognition, and creates a new Topic 606, Revenue from Contracts with Customers. This guidance is effective for fiscal years beginning after December 15, 2016, with early adoption not permitted. Two adoption methods are permitted: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. The Company has not yet determined which adoption method it will utilize or the effect that the adoption of this guidance will have on its consolidated financial statements.
	Discontinued Operations and Disposals
	In April 2014, the FASB issued ASU No. 2014-8, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-8"). ASU 2014-8 changes the criteria for determining which disposals can be presented as discontinued operations and modifies related disclosure requirements. Under the new guidance, a discontinued operation is defined as a disposal of a component or group of components that is disposed of or is classified as held for sale and represents a strategic shift that has a major effect on an entity's operations and financial results. This accounting guidance applies prospectively to new disposals and new classifications of disposal groups as held for sale. The guidance is effective for fiscal years beginning after December 15, 2014.
	Development Stage Entity
	In June 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation ("ASU 2014-10"). ASU 2014-10 removes all incremental financial reporting requirements from GAAP for development stage entities, including the removal of Topic 915 from the FASB Accounting Standards Codification ("ASC"). In addition, the update adds an example disclosure in Risks and Uncertainties, ASC Topic 275, to illustrate one way that an entity that has not begun planned principal operations could provide information about the risks and uncertainties related to the company's current activities and removes an exception provided to development stage entities in Consolidations, ASC Topic 810, for determining whether an entity is a variable interest entity—which may change the consolidation analysis, consolidation decision, and disclosure requirements for a company that has an interest in a company in the development stage. ASU 2014-10 is effective for fiscal years beginning after December 15, 2014 with the revised consolidation standards effective for fiscal years beginning after December 15, 2016. Early adoption is permitted. The Company early adopted the guidance and eliminated the presentation and disclosure requirements of ASC Topic 915 during the three months ending June 30, 2014 and the year ended December 31, 2014.
	Going Concern
	In August 2014, the FASB issued ASC Update No. 2014-15, Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern (Subtopic 205-40) ("ASU 2014-14"). ASU 2014-15 requires management to assess an entity's ability to continue as a going concern every reporting period, and provide certain disclosures if management has substantial doubt about the entities ability to operate as a going concern, or an express statement if not, by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The adoption of ASU 2014-15 is not expected to have an impact on the Company's financial position or results of operations.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Schedule of Property and equipment estimated useful lives
	Asset Description	Estimated Useful Lives
	Furniture and fixtures	5 years
	Office and computer equipment	3 years
	Leasehold improvements	Shorter of the useful life or remaining lease term

Merger_Tables

Merger (Tables)	12 Months Ended
	Dec. 31, 2014
Merger
Schedule of acquisition-date fair value of consideration transferred
	Number of shares of Public Epirus Common Stock owned by Zalicus stockholders(1)			2,635,871
	Multiplied by the price per share of Public Epirus Common Stock(2)		$	11.80
	Fair value of shares of Public Epirus Common Stock owned by Zalicus stockholders		$	31,104
	Acquisition-date fair value of assumed Zalicus equity awards attributable to precombination services(3)		$	220
	Total consideration transferred		$	31,324
	-1	The stock transferred in the table above is comprised of 2,610,871 common shares outstanding at the time of the Merger plus 25,000 restricted stock units (RSUs) that vested immediately upon the closing of the Merger. The fair value of shares of Public Epirus Common Stock owned by Zalicus shareholders of $31,104 includes approximately $1 related to fractional shares resulting from the Reverse Stock Split.
	-2	The shares outstanding are multiplied by the closing trading price of Public Epirus Common Stock as of the Merger date.
	-3	Consideration transferred includes approximately $220 of Zalicus equity awards assumed and deemed attributable to precombination services to Zalicus. This amount excludes approximately $355 of acquisition-date fair value attributable to postcombination service, which was recorded to reflect the acceleration of nonvested equity awards of Zalicus upon the termination of certain Zalicus employees after the Merger. The Company recognized the $355 as stock-based compensation expense in the postcombination period ended December 31, 2014 (Note 13). The fair value of the equity awards at July 15, 2014 was determined using a Black-Scholes option-pricing model with the following ranges of assumptions: exercise price of $14.70 per share to $591.00 per share; underlying stock value of $11.80 per share; expected volatility of 66.02%; expected term of 0.1 years to 6.0 years; and risk-free interest rate of 1.91%.
Summary of estimated fair values of the assets acquired and liabilities assumed at date of acquisition
			July 15, 2014
	Cash and cash equivalents		$	13,756
	In-process research and development			5,500
	Goodwill			14,864
	Restricted cash			1,850
	Other assets			253
	Total assets acquired			36,223
	Accounts payable			(1,584	)
	Accrued expenses			(381	)
	Other current liabilities			(376	)
	Other liabilities			(391	)
	Deferred tax liabilities			(2,166	)
	Total liabilities assumed			(4,899	)
	Total net assets acquired		$	31,324
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013
			Year Ended
			December 31,
			2014			2013
	Total revenues, net		$	2,739		$	14,731
	Net loss		$	(32,410	)	$	(69,630	)

Prepaid_Expenses_and_Other_Cur1

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Prepaid Expenses and Other Current Assets.
Schedule of prepaid expenses and other current assets
		As of
		December 31,
		2014		2013
	Prepaid clinical expenses	$	5	$	599
	Prepaid manufacturing expenses		457		194
	Prepaid other expenses		633		85
	Other current assets		461		10
	Total prepaid and other current assets	$	1,556	$	888

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property and Equipment, Net.
Components of Property and Equipment
		As of
		December 31,
		2014			2013
	Computer equipment	$	173		$	70
	Furniture and fixtures		116			49
	Leasehold improvements		504			10
	Total property and equipment		793			129
	Less: accumulated deprecation		(89	)		(39	)
	Property and equipment, net	$	704		$	90

Goodwill_IPRD_and_Intangible_A1

Goodwill, IPR&D and Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill, IPR&D and Intangible Assets, Net
Schedule of Changes in Goodwill	Schedule of Changes in Goodwill
	Balance at December 31, 2013	$	1,499
	Goodwill related to Merger		14,864
	Balance at December 31, 2014	$	16,363
Schedule of Intangible Assets
		December 31, 2014			December 31, 2013
	Intangible assets	$	3,687		$	—
			3,687			—
	Less: accumulated amortization—intangible assets		(82	)		—
	Intangible assets, net	$	3,605		$	—
Schedule of estimated aggregate amortization of intangible assets
		December 31, 2014
	2015	$	225
	2016		225
	2017		225
	2018		225
	2019		225
	2020 and thereafter		2,480
	Total	$	3,605

Accrued_Expenses1

Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Accrued Expenses
Components of Accrued expenses
		December 31, 2014		December 31, 2013
	Accrued professional fees	$	1,822	$	544
	Accrued compensation		1,244		725
	Accrued manufacturing expense		813		380
	Accrued clinical expense		63		286
	Accrued interest expense		71		502
	Other		88		55
	Total accrued expenses	$	4,101	$	2,492

