Achaogen (AKAOQ) 10-K 14 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Mar. 01, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	AKAO
Entity Registrant Name	Achaogen Inc
Entity Central Index Key	1,301,501
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		35,781,564
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 75.5

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 118,964	$ 20,287
Short-term investments	26,912	38,444
Contracts receivable	12,151	5,039
Prepaids and other current assets	2,189	1,719
Restricted cash	127	0
Total current assets	160,343	65,489
Property and equipment, net	3,261	905
Restricted cash	250	127
Deposit and other assets	71	342
Total assets	163,925	66,863
Current liabilities:
Accounts payable	5,739	3,537
Accrued liabilities	9,698	4,927
Loan payable, current portion	4,167	0
Other current liabilities	104	225
Total current liabilities	19,708	8,689
Loan payable, long-term	21,110	14,536
Warrant liability	13,874	0
Derivative liability	602	375
Deferred Rent	1,896	104
Total liabilities	57,190	23,704
Commitments and contingencies (Note 7)
Stockholders’ equity:
Common stock, $0.001 par value, 290,000,000 shares authorized, 35,638,052 and 18,395,219 shares issued and outstanding at December 31, 2016 and 2015, respectively	35	18
Preferred stock, $0.001 par value, 10,000,000 shares authorized, no shares issued and outstanding	0	0
Additional paid-in capital	353,927	219,182
Accumulated deficit	(247,220)	(175,993)
Accumulated other comprehensive loss	(7)	(48)
Total stockholders’ equity	106,735	43,159
Total liabilities and stockholders’ equity	$ 163,925	$ 66,863

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Common stock, par value (dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	290,000,000	290,000,000
Common stock, shares issued	35,638,052	18,395,219
Common stock, shares outstanding	35,638,052	18,395,219
Preferred stock, par value (dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Contract revenue	$ 41,773	$ 26,061	$ 19,970
Operating expenses:
Research and development	73,999	40,228	30,110
General and administrative	17,122	12,406	9,646
Total operating expenses	91,121	52,634	39,756
Loss from operations	(49,348)	(26,573)	(19,786)
Interest expense	(2,320)	(699)	(397)
Change in warrant and derivative liabilities	(19,859)	(19)
Other income, net	300	198	7
Net loss	$ (71,227)	$ (27,093)	$ (20,176)
Basic and diluted net loss per common share	$ (3)	$ (1.49)	$ (1.42)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	23,707,063	18,147,986	14,210,098

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (71,227)	$ (27,093)	$ (20,176)
Other comprehensive loss:
Net unrealized gain (loss) on available-for-sale securities	41	(16)	(32)
Total comprehensive loss	$ (71,186)	$ (27,109)	$ (20,208)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Underwriter	Private Placement	Convertible Preferred Stock	Common Stock	Common StockUnderwriter	Common StockPrivate Placement	Additional Paid-In Capital	Additional Paid-In CapitalUnderwriter	Additional Paid-In CapitalPrivate Placement	Accumulated Deficit	Accumulated Other Comprehensive Loss
Convertible preferred stock, beginning balance (in shares) at Dec. 31, 2013				9,796,342
Convertible preferred stock, beginning balance at Dec. 31, 2013				$ 132,278
Beginning balance (in shares) at Dec. 31, 2013					392,844
Beginning balance at Dec. 31, 2013	$ (124,576)							$ 4,148			$ (128,724)
Increase (Decrease) in Stockholders' Equity:
Conversion of preferred stock to common stock upon initial public offering (in shares)				(9,796,342)	10,386,894
Conversion of preferred stock to common stock upon initial public offering	132,278			$ (132,278)	$ 11			132,267
Issuance of common stock upon initial public offering, net of issuance costs (in shares)					6,900,000
Issuance of common stock upon initial public offering, net of issuance costs	73,936				$ 7			73,929
Issuance of common stock upon exercise of warrant (in shares)					909
Issuance of common stock upon exercise of warrant	2							2
Issuance of common stock under stock plans (in shares)					208,693
Issuance of common stock under stock plans	706							706
Issuance of common stock under ESPP (in shares)					17,795
Issuance of common stock under ESPP	139							139
Reclassification of warrant liability to additional paid-in capital	286							286
Stock-based compensation expense	2,050							2,050
Unrealized gain (loss) on available-for-sale securities, net of taxes	(32)											$ (32)
Net loss	(20,176)										(20,176)
Ending balance at Dec. 31, 2014	64,613				$ 18			213,527			(148,900)	(32)
Ending balance (in shares) at Dec. 31, 2014					17,907,135
Increase (Decrease) in Stockholders' Equity:
Issuance of common stock upon initial public offering, net of issuance costs (in shares)					197,838
Issuance of common stock upon initial public offering, net of issuance costs	1,319							1,319
Issuance of common stock under stock plans (in shares)					228,504
Issuance of common stock under stock plans	1,053							1,053
Issuance of common stock under ESPP (in shares)					61,742
Issuance of common stock under ESPP	300							300
Stock-based compensation expense	2,983							2,983
Unrealized gain (loss) on available-for-sale securities, net of taxes	(16)											(16)
Net loss	(27,093)										(27,093)
Ending balance at Dec. 31, 2015	$ 43,159				$ 18			219,182			(175,993)	(48)
Ending balance (in shares) at Dec. 31, 2015	18,395,219				18,395,219
Beginning balance (in shares) at Dec. 31, 2014					17,907,135
Beginning balance at Dec. 31, 2014	$ 64,613				$ 18			213,527			(148,900)	(32)
Ending balance at Dec. 31, 2016	$ 106,735				$ 35			353,927			(247,220)	(7)
Ending balance (in shares) at Dec. 31, 2016	35,638,052				35,638,052
Beginning balance (in shares) at Dec. 31, 2015	18,395,219				18,395,219
Beginning balance at Dec. 31, 2015	$ 43,159				$ 18			219,182			(175,993)	(48)
Increase (Decrease) in Stockholders' Equity:
Issuance of common stock upon initial public offering, net of issuance costs (in shares)					907,711	7,475,000	7,999,996
Issuance of common stock upon initial public offering, net of issuance costs	3,827	$ 94,547	$ 22,587		$ 1	$ 7	$ 8	3,826	$ 94,540	$ 22,579
Issuance of common stock upon exercise of warrant (in shares)					610,490
Issuance of common stock upon exercise of warrant	9,488				$ 1			9,487
Issuance of common stock under stock plans (in shares)					103,912
Issuance of common stock under stock plans	65							65
Issuance of common stock under ESPP (in shares)					145,724
Issuance of common stock under ESPP	401							401
Reclassification of warrant liability to additional paid-in capital	8,337
Stock-based compensation expense	3,847							3,847
Unrealized gain (loss) on available-for-sale securities, net of taxes	41											41
Net loss	(71,227)										(71,227)
Ending balance at Dec. 31, 2016	$ 106,735				$ 35			$ 353,927			$ (247,220)	$ (7)
Ending balance (in shares) at Dec. 31, 2016	35,638,052				35,638,052

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (71,227,000)	$ (27,093,000)	$ (20,176,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	441,000	426,000	358,000
Amortization of premium on short-term investments	304,000	500,000	257,000
Stock-based compensation expense	3,847,000	2,983,000	2,050,000
Revaluation of convertible preferred stock warrant			42,000
Change in warrant and derivative liabilities	19,859,000	19,000
Non-cash interest expense relating to notes payable	741,000	302,000	209,000
Change in operating assets and liabilities:
Contracts receivable	(7,112,000)	195,000	1,996,000
Prepaids and other assets	(199,000)	(1,504,000)	1,397,000
Accounts payable and accrued liabilities	6,668,000	3,076,000	(539,000)
Other liabilities	(225,000)	8,000	123,000
Net cash used in operating activities	(46,903,000)	(21,088,000)	(14,283,000)
Cash flows from investing activities:
Purchase of property and equipment	(901,000)	(606,000)	(340,000)
Purchase of short-term investments	(30,961,000)	(41,851,000)	(45,087,000)
Maturities of short-term investments	42,230,000	47,689,000
Net cash provided by (used in) investing activities	10,368,000	5,232,000	(45,427,000)
Cash flows from financing activities:
Proceeds from initial public offering, net of issuance costs			73,936,000
Proceeds from underwritten public offering, net of issuance costs	94,852,000
Proceeds from private placement, net of issuance costs	25,166,000
Proceeds from sales of common stock, net of issuance costs	3,827,000	1,319,000
Proceeds from the issuance of common stock in connection with equity incentive plans	466,000	1,353,000	811,000
Proceeds from exercise of stock warrants	1,151,000		2,000
Proceeds from loan payable, net of issuance costs	10,000,000	14,590,000
Repayment of notes payable			(6,896,000)
Net cash provided by financing activities	135,462,000	17,262,000	67,853,000
Net increase in cash, cash equivalents, and restricted cash	98,927,000	1,406,000	8,143,000
Cash, cash equivalents, and restricted cash at beginning of year	20,414,000	19,008,000	10,865,000
Cash, cash equivalents, and restricted cash at end of year	119,341,000	20,414,000	19,008,000
Supplemental disclosures of cash flow information
Interest paid	1,579,000	396,000	221,000
Supplemental disclosures of noncash investing and financing information
Conversion of convertible preferred stock into common stock			132,278,000
Reclassification of warrant liability to additional paid-in capital	8,337,000		$ 286,000
Accrued and deferred public offering issuance cost	305,000
Issuance of derivative in connection with issuance of loan payable		$ 356,000
Purchases of property plant and equipment included in deferred rent	$ 1,896,000

