Immunic (IMUX) 10-Q 8 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	VITAL THERAPIES INC
Entity Central Index Key	1,280,776
Trading Symbol	VTL
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		42,368,998

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 43,647	$ 56,901
Prepaid expenses and other current assets	1,188	1,220
Total current assets	44,835	58,121
Property and equipment, net	2,072	2,155
Other assets	101	108
Total assets	47,008	60,384
Current liabilities:
Accounts payable	893	1,049
Accrued expenses	8,701	9,141
Other current liabilities	72	91
Total current liabilities	9,666	10,281
Long-term liabilities	47	59
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 20,000,000 authorized and no shares issued or outstanding at March 31, 2018 and December 31, 2017	0	0
Common stock, $0.0001 par value; 130,000,000 shares authorized at March 31, 2018 and December 31, 2017; 42,368,864 and 42,368,864 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	4	4
Additional paid-in capital	347,557	345,915
Accumulated other comprehensive income	75	78
Accumulated deficit	(310,341)	(295,953)
Total stockholders’ equity	37,295	50,044
Total liabilities and stockholders’ equity	$ 47,008	$ 60,384

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	130,000,000	130,000,000
Common stock, shares issued (in shares)	42,368,864	42,368,864
Common stock, shares outstanding (in shares)	42,368,864	42,368,864

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating expenses:
Research and development	$ 10,157	$ 9,628
General and administrative	4,335	3,059
Total operating expenses	14,492	12,687
Loss from operations	(14,492)	(12,687)
Other income (expense):
Interest income	170	97
Other income (expense), net	(66)	(12)
Total other income	104	85
Net loss	$ (14,388)	$ (12,602)
Net loss per share, basic and diluted (in USD per share)	$ (0.34)	$ (0.39)
Weighted-average common shares outstanding, basic and diluted (in shares)	42,368,864	32,645,103

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (14,388)	$ (12,602)
Other comprehensive income (loss):
Unrealized gain (loss) on cash equivalents	(3)	1
Total comprehensive loss	$ (14,391)	$ (12,601)

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (14,388)	$ (12,602)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	224	335
Stock-based compensation	1,553	1,263
Common stock issued for services	89	0
Other	(4)	(2)
Changes in operating assets and liabilities:
Other current assets and prepaid expenses	69	(316)
Accounts payable	(145)	396
Accrued expenses	(441)	33
Other liabilities	(31)	(17)
Net cash used in operating activities	(13,074)	(10,910)
Cash flows from investing activities:
Purchases of property and equipment	(150)	(274)
Proceeds from sale of equipment	0	3
Net cash used in investing activities	(150)	(271)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	0	37,825
Deferred financing costs	(30)	0
Proceeds from exercise of stock options	0	1
Net cash (used in) provided by financing activities	(30)	37,826
Net change in cash and cash equivalents	(13,254)	26,645
Cash and cash equivalents, beginning of period	56,901	59,991
Cash and cash equivalents, end of period	43,647	86,636
Supplemental disclosure of noncash investing and financing activities:
Stock issuance costs included in liabilities	0	481
Purchases of property and equipment included in liabilities	$ 7	$ 87

