Eiger BioPharmaceuticals (EIGRQ) 10-Q 8 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Nov. 03, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	EIGR
Entity Registrant Name	Eiger BioPharmaceuticals, Inc.
Entity Central Index Key	1,305,253
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		8,356,659

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 56,294	$ 4,778
Prepaid expenses and other current assets	912	717
Total current assets	57,206	5,495
Property and equipment, net	79	41
Other assets	142	46
Total assets	57,427	5,582
Current liabilities:
Accounts payable	4,075	1,940
Accrued liabilities	1,272	1,006
Convertible promissory note		5,444
Total current liabilities	5,347	8,390
Warrant liability		885
Obligation to issue common stock		1,457
Other long term liabilities	15	2
Total liabilities	5,362	10,734
Stockholders’ equity (deficit):
Convertible preferred stock		22,567
Common stock	8
Additional paid-in capital	115,647	1,552
Accumulated deficit	(63,590)	(29,271)
Total stockholders’ equity (deficit)	52,065	(5,152)
Total liabilities and stockholders’ equity (deficit)	$ 57,427	$ 5,582

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating expenses:
Research and development	$ 8,072	$ 2,110	$ 23,637	$ 4,493
General and administrative	3,264	762	9,574	1,768
Total operating expenses	11,336	2,872	33,211	6,261
Loss from operations	(11,336)	(2,872)	(33,211)	(6,261)
Other expense, net:
Interest expense			(685)
Other expense, net	(34)		(423)
Net loss and comprehensive loss	$ (11,370)	$ (2,872)	$ (34,319)	$ (6,261)
Net loss per common share, basic and diluted	$ (1.49)	$ (14.70)	$ (6.58)	$ (32.22)
Weighted-average common shares outstanding, basic and diluted	7,622,963	195,323	5,218,099	194,346

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Eiccose LLC [Member]	Common Stock [Member]	Common Stock [Member]Eiccose LLC [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]Eiccose LLC [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2015	$ (5,152)					$ 1,552		$ (29,271)
Temporary equity, Beginning balance at Dec. 31, 2015		$ 22,567
Beginning Balance, Shares at Dec. 31, 2015				273,993
Temporary equity, Beginning balance, Shares at Dec. 31, 2015		2,609,102
Issuance of common stock upon private placement, net of $1.3 million of issuance cost	32,108			$ 2		32,106
Issuance of common stock upon private placement, net of $1.3 million of issuance cost, Shares				1,954,390
Conversion of preferred stock into common stock, Temporary equity value	6,129	$ (22,567)				6,129
Issuance of common stock upon conversion of convertible promissory note, Shares				350,040
Conversion of preferred stock into common stock, Temporary equity shares		(2,609,102)
Issuance of common stock upon exercise of warrants	1,057					1,057
Issuance of common stock upon exercise of warrants, Shares				61,254
Issuance of common stock to Eiccose upon private placement			$ 1,661				$ 1,661
Issuance of common stock to Eiccose upon private placement, Shares					96,300
Conversion of preferred stock into common stock				$ 3		22,564
Conversion of preferred stock into common stock, Shares				2,609,102
Issuance of common stock upon reverse merger	27,390			$ 2		27,388
Issuance of common stock upon reverse merger, Shares				1,596,959
Issuance of common stock upon execution of license agreement	3,172					3,172
Issuance of common stock upon execution of license agreement, Shares				157,587
Issuance of common stock upon public offering, net of $1.8 million of issuance costs	18,229			$ 1		18,228
Issuance of common stock upon public offering, net of $1.8 million of issuance costs, Shares				1,250,000
Issuance of common stock upon exercise of options	$ 39					39
Issuance of common stock upon exercise of options, Shares	7,034			7,034
Stock-based compensation expense	$ 1,751					1,751
Net loss	(34,319)							(34,319)
Ending Balance at Sep. 30, 2016	$ 52,065			$ 8		$ 115,647		$ (63,590)
Ending Balance, Shares at Sep. 30, 2016				8,356,659

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Private Placement [Member]
Issuance of common stock, issuance stock	$ 1.3
Initial Public Offering [Member]
Issuance of common stock, issuance stock	$ 1.8

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net loss	$ (34,319)	$ (6,261)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	15	8
Non-cash interest expense	685
Stock-based compensation	1,751	72
Issuance of common stock in connection with a license agreement	3,172	213
Change in fair value of obligation to issue shares to Eiccose	204
Change in fair value of warrant liability	165
Change in assets and liabilities:
Prepaid expenses and other current assets	(5)	(301)
Other non-current assets	(88)	(21)
Accounts payable	2,135	375
Accrued and other liabilities	(547)	100
Net cash used in operating activities	(26,832)	(5,815)
Investing activities
Cash received from merger transaction	28,018
Purchase of property and equipment	(53)	(27)
Net cash provided by (used in) investing activities	27,965	(27)
Financing activities
Proceeds from issuance of common stock upon private placement, net of issuance cost	32,108
Proceeds from issuance of common stock upon public offering, net of issuance cost	18,229
Proceeds from issuance of common stock upon options exercises	39
Proceeds from issuance of common stock upon warrants exercises	7
Proceeds from issuance of preferred stock, net of issuance costs		7,201
Net cash provided by financing activities	50,383	7,201
Net increase in cash and cash equivalents	51,516	1,359
Cash and cash equivalents at beginning of period	4,778	777
Cash and cash equivalents at end of period	56,294	2,136
Non-cash activities:
Conversion of warrant liability to common stock upon private placement	1,050
Issuance of common stock in connection with a license agreement	3,172	$ 213
Proceeds from issuance of common stock upon private placement, net of issuance cost	32,108
Non-cash net liabilities assumed in reverse merger	671
Conversion of convertible promissory note to common stock upon private placement	6,129
Conversion of preferred stock to common stock upon reverse merger	22,567
Eiccose LLC [Member]
Financing activities
Proceeds from issuance of common stock upon private placement, net of issuance cost	1,661
Non-cash activities:
Proceeds from issuance of common stock upon private placement, net of issuance cost	$ 1,661