Organization and Basis of Prese

Organization and Basis of Presentation and Consolidation	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation and Consolidation	1. Organization and Basis of Presentation and Consolidation Achaogen, Inc. (together with its consolidated subsidiary, the “Company”) is a late-stage biopharmaceutical company passionately committed to the discovery, development, and commercialization of novel antibacterial treatments against multi-drug resistant gram-negative infections. The Company is developing plazomicin, its lead product candidate, for the treatment of bacterial infections due to multi-drug resistant Enterobacteriaceae, including carbapenem-resistant Enterobacteriaceae (“CRE”). The Company’s Phase 3 study of plazomicin in the treatment of patients with complicated urinary tract infections (“cUTI”) and acute pyelonephritis (“AP”), entitled EPIC (Evaluating Plazomicin In cUTI), is expected to serve as a single pivotal study supporting a new drug application (“NDA”) for plazomicin in the United States. In addition, the Company’s Phase 3 study of plazomicin, the CARE (Combating Antibiotic Resistant Enterobacteriaceae) trial, which is a resistant pathogen-specific trial designed to evaluate the efficacy and safety of plazomicin in patients with infections due to CRE. The Company was incorporated in Delaware in 2002 and commenced operations in 2004. Since commencing operations in 2004, the Company has devoted substantially all its resources to identifying and developing its product candidates, including conducting preclinical studies and clinical trials and providing general and administrative support for these operations. Reclassifications The change in derivative liability for the year ended December 31, 2015 has been reclassified to be included in the change in warrant and derivative liabilities to conform to the current year’s presentation. Such reclassifications did not impact the Company’s net loss or financial position. Basis of Presentation and Consolidation The consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the consolidated accounts of the Company and its subsidiary. Intercompany accounts and transactions have been eliminated in consolidation. During 2012, the Company established a wholly owned foreign subsidiary in the United Kingdom. There have been no significant activities for this entity during the fiscal years ended December 31, 2016, 2015 and 2014. In March 2014, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 6,900,000 shares of common stock, which includes 900,000 shares issued pursuant to the over-allotment option granted to its underwriters, and received net proceeds of approximately $73.9 million, after deducting underwriting discounts, commissions and offering expenses. In connection with the completion of the Company's IPO, all shares of convertible preferred stock converted into 10,386,894 shares of common stock and all of the Company's convertible preferred stock warrants were converted into warrants to purchase common stock. On April 7, 2015, the Company filed a Registration Statement on Form S-3, declared effective by the SEC on April 21, 2015, covering the offering of up to $150.0 million of common stock, preferred stock, debt securities, warrants, purchase contracts and/or units. This Registration Statement included a prospectus covering the offering, issuance and sale of up to $30.0 million of shares of the Company’s common stock from time to time in an “at-the-market” (“ATM”) equity offering pursuant to a sales agreement with Cowen and Company, LLC. As of December 31, 2016, the Company had sold 1,105,549 shares pursuant to its ATM equity offering program at a weighted-average price of $4.82 per share for aggregate offering proceeds of $5.3 million and aggregate net proceeds of $5.1 million, after deducting the sales commissions and offering expenses. On June 3, 2016, the Company sold 7,999,996 shares of its common stock and warrants to purchase 1,999,999 shares of its common stock pursuant to Securities Purchase Agreement (the "Purchase Agreement") for aggregate gross proceeds of $25.4 million and aggregate net proceeds of $25.1 million, after deducting the issuance costs, in connection with a private placement financing transaction (the "Private Placement"). The warrants have an exercise price of $3.66 per share and are exercisable up to five years from the date of issuance. On December 19, 2016, the Company completed an underwritten public offering of common stock made under a prospectus supplement and related prospectus pursuant to the Shelf Registration Statement. This offering resulted in the sale of 7,475,000 shares, at a price of $13.50 per share, including the full exercise of the underwriter’s option to purchase an additional 975,000 shares of common stock. The Company received net proceeds from the offering of $94.6 million, after deducting the underwriting discounts and commissions and estimated offering expenses. The Company has incurred losses and negative cash flows from operations every year since its inception. As of December 31, 2016, the Company had unrestricted cash, cash equivalents and short-term investments of approximately $145.9 million and an accumulated deficit of approximately $247.2 million. Management expects that, based on its current operating plans, the Company’s existing cash, cash equivalents and short-term investments as of December 31, 2016, combined with the committed funds from the BARDA and NIAID contracts, will be sufficient to fund its current planned operations for at least the next twelve months from the issuance of this report. Management plans to raise additional funds through equity or debt financing arrangements, government contracts, and/or third party collaboration funding in the future to fund its operations, including the commercial launch of plazomicin. However, there can be no assurance that such funding sources will be available at terms acceptable to the Company or at all. If the Company is unable to raise additional funding to meet its working capital needs, it will be forced to delay or reduce the scope of its research programs and/or limit or cease its operations. The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The accompanying financial statements have been prepared in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosures of contingent liabilities. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of derivative and warrant liabilities, common stock and stock-based awards and income taxes. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates. Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments, including cash and cash equivalents, contracts receivable, prepaid and other current assets, accounts payable, accrued liabilities, and other current liabilities approximate fair value due to their short-term maturities. Short-term investments consist of available-for-sale securities as of December 31, 2016 and are carried at fair value. Based upon the borrowing rates currently available to the Company for loans with similar terms, the Company believes the carrying amounts of the loan payable and the derivative liability also represent fair values. Cash and Cash Equivalents Cash equivalents include only securities having an original maturity of three months or less at the time of purchase. As of December 31, 2016 and 2015, cash and cash equivalents consisted of bank deposits, cash, and investments in money market funds. Short-term Investments Short-term investments consist of debt securities with maturities greater than three months, but less than one year from the date of acquisition, and are classified as available for sale. Short-term investments are carried at fair value. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of net unrealized losses on available-for-sale securities in the Company's consolidated statements of comprehensive loss. The amortized cost of debt securities reflects amortization of purchase premiums and accretion of purchase discounts to date, which is included in interest income. The Company reviews all of its marketable securities on a regular basis to evaluate whether any security has experienced an other-than-temporary decline in fair value. Restricted Cash At December 31, 2016 and December 31, 2015, the Company had restricted cash of $377,000 and $127,000. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): Year Ended December 31, 2016 2015 2014 Cash and cash equivalents $ 118,964 $ 20,287 $ 18,881 Restricted cash, current 127 - - Restricted cash, non current 250 127 127 Total cash, cash equivalents, and restricted cash $ 119,341 $ 20,414 $ 19,008 The restricted cash, which consists of money market accounts with one of the Company’s financial institutions, serves as collateral for the letters of credit provided as security deposits under the Company’s facility leases. As of December 31, 2016, $127,000 of restricted cash is classified as current assets and relates to the current facility lease that expires on April 14, 2017. Segment Reporting 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 in making decisions regarding resource allocation and assessing performance. The Company has one operating segment. Customer Concentration For the years ended December 31, 2016, 2015 and 2014, all of the Company’s revenue has been generated solely from funding pursuant to U.S. government contracts, and accordingly all contracts receivable relate to funding from U.S. government contracts. Concentration of Credit Risk Financial instruments that potentially subject the Company to a significant concentration of credit risk consist of cash, cash equivalents and short-term investments. Cash and cash equivalents are deposited in checking and money market accounts at one financial institution, which at times, may exceed federally insured limits. Management believes that the financial institution is financially sound, and, accordingly, minimal credit risk exists with respect to this financial institution. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of default by the institutions holding its cash and cash equivalents or issuing the debt securities. As of December 31, 2016, the Company has not experienced any credit losses in such accounts or investments. Contracts Receivable Contracts receivable represent amounts owed to the Company under certain government contracts. The Company had no amounts reserved for doubtful accounts as of December 31, 2016 and 2015, as the Company expects full collection of the receivable balances. Property and Equipment, Net Property and equipment consists of office equipment, laboratory equipment, and leasehold improvements and is stated at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized over their estimated useful lives or the remaining lease term, whichever is shorter. Maintenance and repair costs are recorded as a component of operating expenses in the Company’s consolidated statement of operations when incurred. Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment charge is determined based upon the excess of the carrying value of the asset over its estimated fair value, with estimated fair value determined based upon an estimate of discounted future cash flows or other appropriate measures of estimated fair value. For the years ended December 31, 2016, 2015 and 2014, the Company did not have any impairment charges. Convertible Preferred Stock Warrant Liabilities The Company accounted for its Series A and Series C convertible preferred stock warrants as freestanding warrants for shares that are puttable or redeemable. At December 31, 2013, these warrants were classified as liabilities on the consolidated balance sheet at their estimated fair value. At the end of each reporting period, changes in estimated fair value during the period were recorded as a component of other income, net. At the time of the IPO, the warrants to purchase preferred stock were converted into warrants to purchase common stock, which are no longer subject to remeasurement, and the preferred stock warrant liability was reclassified to additional paid-in capital at its then fair value. Warrant Liability On June 3, 2016, the Company issued warrants to purchase 1,999,999 shares of its common stock in connection with the Private Placement. Each warrant has an exercise price of $3.66 per share and is exercisable for five years from the date of issuance. The Company accounts for these warrants as a liability instrument measured at estimated fair value. The initial fair value of the warrants was determined using a calibration model that involved using the Black-Scholes Pricing Model ("Black-Scholes"), which requires inputs such as the risk-free interest rate, expected share price volatility, underlying price per share of the Company's common stock and remaining term of the warrants. The warrants are subject to remeasurement at each balance sheet date, using Black-Scholes, with any changes in the fair value of the outstanding warrants recognized in the condensed consolidated statements of operations. Stock-Based Compensation The Company measures and recognizes the compensation expense for all stock-based awards made to employees and directors, including employee stock options, stock grants and employee stock purchases related to the Employee Stock Purchase Plan (“ESPP”) based on estimated fair values. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock option and ESPP awards with time-based vesting terms. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of complex and subjective variables. The fair value of restricted stock unit (“RSU”) awards with time-based vesting terms is based on the grant date share price. The Company recognizes stock-based compensation cost over the award’s requisite service period on a straight-line basis for time-based awards and on a graded basis for awards that are contingent on the achievement of market-based conditions. The Company records stock-based compensation expense, net of the estimated impact of forfeited awards. As such, the Company recognizes stock-based compensation expense only for those stock-based awards that are expected to vest over their requisite service period, based on the vesting provisions of the individual underlying grants. During 2016 and 2014, the Company issued stock-based option awards with market-based conditions that vest upon achievement of certain market price thresholds of the Company’s common stock. The estimated fair value for market-based stock option awards is determined using a lattice valuation model with a Monte-Carlo simulation. The model takes into consideration the historical volatility of the Company’s stock and the risk-free interest rate at the date of grant. In addition, the model is used to estimate the derived service period for the awards. The derived service period is the estimated period of time that would be required to satisfy the market condition, assuming the market condition will be satisfied. Stock-based compensation expense is recognized over the implicit service period derived from the Monte-Carlo simulation model, as applicable, but is accelerated if the market condition is achieved earlier than estimated. For non-employee stock-based awards, the measurement date on which the estimated fair value of the stock-based award is calculated is equal to the earlier of (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. The Company recognizes stock-based compensation expense for the estimated fair value of the vested portion of non-employee awards. Revenue Recognition The Company recognizes revenue when: (i) evidence of an arrangement exists, (ii) fees are fixed or determinable, (iii) services have been delivered, and (iv) collectability is reasonably assured. The Company currently generates revenue entirely from government contracts. Government contracts provide the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from government contracts is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the government contracts have been met. Costs of contract revenue are recorded as a component of operating expenses in the Company’s consolidated statements of operations. Funds received from third parties under contract arrangements are recorded as revenue if the Company is deemed to be the principal participant in the contract arrangements because the activities under the contracts are part of the Company’s development programs. If the Company is not the principal participant, the funds from contracts are recorded as a reduction to research and development expense. Contracts funds received are not refundable and are recognized when the related qualified research and development costs are incurred and when there is reasonable assurance that the funds will be received. Funds received in advance are recorded as deferred revenue. Management has determined that the Company is the principal participant under the Company’s government contract arrangements, and accordingly, the Company records amounts earned under the arrangements as revenue. Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses include certain payroll and personnel expenses, laboratory supplies, consulting costs, external contract research and development expenses, and allocated overhead, including rent, equipment depreciation, and utilities and relate to both Company-sponsored programs as well as costs incurred pursuant to collaboration agreements and government contracts. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and recognized as an expense as the goods are delivered or the related services are performed. For certain research and development services where the Company has not yet been invoiced or otherwise notified of actual cost from the third-party contracted service providers, the Company is required to estimate the extent of the services that have been performed on the Company’s behalf and the associated costs incurred at each reporting period. The majority of the service providers invoice the Company monthly in arrears for services performed. The Company make estimates of the accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to the Company at that time. The Company periodically confirm the accuracy of the estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include services from: • CROs and other service providers in connection with clinical studies; • contract manufacturers in connection with the production of clinical trial materials; and • vendors in connection with preclinical development activities. The Company bases the expenses related to preclinical studies and clinical trials on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage such studies and trials on the Company’s behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows and expense recognition. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing service fees, the Company estimates the time period over which these services will be performed and the level of effort to be expended and costs to be incurred during each reporting period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts the accrual accordingly. The Company’s estimation of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting changes in estimates in any particular period. To date, there have been no material adjustments from the Company’s estimates to the amount actually incurred. Leases The Company has entered into lease agreements for its laboratory and office facilities. These leases qualify as and are accounted for as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease and, accordingly, the Company records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Incentives granted under the Company’s facilities leases, including allowances to fund leasehold improvements and rent holidays, are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease. Income Taxes The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company assesses the need for a valuation allowance against the Company’s deferred income tax assets by considering both positive and negative evidence related to whether it is more likely than not that the deferred income tax assets will be realized. In evaluating its ability to recover the deferred income tax assets within the jurisdiction from which they arise, the Company considered all available positive and negative evidence, including scheduled reversals of deferred income tax liabilities, projected future taxable income, tax-planning strategies, and results of recent operations. Due to the Company’s considerations, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits. The tax benefit recognized in the financial statements for a particular tax position is the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company's policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. Net Loss and Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per common share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common share equivalents outstanding during the period. Because the Company has reported a net loss for the years ended December 31, 2016, 2015 and 2014, diluted net loss per common share is the same as basic net loss per common share for those periods. Effective as of the completion of the IPO, all of the Company’s preferred stock was converted to common stock. For purposes of calculating net loss per common share for the year ended December 31, 2014, the preferred stock converted to common stock was included in the net loss per common share calculation on a post-conversion basis based on the conversion date. The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2016, 2015 and 2014 (in thousands, except share and per share amounts): Year Ended December 31, 2016 2015 2014 Net loss $ (71,227 ) $ (27,093 ) $ (20,176 ) Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share 23,707,063 18,147,986 14,210,098 Basic and diluted net loss per common share $ (3.00 ) $ (1.49 ) $ (1.42 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an anti-dilutive impact due to losses reported (in common stock equivalent shares): December 31, 2016 2015 2014 Options to purchase common stock 3,540,293 2,387,337 1,885,372 Restricted stock units 605,052 372,024 168,200 Warrants to purchase common stock 1,322,754 30,024 40,454 Warrants outstanding as of December 31, 2016 have a weighted-average exercise price of $3.85. Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern Going Concern In November 2015, the FASB issued ASU No. 2015-17, Income Taxes Balance Sheet Classification of Deferred Taxes In February 2016, the FASB issued ASU No. 2016-02, Leases In March 2016, the FASB issued ASU No. 2016-06, Derivatives and Hedging Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued ASU No 2016-09, Compensation - Stock Compensation Improvements to Employee Share-Based Payment Accounting In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most current revenue recognition guidance. This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company has not yet finalized its preliminary assessment and conclusions on how the adoption of this ASU will affect its current policies related to revenue recognition. The Company will adopt the new revenue standard on January 1, 2018, and through the remainder of 2017, will continue to assess the potential impact of adopting this new standard on any current, new or significantly modified customer contracts. In subsequent quarters, the Company will finalize its selection of transition methods, and complete its evaluation of additional disclosures that may be required upon adoption of the new standard. In November, 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows Restricted Cash

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash, cash equivalents, contracts receivable, accounts payable, and accrued liabilities, approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at estimated fair value using Level 3 inputs. There were no transfers within the hierarchy during the years ended December 31, 2016 and 2015. Financial instruments Financial assets and liabilities measured and recognized at fair value on a recurring basis were as follows (in thousands): As of December 31, 2016: December 31, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Assets Cash $ 3,728 $ — $ — $ 3,728 Level 1: Restricted cash 377 — — 377 Money market funds 115,236 — — 115,236 Subtotal 115,613 — — 115,613 Level 2: Corporate debt securities 12,969 — (7 ) 12,962 Commercial paper 13,950 — — 13,950 Subtotal 26,919 — (7 ) 26,912 $ 146,260 $ — $ (7 ) $ 146,253 Reported as: Cash and cash equivalents $ 118,964 Short-term investments $ 26,912 Restricted cash $ 377 Liabilities, Level 3 Warrant Liability $ 13,874 Derivative Liability $ 602 Total $ 14,476 As of December 31, 2015: December 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Assets Cash $ 1,013 $ — $ — $ 1,013 Level 1: Restricted cash 127 — — 127 Money market funds 19,274 — — 19,274 Subtotal 19,401 — — 19,401 Level 2: Corporate debt securities 34,490 — (47 ) 34,443 Commercial paper 1,997 — — 1,997 US Treasury bills 2,005 — (1 ) 2,004 Subtotal 38,492 — (48 ) 38,444 Total $ 58,906 $ — $ (48 ) $ 58,858 Reported as: Cash and cash equivalents $ 20,287 Short-term investments $ 38,444 Restricted cash $ 127 Liabilities Level 3: Derivative liability $ 375 All available-for-sale securities held as of December 31, 2016 had contractual maturities of less than one year. There were no sales of available-for-sale securities in any of the periods presented. The fair value of corporate and U.S. Treasury debt obligations that were in unrealized loss positions totaled $13.0 million as of December 31, 2016. The Company has determined that (i) it does not have the intent to sell any of these investments, and (ii) it is not more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. The Company anticipates that it will recover the entire amortized cost basis of such corporate and U.S. Treasury debt obligations and has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the year ended December 31, 2016. Pursuant to the loan and security agreement with Solar Capital Ltd. (see Note 8), the Company entered into a Success Fee Agreement under which the Company agreed to pay $1.0 million (the “Success Fee”) if the Company obtains FDA approval to market plazomicin. If such approval is obtained, the Success Fee shall be due the later of (i) August 5, 2019 or (ii) the date such FDA approval is obtained. The fair value of the Success Fee, approximately $375,000 at December 31, 2015, is recorded as a derivative liability and included in other long-term liabilities on the accompanying consolidated balance sheet. The estimated fair value of the derivative liability as of December 31, 2016 increased by $227,000 to $602,000 from December 31, 2015, primarily as a result of an increased probability of FDA approval to market plazomicin, which is presented as a component of change in warrant and derivative liabilities in the Company’s condensed consolidated statements of operations for the year ended December 31, 2016. The fair value of the derivative liability was determined using a discounted cash flow analysis, and is classified as a Level 3 measurement within the fair value hierarchy since the Company’s valuation utilized significant unobservable inputs. Specifically, the key assumptions included in the calculation of the estimated fair value of the derivative instrument include: i) the Company’s estimates of both the probability and timing of a potential $1.0 million payment to Solar Capital Ltd. upon FDA approval to market plazomicin, and ii) a discount rate of 13% which was derived from the Company's estimated cost of debt. The estimated fair value of the derivative liability is most sensitive to the probability of FDA approval. Should the probability of FDA approval change by 5%, the fair value of the derivative liability as of December 31, 2016 would change by approximately $36,000. For the year ended December 31, 2016, the only change to the key assumption was an increase in the probability of the potential payment, primarily due to the positive results in the Company’s Phase 3 cUTI and CRE clinical trials of plazomicin. Any changes in the estimated fair values are presented as changes in warrant and derivative liabilities in the Company's condensed consolidated statements of operations. Pursuant to the Private Placement (see Note 2), the Company issued warrants to purchase 1,999,999 shares of common stock at an exercise price of $3.66 per share. The Company classified these warrants as a liability measured at fair value using Black-Scholes. Under certain entity conditions, the holder of a warrant may require the Company to settle the warrant in cash at its estimated fair value using Black-Scholes. On the closing date of the Private Placement, June 3, 2016, the $2.6 million initial estimated fair value of the warrants was recorded as a warrant liability on the accompanying condensed consolidated balance sheet. At December 31, 2016, the estimated fair value of the warrants was approximately $13.9 million. The change in the estimated fair value is primarily due to the increase in the Company's stock price, partially offset by the exercise of 707,269 warrants, and is included in changes in warrant and derivative liabilities in the Company's condensed consolidated statements of operations. In December 2016, certain holders of these warrants exercised 707,269 warrants. The Company received $1.2 million in proceeds from these warrant exercises. The Company is required to record the exercised warrants at its estimated fair value at the time of exercise, with any change included in changes in warrant and derivative liabilities in the Company’s condensed consolidated statements of operations. The Company estimated the fair value of these exercised warrants at their respective exercise dates to be $8.3 million, an increase of $7.4 million from its initial valuation, at June 3, 2016, of $0.9 million, primarily due to an increase in the Company’s stock price. In February 2017, certain holders of these warrants exercised 78,585 warrants. The Company received $0.3 million in proceeds from these warrant exercises. The fair value of the warrant liability is classified as a Level 3 measurement within the fair value hierarchy since the Company’s valuation utilized significant unobservable inputs, including the risk-free interest rate, expected share price volatility, underlying price per share of the Company's common stock and remaining term of the warrants. The estimated fair values of the warrants were determined using Black-Scholes with the following assumptions, during the year ended December 31, 2016: Year Ended December 31, 2016 Expected volatility 60% – 80% Expected term 4.4 – 5.0 years Risk-free interest rate 1.0% – 1.9% Dividend yield 0% The expected volatility is based on the Company's expected volatility. The expected term is based on the remaining life of the warrants. The risk-free interest rate is obtained from the yields on actively traded U.S. Treasury securities for a period equal to the expected term of the warrants. The dividend yield is zero because the Company has never paid cash dividends and has no present intention to pay cash dividends. Should the share price change by 5%, the fair value of the warrant liability as of December 31, 2016 would change by approximately $801,000. The convertible preferred stock warrant liabilities and derivative liabilities associated with certain convertible loans were considered Level 3 liabilities. The estimated fair values of the outstanding preferred stock warrant liabilities were measured using the Black-Scholes option-pricing model. The estimated fair value of the derivative liability associated with the convertible loan due to beneficial conversion features (“BCF”), on certain of the Company’s convertible loans was measured by multiplying (1) the intrinsic value of the 20% conversion discount on the effective date and (2) the number of shares converted. The fair value of the convertible preferred stock warrant liabilities was estimated to be $244,000 as of December 31, 2013. In connection with the completion of the Company's IPO in March 2014, all of the outstanding warrants to purchase convertible preferred stock converted into warrants to purchase 40,454 shares of common stock at a weighted-average exercise price of $12.36 per share. The Company remeasured the estimated fair value of these remaining warrants at the date of the conversion and recorded a $42,000 loss related to the change in estimated fair value as part of other income, net, and reclassified the estimated fair value of $286,000 to additional paid-in capital. The following table provides a summary of changes in the estimated fair value of the Company’s liabilities measured at estimated fair value using significant Level 3 inputs for the years ended 2016, 2015 and 2014 (in thousands): Estimated Fair Value of Convertible Preferred Stock Warrant Liabilities Estimated Fair Value of Derivative Liability Estimated Fair Value of Warrant Liability Balance of Level 3 Liabilities at December 31, 2013 $ 244 $ — $ — Change in estimated fair value of convertible preferred stock warrant liabilities 42 — — Reclassification of warrant liability to additional paid-in-capital upon conversion of warrant to purchase convertible preferred stock to warrant to purchase common stock (286 ) — — Balance of Level 3 Liabilities at December 31, 2014 — — — Estimated fair value of derivative liability issued — 356 — Change in estimated fair value of derivative liability — 19 — Balance of Level 3 Liabilities at December 31, 2015 — 375 — Estimated fair value of warrants issued — — 2,579 Change in estimated fair value of warrant liability — — 19,632 Reclassification of warrant liability to additional paid-in-capital upon exercise of warrants (8,337 ) Change in estimated fair value of derivative liability — 227 — Balance of Level 3 Liabilities at December 31, 2016 $ — $ 602 $ 13,874

