Pulmatrix (PULM) 10-K 13 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 08, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	PULM
Entity Registrant Name	Pulmatrix, Inc.
Entity Central Index Key	1,574,235
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		22,280,160
Entity Public Float			$ 47,823,941

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,550	$ 4,182
Prepaid expenses and other current assets	696	577
Total current assets	4,246	4,759
Property and equipment, net	614	786
Long-term restricted cash	204	204
Goodwill	10,914	10,914
Total assets	15,978	16,663
Current liabilities:
Loan Payable, net of debt discount and issuance costs	3,221	2,586
Accounts payable	457	747
Accrued expenses	2,162	1,317
Total current liabilities	5,840	4,650
Loan payable, net of current portion, debt discount and issuance costs		3,217
Derivative liability	1	35
Total liabilities	5,841	7,902
Stockholders' Equity:
Common stock, $0.0001 par value - 100,000,000 shares authorized at December 31, 2017 and December 31, 2016; 21,047,498 and 14,850,526 shares issued and outstanding including vested and restricted stock of 0 and 99,308, at December 31, 2017 and December 31, 2016, respectively	2	1
Additional paid-in capital	184,137	164,706
Accumulated deficit	(174,002)	(155,946)
Total stockholders' equity	10,137	8,761
Total liabilities and stockholders' equity	$ 15,978	$ 16,663

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	21,047,498	14,850,526
Common stock, shares outstanding	21,047,498	14,850,526
Restricted Stock [Member]
Common stock, shares outstanding	0	99,308

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 335	$ 835
Operating expenses
Research and development	10,243	10,152
General and administrative	7,567	8,015
Write off of intangibles		7,534
Total operating expenses	17,810	25,701
Loss from operations	(17,475)	(24,866)
Other income (expense)
Interest expense	(643)	(881)
Impairment of goodwill	0	(5,029)
Fair value adjustment of derivative liability	34	(24)
Other income (expense), net	28	(2)
Loss before income taxes	(18,056)	(30,802)
Benefit from income taxes		2,959
Net loss	$ (18,056)	$ (27,843)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.93)	$ (1.88)
Weighted average shares used to compute basic and diluted net loss per share attributable to common stockholders	19,371,564	14,815,230

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated deficit [Member]
Beginning balance at Dec. 31, 2015	$ 32,606	$ 1	$ 160,708	$ (128,103)
Beginning balance, shares at Dec. 31, 2015		14,745,754
Exercise of common stock options, shares		277
Vesting of restricted stock units	1,171		1,171
Vesting of restricted stock units, shares		104,495
Stock-based compensation	2,827		2,827
Net loss	(27,843)			(27,843)
Ending balance at Dec. 31, 2016	8,761	$ 1	164,706	(155,946)
Ending balance, shares at Dec. 31, 2016		14,850,526
Issuance of common stock, net of issuance costs	16,310		16,310
Issuance of common stock, net of issuance costs, shares		6,053,360
Exercise of common stock options	$ 304	$ 1	303
Exercise of common stock options, shares	138,425	138,425
Vesting of restricted stock units, shares		5,187
Stock-based compensation	$ 2,818		2,818
Net loss	(18,056)			(18,056)
Ending balance at Dec. 31, 2017	$ 10,137	$ 2	$ 184,137	$ (174,002)
Ending balance, shares at Dec. 31, 2017		21,047,498

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net loss	$ (18,056)	$ (27,843)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	246	250
Write-off of intangibles, net of tax provision		4,575
Impairment of goodwill	0	5,029
Stock-based compensation	2,818	3,998
Non-cash rent expense	21	43
Non-cash interest expense	171	212
Non-cash debt issuance expense	12	16
Fair value adjustment on derivative liability	(34)	24
Loss on disposal of property and equipment		82
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(119)	983
Accounts payable	(290)	(346)
Accrued expenses	754	(312)
Net cash used in operating activities	(14,477)	(13,243)
Cash flows from investing activities:
Proceeds on sale of equipment		24
Purchases of property and equipment	(74)	(455)
Net cash used in investing activities	(74)	(431)
Cash flows from financing activities:
Proceeds from issuance of common stock and warrants, net	16,310
Proceeds from exercise of stock options	304
Principal payments term loan	(2,695)	(1,046)
Net cash provided by (used in) financing activities	13,919	(1,046)
Net decrease in cash and cash equivalents	(632)	(14,720)
Cash and cash equivalents - beginning of period	4,182	18,902
Cash and cash equivalents- end of period	$ 3,550	4,182
Supplemental disclosures of noncash financing and investing activities:
Fixed asset trade in value		60
Fixed asset purchases in accounts payable at year-end		$ 2