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Description of Business	1. Description of Business Eiger BioPharmaceuticals, Inc. (the “Company”) was incorporated in the State of Delaware on November 6, 2008. The Company is a clinical-stage biopharmaceutical company committed to bringing to market novel products for the treatment of orphan diseases. The Company has built a diverse portfolio of well-characterized product candidates with the potential to address diseases for which the unmet medical need is high, the biology for treatment is clear, and for which an effective therapy is urgently needed. The Company’s principal operations are based in Palo Alto, California and it operates in one segment. Reverse Merger On March 22, 2016, Eiger BioPharmaceuticals, Inc. (“Eiger”) completed its merger with Celladon Corporation (“Celladon”) in accordance with the terms of the Agreement and Plan of Merger and Reorganization, dated November 18, 2015 (the “Merger Agreement”), by and among Celladon, Celladon Merger Sub, Inc. (“Merger Sub”) and Eiger (the “Merger”). Pursuant to the Merger Agreement, Merger Sub merged with and into Eiger, with Eiger becoming a wholly-owned subsidiary of Celladon and the surviving corporation of the Merger. Pursuant to the terms and subject to the conditions set forth in the Merger Agreement, Eiger stockholders became the majority stockholders of the surviving company. In connection with, and immediately prior to, the closing of the Merger, on March 22, 2016, Celladon filed an amendment to its amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to effect a fifteen-for-one reverse stock split of its common stock (the “Reverse Stock Split”). In connection with and immediately following the consummation of the Merger, on March 22, 2016, Celladon filed an amendment to its amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to change its name to Eiger BioPharmaceuticals, Inc. The Company’s shares of common stock listed on the NASDAQ Global Market, previously trading through the close of business on Tuesday, March 22, 2016 under the ticker symbol “CLDN,” commenced trading on the NASDAQ Global Market, on a post-reverse stock split adjusted basis, under the ticker symbol “EIGR” on March 23, 2016. On March 22, 2016, a Certificate of Merger was filed with the Secretary of State of the State of Delaware to effect the Merger of Merger Sub with and into Eiger. See Note 4 for further details. The Company, or Eiger, as used in the accompanying notes to the unaudited condensed consolidated financial statements, refers to Private Eiger prior to the completion of the Merger and Public Eiger subsequent to the completion of the Merger. Reverse Stock Split and Exchange Ratio On March 22, 2016, and prior to the closing of the Merger, Celladon completed a fifteen-for-one reverse stock split. As a result of the reverse stock split, every fifteen shares of Celladon common stock outstanding immediately prior to the Merger were combined and reclassified into one share of Celladon common stock. No fractional shares were issued in connection with the reverse stock split. The holders of shares of Eiger common stock outstanding immediately prior to the Merger received approximately 0.09 shares of Celladon common stock in exchange for each share of Eiger common stock in the Merger. Following the reverse stock split and the Merger on March 22, 2016, the combined company had 6,945,401 shares of common stock outstanding. The accompanying unaudited condensed consolidated financial statements and notes to the unaudited condensed consolidated financial statements give retroactive effect to the Reverse Stock Split for all periods presented. Liquidity The Company had an accumulated deficit of $63.6 million as of September 30, 2016 and negative cash flows from operating activities and expects to continue to incur losses for the next several years. On March 22, 2016, the Company completed the Merger which provided $28.0 million in net cash (see Note 4). In addition, prior to the closing of the Merger, the Company received approximately $33.5 million in cash from the issuance of common stock issued to third parties and existing stockholders (see Note 8). On August 23, 2016, the Company completed an underwritten public offering of 1,250,000 shares of its Common Stock at a price to the public of $16.00 per share, totaling $20.0 million gross proceeds, before deducting underwriting discounts and commissions and estimated offering expenses totaling approximately $1.8 million. Management believes that the currently available resources will be sufficient to fund its operations for approximately the next 12 months. However, if the Company’s anticipated operating results are not achieved in future periods, management believes that planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund the Company’s operations. The Company may consider to raise additional capital through the issuance of additional equity and potentially through borrowings.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of Eiger BioPharmaceuticals, Inc. and its wholly owned subsidiaries, EBPI Merger Inc., EB Pharma LLC and Eiger BioPharmaceuticals Europe Limited, and have been prepared in accordance with accounting principles generally accepted in the United States of America, (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s financial information. These interim results are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for any other interim period or for any other future year. The balance sheet as of December 31, 2015 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. All intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto contained in the Company’s Form 8-K/A and Form 8-K/A Amendment No.2 for the year ended December 31, 2015, filed with the Securities and Exchange Commission on May 13, 2016 and June 17, 2016, respectively. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to clinical trial accrued liabilities, stock-based compensation and income taxes. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates. Accrued Research and Development Costs The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided, but not yet invoiced, and includes these costs in accrued liabilities in the unaudited condensed consolidated balance sheets and within research and development expense in the unaudited condensed consolidated statements of operations and comprehensive loss. These costs are a significant component of the Company’s research and development expenses. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. Research and Development Expenses Research and development costs are expensed as incurred and consist of payroll expenses, stock-based compensation expense, lab supplies and allocated facility costs, as well as fees paid to third parties that conduct certain research and development activities on the Company’s behalf. Amounts incurred in connection with license and asset purchase agreements are also included in research and development expense. Stock-Based Compensation Expense Stock-based awards to employees and directors, including stock options, are recorded at fair value as of the grant date using the Black-Scholes option pricing model and recognized as expense on a straight line-basis over the employee’s or director’s requisite service period (generally the vesting period). Non-cash stock compensation expense is based on awards ultimately expected to vest and is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. The determination of fair value for stock-based awards on the date of grant using an option pricing model requires management to make certain assumptions regarding subjective variables. Stock-based awards and stock options issued to non-employee consultants are recorded at fair value and remeasured at the end of each period as they vest using the Black-Scholes option pricing model. Expense is recognized over the vesting period which is generally the same as the service period. Net Loss per Share Basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net loss per share because including such securities would be anti-dilutive (in common stock equivalent shares): Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Options to purchase common stock 1,124,044 260,184 1,124,044 260,184 Warrants to purchase common stock 10,180 — 10,180 — Convertible preferred stock — 2,609,102 — 2,609,102 Total 1,134,224 2,869,286 1,134,224 2,869,286 Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board, (“FASB”), issued Accounting Standards Update, (“ASU”), ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) On February 25, 2016 the FASB issued ASU 2016-02, Leases (Topic 842), In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually). At September 30, 2016 and December 31, 2015 the carrying amount of cash and cash equivalents, prepaid expenses, accounts payable and accrued liabilities approximated their estimate fair value due to their relatively short maturities. Management believes the terms of the convertible promissory notes reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company’s debt approximated its fair value. Assets and liabilities recorded at fair value on a recurring basis in the unaudited condensed consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 : Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 : Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 : Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. The Company did not have any financial instruments that were measured at fair value on a recurring basis as of September 30, 2016. The Company’s financial instruments as of December 31, 2015 included a warrant liability and an obligation to issue common stock in connection with the Eiccose asset purchase agreement, which were classified as Level 3. See Notes 6 and 7 for further discussion on the obligation to issue common stock and the warrant liability. As of December 31, 2015, in order to determine the fair value of the Company’s warrant liability and the obligation to issue common stock in connection with the Eiccose asset purchase agreement, the Company engaged an independent third-party valuation expert to determine the fair value of these instruments based on the common stock value which is based on probability weighted scenarios, each based on an income approach. The income approach estimates enterprise value based on the expectation of future cash flows that the Company will generate over the forecast horizon and a terminal value at the end of the forecast horizon. These future cash flows and terminal value are discounted to their present values using a discount rate based upon the required rate of return based on the risks associated with the investment. Upon settlement in March 2016, the Company remeasured the fair value of the Company’s warrant liability and the obligation to issue common stock in connection with the Eiccose asset purchase agreement based on the fair value of the common stock that was issued upon settlement of these instruments. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the periods presented. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): December 31, 2015 Level 1 Level 2 Level 3 Total Financial liabilities: Warrant liability $ — $ — $ 885 $ 885 Obligation to issue common stock $ — $ — $ 1,457 $ 1,457 Total $ — $ — $ 2,342 $ 2,342 The following table provides a reconciliation of liabilities measured at fair value using Level 3 significant unobservable inputs (in thousands) for the nine months ended September 30, 2016: Nine Months Ended September 30, 2016 Balance, beginning of period $ 2,342 Change in fair value of common stock warrants and obligation to issue common stock to Eiccose (1) 369 Settlement of warrant liability upon exercise of common stock warrants (1,050 ) Settlement of Eiccose obligation upon issuance of common stock (1,661 ) Balance, end of period $ — (1) Changes in fair value of the obligation to issue common stock are recorded in other expense, net on the accompanying unaudited condensed consolidated statements of operations and comprehensive loss.