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, net Property and equipment, net consisted of the following (in thousands): December 31, 2016 2015 Office equipment $ 644 $ 1,144 Laboratory equipment 4,038 3,161 Leasehold improvements 1,072 1,072 Construction-in-progress 1,896 — 7,650 5,377 Less: accumulated depreciation and amortization $ (4,389 ) (4,472 ) Property and equipment, net $ 3,261 $ 905 Depreciation and amortization expense for the years ended December 31, 2016, 2015 and 2014 was $441,000, $426,000 and $358,000, respectively. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): December 31, 2016 2015 Accrued clinical and development expenses $ 3,681 $ 2,869 Payroll and related bonus expenses 4,941 1,615 Other 1,076 443 $ 9,698 $ 4,927

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
License and Collaboration Agreements	5. License and Collaboration Agreements Thermo Fisher Scientific, Inc. In April 2016, the Company entered into an agreement with its collaboration partner, Thermo Fisher Scientific, Inc. (“Thermo Fisher”), to develop and commercialize an assay to support plazomicin. If approved, the Company and Thermo Fisher plan to have a commercial assay for plazomicin available at launch to enable patients to receive safe and efficacious doses of plazomicin. In accordance with the terms of the agreement, the Company is required to make milestone payments with respect to research, development, regulatory and commercialization milestones (if any). All such milestone payments may total, in aggregate, up to but no more than $6,453,000. In further consideration of this agreement, in the event of a successful commercialization of the assay, the Company is required to pay a minimum threshold annual revenue to Thermo Fisher. As of December 31, 2016, the Company has incurred $1,204,000 in milestone payments and the cost was fully recorded as research and development expense. In February 2017, the Company announced the achievement of a strategic milestone in this ongoing collaboration. Crystal Biosciences, Inc. In May 2016, the Company entered into a collaboration and license agreement with Crystal Biosciences, Inc. (“Crystal”). Pursuant to the terms of this agreement, the Company and Crystal agreed to collaborate on the discovery of monoclonal antibodies against multiple targets. Crystal agreed to conduct the initial discovery work with its antibody platform and the Company has the right to develop and commercialize the antibodies discovered through this collaboration. The Company is required to provide signing and milestone payments with respect to research, development, regulatory and commercialization milestones (if any). All such milestone payments may total, in aggregate, up to but no more than $20,550,000. The upfront signing fee, technology access fees and research funding were recorded as research and development expense during the year ended December 31, 2016. This collaboration and license agreement also provides that the Company shall pay royalties equal to a low single-digit percentage of annual worldwide net sales of the commercialized product. Ionis Pharmaceuticals In January 2006, the Company entered into a license agreement with Ionis Pharmaceuticals, Inc. (“Ionis”). Ionis granted the Company an exclusive, worldwide license with the right to grant and authorize sublicenses related to the research and development of aminoglycoside products. As an up-front fee, the Company issued 97,402 shares of preferred Series A convertible stock at a fair value of $15.40 per share. This license fee of $1,500,000 was recorded as research and development expense in 2006. In further consideration of this license, and in accordance with the terms of the agreement, the Company is required to make milestone payments with respect to development, regulatory and commercialization milestones, and to pay a percentage of revenue received from sublicensees (if any). All such milestone and sublicense revenue payments may total, in the aggregate, up to but no more than $19,500,000 for the first product and $9,750,000 following the second product commercialized under the agreement with Ionis. The Company is also required to pay additional milestone payments of up to $20,000,000 in the aggregate upon the first achievement of specified threshold levels of annual net sales of all aminoglycoside products in a calendar year. The license agreement also provides that the Company shall pay royalties equal to a low single-digit percentage of annual worldwide net sales of any licensed products, including, if applicable, plazomicin. In 2014, the Company met its third milestone under the license with Ionis when it dosed the first patients in the Phase 3 CARE trial for plazomicin, and made the milestone payment of $4,000,000, which was recorded as research and development expense. As of December 31, 2016 and 2015, the Company had no outstanding payments due under the agreement.

Government Contracts

Government Contracts	12 Months Ended
	Dec. 31, 2016
Contractors [Abstract]
Government Contracts	6. Government Contracts Certain of the Company’s drug discovery and development activities are performed under contracts with U.S. government agencies. Management has determined that the Company is the principal participant in the following contract arrangements, and, accordingly, the Company records amounts earned under the arrangements as revenue. Costs incurred under revenue contracts are recorded as operating expenses in the Company' consolidated statements of operations. BARDA In August 2010, the Company was awarded a contract with BARDA, for the development, manufacturing, nonclinical and clinical evaluation of, and regulatory filings for, plazomicin as a countermeasure for disease caused by antibiotic-resistant pathogens and biothreats. The original contract included committed funding of $27,600,000 for the first two years of the contract and subsequent options exercisable by BARDA to provide additional funding. In September 2012, BARDA modified the contract to increase the total contract committed funding to $43,398,000 through March 2014. In April 2013, the Company was awarded an additional $60,410,000 under the contract to support its Phase 3 CARE clinical trial of plazomicin which increased the total committed funding under this contract to $103,808,000. On May 26, 2016, the Company was awarded an additional $20 million ("Option 3") under the contract to support its Phase 3 EPIC trial of plazomicin. This brings the total committed funding under the contract to $123,808,000. As of December 31, 2016, $7,227,000 was remaining available from funding committed under this contract. During the years ended December 31, 2016, 2015 and 2014, the Company recognized revenue of $39,462,000, $17,569,000 and $19,970,000, respectively, under this agreement, of which $11,668,000 and $4,657,000 were included in contracts receivable at December 31, 2016, and 2015, respectively. DTRA In November 2012, DTRA, a division of the U.S. Department of Defense, terminated for convenience a contract with the Company that provided funding for the Company's LpxC inhibitor program. In connection with the termination, the Company sought payment from DTRA for additional expenses the Company has incurred. Effective April 30, 2015, the Company reached a settlement of its claim with DTRA. The net settlement of $7,122,000 was recorded as contract revenue during the year ended December 31, 2015. Together with sums previously received, it constitutes complete and final settlement of the contract. NIAID In July 2015, the Company was awarded a contract by NIAID for $1.5 million through June 30, 2016, with total funding up to $4.5 million available if all options are exercised under the contract. In January 2016, an additional committed funding of $0.5 million was added to the awarded funding and the total potential funding was increased to $5.0 million. In April 2016, NIAID modified the contract to exercise an option which increased the total contract committed funding to $4.4 million through February 2018, with total potential funding remaining at $5.0 million if the remaining option is exercised. In July 2014, the Company was awarded a one-year, 407,000 grant by NIAID to conduct discovery research on novel antibiotics targeting gram-negative bacteria. In July 2015, NIAID extended this grant term through July 31, 2016. During the years ended December 31, 2016, 2015 and 2014, the Company recognized revenue of $2,311,000, $1,370,000 and zero, respectively, under these agreements, of which $483,000 and $382,000 were included in contracts receivable at December 31, 2016 and 2015, respectively.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments	7. Commitments Facility Lease Agreement The Company leases its principal executive offices in South San Francisco under a non-cancelable lease agreement that expires on April 14, 2017. In August 2016, the Company entered into a non-cancelable agreement (the "Lease") to lease approximately 47,000 square feet of office, laboratory and research and development space for the Company's new principal executive offices. The Lease is expected to commence in March 2017, after the substantial completion of certain improvements ("Tenant Improvements") required under the Lease, and set to expire in August 2027 ("Lease Term"). The Lease contains expansion options and an option to extend the Lease Term for an additional 5 years. Base rent for the first year of the Lease Term is approximately $2.7 million, with an increase in annual base rent of approximately 3.5% in each subsequent year of the Lease Term. The Lease also provides for rent abatement of approximately $1.8 million for the first year of the Lease Term. The Company is entitled to a one-time improvement allowance of $5.7 million for the Tenant Improvements (the "Allowance"). The Landlord disburses the Allowance for the Tenant Improvement on behalf of the Company. In the event that the Company withdraws from the Lease prior to the commencement of the Lease, the Company will be required to reimburse the Landlord for expenditures incurred related to the Tenant Improvements. As of December 31, 2016, the Company has recorded approximately $1.9 million within construction-in-progress under property, plant and equipment, net and deferred rent in the consolidated balance sheet related to costs incurred under the Allowance. At its election, the Company is also entitled to an additional improvements allowance of $0.9 million ("Additional Allowance"). In the event the Company elects to use the Additional Allowance, the base rent will be increased as calculated in the Lease. Further, the Company had a deposit of $250,000 included in long-term restricted cash as of December 31, 2016, restricted from withdrawal and held in a money market account with one of the Company’s financial institutions in the form of collateral for a letter of credit held as security for the Lease. Future minimum lease payments under the operating leases as of December 31, 2016 are as follows (in thousands): Year-ended December 31, Amounts 2017 $ 1,103 2018 2,500 2019 2,890 2020 2,991 2021 3,098 Thereafter 19,717 Total minimum lease payments $ 32,299 The Company recognizes rent expense on a straight-line basis over the non-cancelable lease period. Aggregate rent expense, net of sublease income, was $581,000, $526,000 and $405,000 for the years ended December 31, 2016, 2015 and 2014, respectively. The Company received $97,000 of sublease income for the year ended December 31, 2014 and none for the years ended December 31, 2015 and 2016. Nonrefundable Advance Payments In July 2015, the Company entered into an agreement with its pharmaceutical contract manufacturing organization that obligates it to make a total of $1,500,000 of nonrefundable advance payments for the reservation of facilities and resources, plus procurement of long lead raw materials, to produce plazomicin for regulatory commercial validation. Such advance payments are initially capitalized as prepaid and other current assets and will be recognized as research and development expenses as goods are delivered and services are performed. The Company assesses such prepaid and other current assets for impairment if events or changes in circumstances indicate that the carrying amount may not be recoverable or may not provide future economic benefits. As of December 31, 2016, the Company had recorded $660,000 as prepaid and other current assets related to this agreement. Through December 31, 2016, the Company has recognized $840,000 as research and development expenses. Commercial Validation and Manufacturing Agreement In March 2017, the Company entered into a commercial validation and manufacturing agreement (“Manufacturing Agreement”). The Manufacturing Agreement includes certain purchase obligations, contingent upon FDA’s approval of plazomicin. For further details, refer to Note 14. Guarantees and Indemnifications As permitted under Delaware law and in accordance with the Company’s bylaws, the Company is required to indemnify its officers and directors for certain events or occurrences while the officer or director is or was serving in such capacity. The Company is also party to indemnification agreements with its directors and officers. The Company believes the fair value of the indemnification rights and agreements is minimal. Accordingly, the Company has not recorded any liabilities for these indemnification rights and agreements as of December 31, 2016 and 2015.