Organization

Organization	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Pulmatrix, Inc. (the “Company”) was incorporated in 2013 as a Nevada corporation and converted to a Delaware corporation in September 2013. On June 15, 2015, the Company completed a merger with Pulmatrix Operating Company, changed its name from Ruthigen, Inc. to “Pulmatrix, Inc.” and relocated its corporate headquarters to Lexington, Massachusetts. The Company is a clinical stage biotechnological company and is focused on the development of novel inhaled therapeutic products intended to prevent and treat respiratory diseases and infections. Liquidity At December 31, 2017, the Company had unrestricted cash of $3.6 million and working capital deficit of $1.6 million. The Company had incurred recurring losses and as of December 31, 2017 had an accumulated deficit of $174 million. The Company has primarily financed operations to date through the sale of equity securities and term loan. The Company will be required to raise additional capital within the next year to continue the development and commercialization of current product candidates and to continue to fund operations at the current cash expenditure levels. These conditions raise substantial doubt about the Company’s ability to continue as a going concern and meet its obligations. During the year ended December 31, 2017, the Company raised an aggregate of $16.3 million in net proceeds through the sale of its common stock (note 9). The Company cannot be certain that additional funding will be available on acceptable terms, or at all. To the extent that the Company raises additional funds by issuing equity securities, the Company’s stockholders may experience significant dilution. Any debt financing, if available, may involve restrictive covenants that impact the Company’s ability to conduct business. If unable to raise additional capital when required or on acceptable terms, the Company may have to (i) delay, scale back or discontinue the development and/or commercialization of one or more product candidates; (ii) seek collaborators for product candidates at an earlier stage than otherwise would be desirable and on terms that are less favorable than might otherwise be available; or (iii) relinquish or otherwise dispose of rights to technologies, product candidates or products that the Company would otherwise seek to develop or commercialize ourselves on unfavorable terms. The Company’s ability to continue as a going concern is dependent upon its ability to obtain additional equity or debt financing and, ultimately, to generate revenue. There will be continued doubt about the Company’s ability to continue as a going concern if the Company is unable to do so. The Company’s consolidated financial statements as of December 31, 2017 do not include any adjustments that might result from the outcome of this uncertainty.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation Principles of Consolidation The consolidated financial statements represent the consolidation of the accounts of the Company and its subsidiary in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”). All intercompany accounts and transactions have been eliminated in consolidation. Recent Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) 2014-09”). 2014-09 605-35, Revenue Recognition - Construction-Type and Production-Type Contracts 2014-09 2014-09 2014-09 2014-09 2014-09 2014-09 2014-09 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date 2014-09 2015-14 In January 2017, the Financial Accounting Standard Board (the “FASB”) issued Accounting Standards Update (ASU) 2017-04: “Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment” 2017-04”), In May 2017, the Financial Accounting Standard Board (the “FASB”) issued Accounting Standards Update (ASU) 2017-09: Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting In July 2017, FASB issued ASU No. 2017-11, 2017-11 470-20, re-characterize Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment. Use of Estimates In preparing consolidated financial statements in conformity with U.S. GAAP, management is required 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, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results may differ from these estimates. On an ongoing basis, the Company evaluates its estimates and assumptions. These estimates and assumptions include valuing equity securities in share-based payments, estimating fair value of equity instruments recorded as derivative liabilities, estimating the useful lives of depreciable and amortizable assets, valuation allowance against deferred tax assets, goodwill impairment, and estimating the fair value of long-lived assets to assess whether impairment charges may apply. Concentrations of Credit Risk Cash is a financial instrument that potentially subjects the Company to concentrations of credit risk. For all periods presented, substantially all of the Company’s cash was deposited in an account at a single financial institution that management believes is creditworthy. The Company is exposed to credit risk in the event of default by these financial institutions for amounts in excess of the Federal Deposit Insurance Corporation insured limits. The Company maintains its cash at a high quality financial institution and has not incurred any losses to date. Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Valuations based on quoted prices for similar assets or liabilities in markets that are not active, or for which all significant inputs are observable, either directly or indirectly. Level 3 — Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The fair value of the Company’s convertible notes was determined using current applicable rates for similar instruments with similar conversion and settlement features as of the balance sheet dates. The carrying value of the Company’s convertible notes payable approximated their fair value considering their short-term maturity dates and that the stated interest rate was near current market rates for instruments with similar conversion and settlement features. The fair value of the Company’s convertible notes and warrant liabilities were determined using “Level 3” inputs. Common Stock Warrants The Company classifies as equity any warrants that (i) require physical settlement or net-share net-cash net-share net-cash net-cash net-share Convertible Instruments The Company accounts for hybrid contracts that feature conversion options in accordance with applicable GAAP. Accounting Standards Codification 815 “Derivatives and Hedging Activities,” (“ASC 815”) requires companies to bifurcate conversion options from their host instruments and account for them as freestanding derivative financial instruments according to certain criteria. The criteria includes circumstances in which (a) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (b) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured Conversion options that contain variable settlement features such as provisions to adjust the conversion price upon subsequent issuances of equity or equity linked securities at exercise prices more favorable than that featured in the hybrid contract generally result in their bifurcation from the host instrument. The Company accounts for convertible instruments, when the Company has determined that the embedded conversion options should not be bifurcated from their host instruments, in accordance with ASC 470-20 470-20”). 470-20 The conversion features of the Notes Payable to Stockholders did not qualify as an embedded derivative instrument and bifurcated from the host convertible debentures was not necessary. Cash and Cash Equivalents Cash and cash equivalents are held in U.S. banks and consist of liquid investments and money market funds with a maturity from date of purchase of 90 days or less that are readily convertible into cash. Restricted Cash Restricted cash represents cash held in a depository account at a financial institution to collateralize a conditional stand-by non-current At December 31, 2017 and 2016 the Company had a $153 letter of credit as a security deposit on its leased office and laboratory facility that carries an automatic annual extension until February 21, 2021 at which time it will expire. The letter of credit is secured by a deposit in a money market account, as well as $51 deposited in a money market account as security for a credit card. Property and Equipment, net Property and equipment are recorded at cost less accumulated depreciation and amortization. Property and equipment are depreciated over their estimated useful lives using the straight-line method. Leasehold improvements are amortized over the shorter of the estimated remaining lease term or the useful lives of the related assets. Repairs and maintenance costs are expensed as incurred, whereas major improvements are capitalized as additions to property and equipment. Depreciation is provided over the following estimated useful lives: Asset Description Estimated Useful Lives Laboratory equipment 5 years Computer equipment 3 years Office furniture and equipment 5 years Leasehold improvements Shorter of estimated useful life or remaining lease term Upon retirement or sale, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is reflected in operations. Deferred Rent Deferred rent, included within accrued expenses in the consolidated balance sheet, consists of the difference between cash payments and the recognition of rent expense on a straight-line basis for the facilities the Company occupies. The Company’s lease for its Lexington, Massachusetts, facility provides for a rent-free period as well as fixed increases in minimum annual rental payments. The total amount of rental payments due over the lease term is being charged to rent expense ratably over the life of the lease. Impairment of Long-Lived Assets The Company accounts for long-lived assets in accordance with ASC 360. Long-lived assets, other than goodwill, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset or group of assets may not be recoverable. Application of alternative assumptions, such as changes in estimate of future cash flows, could produce significantly different results. Because of the significance of the judgments and estimation processes, it is likely that materially different amounts could be recorded if we used different assumptions or if the underlying circumstances were to change. For long-lived assets used in operations, impairment losses are only recorded if the asset’s carrying amount is not recoverable through its undiscounted, probability-weighted future cash flows. The Company measures the impairment loss based on the difference between the carrying amount and estimated fair value. Other than impairment of in-process research & development (“IPR&D”), to date no such impairment have been recognized on long-lived assets other than goodwill (Note 3). Revenue Recognition The Company’s principal sources of revenue during the reporting period were income from fees for services and reimbursement of clinical study costs. In all instances, revenue is recognized only when the price is fixed or determinable, persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, and collectability of the resulting receivable is reasonably assured. Milestones Contingent consideration from research and development activities that is earned upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. At the inception of each arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive. This evaluation includes an assessment of whether: (a) the consideration is commensurate with either (1) the entity’s performance to achieve the milestone or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement . The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment. Service revenues The Company recognized upfront non-refundable non-contingent non-contingent Research and Development Costs Research and development costs are expensed as incurred and include: salaries, benefits, bonus, stock-based compensation, license fees, milestone payments due under license agreements, costs paid to third-party contractors to perform research, conduct clinical trials, and develop drug materials and delivery devices; and associated overhead and facilities costs. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors, clinical research organizations (“CROs”) and clinical manufacturing organizations (“CMOs”). Invoicing from third-party contractors for services performed can lag several months. We accrue the costs of services rendered in connection with third-party contractor activities based on our estimate of management fees, and costs associated with monitoring site and data management. Stock-Based Compensation The Company recognizes all employee share-based compensation as a cost in the consolidated financial statements. Equity-classified awards principally related to stock options and restricted stock units (“RSUs”) which are measured at the grant date fair value of the award. The Company determines grant date fair value of stock option awards using the Black-Scholes option-pricing model. The fair value of restricted stock awards are determined using the closing price of the Company’s common stock on the grant date. For service based vesting grants, expense is recognized over the requisite service period based on the number of options or shares expected to ultimately vest. For performance based vesting grants, expense is recognized over the requisite period until the performance obligation is met, assuming that it is probable. No expense is recognized for performance based grants until it is probable the vesting criteria will be satisfied. Forfeitures are estimated at the date of grant and revised when actual or expected forfeiture activity differs materially from original estimates. Stock-based payments to non-employees re-measured Basic and Diluted Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share because common stock equivalents are excluded as their inclusion would be anti-dilutive. Income Taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. The Tax Cuts and Jobs Act (“the Act”) was enacted on December 22, 2017. The Act reduces the US federal corporate tax rate from 34% to 21%, requires companies to pay a one-time At December 31, 2017, the Company has completed its accounting for the tax effects of enactment of the Act, including the effects on its existing deferred tax balances and the one-time Goodwill Goodwill represents the difference between the consideration transferred and the fair value of the net assets acquired and liabilities assumed under the acquisition method of accounting for push-down accounting. Goodwill is not amortized but is evaluated for impairment within the Company’s single reporting unit on an annual basis, during the fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of the Company’s reporting unit below its carrying amount. The Company initially performs a qualitative assessment of goodwill which considers macro-economic conditions, industry and market trends, and the current and projected financial performance of the reporting unit. No further analysis is required if it is determined that there is a less than 50 percent likelihood that the carrying value is greater than the fair value. The Company completed a qualitative assessment and determined that there was no impairment of goodwill as of December 31, 2017. In-process In-process Annually, or more frequently if events or circumstances indicate that the asset may be impaired, the Company is required to prepare an impairment assessment on IPR&D. When performing the impairment assessment, the Company first assesses qualitative factors to determine whether it is necessary to recalculate the fair value of its acquired IPR&D. If the Company believes, as a result of the qualitative assessment, that it is more likely than not that the fair value of acquired IPR&D is less than its carrying amount, it calculates the asset’s fair value. If the carrying value of the Company’s acquired IPR&D exceeds its fair value, then the intangible asset is written down to its fair value.

Goodwill and IPR&D

Goodwill and IPR&D	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and IPR&D	3. Goodwill and IPR&D On June 15, 2015, the Company completed a merger with Pulmatrix Operating Company and recognized $15,943 of goodwill. The Company also recorded $7,534 of IPR&D and a related deferred tax liability of $2,959. As of December 31, 2017 and 2016, the Company impaired goodwill for $0 and $5,029, respectively. Goodwill has been assigned to the Company’s single reporting unit. As of December 31, 2016, the Company recorded a net impairment loss of $4,575 relating to the write-off

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Prepaid Expenses and Other Current Assets	4. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following: For the year ended December 31, 2017 2016 Prepaid Insurance $ 203 $ 197 Prepaid Clinical Trials 421 9 Prepaid Other 44 58 Accounts receivable 1 206 Deferred Operating Costs 27 107 $ 696 $ 577

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment consisted of the following: For the Year Ended December 31, 2017 2016 Laboratory equipment $ 2,476 $ 2,414 Computer equipment 216 254 Office furniture and equipment 214 214 Leasehold improvements 578 575 Total property and equipment 3,484 3,457 Less accumulated depreciation and amortization (2,870 ) (2,671 ) Property and equipment — net $ 614 $ 786 Depreciation and amortization expense for the years ended December 31, 2017 and 2016 was $246 and $250, respectively. During the years ended 2017 and 2016, the Company recorded gross fixed asset disposals of $47 and $350 and its related accumulated depreciation of $47 and $184, respectively.