Reverse Merger

Reverse Merger	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Reverse Merger	4. Reverse Merger On March 22, 2016, Eiger completed the Merger with Celladon as discussed in Note 1. For accounting purposes, Eiger is considered to be acquiring Celladon in the Merger. Eiger was determined to be the accounting acquirer based upon the terms of the Merger and other factors including; (i) Eiger security holders owned approximately 78% of the combined company immediately following the closing of the Merger, (ii) Eiger directors held all of the board seats in the combined company, and (iii) Eiger management held all key positions in the management of the combined company. The Merger was be accounted for as an asset acquisition rather than business combination because the assets acquired and liabilities assumed by Eiger did not meet the definition of a business as defined by U.S. GAAP. The net assets acquired in connection with this transaction were recorded at their estimated acquisition date fair values as of March 22, 2016, the date the Merger with Celladon was completed. Immediately prior to the effective date of the Merger and in connection with the private placement, the principal outstanding convertible promissory notes (“Promissory Notes” or “Notes”) of Eiger converted into shares of common stock of Eiger. Further, all outstanding warrants issued in connection with the Promissory Notes were exercised for common stock (see Note 7) and all shares of preferred stock of Eiger converted into shares of common stock of Eiger. At the effective date of the Merger, Celladon issued shares of its common stock to Eiger stockholders, at an exchange rate of approximately 0.09 shares of common stock, after taking into account the Reverse Stock Split, in exchange for each share of Eiger common stock outstanding immediately prior to the Merger. The exchange rate was calculated by a formula that was determined through arms-length negotiations between Celladon and Eiger. The combined Company assumed all of the outstanding options, whether or not vested, under the Eiger 2009 Equity Incentive Plan (the “Eiger Plan”) with such options henceforth representing the right to purchase a number of shares of Celladon common stock equal to 0.09 multiplied by the number of shares of Eiger common stock previously represented by such options. Immediately after the Reverse Stock Split and the Merger on March 22, 2016, there were 6,945,401 shares of the combined Company’s common stock outstanding. In addition, immediately after the Merger, pre-Merger Eiger stockholders, warrantholders and optionholders owned approximately 78% of the aggregate number of shares of the combined Company’s common stock, and the stockholders of Celladon immediately prior to the Merger owned approximately 22% of the aggregate number of shares of the combined Company’s common stock (on a fully diluted basis). On March 22, 2016, Celladon had 1.6 million shares of common stock outstanding and a market capitalization of $27.5 million. The estimated fair value of the net assets of Celladon on March 22, 2016 was $27.3 million. The fair value of Celladon’s common stock on the Merger closing date was above the fair value of Celladon’s net assets. As Celladon’s net assets were predominantly comprised of cash offset by current liabilities, the fair value of Celladon’s net assets as of March 22, 2016 was considered to be the best indicator of the fair value and, therefore, the estimated purchase consideration. The following table summarizes the net assets acquired based on their estimated fair values as of March 22, 2016 (in thousands): Cash $ 28,018 Prepaid and other assets 198 Current liabilities (857 ) Non-current liabilities (12 ) Net acquired tangible assets 27,347 Estimated total purchase consideration $ 27,347

License Agreements

License Agreements	9 Months Ended
	Sep. 30, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	5. License Agreements Bristol-Meyers Squibb License Agreement On April 20, 2016, the Company and Bristol-Myers Squibb Company (“BMS”) entered into a License Agreement (the “BMS License Agreement”) and a Common Stock Purchase Agreement (the “BMS Purchase Agreement”). Under the BMS License Agreement, BMS granted the Company an exclusive, worldwide, license to research, develop, manufacture, and sell products containing the proprietary BMS molecule known as PEG-interferon Lambda-1a (the “Licensed Product”) for all therapeutic and diagnostic uses in humans and animals. The Company is responsible for the development and commercialization of the Licensed Product at its sole cost and expense. The License Agreement requires the Company to make an upfront payment of $2.0 million in cash and issue $3.0 million in Company common stock and includes development and regulatory milestone payments totaling $61.0 million and commercial sales milestones of up to $128.0 million. The Company is obligated to pay BMS annual net sales royalties in the range of mid-single to mid-teens, depending on net sales levels. In addition, if the Company grants a sublicense, the Company is obligated to pay BMS a portion of the sublicensing income received. The Company paid BMS an upfront payment of $2.0 million in April 2016, which was charged to research and development expense in the unaudited condensed consolidated statement of operations and comprehensive loss as there is no future alternative use for the intellectual property licensed. The BMS Purchase Agreement provides for the issuance of 157,587 shares of common stock of the Company to BMS in consideration of the license granted to the Company under the BMS License Agreement. The BMS Purchase Agreement grants BMS certain registration rights with respect to the shares of common stock delivered, and BMS has agreed to certain trading and other restrictions with respect to the shares purchased. In April 2016, the Company issued 157,587 common shares to BMS for an aggregate fair value of $3.2 million, which was charged to research and development expense in the unaudited condensed consolidated statement of operations and comprehensive loss as there is no future alternative use for the intellectual property licensed. Merck License Agreement In September 2010, the Company entered into an exclusive license agreement with Schering Corporation, subsequently acquired by Merck & Co., Inc., or Merck, which provides the Company with the exclusive right to develop and commercialize Sarasar (lonafarnib). As consideration for such exclusive right, the Company issued 27,350 shares of Series A convertible preferred stock with a fair value of $500,000 when the agreement was executed in September 2010. In addition, the Company is obligated to pay Merck up to an aggregate of $27.0 million in development milestones and will be required to pay tiered royalties based on aggregate annual net sales of all licensed products ranging from mid-single to low double-digit royalties on net sales. The Company’s obligation to pay royalties to Merck expires on a country-by-country and product-by-product basis on the later of the expiration of the last to expire patent assigned to the Company under the agreement, which is estimated to be in December 2016; or on the tenth anniversary of the first commercial sale of the product. In May 2015, the first regulatory milestone was achieved and the Company paid the related milestone payment of $1.0 million to Merck. The amount has been recorded as a charge to research and development expense during the nine months ended September 30, 2015. No additional charges were recorded during the nine months ended September 30, 2016. Janssen License Agreement In December 2014, the Company entered into a license agreement with Janssen Pharmaceutica NV, (“Janssen”). In connection with this license agreement, the Company is obligated to make development milestone payments in aggregate of up to $38.0 million, sales milestone payments in aggregate up to $65.8 million and will be required to pay tiered royalties based on aggregate annual net sales of all licensed products ranging from mid-single to low double-digit royalties of net sales. As of September 30, 2016, the product has not reached any development milestones nor achieved regulatory approval.