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Borrowings	8. Borrowings Solar Capital Ltd. Loan Agreement On August 5, 2015, the Company entered into a loan and security agreement (the “Loan Agreement”) with Solar Capital Ltd. (the “Lender”) pursuant to which the Lender agreed to make available to the Company term loans in an aggregate principal amount of up to $25.0 million with a maturity date of August 5, 2019. An initial $15.0 million term loan was funded at closing on August 5, 2015, and a second $10.0 million term loan was funded on June 20, 2016. Borrowings under the term loans bear interest per annum at 6.99% plus the greater of 1% or the one-month LIBOR. The Company is currently required to make interest-only payments on the term loans through August 2017, and beginning on September 1, 2017 the Company is required to make monthly payments of interest plus equal monthly payments of principal over a term of 24 months. The Loan Agreement requires collateral by a security interest in all of the Company’s assets except intellectual property (which is subject to a negative pledge) and contains customary affirmative and negative covenants, and also includes standard events of default, including payment defaults. Upon the occurrence of an event of default, a default interest rate of an additional 4% may be applied to the outstanding loan balances, and the Lender may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Loan Agreement. There were no financial covenants attached to the loan. The Loan Agreement included a closing fee of $250,000 which was paid at closing, and the Company is obligated to pay a fee equal to 8% of the term loans funded upon the earliest to occur of the maturity date, the acceleration of the term loans or the voluntary prepayment of the term loans. The cost of these fees is being amortized as interest expense over the term of the loan using the effective-interest method. The Company may voluntarily prepay all, but not less than all, of the outstanding term loans. The Loan Agreement contains customary representations, warranties and covenants. In addition, the Loan Agreement contains customary events of default that entitle the Lender to cause the Company’s indebtedness under the Loan Agreement to become immediately due and payable. On August 5, 2015, pursuant to the Loan Agreement, the Company entered into a Success Fee Agreement with the Lender under which the Company agreed to pay the Lender $1.0 million if the Company obtains FDA approval to market plazomicin. If such approval is obtained, the Success Fee shall be due the later of (i) August 5, 2019 or (ii) the date such FDA approval is obtained. The fair value of the Success Fee at the date of issuance of approximately $356,000 was recorded as a debt discount and is being amortized as interest expense over the term of the loan using the effective-interest method. Future principal debt payments on the loan payable are as follows (in thousands): December 31, 2016 2017 $ 4,167 2018 12,500 2019 8,333 Total principal payments 25,000 Final fee due at maturity in 2019 2,000 Total principal and final fee payments 27,000 Unamortized discount and debt issuance costs (1,723 ) Less current portion (4,167 ) Loan payable, long term $ 21,110 The obligation includes a final fee of $2,000,000, representing 8% of the term loan funded, which accretes over the life of the loan as interest expense. The Company recorded interest expense related to the loan of $2,320,000 and $699,000 for the years ended December 31, 2016 and 2015, respectively. Oxford Finance and SVB Loan Agreement In November 2011, the Company entered into a loan and security agreement (the “Oxford and SVB Loan Agreement”), with Oxford Finance LLC and Silicon Valley Bank (“SVB”) under which the Company borrowed $4,000,000 in November 2011, and $8,000,000 in April 2012. The interest rate, which was fixed at the closing of each tranche, equaled the three-month LIBOR plus 7.75%. The interest rates for the tranches under the Oxford and SVB Loan Agreement were 8.18% and 8.22% per annum. Payments were monthly in arrears and interest only until September 1, 2012, followed by equal monthly payments of principal and interest through June 2014, when the loan was repaid in full. In addition, a final payment equal to 8.25% of the aggregate amount drawn was due upon termination of the Oxford and SVB Loan Agreement, which was accreted as interest expense over the term of the loan using the effective-interest method, with the remaining balance charged to interest expense upon loan repayment. The loan principal balance, accrued interest and the final payment under the Oxford and SVB Loan Agreement totaling $4,454,000 were repaid in full in June 2014. During 2012 and 2011, in connection with the Oxford and SVB Loan Agreement, the Company issued warrants to Oxford Finance LLC and SVB to purchase 20,016 and 10,008 shares, respectively, of its Series C convertible preferred stock at an exercise price of $11.99 per share. The fair value of these warrants at the date of issuance was approximately $163,000 and $86,000, respectively, and was recorded as a debt discount and was amortized as interest expense over the term of the loan using the effective-interest method, with the remaining balance charged to interest expense upon loan repayment. Immediately prior to the closing of the IPO, these warrants automatically converted into warrants exercisable for shares of common stock, resulting in the reclassification of the related preferred stock warrant liabilities to additional paid-in capital. As of December 31, 2016, these warrants remained outstanding and exercisable. The Company recorded interest expense related to the Oxford and SVB Loan Agreement of $397,000 for the year ended December 31, 2014.

Stockholders' Equity and Conver

Stockholders' Equity and Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Stock holders' Equity and Convertible Preferred Stock	9. Stockholders' Equity and Convertible Preferred Stock Stockholders’ Equity On April 7, 2015, the Company entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”), pursuant to which the Company may issue and sell shares of its common stock having aggregate sales proceeds of up to $30.0 million from time to time through an ATM equity program under which Cowen acts as sales agent. As of December 31, 2016, the Company had sold 1,105,549 shares of common stock under the Sales Agreement, at a weighted-average price of approximately $4.82 per share for gross proceeds of $5.3 million and net proceeds of $5.1 million after deducting the sales commissions and offering expenses. As of December 31, 2016, $24.7 million of common stock remained available to be sold under the Sales Agreement, subject to certain conditions specified therein. Convertible Preferred Stock Immediately prior to the completion of the Company’s IPO, all of the outstanding shares of convertible preferred stock automatically converted into 10,386,894 shares of common stock. Each share of Series A, B, C, and D convertible preferred stock converted into common shares at a conversion rate of approximately 1.15, 1.33, 1.00 and 1.00 shares of common stock, respectively. In May 2013, the Company completed the first of two tranches of its Series D round of financing. The majority of the first tranche was received in March 2013 and the Company issued 1,110,252 shares of Series D convertible preferred stock at $11.99 per share to existing investors in exchange for cash proceeds of $10,581,000 and conversion of outstanding loans and accrued interest in the aggregate of $2,732,000 under the 2012 Bridge Loan Agreement. The remaining amount of the first tranche was received in May 2013 from a new investor for additional cash proceeds of $1,778,000 for the issuance of 148,289 shares at a price of $11.99 per share. The second tranche was closed in November 2013. The Company issued 834,031 additional shares of Series D convertible preferred stock at $11.99 per share for gross cash proceeds of $10,000,000. Warrants On June 3, 2016, the Company sold 7,999,996 shares of its common stock and warrants to purchase 1,999,999 shares of its common stock pursuant to the Purchase Agreement for aggregate gross proceeds of $25.4 million in the Private Placement. The warrants have an exercise price of $3.66 per share and are exercisable up to five years from the date of issuance. The Company's Chief Operating Officer, a related party, participated in the Private Placement by purchasing 141,453 shares of common stock and a warrant to purchase 35,363 shares of common stock for an aggregate purchase price of $0.5 million. Issuance costs of $0.3 million were offset against equity as a reduction from gross proceeds. At the close of the Private Placement, the estimated fair values of the common stock and warrants issued were $22.9 million and $2.6 million, respectively. In December 2016, certain holders of these warrants exercised warrants to purchase 707,269 shares of common stock, and after giving effect to net exercises, upon such exercises the Company issued an aggregate of 610,490 shares of common stock, with an estimated fair value at the time of exercise of $8.3 million. The Company recorded a charge of $7.4 million, for the increase in the estimated fair value, in the consolidated statements of operations, for the year ended December 31, 2016. At December 31, 2016, the Company estimated the fair value of the remaining warrants outstanding to be $13.9 million and recorded a charge of $12.2 million, for the change in the estimated fair value, in the consolidated statements of operations, for the year ended December 31, 2016. As of December 31, 2016, the following warrants to purchase shares of common stock were outstanding and exercisable: Warrant Holder Issue Date In Connection With Warrant to Purchase Shares Exercise Price Expiration Date Oxford Finance LLC 4/30/2012 Loan agreement Common stock 11,676 $ 11.99 11/1/2021 SVB 4/30/2012 Loan agreement Common stock 8,340 $ 11.99 11/1/2021 Oxford Finance LLC 11/1/2011 Loan agreement Common stock 5,838 $ 11.99 11/1/2021 SVB 11/1/2011 Loan agreement Common stock 4,170 $ 11.99 11/1/2021 Growth Equity Opportunities Fund IV, LLC 6/3/2016 Private Placement Common stock 1,178,782 $ 3.66 6/3/2021 DAFNA Lifescience, L.P. 6/3/2016 Private Placement Common stock 47,151 $ 3.66 6/3/2021 DAFNA Lifescience Select, L.P. 6/3/2016 Private Placement Common stock 31,434 $ 3.66 6/3/2021 Blake A. Wise Trust 6/3/2016 Private Placement Common stock 35,363 $ 3.66 6/3/2021 1,322,754 In February 2017, certain holders of these warrants exercised warrants to purchase 91,095 shares of common stock, and after giving effect to net exercises, upon such exercises the Company issued an aggregate of 84,481 shares of common stock and received $0.3 million in proceeds.

Equity Incentive Plans

Equity Incentive Plans	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	10. Equity Incentive Plans 2014 Plan In February 2014, the Company’s stockholders approved the 2014 Equity Incentive Award Plan (the “2014 Plan”), which became effective as of March 11, 2014. Under the 2014 Plan, the Company may grant incentive stock options (“ISOs”), nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards (“RSUs”) and other stock-based awards for the purchase of common stock. Effective January 1, 2016, the compensation committee of the board of directors approved an evergreen increase of 735,808 shares of common stock that may be granted in accordance with the terms of the 2014 Plan. As of December 31, 2016, 621,286 shares were available for future issuance under the 2014 Plan. Under the 2014 Plan, the terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2014 Plan. Options granted by the Company typically vest over a four year period and the exercise price may not be less than fair market value on the date of grant. Certain of the options are subject to acceleration of vesting in the event of certain change of control transactions. Options granted under the 2014 Plan expire no later than 10 years from the date of grant. 2014 Employment Commencement Incentive Plan In December 2014, the Company adopted a 2014 Employment Commencement Incentive Plan (the “Inducement Plan”). The Inducement Plan is designed to comply with the inducement exemption contained in Nasdaq’s Rule 5635(c)(4), which provides for the grant of non-qualified stock options, restricted stock units, restricted stock awards, performance awards, dividend equivalents, deferred stock awards, deferred stock units, stock payment and stock appreciation rights to a person not previously an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to the individual’s entering into employment with the Company. As of December 31, 2016, a total of 1,150,000 shares of common stock have been authorized under the Inducement Plan, including the additional 500,000 shares that became available resulting from an amendment adopted by the board of directors as of March 17, 2016. As of December 31, 2016, 18,088 shares were available for issuance under the Inducement Plan. 2014 Employee Stock Purchase Plan In February 2014, the Company’s stockholders approved the 2014 Employee Stock Purchase Plan (the “ESPP”), which became effective as of March 11, 2014. The number of shares of common stock initially reserved for issuance under the ESPP was 145,454 shares. Effective January 1, 2016, the board of directors approved an evergreen increase of 183,952 shares that may be granted in accordance with the terms of the ESPP. As of December 31, 2016, 225,261 shares of common stock have been issued to employees participating in the ESPP, and 283,216 shares were available for issuance under the ESPP. Amended and Restated 2003 Stock Plan The Company’s Amended and Restated 2003 Stock Plan, referred to herein as the 2003 Plan, provided for the granting of incentive and non-statutory stock options to employees, directors and consultants at the discretion of the board of directors. The Company granted options under its 2003 Plan until January 2014 when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding under the 2003 Plan. Options granted under the 2003 Plan expire no later than 10 years from the date of grant. Options granted under the 2003 Plan vest over periods determined by the board of directors, generally over four years. In connection with the Board of Directors and stockholders approval of the 2014 Plan, all remaining shares available for future awards under the 2003 Plan were transferred to the 2014 Plan, and the 2003 Plan was terminated as to future awards. As of December 31, 2016, a total of 877,234 shares of common stock are subject to options outstanding under the 2003 plan, which shares will become available under the 2014 Plan to the extent the options are forfeited or lapse unexercised. Total stock-based compensation recognized in the Company’s consolidated statements of operations for the years ended December 31, 2016, 2015 and 2014, was classified as follows (in thousands): Year Ended December 31, 2016 2015 2014 Research and development $ 2,165 $ 1,404 $ 570 General and administrative 1,682 1,579 1,480 Total $ 3,847 $ 2,983 $ 2,050 A summary of stock option activity is as follows: Outstanding Options Shares Available for grant Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Balance, January 1, 2014 127,277 1,405,550 $ 5.68 Additional shares reserved 1,190,908 — Shares reserved for the 2014 Employment Commencement Incentive Plan 650,000 — Options granted (876,163 ) 876,163 $ 10.15 RSUs granted (168,200 ) — Options exercised — (208,693 ) $ 3.38 $ 1,704 Options forfeited 187,648 (187,648 ) $ 6.29 Balance, December 31, 2014 1,111,470 1,885,372 $ 7.95 Additional shares reserved 716,285 — Options granted (929,100 ) 929,100 $ 7.95 Options exercised — (190,128 ) $ 5.54 $ 923 Options forfeited 237,007 (237,007 ) $ 10.22 RSUs granted (291,525 ) — RSUs cancelled 49,325 — Balance, December 31, 2015 893,462 2,387,337 $ 7.92 $ 293 Additional shares reserved 1,235,808 — Options granted (1,477,600 ) 1,477,600 $ 4.10 Options exercised — (14,190 ) $ 4.59 $ 89 Options forfeited 310,454 (310,454 ) $ 8.19 RSUs granted (380,500 ) — RSUs cancelled 57,750 — Balance, December 31, 2016 639,374 3,540,293 $ 6.31 7.98 $ 23,837 At December 31, 2016: Vested and exercisable 1,315,306 $ 7.41 6.71 $ 7,441 Vested and expected to vest 3,453,530 $ 6.27 8.02 $ 23,408 The following table summarizes information about stock options outstanding as of December 31, 2016: Options Outstanding Vested and Exercisable Exercise Price Number of Options Weighted-Average Remaining Contractual Life (in Years) Number of Options Weighted-Average Exercise Price $2.64 - $3.41 1,137 1.13 1,137 $ 2.69 $3.65 504,153 9.16 64,101 $ 3.65 $3.68 - $4.34 605,058 9.36 12,429 $ 4.27 $4.44 - $4.84 362,041 7.52 199,867 $ 4.73 $4.86 - $5.86 458,062 9.1 115,516 $ 5.73 $6.60 - $6.99 447,807 6.25 297,277 $ 6.91 $7.08 - $8.04 546,877 6.5 294,696 $ 7.53 $9.21 - $10.44 409,489 7.67 205,140 $ 9.65 $11.78 - $12.22 152,659 7.88 88,818 $ 11.93 $14.89 53,010 7.17 36,325 $ 14.89 3,540,293 7.98 1,315,306 $ 7.41 Stock Options Granted to Employees and Non-Employee Directors During the years ended December 31, 2016, 2015 and 2014, the Company granted stock options to employees and directors to purchase 1,477,600, 929,100 and 876,163 shares, respectively, of common stock under the stock plans with a weighted-average estimated grant-date fair value of $4.10, $5.02 and $6.41 per share, respectively. As of December 31, 2016, there were unrecognized compensation costs of $6,695,000 related to outstanding employee and non-employee director stock options, which are expected to be recognized over a weighted-average period of 2.96 years. The Company estimated the fair value of stock options using the Black-Scholes option valuation model for options with time-based vesting terms. The Black-Scholes model requires the input of subjective assumptions, including (a) the expected term of the award, (b) the expected stock price volatility, (c) the risk-free interest rate and (d) expected dividends. The estimated fair value of these employee stock options is being amortized on a straight-line basis over the requisite service period of the awards. The fair value of the employee stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2016 2015 2014 Expected term 5.3–6.0 years 5.4–6.0 years 5.3–6.1 years Expected volatility 67%–74% 65%–75% 67%–77% Risk-free interest rate 1.1%–1.9% 1.5%–1.9% 1.7%–2.0% Expected dividend yield —% —% —% The Company has opted to use the “simplified method” for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. Prior to the Company's IPO in March 2014, due to the Company’s limited operating history and company specific stock price volatility data, the Company based its estimate of expected volatility on the historical price volatility of a group of similar companies that are publicly traded. Beginning in 2014 the Company began to include the historical price volatility of its own stock, along with data for the group of similar companies, to estimate expected volatility. When selecting these public companies to use in estimating its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, stages of clinical development, risk profiles, position within the industry and with historical share price information sufficient to meet the expected life of the stock-based awards. The risk-free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of the Company’s stock options. The expected dividend assumption is based on the Company’s history of not paying dividends and its expectation that it will not declare dividends for the foreseeable future. Stock Options Granted to Non-Employees During the year ended December 31, 2016, the Company granted to a non-employee an option to purchase 15,000 shares of common stock. The Company did not grant stock options to non-employees during the years ended December 31, 2015 and 2014. The Company recorded non-employees stock-based compensation expense of approximately $71,000 for the year ended December 31, 2016. The Company measures the estimated fair value of the award for each period until the award is fully vested. The fair value of options granted to non-employees during the year ended December 31, 2016 was estimated using Black-Scholes with the following assumptions: Year Ended December 31, 2016 Expected term 0.8–1.0 years Expected volatility 63%–125% Risk-free interest rate 0.6%–0.9% Expected dividend yield —% Restricted Stock Units Granted to Employees and Non-Employee Directors During the years ended December 31, 2016, 2015 and 2014, the Company granted restricted stock units (“RSUs”) to employees to purchase 380,500, 291,525 and 168,200 shares of common stock, respectively, under the stock plans with a weighted-average estimated grant-date fair value of $4.01 $7.76 and $9.33 per share, respectively. RSUs generally vest annually over a 4-year service period and vesting is contingent on continued service. As of December 31, 2016, there were unrecognized compensation costs of $2,853,000 related to outstanding RSUs, which are expected to be recognized over a weighted-average period of 2.78 years. A summary of RSU activity is as follows: RSU Awards Outstanding Number of Shares Weighted-Average Grant Date Fair Market Value Aggregate Intrinsic Value (in thousands) Balance, December 31, 2013 — — — RSUs granted 168,200 $ 9.33 Balance, December 31, 2014 168,200 $ 9.33 $ 2,195 RSUs granted 291,525 $ 7.76 RSUs released (38,376 ) $ 9.42 RSUs cancelled (49,325 ) $ 9.80 Balance, December 31, 2015 372,024 $ 8.02 $ 2,135 RSUs granted 380,500 $ 4.01 RSUs released (89,722 ) $ 8.22 RSUs cancelled (57,750 ) $ 6.71 Balance, December 31, 2016 605,052 $ 5.60 $ 7,878 Stock Options and Restricted Stock Units Granted to Employees that Contain Performance Conditions During the years ended December 31, 2016, 2015 and 2014, the Company granted options to purchase an aggregate of 354,250, zero and 168,977 shares of common stock and 59,925, zero and zero RSUs that vest upon the achievement of market-based common stock price targets. The fair value was estimated at the grant date using a Monte-Carlo simulation model (“Monte-Carlo”), which requires the use of a range of assumptions. The expected life assumption is not used in the Monte-Carlo simulation model, but the output of the model indicates an expected life. The associated stock-based compensation expense is being recognized on a straight-line basis over the implicit service period (expected time to vest) derived from that simulation model. The fair value of awards granted to non-employees was estimated using Monte-Carlo with the following assumptions: Year Ended December 31, 2016 2014 Expected term 2.2–6.0 years 2.9–6.3 years Expected volatility 70% 60–70% Risk-free interest rate 1.4%–2.3% 2.5%–2.8% Expected dividend yield —% —%