Significant Agreements

Significant Agreements	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Significant Agreements	6. Significant Agreements License, Development and Commercialization Agreement On June 9, 2017, the Company entered into a License Agreement with RespiVert, a wholly owned subsidiary of Janssen Biotech, Inc., pursuant to which RespiVert granted the Company an exclusive, royalty-bearing license to its Licensed IP, to develop and commercialize products worldwide that incorporate the Licensed IP. The development, application, design and marketing of the Licensed IP for PUR1800 and PUR5700 and any licensed products will be managed exclusively by the Company. Under the terms of the License Agreement, the Company paid RespiVert an up-front, non-refundable The License Agreement terminates upon the expiration of the Company’s obligation to pay royalties for all licensed products, unless earlier terminated. In addition, the License Agreement may be terminated (i) by the Company for any reason upon 120 days’ advance notice to RespiVert; (ii) by RespiVert upon receipt of notice from the Company of either voluntary or involuntary insolvency proceedings of the Company; and (iii) by either party for a material breach which remains uncured following the applicable cure period. The Company recorded $1,000,000 in research and development expense for the upfront license fee during 2017. The next development milestone payment would be $1,000,000 and result from first dosing of a patient in a Phase IIb Clinical Trial for a licensed product. The payment will be made within 10 days of the first dosing of a patient in a Phase IIb Clinical Trial which is likely be in 2020. Feasibility and Development Agreement On September 5, 2017, the Company entered into a Feasibility and Development Agreement to develop Pulmatrix’s drug candidate, PUR0200, for chronic obstructive pulmonary disease (COPD) for the U.S. market with Vectura Limited (“Vectura”). Vectura and/or its partners will be responsible for all future development costs to advance the product for the U.S. Pulmatrix will provide the data package for PUR0200 and assist with the transfer of development and manufacturing activities to Vectura. As part of the agreement, a technology access fee of $1 million will be payable to Pulmatrix upon successful achievement of pre-agreed mid-teen Long-Acting Muscarinic Agent Collaboration Agreement On March 24, 2015, the Company entered into the long-acting muscarinic agent (“LAMA”) collaboration agreement (the “Mylan Agreement”) with Mylan. The focus of the Mylan Agreement is to continue the evaluation of the LAMA project (the “Product”) for the further development and manufacture as well as the commercialization and marketing of the Product by Mylan in territories outside the United States. Under the terms of the Mylan Agreement, the Company was eligible to receive reimbursement for third-party out of pocket expenses directly related to clinical trials. As consideration for the funding received, the Company agreed to grant to Mylan an option to negotiate for the exclusive right to develop, manufacture, commercialize and market any resulting products outside the United States for 180 days following the delivery of a clinical studies report, in exchange for a tiered share of gross profit of up to 20% of such pharmaceutical sales of the company. The Company recognized $835 of revenue under the Mylan Agreement during the year ended December 31, 2016. As of December 31, 2016, Mylan’s option expired and Pulmatrix owns the exclusive right to develop, manufacture, commercialize and market any resulting products of PUR0200.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	7. Debt Loan and Security Agreement and Warrant Agreement On June 11, 2015, Pulmatrix Operating entered into a Loan and Security Agreement (“LSA”) with Hercules Technology Growth Capital, Inc. (“Hercules”), for a term loan in a principal amount of $7,000 (the “Term Loan”). On June 15, 2015, following the completion of the Merger, the Company signed a joinder agreement with Hercules making it a co-borrower The Term Loan bears interest at a floating annual rate equal to the greater of (i) 9.50% and (ii) the sum of (a) the prime rate as reported by The Wall Street Journal minus 3.25% plus (b) 9.50%. The Company is required to make interest payments in cash on the first business day of each month, beginning on July 1, 2015. The Term Loan interest rate was 10.75% and 10.00% at December 31, 2017 and 2016, respectively. On August 1, 2016, the Company began making monthly payments on the first business day of each month consisting of principal and interest based upon a 30-month The Company may elect to prepay all, but not less than all, of the outstanding principal balance of the Term Loan, subject to a prepayment fee of 1% to 3%, depending on the date of repayment. Contingent on the occurrence of several events, including that the Company’s closing stock price exceed $11.73 per share for the seven days preceding a payment date, the Company may elect to pay, in whole or in part, any regularly scheduled installment of principal up to an aggregate maximum amount of $1,000 by converting a portion of the principal into shares of the Company’s common stock at a price of $11.73 per share. Hercules may elect to receive payments in the Company Common Stock by requiring the Company to affect a conversion option whereby Hercules can elect to receive a principal installment payment in shares of the Company Common Stock based on a price of $11.73 per share, subject to an aggregate maximum principal amount of $1,000. The Company determined that the Company’s provisions allowing conversion of all or a portion of the LSA contained a beneficial conversion feature (“BCF”). The BCF is contingent upon the occurrence of certain events and as such, the Company will not record the BCF until the contingency is resolved. Through December 31, 2017 the contingency was not resolved. The credit facility includes affirmative and negative covenants. The affirmative covenants include, among others, covenants requiring the Company to maintain its legal existence and governmental approvals, deliver certain financial reports and maintain insurance coverage. The negative covenants include, among others, restrictions on transferring collateral, incurring additional indebtedness, engaging in mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens, selling assets, and undergoing a change in control, in each case subject to certain exceptions. In general, the Term Loan prohibits the Company from (i) repurchasing or redeeming any class of capital stock, including common stock or (ii) declaring or paying any cash dividend or making cash distribution on any class of capital stock, including common stock. The Company complied with all covenants during the years ended December 31, 2017 and 2016. In connection with the making of the term loan the Company agreed that Hercules shall have the right to purchase up to $1,000 of securities, under terms and conditions equal to those afforded to other investors, in the event that the Company conducts a private placement for $10,000 or more of securities after the closing date. On June 16, 2015, in connection with the LSA, the Company granted to Hercules a warrant to purchase 25,150 shares of the Company’s common stock at an exercise price of $8.35 per share. The warrants are exercisable in whole or in part any time prior to the expiration date of June 16, 2020. At any point prior to the expiration of the warrants, Hercules may elect to convert all or a portion of the warrants into Company Common Stock on a net basis. In the event the warrants are not fully exercised and the fair market value of one share of Company Common Stock is greater than the exercise price of the warrant, upon the expiration date any outstanding warrants will be automatically exercised for shares of Company Common Stock on a net basis. The LSA includes provisions requiring the embedded interest rate reset upon an event of default and the put option upon an event of default or qualified change of control each represent an embedded derivative instrument requiring bifurcation from the loan. The embedded derivatives were bundled and valued as one compound derivative in accordance with the applicable accounting guidance for derivatives and hedging. The fair value of the compound derivative at issuance of $11 was recorded as a derivative liability and as a discount to the debt. The derivative liability is remeasured at fair value at each reporting date, with changes in fair value being recorded as other income (expense) in the consolidated statements of operations (Note 12). At December 31, 2017, the fair value of the derivative liability was remeasured and valued at $1. The net debt discounts resulting from the embedded compound derivative and lender fees are being amortized as interest expense from the date of issuance through the maturity date using the effective interest method. The Company incurred interest expense of $643 during the year ended December 31, 2017, which includes accretion of debt discount of $101. Of the remaining $542 interest expense, $472 was payable in cash and $70 relates to the Hercules end of term fee. For the year ended December 31, 2017, the Company also accreted debt issuance costs of $12 recorded to general and administrative expenses in accompanying consolidated statement of operations. The Company incurred interest expense of $881 during the year ended December 31, 2016, which includes accretion of debt discount of $112. Of the remaining $769 interest expense, $669 was payable in cash and $100 relates to the Hercules end of term fee. For the year ended December 31, 2016, the Company also accreted debt issuance costs of $16 recorded to general and administrative expenses in accompanying consolidated statement of operations. The carrying amounts of the Company’s Notes as of December 31, 2017 and December 31, 2016 were as follows: Hercules Term Loan Debt Discount Issuance Costs Total Balance — December 31, 2016 $ 5,954 $ (136 ) $ (15 ) $ 5,803 Accretion of debt discount 101 101 Accretion of issuance costs 12 12 Principal payments (2,695 ) (2,695 ) Balance — December 31, 2017 $ 3,259 $ (35 ) $ (3 ) $ 3,221 The remaining principal balance of the term loan of $3,259 is due for payment on July 1, 2018.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	8. Accrued Expenses and Other Current Liabilities Accrued expenses consisted of the following: December 31, 2017 2016 Accrued vacation $ 57 $ 54 Accrued wages and incentive 1,113 796 Accrued clinical & consulting 568 202 Accrued legal & patent 61 51 End of term fee 225 155 Deferred rent 68 46 Accrued other expenses 70 13 Total accrued expenses $ 2,162 $ 1,317

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Common Stock	9. Common Stock Registered Direct Offering On January 27, 2017, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with certain investors for the sale by the Company of 2,000,000 shares (the “Shares”) of the Company’s common stock, par value $0.0001 per share, at a purchase price of $2.50 per share in a registered direct offering. The closing of the sale of the Shares under the Purchase Agreement occurred on February 2, 2017. On February 3, 2017, the Company entered into a Securities Purchase Agreement (the “Second Purchase Agreement”) with certain investors for the sale by the Company of 950,000 shares of the Company’s common stock, par value $0.0001 per share, at a purchase price of $3.50 per share in a registered direct offering. The closing of the sale of the Shares under the Second Purchase Agreement occurred on February 8, 2017. Net of commissions, fees and other issuance costs totaling $727, aggregate net proceeds of the two noted registered direct offerings were $7,598. The Shares were offered and sold by the Company pursuant to an effective shelf registration statement on Form S-3, No. 333-212546), At-the-Market On March 17, 2017, the Company entered into an At-The-Market at-the-market S-3, No. 333-212546), BTIG is entitled to compensation at a fixed commission rate of 3.0% of the gross proceeds from the sale of the Company’s common stock pursuant to the Sales Agreement. During 2017, the Company sold 3,103,360 shares of its common stock under the Sales Agreement at an average selling price of approximately $2.93 per share which resulted in gross proceeds of approximately $9,096 and net proceeds of approximately $8,712 after payment of 3% commission to BTIG and other issuance costs.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Warrants	10. Warrants During the years ended December 31, 2017 and 2016, no warrants were issued by the Company. The following represents a summary of the warrants outstanding at each of the dates identified: Number of Shares Underlying Warrants For the Year Ended December 31, Issue Date Classification Exercise Price Expiration Date 2017 2016 June 15, 2015 Equity $ 7.55 June 15, 2020 3,190,030 3,190,030 June 15, 2015 Equity $ 8.35 June 16, 2020 25,150 25,150 August 31, 2015 Equity $ 11.80 August 31, 2020 30,000 30,000 March 21, 2014 Equity $ 22.66 March 21, 2019 37,100 37,100 March 21, 2014 Equity $ 22.66 March 21, 2019 2,160 2,160 All warrants are exercisable for common stock. At December 31, 2017, the intrinsic value of the common stock warrants outstanding was $0.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation The Company sponsors the Pulmatrix, Inc. 2013 Employee, Director and Consultant Equity Incentive Plan (the “2013 Plan”). As of December 31, 2017, the 2013 Plan provides for the grant of up to 4,193,075 shares of the Company’s common stock, of which 453,554 shares remained available for future grant. In addition, the Company sponsors two legacy plans under which no additional awards may be granted. As of December 31, 2017, the two legacy plans have a total of 499,271 options outstanding all of which are fully vested and for which common stock will be delivered upon exercise. Options During the year ended December 31, 2017, the Company granted options to purchase 1,054,555 shares of the Company’s common stock to employees, options to purchase 30,800 shares of the Company’s common stock to directors, and options to purchase 10,000 shares of the Company’s common stock to advisors. The stock options granted vest over time (the “Time Based Options”). Time Based Options vest over either 24 or 48 months. Subject to the grantee’s continuous service with the Company, Time Based Options vest in one of the following ways: (i) 50% at the one year anniversary of the Vesting Start Date and the remainder in 12 equal monthly installments beginning in the thirteenth month after the Vesting Start Date) or (ii) 25% at the one year anniversary of the Vesting Start Date and the remainder in 36 equal monthly installments beginning in the thirteenth month after the Vesting Start Date. Stock options generally expire ten years after the date of grant. The following table summarizes stock option activity for the year ended December 31, 2017: Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding — January 1, 2017 2,829,301 $ 6.89 7.85 $ — Granted 1,095,355 $ 2.34 Exercised (138,425 ) $ 2.19 Forfeited or expired (90,597 ) $ 8.04 Outstanding — December 31, 2017 3,695,634 $ 5.69 7.77 $ — Exercisable — December 31, 2017 1,803,612 $ 7.21 6.73 $ — Vested and expected to vest — December 31, 2017 3,646,249 $ 5.69 7.76 $ — The estimated fair values of employee stock options granted during the year ended December 31, 2017 and 2016, were determined on the date of grant using the Black-Scholes option-pricing model with the following assumptions: For the year ended December 31, 2017 2016 Expected option life (years) 6.12 6.22 Risk-free interest rate 1.89% – 2.25% 1.26% – 2.12% Expected volatility 74.0% – 86.3% 70.0% – 76.0% Expected dividend yield 0% 0% The risk-free interest rate was obtained from U.S. Treasury rates for the applicable periods. The Company’s expected volatility was based upon the historical volatility for industry peers and used an average of those volatilities. The expected life of the Company’s options was determined using the simplified method as a result of limited historical data regarding the Company’s activity. The forfeiture rate is calculated for non-performance As of December 31, 2017, there was $4,407 of unrecognized stock-based compensation expense related to unvested stock options granted under the Company’s stock award plans. This expense is expected to be recognized over a weighted-average period of approximately 2.0 years. Restricted Stock Units In June 2015, the Company granted some former officers 329,052 restricted stock units (the “RSUs”) of which 130,435 RSUs were immediately vested upon the date of the grant, 99,309 RSUs vested during the six months ended December 31, 2015 and the remaining 99,308 RSUs vested during the first six months in 2016. The shares of common stock underlying the RSUs were deliverable one year after the applicable vesting date of the respective RSU. In August 2015, the Company granted 10,374 RSUs to other employees that vest over a two-year The following table summarizes RSU activity for the year ended December 31, 2017: Number of Units Weighted- Average Grant Date Fair Value Total Grant Date Fair Value Outstanding — January 1, 2017 5,187 $ 5.50 $ 29 Granted — Vested (5,187 ) 5.50 (29 ) Forfeited or expired — — — Outstanding — December 31, 2017 — $ — $ — The following table presents total stock-based compensation expense for the years ended December 31, 2017 and 2016, respectively: For the years ended December 31, 2017 2016 Research and development $ 710 $ 763 General and administrative 2,095 3,235 Total stock based compensation expense $ 2,805 $ 3,998