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt
Schedule of future principal payment	Future principal payments, which exclude the 3% end of term charge, in connection with the 2014 Loan Agreement, as of December 31, 2014 are as follows:
		Principal
		Payments
	2015	$	—
	2016		1,851
	2017		2,971
	2018		2,678
	Total	$	7,500

Warrants_Tables

Warrants (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of warrants to purchase stock outstanding
		As of December 31, 2013
		Number of		Exercise		Fair Value at
		Shares		Price Per		December 31,
		Underlying		Share		2013
		Warrant
	Series A Preferred		462,399	$	1.00	$	311
	Series A Preferred		4,805,327	$	0.01	$	5,532
Common stock
Schedule of warrants to purchase stock outstanding
		As of December 31, 2014
		Number of		Exercise
		Shares		Price Per
		Underlying		Share
		Warrants
	Common Stock		1,379	$	0.08
	Common Stock		64,194	$	7.01
	Common Stock		20,616	$	7.55
	Common Stock		3,737	$	68.40
	Common Stock		1,079	$	83.40
	Common Stock		1,887	$	135.00
	Common Stock		148	$	405.00

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Schedule of financial assets and financial liabilities measured at fair value on a recurring basis
			As of December 31, 2014
			Level 1			Level 2		Level 3		Total
	Assets
	Cash and cash equivalents		$	21,462		$	—	$	—	$	21,462
			$	21,462		$	—	$	—	$	21,462
			As of December 31, 2013
			Level 1			Level 2		Level 3		Total
	Assets
	Cash and cash equivalents		$	1,798		$	—			$	1,798
			$	1,798		$	—	$	—	$	1,798
	Liabilities
	Warrant liability		$	—		$	—	$	5,843	$	5,843
			$	—		$	—	$	5,843	$	5,843
Quantitative information about the fair value measurements used in the valuations of the warrant liability and embedded compounded derivative:
			Valuation Assumptions as of
			June 30, 2014		April 15, 2014		March 31, 2014	March 10, 2014
	Hybrid approach
	Discount rate		*		21% to 30%		25% to 30%	25% to 30%
	Probability weighted value for common stock		20% to 80%		30% to 70%		45% to 55%	45% to 55%
	Discount for lack of marketability		5% to 30%		11% to 34%		10% to 28%	10% to 28%
	With and Without approach
	Probability of occurrence of certain events		**		0% to 100%		5% to 50%	5% to 50%
	Market yield		**		25%		25%	25%
	Recovery rate		**		31% to 47%		31% to 47%	31% to 47%
	*	Discount rate not used as DCF was not calculated.
	**	No compound derivative to fair value at June 30, 2014.
Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Schedule of changes in the fair value of liabilities determined using Level 3 inputs
			December 31,
			2014
	Balance at December 31, 2013		$	5,843
	Warrant issuance			1,171
	Change in fair value			222
	Warrant exercises			(7,069	)
	Reclassification to equity			(167	)
	Balance at December 31, 2014		$	—
Embedded Derivative Financial Instruments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Schedule of changes in the fair value of liabilities determined using Level 3 inputs
			December 31,
			2014
	Balance at December 31, 2013		$	—
	Embedded compound derivative			23
	Change in fair value			—
	Derecognition of embedded compound derivative			(23	)
	Balance at December 31, 2014		$	—

Capital_Stock_Tables

Capital Stock ( Tables)	12 Months Ended
	Dec. 31, 2014
Capital Stock
Schedule of common stock shares reserved for future issuances
		As of December 31,
		2014		2013
	Conversion of Preferred Stock		—		27,248,746
	Stock-based compensation awards		4,403,266		740,470
	Warrants to purchase preferred stock		—		5,267,726
	Warrants to purchase common stock		93,040		—
	Settlement of long-term debt		248,093		—
	Total		4,744,400		33,256,942

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Stock-Based Compensation
Summary of stock option activity
		Number of			Weighted-		Weighted-		Aggregate
		Options			Average		Average		Intrinsic
					Exercise		Remaining		Value
					Price		Contractual
							Term (in years)
	Outstanding at December 31, 2013		458,871		$	0.96
	Granted		1,241,576			7.73
	Options assumed through Zalicus merger		134,454			72.02
	Exercised		(98,405	)		0.91
	Cancelled		(83,614	)		36.99
	Outstanding at December 31, 2014		1,652,882		$	10.03		8.9	$	1,628
	Vested and expected to vest at:
	December 31, 2014		1,596,713		$	10.15		8.9	$	1,590
	Exercisable at:
	December 31, 2014		248,134		$	28.14		7.4	$	672
		As of
		December 31,
		2014			2013
	Weighted average grant-date fair value of options granted during the period	$	4.62		$	0.16
	Cash received upon exercise of options	$	90		$	21
Summary of weighted-average assumptions used in the Black-Scholes pricing model
		Year Ended December 31,
		2014		2013
	Risk-free interest rate	1.80% - 2.09%		1.09% - 1.81%
	Expected volatility	63.96% - 66.07%		66.99%
	Expected term (in years)	6.00		6.00
	Expected dividend yield	0.0%		0.0%
Summary of restricted stock activity
		Restricted			Weighted-
		Stock			Average
					Grant Date
					Fair Value
	Nonvested at December 31, 2013		—		$	—
	Granted		58,560			5.08
	Vested		(45,301	)		5.08
	Cancelled		—			—
	Nonvested at December 31, 2014		13,259		$	5.08
Summary of RSUs activity
		Restricted			Weighted-Average		Weighted-Average		Aggregate
		Stock Units			Grant Date		Remaining		Intrinsic
					Fair Value		Contractual Term		Value
	Nonvested at December 31, 2013		—		$	—
	Granted		27,777			11.8		—	$	—
	Vested		(27,777	)		11.8		—	$	—
	Cancelled		—			—
	Nonvested at September 30, 2014		—		$	—		—	$	—

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Taxes
Schedule of loss from continuing operations before income taxes
		Year Ended
		December 31,
		2014			2013
	United States	$	(16,149	)	$	(16,601	)
	Foreign		(25,738	)		(4,194	)
	Loss before incomes taxes:	$	(41,887	)	$	(20,795	)
Summary of Deferred Taxes
		As of December 31,
		2014			2013
	Deferred tax assets
	Current assets:
	Accrued Rent	$	208		$	—
	Accrued expenses & other		539			310
	Gross current deferred tax assets	$	747		$	310
	Non-current assets:
	Net operating loss—U.S.	$	11,660		$	7,403
	Research and development credits		573			193
	License/Start-up expenditures		222			242
	Accrued Rent		111			—
	AMT credit		—			20
	Other		147			3
	Capitalized R&D		5,611			—
	Foreign investment tax credit		4,370			—
	Net operating loss—foreign		35,546			1,225
	Gross non-current deferred tax assets	$	58,240		$	9,086
	Gross deferred tax assets	$	58,987		$	9,396
	Deferred tax liabilities
	Non-current:
	Depreciation	$	(14	)	$	—
	Swiss IP amortization		(85	)		—
	Identifiable intangible assets—IPR&D		(2,166	)		—
	Total non-current deferred tax liabilities	$	(2,265	)	$	—
	Gross deferred tax liabilities	$	(2,265	)	$	—
	Gross deferred taxes	$	56,722		$	9,396
	Valuation allowance		(58,888	)		(9,396	)
	Net deferred tax liability	$	(2,166	)	$	—
Summary of the reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes
		Year Ended
		December 31,
		2014			2013
	Income tax benefit using U.S. federal statutory rate	$	(14,241	)	$	(7,076	)
	State income taxes, net of federal benefit		(296	)		(784	)
	Other permanent differences		2,985			1,581
	Foreign rate differential		3,836			574
	Tax credits		(223	)		(143	)
	Other items		503			21
	Tax benefit related to the IPR&D transfer		(185	)		—
	Foreign withholding taxes		101			—
	Net change in valuation allowance		7,477			5,827
	Income tax expense (benefit)	$	(43	)	$	—