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 31, 2016, 2015 and 2014 is as follows: Year Ended December 31, 2016 2015 2014 Statutory tax rate 34.00 % 34.00 % 34.00 % State taxes, net of federal benefits 0.96 % -3.62 % 5.04 % Stock-based compensation -0.62 % -1.20 % -0.76 % Credits 1.46 % 3.30 % 3.21 % Other -0.10 % -0.54 % -1.74 % Valuation allowance -26.22 % -31.94 % -39.75 % Warrant Valuation -9.48 % 0.00 % 0.00 % Effective tax rate 0.00 % 0.00 % 0.00 % The tax effects of temporary differences and carryforwards that give rise to the Company’s deferred tax assets are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Net operating loss carry forwards $ 71,858 $ 57,558 Research and development credit 10,969 8,531 Intangible assets 1,653 1,994 Depreciation 191 195 Temporary differences 4,682 2,396 Gross Deferred tax assets 89,353 70,674 Less: valuation allowance (89,353 ) (70,674 ) Net deferred tax assets $ — $ — Realization of the deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The net valuation allowance increased by $18,679,000 and $7,975,000 during the years ended December 31, 2016 and 2015, respectively. The Company had federal and state net operating loss carryforwards of approximately $196,669,000 and $90,810,000, respectively, at December 31, 2016. The federal and state net operating loss carryforwards are available to reduce future taxable income, if any. If not utilized, the federal and state operating loss carryforwards will begin to expire in various amounts beginning 2023 and 2017, respectively. The Company also had federal and state research and development credit carryforwards of approximately $8,965,000 and $5,186,000, respectively, at December 31, 2016. The federal research and development credits will begin to expire in 2025. The state research and development credits can be carried forward indefinitely. Utilization of the net operating loss and research and development credits carryforwards may be subject to an annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss and research and development credits before utilization. The Company files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. The Company is subject to U.S. federal and state income tax examinations by tax authorities for tax years from 2003 due to net operating losses and tax credits that are being carried forward for tax purposes. The Company recognizes the financial statements effects of a tax position when it is more likely than not, based on technical merits, that the position will be sustained upon examination. A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): December 31, 2016 2015 2014 Balance at beginning of year $ 957 $ — $ — Increase related to current year tax provision 240 162 — Increase related to prior year tax provision — 795 — Balance at end of year $ 1,197 $ 957 $ — The unrecognized tax benefits, if recognized and in absence of full valuation allowance, would impact the income tax provision by $1,024,000, $820,000 and $678,000 as of December 31, 2016, 2015 and 2014. Given the Company’s valuation allowance, the uncertain tax positions would not impact the effective tax rates. The Company has elected to include interest and penalties as a component of tax expense. There was no interest or penalties accrued related to uncertain tax positions as of December 31, 2016.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plan	12. Employee Benefit Plan In 2003, the Company adopted a 401(k) plan for its employees whereby eligible employees may contribute up to 100% of their compensation, on a pretax basis, subject to the maximum amount permitted by the Internal Revenue Code. In December 2010, the Company approved a plan to provide matching contributions equal to 50% of employees’ contributions, up to 6% of annual earnings, starting in January 2011. In December 2015, the Company has changed the plan to increase its 401(k) match to 50% of employees' contributions, up to 8% of annual earnings, starting in January 2016. The Company's contributions were $469,000, $255,000 and $184,000 for the years ended December 31, 2016, 2015 and 2014, respectively.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related-Party Transactions	13. Related-Party Transactions In 2016, the Company sold 7,999,996 shares of its common stock and warrants to purchase 1,999,999 shares of its common stock pursuant to the Purchase Agreement for aggregate gross proceeds of $25.4 million in the Private Placement. The warrants have an exercise price of $3.66 per share and are exercisable up to five years from the date of issuance. The Company's Chief Operating Officer, a related party, participated in the Private Placement by purchasing 141,453 shares of common stock and a warrant to purchase 35,363 shares of common stock for an aggregate purchase price of $0.5 million. For further detail of the warrants issued in connection with the Private Placement, refer to Note 9.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events In March 2017, the Company entered into a commercial validation and manufacturing agreement (the “Manufacturing Agreement”) with Hovione Limited (“Hovione”). Under the Manufacturing Agreement, Hovione has agreed to complete the validation program to validate and scale up the Company’s technology to manufacture the active pharmaceutical ingredient for plazomicin (the “Product”) and supply the Product to the Company. The Manufacturing Agreement has an initial term of seven years after the first delivery of the Product. Subject to the successful completion of the validation program and the Company’s launch of plazomicin, the Company has agreed to purchase a minimum quantity of the Product from Hovione depending on the Company’s requirements and the period of time following approval by the FDA. For the first three years following approval of plazomicin by the FDA, the Company is required to purchase at least 80% of its required quantity from Hovione. Following the initial three years after FDA approval, the Company is required to purchase between 40% and 66% of its required quantity from Hovione, depending on the amounts required during any such fiscal year. Contingent upon FDA’s approval of plazomicin, the Company has minimum annual purchase commitments from Hovione, beginning in 2020 through 2024.

Selected Unaudited Quarterly Fi

Selected Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Unaudited Quarterly Financial Data	15. Selected Unaudited Quarterly Financial Data The following tables show a summary of the Company’s unaudited quarterly financial data for each of the four quarters of 2016, 2015 and 2014 (in thousands, except per share amounts): Three Months Ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Contract revenue 10,734 16,046 9,144 5,849 Operating expenses 22,796 24,996 25,659 17,670 Other income (expense), net (17,662 ) (2,088 ) (1,753 ) (376 ) Net loss (29,724 ) (11,038 ) (18,268 ) (12,197 ) Basic and diluted net loss per common share (1.04 ) (0.41 ) (0.87 ) (0.66 ) Three Months Ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Contract revenue 4,664 4,476 12,041 4,880 Operating expenses 15,548 13,006 12,970 11,110 Other income (expense), net (382 ) (232 ) 43 51 Net loss (11,266 ) (8,762 ) (886 ) (6,179 ) Basic and diluted net loss per common share (0.61 ) (0.48 ) (0.05 ) (0.34 ) Three Months Ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Contract revenue 4,259 4,520 5,203 5,988 Operating expenses 9,140 12,853 8,541 9,222 Other income and expense, net 27 21 (217 ) (221 ) Net loss (4,854 ) (8,312 ) (3,555 ) (3,455 ) Basic and diluted net loss per common share (0.27 ) (0.47 ) (0.20 ) (1.00 ) (1) Basic and diluted net loss per common share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Reclassifications	Reclassifications The change in derivative liability for the year ended December 31, 2015 has been reclassified to be included in the change in warrant and derivative liabilities to conform to the current year’s presentation. Such reclassifications did not impact the Company’s net loss or financial position.
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include the consolidated accounts of the Company and its subsidiary. Intercompany accounts and transactions have been eliminated in consolidation. During 2012, the Company established a wholly owned foreign subsidiary in the United Kingdom. There have been no significant activities for this entity during the fiscal years ended December 31, 2016, 2015 and 2014. In March 2014, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 6,900,000 shares of common stock, which includes 900,000 shares issued pursuant to the over-allotment option granted to its underwriters, and received net proceeds of approximately $73.9 million, after deducting underwriting discounts, commissions and offering expenses. In connection with the completion of the Company's IPO, all shares of convertible preferred stock converted into 10,386,894 shares of common stock and all of the Company's convertible preferred stock warrants were converted into warrants to purchase common stock. On April 7, 2015, the Company filed a Registration Statement on Form S-3, declared effective by the SEC on April 21, 2015, covering the offering of up to $150.0 million of common stock, preferred stock, debt securities, warrants, purchase contracts and/or units. This Registration Statement included a prospectus covering the offering, issuance and sale of up to $30.0 million of shares of the Company’s common stock from time to time in an “at-the-market” (“ATM”) equity offering pursuant to a sales agreement with Cowen and Company, LLC. As of December 31, 2016, the Company had sold 1,105,549 shares pursuant to its ATM equity offering program at a weighted-average price of $4.82 per share for aggregate offering proceeds of $5.3 million and aggregate net proceeds of $5.1 million, after deducting the sales commissions and offering expenses. On June 3, 2016, the Company sold 7,999,996 shares of its common stock and warrants to purchase 1,999,999 shares of its common stock pursuant to Securities Purchase Agreement (the "Purchase Agreement") for aggregate gross proceeds of $25.4 million and aggregate net proceeds of $25.1 million, after deducting the issuance costs, in connection with a private placement financing transaction (the "Private Placement"). The warrants have an exercise price of $3.66 per share and are exercisable up to five years from the date of issuance. On December 19, 2016, the Company completed an underwritten public offering of common stock made under a prospectus supplement and related prospectus pursuant to the Shelf Registration Statement. This offering resulted in the sale of 7,475,000 shares, at a price of $13.50 per share, including the full exercise of the underwriter’s option to purchase an additional 975,000 shares of common stock. The Company received net proceeds from the offering of $94.6 million, after deducting the underwriting discounts and commissions and estimated offering expenses. The Company has incurred losses and negative cash flows from operations every year since its inception. As of December 31, 2016, the Company had unrestricted cash, cash equivalents and short-term investments of approximately $145.9 million and an accumulated deficit of approximately $247.2 million. Management expects that, based on its current operating plans, the Company’s existing cash, cash equivalents and short-term investments as of December 31, 2016, combined with the committed funds from the BARDA and NIAID contracts, will be sufficient to fund its current planned operations for at least the next twelve months from the issuance of this report. Management plans to raise additional funds through equity or debt financing arrangements, government contracts, and/or third party collaboration funding in the future to fund its operations, including the commercial launch of plazomicin. However, there can be no assurance that such funding sources will be available at terms acceptable to the Company or at all. If the Company is unable to raise additional funding to meet its working capital needs, it will be forced to delay or reduce the scope of its research programs and/or limit or cease its operations. The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern.
Use of Estimates	Use of Estimates The accompanying financial statements have been prepared in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosures of contingent liabilities. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of derivative and warrant liabilities, common stock and stock-based awards and income taxes. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments, including cash and cash equivalents, contracts receivable, prepaid and other current assets, accounts payable, accrued liabilities, and other current liabilities approximate fair value due to their short-term maturities. Short-term investments consist of available-for-sale securities as of December 31, 2016 and are carried at fair value. Based upon the borrowing rates currently available to the Company for loans with similar terms, the Company believes the carrying amounts of the loan payable and the derivative liability also represent fair values.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents include only securities having an original maturity of three months or less at the time of purchase. As of December 31, 2016 and 2015, cash and cash equivalents consisted of bank deposits, cash, and investments in money market funds.
Short-term Investments	Short-term Investments Short-term investments consist of debt securities with maturities greater than three months, but less than one year from the date of acquisition, and are classified as available for sale. Short-term investments are carried at fair value. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of net unrealized losses on available-for-sale securities in the Company's consolidated statements of comprehensive loss. The amortized cost of debt securities reflects amortization of purchase premiums and accretion of purchase discounts to date, which is included in interest income. The Company reviews all of its marketable securities on a regular basis to evaluate whether any security has experienced an other-than-temporary decline in fair value.
Restricted Cash	Restricted Cash At December 31, 2016 and December 31, 2015, the Company had restricted cash of $377,000 and $127,000. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): Year Ended December 31, 2016 2015 2014 Cash and cash equivalents $ 118,964 $ 20,287 $ 18,881 Restricted cash, current 127 - - Restricted cash, non current 250 127 127 Total cash, cash equivalents, and restricted cash $ 119,341 $ 20,414 $ 19,008 The restricted cash, which consists of money market accounts with one of the Company’s financial institutions, serves as collateral for the letters of credit provided as security deposits under the Company’s facility leases. As of December 31, 2016, $127,000 of restricted cash is classified as current assets and relates to the current facility lease that expires on April 14, 2017.
Segment Reporting	Segment Reporting 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 in making decisions regarding resource allocation and assessing performance. The Company has one operating segment.
Customer Concentration	Customer Concentration For the years ended December 31, 2016, 2015 and 2014, all of the Company’s revenue has been generated solely from funding pursuant to U.S. government contracts, and accordingly all contracts receivable relate to funding from U.S. government contracts.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a significant concentration of credit risk consist of cash, cash equivalents and short-term investments. Cash and cash equivalents are deposited in checking and money market accounts at one financial institution, which at times, may exceed federally insured limits. Management believes that the financial institution is financially sound, and, accordingly, minimal credit risk exists with respect to this financial institution. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of default by the institutions holding its cash and cash equivalents or issuing the debt securities. As of December 31, 2016, the Company has not experienced any credit losses in such accounts or investments.
Contracts Receivable	Contracts Receivable Contracts receivable represent amounts owed to the Company under certain government contracts. The Company had no amounts reserved for doubtful accounts as of December 31, 2016 and 2015, as the Company expects full collection of the receivable balances.
Property and Equipment, Net	Property and Equipment, Net Property and equipment consists of office equipment, laboratory equipment, and leasehold improvements and is stated at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized over their estimated useful lives or the remaining lease term, whichever is shorter. Maintenance and repair costs are recorded as a component of operating expenses in the Company’s consolidated statement of operations when incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment charge is determined based upon the excess of the carrying value of the asset over its estimated fair value, with estimated fair value determined based upon an estimate of discounted future cash flows or other appropriate measures of estimated fair value. For the years ended December 31, 2016, 2015 and 2014, the Company did not have any impairment charges.
Convertible Preferred Stock Warrant Liabilities	Convertible Preferred Stock Warrant Liabilities The Company accounted for its Series A and Series C convertible preferred stock warrants as freestanding warrants for shares that are puttable or redeemable. At December 31, 2013, these warrants were classified as liabilities on the consolidated balance sheet at their estimated fair value. At the end of each reporting period, changes in estimated fair value during the period were recorded as a component of other income, net. At the time of the IPO, the warrants to purchase preferred stock were converted into warrants to purchase common stock, which are no longer subject to remeasurement, and the preferred stock warrant liability was reclassified to additional paid-in capital at its then fair value.
Warrant Liability	Warrant Liability On June 3, 2016, the Company issued warrants to purchase 1,999,999 shares of its common stock in connection with the Private Placement. Each warrant has an exercise price of $3.66 per share and is exercisable for five years from the date of issuance. The Company accounts for these warrants as a liability instrument measured at estimated fair value. The initial fair value of the warrants was determined using a calibration model that involved using the Black-Scholes Pricing Model ("Black-Scholes"), which requires inputs such as the risk-free interest rate, expected share price volatility, underlying price per share of the Company's common stock and remaining term of the warrants. The warrants are subject to remeasurement at each balance sheet date, using Black-Scholes, with any changes in the fair value of the outstanding warrants recognized in the condensed consolidated statements of operations.
Stock-Based Compensation	Stock-Based Compensation The Company measures and recognizes the compensation expense for all stock-based awards made to employees and directors, including employee stock options, stock grants and employee stock purchases related to the Employee Stock Purchase Plan (“ESPP”) based on estimated fair values. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock option and ESPP awards with time-based vesting terms. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of complex and subjective variables. The fair value of restricted stock unit (“RSU”) awards with time-based vesting terms is based on the grant date share price. The Company recognizes stock-based compensation cost over the award’s requisite service period on a straight-line basis for time-based awards and on a graded basis for awards that are contingent on the achievement of market-based conditions. The Company records stock-based compensation expense, net of the estimated impact of forfeited awards. As such, the Company recognizes stock-based compensation expense only for those stock-based awards that are expected to vest over their requisite service period, based on the vesting provisions of the individual underlying grants. During 2016 and 2014, the Company issued stock-based option awards with market-based conditions that vest upon achievement of certain market price thresholds of the Company’s common stock. The estimated fair value for market-based stock option awards is determined using a lattice valuation model with a Monte-Carlo simulation. The model takes into consideration the historical volatility of the Company’s stock and the risk-free interest rate at the date of grant. In addition, the model is used to estimate the derived service period for the awards. The derived service period is the estimated period of time that would be required to satisfy the market condition, assuming the market condition will be satisfied. Stock-based compensation expense is recognized over the implicit service period derived from the Monte-Carlo simulation model, as applicable, but is accelerated if the market condition is achieved earlier than estimated. For non-employee stock-based awards, the measurement date on which the estimated fair value of the stock-based award is calculated is equal to the earlier of (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. The Company recognizes stock-based compensation expense for the estimated fair value of the vested portion of non-employee awards.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when: (i) evidence of an arrangement exists, (ii) fees are fixed or determinable, (iii) services have been delivered, and (iv) collectability is reasonably assured. The Company currently generates revenue entirely from government contracts. Government contracts provide the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from government contracts is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the government contracts have been met. Costs of contract revenue are recorded as a component of operating expenses in the Company’s consolidated statements of operations. Funds received from third parties under contract arrangements are recorded as revenue if the Company is deemed to be the principal participant in the contract arrangements because the activities under the contracts are part of the Company’s development programs. If the Company is not the principal participant, the funds from contracts are recorded as a reduction to research and development expense. Contracts funds received are not refundable and are recognized when the related qualified research and development costs are incurred and when there is reasonable assurance that the funds will be received. Funds received in advance are recorded as deferred revenue. Management has determined that the Company is the principal participant under the Company’s government contract arrangements, and accordingly, the Company records amounts earned under the arrangements as revenue.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses include certain payroll and personnel expenses, laboratory supplies, consulting costs, external contract research and development expenses, and allocated overhead, including rent, equipment depreciation, and utilities and relate to both Company-sponsored programs as well as costs incurred pursuant to collaboration agreements and government contracts. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and recognized as an expense as the goods are delivered or the related services are performed. For certain research and development services where the Company has not yet been invoiced or otherwise notified of actual cost from the third-party contracted service providers, the Company is required to estimate the extent of the services that have been performed on the Company’s behalf and the associated costs incurred at each reporting period. The majority of the service providers invoice the Company monthly in arrears for services performed. The Company make estimates of the accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to the Company at that time. The Company periodically confirm the accuracy of the estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include services from: • CROs and other service providers in connection with clinical studies; • contract manufacturers in connection with the production of clinical trial materials; and • vendors in connection with preclinical development activities. The Company bases the expenses related to preclinical studies and clinical trials on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage such studies and trials on the Company’s behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows and expense recognition. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing service fees, the Company estimates the time period over which these services will be performed and the level of effort to be expended and costs to be incurred during each reporting period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts the accrual accordingly. The Company’s estimation of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting changes in estimates in any particular period. To date, there have been no material adjustments from the Company’s estimates to the amount actually incurred.
Leases	Leases The Company has entered into lease agreements for its laboratory and office facilities. These leases qualify as and are accounted for as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease and, accordingly, the Company records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Incentives granted under the Company’s facilities leases, including allowances to fund leasehold improvements and rent holidays, are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease.
Income Taxes	Income Taxes The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company assesses the need for a valuation allowance against the Company’s deferred income tax assets by considering both positive and negative evidence related to whether it is more likely than not that the deferred income tax assets will be realized. In evaluating its ability to recover the deferred income tax assets within the jurisdiction from which they arise, the Company considered all available positive and negative evidence, including scheduled reversals of deferred income tax liabilities, projected future taxable income, tax-planning strategies, and results of recent operations. Due to the Company’s considerations, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits. The tax benefit recognized in the financial statements for a particular tax position is the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company's policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense.
Net Loss and Per Share	Net Loss and Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per common share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common share equivalents outstanding during the period. Because the Company has reported a net loss for the years ended December 31, 2016, 2015 and 2014, diluted net loss per common share is the same as basic net loss per common share for those periods. Effective as of the completion of the IPO, all of the Company’s preferred stock was converted to common stock. For purposes of calculating net loss per common share for the year ended December 31, 2014, the preferred stock converted to common stock was included in the net loss per common share calculation on a post-conversion basis based on the conversion date. The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2016, 2015 and 2014 (in thousands, except share and per share amounts): Year Ended December 31, 2016 2015 2014 Net loss $ (71,227 ) $ (27,093 ) $ (20,176 ) Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share 23,707,063 18,147,986 14,210,098 Basic and diluted net loss per common share $ (3.00 ) $ (1.49 ) $ (1.42 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an anti-dilutive impact due to losses reported (in common stock equivalent shares): December 31, 2016 2015 2014 Options to purchase common stock 3,540,293 2,387,337 1,885,372 Restricted stock units 605,052 372,024 168,200 Warrants to purchase common stock 1,322,754 30,024 40,454 Warrants outstanding as of December 31, 2016 have a weighted-average exercise price of $3.85.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern Going Concern In November 2015, the FASB issued ASU No. 2015-17, Income Taxes Balance Sheet Classification of Deferred Taxes In February 2016, the FASB issued ASU No. 2016-02, Leases In March 2016, the FASB issued ASU No. 2016-06, Derivatives and Hedging Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued ASU No 2016-09, Compensation - Stock Compensation Improvements to Employee Share-Based Payment Accounting In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most current revenue recognition guidance. This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company has not yet finalized its preliminary assessment and conclusions on how the adoption of this ASU will affect its current policies related to revenue recognition. The Company will adopt the new revenue standard on January 1, 2018, and through the remainder of 2017, will continue to assess the potential impact of adopting this new standard on any current, new or significantly modified customer contracts. In subsequent quarters, the Company will finalize its selection of transition methods, and complete its evaluation of additional disclosures that may be required upon adoption of the new standard. In November, 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows Restricted Cash