Asset Purchase Agreements and R

Asset Purchase Agreements and Related License Agreements	9 Months Ended
	Sep. 30, 2016
Text Block [Abstract]
Asset Purchase Agreements and Related License Agreements	6. Asset Purchase Agreements and Related License Agreements EGI Asset Purchase Agreement In December 2010, the Company entered into an asset purchase agreement with Eiger Group International, Inc. (“EGI”). Dr. Jeffrey Glenn, a founder and director of the Company, is the sole owner of EGI. Pursuant to the agreement, the Company purchased all of the assets related to the use of farnesyl transferase inhibitors as anti-viral agents and methods to treat viral infections with those inhibitors and inhibitors of prenylation, prenyl cysteine methyltranferase and a protease that removes the XXX tripeptide from the CXXX polypeptide following prenylation including any related intellectual property to EGI. The Company paid EGI an upfront payment of $350,000 when the agreement was executed in December 2010. Additionally, the Company will pay a low single digit royalty of future aggregate annual net sales if the Company has not recouped the development costs of any drug product that incorporates clemizole. Once the costs have been recouped, the Company will pay a low single digit royalty of future aggregate annual net sales if there is no generic competition for the product and a low single digit royalty of future aggregate annual net sales if there is generic competition for the product. Within the first ten years after commercialization, the Company may make a one-time payment of $500,000 for each contract for the three types of product related to such intellectual property that would reduce the payment term for the three products to the tenth anniversary of the first commercial sale. The obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either when the product is no longer sold in any country or the earliest of the tenth anniversary of the first commercial sale of the product. As of September 30, 2016, the product has not achieved regulatory approval. In November 2012, the Company entered into an agreement with EGI whereby the Company sold all of the assets related to the compound clemizole, including any related intellectual property. EGI will pay to the Company a high single digit royalty on future aggregate annual net sales, subject to certain reductions and exceptions. EGI’s obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either expiration of the last to expire patent sold to EGI under the agreement or the earliest of the tenth anniversary of the first commercial sale of the product. As of September 30, 2016, the product has not achieved regulatory approval. Exendin Purchase Agreement and Related Stanford License Agreement In September 2015, the Company entered into an asset purchase agreement with two individuals, Drs. Tracey McLaughlin and Colleen Craig, (the “Sellers”), whereby the Company purchased all of the assets related to the compound exendin including any related intellectual property from the Sellers (the “Exendin APA”). The Company also entered into a consulting agreement with the Sellers as part of the agreement. The Company issued 15,378 shares of common stock that were valued at $211,000 and options to purchase 46,134 shares of common stock with an exercise price of $2.06 per share when the agreement was executed in September 2015. Of the 46,134 options to purchase common stock, 15,378 shares vest monthly over four years as services are provided by the Sellers and 30,756 vest upon the earlier of the first commercial sale of the product or the approval of new drug application by the U.S. Food and Drug Administration (the milestone-vested options). On March 22, 2016, immediately following the closing of the Merger, the Company issued additional “top-up” options to Drs. Tracey McLaughlin and Colleen Craig to purchase an aggregate of 48,544 shares of common stock, pursuant to the terms of the Exendin APA, with an exercise price of $17.25 per share. The top-up options consist of both time-vested and milestone-vested options. The fair value of the time-vested options is recognized as non-employee share-based compensation expense as the awards vest over time, with the unvested portion revalued each period. The fair value of the milestone-vested options will be recognized as research and development expense when it is probable that the earliest milestone will be achieved at their then fair value. During the three months ended September 30, 2016 and 2015, the Company recognized $26,000 and $1,000 of non-employee compensation expense related to the time-vested options, respectively. During the nine months ended September 30, 2016 and 2015, the Company recognized $254,000 and $1,000 of non-employee compensation expense related to the time-vested options, respectively. No expense was recognized for the milestone vested options during the three and nine months ended September 30, 2016 and 2015. The Company is also obligated to pay development milestone payments in an aggregate amount of up to $1.0 million to each Seller. Additionally, the Company is obligated to pay each Seller royalties of low single digits based on aggregate annual net sales of all products developed based on exendin, subject to certain reductions and exceptions. The Company’s obligation to pay royalties expires on the expiration of the last to expire patent assigned to the Company under the agreement. Additionally, the Company has assumed the license agreement the Sellers had previously entered into with the Board of Trustees of the Leland Stanford Junior University (“Stanford”). Prior to the consummation of the Merger, Stanford was a holder of preferred stock of the Company, which converted into shares of common stock upon the consummation of the Merger. The Company is obligated to pay a royalty to Stanford in the low single digits on annual net sales after the first commercial sale of any products developed based on exendin. As of September 30, 2016, the Company had not reached any of the milestone events. Eiccose Purchase Agreement and Related Stanford and Nippon License Agreements In October 2015, the Company entered into an asset purchase agreement with Eiccose, LLC., or Eiccose, whereby Eiccose sold all of the assets related to the treatment of pulmonary arterial hypertension, or PAH, treatment of lymphedema and products containing ubenimex for the treatment of disorders involving LTB4, and any related intellectual property to the Company (the “Eiccose APA”). David Cory, the President, Chief Executive Officer and a director of the Company, is a managing member and significant equity interest holder of Eiccose. The Company made a payment to Eiccose of $120,000 representing reimbursement of certain previously incurred expenses, including payments and accrued amounts owed to Stanford in connection with the license agreement for the treatment of Lymphedema (the “Lymphedema License Agreement”) and the license agreement for the treatment of PAH (the “PAH License Agreement”). The Eiccose APA also provided that, upon a next round of financing pursuant to which the Company sells shares of capital stock resulting in gross proceeds to the Company of at least $25.0 million, the Company would issue to Eiccose fully vested shares of the Company’s common stock equal to 1.75% of the total number of the Company’s outstanding capital stock. In October 2015, the Company recorded $1.5 million in research and development expenses and a corresponding liability representing the fair value of the Company’s obligation to issue common stock to Eiccose. On March 22, 2016, the Company issued to Eiccose 96,300 fully vested shares of the Company’s common stock pursuant to the terms of the Eiccose APA. In connection with this transaction the Company remeasured the fair value of the obligation to issue common stock at the settlement date and the change in fair value of $204,000 was recognized within other income (expense), net in the unaudited condensed consolidated statement of operations and comprehensive loss during the three months ended March 31, 2016. Upon the settlement of the obligation with the issuance of shares on March 22, 2016, the liability was reclassified to common stock and additional paid-in capital within stockholders’ equity. The Company is also obligated to pay to Eiccose an aggregate of $10.0 million of commercial milestones in connection with future sales of the product and royalties in the low single digits based on aggregate annual net sales following the first commercial sale of any product. As of September 30, 2016, the product has not reached any development milestones nor achieved regulatory approval. In addition, as a result of this agreement, the Company has assumed the license agreements Eiccose had previously entered into. These include the PAH License Agreement, the Lymphedema License Agreement for the treatment of lymphedema and the license agreement with Nippon Kayaku Co., Ltd, (“Nippon”). As part of the agreement, Nippon is obligated to make a payment for royalties in the low single digits of sales to the Company. In connection with the PAH License Agreement and the Lymphedema License Agreement, the Company is obligated to make milestone payments of up to $500,000 in the aggregate under each contract, increasing annual license maintenance fees ranging from $10,000 to $75,000 over the term of each license agreement and royalty payments in low single digits on annual net sales after the first commercial sale of a product under each license. For the three and nine months ended September 30, 2016, no amounts have been recorded to research and development expense in connection with the Eiccose APA.

Convertible Promissory Note and

Convertible Promissory Note and Warrant Purchase Agreement	9 Months Ended
	Sep. 30, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Convertible Promissory Note and Warrant Purchase Agreement	7. Convertible Promissory Note and Warrant Purchase Agreement On November 12, 2015, the Company entered into a convertible note and warrant purchase agreement (the “Note and Warrant Purchase Agreement”) with three lenders under which the Company issued convertible promissory notes (the “Notes”) for an aggregate principal amount of $6.0 million and warrants exercisable for shares of the Company’s equity securities at a purchase price of $0.11 per share, on a post-Merger and post-Reverse Stock Split basis. The terms of the Notes included a provision whereby the Notes would be automatically converted into equity securities from a qualified financing with proceeds of at least $25.0 million. The terms of the warrants included a provision whereby the warrants would be automatically exercised if the Company consummated a public offering including a reverse merger (“PO”). If the PO did not occur on or prior to February 28, 2016, the warrant coverage amount was equal to 17.5% of the outstanding principal balance of the Notes. The number of warrant shares into which the warrants could be exercised was equal to the warrant coverage amount divided by the per share price of the equity securities sold in a qualified financing for an exercise price of $0.11 per share, on a post-Merger and post-Reverse Stock Split basis. The warrants also include a provision whereby in the event of a PO which would result in the automatic exercise of the warrants and the automatic conversion of the Notes, the exercise price of the warrants would be paid by cancelling any unpaid interest on the Notes. On November 18, 2015, the Company entered into a subscription agreement (the “Subscription Agreement”) with the holders of the Notes and new investors (the “Private Placement”) for the sale of 2,304,430 shares of its common stock at purchase price of $17.14 per share for total gross proceeds of $39.5 million. The proceeds were comprised of approximately $6.0 million from the conversion of the Notes and approximately $33.5 million of cash. The Company allocated the aggregate proceeds from the issuance of the Notes first to the warrants based on the warrants’ fair value and then the residual proceeds were allocated to the debt obligation. As of December 31, 2015 the fair value of warrants of $885,000 was recorded as a debt discount to be amortized as interest expense over the term of the Note using the effective interest rate method. The fair value of the warrants was also recorded as a corresponding warrant liability. In addition, the Company incurred debt issuance costs of $21,000 in connection with the Note and Warrant Purchase Agreement. The debt issuance costs was being amortized to interest expense over the term of the Note using the effective interest rate method. Upon the closing of the Private Placement on March 22, 2016, immediately prior to the closing of the Merger, the outstanding balance of the Notes totaling approximately $6.0 million was converted into 350,040 shares of the Company’s common stock. The warrants were exercised for 61,254 shares of the Company’s common stock. During the three and nine months ended September 30, 2016, the Company recognized a loss related to the change in fair value of the warrants of $0 and $165,000, respectively. The warrant liability was reclassified to common stock and additional paid-in capital within stockholders’ equity, upon the exercise of the warrants and issuance of shares on March 22, 2016. For the three and nine months ended September 30, 2016, the Company recognized $0 and $685,000, respectively, related to the accrued interest and amortization of the debt discount within interest expense on the Company’s unaudited condensed consolidated statements of operations and comprehensive loss. The discount was fully amortized upon the conversion of the Notes.