Description of Business and Bas

Description of Business and Basis of Financial Statements	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Description of Business and Basis of Financial Statements	Description of Business and Basis of Financial Statements Description of Business We are a clinical-stage biotechnology company focusing on the discovery, development and commercialization of cell-based therapies capable of transforming the management of life-threatening conditions. Our initial product candidate, the ELAD ® System, or ELAD, is a human-cell-based, bio-artificial liver which is being developed to improve rates of survival among patients with acute forms of liver failure. Since inception, we have devoted essentially all of our efforts to product development, clinical testing and pilot manufacturing and have not recognized revenues from our planned principal operations. In August 2015, we reported that our VTI-208 phase 3 clinical trial of ELAD in severe alcoholic hepatitis failed to reach its primary or secondary endpoints, although medically pertinent pre-specified subsets based on age and disease severity did show trends toward efficacy. Considering the results of the VTI-208 clinical trial and in an effort to focus our personnel and financial resources, we also discontinued our VTI-210 and VTI-212 clinical trials. In March 2018, we completed enrollment in our phase 3 clinical trial, VTL-308, of 151 subjects with severe alcoholic hepatitis. The trial design of VTL-308, was based on our analysis of the results of the VTI-208 clinical trial. Our business, operating results, financial condition and growth prospects are subject to significant risks and uncertainties including the failure of our clinical trial to meet its endpoint, failure to obtain regulatory approval to commercialize ELAD and failure to secure additional funding to complete the development and commercialization of ELAD. Liquidity We have a history of incurring losses and negative cash flows from operations and have an accumulated deficit of $310.3 million through March 31, 2018 . Assuming limited activities related to the submission for a biologics license application, or BLA, and that we do not begin building any significant commercial infrastructure, we believe that our existing cash and cash equivalents of $43.6 million as of March 31, 2018 should be sufficient to fund our operations through the first quarter of 2019, past the expected announcement of topline data for the VTL-308 clinical trial, which we currently anticipate to be in the third quarter of 2018, likely September. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect. The timing and amount of our actual expenditures will be based on many factors, including, but not limited to, the completion of our VTL-308 clinical trial, the timing of any possible submission of a BLA, decisions with respect to building commercial operations, and any unforeseen cash needs which may deplete current cash and cash equivalents sooner than planned. In any case, we will need additional liquidity to fund operations prior to a year from the date of the issuance of our condensed consolidated financial statements for the three months ended March 31, 2018. Our capital requirements and our ability to fund such requirements are expected to be different based on the outcome of the VTL-308 clinical trial. With successful clinical data, we plan to substantially increase our BLA and commercialization activities and, therefore, our costs. In this event, we would seek to obtain funding through equity or debt financing, and possibly marketing and distribution arrangements or other collaborations, strategic alliances or licensing agreements. Should the VTL-308 clinical trial require additional clinical development or should the trial be unsuccessful, we would attempt to substantially restructure our operations to conserve funds and possibly sell assets or even liquidate the company, depending on the VTL-308 data. In this event, we may also seek funding through similar sources; however, funding in such circumstances would be expected to be more difficult to secure, if at all. We currently have an effective shelf registration statement on Form S-3 on file with the SEC, which expires May 26, 2018. The shelf registration statement currently permits the offering, issuance and sale by us of up to an aggregate offering price of $112.5 million of common stock, preferred stock, warrants, debt securities or units in one or more offerings and in any combination, of which $62.2 million may be offered, issued and sold under an “at-the-market” sales agreement with Cantor Fitzgerald & Co. We expect to file for a new shelf registration statement around the expiration date of the existing Form S-3 registration statement. However, there is no assurance that we will be able to obtain additional funding on acceptable terms or at all. If we are not able to secure adequate additional funding, we will be required to make reductions in certain spending to extend current funds. If we are unable to raise adequate funds, we may have to liquidate some or all of our assets, or we may have to delay, reduce the scope of, or eliminate some or all of our development programs and further clinical development. We may also have to delay development or commercialization of our products or license to third parties the rights to commercialize products or technology that we would otherwise seek to commercialize. Any of these factors could harm our operating results and future prospects. Based on the above, substantial doubt exists over our ability to continue as a going concern for one year from the date of the issuance of our condensed consolidated financial statements for the three months ended March 31, 2018. Basis of Presentation and Consolidation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or GAAP, and the rules and regulations of the SEC related to a quarterly report on Form 10-Q. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The condensed consolidated balance sheet as of December 31, 2017 included in this report has been derived from the audited consolidated financial statements included in our Annual Report on Form 10-K. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments that are necessary for a fair statement of the financial position, results of operations and cash flows for the periods presented. All such adjustments are of a normal and recurring nature. In addition, our condensed consolidated financial statements have been prepared assuming that we will continue as a going concern, which contemplates the realization of asset and the settlement of liabilities and commitments in the normal course of business. The condensed consolidated financial statements for the three months ended March 31, 2018 do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that could result from uncertainty related to our ability to continue as a going concern. Unaudited Interim Financial Information The results for the three months ended March 31, 2018 are not necessarily indicative of results to be expected for the year ending December 31, 2018 or any other future interim period or year. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2017, included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission, or SEC, on March 13, 2018. The unaudited interim condensed consolidated financial statements include the accounts of Vital Therapies, Inc. and its wholly-owned subsidiaries located in the United Kingdom and China, both of which are currently inactive. All intercompany accounts and transactions have been eliminated in consolidation. We manage our operations as a single reportable segment for the purposes of assessing performance and making operating decisions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires us to make certain estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates and assumptions. Cash and Cash Equivalents Cash and cash equivalents consist of cash and highly-liquid investments with original maturities of three months or less when acquired. Cash equivalents are stated at cost unless they are securities, in which case they are recorded at fair value, which approximates original cost. Fair Value of Financial Instruments Fair value is defined as the price that would be received to sell an asset or be paid to transfer a liability in an orderly transaction between market participants on the measurement date. Accounting guidance establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Our Level 1 assets consisted of money market funds for the periods presented. We had no Level 1 liabilities for the periods presented. Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets with insufficient volume or infrequent transactions (less active markets), or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated with observable market data for substantially the full term of the assets or liabilities. We had no Level 2 assets or liabilities for the periods presented. Level 3—Unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of assets or liabilities. We had no Level 3 assets or liabilities for the periods presented. Any transfers into and out of levels within the fair value hierarchy will be recognized at the end of the reporting period in which the actual event or change in circumstances that caused the transfer occurs. The carrying value of cash and cash equivalents, other current assets and prepaid expenses, accounts payable, accrued expenses and other current liabilities approximates fair value due to the short period of time to maturity. Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the assets (generally three to five years). Leasehold improvements are stated at cost and depreciated on a straight-line basis over the lesser of the remaining term of the related lease or the estimated useful lives of the assets. Construction in progress is not depreciated until the underlying asset is available to be placed in service. Repairs and maintenance costs are charged to expense as incurred. Impairment of Long-Lived Assets Long-lived assets consist primarily of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. We have not recognized any impairment losses in either the three months ended March 31, 2018 or the year ended December 31, 2017 . Clinical Trial Accruals As part of the process of preparing our condensed consolidated financial statements, we are required to estimate our accrued expenses. Our clinical trial accrual process seeks to account for expenses resulting from our obligations under agreements with clinical sites, clinical research organizations, or CROs, vendors, and consultants in connection with conducting our clinical trials. We account for these expenses according to the progress of each trial as measured by subject enrollment, the timing of various aspects of the trial and if available, information from our service providers. During the course of a clinical trial, we adjust our rate of clinical expense recognition if actual results differ from our estimates. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary, and could result in us reporting amounts that may later be determined to be higher or lower than our estimates for a particular period and adjustments to our research and development expenses may be necessary in future periods. Research and Development Research and development costs consist primarily of employee-related expenses, costs of contractors, clinical trial sites and CROs engaged in the development of ELAD, costs related to our investigation of the mechanism of action of ELAD, expenses associated with obtaining regulatory approvals, and the cost of acquiring and manufacturing clinical trial materials. All research and development costs are expensed as incurred. Stock-Based Compensation We measure and recognize compensation expense for all stock-based compensation for employees and directors based on the estimated fair value at the date of grant, and to consultants based on the ongoing estimated fair value. Currently, our stock-based awards consist only of stock options; however, future grants under our equity compensation plan may also consist of shares of restricted stock, restricted stock units, stock appreciation rights, performance awards and performance units. We estimate the fair value of stock options using the Black-Scholes-Merton, or BSM, option pricing model, which requires the use of estimates. We recognize stock-based compensation cost for employees and directors for ratably vesting stock options on a straight-line basis over the requisite service period of the award. For performance-based stock options to employees and directors, we record stock-based compensation expense only when the performance-based milestone is deemed probable of achievement. We utilize both quantitative and qualitative criteria to judge whether milestones are probable of achievement. The fair value of options granted to consultants is estimated using the BSM option pricing model and is re-measured at each reporting date with changes in fair value prior to vesting recognized as expense in the condensed consolidated statements of operations across the applicable vesting period. For performance-based stock options held by consultants, we record stock-based compensation expense only when the performance-based milestone is achieved unless there is a performance commitment. The BSM option pricing model requires the input of highly-subjective assumptions, including the risk-free interest rate, the expected dividend yield of our common stock, the expected volatility of the price of our common stock, and the expected term of the option. These estimates involve inherent uncertainties and the application of management’s judgment. If factors change and different assumptions are used, our stock-based compensation expense could be materially different in the future. These assumptions are estimated as follows: Risk-free Interest Rate We base the risk-free interest rate assumption on zero-coupon U.S. treasury instruments appropriate for the expected term of the stock option grants. Expected Dividend Yield We base the expected dividend yield assumption on the fact that we have never paid cash dividends and have no present intention to pay cash dividends. Consequently, we used an expected dividend yield of zero . Expected Volatility The expected stock price volatility for our common stock is estimated based on volatilities of a peer group of similar publicly-traded, biotechnology companies by taking the average historic price volatility for the peers for a period equivalent to the expected term of the stock option grants. We do not use our average historical price volatility as we have only been a publicly-traded company since April 2014. Expected Term The expected term represents the period of time that options are expected to be outstanding. As we do not have sufficient historical experience for determining the expected term of the stock option awards granted, we have determined the expected life assumption for employee and director stock options using the comparable average expected term utilizing those companies in the peer group as noted above. For consultant stock options, we estimate the expected term based on the period we expect each consultant to provide services to us. Leases We lease all of our research, manufacturing and office space and enter into various other operating lease agreements in conducting our business. At the inception of each lease, we evaluate the lease agreement to determine whether the lease is an operating or capital lease. Some of our lease agreements may contain renewal options, tenant improvement allowances, rent holidays or rent escalation clauses. When such items are included in a lease agreement, we record a deferred rent asset or liability equal to the difference between the rent expense and future minimum lease payments due. The rent expense related to operating leases is recognized on a straight-line basis in the statements of operations over the term of each lease. In cases where our lessor grants us leasehold improvement allowances that reduce our rent expense, we capitalize the improvements as incurred and recognize deferred rent, which is amortized over the shorter of the lease term or the expected useful life of the improvements. Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Accumulated other comprehensive income has been reflected as a separate component of stockholders’ equity in the accompanying condensed consolidated balance sheets. Foreign Currency Translation and Transactions The functional currency of each of our subsidiaries in the United Kingdom and China, both of which are currently inactive, is the local currency. Assets and liabilities of the subsidiaries are translated at the rate of exchange at the balance sheet date. Expenses are translated at the average exchange rates in effect during the reporting period. Gains and losses resulting from foreign currency translation are included in accumulated other comprehensive income in the accompanying condensed consolidated balance sheets. Gains and losses resulting from foreign currency transactions are included in the condensed consolidated statements of operations, which to date have not been significant. Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the condensed consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. We recognize net deferred tax assets to the extent we believe these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that we would be able to realize our deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. As of March 31, 2018 and December 31, 2017 , we maintained a full valuation allowance against our entire balance of deferred tax assets. We record uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. We recognize interest and penalties related to unrecognized tax benefits, if any, within income tax expense, and any accrued interest and penalties are included within the related tax liability line. Net Loss Per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted-average number of common shares and, if dilutive, common stock equivalents outstanding for the period determined using the treasury-stock method. Common stock equivalents are comprised of options outstanding under our stock option plan and warrants for the purchase of common stock. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share attributable to common stockholders because to do so would be anti-dilutive are as follows: As of March 31, 2018 2017 Options to purchase common stock 7,740,808 4,863,702 Warrants to purchase common stock 240,620 240,620 Recently Issued and/or Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, "Leases," or ASU 2016-02. ASU 2016-02 will require that lease arrangements longer than 12 months result in an entity recognizing an asset and liability equal to the present value of the lease payments in the statement of financial position. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods therein. This standard requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. We expect to adopt ASU 2016-02 in 2019. The adoption of this guidance is expected to result in a significant increase in the total assets and liabilities reported on our consolidated balance sheets. In November 2016, the FASB issued ASU No. 2016-18, " Statement of Cash Flows: Restricted Cash ," or ASU 2016-18. ASU 2016-18 provides guidance on the classification of restricted cash in the statements of cash flows. This ASU requires that our statements of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. We adopted this standard in the first quarter of 2018, and the adoption did not have any impact on our condensed consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, “ Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting,” or ASU 2017-09. The amendments in this update provide guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under Topic 718. We adopted this standard in the first quarter of 2018, and the adoption did not have a significant impact on our condensed consolidated financial statements.