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	12. Fair Value Measurements Information about the liabilities measured at fair value on a recurring basis as December 31, 2017 and December 31, 2016, and the input categories associated with those liabilities, is as follows: December 31, 2017 Fair Value Measurements Using Level 1 Level 2 Level 3 Total Liabilities: Embedded compound derivative $ — $ — $ 1 $ 1 December 31, 2016 Fair Value Measurements Using Level 1 Level 2 Level 3 Total Liabilities: Embedded compound derivative $ — $ — $ 35 $ 35 Goodwill As of December 31, 2016, the Company determined that it was more than a 50 percent likelihood that the carrying value of the goodwill was greater than the fair value. As such, the Company performed a two-step At December 31, 2017, based on a qualitative assessment, the Company determined that there was no more than a 50 percent likelihood that the carrying value of the goodwill was greater than the fair value as such impairment of goodwill was not considered necessary. The inputs used are generally unobservable and are therefore considered at level 3 hierarchy. These level 3 inputs were used to measure fair value of carrying value of assets and liabilities of the Company. A roll-forward of Goodwill is as follows: Goodwill Balance — January 1, 2016 $ 15,943 Impairment (5,029 ) Balance — December 31, 2016 10,914 Impairment — Balance — December 31, 2017 $ 10,914 Embedded Compound Derivatives — LSA with Hercules As described in Note 7, the LSA contains an interest rate reset upon an event of default and a put option upon an event of default or qualified change of control. Each of these features represents an embedded derivative instrument requiring bifurcation from the Term Loan. The embedded derivatives were bundled and valued as one compound derivative in accordance with the applicable accounting guidance for derivatives and hedging. The proceeds from the issuance of the Term Loan were allocated first to the warrant and compound derivative at their respective fair values, with the residual going to the carrying amount of the loan resulting in a discount to the face value of the debt. The fair value of the compound derivative upon issuance of $11 was recognized as a derivative liability and will be adjusted to fair value at each reporting date. The fair value of the derivative instruments is based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The Company used an income approach to estimate the fair value of the derivative liability and estimated the probability of an event of default occurring at various dates and then estimates the present value of the amount the holders would receive upon an event of default. The significant assumption used in the model is the probability of the following scenarios occurring: At Issuance Date At December 31, 2017 Probability of an event of default 10% 5% Prepayment penalties 1.0% – 3.0% 1.0% End of term payment $245,000 $245,000 Risk-free interest rate 1.01% 1.53% A roll-forward of the derivative liability categorized with Level 3 inputs is as follows: Derivative Instruments Balance — January 1, 2016 $ 11 Change in fair value 24 Balance — December 31, 2016 35 Change in fair value (34 ) Balance — December 31, 2017 $ 1 Gains and/or losses arising from changes in the estimated fair value of the warrants and embedded compound derivatives were recorded within other income, net, on the consolidated statement of operations.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company had no income tax expense due to operating losses incurred for the year ended December 31, 2017. The Company recorded a deferred income tax benefit for the year ended December 31, 2016 of $2,959 relating to a book impairment of a deferred tax liability set up in purchase accounting which was not subject to a valuation allowance. The components of the (benefit) provision for income taxes are as follows: Year Ended December 31, 2017 2016 Current income tax provision Federal $ — $ — State — — Total current income tax provision — — Deferred income tax (benefit) provision Federal — (2,356 ) State — (603 ) Total deferred income tax (benefit) provision — (2.959 ) Total income tax (benefit) provision $ — $ (2.959 ) A reconciliation of the provision for income taxes computed at the statutory federal income tax rate to the provision for income taxes as reflected in the financial statements is as follows: 2017 2016 Income tax computed at federal statutory tax rate 34.0 % 34.0 % State taxes, net of federal benefit 5.0 % 4.3 % Research and development credits 0.9 % 0.7 % Nondeductible interest (0.1 )% (0.1 )% Write-down of intangible asset 0.0 % (5.6 )% Permanent differences (0.3 )% (0.5 )% Federal deferred rate change (97.7 %) 0.0 % Other (3.1 )% (3.0 )% Change in valuation allowance 61.3 % (20.2 )% Total 0.0 % 9.6 % The significant components of the Company’s deferred tax assets as of December 31, 2017 and 2016 were as follows: 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 32,820 $ 43,455 Research and development credit carryforwards 2,789 2,493 Capitalized start-up 983 1,221 Other 2,377 2,862 Total deferred tax assets 38,969 50,031 Valuation allowance (38,969 ) (50,031 ) Net deferred tax liabilities $ — $ — At December 31, 2017, the Company had net operating loss carryforwards for federal and state income tax purposes of approximately $131,774 and $81,449 respectively, which were available to reduce future taxable income. The net operating loss carryforwards expire at various dates from 2023 through 2037. The Company has research and development credits for federal and state income tax purposes of approximately $1,925 and $1,094, respectively, which expire at various dates from 2022 through 2037. On December 22, 2017, the Tax Cuts and Jobs Act (“the Act”) was enacted in the United States. The Act reduces the U.S. federal corporate tax rate from 34% to 21%, requires companies to pay a one-time one-time As a result of the Act, the Company remeasured certain deferred tax assets and liabilities based on the rates at which they are anticipated to reverse in the future, which is generally 21%. This resulted in a decrease to the Company’s gross deferred tax assets and a corresponding decrease in its valuation allowance. Management of the Company evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets and determined that it is more likely than not that the Company will not recognize the benefits of the deferred tax assets. As a result, a full valuation allowance was recorded as of December 31, 2017 and 2016. The valuation allowance decreased by $11,062 during the year ended December 31, 2017, primarily due to impact of the decrease in the federal tax rate on the Company’s deferred tax assets, offset by current period losses incurred by the Company. The Company applies FASB Interpretation Number 48, “Accounting for Uncertainty in Income Taxes, an interpretation of FAS 109” (codified within ASC 740, Income Taxes), for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns. Unrecognized tax benefits represent tax positions for which reserves have been established. A full valuation allowance has been provided against the Company’s deferred tax assets, so that the effect of the unrecognized tax benefits is to reduce the gross amount of the deferred tax asset and the corresponding valuation allowance. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years. The Company files income tax returns in the United States for federal and state income taxes. In the normal course of business, the Company is subject to examination by tax authorities in the United States. Since the Company is in a loss carry-forward position, the Company is generally subject to U.S. federal and state income tax examinations by tax authorities for all years for which a loss carry-forward is utilized. The Company’s returns remain subject to federal and state audits for the years 2014 through 2017. However, carryforward attributes from prior years may still be adjusted upon examination by tax authorities if they are used in an open period. The Company may from time to time be assessed interest or penalties by major tax jurisdictions. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. The Company has not recorded interest or penalties on any unrecognized tax benefits since its inception. The Company anticipates that the amount of unrecognized tax benefits recorded will not materially change in the next twelve months. The roll-forward of the Company’s gross uncertain tax positions is as follows: Gross Uncertain Tax Position Balance — January 1, 2016 $ 1,086 Additions for current year tax positions 86 Balance — December 31, 2016 1,172 Additions for current year tax positions 59 Reductions for prior year tax positions (122 ) Balance — December 31, 2017 $ 1,109

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	14. Net Loss Per Share The following potentially dilutive securities outstanding prior to the use of the treasury stock method have been excluded from the computation of diluted weighted-average shares outstanding, as they would be anti-dilutive. As of December 31, 2017 2016 Options to purchase common stock 3,695,634 2,829,301 Warrants to purchase common stock 3,284,440 3,284,440 Settlement of Term Loan 85,251 85,251 Restricted Stock Units — 5,187 Total 7,065,325 6,204,179

Commitments

Commitments	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments	15. Commitments On October 27, 2015, the Company amended its operating lease for office and lab space to extend the termination date of the lease from December 2016 to December 2020, among other things. The amended lease provides for base rent, and the Company is responsible for real estate taxes, maintenance, and other operating expenses applicable to the leased premises. The amended lease agreement provides for an increasing monthly payment over the lease term. Future minimum lease payments under non-cancelable Amount 2018 654 2019 676 2020 698 Total $ 2,028 The Company has contracted with contract research organizations and contract manufacturing organizations to further the development of its most advanced assets. As of December 31, 2017, the outstanding obligation on these contracts totaled $2.8 million.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events During January and February 2018, the Company closed on the sale of 1,232,662 shares of common stock, at an average price of $1.54 per share, as part of an at-the-market Pursuant to the evergreen provision under the Pulmatrix, Inc. 2013 Employee, Director and Consultant Equity Incentive Plan, 903,600 shares were added to the total number of authorized shares under the plan.