Stockholder's Equity

Stockholder's Equity	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Stockholder's Equity	8. Stockholder’s Equity Common Stock Immediately prior to the effective date of the Merger, the principal and outstanding balance of the Notes was converted into shares of the Company’s common stock. In addition, common stock warrants were also exercised and all outstanding preferred stock of the Company converted into common stock. On August 23, 2016, the Company completed an underwritten public offering of 1,250,000 shares of its common stock at a public offering price of $16.00 per share. Total gross proceeds from the offering were $20.0 million, before deducting underwriting discounts and commissions and estimated offering expenses totaling approximately $1.8 million. All of the shares were sold by the In June 2016, the Company entered into a Controlled Equity Offering Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor Fitzgerald”), as a sales agent pursuant to which the Company may offer and sell from time to time, through Cantor Fitzgerald shares of the Company’s common stock, par value $0.001 per share, having an aggregate offering price of up to $25.0 million. The minimum share price for this Controlled Equity Offering is selected at the discretion of the Company’s Board of Directors. Through September 30, 2016, no shares of common stock have been sold pursuant to this Sales Agreement. Private Placement On November 18, 2015, Eiger entered into the Subscription Agreement, pursuant to which Eiger agreed to sell, prior to the consummation of the Merger, 2,304,430 shares of Eiger common stock to certain current stockholders and new investors of Eiger at a purchase price of $17.14 per share for aggregate gross proceeds of $39.5 million, including the conversion of the Notes. In March 2016, immediately prior to closing of the Merger the Company completed the Private Placement and issued an aggregate of 2,304,430 shares common stock in consideration for the conversion of the Notes and cash proceeds of approximately $33.5 million. Further, all outstanding warrants issued in connection with the Promissory Notes were exercised for shares of common stock (see Note 7) and all shares of preferred stock of Eiger converted into shares of common stock of Eiger. At the effective date of the Merger, each outstanding share of the Company’s common stock was converted into the right to receive approximately 0.09 shares of Celladon common stock. Warrants The Company issued warrants to purchase equity securities of the Company in connection with the issuance of the Notes (see Note 7). As of December 31, 2015 the Company accounted for these warrants as a liability at fair value as the number of shares were not fixed and determinable at the issuance date. The Company adjusted the liability for changes in fair value until the exercise of the warrant in March, 2016, when the number of shares to be exercised became fixed, and the warrants were automatically exercised for shares of common stock. The warrant liability was immediately reclassified to common stock and additional paid in capital within stockholders’ deficit. The change in fair value of the warrant liability was recognized as a component of other expense, net in the unaudited condensed consolidated statements of operations and comprehensive loss. The Company assumed from Celladon fully exercisable warrants outstanding for the purchase of 10,180 shares of common stock. The warrants have an exercise price of $84.15 and expire in October 2018.

Stock Based Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	9. Stock Based Compensation As discussed in Note 4, the Company assumed all of the outstanding options, whether or not vested, under the Eiger Plan, with such options henceforth representing the right to purchase a number of shares of the Company’s common stock equal to approximately 0.09 multiplied by the number of shares of Eiger common stock previously represented by such options. For accounting purposes, however, the Company is deemed to have assumed the Celladon 2013 Equity Incentive Plan. Because the Company is considered to be the acquirer for accounting purposes, the pre-Merger vested stock options granted by Celladon are deemed to have been exchanged for equity awards of the Company and, as such, the portion of the acquisition date fair value of these equity awards attributable to pre-Merger service to Celladon were accounted for as a component of the consideration transferred, which was not material to the unaudited condensed consolidated financial statements. The exchange of options to purchase shares of Eiger common stock for options to purchase shares of the Combined Company, was accounted for as a modification of the awards because the legal exchange of the awards is considered a modification of Eiger stock options. 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. In June 2016, the Company’s board of directors adopted and in August 2016 the Company’s stockholders approved the amended and restated 2013 Equity Incentive Plan(the “ Restated 2013 Plan”), which increased the number of shares reserved for grant by 1,296,683 shares. Under the terms of the Restated 2013 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then employees, officers, non-employee directors or consultants of the Company. All awards granted prior to the approval of the Restated 2013 Plan remain subject to the terms of the previous plans and the applicable award agreements. The following table summarizes stock option activity under the Company’s stock based compensation plan during the nine months ended September 30, 2016 (in thousands, except share data): Number of Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value Outstanding as of December 31, 2015 254,058 $ 1.94 $ 3,369 Options assumed in the merger 37,276 $ 177.57 Granted 862,572 $ 16.20 Exercised (7,034 ) $ 5.93 Canceled (22,828 ) $ 224.21 Outstanding as of September 30, 2016 1,124,044 $ 14.17 9.59 $ 2,848 Vested and expected to vest as of September 30, 2016 1,076,796 $ 14.19 9.59 $ 2,752 Vested and exercisable as of September 30, 2016 179,031 $ 16.77 8.97 $ 922 Stock Options Granted to Employees During the three and nine months ended September 30, 2016, the Company granted employees stock options for 814,028 shares and the weighted-average grant date fair value of these options was $10.58. The weighted-average grant date fair value of the options granted during the three and nine months ended September 30, 2015 was $12.40 and $12.21, respectively. The Company records stock-based compensation of stock options granted to employees by estimating the fair value of stock-based awards using the Black-Scholes option pricing model and amortizing the fair value of the stock-based awards granted over the applicable vesting period of the awards on a straight-line basis. The fair value of employee stock options was estimated using the following weighted-average assumptions: Three and Nine Months Ended September 30, 2016 2015 Expected term (in years) 5.27-6.08 5.00-6.08 Volatility 73.91%-77.09% 77.58%-97.62% Risk free interest rate 1.21%-1.31% 1.44%-1.75% Dividend yield — — Stock Options Granted to Non-Employees The Company grants stock options to non-employees in exchange for services rendered. During the three and nine months ended September 30, 2016, the Company granted to non-employees stock options for 0 and 48,544 shares, respectively. During the three and nine months ended September 30, 2015, the Company granted to non-employees stock options for 46,134 shares. Stock-based compensation expense related to stock options granted to non-employees is recognized as the stock options are earned and will fluctuate as the estimated fair value of the common stock fluctuates until the awards vest. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered. The fair value of the stock options granted to non-employees is calculated at each reporting date using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Expected term (in years) 7.0-9.67 8.0-10.0 7.0-10.0 8.0-10.0 Volatility 84.42%-96.38% 86.16%-89.32% 84.42%-96.38% 86.16%-89.32% Risk free interest rate 1.40%-1.60% 1.84%-2.14% 1.37%-2.04% 1.73%-2.23% Dividend yield — — — — Stock-Based Compensation Expense Total stock-based compensation expense recognized for options granted to employees and non-employees was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Research and development $ 126 $ 8 $ 428 $ 12 General and administrative 1,114 14 1,323 60 Total $ 1,240 $ 22 $ 1,751 $ 72 As of September 30, 2016, the total unrecognized compensation expense related to unvested employee options was $9.1 million, which the Company expects to recognize over an estimated weighted average period of 3.1 years.

Legal Matters

Legal Matters	9 Months Ended
	Sep. 30, 2016
Commitments And Contingencies Disclosure [Abstract]
Legal Matters	10. Legal Matters In July 2015, three putative securities class action complaints (captioned Fialkov v. Celladon Corporation, Case No. 15-cv-1458-AJB-DHB, Lorusso v. Celladon Corporation, Case No. 15-cv-1501-L-JLB and Jacobs v. Celladon Corporation, Case No. 15-cv-1529-AJB-MDD) were filed in the U.S. District Court for the Southern District of California against Celladon and certain of Celladon’s current and former officers. The complaints generally allege that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, or the Exchange Act, by making materially false and misleading statements regarding the clinical trial program for MYDICAR, thereby artificially inflating the price of Celladon’s common stock. The complaints seek unspecified monetary damages and other relief, including attorneys’ fees. On September 1, 2015, six stockholders (or groups of stockholders) filed motions to consolidate the three putative securities class actions and to appoint lead plaintiffs (the “Motions to Consolidate”). A hearing on the Motions to Consolidate was held on December 3, 2015. On December 9, 2015, the Court consolidated the three putative securities class actions and appointed a lead plaintiff to represent the putative class. The lead plaintiff filed a consolidated amended complaint on February 29, 2016. On April 29, 2016, the defendants, including Eiger, filed a motion to dismiss the consolidated amendment complaint. On June 28, 2016, lead plaintiff filed his opposition to the motion to dismiss the consolidated amended complaint. On July 28, 2016, the defendants filed their reply in support of the motion to dismiss. On October 7, 2016, the Court entered an order granting the Company’s motion to dismiss with leave to amend. On October 18, 2016 lead plaintiff filed a notice that stated he does not intend to amend the complaint, an upon the Court’s entry of judgment in favor of defendants, lead plaintiff will file a notice to appeal to the United States Court of Appeals for the Ninth Circuit. The Company believes that it has meritorious defenses and intends to defend these lawsuits vigorously. Due to the early stage of these proceedings, the Company is not able to predict or reasonably estimate the ultimate outcome or possible losses relating to these claims.