Other Financial Information

Other Financial Information	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Financial Information	Other Financial Information Property and Equipment Property and equipment, leasehold improvements, and related accumulated depreciation and amortization were as follows (in thousands): March 31, December 31, Manufacturing, clinical and laboratory equipment $ 7,616 $ 7,500 Leasehold improvements 4,727 4,727 Office furniture and equipment 246 234 Construction in progress 30 17 12,619 12,478 Less: accumulated depreciation and amortization (10,547 ) (10,323 ) Total $ 2,072 $ 2,155 Depreciation and amortization expense was $224,000 and $335,000 for the three months ended March 31, 2018 and 2017 , respectively. Accrued Expenses Accrued expenses consist of (in thousands): March 31, December 31, Accrued clinical and related costs $ 6,219 $ 5,377 Accrued compensation and related taxes 1,820 3,591 Accrued other 662 173 Total $ 8,701 $ 9,141

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases We lease office, manufacturing and research and development facilities and equipment under various non-cancellable operating lease agreements with expiration dates into 2022 . Our facility leases generally provide for periodic rent increases and many contain escalation clauses. In May 2017, we entered into a new lease, or the Lease, extending the term of our existing manufacturing and research and development facility lease from June 2017 to June 2022. The Lease includes a renewal option and requires the payment of our proportionate share of the facility’s operating expenses. We recognize rent expense for our facility operating leases on a straight-line basis. We account for the difference between the minimum lease payments and the straight-line amount as deferred rent. Total rent, property taxes and routine maintenance expense under our operating leases was $298,000 and $255,000 for the three months ended March 31, 2018 and 2017 , respectively. Current and long-term deferred rent totaled $72,000 and $47,000 at March 31, 2018 , and $91,000 and $59,000 at December 31, 2017 , respectively. Legal Proceedings We are not currently a party to any litigation, nor are we aware of any pending or threatened litigation against us, that we believe would materially affect our business, operating results, financial condition or cash flows. However, our industry is characterized by frequent claims and litigation including securities litigation, claims regarding patent and other intellectual property rights and claims for product liability. As a result, in the future, we may be involved in various legal proceedings from time to time.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	Fair Value The following fair value hierarchy tables present information about each major category of our financial assets and liabilities measured at fair value on a recurring basis (in thousands): Fair Value Measurement at March 31, 2018 Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ 42,639 $ 42,639 $ — $ — Fair Value Measurement at December 31, 2017 Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ 55,245 $ 55,245 $ — $ — There were no liabilities measured at fair value on a recurring basis as of March 31, 2018 or as of December 31, 2017 . The carrying amounts of other current assets and prepaid expenses, accounts payable, accrued expenses, and other current liabilities approximate their fair values due to their short-term nature. For our money market funds, unrealized gains and losses are reported as accumulated other comprehensive income (loss), and realized gains and losses are included in interest income on the condensed consolidated statements of operations. There were no transfers between Level 1, Level 2 or Level 3 for our assets during the periods presented.