Significant Accounting Polici23

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements represent the consolidation of the accounts of the Company and its subsidiary in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”). All intercompany accounts and transactions have been eliminated in consolidation.
Recent Accounting Standards	Recent Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) 2014-09”). 2014-09 605-35, Revenue Recognition - Construction-Type and Production-Type Contracts 2014-09 2014-09 2014-09 2014-09 2014-09 2014-09 2014-09 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date 2014-09 2015-14 In January 2017, the Financial Accounting Standard Board (the “FASB”) issued Accounting Standards Update (ASU) 2017-04: “Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment” 2017-04”), In May 2017, the Financial Accounting Standard Board (the “FASB”) issued Accounting Standards Update (ASU) 2017-09: Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting In July 2017, FASB issued ASU No. 2017-11, 2017-11 470-20, re-characterize
Segment Information	Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.
Use of Estimates	Use of Estimates In preparing consolidated financial statements in conformity with U.S. GAAP, management is required 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, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results may differ from these estimates. On an ongoing basis, the Company evaluates its estimates and assumptions. These estimates and assumptions include valuing equity securities in share-based payments, estimating fair value of equity instruments recorded as derivative liabilities, estimating the useful lives of depreciable and amortizable assets, valuation allowance against deferred tax assets, goodwill impairment, and estimating the fair value of long-lived assets to assess whether impairment charges may apply.
Concentrations of Credit Risk	Concentrations of Credit Risk Cash is a financial instrument that potentially subjects the Company to concentrations of credit risk. For all periods presented, substantially all of the Company’s cash was deposited in an account at a single financial institution that management believes is creditworthy. The Company is exposed to credit risk in the event of default by these financial institutions for amounts in excess of the Federal Deposit Insurance Corporation insured limits. The Company maintains its cash at a high quality financial institution and has not incurred any losses to date.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Valuations based on quoted prices for similar assets or liabilities in markets that are not active, or for which all significant inputs are observable, either directly or indirectly. Level 3 — Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The fair value of the Company’s convertible notes was determined using current applicable rates for similar instruments with similar conversion and settlement features as of the balance sheet dates. The carrying value of the Company’s convertible notes payable approximated their fair value considering their short-term maturity dates and that the stated interest rate was near current market rates for instruments with similar conversion and settlement features. The fair value of the Company’s convertible notes and warrant liabilities were determined using “Level 3” inputs.
Common Stock Warrants	Common Stock Warrants The Company classifies as equity any warrants that (i) require physical settlement or net-share net-cash net-share net-cash net-cash net-share
Convertible Instruments	Convertible Instruments The Company accounts for hybrid contracts that feature conversion options in accordance with applicable GAAP. Accounting Standards Codification 815 “Derivatives and Hedging Activities,” (“ASC 815”) requires companies to bifurcate conversion options from their host instruments and account for them as freestanding derivative financial instruments according to certain criteria. The criteria includes circumstances in which (a) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (b) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured Conversion options that contain variable settlement features such as provisions to adjust the conversion price upon subsequent issuances of equity or equity linked securities at exercise prices more favorable than that featured in the hybrid contract generally result in their bifurcation from the host instrument. The Company accounts for convertible instruments, when the Company has determined that the embedded conversion options should not be bifurcated from their host instruments, in accordance with ASC 470-20 470-20”). 470-20 The conversion features of the Notes Payable to Stockholders did not qualify as an embedded derivative instrument and bifurcated from the host convertible debentures was not necessary.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents are held in U.S. banks and consist of liquid investments and money market funds with a maturity from date of purchase of 90 days or less that are readily convertible into cash.
Restricted Cash	Restricted Cash Restricted cash represents cash held in a depository account at a financial institution to collateralize a conditional stand-by non-current At December 31, 2017 and 2016 the Company had a $153 letter of credit as a security deposit on its leased office and laboratory facility that carries an automatic annual extension until February 21, 2021 at which time it will expire. The letter of credit is secured by a deposit in a money market account, as well as $51 deposited in a money market account as security for a credit card.
Property and Equipment, net	Property and Equipment, net Property and equipment are recorded at cost less accumulated depreciation and amortization. Property and equipment are depreciated over their estimated useful lives using the straight-line method. Leasehold improvements are amortized over the shorter of the estimated remaining lease term or the useful lives of the related assets. Repairs and maintenance costs are expensed as incurred, whereas major improvements are capitalized as additions to property and equipment. Depreciation is provided over the following estimated useful lives: Asset Description Estimated Useful Lives Laboratory equipment 5 years Computer equipment 3 years Office furniture and equipment 5 years Leasehold improvements Shorter of estimated useful life or remaining lease term Upon retirement or sale, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is reflected in operations.
Deferred Rent	Deferred Rent Deferred rent, included within accrued expenses in the consolidated balance sheet, consists of the difference between cash payments and the recognition of rent expense on a straight-line basis for the facilities the Company occupies. The Company’s lease for its Lexington, Massachusetts, facility provides for a rent-free period as well as fixed increases in minimum annual rental payments. The total amount of rental payments due over the lease term is being charged to rent expense ratably over the life of the lease.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company accounts for long-lived assets in accordance with ASC 360. Long-lived assets, other than goodwill, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset or group of assets may not be recoverable. Application of alternative assumptions, such as changes in estimate of future cash flows, could produce significantly different results. Because of the significance of the judgments and estimation processes, it is likely that materially different amounts could be recorded if we used different assumptions or if the underlying circumstances were to change. For long-lived assets used in operations, impairment losses are only recorded if the asset’s carrying amount is not recoverable through its undiscounted, probability-weighted future cash flows. The Company measures the impairment loss based on the difference between the carrying amount and estimated fair value. Other than impairment of in-process research & development (“IPR&D”), to date no such impairment have been recognized on long-lived assets other than goodwill (Note 3).
Revenue Recognition	Revenue Recognition The Company’s principal sources of revenue during the reporting period were income from fees for services and reimbursement of clinical study costs. In all instances, revenue is recognized only when the price is fixed or determinable, persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, and collectability of the resulting receivable is reasonably assured. Milestones Contingent consideration from research and development activities that is earned upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. At the inception of each arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive. This evaluation includes an assessment of whether: (a) the consideration is commensurate with either (1) the entity’s performance to achieve the milestone or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement . The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
Service revenues	Service revenues The Company recognized upfront non-refundable non-contingent non-contingent
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred and include: salaries, benefits, bonus, stock-based compensation, license fees, milestone payments due under license agreements, costs paid to third-party contractors to perform research, conduct clinical trials, and develop drug materials and delivery devices; and associated overhead and facilities costs. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors, clinical research organizations (“CROs”) and clinical manufacturing organizations (“CMOs”). Invoicing from third-party contractors for services performed can lag several months. We accrue the costs of services rendered in connection with third-party contractor activities based on our estimate of management fees, and costs associated with monitoring site and data management.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes all employee share-based compensation as a cost in the consolidated financial statements. Equity-classified awards principally related to stock options and restricted stock units (“RSUs”) which are measured at the grant date fair value of the award. The Company determines grant date fair value of stock option awards using the Black-Scholes option-pricing model. The fair value of restricted stock awards are determined using the closing price of the Company’s common stock on the grant date. For service based vesting grants, expense is recognized over the requisite service period based on the number of options or shares expected to ultimately vest. For performance based vesting grants, expense is recognized over the requisite period until the performance obligation is met, assuming that it is probable. No expense is recognized for performance based grants until it is probable the vesting criteria will be satisfied. Forfeitures are estimated at the date of grant and revised when actual or expected forfeiture activity differs materially from original estimates. Stock-based payments to non-employees re-measured
Basic and Diluted Net Loss Per Share	Basic and Diluted Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share because common stock equivalents are excluded as their inclusion would be anti-dilutive.
Income Taxes	Income Taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. The Tax Cuts and Jobs Act (“the Act”) was enacted on December 22, 2017. The Act reduces the US federal corporate tax rate from 34% to 21%, requires companies to pay a one-time At December 31, 2017, the Company has completed its accounting for the tax effects of enactment of the Act, including the effects on its existing deferred tax balances and the one-time
Goodwill	Goodwill Goodwill represents the difference between the consideration transferred and the fair value of the net assets acquired and liabilities assumed under the acquisition method of accounting for push-down accounting. Goodwill is not amortized but is evaluated for impairment within the Company’s single reporting unit on an annual basis, during the fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of the Company’s reporting unit below its carrying amount. The Company initially performs a qualitative assessment of goodwill which considers macro-economic conditions, industry and market trends, and the current and projected financial performance of the reporting unit. No further analysis is required if it is determined that there is a less than 50 percent likelihood that the carrying value is greater than the fair value. The Company completed a qualitative assessment and determined that there was no impairment of goodwill as of December 31, 2017.
In-process Research & Development	In-process In-process Annually, or more frequently if events or circumstances indicate that the asset may be impaired, the Company is required to prepare an impairment assessment on IPR&D. When performing the impairment assessment, the Company first assesses qualitative factors to determine whether it is necessary to recalculate the fair value of its acquired IPR&D. If the Company believes, as a result of the qualitative assessment, that it is more likely than not that the fair value of acquired IPR&D is less than its carrying amount, it calculates the asset’s fair value. If the carrying value of the Company’s acquired IPR&D exceeds its fair value, then the intangible asset is written down to its fair value.
Accounting for Uncertainty in Income Taxes	The Company applies FASB Interpretation Number 48, “Accounting for Uncertainty in Income Taxes, an interpretation of FAS 109” (codified within ASC 740, Income Taxes), for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns. Unrecognized tax benefits represent tax positions for which reserves have been established. A full valuation allowance has been provided against the Company’s deferred tax assets, so that the effect of the unrecognized tax benefits is to reduce the gross amount of the deferred tax asset and the corresponding valuation allowance. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years. The Company files income tax returns in the United States for federal and state income taxes. In the normal course of business, the Company is subject to examination by tax authorities in the United States. Since the Company is in a loss carry-forward position, the Company is generally subject to U.S. federal and state income tax examinations by tax authorities for all years for which a loss carry-forward is utilized. The Company’s returns remain subject to federal and state audits for the years 2014 through 2017. However, carryforward attributes from prior years may still be adjusted upon examination by tax authorities if they are used in an open period. The Company may from time to time be assessed interest or penalties by major tax jurisdictions. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. The Company has not recorded interest or penalties on any unrecognized tax benefits since its inception. The Company anticipates that the amount of unrecognized tax benefits recorded will not materially change in the next twelve months. The roll-forward of the Company’s gross uncertain tax positions is as follows: Gross Uncertain Tax Position Balance — January 1, 2016 $ 1,086 Additions for current year tax positions 86 Balance — December 31, 2016 1,172 Additions for current year tax positions 59 Reductions for prior year tax positions (122 ) Balance — December 31, 2017 $ 1,109