Income taxes

Income taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income taxes	11. Income taxes Our tax expense for the three and nine months ended September 30, 2016 was zero due to our loss position and full valuation allowance. This is consistent with our zero tax expense for the three and nine months ended September 30, 2015.

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of Eiger BioPharmaceuticals, Inc. and its wholly owned subsidiaries, EBPI Merger Inc., EB Pharma LLC and Eiger BioPharmaceuticals Europe Limited, and have been prepared in accordance with accounting principles generally accepted in the United States of America, (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s financial information. These interim results are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for any other interim period or for any other future year. The balance sheet as of December 31, 2015 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. All intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto contained in the Company’s Form 8-K/A and Form 8-K/A Amendment No.2 for the year ended December 31, 2015, filed with the Securities and Exchange Commission on May 13, 2016 and June 17, 2016, respectively.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to clinical trial accrued liabilities, stock-based compensation and income taxes. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Accrued Research and Development Costs	Accrued Research and Development Costs The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided, but not yet invoiced, and includes these costs in accrued liabilities in the unaudited condensed consolidated balance sheets and within research and development expense in the unaudited condensed consolidated statements of operations and comprehensive loss. These costs are a significant component of the Company’s research and development expenses. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred and consist of payroll expenses, stock-based compensation expense, lab supplies and allocated facility costs, as well as fees paid to third parties that conduct certain research and development activities on the Company’s behalf. Amounts incurred in connection with license and asset purchase agreements are also included in research and development expense.
Stock-Based Compensation Expense	Stock-Based Compensation Expense Stock-based awards to employees and directors, including stock options, are recorded at fair value as of the grant date using the Black-Scholes option pricing model and recognized as expense on a straight line-basis over the employee’s or director’s requisite service period (generally the vesting period). Non-cash stock compensation expense is based on awards ultimately expected to vest and is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. The determination of fair value for stock-based awards on the date of grant using an option pricing model requires management to make certain assumptions regarding subjective variables. Stock-based awards and stock options issued to non-employee consultants are recorded at fair value and remeasured at the end of each period as they vest using the Black-Scholes option pricing model. Expense is recognized over the vesting period which is generally the same as the service period.
Net Loss per Share	Net Loss per Share Basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net loss per share because including such securities would be anti-dilutive (in common stock equivalent shares): Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Options to purchase common stock 1,124,044 260,184 1,124,044 260,184 Warrants to purchase common stock 10,180 — 10,180 — Convertible preferred stock — 2,609,102 — 2,609,102 Total 1,134,224 2,869,286 1,134,224 2,869,286
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board, (“FASB”), issued Accounting Standards Update, (“ASU”), ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) On February 25, 2016 the FASB issued ASU 2016-02, Leases (Topic 842), In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings per Share	The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net loss per share because including such securities would be anti-dilutive (in common stock equivalent shares): Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Options to purchase common stock 1,124,044 260,184 1,124,044 260,184 Warrants to purchase common stock 10,180 — 10,180 — Convertible preferred stock — 2,609,102 — 2,609,102 Total 1,134,224 2,869,286 1,134,224 2,869,286

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): December 31, 2015 Level 1 Level 2 Level 3 Total Financial liabilities: Warrant liability $ — $ — $ 885 $ 885 Obligation to issue common stock $ — $ — $ 1,457 $ 1,457 Total $ — $ — $ 2,342 $ 2,342
Reconciliation of Liabilities Measured at Fair Value Using Level 3 Significant Unobservable Inputs	The following table provides a reconciliation of liabilities measured at fair value using Level 3 significant unobservable inputs (in thousands) for the nine months ended September 30, 2016: Nine Months Ended September 30, 2016 Balance, beginning of period $ 2,342 Change in fair value of common stock warrants and obligation to issue common stock to Eiccose (1) 369 Settlement of warrant liability upon exercise of common stock warrants (1,050 ) Settlement of Eiccose obligation upon issuance of common stock (1,661 ) Balance, end of period $ — (1) Changes in fair value of the obligation to issue common stock are recorded in other expense, net on the accompanying unaudited condensed consolidated statements of operations and comprehensive loss.

Reverse Merger (Tables)

Reverse Merger (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Summary of Net Assets Acquired Based on Estimated Fair Values	The following table summarizes the net assets acquired based on their estimated fair values as of March 22, 2016 (in thousands): Cash $ 28,018 Prepaid and other assets 198 Current liabilities (857 ) Non-current liabilities (12 ) Net acquired tangible assets 27,347 Estimated total purchase consideration $ 27,347

Stock Based Compensation (Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2016
Stock Option Activity	The following table summarizes stock option activity under the Company’s stock based compensation plan during the nine months ended September 30, 2016 (in thousands, except share data): Number of Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value Outstanding as of December 31, 2015 254,058 $ 1.94 $ 3,369 Options assumed in the merger 37,276 $ 177.57 Granted 862,572 $ 16.20 Exercised (7,034 ) $ 5.93 Canceled (22,828 ) $ 224.21 Outstanding as of September 30, 2016 1,124,044 $ 14.17 9.59 $ 2,848 Vested and expected to vest as of September 30, 2016 1,076,796 $ 14.19 9.59 $ 2,752 Vested and exercisable as of September 30, 2016 179,031 $ 16.77 8.97 $ 922
Summary of Non-cash Stock Based Compensation Expense	Total stock-based compensation expense recognized for options granted to employees and non-employees was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Research and development $ 126 $ 8 $ 428 $ 12 General and administrative 1,114 14 1,323 60 Total $ 1,240 $ 22 $ 1,751 $ 72
Employees Stock Option [Member]
Fair Value of Stock Option Granted Using Black-Scholes Option Pricing Model	The fair value of employee stock options was estimated using the following weighted-average assumptions: Three and Nine Months Ended September 30, 2016 2015 Expected term (in years) 5.27-6.08 5.00-6.08 Volatility 73.91%-77.09% 77.58%-97.62% Risk free interest rate 1.21%-1.31% 1.44%-1.75% Dividend yield — —
Non-Employees Stock Option [Member]
Fair Value of Stock Option Granted Using Black-Scholes Option Pricing Model	The fair value of the stock options granted to non-employees is calculated at each reporting date using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Expected term (in years) 7.0-9.67 8.0-10.0 7.0-10.0 8.0-10.0 Volatility 84.42%-96.38% 86.16%-89.32% 84.42%-96.38% 86.16%-89.32% Risk free interest rate 1.40%-1.60% 1.84%-2.14% 1.37%-2.04% 1.73%-2.23% Dividend yield — — — —