Common Stock and Stock Warrants

Common Stock and Stock Warrants	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Common Stock and Stock Warrants	Common Stock and Stock Warrants Shelf Registration Statement We currently have an effective shelf registration statement on Form S-3 on file. The shelf registration statement permits: (i) the offering, issuance and sale by us of up to a maximum aggregate offering price of $200.0 million of common stock, preferred stock, warrants, debt securities, and/or units in one or more offerings and in any combination; (ii) sales of up to 2.5 million shares of common stock by certain selling stockholders; and (iii) the offering, issuance and sale by us of up to a maximum aggregate offering price of $75.0 million of our common stock that may be issued and sold under an “at-the-market” sales agreement, or ATM, with Cantor Fitzgerald & Co. Since filing the Form S-3 in May 2015, we have raised gross proceeds under the shelf registration statement of $74.7 million from two follow-on public offerings and $12.8 million pursuant to the ATM through December 31, 2017. We did not sell any shares under the shelf registration statement during the three months ended March 31, 2018 . At March 31, 2018 , $112.5 million remains available for issuance and sale under the shelf registration statement, $62.2 million of which may be offered, issued and sold under the ATM. The shelf registration statement on Form S-3 expires on May 26, 2018. Common Stock Issued for Services On October 30, 2017, we entered into an independent consulting agreement, or the Consulting Agreement, with two consulting groups, or the Consultants, pursuant to which we issued 60,000 restricted shares of our common stock to the Consultants as partial consideration for investor relations services to be rendered. The restricted shares have not been registered based on a specific exemption from the registration requirements of the Securities Act. The terms of the Consulting Agreement state that we have the right to terminate the Consulting Agreement at any time, upon providing written notice. We had the right to terminate this agreement for any reason within 180 days following the effective date, whereby each of the Consultants would have been required to promptly surrender to us 40% of the number of restricted shares issued to it. In connection with this transaction, we valued 36,000 shares, or 60% of the shares, at the quoted market price of $207,000 , or $5.75 , per share, on the date of the agreement. The remaining 24,000 shares are being adjusted to fair value based on the closing price at the end of the reporting period with the expense being recorded ratably over the 180 -day period. We recognized expense in connection with these consulting shares of $89,000 during the three months ended March 31, 2018 in general and administrative expenses. Stock Warrants We issued warrants in connection with financing activities and for consulting services prior to our initial public offering. As of March 31, 2018 , warrants for 240,620 shares of common stock were outstanding and exercisable at an exercise price of $92.99 and expire in September 2019. Stock Reserved for Future Issuance Shares reserved for future issuance at March 31, 2018 are as follows: Number of Shares Common stock options outstanding 7,740,808 Common stock options available for future grant: 2014 Equity Incentive Plan 56,506 2017 Inducement Equity Incentive Plan 261,168 Common stock warrants 240,620 Total common shares reserved for future issuance 8,299,102