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): Year Ended December 31, 2016 2015 2014 Cash and cash equivalents $ 118,964 $ 20,287 $ 18,881 Restricted cash, current 127 - - Restricted cash, non current 250 127 127 Total cash, cash equivalents, and restricted cash $ 119,341 $ 20,414 $ 19,008
Schedule of Weighted Average Number of Shares	The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2016, 2015 and 2014 (in thousands, except share and per share amounts): Year Ended December 31, 2016 2015 2014 Net loss $ (71,227 ) $ (27,093 ) $ (20,176 ) Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share 23,707,063 18,147,986 14,210,098 Basic and diluted net loss per common share $ (3.00 ) $ (1.49 ) $ (1.42 )
Schedule of Potentially Dilutive Securities Outstanding Excluded from the Computations of Diluted Weighted-Average Shares Outstanding	The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an anti-dilutive impact due to losses reported (in common stock equivalent shares): December 31, 2016 2015 2014 Options to purchase common stock 3,540,293 2,387,337 1,885,372 Restricted stock units 605,052 372,024 168,200 Warrants to purchase common stock 1,322,754 30,024 40,454

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured and Recognized at Fair Value	Financial assets and liabilities measured and recognized at fair value on a recurring basis were as follows (in thousands): As of December 31, 2016: December 31, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Assets Cash $ 3,728 $ — $ — $ 3,728 Level 1: Restricted cash 377 — — 377 Money market funds 115,236 — — 115,236 Subtotal 115,613 — — 115,613 Level 2: Corporate debt securities 12,969 — (7 ) 12,962 Commercial paper 13,950 — — 13,950 Subtotal 26,919 — (7 ) 26,912 $ 146,260 $ — $ (7 ) $ 146,253 Reported as: Cash and cash equivalents $ 118,964 Short-term investments $ 26,912 Restricted cash $ 377 Liabilities, Level 3 Warrant Liability $ 13,874 Derivative Liability $ 602 Total $ 14,476 As of December 31, 2015: December 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Assets Cash $ 1,013 $ — $ — $ 1,013 Level 1: Restricted cash 127 — — 127 Money market funds 19,274 — — 19,274 Subtotal 19,401 — — 19,401 Level 2: Corporate debt securities 34,490 — (47 ) 34,443 Commercial paper 1,997 — — 1,997 US Treasury bills 2,005 — (1 ) 2,004 Subtotal 38,492 — (48 ) 38,444 Total $ 58,906 $ — $ (48 ) $ 58,858 Reported as: Cash and cash equivalents $ 20,287 Short-term investments $ 38,444 Restricted cash $ 127 Liabilities Level 3: Derivative liability $ 375
Schedule of Assumptions Used	The estimated fair values of the warrants were determined using Black-Scholes with the following assumptions, during the year ended December 31, 2016: Year Ended December 31, 2016 Expected volatility 60% – 80% Expected term 4.4 – 5.0 years Risk-free interest rate 1.0% – 1.9% Dividend yield 0%
Activity in Preferred Stock Warrant Liability	The following table provides a summary of changes in the estimated fair value of the Company’s liabilities measured at estimated fair value using significant Level 3 inputs for the years ended 2016, 2015 and 2014 (in thousands): Estimated Fair Value of Convertible Preferred Stock Warrant Liabilities Estimated Fair Value of Derivative Liability Estimated Fair Value of Warrant Liability Balance of Level 3 Liabilities at December 31, 2013 $ 244 $ — $ — Change in estimated fair value of convertible preferred stock warrant liabilities 42 — — Reclassification of warrant liability to additional paid-in-capital upon conversion of warrant to purchase convertible preferred stock to warrant to purchase common stock (286 ) — — Balance of Level 3 Liabilities at December 31, 2014 — — — Estimated fair value of derivative liability issued — 356 — Change in estimated fair value of derivative liability — 19 — Balance of Level 3 Liabilities at December 31, 2015 — 375 — Estimated fair value of warrants issued — — 2,579 Change in estimated fair value of warrant liability — — 19,632 Reclassification of warrant liability to additional paid-in-capital upon exercise of warrants (8,337 ) Change in estimated fair value of derivative liability — 227 — Balance of Level 3 Liabilities at December 31, 2016 $ — $ 602 $ 13,874

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Schedule of Property and Equipment	Property and equipment, net consisted of the following (in thousands): December 31, 2016 2015 Office equipment $ 644 $ 1,144 Laboratory equipment 4,038 3,161 Leasehold improvements 1,072 1,072 Construction-in-progress 1,896 — 7,650 5,377 Less: accumulated depreciation and amortization $ (4,389 ) (4,472 ) Property and equipment, net $ 3,261 $ 905
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): December 31, 2016 2015 Accrued clinical and development expenses $ 3,681 $ 2,869 Payroll and related bonus expenses 4,941 1,615 Other 1,076 443 $ 9,698 $ 4,927

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	Future minimum lease payments under the operating leases as of December 31, 2016 are as follows (in thousands): Year-ended December 31, Amounts 2017 $ 1,103 2018 2,500 2019 2,890 2020 2,991 2021 3,098 Thereafter 19,717 Total minimum lease payments $ 32,299

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Schedule of Future Minimum Debt Obligation Payments	Future principal debt payments on the loan payable are as follows (in thousands): December 31, 2016 2017 $ 4,167 2018 12,500 2019 8,333 Total principal payments 25,000 Final fee due at maturity in 2019 2,000 Total principal and final fee payments 27,000 Unamortized discount and debt issuance costs (1,723 ) Less current portion (4,167 ) Loan payable, long term $ 21,110

Stockholders' Equity and Conv29

Stockholders' Equity and Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Schedule of Stockholders' Equity Note, Warrants or Rights	As of December 31, 2016, the following warrants to purchase shares of common stock were outstanding and exercisable: Warrant Holder Issue Date In Connection With Warrant to Purchase Shares Exercise Price Expiration Date Oxford Finance LLC 4/30/2012 Loan agreement Common stock 11,676 $ 11.99 11/1/2021 SVB 4/30/2012 Loan agreement Common stock 8,340 $ 11.99 11/1/2021 Oxford Finance LLC 11/1/2011 Loan agreement Common stock 5,838 $ 11.99 11/1/2021 SVB 11/1/2011 Loan agreement Common stock 4,170 $ 11.99 11/1/2021 Growth Equity Opportunities Fund IV, LLC 6/3/2016 Private Placement Common stock 1,178,782 $ 3.66 6/3/2021 DAFNA Lifescience, L.P. 6/3/2016 Private Placement Common stock 47,151 $ 3.66 6/3/2021 DAFNA Lifescience Select, L.P. 6/3/2016 Private Placement Common stock 31,434 $ 3.66 6/3/2021 Blake A. Wise Trust 6/3/2016 Private Placement Common stock 35,363 $ 3.66 6/3/2021 1,322,754