Commitments_Tables

Commitments (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments
Schedule of Future Minimum Lease Payments under Operating Leases
		December 31, 2014
	2015		1,812
	2016		1,719
	2017		567
	2018		472
	2019		480
	2020 and thereafter		817
	Total	$	5,867
	Less: Future sublease payments to be received		(1,854	)
	Net future lease payments	$	4,013

Net_Loss_per_share_Tables

Net Loss per share (Tables)	12 Months Ended
	Dec. 31, 2014
Net Loss per share
Summary of potentially dilutive securities outstanding excluded from the computation of diluted weighted-average shares outstanding
		As of December 31,
		2014		2013
	Convertible preferred stock		—		27,248,746
	Settlement of loan agreement		248,093		13,002,222
	Options to purchase common stock		1,652,882		458,871
	Warrants to purchase preferred stock		—		5,267,726
	Warrants to purchase common stock		93,040		—
	Nonvested restricted stock		13,259		—

Organization_Details

Organization (Details) (USD $)	1 Months Ended	12 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Aug. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Feb. 04, 2015	Dec. 31, 2012
Business Acquisition [Line Items]
Compensation for transfer of intellectual property.	$10,080
Cash and cash equivalents		21,462	1,798		2,234
Accumulated deficit		-86,571	-44,727
Net loss		-41,844	-20,795
Proceeds available from the second tranche		7,500
Subsequent event
Business Acquisition [Line Items]
Net proceeds from its equity offering				$47,955

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended		0 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Jul. 16, 2014
	segment
	instrument
In-Process R&D
Impairment charge of IPR&D	$0
Intangible Assets
Intangible asset, useful life	16 years 6 months
Property and Equipment
Impairment losses	0
Reverse stock split
Common stock (par value)	$0.00	$0.00
Fair Value of Financial Instruments
Asset transfers between Levels	$0	$0
Segment Information
Number of operating segments	1
Concentrations of Credit Risk and Off-Balance Sheet Risk
Financial instruments held	0
Common Class A
Reverse stock split
Reverse stock split conversion ratio			0.1
Common stock (par value)			$0.00
Furniture And Fixtures
Property and Equipment
Estimated useful life	5 years
Office and computer equipment
Property and Equipment
Estimated useful life	3 years

Business_Agreements_Details

Business Agreements (Details) (USD $)	12 Months Ended	1 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Nov. 30, 2014	Mar. 31, 2014	Jan. 31, 2014	Sep. 30, 2013	Dec. 31, 2013	Oct. 31, 2014
		item
Business Agreements
Intangible asset	$5,500						$2,437
BOW015
Business Agreements
Upfront payment received	250
Ranbaxy Laboratories Limited [Member]
Business Agreements
Damages payable to Ranbaxy on breach of license agreement	500
Moksha8 Pharmaceuticals Inc
Business Agreements
Ownership percentage	17.00%
Moksha8 Pharmaceuticals Inc | BOW015
Business Agreements
Payment to terminate payment obligations under agreement		1,500						1,400
Number of payment installments to terminate obligations under agreement		2
Accrued royalty settlement		1,500
Accrued royalty obligations								150
Accrued liability								1,400
Intangible asset		1,250						1,250
Royalty Bearing And Non Transferable License Agreement [Member] | BOW015
Business Agreements
Number of units of accounting for recognition of revenue of deliverables	1
Royalty Bearing And Non Transferable License Agreement [Member] | Ranbaxy Laboratories Limited [Member] | BOW015
Business Agreements
Upfront payment received					500
Maximum payments to be received for achievement of certain development and regulatory approval milestones					1,000
Maximum payments to be received for achievement of certain sales milestones					10,000
Billings to Ranbaxy	1,250	125	250	250	125
Deferred revenue over the remaining term of license agreement			500
Proceeds received from Ranbaxy	1,000
Amount due from Ranbaxy	250
Orygen Heads Of Agreement [Member] | Orygen Biotechnology [Member] | BOW015
Business Agreements
Upfront payment received						250
Supply Agreement [Member] | Ranbaxy Laboratories Limited [Member] | BOW015
Business Agreements
Term of agreement		10 years
Number of automatic renewals		5
Automatic renewal period		2 years
Exclusive License And Collaboration Agreement [Member] | Ranbaxy Laboratories Limited [Member] | BOW015
Business Agreements
Maximum additional compounds subject to exclusive, royalty-bearing licenses	4
Exclusive License And Collaboration Agreement [Member] | Livzon Mabpharm Inc
Business Agreements
Revenue recognized from licensing agreement	2,500
Term of agreement	20 years	20 years
Payments to be received for achievement of specified regulatory milestones		$2,500

Merger_Details

Merger (Details) (USD $)	0 Months Ended	3 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Jul. 15, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Jul. 15, 2014	Jul. 14, 2014
Acquisition-date fair value of the consideration transferred
Stock-based compensation expense			$1,719	$140
Estimated fair values of the assets acquired and liabilities assumed at the date of acquisition:
Goodwill			16,363	1,499
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Net loss			-41,844	-20,795
Zalicus
Acquisition-date fair value of the consideration transferred
Number of Public Epirus Common Stock owned by Zalicus stockholders (1)	2,635,871
Multiplied by the price per share of Public Epirus Common Stock (2) (in dollars per share)	$11.80				$11.80
Fair value of shares of Public Epirus Common Stock owned by Zalicus stockholders	31,104
Acquisition-date fair value of assumed Zalicus equity awards attributable to precombination services (3)	220
Total consideration transferred	31,324
Amount of fractional shares resulting from Reverse Stock Split included as consideration	1
Stock-based compensation expense		355
Exercise price (in dollars per share)	$591				$591
Share price (in dollars per share)	$11.80				$11.80
Volatility rate	66.02%
Risk-free interest rate	1.91%
Estimated fair values of the assets acquired and liabilities assumed at the date of acquisition:
Cash and cash equivalents						13,756
In-process research and development						5,500
Goodwill						14,864
Restricted cash						1,850
Other assets						253
Total assets acquired						36,223
Accounts payable						-1,584
Accrued expenses						-381
Other current liabilities						-376
Other liabilities						-391
Deferred tax liabilities						-2,166
Total liabilities assumed						-4,899
Total net assets acquired						31,324
Other liabilities of accrued expenses and other liabilities relates to a sublease liability	376
Effective tax rate	39.39%
Operating loss from date of acquisition included in financial statements		25
Business Combination, Acquisition Related Costs			5,779
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Total revenues, net			2,739	14,731
Net loss			-32,410	-69,630
Zalicus | Transaction Costs
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Net loss			8,673
Zalicus | stock-based compensation expense
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Net loss			355
Zalicus | severance agreements
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Net loss			1,980
Zalicus | other expense related to the change in the fair values of liability-classified warrants
Supplemental unaudited pro forma information as if acquisition had occurred on January 1, 2013:
Net loss			$222	$789
Zalicus | In Process Research and Development
Estimated fair values of the assets acquired and liabilities assumed at the date of acquisition:
Discount rate (as a percent)	13.10%
Zalicus | Minimum
Acquisition-date fair value of the consideration transferred
Exercise price (in dollars per share)	$14.70				$14.70
Expected term	1 month 6 days
Zalicus | Maximum
Acquisition-date fair value of the consideration transferred
Expected term	6 years
Zalicus | Common stock
Acquisition-date fair value of the consideration transferred
Number of Public Epirus Common Stock owned by Zalicus stockholders (1)	2,610,871
Zalicus | RestrictedStockUnitsVestedUponClosingOfBusinessCombinationMember
Acquisition-date fair value of the consideration transferred
Number of Public Epirus Common Stock owned by Zalicus stockholders (1)	25,000
Zalicus | Common Class A
Merger
Number of shares of acquiree received for each share of acquirer exchanged	0.13259
Aggregate number of acquiree shares received for acquirer shares	10,288,180
Number of acquiree shares received for future issuance upon exercise of stock options	1,152,042
Number of acquiree shares received for future issuance upon exercise of warrants	21,996