Stock Compensation Plans

Stock Compensation Plans	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Compensation Plans	Stock Compensation Plans Equity Incentive Plans Our 2014 Equity Incentive Plan, or the 2014 Plan, became effective in April 2014 and replaced our 2012 Stock Option Plan, or the 2012 Plan, with respect to future awards. The 2014 Plan provides for the grant of stock options, restricted stock, restricted stock units, stock appreciation rights, performance awards and performance units to employees, directors and consultants. The 2012 Plan provided for the grant of stock options, restricted stock, restricted stock units, stock purchase rights and performance awards to employees, directors and consultants. Option grants under our 2012 Plan were exercisable immediately and subject to repurchase rights, all of which have lapsed. Shares available for grant under the 2014 Plan include any shares remaining available or becoming available in the future under the 2012 Plan due to cancellation or forfeiture. In addition, the 2014 Plan provides for annual increases in the number of shares available for issuance thereunder beginning upon its effective date in April 2014, and on each annual anniversary, equal to the lower of: • 1,200,000 shares of our common stock; • 3% of the outstanding shares of our common stock on the second-to-the-last day prior to each anniversary date of the effectiveness date of our initial public offering; or • an amount as our board of directors may determine. Shares available for grant under the 2014 Plan totaled 56,506 shares as of March 31, 2018 . In addition, pursuant to the above provisions, the number of shares available for issuance under the 2014 Plan was increased by 1,200,000 shares effective April 16, 2018. In September 2017, our board of directors approved the 2017 Inducement Equity Incentive Plan and amended and restated the plan in November 2017, or the Inducement Plan, which has terms and conditions substantially similar to our 2014 Plan. Under the Inducement Plan, 1,850,000 shares of our common stock were reserved to be used exclusively for non-qualified grants to individuals who were not previously our employees or directors, as an inducement material to the individual’s entry into employment with us within the meaning of Rule 5635(c)(4) of the Nasdaq Listing Rules. During the three months ended March 31, 2018 , we granted options to purchase 1,588,832 shares of our common stock under the Inducement Plan leaving 261,168 shares available for grant under this plan. Option grants made under the 2014 Plan and the 2012 Plan generally vest over one year or ratably over four years except for performance-based stock options. Our performance-based stock options will fully vest and become exercisable only on achievement of the performance conditions while the participant is a continuing service provider. Options currently outstanding under the Inducement Plan become 25% vested on the one year anniversary of the grant date and then vest ratably over an additional three years. Options generally expire ten years from the grant date or earlier in accordance with the terms of the plans and the related stock option agreement. In 2015, our board of directors (the “Board”) approved grants for performance-based stock options to certain employees and consultants under the 2014 Plan. Performance-based stock options for 651,140 shares remain outstanding at March 31, 2018 . Performance-based stock options that have not been forfeited will fully vest on the third anniversary of the grant date if (i) our VTL-308 clinical trial has achieved statistical significance in its primary efficacy endpoint and (ii) the participant is a continuing service provider through the third anniversary of the grant date (as such terms are defined in the 2014 Plan). Vesting of the performance-based stock options will not be accelerated if the performance goal is achieved in less than three years . As of March 31, 2018 and 2017 , we deemed the performance condition as being probable and are recording stock-based compensation expense over the requisite service period for all performance-based stock options held by employees. The performance-based stock options have exercise prices ranging from $4.57 to $7.69 per share, the closing sales price of our common stock on the grant dates, and expire ten years from the grant date (or earlier in accordance with the terms of the 2014 Plan and the related stock option agreement). The following table summarizes stock option activity under the 2012 Plan, 2014 Plan and the Inducement Plan: Options Weighted- Weighted- Aggregate Outstanding as of January 1, 2018 6,083,482 $ 6.76 Granted 1,669,104 $ 6.31 Exercised — $ — Forfeited or expired (11,778 ) $ 5.74 Outstanding as of March 31, 2018 7,740,808 $ 6.66 7.35 $ 9,639,492 Options vested and expected to vest as of March 31, 2018 7,579,288 $ 6.68 7.31 $ 9,434,249 Options exercisable as of March 31, 2018 3,704,451 $ 7.92 5.56 $ 3,152,405 Stock-Based Compensation Expense The weighted-average grant date fair value of stock options granted during the three months ended March 31, 2018 and 2017 was $4.40 and $3.48 , respectively. The following are the ranges of underlying assumptions used in the BSM option pricing model to determine the fair value of stock options granted to employees and to non-employees under all stock plans: Three Months Ended March 31, 2018 2017 Employees: Risk-free interest rate 2.0% - 2.1% 1.5% Expected dividend yield 0% 0% Expected volatility 79.8% - 82.0% 85.4% Expected term of options (years) 6.1 5.9 Fair value of common stock $6.30 - $6.45 $5.05 Non-employees: Risk-free interest rate 2.1% - 2.7% 1.0% - 1.9% Expected dividend yield 0% 0% Expected volatility 73.4% - 80.9% 75.6% - 83.3% Expected term of options (years) 0.4 - 9.3 1.3 - 4.5 Fair value of common stock $6.45 - $6.80 $4.00 Total stock-based compensation expense for all stock awards recognized in our condensed consolidated statements of operations is as follows (in thousands): Three Months 2018 2017 Employees: Research and development $ 389 $ 460 General and administrative 1,044 787 Total $ 1,433 $ 1,247 Non-employees: Research and development $ 51 $ 16 General and administrative 69 — Total $ 120 $ 16 As of March 31, 2018 , there was $11.4 million and $1.1 million of total compensation cost related to unvested employee and non-employee stock option awards, respectively, not yet recognized. The fair value of the non-employee stock options is re-measured at each reporting date and, accordingly, the expense to be recognized will change, primarily with changes in the market value of our common stock. Stock-based compensation expense for employee and non-employee stock option awards is expected to be recognized over a remaining weighted-average vesting period of 2.5 years and 1.8 years, respectively.