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule of Stock-based Compensation Expense for Stock Options Granted to Employees and Non-employees	Total stock-based compensation recognized in the Company’s consolidated statements of operations for the years ended December 31, 2016, 2015 and 2014, was classified as follows (in thousands): Year Ended December 31, 2016 2015 2014 Research and development $ 2,165 $ 1,404 $ 570 General and administrative 1,682 1,579 1,480 Total $ 3,847 $ 2,983 $ 2,050
Summary of Stock Option Activity	A summary of stock option activity is as follows: Outstanding Options Shares Available for grant Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Balance, January 1, 2014 127,277 1,405,550 $ 5.68 Additional shares reserved 1,190,908 — Shares reserved for the 2014 Employment Commencement Incentive Plan 650,000 — Options granted (876,163 ) 876,163 $ 10.15 RSUs granted (168,200 ) — Options exercised — (208,693 ) $ 3.38 $ 1,704 Options forfeited 187,648 (187,648 ) $ 6.29 Balance, December 31, 2014 1,111,470 1,885,372 $ 7.95 Additional shares reserved 716,285 — Options granted (929,100 ) 929,100 $ 7.95 Options exercised — (190,128 ) $ 5.54 $ 923 Options forfeited 237,007 (237,007 ) $ 10.22 RSUs granted (291,525 ) — RSUs cancelled 49,325 — Balance, December 31, 2015 893,462 2,387,337 $ 7.92 $ 293 Additional shares reserved 1,235,808 — Options granted (1,477,600 ) 1,477,600 $ 4.10 Options exercised — (14,190 ) $ 4.59 $ 89 Options forfeited 310,454 (310,454 ) $ 8.19 RSUs granted (380,500 ) — RSUs cancelled 57,750 — Balance, December 31, 2016 639,374 3,540,293 $ 6.31 7.98 $ 23,837 At December 31, 2016: Vested and exercisable 1,315,306 $ 7.41 6.71 $ 7,441 Vested and expected to vest 3,453,530 $ 6.27 8.02 $ 23,408
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	The following table summarizes information about stock options outstanding as of December 31, 2016: Options Outstanding Vested and Exercisable Exercise Price Number of Options Weighted-Average Remaining Contractual Life (in Years) Number of Options Weighted-Average Exercise Price $2.64 - $3.41 1,137 1.13 1,137 $ 2.69 $3.65 504,153 9.16 64,101 $ 3.65 $3.68 - $4.34 605,058 9.36 12,429 $ 4.27 $4.44 - $4.84 362,041 7.52 199,867 $ 4.73 $4.86 - $5.86 458,062 9.1 115,516 $ 5.73 $6.60 - $6.99 447,807 6.25 297,277 $ 6.91 $7.08 - $8.04 546,877 6.5 294,696 $ 7.53 $9.21 - $10.44 409,489 7.67 205,140 $ 9.65 $11.78 - $12.22 152,659 7.88 88,818 $ 11.93 $14.89 53,010 7.17 36,325 $ 14.89 3,540,293 7.98 1,315,306 $ 7.41
Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model	The fair value of the employee stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2016 2015 2014 Expected term 5.3–6.0 years 5.4–6.0 years 5.3–6.1 years Expected volatility 67%–74% 65%–75% 67%–77% Risk-free interest rate 1.1%–1.9% 1.5%–1.9% 1.7%–2.0% Expected dividend yield —% —% —%
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of RSU activity is as follows: RSU Awards Outstanding Number of Shares Weighted-Average Grant Date Fair Market Value Aggregate Intrinsic Value (in thousands) Balance, December 31, 2013 — — — RSUs granted 168,200 $ 9.33 Balance, December 31, 2014 168,200 $ 9.33 $ 2,195 RSUs granted 291,525 $ 7.76 RSUs released (38,376 ) $ 9.42 RSUs cancelled (49,325 ) $ 9.80 Balance, December 31, 2015 372,024 $ 8.02 $ 2,135 RSUs granted 380,500 $ 4.01 RSUs released (89,722 ) $ 8.22 RSUs cancelled (57,750 ) $ 6.71 Balance, December 31, 2016 605,052 $ 5.60 $ 7,878
Black Scholes
Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model	The fair value of options granted to non-employees during the year ended December 31, 2016 was estimated using Black-Scholes with the following assumptions: Year Ended December 31, 2016 Expected term 0.8–1.0 years Expected volatility 63%–125% Risk-free interest rate 0.6%–0.9% Expected dividend yield —%
Monte Carlo Simulation
Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model	The fair value of awards granted to non-employees was estimated using Monte-Carlo with the following assumptions: Year Ended December 31, 2016 2014 Expected term 2.2–6.0 years 2.9–6.3 years Expected volatility 70% 60–70% Risk-free interest rate 1.4%–2.3% 2.5%–2.8% Expected dividend yield —% —%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 31, 2016, 2015 and 2014 is as follows: Year Ended December 31, 2016 2015 2014 Statutory tax rate 34.00 % 34.00 % 34.00 % State taxes, net of federal benefits 0.96 % -3.62 % 5.04 % Stock-based compensation -0.62 % -1.20 % -0.76 % Credits 1.46 % 3.30 % 3.21 % Other -0.10 % -0.54 % -1.74 % Valuation allowance -26.22 % -31.94 % -39.75 % Warrant Valuation -9.48 % 0.00 % 0.00 % Effective tax rate 0.00 % 0.00 % 0.00 %
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences and carryforwards that give rise to the Company’s deferred tax assets are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Net operating loss carry forwards $ 71,858 $ 57,558 Research and development credit 10,969 8,531 Intangible assets 1,653 1,994 Depreciation 191 195 Temporary differences 4,682 2,396 Gross Deferred tax assets 89,353 70,674 Less: valuation allowance (89,353 ) (70,674 ) Net deferred tax assets $ — $ —
Summary of Unrecognized Tax Benefits	A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): December 31, 2016 2015 2014 Balance at beginning of year $ 957 $ — $ — Increase related to current year tax provision 240 162 — Increase related to prior year tax provision — 795 — Balance at end of year $ 1,197 $ 957 $ —

Selected Unaudited Quarterly 32

Selected Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following tables show a summary of the Company’s unaudited quarterly financial data for each of the four quarters of 2016, 2015 and 2014 (in thousands, except per share amounts): Three Months Ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Contract revenue 10,734 16,046 9,144 5,849 Operating expenses 22,796 24,996 25,659 17,670 Other income (expense), net (17,662 ) (2,088 ) (1,753 ) (376 ) Net loss (29,724 ) (11,038 ) (18,268 ) (12,197 ) Basic and diluted net loss per common share (1.04 ) (0.41 ) (0.87 ) (0.66 ) Three Months Ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Contract revenue 4,664 4,476 12,041 4,880 Operating expenses 15,548 13,006 12,970 11,110 Other income (expense), net (382 ) (232 ) 43 51 Net loss (11,266 ) (8,762 ) (886 ) (6,179 ) Basic and diluted net loss per common share (0.61 ) (0.48 ) (0.05 ) (0.34 ) Three Months Ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Contract revenue 4,259 4,520 5,203 5,988 Operating expenses 9,140 12,853 8,541 9,222 Other income and expense, net 27 21 (217 ) (221 ) Net loss (4,854 ) (8,312 ) (3,555 ) (3,455 ) Basic and diluted net loss per common share (0.27 ) (0.47 ) (0.20 ) (1.00 ) (1) Basic and diluted net loss per common share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted net loss per common share.

Organization and Basis of Pre33

Organization and Basis of Presentation and Consolidation - Additional Information (Details) - USD ($)	Dec. 19, 2016	Jun. 03, 2016	Mar. 14, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Apr. 07, 2015
Subsidiary, Sale of Stock [Line Items]
Shares issued for underwriters' granted of their over-allotment option (shares)				900,000
Net proceeds from initial public offering				$ 73,900,000			$ 73,936,000
Preferred shares converted (shares)			10,386,894	10,386,894
Value authorized of equity instruments to be issued									$ 150,000,000
Proceeds from sale of stock, net of commissions and other transaction costs					$ 3,827,000	$ 1,319,000
Warrants to purchase common stock, exercise price					$ 3.85			$ 3.85
Cash, cash equivalents and short-term investments					$ 145,900,000			$ 145,900,000
Accumulated deficit					$ 247,220,000	$ 175,993,000		$ 247,220,000
ATM equity offering program
Subsidiary, Sale of Stock [Line Items]
Shares issued					1,105,549			1,105,549
Value authorized of equity instruments to be issued									30,000,000
Share price (dollars per share)					$ 4.82			$ 4.82
Proceeds from issuance of common stock, gross of issuance costs					$ 5,300,000
Proceeds from sale of stock, net of commissions and other transaction costs					$ 5,100,000
Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued					907,711	197,838	6,900,000
Value authorized of equity instruments to be issued									$ 30,000,000
Share price (dollars per share)					$ 4.82			4.82
Proceeds from issuance of common stock, gross of issuance costs					$ 5,300,000
Initial Public Offering
Subsidiary, Sale of Stock [Line Items]
Shares issued				6,900,000
Number of shares authorized to be purchased				40,454
Warrants to purchase common stock, exercise price				$ 12.36
Private Placement
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance or sale of equity		$ 25,400,000			$ 25,400,000
Aggregate net proceeds from issuance of common stock		$ 25,100,000
Warrants to purchase common stock, exercise price		$ 3.66			$ 3.66			$ 3.66
Weighted average contractual term		5 years
Private Placement | Maximum
Subsidiary, Sale of Stock [Line Items]
Weighted average contractual term		5 years			5 years
Private Placement | Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued		7,999,996			7,999,996
Number of shares authorized to be purchased		1,999,999			1,999,999			1,999,999
Underwritten Public Offering
Subsidiary, Sale of Stock [Line Items]
Shares issued	7,475,000
Share price (dollars per share)	$ 13.50
Additional shares of common stock	975,000
Proceeds from offering net of underwriting discounts and commissions and estimated offering expenses	$ 94,600,000

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Information (Details)	Jun. 03, 2016$ / sharesshares	Dec. 31, 2016USD ($)Segment$ / sharesshares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Summary of Significant Accounting Policies [Line Items]
Restricted cash		$ 377,000	$ 127,000
Restricted cash, current		$ 127,000	0
Facility lease expiration date		Apr. 14, 2017
Number of operating segments | Segment		1
Allowance for doubtful accounts receivable		$ 0	0
Warrants to purchase common stock, exercise price | $ / shares		$ 3.85
Private Placement
Summary of Significant Accounting Policies [Line Items]
Warrants to purchase common stock, exercise price | $ / shares	$ 3.66	$ 3.66
Weighted average contractual term	5 years
Common Stock | Private Placement
Summary of Significant Accounting Policies [Line Items]
Number of shares authorized to be purchased | shares	1,999,999	1,999,999
Impairment of Asset
Summary of Significant Accounting Policies [Line Items]
Impairment charges		$ 0	$ 0	$ 0
Minimum
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		3 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		7 years
Maximum | Private Placement
Summary of Significant Accounting Policies [Line Items]
Weighted average contractual term	5 years	5 years

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Cash and cash equivalents	$ 118,964	$ 20,287	$ 18,881
Restricted cash, current	127	0
Restricted cash, non current	250	127	127
Total cash, cash equivalents, and restricted cash	$ 119,341	$ 20,414	$ 19,008	$ 10,865

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Computation of the Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (29,724)	$ (11,038)	$ (18,268)	$ (12,197)	$ (11,266)	$ (8,762)	$ (886)	$ (6,179)	$ (4,854)	$ (8,312)	$ (3,555)	$ (3,455)	$ (71,227)	$ (27,093)	$ (20,176)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share													23,707,063	18,147,986	14,210,098
Basic and diluted net loss per common share													$ (3)	$ (1.49)	$ (1.42)
Accumulated Deficit
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss													$ (71,227)	$ (27,093)	$ (20,176)

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Outstanding Excluded from the Computations of Diluted Weighted-Average Shares Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding (shares)	3,540,293	2,387,337	1,885,372
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding (shares)	605,052	372,024	168,200
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding (shares)	1,322,754	30,024	40,454

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured and Recognized at Fair Value (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant Liability	$ 13,874,000	$ 0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	146,260,000	58,906,000
Unrealized Losses	(7,000)	(48,000)
Fair Value	146,253,000	58,858,000
Fair Value, Measurements, Recurring | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	26,912,000	38,444,000
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	3,728,000	1,013,000
Fair Value	3,728,000	1,013,000
Fair Value, Measurements, Recurring | Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	377,000	127,000
Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	118,964,000	20,287,000
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	115,613,000	19,401,000
Fair Value	115,613,000	19,401,000
Fair Value, Measurements, Recurring | Level 1 | Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	377,000	127,000
Fair Value	377,000	127,000
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	115,236,000	19,274,000
Fair Value	115,236,000	19,274,000
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	26,919,000	38,492,000
Unrealized Losses	(7,000)	(48,000)
Fair Value	26,912,000	38,444,000
Fair Value, Measurements, Recurring | Level 2 | US Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		2,005,000
Unrealized Losses		(1,000)
Fair Value		2,004,000
Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	12,969,000	34,490,000
Unrealized Losses	(7,000)	(47,000)
Fair Value	12,962,000	34,443,000
Fair Value, Measurements, Recurring | Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	13,950,000	1,997,000
Fair Value	13,950,000	1,997,000
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant Liability	13,874,000
Derivative Liability	602,000	375,000
Total	14,476,000
Fair Value, Measurements, Recurring | Level 3 | Derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	602,000
Total	$ 602,000	$ 375,000

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Jun. 03, 2016	Aug. 05, 2015	Feb. 28, 2017	Dec. 31, 2016	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Sale of available-for-sale securities						$ 0	$ 0
Change in estimated fair value						19,859,000	19,000
Potential payment to solar capital				$ 1,000,000		$ 1,000,000
Discount rate, percent						13.00%
Change in percent effecting fair value of derivative liability						5.00%
Effect in fair value of derivative liability due to change in percent of FDA approval probability				$ 801,000		$ 801,000
Warrants to purchase common stock, exercise price				$ 3.85		$ 3.85
Issuance of derivative in connection with issuance of loan payable							356,000
Warrant Liability				$ 13,874,000		$ 13,874,000	0
Exercise of Warrants				707,269		707,269
Proceeds from exercise of stock warrants				$ 1,200,000		$ 1,151,000		$ 2,000
Estimated fair value of warrants exercised	$ 900,000			8,300,000		$ 8,300,000
Increase in estimated fair value of warrants exercised				$ 7,400,000				42,000
Dividend yield						0.00%
Fair Value of Derivative Liability, Benefit Conversion, Percentage						20.00%
Reclassification of warrant liability to additional paid-in capital					$ 286,000	$ 8,337,000		286,000
Subsequent Event
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Exercise of Warrants			78,585
Proceeds from exercise of stock warrants			$ 300,000
Private Placement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants to purchase common stock, exercise price	$ 3.66			$ 3.66		$ 3.66
IPO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants to purchase common stock					40,454
Warrants to purchase common stock, exercise price					$ 12.36
Common Stock | Private Placement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants to purchase common stock	1,999,999			1,999,999		1,999,999
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability				$ 602,000		$ 602,000	375,000
Warrant Liability				13,874,000		13,874,000
Fair value, derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of success fee							$ 375,000
Effect in fair value of derivative liability due to change in percent of FDA approval probability				36,000		36,000
Convertible Preferred Stock Warrant Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in estimated fair value recognized in net loss					$ 42,000
Convertible Preferred Stock Warrant Liabilities | Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liabilities									$ 244,000
Convertible Preferred Stock Warrant Liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in estimated fair value								$ 42,000
Derivative | Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in estimated fair value						227,000
Derivative liability				602,000		602,000
Warrants to purchase common stock | Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in estimated fair value						19,632,000
Issuance of derivative in connection with issuance of loan payable	$ 2,600,000					2,579,000
Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success fee		$ 1,000,000
Fair value of success fee		$ 356,000
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized loss position				$ 13,000,000		$ 13,000,000

Fair Value Measurements - Assum

Fair Value Measurements - Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Dividend yield	0.00%
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Expected volatility	60.00%
Expected term	4 years 4 months 24 days
Risk-free interest rate	1.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Expected volatility	80.00%
Expected term	5 years
Risk-free interest rate	1.90%

Fair Value Measurements - Prefe

Fair Value Measurements - Preferred Stock Warrant Liability (Details) - USD ($)	Jun. 03, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated fair value of derivative liability and warrants issued			$ 356,000
Change in estimated fair value		$ 19,859,000	19,000
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated Fair value, Beginning Balance
Estimated fair value, Ending Balance		14,476,000
Level 3 | Fair Value, Measurements, Recurring | Derivative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated Fair value, Beginning Balance		375,000
Change in estimated fair value		227,000
Estimated fair value, Ending Balance		602,000	375,000
Level 3 | Fair Value, Measurements, Recurring | Warrants to purchase common stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated fair value of derivative liability and warrants issued	$ 2,600,000	2,579,000
Change in estimated fair value		19,632,000
Reclassification of warrant liability to additional paid-in capital		(8,337,000)
Estimated fair value, Ending Balance		13,874,000
Level 3 | Estimated Fair Value of Derivative Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated Fair value, Beginning Balance		$ 375,000
Estimated fair value of derivative liability and warrants issued			356,000
Change in estimated fair value			19,000
Estimated fair value, Ending Balance			$ 375,000
Level 3 | Convertible Preferred Stock Warrant Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Estimated Fair value, Beginning Balance				$ 244,000
Change in estimated fair value				42,000
Reclassification of warrant liability to additional paid-in capital				$ (286,000)