Prepaid_Expenses_and_Other_Cur2

Prepaid Expenses and Other Current Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Prepaid Expenses and Other Current Assets.
Prepaid clinical expenses	$5	$599
Prepaid manufacturing expenses	457	194
Prepaid other expenses	633	85
Other current assets	461	10
Total prepaid and other current assets	$1,556	$888

Property_and_Equipment_Net_Det

Property and Equipment, Net (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment
Property and equipment, Gross	$793	$129
Less: accumulated depreciation	-89	-39
Property, Plant and Equipment, Net	704	90
Depreciation expense	165	31
Computer equipment
Property and Equipment
Property and equipment, Gross	173	70
Furniture And Fixtures
Property and Equipment
Property and equipment, Gross	116	49
Leasehold Improvements
Property and Equipment
Property and equipment, Gross	$504	$10

Goodwill_IPRD_and_Intangible_A2

Goodwill, IPR&D and Intangible Assets, Net (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Change in Goodwill
Goodwill, Beginning Balance	$1,499
Goodwill related to Merger	14,864
Goodwill, Ending Balance	16,363
Accumulated goodwill impairment losses	$0

Goodwill_IPRD_and_Intangible_A3

Goodwill, IPR&D and Intangible Assets, Net (Details 2) (USD $)	12 Months Ended	1 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Jul. 31, 2014	Dec. 31, 2013	Oct. 31, 2014	Sep. 30, 2014
Intangible Assets
Intangible asset, useful life	16 years 6 months
Intangible asset	$5,500		$2,437
Intangible assets, net of accumulated amortization
Intangible assets, gross	3,687
Less: accumulated amortization--intangible assets	-82
Intangible assets, net	3,605
In Process Research and Development
Intangible Assets
Reclassification from indefinite lived asset to finite lived asset		2,437
Intangible asset, useful life	16 years 6 months
Intangible assets, net of accumulated amortization
Amortization expense	82		0
BOW015 | In Process Research and Development
Intangible Assets
Intangible asset	0		2,374
BOW015 | Moksha8 Pharmaceuticals Inc
Intangible Assets
Payment to terminate payment obligations under agreement				1,400	1,500
Intangible asset				1,250	1,250
Z944 | In Process Research and Development
Intangible assets, net of accumulated amortization
Intangible assets, net	$5,500

Goodwill_IPRD_and_Intangible_A4

Goodwill, IPR&D and Intangible Assets, Net (Details 3) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Estimated future amortization expense related to finite-lived purchased intangible assets
2015	$225
2016	225
2017	225
2018	225
2019	225
2020 and thereafter	2,480
Total	$3,605

Accrued_Expenses2

Accrued Expenses (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Expenses
Accrued professional fees	$1,822	$544
Accrued compensation	1,244	725
Accrued manufacturing expense	813	380
Accrued clinical expense	63	286
Accrued interest expense	71	502
Other	88	55
Total accrued expenses	$4,101	$2,492