Summary of Significant Accoun14

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or GAAP, and the rules and regulations of the SEC related to a quarterly report on Form 10-Q. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The condensed consolidated balance sheet as of December 31, 2017 included in this report has been derived from the audited consolidated financial statements included in our Annual Report on Form 10-K. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments that are necessary for a fair statement of the financial position, results of operations and cash flows for the periods presented. All such adjustments are of a normal and recurring nature. In addition, our condensed consolidated financial statements have been prepared assuming that we will continue as a going concern, which contemplates the realization of asset and the settlement of liabilities and commitments in the normal course of business. The condensed consolidated financial statements for the three months ended March 31, 2018 do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that could result from uncertainty related to our ability to continue as a going concern. Unaudited Interim Financial Information The results for the three months ended March 31, 2018 are not necessarily indicative of results to be expected for the year ending December 31, 2018 or any other future interim period or year. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2017, included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission, or SEC, on March 13, 2018. The unaudited interim condensed consolidated financial statements include the accounts of Vital Therapies, Inc. and its wholly-owned subsidiaries located in the United Kingdom and China, both of which are currently inactive. All intercompany accounts and transactions have been eliminated in consolidation. We manage our operations as a single reportable segment for the purposes of assessing performance and making operating decisions.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires us to make certain estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates and assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash and highly-liquid investments with original maturities of three months or less when acquired. Cash equivalents are stated at cost unless they are securities, in which case they are recorded at fair value, which approximates original cost.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received to sell an asset or be paid to transfer a liability in an orderly transaction between market participants on the measurement date. Accounting guidance establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Our Level 1 assets consisted of money market funds for the periods presented. We had no Level 1 liabilities for the periods presented. Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets with insufficient volume or infrequent transactions (less active markets), or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated with observable market data for substantially the full term of the assets or liabilities. We had no Level 2 assets or liabilities for the periods presented. Level 3—Unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of assets or liabilities. We had no Level 3 assets or liabilities for the periods presented. Any transfers into and out of levels within the fair value hierarchy will be recognized at the end of the reporting period in which the actual event or change in circumstances that caused the transfer occurs. The carrying value of cash and cash equivalents, other current assets and prepaid expenses, accounts payable, accrued expenses and other current liabilities approximates fair value due to the short period of time to maturity.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the assets (generally three to five years). Leasehold improvements are stated at cost and depreciated on a straight-line basis over the lesser of the remaining term of the related lease or the estimated useful lives of the assets. Construction in progress is not depreciated until the underlying asset is available to be placed in service. Repairs and maintenance costs are charged to expense as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist primarily of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets.
Clinical Trial Accruals	Clinical Trial Accruals As part of the process of preparing our condensed consolidated financial statements, we are required to estimate our accrued expenses. Our clinical trial accrual process seeks to account for expenses resulting from our obligations under agreements with clinical sites, clinical research organizations, or CROs, vendors, and consultants in connection with conducting our clinical trials. We account for these expenses according to the progress of each trial as measured by subject enrollment, the timing of various aspects of the trial and if available, information from our service providers. During the course of a clinical trial, we adjust our rate of clinical expense recognition if actual results differ from our estimates. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary, and could result in us reporting amounts that may later be determined to be higher or lower than our estimates for a particular period and adjustments to our research and development expenses may be necessary in future periods.
Research and Development	Research and Development Research and development costs consist primarily of employee-related expenses, costs of contractors, clinical trial sites and CROs engaged in the development of ELAD, costs related to our investigation of the mechanism of action of ELAD, expenses associated with obtaining regulatory approvals, and the cost of acquiring and manufacturing clinical trial materials. All research and development costs are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation We measure and recognize compensation expense for all stock-based compensation for employees and directors based on the estimated fair value at the date of grant, and to consultants based on the ongoing estimated fair value. Currently, our stock-based awards consist only of stock options; however, future grants under our equity compensation plan may also consist of shares of restricted stock, restricted stock units, stock appreciation rights, performance awards and performance units. We estimate the fair value of stock options using the Black-Scholes-Merton, or BSM, option pricing model, which requires the use of estimates. We recognize stock-based compensation cost for employees and directors for ratably vesting stock options on a straight-line basis over the requisite service period of the award. For performance-based stock options to employees and directors, we record stock-based compensation expense only when the performance-based milestone is deemed probable of achievement. We utilize both quantitative and qualitative criteria to judge whether milestones are probable of achievement. The fair value of options granted to consultants is estimated using the BSM option pricing model and is re-measured at each reporting date with changes in fair value prior to vesting recognized as expense in the condensed consolidated statements of operations across the applicable vesting period. For performance-based stock options held by consultants, we record stock-based compensation expense only when the performance-based milestone is achieved unless there is a performance commitment. The BSM option pricing model requires the input of highly-subjective assumptions, including the risk-free interest rate, the expected dividend yield of our common stock, the expected volatility of the price of our common stock, and the expected term of the option. These estimates involve inherent uncertainties and the application of management’s judgment. If factors change and different assumptions are used, our stock-based compensation expense could be materially different in the future. These assumptions are estimated as follows: Risk-free Interest Rate We base the risk-free interest rate assumption on zero-coupon U.S. treasury instruments appropriate for the expected term of the stock option grants. Expected Dividend Yield We base the expected dividend yield assumption on the fact that we have never paid cash dividends and have no present intention to pay cash dividends. Consequently, we used an expected dividend yield of zero . Expected Volatility The expected stock price volatility for our common stock is estimated based on volatilities of a peer group of similar publicly-traded, biotechnology companies by taking the average historic price volatility for the peers for a period equivalent to the expected term of the stock option grants. We do not use our average historical price volatility as we have only been a publicly-traded company since April 2014. Expected Term The expected term represents the period of time that options are expected to be outstanding. As we do not have sufficient historical experience for determining the expected term of the stock option awards granted, we have determined the expected life assumption for employee and director stock options using the comparable average expected term utilizing those companies in the peer group as noted above. For consultant stock options, we estimate the expected term based on the period we expect each consultant to provide services to us.
Leases	Leases We lease all of our research, manufacturing and office space and enter into various other operating lease agreements in conducting our business. At the inception of each lease, we evaluate the lease agreement to determine whether the lease is an operating or capital lease. Some of our lease agreements may contain renewal options, tenant improvement allowances, rent holidays or rent escalation clauses. When such items are included in a lease agreement, we record a deferred rent asset or liability equal to the difference between the rent expense and future minimum lease payments due. The rent expense related to operating leases is recognized on a straight-line basis in the statements of operations over the term of each lease. In cases where our lessor grants us leasehold improvement allowances that reduce our rent expense, we capitalize the improvements as incurred and recognize deferred rent, which is amortized over the shorter of the lease term or the expected useful life of the improvements.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Accumulated other comprehensive income has been reflected as a separate component of stockholders’ equity in the accompanying condensed consolidated balance sheets.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions The functional currency of each of our subsidiaries in the United Kingdom and China, both of which are currently inactive, is the local currency. Assets and liabilities of the subsidiaries are translated at the rate of exchange at the balance sheet date. Expenses are translated at the average exchange rates in effect during the reporting period. Gains and losses resulting from foreign currency translation are included in accumulated other comprehensive income in the accompanying condensed consolidated balance sheets. Gains and losses resulting from foreign currency transactions are included in the condensed consolidated statements of operations, which to date have not been significant.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the condensed consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. We recognize net deferred tax assets to the extent we believe these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that we would be able to realize our deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. As of March 31, 2018 and December 31, 2017 , we maintained a full valuation allowance against our entire balance of deferred tax assets. We record uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. We recognize interest and penalties related to unrecognized tax benefits, if any, within income tax expense, and any accrued interest and penalties are included within the related tax liability line.
Net Loss Per Share	Net Loss Per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted-average number of common shares and, if dilutive, common stock equivalents outstanding for the period determined using the treasury-stock method. Common stock equivalents are comprised of options outstanding under our stock option plan and warrants for the purchase of common stock. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position.
Recently Issued and/or Adopted Accounting Standards	Recently Issued and/or Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, "Leases," or ASU 2016-02. ASU 2016-02 will require that lease arrangements longer than 12 months result in an entity recognizing an asset and liability equal to the present value of the lease payments in the statement of financial position. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods therein. This standard requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. We expect to adopt ASU 2016-02 in 2019. The adoption of this guidance is expected to result in a significant increase in the total assets and liabilities reported on our consolidated balance sheets. In November 2016, the FASB issued ASU No. 2016-18, " Statement of Cash Flows: Restricted Cash ," or ASU 2016-18. ASU 2016-18 provides guidance on the classification of restricted cash in the statements of cash flows. This ASU requires that our statements of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. We adopted this standard in the first quarter of 2018, and the adoption did not have any impact on our condensed consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, “ Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting,” or ASU 2017-09. The amendments in this update provide guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under Topic 718.