Significant Accounting Polici24

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Property and Equipment Estimated Useful Lives	Depreciation is provided over the following estimated useful lives: Asset Description Estimated Useful Lives Laboratory equipment 5 years Computer equipment 3 years Office furniture and equipment 5 years Leasehold improvements Shorter of estimated useful life or remaining lease term

Prepaid Expenses and Other Cu25

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: For the year ended December 31, 2017 2016 Prepaid Insurance $ 203 $ 197 Prepaid Clinical Trials 421 9 Prepaid Other 44 58 Accounts receivable 1 206 Deferred Operating Costs 27 107 $ 696 $ 577

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following: For the Year Ended December 31, 2017 2016 Laboratory equipment $ 2,476 $ 2,414 Computer equipment 216 254 Office furniture and equipment 214 214 Leasehold improvements 578 575 Total property and equipment 3,484 3,457 Less accumulated depreciation and amortization (2,870 ) (2,671 ) Property and equipment — net $ 614 $ 786

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Summary of Carrying Amount of Company's Notes	The carrying amounts of the Company’s Notes as of December 31, 2017 and December 31, 2016 were as follows: Hercules Term Loan Debt Discount Issuance Costs Total Balance — December 31, 2016 $ 5,954 $ (136 ) $ (15 ) $ 5,803 Accretion of debt discount 101 101 Accretion of issuance costs 12 12 Principal payments (2,695 ) (2,695 ) Balance — December 31, 2017 $ 3,259 $ (35 ) $ (3 ) $ 3,221

Accrued Expenses and Other Cu28

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: December 31, 2017 2016 Accrued vacation $ 57 $ 54 Accrued wages and incentive 1,113 796 Accrued clinical & consulting 568 202 Accrued legal & patent 61 51 End of term fee 225 155 Deferred rent 68 46 Accrued other expenses 70 13 Total accrued expenses $ 2,162 $ 1,317

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of the Warrants Outstanding	The following represents a summary of the warrants outstanding at each of the dates identified: Number of Shares Underlying Warrants For the Year Ended December 31, Issue Date Classification Exercise Price Expiration Date 2017 2016 June 15, 2015 Equity $ 7.55 June 15, 2020 3,190,030 3,190,030 June 15, 2015 Equity $ 8.35 June 16, 2020 25,150 25,150 August 31, 2015 Equity $ 11.80 August 31, 2020 30,000 30,000 March 21, 2014 Equity $ 22.66 March 21, 2019 37,100 37,100 March 21, 2014 Equity $ 22.66 March 21, 2019 2,160 2,160

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity for the year ended December 31, 2017: Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding — January 1, 2017 2,829,301 $ 6.89 7.85 $ — Granted 1,095,355 $ 2.34 Exercised (138,425 ) $ 2.19 Forfeited or expired (90,597 ) $ 8.04 Outstanding — December 31, 2017 3,695,634 $ 5.69 7.77 $ — Exercisable — December 31, 2017 1,803,612 $ 7.21 6.73 $ — Vested and expected to vest — December 31, 2017 3,646,249 $ 5.69 7.76 $ —
Calculation of Fair Value Assumptions Using Black Scholes Option Model	The estimated fair values of employee stock options granted during the year ended December 31, 2017 and 2016, were determined on the date of grant using the Black-Scholes option-pricing model with the following assumptions: For the year ended December 31, 2017 2016 Expected option life (years) 6.12 6.22 Risk-free interest rate 1.89% – 2.25% 1.26% – 2.12% Expected volatility 74.0% – 86.3% 70.0% – 76.0% Expected dividend yield 0% 0%
Summary of Restricted Stock Unit Activity	The following table summarizes RSU activity for the year ended December 31, 2017: Number of Units Weighted- Average Grant Date Fair Value Total Grant Date Fair Value Outstanding — January 1, 2017 5,187 $ 5.50 $ 29 Granted — Vested (5,187 ) 5.50 (29 ) Forfeited or expired — — — Outstanding — December 31, 2017 — $ — $ —
Stock-Based Compensation Expense	The following table presents total stock-based compensation expense for the years ended December 31, 2017 and 2016, respectively: For the years ended December 31, 2017 2016 Research and development $ 710 $ 763 General and administrative 2,095 3,235 Total stock based compensation expense $ 2,805 $ 3,998

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Liabilities Measured at Fair Value on a Recurring Basis	Information about the liabilities measured at fair value on a recurring basis as December 31, 2017 and December 31, 2016, and the input categories associated with those liabilities, is as follows: December 31, 2017 Fair Value Measurements Using Level 1 Level 2 Level 3 Total Liabilities: Embedded compound derivative $ — $ — $ 1 $ 1 December 31, 2016 Fair Value Measurements Using Level 1 Level 2 Level 3 Total Liabilities: Embedded compound derivative $ — $ — $ 35 $ 35
Schedule of Goodwill	A roll-forward of Goodwill is as follows: Goodwill Balance — January 1, 2016 $ 15,943 Impairment (5,029 ) Balance — December 31, 2016 10,914 Impairment — Balance — December 31, 2017 $ 10,914
Schedule of Significant Assumption Used In Model Is Probability	The significant assumption used in the model is the probability of the following scenarios occurring: At Issuance Date At December 31, 2017 Probability of an event of default 10% 5% Prepayment penalties 1.0% – 3.0% 1.0% End of term payment $245,000 $245,000 Risk-free interest rate 1.01% 1.53%
Schedule of Derivative Liability Categorized with Level 3	A roll-forward of the derivative liability categorized with Level 3 inputs is as follows: Derivative Instruments Balance — January 1, 2016 $ 11 Change in fair value 24 Balance — December 31, 2016 35 Change in fair value (34 ) Balance — December 31, 2017 $ 1

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Components of (Benefit) Provision for Income Taxes	The components of the (benefit) provision for income taxes are as follows: Year Ended December 31, 2017 2016 Current income tax provision Federal $ — $ — State — — Total current income tax provision — — Deferred income tax (benefit) provision Federal — (2,356 ) State — (603 ) Total deferred income tax (benefit) provision — (2.959 ) Total income tax (benefit) provision $ — $ (2.959 )
Summary of Reconciliation of Expected Income Tax Benefit Computed Using Federal Statutory Income Tax Rate To Company's Effective Income Tax Rate	A reconciliation of the provision for income taxes computed at the statutory federal income tax rate to the provision for income taxes as reflected in the financial statements is as follows: 2017 2016 Income tax computed at federal statutory tax rate 34.0 % 34.0 % State taxes, net of federal benefit 5.0 % 4.3 % Research and development credits 0.9 % 0.7 % Nondeductible interest (0.1 )% (0.1 )% Write-down of intangible asset 0.0 % (5.6 )% Permanent differences (0.3 )% (0.5 )% Federal deferred rate change (97.7 %) 0.0 % Other (3.1 )% (3.0 )% Change in valuation allowance 61.3 % (20.2 )% Total 0.0 % 9.6 %
Summary of Components of Deferred Tax Assets	The significant components of the Company’s deferred tax assets as of December 31, 2017 and 2016 were as follows: 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 32,820 $ 43,455 Research and development credit carryforwards 2,789 2,493 Capitalized start-up 983 1,221 Other 2,377 2,862 Total deferred tax assets 38,969 50,031 Valuation allowance (38,969 ) (50,031 ) Net deferred tax liabilities $ — $ —
Summary of Roll-forward of Gross Uncertain Tax Positions	The roll-forward of the Company’s gross uncertain tax positions is as follows: Gross Uncertain Tax Position Balance — January 1, 2016 $ 1,086 Additions for current year tax positions 86 Balance — December 31, 2016 1,172 Additions for current year tax positions 59 Reductions for prior year tax positions (122 ) Balance — December 31, 2017 $ 1,109

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Computation of Diluted Weighted-Average Shares Outstanding Anti-Dilutive	The following potentially dilutive securities outstanding prior to the use of the treasury stock method have been excluded from the computation of diluted weighted-average shares outstanding, as they would be anti-dilutive. As of December 31, 2017 2016 Options to purchase common stock 3,695,634 2,829,301 Warrants to purchase common stock 3,284,440 3,284,440 Settlement of Term Loan 85,251 85,251 Restricted Stock Units — 5,187 Total 7,065,325 6,204,179

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments under the Non-Cancelable Operating Lease for Office and Lab Space	Future minimum lease payments under non-cancelable Amount 2018 654 2019 676 2020 698 Total $ 2,028