Debt_Details

Debt (Details) (USD $)	12 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended					9 Months Ended	0 Months Ended
	Dec. 31, 2014	Apr. 15, 2014	Apr. 30, 2014	Mar. 10, 2014	Oct. 31, 2013	Oct. 01, 2013	Jul. 08, 2013	Mar. 13, 2013	Sep. 30, 2014	Sep. 30, 2014	Oct. 01, 2014	Dec. 31, 2013	Mar. 31, 2014
								item		loan
										item
Convertible debt
Fair value of warrants												$5,843,000
Carrying value												12,500,000
Gain on extinguishment	-22,000
Outstanding borrowings	7,500,000
long-term debt obligation	7,282,000
Debt discount	218,000
Amortization of the debt discount included in interest expense	14,000
Series A Convertible Preferred Stock
Convertible debt
Number of shares issuable upon exercise of warrants			5,101,816									2,499,996
Exercise price of warrants (in dollars per share)												$0.01
Series B Convertible Preferred Stock
Convertible debt
Number of shares issuable upon exercise of warrants			787,402
Number of shares issued upon conversion of debt		3,947,363	3,947,363
Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01 | Series B Convertible Preferred Stock
Convertible debt
Number of shares issuable upon exercise of warrants		787,402											787,402
Exercise price of warrants (in dollars per share)		0.01
Convertible Debt Issued 2013
Convertible debt
Aggregate principal amount						5,000,000		7,500,000
Interest rate (as a percent)						8.00%		8.00%
Warrant coverage (as a percent)						20.00%		20.00%
Proceeds received from debt issuance					3,333,000	1,667,000	2,500,000	5,000,000
Minimum gross proceeds from issuance and sale of preferred stock shares to no current holders triggering conversion of debt								20,000
Percentage of price per share paid by other investors in consummation of a qualifying equity fundraising								80.00%
Beneficial conversion feature								2,440,000
Carrying value												12,500,000
Outstanding principal amount converted				12,500,000
Outstanding interest amount converted				684,000
Payment multiple of outstanding principal balance in event of acquisition or asset transfer								3
Convertible Debt Issued 2013 | Series A Convertible Preferred Stock
Convertible debt
Price per share ( in dollars per share)								$1
Minimum percentage of nominal amount of aggregate outstanding principal amount to be converted								60.00%
Percentage of price per share paid by other investors in consummation of a qualifying equity fundraising								80.00%
Number of shares issued upon conversion of debt				13,184,383
Convertible Debt Issued 2013 | Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01
Convertible debt
Number of shares issuable upon exercise of warrants								2,499,996
Exercise price of warrants (in dollars per share)								$0.01
Fair value of warrants								2,472,000
Convertible Debt Issued 2014
Convertible debt
Interest rate (as a percent)				8.00%
Warrant coverage (as a percent)				20.00%
Proceeds received from debt issuance				5,000,000
Minimum gross proceeds from issuance and sale of preferred stock shares to no current holders triggering conversion of debt				20,000,000
Beneficial conversion feature				2,071,000
Outstanding principal amount converted		5,000,000	5,000,000
Outstanding interest amount converted		13,000	13,000
Minimum number of holders not currently holding capital stock that would need to be issued or sold preferred stock to trigger conversion of debt				1
Conversion price in event of corporate merger (in dollars per share)				$1
Payment multiple of outstanding principal balance in event of acquisition or asset transfer				3
Conversion price in event of non-qualified financing (in dollars per share)				$1
Fair value of embedded compound derivative				23,000									23,000
Reduction of additional paid-in capital for extinguishment of convertible debt with beneficial conversion feature	1,150,000
Gain on extinguishment	23,000								22,000
Convertible Debt Issued 2014 | Series B Convertible Preferred Stock
Convertible debt
Exercise price of warrants (in dollars per share)													0.01
Fair value of Series B Preferred issued upon conversion	5,013,000
Convertible Debt Issued 2014 | Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01
Convertible debt
Number of shares issuable upon exercise of warrants				1,000,000
Exercise price of warrants (in dollars per share)				$0.01
Fair value of warrants				1,171,000
Numerator used to determine number of securities called by warrants or rights in qualified financing				1,000
Hercules Notes
Convertible debt
Aggregate principal amount									15,000,000	15,000,000
Price per share ( in dollars per share)									$8.06	$8.06
Number of shares issuable upon exercise of warrants									64,194	64,194
Exercise price of warrants (in dollars per share)									$7.01	$7.01
Fair value of warrants									248,000	248,000
Number of term loans										2
Percentage of prepayment fees										2.00%
Amount of prepayment fees, in case loan is repaid after 18 months										0
Percentage of fees payable on the aggregate principal amount	3.00%									3.00%
Maximum amount of regularly scheduled installment										2,000
Number of consecutive trading days										7 days
Maximum percentage of company's trading volume										15.00%
Number of consecutive trading days for calculating the company's total volume										22
Additional interest applied	4.00%
Right to participate in sales and issuance of equity	1,000,000
Debt issuance costs	49,000
Aggregate costs	463,000
Hercules Notes | Minimum
Convertible debt
Interest rate (as a percent)	7.95%
Base rate	Prime Rate
Subordinated debt amount, in case of default	250,000
Hercules Notes | Prime Rate [Member] | Minimum
Convertible debt
Interest rate (as a percent)	7.95%
Applicable margin ( as a percent)	3.25%
Hercules Term Loan One
Convertible debt
Aggregate principal amount											7,500,000
Number of monthly repayment installments											18 months
Debt discount	231,000
Hercules Term Loan Two
Convertible debt
Aggregate principal amount											$7,500,000

Debt_Details_2

Debt (Details 2) (USD $)	0 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2014
Future principal payments
2016		1,851
2017		2,971
2018		2,678
Total		7,500
Hercules Notes
Convertible debt
Term charge	3.00%	3.00%

Warrants_Details

Warrants (Details) (USD $)	12 Months Ended		0 Months Ended	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014	Mar. 31, 2014	Apr. 30, 2014	Apr. 15, 2014	Oct. 01, 2013	Mar. 13, 2013	Oct. 31, 2013	Jul. 08, 2013	Mar. 10, 2014
Warrants to Purchase Series A Preferred and Common Stock
Fair value of warrants		$5,843
Common stock | Exercise Price 0.08
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	1,379
Exercise price of warrants (in dollars per share)	$0.08
Common stock | Exercise price 7.01
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	64,194
Exercise price of warrants (in dollars per share)	$7.01
Common stock | Exercise Price 7.55
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	20,616
Exercise price of warrants (in dollars per share)	$7.55
Common stock | Exercise Price 68.40
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	3,737
Exercise price of warrants (in dollars per share)	$68.40
Common stock | Exercise Price 68.40 | Zalicus
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	3,737
Exercise price of warrants (in dollars per share)	$68.40
Common stock | Exercise Price 83.40
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	1,079
Exercise price of warrants (in dollars per share)	$83.40
Common stock | Exercise Price 83.40 | Zalicus
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	1,079
Exercise price of warrants (in dollars per share)	$83.40
Common stock | Exercise Price 135.00
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	1,887
Exercise price of warrants (in dollars per share)	$135
Common stock | Exercise Price 135.00 | Zalicus
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	1,887
Exercise price of warrants (in dollars per share)	$135
Common stock | Exercise Price 405.00
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	148
Exercise price of warrants (in dollars per share)	$405
Common stock | Exercise Price 405.00 | Zalicus
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into	148
Exercise price of warrants (in dollars per share)	$405
Series A Convertible Preferred Stock
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into		2,499,996			5,101,816
Exercise price of warrants (in dollars per share)		$0.01
Number of shares issued upon exercise of warrants	5,101,816	498,306
Series B Convertible Preferred Stock
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into					787,402
Number of shares issued upon exercise of warrants	787,402
Series A Preferred Stock Warrants [Member]
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into					5,101,816
Series A Preferred Stock Warrants Exercise Price Dollars 1.00
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into		462,399
Exercise price of warrants (in dollars per share)		$1
Fair value of warrants		311		1,171
Series A Preferred Stock Warrants Exercise Price Dollars 0.01
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into		4,805,327
Exercise price of warrants (in dollars per share)		$0.01
Fair value of warrants		5,532
Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01 | Series B Convertible Preferred Stock
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into				787,402		787,402
Exercise price of warrants (in dollars per share)						$0.01
Warrant
Assumptions to estimate the fair value of warrants
Fair value of warrants			248
Expected volatility			61.68%
Expected term			5 years
Risk-free interest rate			1.78%
Convertible Debt Issued 2013
Warrants to Purchase Series A Preferred and Common Stock
Aggregate principal amount							5,000	7,500
Convertible Debt Issued 2013 | Series A Preferred Stock Warrants Exercise Price Dollars 0.01
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into							333,333	999,999	666,666	499,998
Fair value of warrants							384	826	768	494
Convertible Debt Issued 2013 | Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into								2,499,996
Exercise price of warrants (in dollars per share)								$0.01
Fair value of warrants								2,472
Convertible Debt Issued 2014 | Series B Convertible Preferred Stock
Warrants to Purchase Series A Preferred and Common Stock
Exercise price of warrants (in dollars per share)				$0.01
Convertible Debt Issued 2014 | Series A Preferred Stock Warrants Exercise Price Dollars 1.00
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into				1,000,000
Exercise price of warrants (in dollars per share)				$0.01
Warrants, term				7 years
Convertible Debt Issued 2014 | Series A Preferred Stock Or Qualified Financing Securities Warrants Exercise Price Dollars 0.01
Warrants to Purchase Series A Preferred and Common Stock
Number of securities that warrants may be converted into											1,000,000
Exercise price of warrants (in dollars per share)											$0.01
Fair value of warrants											1,171
Hercules Notes
Warrants to Purchase Series A Preferred and Common Stock
Aggregate principal amount			15,000
Number of securities that warrants may be converted into			64,194
Exercise price of warrants (in dollars per share)			$7.01
Fair value of warrants			$248
Warrants, term			5 years