Summary of Significant Accoun15

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share	Potentially dilutive securities not included in the calculation of diluted net loss per share attributable to common stockholders because to do so would be anti-dilutive are as follows: As of March 31, 2018 2017 Options to purchase common stock 7,740,808 4,863,702 Warrants to purchase common stock 240,620 240,620

Other Financial Information (Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Property and Equipment, Leasehold Improvements, and Related Accumulated Depreciation and Amortization	Property and equipment, leasehold improvements, and related accumulated depreciation and amortization were as follows (in thousands): March 31, December 31, Manufacturing, clinical and laboratory equipment $ 7,616 $ 7,500 Leasehold improvements 4,727 4,727 Office furniture and equipment 246 234 Construction in progress 30 17 12,619 12,478 Less: accumulated depreciation and amortization (10,547 ) (10,323 ) Total $ 2,072 $ 2,155
Schedule of Accrued Expenses	Accrued expenses consist of (in thousands): March 31, December 31, Accrued clinical and related costs $ 6,219 $ 5,377 Accrued compensation and related taxes 1,820 3,591 Accrued other 662 173 Total $ 8,701 $ 9,141

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following fair value hierarchy tables present information about each major category of our financial assets and liabilities measured at fair value on a recurring basis (in thousands): Fair Value Measurement at March 31, 2018 Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ 42,639 $ 42,639 $ — $ — Fair Value Measurement at December 31, 2017 Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ 55,245 $ 55,245 $ — $ —

Common Stock and Stock Warran18

Common Stock and Stock Warrants (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Shares Reserved for Future Issuance	Shares reserved for future issuance at March 31, 2018 are as follows: Number of Shares Common stock options outstanding 7,740,808 Common stock options available for future grant: 2014 Equity Incentive Plan 56,506 2017 Inducement Equity Incentive Plan 261,168 Common stock warrants 240,620 Total common shares reserved for future issuance 8,299,102

Stock Compensation Plans (Table

Stock Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity under the 2012 Plan, 2014 Plan and the Inducement Plan: Options Weighted- Weighted- Aggregate Outstanding as of January 1, 2018 6,083,482 $ 6.76 Granted 1,669,104 $ 6.31 Exercised — $ — Forfeited or expired (11,778 ) $ 5.74 Outstanding as of March 31, 2018 7,740,808 $ 6.66 7.35 $ 9,639,492 Options vested and expected to vest as of March 31, 2018 7,579,288 $ 6.68 7.31 $ 9,434,249 Options exercisable as of March 31, 2018 3,704,451 $ 7.92 5.56 $ 3,152,405
Ranges of Underlying Assumptions Used in BSM Option Pricing Model to Determine Fair Value of Stock Options Granted to Employees and Nonemployees	The following are the ranges of underlying assumptions used in the BSM option pricing model to determine the fair value of stock options granted to employees and to non-employees under all stock plans: Three Months Ended March 31, 2018 2017 Employees: Risk-free interest rate 2.0% - 2.1% 1.5% Expected dividend yield 0% 0% Expected volatility 79.8% - 82.0% 85.4% Expected term of options (years) 6.1 5.9 Fair value of common stock $6.30 - $6.45 $5.05 Non-employees: Risk-free interest rate 2.1% - 2.7% 1.0% - 1.9% Expected dividend yield 0% 0% Expected volatility 73.4% - 80.9% 75.6% - 83.3% Expected term of options (years) 0.4 - 9.3 1.3 - 4.5 Fair value of common stock $6.45 - $6.80 $4.00
Schedule of Stock-based Compensation Expense for Stock Awards Recognized	Total stock-based compensation expense for all stock awards recognized in our condensed consolidated statements of operations is as follows (in thousands): Three Months 2018 2017 Employees: Research and development $ 389 $ 460 General and administrative 1,044 787 Total $ 1,433 $ 1,247 Non-employees: Research and development $ 51 $ 16 General and administrative 69 — Total $ 120 $ 16

Description of Business and B20

Description of Business and Basis of Financial Statements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Accumulated deficit	$ 310,341	$ 295,953
Cash and cash equivalents	43,647	$ 56,901	$ 86,636	$ 59,991
Amount available for issuance	112,500
At-The-Market Sales Agreement
Class of Stock [Line Items]
Maximum aggregate offering price of securities	$ 62,200

Summary of Significant Accoun21

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Impairment losses	$ 0	$ 0
Expected dividend yield	0.00%
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years

Summary of Significant Accoun22

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (in shares)	7,740,808	4,863,702
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (in shares)	240,620	240,620

Other Financial Information - S

Other Financial Information - Schedule of Property and Equipment, Leasehold Improvements, and Related Accumulated Depreciation and Amortization (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 12,619	$ 12,478
Less: accumulated depreciation and amortization	(10,547)	(10,323)
Property and equipment, net	2,072	2,155
Manufacturing, clinical and laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,616	7,500
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,727	4,727
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	246	234
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 30	$ 17

Other Financial Information - A

Other Financial Information - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and amortization expense	$ 224	$ 335

Other Financial Information -25

Other Financial Information - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued clinical and related costs	$ 6,219	$ 5,377
Accrued compensation and related taxes	1,820	3,591
Accrued other	662	173
Total	$ 8,701	$ 9,141

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Total rent, property taxes and routine maintenance expense under operating leases	$ 298	$ 255
Current deferred rent	72		$ 91
Long-term deferred rent	$ 47		$ 59

Fair Value - Schedule of Financ

Fair Value - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - Money market funds - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Assets	$ 42,639	$ 55,245
Level 1
Assets
Assets	42,639	55,245
Level 2
Assets
Assets	0	0
Level 3
Assets
Assets	$ 0	$ 0

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 0	$ 0

Common Stock and Stock Warran29

Common Stock and Stock Warrants - Shelf Registration Statement and Private Placement of Common Stock (Detail) - USD ($)	3 Months Ended		32 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	May 31, 2015
Equity [Abstract]
Maximum Aggregate Offering Price of Securities Under Shelf Registration				$ 200,000,000
Class of Stock [Line Items]
Aggregate offering price	$ 112,500,000
Maximum common stock shares authorized (in shares)				2,500,000
Amount remaining to be offered				$ 75,000,000
Gross proceeds from additional offering			$ 74,700,000
Proceeds from issuance of common stock	0	$ 37,825,000
At-The-Market Sales Agreement
Class of Stock [Line Items]
Gross proceeds from additional offering			$ 12,800,000
Maximum aggregate offering price of securities	$ 62,200,000