Organization - Additional Infor

Organization - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Organization And Basis Of Presentation [Line Items]
Accumulated deficit	$ (174,002)	$ (155,946)
Unrestricted Cash	3,600
Working capital deficit	1,600
At the Market Offering [Member] | BTIG LLC [Member]
Organization And Basis Of Presentation [Line Items]
Proceeds from sale of common stock	$ 8,712

Significant Accounting Polici36

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)
Summary of Significant Accounting Policies [Line Items]
Number of operating segment | Segment		1
Cash restricted for letter of credit		$ 153,000	$ 153,000
Money market account as security		$ 51,000
US federal corporate tax rate		34.00%	34.00%
Transition tax recognized		$ 0
Impairment of goodwill		$ 0	$ 5,029,000
Scenario Forecast [Member]
Summary of Significant Accounting Policies [Line Items]
US federal corporate tax rate	21.00%

Significant Accounting Polici37

Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2017
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	Shorter of estimated useful life or remaining lease term

Goodwill IPR&D - Additional Inf

Goodwill IPR&D - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 15, 2015USD ($)
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 10,914	$ 10,914	$ 15,943
Impairment of goodwill	$ 0	5,029
Number of reporting units | Segment	1
Net impairment loss relating to write-off of IPR&D and related deferred tax liability		$ 4,575
Pulmatrix Operating [Member]
Indefinite-lived Intangible Assets [Line Items]
Goodwill				$ 15,943
In-process research and development				7,534
Deferred tax liability				$ 2,959

Prepaid Expenses and Other Cu39

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Insurance	$ 203	$ 197
Prepaid Clinical Trials	421	9
Prepaid Other	44	58
Accounts receivable	1	206
Deferred Operating Costs	27	107
Total prepaid and other current assets	$ 696	$ 577

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 3,484	$ 3,457
Less accumulated depreciation and amortization	(2,870)	(2,671)
Property and equipment - net	614	786
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	2,476	2,414
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	216	254
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	214	214
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 578	$ 575

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property And Equipment [Abstract]
Depreciation and amortization expense	$ 246	$ 250
Gross fixed asset disposals	47	350
Gross fixed asset disposals, accumulated depreciation	$ 47	$ 184

Significant Agreements - Additi

Significant Agreements - Additional Information (Detail) - USD ($)	Jun. 09, 2017	Dec. 31, 2020	Dec. 31, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Research and development expense			$ 10,243,000	$ 10,152,000
Technology access fee			1,000,000
Revenue recognized during period			$ 335,000	835,000
License Agreement [Member]
Other Commitments [Line Items]
License fee	$ 1,000,000,000
License agreement termination description			The License Agreement may be terminated (i) by the Company for any reason upon 120 days’ advance notice to RespiVert; (ii) by RespiVert upon receipt of notice from the Company of either voluntary or involuntary insolvency proceedings of the Company; and (iii) by either party for a material breach which remains uncured following the applicable cure period.
License agreement termination notice period			120 days
Research and development expense			$ 1,000,000,000
License Agreement [Member] | Maximum [Member]
Other Commitments [Line Items]
Range of royalties based on sales, percentage	10.00%
License Agreement [Member] | Minimum [Member]
Other Commitments [Line Items]
Range of royalties based on sales, percentage	6.00%
License Agreement [Member] | Scenario Forecast [Member]
Other Commitments [Line Items]
Development milestone payment		$ 1,000,000,000
Development milestone payment period		10 days
Development and Commercial Milestones [Member] | License Agreement [Member] | Maximum [Member]
Other Commitments [Line Items]
Milestones payments	$ 1,000,000,000
Development and Commercial Milestones [Member] | License Agreement [Member] | Minimum [Member]
Other Commitments [Line Items]
Milestones payments	$ 80,000,000,000
Long-Acting Muscarinic Agent Collaboration Agreement [Member]
Other Commitments [Line Items]
Share percentage in gross profit			20.00%
Revenue recognized during period				$ 835,000

Debt - Loan and Security Agreem

Debt - Loan and Security Agreement and Warrant Agreement - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)d$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)	Jun. 16, 2015$ / sharesshares	Jun. 11, 2015USD ($)
Debt Instrument [Line Items]
Accrued end of term fee	$ 225,000	$ 155,000
Number of shares available for purchase of common stock in warrants | shares	0	0
Fair value of warrant derivative liabilities at issuance, recorded as debt discount	$ 1,000		$ 11,000
Remaining interest expense	643,000	$ 881,000
Term Loan [Member]
Debt Instrument [Line Items]
Total future principal payments	$ 3,259,000
Debt instrument, maturity date	Jul. 1, 2018
Hercules Loan and Security Agreement [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Term loan principal amount					$ 7,000,000
Debt instrument basis spread	9.50%
Interest rate during the period	10.75%	10.00%
Basis of debt instrument interest rate	The prime rate as reported by The Wall Street Journal minus 3.25% plus (b) 9.50%.
Debt instrument payment terms	The Company is required to make interest payments in cash on the first business day of each month, beginning on July 1, 2015.On August 1, 2016, the Company began making monthly payments on the first business day of each month consisting of principal and interest based upon a 30-month amortization schedule
Debt instrument periodic payment frequency	30-month amortization schedule
Repayment charges	$ 245,000
Accrued end of term fee	$ 225,000
Percentage of prepayment fee	1.00%
Percentage of prepayment fee	3.00%
Maximum principal amount available for conversion into common shares	$ 1,000,000
Debt instrument, convertible, stock price trigger | $ / shares	$ 11.73
Debt instrument, convertible, threshold trading days | d	7
Number of shares available for purchase of common stock in warrants | shares				25,150
Common stock exercise price | $ / shares				$ 8.35
Warrants expiration date	Jun. 16, 2020
Interest expense	$ 643,000	$ 881,000
Interest expense payable in cash	472,000	669,000
Remaining interest expense	542,000	769,000
End of term fee	70,000	100,000
Accretion of debt discount	101,000	112,000
Debt issuance costs	$ 12,000	$ 16,000
Hercules Loan and Security Agreement [Member] | Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Floating annual rate	9.50%
Hercules Loan and Security Agreement [Member] | Term Loan [Member] | Minimum [Member] | Private Placement [Member]
Debt Instrument [Line Items]
Repurchase of securities	$ 10,000,000
Hercules Loan and Security Agreement [Member] | Term Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Repurchase of securities	$ 1,000,000
Hercules Loan and Security Agreement [Member] | Term Loan [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Debt instrument basis spread	3.25%

Debt - Summary of Carrying Amou

Debt - Summary of Carrying Amount of Company's Notes (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Short And Long Term Debt [Line Items]
Beginning balance	$ (136)
Accretion of debt discount	101
Accretion of issuance costs, debt discount	0
Ending balance	(35)
Beginning balance	(15)
Accretion of issuance costs, issuance costs	12
Ending balance	(3)
Beginning balance	5,803
Accretion of debt discount	101
Accretion of issuance costs	12
Principal payments	(2,695)
Ending balance	3,221
Hercules Term Loan [Member]
Short And Long Term Debt [Line Items]
Beginning balance	5,954
Accretion of issuance costs	0
Principal payments	(2,695)
Ending balance	$ 3,259

Accrued Expenses and Other Cu45

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued vacation	$ 57	$ 54
Accrued wages and incentive	1,113	796
Accrued clinical & consulting	568	202
Accrued legal & patent	61	51
End of term fee	225	155
Deferred rent	68	46
Accrued other expenses	70	13
Total accrued expenses	$ 2,162	$ 1,317

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - USD ($)	Feb. 03, 2017	Jan. 27, 2017	Dec. 31, 2017	Mar. 17, 2017	Dec. 31, 2016
Temporary Equity [Line Items]
Common stock, par value			$ 0.0001		$ 0.0001
At the Market Offering [Member] | BTIG LLC [Member]
Temporary Equity [Line Items]
Sale of stock, number of shares sold in transaction			3,103,360
Proceeds from sale of common stock			$ 8,712,000
Fixed commission rate entitled to placement agent			3.00%
Average selling price of common stock			$ 2.93
Gross proceeds from sale of shares			$ 9,096,000
At the Market Offering [Member] | BTIG LLC [Member] | Maximum [Member]
Temporary Equity [Line Items]
Aggregate offering on sale of common stock				$ 11,000,000
Registered Direct Offering [Member]
Temporary Equity [Line Items]
Payment of commissions and other issuance cost			727,000
Proceeds from sale of common stock			$ 7,598,000
Registered Direct Offering [Member] | Securities Purchase Agreement [Member]
Temporary Equity [Line Items]
Sale of stock, number of shares sold in transaction	950,000	2,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Sale of stock, price per share	$ 3.50	$ 2.50

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Warrants and Rights Note Disclosure [Abstract]
Number of warrants issued	0	0
Intrinsic value of the common stock warrants outstanding	$ 0

Warrants - Summary of the Warra

Warrants - Summary of the Warrants Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Class of Warrant or Right [Line Items]
Warrants Outstanding	0	0
Private Placement Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Issue Date	Jun. 15, 2015
Warrants, Classification	Equity
Warrants, Exercise Price	$ 7.55
Warrants, Expiration Date	Jun. 15, 2020
Warrants Outstanding	3,190,030	3,190,030
Hercules Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Issue Date	Jun. 15, 2015
Warrants, Classification	Equity
Warrants, Exercise Price	$ 8.35
Warrants, Expiration Date	Jun. 16, 2020
Warrants Outstanding	25,150	25,150
MTS Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Issue Date	Aug. 31, 2015
Warrants, Classification	Equity
Warrants, Exercise Price	$ 11.80
Warrants, Expiration Date	Aug. 31, 2020
Warrants Outstanding	30,000	30,000
Representative's Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Issue Date	Mar. 21, 2014
Warrants, Classification	Equity
Warrants, Exercise Price	$ 22.66
Warrants, Expiration Date	Mar. 21, 2019
Warrants Outstanding	37,100	37,100
Underwriter's Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Issue Date	Mar. 21, 2014
Warrants, Classification	Equity
Warrants, Exercise Price	$ 22.66
Warrants, Expiration Date	Mar. 21, 2019
Warrants Outstanding	2,160	2,160