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (Recurring, Estimate of Fair Value Measurement, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Cash and cash equivalents	$21,462	$1,798
Total assets	21,462	1,798
Liabilities
Warrant liability		5,843
Total liabilities		5,843
Level 1
Assets
Cash and cash equivalents	21,462	1,798
Total assets	21,462	1,798
Level 3
Liabilities
Warrant liability		5,843
Total liabilities		$5,843

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	12 Months Ended	0 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Jul. 15, 2014	Jun. 30, 2014	Apr. 15, 2014	Mar. 31, 2014	Mar. 10, 2014	Dec. 31, 2013
Warrant
Fair Value Assumptions using Black-Scholes
Fair value of warrants		$167
Underlying stock value		$11.80
Warrant | Level 3
Changes in fair value of liabilities in level 3 inputs
Beginning balance	5,843
Warrant issuance	1,171
Change in fair value	222
Warrant exercises	-7,069
Reclassification to equity	-167
Warrant | Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Term of liquidity		3 years 6 months 11 days
Annual volatility (as a percent)		61.58%
Fair Value Assumptions using Black-Scholes
Exercise price		$0.08
Expected volatility		61.58%
Risk-free interest rate		1.34%
Warrant | Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Term of liquidity		5 years 1 month 6 days
Annual volatility (as a percent)		64.96%
Fair Value Assumptions using Black-Scholes
Exercise price		$7.55
Expected volatility		64.96%
Risk-free interest rate		1.70%
Warrant | Hybrid approach | Level 3
Quantitative information for Level 3 Fair Value Measurements Liabilities
Number of possible outcomes considered under valuation model			2	2	2		2
Warrant | Hybrid approach | Minimum | Level 3
Quantitative information for Level 3 Fair Value Measurements Liabilities
Discount rate (as a percent)				21.00%	25.00%	25.00%
Changes in fair value of liabilities in level 3 inputs
Probability weighted value for common stock (as a percent)			20.00%	30.00%	45.00%	45.00%
Discount for lack of marketability (as a percent)			5.00%	11.00%	10.00%	10.00%
Warrant | Hybrid approach | Maximum | Level 3
Quantitative information for Level 3 Fair Value Measurements Liabilities
Discount rate (as a percent)				30.00%	30.00%	30.00%
Changes in fair value of liabilities in level 3 inputs
Probability weighted value for common stock (as a percent)			80.00%	70.00%	55.00%	55.00%
Discount for lack of marketability (as a percent)			30.00%	34.00%	28.00%	28.00%
Warrant | DCF method | Level 3
Quantitative information for Level 3 Fair Value Measurements Liabilities
Discount rate (as a percent)				22.00%	30.00%		35.00%
Warrant | OPM | Level 3
Quantitative information for Level 3 Fair Value Measurements Liabilities
Term of liquidity			2 years 3 months	2 years 5 months 16 days	2 years 6 months 11 days		2 years 9 months
Annual volatility (as a percent)				59.00%	58.00%		53.00%
Fair Value Assumptions using Black-Scholes
Expected volatility				59.00%	58.00%		53.00%
Embedded Derivative Financial Instruments [Member] | Level 3
Changes in fair value of liabilities in level 3 inputs
Warrant issuance	23
Derecognition of embedded compound derivative	-23
Embedded Derivative Financial Instruments [Member] | Convertible Debt Issued 2014
Changes in fair value of liabilities in level 3 inputs
Notes issued						5,000
Embedded Derivative Financial Instruments [Member] | With and Without Approach Technique | Level 3
Changes in fair value of liabilities in level 3 inputs
Market yield (as a percent)				25.00%	25.00%	25.00%
Embedded Derivative Financial Instruments [Member] | With and Without Approach Technique | Minimum | Level 3
Changes in fair value of liabilities in level 3 inputs
Probability of occurrence of certain events (as a percent)				0.00%	5.00%	5.00%
Recovery rate (as a percent)				31.00%	31.00%	31.00%
Embedded Derivative Financial Instruments [Member] | With and Without Approach Technique | Maximum | Level 3
Changes in fair value of liabilities in level 3 inputs
Probability of occurrence of certain events (as a percent)				100.00%	50.00%	50.00%
Recovery rate (as a percent)				47.00%	47.00%	47.00%

Capital_Stock_Details

Capital Stock (Details) (USD $)	0 Months Ended		1 Months Ended	12 Months Ended
	Jul. 15, 2014	Apr. 15, 2014	Apr. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Jul. 16, 2014
				director
				item
Capital Stock
Common stock - shares authorized				300,000,000	300,000,000
Common stock (par value)				$0.00	$0.00
Common stock - shares issued				934,102	237,026
Common Stock, Shares, Outstanding				920,843	237,026
Preferred Stock, Shares Authorized				5,000,000	5,000,000
Preferred stock (par value)				$0.00	$0.00
Preferred Stock, Shares Issued				0	0
Preferred Stock, Shares Outstanding				0	0
Authorized capital	305,000,000
Shares reserved for future issuances				4,744,400	33,256,942
Convertible Debt Issued 2014
Capital Stock
Outstanding principal amount converted		$5,000,000	$5,000,000
Outstanding interest amount converted		13,000	13,000
Settlement of long-term debt
Capital Stock
Shares reserved for future issuances				248,093
Convertible Preferred Stock [Member]
Capital Stock
Shares reserved for future issuances					27,248,746
Employee Stock Option [Member]
Capital Stock
Shares reserved for future issuances				4,403,266	740,470
Preferred Stock | Warrant
Capital Stock
Shares reserved for future issuances					5,267,726
Common stock | Warrant
Capital Stock
Shares reserved for future issuances				93,040
Series A Convertible Preferred Stock
Capital Stock
Issuance of shares				13,184,383
Number of classes holders entitled to vote as for all matters except approval of certain major actions and election of directors				1
Number of directors that holders are entitled to vote for as a separate class				3
Dividend rate (as a percent)				8.00%
Dividends declared				0
Multiple of original issuance price used for determination of liquidation rights				3
Adjustment to carrying amount of temporary equity for liquidation event				0
Series B Convertible Preferred Stock
Capital Stock
Issuance of shares			24,409,444	24,409,444
Proceeds from issuance of shares			31,000,000
Number of shares issued upon conversion of debt		3,947,363	3,947,363
Number of classes holders entitled to vote as for all matters except approval of certain major actions and election of directors				1
Number of directors that holders are entitled to vote for as a separate class				1
Number of directors that holders are entitled to vote for as a separate class if common stock of company or affiliate not listed on public trading platform by October 15, 2014				2
Dividend rate (as a percent)				8.00%
Dividends declared				0
Multiple of original issuance price used for determination of liquidation rights				3
Adjustment to carrying amount of temporary equity for liquidation event				$0
Common Class A
Capital Stock
Common stock (par value)						$0.00
Number of directors that holders are entitled to vote for as a separate class				1