Common Stock and Stock Warran30

Common Stock and Stock Warrants Common Stock and Stock Warrants - Common Stock Issued for Services (Details) - USD ($)	Oct. 30, 2017	Mar. 31, 2018	Mar. 31, 2017
Class of Stock [Line Items]
Common stock issued for services, expense recognized in general and administrative		$ 89,000	$ 0
Restricted Stock
Class of Stock [Line Items]
Common stock issued for services (in shares)	60,000
Expense recognition period	180 days	180 days
Percent of shares to be surrendered at termination	40.00%
Shares quoted at market price (in shares)	36,000
Percent of shares quoted at market price	60.00%
Common stock issued for services	$ 207,000
Market price of shares (in usd per share)	$ 5.75
Shares adjusted to fair value (in shares)		24,000

Common Stock and Stock Warran31

Common Stock and Stock Warrants - Warrants (Details)	Mar. 31, 2018$ / sharesshares
Class of Stock [Line Items]
Exercise price of warrants (in USD per share) | $ / shares	$ 92.99
Common stock warrants
Class of Stock [Line Items]
Number of warrants outstanding (in shares) | shares	240,620

Common Stock and Warrants - Sha

Common Stock and Warrants - Shares Reserved for Future Issuance (Details)	Mar. 31, 2018shares
Class of Stock [Line Items]
Total common shares reserved for future issuance (in shares)	8,299,102
Common stock options outstanding
Class of Stock [Line Items]
Total common shares reserved for future issuance (in shares)	7,740,808
Common stock warrants
Class of Stock [Line Items]
Total common shares reserved for future issuance (in shares)	240,620
2014 Equity Incentive Plan | Common stock options available for future grant:
Class of Stock [Line Items]
Total common shares reserved for future issuance (in shares)	56,506
2017 Inducement Equity Incentive Plan | Common stock options available for future grant:
Class of Stock [Line Items]
Total common shares reserved for future issuance (in shares)	261,168

Stock Compensation Plans - Addi

Stock Compensation Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Apr. 16, 2018	Oct. 31, 2015	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Nov. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			1,669,104
Expiration period from grant date			10 years
Performance-based stock options outstanding (in shares)			7,740,808		6,083,482
Weighted-average grant date fair value of stock options granted (usd per share)			$ 4.40	$ 3.48
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to unvested employee stock option awards			$ 11.4
Remaining weighted-average vesting period			2 years 6 months
Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to unvested employee stock option awards			$ 1.1
Remaining weighted-average vesting period			1 year 9 months 18 days
Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant			261,168			1,850,000
Granted (in shares)			1,588,832
2012 Stock Option Plan And 2014 Equity Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period			1 year
2012 Stock Option Plan And 2014 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period			4 years
2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares repurchased			0
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock for annual increase in shares available for issuance			1,200,000
Percentage of outstanding shares of common stock for annual increase in shares available for issuance			3.00%
Shares available for grant			56,506
Performance-Based Employee Stock Options | 2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period		3 years
Expiration period from grant date			10 years
Performance-based stock options outstanding (in shares)			651,140
Exercise price, lower range			$ 4.57
Exercise price, upper range			$ 7.69
Share-based Compensation Award, Tranche One | Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			25.00%
Share-based Compensation Award, Tranche Two | Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			25.00%
Share-based Compensation Award, Tranche Three | Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			25.00%
Share-Based Compensation Award, Tranche Four | Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			25.00%
Subsequent Event | 2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock for annual increase in shares available for issuance	1,200,000

Stock Compensation Plans - Summ

Stock Compensation Plans - Summary of Stock Option Activity (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares
Options
Outstanding, Beginning balance (in shares) | shares	6,083,482
Granted (in shares) | shares	1,669,104
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	(11,778)
Outstanding, Ending balance (in shares) | shares	7,740,808
Options vested and expected to vest, Ending balance (in shares) | shares	7,579,288
Options exercisable, Ending balance (in shares) | shares	3,704,451
Weighted- Average Exercise Price
Outstanding, Beginning balance (usd per share) | $ / shares	$ 6.76
Granted (usd per share) | $ / shares	6.31
Exercised (usd per share) | $ / shares	0
Forfeited or expired (usd per share) | $ / shares	5.74
Outstanding, Ending balance (usd per share) | $ / shares	6.66
Options vested and expected to vest, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	6.68
Options exercisable, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	$ 7.92
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, Weighted-Average Remaining Contractual Term, Ending balance	7 years 4 months 6 days
Options vested and expected to vest , Weighted-Average Remaining Contractual Term, Ending balance	7 years 3 months 22 days
Options exercisable, Weighted-Average Remaining Contractual Term, Ending balance	5 years 6 months 22 days
Outstanding, Aggregate Intrinsic Value, Ending balance | $	$ 9,639,492
Options vested and expected to vest , Aggregate Intrinsic Value, Ending balance | $	9,434,249
Options exercisable, Aggregate Intrinsic Value, Ending balance | $	$ 3,152,405

Stock Compensation Plans - Rang

Stock Compensation Plans - Ranges of Underlying Assumptions Used in BSM Option Pricing Model to Determine Fair Value of Stock Options Granted to Employees and Nonemployees (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate		1.50%
Risk-free interest rate, minimum	2.00%
Risk-free interest rate, maximum	2.10%
Expected dividend yield	0.00%	0.00%
Expected volatility		85.40%
Expected volatility, minimum	79.80%
Expected volatility, maximum	82.00%
Expected term of options (years)	6 years 1 month 6 days	5 years 10 months 24 days
Fair value of common stock		$ 5.05
Employees | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock	$ 6.30
Employees | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock	$ 6.45
Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	2.10%	1.00%
Risk-free interest rate, maximum	2.70%	1.90%
Expected dividend yield	0.00%	0.00%
Expected volatility, minimum	73.40%	75.60%
Expected volatility, maximum	80.90%	83.30%
Fair value of common stock		$ 4
Non-Employees | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of options (years)	4 months 24 days	1 year 3 months 18 days
Fair value of common stock	$ 6.45
Non-Employees | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of options (years)	9 years 3 months 18 days	4 years 6 months
Fair value of common stock	$ 6.80

Stock Compensation Plans - Sche

Stock Compensation Plans - Schedule of Stock-based Compensation Expense for Stock Awards Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,553	$ 1,263
Employees
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,433	1,247
Employees | Research and Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	389	460
Employees | General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,044	787
Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	120	16
Non-Employees | Research and Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	51	16
Non-Employees | General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 69	$ 0