Description of Business - Addit

Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands	Aug. 23, 2016USD ($)$ / sharesshares	Mar. 22, 2016USD ($)$ / sharesshares	Sep. 30, 2016USD ($)Segment	Dec. 31, 2015USD ($)
Description Of Business [Line Items]
Entity incorporation, date of incorporation			Nov. 6, 2008
Number of operating segments | Segment			1
Reverse stock split, description			Fifteen-for-one reverse stock split of its common stock
Reverse stock split ratio			15
Agreement entered date			Nov. 18, 2015
Accumulated deficit			$ (63,590)	$ (29,271)
Underwritten Public Offering [Member]
Description Of Business [Line Items]
Proceeds from issuance of common stock	$ 20,000
Underwriting discounts and commissions and estimated offering expenses	1,800
Reverse Stock Split [Member]
Description Of Business [Line Items]
Common stock exchange price per share | $ / shares		$ 0.09
Combined shares of common stock outstanding | shares		6,945,401
Liquidity [Member]
Description Of Business [Line Items]
Accumulated deficit			$ 63,600
Total net cash acquired from merger		$ 28,000
Proceeds from issuance of common stock		$ 33,500
Liquidity [Member] | Underwritten Public Offering [Member]
Description Of Business [Line Items]
Proceeds from issuance of common stock	$ 20,000
Sale of common stock | shares	1,250,000
Purchase price per share | $ / shares	$ 16
Underwriting discounts and commissions and estimated offering expenses	$ 1,800
Reverse Merger [Member]
Description Of Business [Line Items]
Date of acquisition			Mar. 22, 2016
Reverse Stock Split [Member]
Description Of Business [Line Items]
Reverse stock split ratio		15
Issuance of common stock in connection with acquisition | shares		0

Summary of Significant Accoun24

Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	1,134,224	2,869,286	1,134,224	2,869,286
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	10,180		10,180
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	1,124,044	260,184	1,124,044	260,184
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities		2,609,102		2,609,102

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Financial liabilities:
Warrant liability	$ 885
Obligation to issue common stock	1,457
Total	2,342
Level 3 [Member]
Financial liabilities:
Warrant liability	885
Obligation to issue common stock	1,457
Total	$ 2,342

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Level 3 Significant Unobservable Inputs (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Balance, beginning of period	$ 2,342
Change in fair value of common stock warrants and obligation to issue common stock to Eiccose	369
Settlement of warrant liability upon exercise of common stock warrants	(1,050)
Settlement of Eiccose obligation upon issuance of common stock	$ (1,661)

Reverse Merger - Additional Inf

Reverse Merger - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 22, 2016	Sep. 30, 2016
Reverse Merger Transactions [Line Items]
Estimated fair value of assets	$ 27,347
Reverse Stock Split [Member]
Reverse Merger Transactions [Line Items]
Common stock exchange price per share	$ 0.09
Combined shares of common stock outstanding	6,945,401
Celladon Europe [Member]
Reverse Merger Transactions [Line Items]
Combined shares of common stock outstanding	1,600,000
Percentage of shares acquired by share holders of Celladon	22.00%
Market capitalization	$ 27,500
Estimated fair value of assets	$ 27,300
Eiger BioPharmaceuticals, Inc [Member]
Reverse Merger Transactions [Line Items]
Percentage of shares acquired by stock holders, warrant holders and option holders after merger	78.00%
Reverse Merger [Member]
Reverse Merger Transactions [Line Items]
Date of acquisition		Mar. 22, 2016
Reverse Merger [Member] | Celladon Europe [Member]
Reverse Merger Transactions [Line Items]
Ownership percentage	78.00%

Reverse Merger - Summary of Net

Reverse Merger - Summary of Net Assets Acquired Based on Estimated Fair Values (Detail) $ in Thousands	Mar. 22, 2016USD ($)
Business Combinations [Abstract]
Cash	$ 28,018
Prepaid and other assets	198
Current liabilities	(857)
Non-current liabilities	(12)
Net acquired tangible assets	27,347
Estimated total purchase consideration	$ 27,347

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	Apr. 20, 2016	Apr. 30, 2016	May 31, 2015	Dec. 31, 2014	Sep. 30, 2010	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate fair value of shares issued						$ 8,000
Fair value of shares issued								$ 22,567,000
Common Stock [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sale of common stock						1,250,000
BMS Transaction [Member] | Common Stock [Member] | BMS Purchase Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Sale of common stock	157,587
Aggregate fair value of shares issued		$ 3,200,000
BMS Transaction [Member] | Licensing Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront payment	$ 2,000,000	$ 2,000,000
BMS Transaction [Member] | Licensing Agreements [Member] | Development [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payment obligations	61,000,000
BMS Transaction [Member] | Licensing Agreements [Member] | Sales [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payment obligations	128,000,000
BMS Transaction [Member] | Licensing Agreements [Member] | Common Stock [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
New shares issued during period, value upfront payment	$ 3,000,000
Merck Transaction [Member] | Licensing Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalties expiration description						The Company’s obligation to pay royalties to Merck expires on a country-by-country and product-by-product basis on the later of the expiration of the last to expire patent assigned to the Company under the agreement, which is estimated to be in December 2016; or on the tenth anniversary of the first commercial sale of the product.
Milestone payments			$ 1,000,000			$ 0	$ 0
Merck Transaction [Member] | Licensing Agreements [Member] | Series A- Convertible Preferred Stock [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Shares issued					27,350
Fair value of shares issued					$ 500,000
Merck Transaction [Member] | Licensing Agreements [Member] | Development [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development milestone payment obligations					$ 27,000,000
Janssen Transaction [Member] | Licensing Agreements [Member] | Development [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payment obligations				$ 38,000,000
Janssen Transaction [Member] | Licensing Agreements [Member] | Sales [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payment obligations				$ 65,800,000

Asset Purchase Agreements and30

Asset Purchase Agreements and Related License Agreements - Additional Information (Detail) - USD ($)	Mar. 22, 2016	Oct. 31, 2015	Sep. 30, 2015	Dec. 31, 2010	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Asset Purchase Agreement And Related License Agreement [Line Items]
Compensation expense related to the time-vested/milestone vested options					$ 1,240,000		$ 22,000	$ 1,751,000	$ 72,000
Research and development expense					8,072,000		2,110,000	23,637,000	4,493,000
Eiccose Purchase Agreement [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Aggregate potential milestone payments	$ 10,000,000
Reimbursement of expenses incurred		$ 120,000
Gross proceeds to company's capital stock		$ 25,000,000
Share based compensation issued and outstanding shares percentage		1.75%
Research and development expense		$ 1,500,000
Number of fully vested shares issued	96,300
Change in fair value recognized in other income (expense)						$ 204,000
Maximum [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Aggregate potential milestone payments								1,000,000
Share-based Compensation Award, Tranche Two [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Compensation expense related to the time-vested/milestone vested options					0		0	0	0
Share-based Compensation Award, Tranche One [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Compensation expense related to the time-vested/milestone vested options					26,000		$ 1,000	$ 254,000	$ 1,000
Asset Purchase Agreement [Member] | EIG Transaction [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Upfront payment				$ 350,000
Asset purchase description								Within the first ten years after commercialization, the Company may make a one-time payment of $500,000 for each contract for the three types of product related to such intellectual property that would reduce the payment term for the three products to the tenth anniversary of the first commercial sale.
One-time payment				$ 500,000
Asset Purchase Agreement [Member] | EIG Transaction [Member] | Farnesyl Transferase Inhibitors and Related Intellectual Property [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Royalties expiration description								The obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either when the product is no longer sold in any country or the earliest of the tenth anniversary of the first commercial sale of the product.
Asset Purchase Agreement [Member] | EIG Transaction [Member] | Clemizole and Related Intellectual Property [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Royalties expiration description								EGI’s obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either expiration of the last to expire patent sold to EGI under the agreement or the earliest of the tenth anniversary of the first commercial sale of the product.
Exendin Purchase Agreement [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Common stock, value			$ 211,000
Options to purchase common stock	48,544		46,134
Options to purchase of common stock exercise price	$ 17.25		$ 2.06				$ 2.06		$ 2.06
Options to purchase common stock vesting period			4 years
Exendin Purchase Agreement [Member] | Share-based Compensation Award, Tranche Two [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Shares issued for purchased assets			15,378
Exendin Purchase Agreement [Member] | Share-based Compensation Award, Tranche One [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Vesting of options to purchase common stock			$ 30,756
Licensing Agreements [Member] | Eiccose Purchase Agreement [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Research and development expense					0			$ 0
Licensing Agreements [Member] | Maximum [Member] | Eiccose Purchase Agreement [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Aggregate potential milestone payments								500,000
Annual sublicense maintenance fee payable					75,000			75,000
Licensing Agreements [Member] | Minimum [Member] | Eiccose Purchase Agreement [Member]
Asset Purchase Agreement And Related License Agreement [Line Items]
Annual sublicense maintenance fee payable					$ 10,000			$ 10,000