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (USD $)	1 Months Ended	12 Months Ended		0 Months Ended	3 Months Ended	1 Months Ended	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 15, 2014	Sep. 30, 2014	Aug. 31, 2014	Dec. 21, 2009	Apr. 01, 2014	Mar. 31, 2014
Stock-Based Compensation
Stock-based compensation expense		$1,719	$140
Vesting percentage	25.00%
Weighted average fair value
Cash received from exercise of stock options		90	21
Zalicus
Stock-Based Compensation
Stock-based compensation expense					355
Acquisition-date fair value of assumed Zalicus equity awards attributable to precombination services				220
Weighted-average assumptions
Risk-free interest rate				1.91%
Expected volatility				66.02%
Minimum | Zalicus
Weighted-average assumptions
Expected term				1 month 6 days
Maximum | Zalicus
Weighted-average assumptions
Expected term				6 years
Employees Of Acquirees [Member] | Zalicus
Stock-Based Compensation
Stock-based compensation expense		355
Non Employees Of Acquirees [Member] | Zalicus
Stock-Based Compensation
Stock-based compensation expense		303
Employee And Directors Stock Options [Member]
Stock-Based Compensation
Vesting Period		4 years
Vesting percentage		25.00%
Number of Options
Outstanding at the beginning of the period		458,871
Granted		1,241,576
Exercised		-98,405
Cancelled		-83,614
Outstanding at the end of the period		1,652,882	458,871
Vested and expected to vest at end of period		1,596,713
Exercisable at end of period		248,134
Weighted-Average Exercise Price
Outstanding at the beginning of the period		$0.96
Granted		$7.73
Exercised		$0.91
Cancelled		$36.99
Outstanding at the end of the period		$10.03	$0.96
Vested and expected to vest at end of period		$10.15
Exercisable at end of period		$28.14
Weighted-Average Remaining Contractual Term
Outstanding at end of period		8 years 10 months 24 days
Vested and expected to vest at end of period		8 years 10 months 24 days
Exercisable at end of period		7 years 4 months 24 days
Aggregate Intrinsic Value
Outstanding at end of period		1,628
Vested and expected to vest at end of period		1,590
Exercisable at end of period		672
Total intrinsic value of options exercised		71	21
Total fair value of employee stock options vested		353	208
Weighted average fair value
Weighted average grant-date fair value of options granted during the period		$4.62	$0.16
Cash received from exercise of stock options		90	21
Unrecognized stock-based compensation expense
Unrecognized stock-based compensation expense		$4,909
Unrecognized stock-based compensation expense, Recognition period		3 years 3 months 11 days
Weighted-average assumptions
Expected volatility			66.99%
Expected term		6 years	6 years
Expected dividend yield		0.00%	0.00%
Employee And Directors Stock Options [Member] | Zalicus
Number of Options
Options assumed through Zalicus merger		134,454
Weighted-Average Exercise Price
Options assumed through Zalicus merger		$72.02
Employee And Directors Stock Options [Member] | Minimum
Weighted-average assumptions
Risk-free interest rate		1.80%	1.09%
Expected volatility		63.96%
Employee And Directors Stock Options [Member] | Maximum
Stock-Based Compensation
Vesting Period		10 years
Weighted-average assumptions
Risk-free interest rate		2.09%	1.81%
Expected volatility		66.07%
2014 Plan
Stock-Based Compensation
Increase in number of shares available for issuance						3,000,000
Shares available for issuance		2,750,384
2004 Plan
Stock-Based Compensation
Authorized number of shares							333,333
2004 Plan | Minimum
Stock-Based Compensation
Shares available for issuance							66,667
Vesting percentage							4.00%
2011 Plan
Stock-Based Compensation
Authorized number of shares								1,504,752	740,470

StockBased_Compensation_Detail1

Stock-Based Compensation (Details 2) (USD $)	1 Months Ended	12 Months Ended	1 Months Ended				0 Months Ended	1 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	31-May-13	Dec. 31, 2012	Jun. 30, 2012	31-May-12	Apr. 15, 2014	Sep. 30, 2014	Apr. 30, 2014
					item	item
Stock-Based Compensation
Vesting percentage	25.00%
Vendor For Consulting Services [Member]
Stock-Based Compensation
Upfront fee		$200,000
Monthly consulting fee		25,000
Period of consulting		18 months
Executive Employment Agreements Member
Stock-Based Compensation
Number of executives					2	2
Stock options granted			44,349	48,924
Executive Employment Agreements Member | Equity Financing Member
Stock-Based Compensation
Minimum receipts from new investors in first anniversary						25,000
Minimum Increase in Price Per Share of Series A Preferred price per share						10.00%
Series A Preferred price per share						1
Executive Employment Agreements Member | Strategic Partnership Milestone Member
Stock-Based Compensation
Minimum initial payments and non-contingent milestone payments within 12 months of the effectiveness of the transaction						25,000
Minimum aggregate payments received, excluding amounts received						50,000
Additional equity interest percentage for granting stock options						1.00%
Restricted Stock
Stock-Based Compensation
Shares granted		58,560
Shares vested during the period		45,301
Restricted Stock | Vendor For Consulting Services [Member]
Stock-Based Compensation
Shares granted	53,036							53,036	53,036
Vesting percentage		75.00%					25.00%
Shares vested during the period									13,259
Restricted Stock | Vendor For Consulting Services [Member] | General and Administrative Expense [Member]
Stock-Based Compensation
Expense recorded		98,000
Restricted Stock | Executive Employment Agreements Member
Stock-Based Compensation
Vesting percentage								50.00%
Restricted Stock | Executive Employment Agreements Member | General and Administrative Expense [Member]
Stock-Based Compensation
Expense recorded								185,000
Restricted Stock | Former Non Employee [Member] | General and Administrative Expense [Member]
Stock-Based Compensation
Expense recorded		$303,000

StockBased_Compensation_Detail2

Stock-Based Compensation (Details 3) (USD $)	12 Months Ended		6 Months Ended		0 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2014	Jul. 15, 2014	Jul. 14, 2014
Stock-Based Compensation
Stock-based compensation expense	$1,719	$140
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Granted	58,560
Vested	-45,301
Non-vested at ending period	13,259		13,259	13,259
Weighted Average Grant Date Fair Value
Granted	$5.08
Vested	$5.08
Non-vested at ending period	$5.08		$5.08	$5.08
Restricted Stock Units (RSUs) [Member]
Stock-Based Compensation
Stock-based compensation expense			277	355
Decrease in additional paid in capital	$297
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Granted	27,777
Vested	-27,777
Weighted Average Grant Date Fair Value
Granted	$11.80
Vested	$11.80
Restricted Stock Units (RSUs) [Member] | Zalicus
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Granted					25,000
Cancelled						52,777

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income tax benefit (expense)	$43
Alternative minimum tax		20
Deferred tax assets deferred gain on intercompany sale of intangible assets		943
Components of U.S. and foreign loss from continuing operations before income taxes
United States	-16,149	-16,601
Foreign	-25,738	-4,194
Loss before income taxes	-41,887	-20,795
BRAZIL
Offset by withholding income tax		61
SWITZERLAND
Offset by withholding income tax		100
Amortization period		5 years
In Process Research and Development
Income tax benefit (expense)	$184