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) $ in Thousands	1 Months Ended		6 Months Ended		12 Months Ended
	Aug. 31, 2015shares	Jun. 30, 2015shares	Jun. 30, 2016shares	Dec. 31, 2015shares	Dec. 31, 2017USD ($)Installmentshares	Dec. 31, 2016USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding					3,695,634	2,829,301
Number of options to purchase common stock, Granted					1,095,355
Unrecognized stock-based compensation expenses | $					$ 4,407
Unrecognized stock-based compensation expense, period for recognition					2 years
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period					10 years
Employee Stock Option [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options to purchase common stock, Granted					1,054,555
Employee Stock Option [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options to purchase common stock, Granted					30,800
Employee Stock Option [Member] | Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options to purchase common stock, Granted					10,000
Employee Stock Option [Member] | Time Based Options Vesting 24 Month [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period					24 months
Award vesting percentage					50.00%
Number of equal vesting installments | Installment					12
Award vesting term					50% at the one year anniversary of the Vesting Start Date and the remainder in 12 equal monthly installments beginning in the thirteenth month after the Vesting Start Date
Employee Stock Option [Member] | Time Based Options Vesting 48 Month [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period					48 months
Award vesting percentage					25.00%
Number of equal vesting installments | Installment					36
Award vesting term					25% at the one year anniversary of the Vesting Start Date and the remainder in 36 equal monthly installments beginning in the thirteenth month after the Vesting Start Date
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, granted					0
Restricted stock units, options vested					5,187
Stock-based compensation | $					$ 13	$ 1,171
Restricted Stock Units [Member] | Former Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, granted		329,052
Restricted stock units, options vested		130,435	99,308	99,309
Restricted Stock Units [Member] | Other Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Restricted stock units, granted	10,374
2013 Employee, Director and Consultant Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate shares of Common Stock that may be delivered under options outstanding					4,193,075
Shares available for future grant					453,554
Legacy Share Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate shares of Common Stock that may be delivered under options outstanding					0
Shares outstanding					499,271

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Outstanding beginning balance	2,829,301
Number of options, Granted	1,095,355
Number of options, Exercised	(138,425)
Number of options, Forfeited or expired	(90,597)
Number of options, Outstanding ending balance	3,695,634	2,829,301
Number of options, Exercisable	1,803,612
Number of options, Vested and expected to vest	3,646,249
Weighted average exercise price, Outstanding beginning balance	$ 6.89
Weighted average exercise price, Granted	2.34
Weighted average exercise price, Exercised	2.19
Weighted average exercise price, Forfeited or expired	8.04
Weighted average exercise price, Outstanding ending balance	5.69	$ 6.89
Weighted average exercise price, Exercisable	7.21
Weighted average exercise price, Vested and expected to vest	$ 5.69
Weighted average remaining contractual term, Outstanding ending balance	7 years 9 months 7 days	7 years 10 months 6 days
Weighted average remaining contractual term, Exercisable	6 years 8 months 23 days
Weighted average remaining contractual term, Vested and expected to vest	7 years 9 months 3 days
Aggregate intrinsic value, Outstanding	$ 0
Aggregate intrinsic value, Exercised	$ 0
Aggregate intrinsic value, Forfeited or expired	$ 0
Aggregate intrinsic value, Outstanding	$ 0
Aggregate intrinsic value, Exercisable	0
Aggregate intrinsic value, Vested and expected to vest	$ 0

Stock-Based Compensation - Esti

Stock-Based Compensation - Estimated Fair Values of Employee Stock Options Granted (Detail) - Employee Stock Option [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life (years)	6 years 1 month 13 days	6 years 2 months 19 days
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.89%	1.26%
Expected volatility	74.00%	70.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.25%	2.12%
Expected volatility	86.30%	76.00%

Stock-Based Compensation - Su52

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units, Beginning balance | shares	5,187
Number of units, Granted | shares	0
Number of units, Vested | shares	(5,187)
Number of units, Forfeited or expired | shares	0
Weighted average grant date fair value, Outstanding beginning balance | $ / shares	$ 5.50
Weighted average grant date fair value, Granted | $ / shares	0
Weighted average grant date fair value, Vested | $ / shares	5.50
Weighted average grant date fair value, Forfeited or expired | $ / shares	$ 0
Total grant date fair value, Outstanding, Beginning balance | $	$ 29
Total grant date fair value, Granted | $	0
Total grant date fair value, Vested | $	(29)
Total grant date fair value, Forfeited or expired | $	$ 0

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 2,805	$ 3,998
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	710	763
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 2,095	$ 3,235

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Liabilities Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Embedded Compound Derivative [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Derivative liability		$ 35
Preferred Stock Warrants [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Derivative liability	$ 1
Level 3 [Member] | Embedded Compound Derivative [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Derivative liability	11	$ 35
Level 3 [Member] | Preferred Stock Warrants [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Derivative liability	$ 1

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets Liabilities Quantitative Information [Line Items]
Impairment of goodwill	$ 0	$ 5,029
Fair Value, Measurements, Recurring [Member] | Embedded Compound Derivative [Member]
Fair Value Assets Liabilities Quantitative Information [Line Items]
Derivative liability		35
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Embedded Compound Derivative [Member]
Fair Value Assets Liabilities Quantitative Information [Line Items]
Derivative liability	$ 11	$ 35

Fair Value Measurements - Sch56

Fair Value Measurements - Schedule of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance	$ 10,914	$ 15,943
Impairment	0	(5,029)
Ending Balance	$ 10,914	$ 10,914

Fair Value Measurements - Sch57

Fair Value Measurements - Schedule of Significant Assumption Used in Model is Probability (Detail) - Fair Value, Measurements, Recurring [Member] - Level 3 [Member] - Embedded Compound Derivative [Member] - USD ($) $ in Thousands	Jun. 11, 2015	Dec. 31, 2017
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability of an event of default	10.00%	5.00%
Prepayment penalties		1.00%
End of term payment	$ 245,000	$ 245,000
Risk-free interest rate	1.01%	1.53%
Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment penalties	1.00%
Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment penalties	3.00%

Fair Value Measurements - Sch58

Fair Value Measurements - Schedule of Derivative Liability Categorized with Level 3 (Detail) - Derivative Instruments [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 35	$ 11
Change in fair value	(34)	24
Ending balance	$ 1	$ 35

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred income tax benefit			$ (2,959,000)
Net operating loss carryforwards for federal income tax purposes		$ 131,774,000
Net operating loss carryforwards for state income tax purposes		$ 81,449,000
Net operating loss carryforwards, expiration date description		Various dates from 2023 through 2037.
Research and development credit		$ 2,789,000	$ 2,493,000
Research and development credit, expiration date description		Various dates from 2022 through 2037.
U.S. federal corporate tax rate		34.00%	34.00%
Transition tax		$ 0
Decrease in deferred tax assets valuation allowance		(11,062,000)
Scenario Forecast [Member]
Operating Loss Carryforwards [Line Items]
U.S. federal corporate tax rate	21.00%
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Research and development credit		1,925,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Research and development credit		$ 1,094,000

Income Taxes - Components of (B

Income Taxes - Components of (Benefit) Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Current income tax provision
Federal	$ 0	$ 0
State	0	0
Total current income tax provision	$ 0	0
Deferred income tax (benefit) provision
Federal		(2,356)
State		(603)
Total deferred income tax (benefit) provision		(2,959)
Total income tax (benefit) provision		$ (2,959)

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Expected Income Tax Benefit Computed Using Federal Statutory Income Tax Rate To Company's Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax computed at federal statutory tax rate	34.00%	34.00%
State taxes, net of federal benefit	5.00%	4.30%
Research and development credits	0.90%	0.70%
Nondeductible interest	(0.10%)	(0.10%)
Write-down of intangible asset	(0.00%)	(5.60%)
Permanent differences	(0.30%)	(0.50%)
Federal deferred rate change	(97.70%)	0.00%
Other	(3.10%)	(3.00%)
Change in valuation allowance	61.30%	(20.20%)
Total	0.00%	9.60%

Income Taxes - Summary of Compo

Income Taxes - Summary of Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 32,820	$ 43,455
Research and development credit carryforwards	2,789	2,493
Capitalized start-up expenses	983	1,221
Other	2,377	2,862
Total deferred tax assets	38,969	50,031
Valuation allowance	(38,969)	(50,031)
Net deferred tax liabilities	$ 0	$ 0

Income Taxes - Summary of Roll-

Income Taxes - Summary of Roll-forward of Gross Uncertain Tax Positions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 1,172	$ 1,086
Additions for current year tax positions	59	86
Reductions for prior year tax positions	(122)
Balance as of end of year	$ 1,109	$ 1,172

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Computation of Diluted Weighted-Average Shares Outstanding Anti-Dilutive (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	7,065,325	6,204,179
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share		5,187
Term Loan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	85,251	85,251
Warrants To Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	3,284,440	3,284,440
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	3,695,634	2,829,301

Commitments - Additional Inform

Commitments - Additional Information (Detail) - USD ($) $ in Millions	Oct. 27, 2015	Oct. 26, 2015	Dec. 31, 2017
Commitment And Contingencies [Line Items]
Lease termination date	Dec. 31, 2020	Dec. 31, 2016
Lease amendment date			Oct. 27, 2015
Material Transfer Agreement [Member]
Commitment And Contingencies [Line Items]
Outstanding obligation under the contract			$ 2.8

Commitments - Schedule of Futur

Commitments - Schedule of Future Minimum Lease Payments under the Non-Cancelable Operating Lease for Office and Lab Space (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 654
2,019	676
2,020	698
Total	$ 2,028

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	2 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 31, 2017
Subsequent Event [Member] | At-the-market Facility [Member]
Sale of stock, number of shares sold in transaction	1,232,662
Sale of stock, price per share	$ 1.54
Proceeds from sale of common stock	$ 1.8
2013 Employee, Director and Consultant Equity Incentive Plan [Member]
Total number of additional authorized shares under the plan		903,600