Convertible Promissory Note a31

Convertible Promissory Note and Warrant Purchase Agreement - Additional Information (Detail)	Mar. 22, 2016USD ($)shares	Nov. 18, 2015USD ($)$ / sharesshares	Nov. 12, 2015USD ($)Lender$ / shares	Mar. 31, 2016shares	Dec. 31, 2015USD ($)	Sep. 30, 2016USD ($)$ / shares	Sep. 30, 2016USD ($)$ / sharesshares
Convertible Promissory Note [Line Items]
Warrant exercise price | $ / shares						$ 84.15	$ 84.15
Fair value of warrants					$ 885,000	$ 0	$ 165,000
Warrants exercisable date							Mar. 22, 2016
Interest Expense [Member]
Convertible Promissory Note [Line Items]
Accrued interest						0	$ 685,000
Amortization of debt discount						$ 0	$ 685,000
Private Placement [Member]
Convertible Promissory Note [Line Items]
Proceeds from sale of common stock		$ 39,500,000
Outstanding balance of notes	$ 6,000,000
Private Placement [Member] | Cash [Member]
Convertible Promissory Note [Line Items]
Proceeds from sale of common stock		33,500,000
Convertible Debt [Member] | Private Placement [Member]
Convertible Promissory Note [Line Items]
Proceeds from sale of common stock		$ 6,000,000
Common Stock [Member]
Convertible Promissory Note [Line Items]
Sale of common stock | shares							1,250,000
Conversion of warrants | shares	61,254
Common Stock [Member] | Private Placement [Member]
Convertible Promissory Note [Line Items]
Purchase price per share | $ / shares		$ 17.14
Sale of common stock | shares		2,304,430		2,304,430
Notes converted in to common stock | shares	350,040
Convertible Promissory Note and Warrant Purchase Agreement [Member]
Convertible Promissory Note [Line Items]
Number of lenders | Lender			3
Proceeds from equity securities			$ 25,000,000
Debt issuance cost							$ 21,000
Convertible Promissory Note and Warrant Purchase Agreement [Member] | If the PO or Reverse Merger did not occur by February 28, 2016 [Member]
Convertible Promissory Note [Line Items]
Percentage of warrant equals outstanding principal balance of notes						17.50%	17.50%
Convertible Promissory Note and Warrant Purchase Agreement [Member] | Convertible Debt [Member]
Convertible Promissory Note [Line Items]
Proceeds from sale of common stock			$ 6,000,000
Convertible Promissory Note and Warrant Purchase Agreement [Member] | Warrants to Purchase Common Stock [Member]
Convertible Promissory Note [Line Items]
Purchase price per share | $ / shares			$ 0.11
Warrant exercise price | $ / shares			$ 0.11

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Aug. 23, 2016	Nov. 18, 2015	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 22, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock aggregate offering price								$ 1,457,000
Warrants outstanding				10,180	10,180
Warrants outstanding, Exercise Price				$ 84.15	$ 84.15
Warrants outstanding, Expiration Date					2018-10
Reverse Stock Split [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock exchange price per share							$ 0.09
Underwritten Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from sale of common stock	$ 20,000,000
Underwriting discounts and commissions and estimated offering expenses	$ 1,800,000
Sales Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value						$ 0.001
Private Placement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from sale of common stock		$ 39,500,000
Private Placement [Member] | Cash [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from sale of common stock		$ 33,500,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock					1,250,000
Common Stock [Member] | Underwritten Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock	1,250,000
Purchase price per share	$ 16
Common Stock [Member] | Sales Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock				0
Common Stock [Member] | Private Placement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock		2,304,430	2,304,430
Purchase price per share		$ 17.14
Maximum [Member] | Sales Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock aggregate offering price						$ 25,000,000

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion rate representing right to purchase number of shares of Company's common stock				0.09%
Stock options granted				862,572
Total unrecognized compensation expense		$ 9.1		$ 9.1
Weighted average period expected to recognized compensation expense (in years)				3 years 1 month 6 days
Employees Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted		814,028	166,791	814,028	169,825
Weighted-average grant date fair value of employee option grants		$ 10.58	$ 12.40	$ 10.58	$ 12.21
Non-Employees Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted		0	46,134	48,544	46,134
Amended and Restated 2013 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased number of shares reserved for grant	1,296,683

Stock Based Compensation - Stoc

Stock Based Compensation - Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)
Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Exercise Price And Additional Disclosures [Abstract]
Number of Options, Outstanding, Beginning balance | shares	254,058
Number of Options, Options assumed in the Merger | shares	37,276
Number of Options, Granted | shares	862,572
Number of Options, Exercised | shares	(7,034)
Number of Options, Canceled | shares	(22,828)
Number of Options, Outstanding, Ending balance | shares	1,124,044
Number of Options, Vested and expected to vest | shares	1,076,796
Number of Options, Vested and exercisable | shares	179,031
Weighted Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 1.94
Weighted Average Exercise Price Per Share, Options assumed in the Merger | $ / shares	177.57
Weighted Average Exercise Price Per Share, Granted | $ / shares	16.20
Weighted Average Exercise Price Per Share, Exercised | $ / shares	5.93
Weighted Average Exercise Price Per Share, Canceled | $ / shares	224.21
Weighted Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	14.17
Weighted Average Exercise Price Per Share, Vested and expected to vest | $ / shares	14.19
Weighted Average Exercise Price Per Share, Vested and exercisable | $ / shares	$ 16.77
Weighted Average Remaining Contractual Life, Ending balance	9 years 7 months 2 days
Weighted Average Remaining Contractual Life, Vested and expected to vest	9 years 7 months 2 days
Weighted Average Remaining Contractual Life, Vested and exercisable	8 years 11 months 19 days
Aggregate Intrinsic Value, Beginning balance | $	$ 2,848	$ 3,369
Aggregate Intrinsic Value, Vested and expected to vest | $	2,752
Aggregate Intrinsic Value, Vested and exercisable | $	$ 922

Stock Based Compensation - Fair

Stock Based Compensation - Fair Value of Stock Option Granted Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employees Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility, minimum	73.91%	77.58%	73.91%	77.58%
Volatility, maximum	77.09%	97.62%	77.09%	97.62%
Risk-free interest rate, minimum	1.21%	1.44%	1.21%	1.44%
Risk-free interest rate, maximum	1.31%	1.75%	1.31%	1.75%
Employees Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 7 days	5 years	5 years 3 months 7 days	5 years
Employees Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days	6 years 29 days	6 years 29 days
Non-Employees Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility, minimum	84.42%	86.16%	84.42%	86.16%
Volatility, maximum	96.38%	89.32%	96.38%	89.32%
Risk-free interest rate, minimum	1.40%	1.84%	1.37%	1.73%
Risk-free interest rate, maximum	1.60%	2.14%	2.04%	2.23%
Non-Employees Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 years	8 years	7 years	8 years
Non-Employees Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	9 years 8 months 1 day	10 years	10 years	10 years

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Non-cash Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 1,240	$ 22	$ 1,751	$ 72
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	126	8	428	12
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 1,114	$ 14	$ 1,323	$ 60

Legal Matters - Additional Info

Legal Matters - Additional Information (Detail)	Feb. 29, 2016PlaintiffClaim	Dec. 09, 2015Claim	Sep. 01, 2015PlaintiffClaim	Jul. 31, 2015Claim
3 Putative Securities Class Action Complaints [Member]
Loss Contingencies [Line Items]
Loss contingency, new claims filed, number				3
Loss contingency, claims consolidated, number		3
Motions to Consolidate [Member]
Loss Contingencies [Line Items]
Loss contingency, number of plaintiffs | Plaintiff			6
Loss contingency, new claims filed, number			1
Loss contingency, claims settled, number		1
Consolidated Amended Complaint [Member]
Loss Contingencies [Line Items]
Loss contingency, number of plaintiffs | Plaintiff	1
Loss contingency, new claims filed, number	1

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Tax expense	$ 0	$ 0	$ 0	$ 0