Income_Taxes_Details_2

Income Taxes (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets
Accrued rent	$208
Accrued expenses & other	539	310
Gross current deferred tax assets	747	310
Non-current assets:
Net operating loss - U.S.	11,660	7,403
Research and development credits	573	193
License/Start Up expenditures	222	242
Accrued Rent	111
AMT credit		20
Other	147	3
Capitalized R&D	5,611
Foreign investment tax credit	4,370
Net operating loss - foreign	35,546	1,225
Gross non-current deferred tax assets	58,240	9,086
Gross Deferred tax assets	58,987	9,396
Non-current deferred tax liabilities:
Depreciation	-14
Swiss IP amortization	-85
Identifiable intangible assets - IPR&D	-2,166
Total non-current deferred tax liabilities	-2,265
Net non-current deferred tax liability	-553	-738
Gross deferred taxes	56,722	9,396
Valuation allowance	-58,888	-9,396
Net deferred tax (liability)	-2,166
Deferred tax liability	$2,166

Income_Taxes_Details_3

Income Taxes (Details 3) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount
Income tax benefit using U.S. federal statutory rate	($14,241)	($7,076)
State income taxes, net of federal benefit	-296	-784
Other permanent differences	2,985	1,581
Foreign rate differential	3,836	574
Tax credits	-223	143
Other items	503	21
Tax benefit related to the IPR&D transfer	185
Foreign withholding taxes	101
Net change in valuation allowance	7,477	5,827
Income Tax Expense (Benefit), Total	($43)

Income_Taxes_Details_4

Income Taxes (Details 4) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Excess tax benefits credited to additional paid-in capital	$77	$0
Foreign investment tax credit	5,283
Uncertain tax position	0
Interest expense related to uncertain tax positions	0	0
Term of other credits excluding research and development tax credit	15 years
SWITZERLAND
Operating Loss Carryforwards [Line Items]
Term of net operating loss carryforward	7 years
CANADA
Operating Loss Carryforwards [Line Items]
Term of net operating loss carryforward	20 years
Domestic Country [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	32,104	20,178
Research and development tax credit carryforwards	454	152
State And Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Research and development tax credit carryforwards	180	61
Foreign Country [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$144,935	$6,028

Committments_Details

Committments (Details) (USD $)	0 Months Ended		12 Months Ended		1 Months Ended				3 Months Ended	1 Months Ended
	Dec. 31, 2014	15-May-14	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Oct. 31, 2013	Jun. 30, 2013	Apr. 30, 2013	Mar. 31, 2014	Jan. 31, 2009	Sep. 30, 2014	Mar. 31, 2013
Term of lease		7 years
Rent expense			$38,000
Incentive received from leasehold improvement	477,000
Commitments to lease		3,248,000
Future minimum lease payments under the First Amendment
2015	1,812,000		1,812,000
2016	1,719,000		1,719,000
2017	567,000		567,000
2018	472,000		472,000
2019	480,000		480,000
2019 and thereafter	817,000		817,000
Total	5,867,000		5,867,000
Less: Future sublease payments to be received	-1,854,000		-1,854,000
Net future lease payments	4,013,000		4,013,000
Operating lease rent expense			366,000	236,000
Epirus Switzerland Member
Monthly lease rate					6,000						3,000
Notice period					12 months
Future minimum lease payments under the First Amendment
Net future lease payments					84,000
Other Current Liabilities
Liability recognized as future minimum lease payments	1,853,000		1,853,000
Other Noncurrent Liabilities
Liability recognized as future minimum lease payments	2,562,000		2,562,000
BOW015
Future minimum lease payments under the First Amendment
Upfront payment			250,000
License Agreements | Catalent Pharma Solutions, LLC
Future minimum lease payments under the First Amendment
Aggregate payments upon the achievement of certain development and regulatory milestones			700,000
Additional obligation amount to be paid upon achievement of certain development and regulatory milestones	500,000		500,000
Period of commercial sale of product			20 years
Maximum percentage paid			1
Period of notice for termination of agreement			60 days
License Agreements | Bioceros B.V.
Future minimum lease payments under the First Amendment
Upfront payment						70,000		300,000	300,000
Payments made upon exercise of its option							400,000
Aggregate payments upon the achievement of certain development and regulatory milestones			1,200,000
Period of commercial sale of product			10 years
Maximum percentage paid			1
Period of notice for termination of agreement for material breach of agreement			30 days
Period of notice for termination of agreement			60 days
amounts paid	200,000		200,000
Moksha8 Pharmaceuticals Inc | License Agreements
Future minimum lease payments under the First Amendment
Upfront payment										100,000
Payments made upon exercise of its option										100,000
Moksha8 Pharmaceuticals Inc | License Agreements | Catalent Pharma Solutions, LLC | BOW015
Future minimum lease payments under the First Amendment
Milestone payments on clinical trial												$200,000

Net_loss_per_share_Details

Net loss per share (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding		27,248,746
Settlement of long-term debt
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	248,093	13,002,222
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	1,652,882	458,871
Warrant | Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding		5,267,726
Warrant | Common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	93,040
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	13,259

Employee_Benefits_Details

Employee Benefits (Details)	12 Months Ended
	Dec. 31, 2014
Employee Benefits.
Minimum age of the employees to participate in defined contribution plan	21 years

Related_Parties_Details

Related Parties (Details)	Dec. 31, 2014	Feb. 28, 2015
Livzon Mabpharm Inc
Related Parties
Percentage of ownership owned	12.00%
Moksha8 Pharmaceuticals Inc
Related Parties
Percentage of ownership owned	17.00%
Subsequent event
Related Parties
Percentage of ownership owned		-7.00%

Legal_Proceedings_Details

Legal Proceedings (Details) (USD $)	0 Months Ended	12 Months Ended	0 Months Ended		1 Months Ended
	2-May-14	Dec. 31, 2014	Apr. 16, 2014	Jan. 13, 2015	Mar. 31, 2015
	lawsuit	lawsuit	lawsuit
Zalicus Shareholder Litigation Filed In Massachusetts [Member]
Legal Proceedings
Number of putative class action lawsuits filed	3
Number of putative class action lawsuits voluntarily dismissed by plaintiffs		1
Number of putative class action lawsuits consolidated into single action by plaintiffs		2
Global fees and expense payments to counsel		$400,000
Insurance policy for covering the plaintiffs' counsel's fees and expenses		400,000
Zalicus Shareholder Litigation Filed In Delaware [Member]
Legal Proceedings
Number of putative class action lawsuits filed			3
Zalicus Shareholder Litigations Filed In Delaware And Massachusetts [Member]
Legal Proceedings
Agreed to pay a combined global fee amount				$350
Subsequent event
Legal Proceedings
Arbitration period					6 months
Period of notice for termination of agreement for material breach of agreement					30 days

Subsequent_Events_Details

Subsequent Events (Details) (Subsequent event, USD $)	0 Months Ended
	Feb. 13, 2015	Feb. 04, 2015	Jan. 23, 2015
Common stock shares issued through underwritten public offering	$958,208	$9,600,000
Share price (in dollars per share)	$5	$5
Proceeds from issuance	4,400	43,555
Net proceeds from its equity offering		$47,955,000
LPC
Number of business day following delivery of the notice of termination			1 day