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7,650	$ 5,377
Less: accumulated depreciation and amortization	(4,389)	(4,472)
Property and equipment, net	3,261	905
Office equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	644	1,144
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,038	3,161
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,072	$ 1,072
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,896

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Depreciation and amortization expense	$ 441	$ 426	$ 358

Balance Sheet Components - Sc44

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued clinical and development expenses	$ 3,681	$ 2,869
Payroll and related bonus expenses	4,941	1,615
Other	1,076	443
Accrued liabilities	$ 9,698	$ 4,927

License and Collaboration Agr45

License and Collaboration Agreements - Additional Information (Details) - USD ($)	1 Months Ended			12 Months Ended
	May 31, 2016	Apr. 30, 2016	Jan. 31, 2006	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense				$ 73,999,000	$ 40,228,000	$ 30,110,000
Thermo Fisher Scientific, Inc
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments for first commercialization product		$ 6,453,000
Research and development expense				1,204,000
Crystal Biosciences, Inc
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments for first commercialization product	$ 20,550,000
Ionis Pharmaceuticals License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments for first commercialization product			$ 19,500,000
Milestone payments for second commercialization product			9,750,000
Aggregate additional milestone payments			20,000,000
Cash payment of research and development expense						$ 4,000,000
Payments due				$ 0	$ 0
Ionis Pharmaceuticals License Agreement | Up-front License Fee
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense			$ 1,500,000
Ionis Pharmaceuticals License Agreement | Up-front License Fee | Series A Convertible Preferred Stock
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shares issued			97,402
Shares issued price per share (dollars per share)			$ 15.40

Government Contracts - Addition

Government Contracts - Additional Information (Details) - USD ($)	1 Months Ended								12 Months Ended
	May 26, 2016	Apr. 30, 2016	Jan. 31, 2016	Jul. 31, 2015	Jul. 31, 2014	Apr. 30, 2013	Sep. 30, 2012	Aug. 31, 2010	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
BARDA
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development contract	$ 123,808,000					$ 103,808,000	$ 43,398,000	$ 27,600,000
Term of agreement, in years								2 years
Increase in research and development contract	$ 20,000,000					$ 60,410,000
Research and development, remaining available funding									$ 7,227,000
Contracts revenue									39,462,000	$ 17,569,000	$ 19,970,000
Contracts receivable									11,668,000	4,657,000
DTRA
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contracts revenue										7,122,000
NIAID
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development contract		$ 4,400,000		$ 1,500,000	$ 407,000
Term of agreement, in years					1 year
Increase in research and development contract			$ 500,000
Contracts revenue									2,311,000	1,370,000	$ 0
Contracts receivable									$ 483,000	$ 382,000
Aggregate research and development grant and other revenues		$ 5,000,000	$ 5,000,000	$ 4,500,000

Commitments - Facilities Lease

Commitments - Facilities Lease Obligation (Details)	Aug. 31, 2016USD ($)ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Operating Leased Assets [Line Items]
Square feet of office, laboratory and research and development space (sq feet) | ft²	47,000
Expansion option (in years)	5 years
First year base rent	$ 2,700,000
Lessor Leasing Arrangements, Operating Leases, Rental Increase, Percent	3.50%
One time, first year rent abatement	$ 1,800,000
One time improvement allowance	5,700,000
Property, Plant and Equipment, Gross		$ 7,650,000	$ 5,377,000
Additional allowance	$ 900,000
Restricted cash, non current		250,000	127,000	$ 127,000
Rent expense		581,000	526,000	405,000
Sublease income		0	$ 0	$ 97,000
Construction-in-progress
Operating Leased Assets [Line Items]
Property, Plant and Equipment, Gross		$ 1,896,000

Commitments - Schedule of Futur

Commitments - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Year-ended December 31,
2,017	$ 1,103
2,018	2,500
2,019	2,890
2,020	2,991
2,021	3,098
Thereafter	19,717
Total minimum lease payments	$ 32,299

Commitments - Nonrefundable Adv

Commitments - Nonrefundable Advance Payments (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Prepaid and other current assets		$ 2,189,000	$ 1,719,000
Research and development		73,999,000	$ 40,228,000	$ 30,110,000
Pharmaceutical Contract Manufacturing Organization
Loss Contingencies [Line Items]
Advance payments	$ 1,500,000
Prepaid and other current assets		660,000
Research and development		$ 840,000

Borrowings - Additional Informa

Borrowings - Additional Information (Details) - USD ($)	Jun. 20, 2016	Aug. 05, 2015	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012	Apr. 30, 2012	Dec. 31, 2011	Nov. 30, 2011
Debt Instrument [Line Items]
Face amount				$ 25,000,000
Proceeds from issuance of loan payable				10,000,000	$ 14,590,000
Interest expense				$ 2,320,000	699,000	$ 397,000
Repayments of notes payable						6,896,000
Warrants to purchase common stock, exercise price				$ 3.85
Secured Debt
Debt Instrument [Line Items]
Face amount		$ 25,000,000
Proceeds from issuance of loan payable	$ 10,000,000	$ 15,000,000
Interest rate per annum (percent)		6.99%
Repayment of debt term (months)		24 months
Increase in interest rate in event of default (percent)		4.00%
Closing fee		$ 250,000
Final fee (percent)		8.00%
Success fee		$ 1,000,000
Fair value of success fee		356,000
Final fee due at maturity in 2019		$ 2,000,000
Interest expense				$ 2,320,000	$ 699,000
Secured Debt | One-month LIBOR
Debt Instrument [Line Items]
Variable interest rate (percent)		1.00%
Notes Payable to Banks | Oxford Finance LLC and SVB
Debt Instrument [Line Items]
Face amount								$ 8,000,000		$ 4,000,000
Interest expense						$ 397,000
Debt effective interest rate								8.22%		8.18%
Debt termination payment percentage				8.25%
Repayments of notes payable			$ 4,454,000
Notes Payable to Banks | Oxford Finance LLC and SVB | Series C Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase shares of stock, shares							20,016		10,008
Warrants to purchase common stock, exercise price							$ 11.99
Fair value of warrants							$ 163,000		$ 86,000
Notes Payable to Banks | Three-month LIBOR | Oxford Finance LLC and SVB
Debt Instrument [Line Items]
Variable interest rate (percent)				7.75%

Borrowings - Future Minimum Deb

Borrowings - Future Minimum Debt Obligation Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
2,017	$ 4,167
2,018	12,500
2,019	8,333
Total principal payments	25,000
Final fee due at maturity in 2019	2,000
Total principal and final fee payments	27,000
Unamortized discount and debt issuance costs	(1,723)
Less current portion	(4,167)	$ 0
Loan payable, long term	$ 21,110	$ 14,536

Stockholders' Equity and Conv52

Stockholders' Equity and Convertible Preferred Stock - Additional Information (Details)	Jun. 03, 2016USD ($)$ / sharesshares	Mar. 14, 2014shares	Feb. 28, 2017USD ($)shares	Dec. 31, 2016USD ($)$ / sharesshares	Mar. 31, 2014shares	Nov. 30, 2013USD ($)$ / sharesshares	May 31, 2013USD ($)Tranche$ / sharesshares	Mar. 31, 2013USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Dec. 31, 2016USD ($)$ / sharesshares	Apr. 07, 2015USD ($)	Mar. 17, 2014
Stockholders Equity And Convertible Preferred Stock [Line Items]
Value authorized of equity instruments to be issued													$ 150,000,000
Value of common stock remaining available to be sold				$ 24,700,000					$ 24,700,000			$ 24,700,000
Conversion of preferred stock to common stock upon initial public offering | shares		10,386,894			10,386,894
Warrants to purchase common stock, exercise price | $ / shares				$ 3.85					$ 3.85			$ 3.85
Estimated fair values of the common stock and warrants issued									$ 3,827,000	$ 1,319,000	$ 73,936,000
Issuance of derivative in connection with issuance of loan payable										$ 356,000
Exercise of Warrants | shares				707,269					707,269
Issuance of common stock upon exercise of warrant shares | shares									610,490
Estimated fair value on exercise of warrants.									$ 8,300,000
Increase in estimated fair value of warrants									7,400,000
Proceeds from exercise of stock warrants				$ 1,200,000					1,151,000		$ 2,000
Subsequent Event
Stockholders Equity And Convertible Preferred Stock [Line Items]
Exercise of Warrants | shares			78,585
Issuance of common stock upon exercise of warrant shares | shares			84,481
Proceeds from exercise of stock warrants			$ 300,000
Level 3 | Fair Value, Measurements, Recurring
Stockholders Equity And Convertible Preferred Stock [Line Items]
Remaining Warrants outstanding				$ 13,900,000					13,900,000			$ 13,900,000
Warrants to purchase common stock | Subsequent Event
Stockholders Equity And Convertible Preferred Stock [Line Items]
Exercise of Warrants | shares			91,095
Warrants to purchase common stock | Level 3 | Fair Value, Measurements, Recurring
Stockholders Equity And Convertible Preferred Stock [Line Items]
Issuance of derivative in connection with issuance of loan payable	$ 2,600,000								2,579,000
Change in estimated fair value of remaining warrants outstanding									12,200,000
Private Placement
Stockholders Equity And Convertible Preferred Stock [Line Items]
Proceeds from issuance or sale of equity	$ 25,400,000								$ 25,400,000
Warrants to purchase common stock, exercise price | $ / shares	$ 3.66			$ 3.66					$ 3.66			$ 3.66
Weighted average contractual term	5 years
Payments of stock issuance costs	$ 300,000
Estimated fair values of the common stock and warrants issued									$ 22,587,000
Private Placement | Chief Operating Officer
Stockholders Equity And Convertible Preferred Stock [Line Items]
Shares issued | shares	141,453								141,453
Proceeds from issuance or sale of equity	$ 500,000								$ 500,000
Number of shares authorized to be repurchased | shares	35,363								35,363
Series A Preferred Stock
Stockholders Equity And Convertible Preferred Stock [Line Items]
Conversion of stock, conversion ratio														1.15%
Series B Preferred Stock
Stockholders Equity And Convertible Preferred Stock [Line Items]
Conversion of stock, conversion ratio														1.33%
Series C Preferred Stock
Stockholders Equity And Convertible Preferred Stock [Line Items]
Conversion of stock, conversion ratio														1.00%
Series D Preferred Stock
Stockholders Equity And Convertible Preferred Stock [Line Items]
Share price (dollars per share) | $ / shares						$ 11.99	$ 11.99	$ 11.99
Conversion of stock, conversion ratio														1.00%
Number of tranches | Tranche							2
Convertible preferred stock, shares issued | shares						834,031	148,289	1,110,252
Proceeds from issuance of convertible preferred stock, net of issuance costs						$ 10,000,000	$ 1,778,000	$ 10,581,000
Convertible preferred stock amount on conversion								$ 2,732,000
Common Stock
Stockholders Equity And Convertible Preferred Stock [Line Items]
Value authorized of equity instruments to be issued													30,000,000
Shares issued | shares									907,711	197,838	6,900,000
Share price (dollars per share) | $ / shares				$ 4.82					$ 4.82			$ 4.82
Proceeds from issuance of common stock, gross of issuance costs									$ 5,300,000
Proceeds from sale of stock, net of commissions and other transaction costs									5,100,000
Estimated fair values of the common stock and warrants issued									$ 1,000		$ 7,000
Common Stock | Private Placement
Stockholders Equity And Convertible Preferred Stock [Line Items]
Shares issued | shares	7,999,996								7,999,996
Number of shares authorized to be purchased | shares	1,999,999			1,999,999					1,999,999			1,999,999
Estimated fair values of the common stock and warrants issued	$ 22,900,000								$ 8,000
ATM equity offering program
Stockholders Equity And Convertible Preferred Stock [Line Items]
Value authorized of equity instruments to be issued													$ 30,000,000
Shares issued | shares									1,105,549			1,105,549
Share price (dollars per share) | $ / shares				$ 4.82					$ 4.82			$ 4.82
Proceeds from issuance of common stock, gross of issuance costs									$ 5,300,000

Stockholders' Equity and Conv53

Stockholders' Equity and Convertible Preferred Stock - Summary of Warrants to Purchase Shares of Common Stock (Details)	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Class of Warrant or Right [Line Items]
Shares | shares	1,322,754
Exercise Price | $ / shares	$ 3.85
April 30, 2012 Warrants | Oxford Finance LLC
Class of Warrant or Right [Line Items]
Shares | shares	11,676
Exercise Price | $ / shares	$ 11.99
Expiration Date	Nov. 1, 2021
April 30, 2012 Warrants | SVB
Class of Warrant or Right [Line Items]
Shares | shares	8,340
Exercise Price | $ / shares	$ 11.99
Expiration Date	Nov. 1, 2021
November 1, 2011 Warrants | Oxford Finance LLC
Class of Warrant or Right [Line Items]
Shares | shares	5,838
Exercise Price | $ / shares	$ 11.99
Expiration Date	Nov. 1, 2021
November 1, 2011 Warrants | SVB
Class of Warrant or Right [Line Items]
Shares | shares	4,170
Exercise Price | $ / shares	$ 11.99
Expiration Date	Nov. 1, 2021
June 3, 2016 Warrants | Growth Equity Opportunities Fund IV, LLC
Class of Warrant or Right [Line Items]
Shares | shares	1,178,782
Exercise Price | $ / shares	$ 3.66
Expiration Date	Jun. 3, 2021
June 3, 2016 Warrants | DAFNA Lifescience, L.P.
Class of Warrant or Right [Line Items]
Shares | shares	47,151
Exercise Price | $ / shares	$ 3.66
Expiration Date	Jun. 3, 2021
June 3, 2016 Warrants | DAFNA Lifescience Select, L.P.
Class of Warrant or Right [Line Items]
Shares | shares	31,434
Exercise Price | $ / shares	$ 3.66
Expiration Date	Jun. 3, 2021
June 3, 2016 Warrants | Blake A. Wise Trust
Class of Warrant or Right [Line Items]
Shares | shares	35,363
Exercise Price | $ / shares	$ 3.66
Expiration Date	Jun. 3, 2021

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Detail) - USD ($)	Mar. 17, 2016	Jan. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 28, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized			1,235,808	716,285	1,190,908
Outstanding shares available for future issuance (shares)			639,374	893,462	1,111,470		127,277
Shares subject to options outstanding (shares)			3,540,293	2,387,337	1,885,372		1,405,550
Options granted (shares)			1,477,600	929,100	876,163
Options granted, weighted average grant date fair value (in dollars per share)			$ 4.10	$ 5.02	$ 6.41
Unrecognized stock-based compensation			$ 6,695,000
Weighted-average period of cost expected to be recognized			2 years 11 months 16 days
Stock-based compensation expense			$ 3,847,000	$ 2,983,000	$ 2,050,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued (shares)			145,724	61,742	17,795
Options granted (shares)			354,250	0	168,977
Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (shares)			15,000	0	0
Stock-based compensation expense			$ 71,000
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Options granted (shares)			59,925	0	0
Weighted-average period of cost expected to be recognized			2 years 9 months 11 days
Shares granted			380,500	291,525	168,200
Weighted-average grant date fair market value, shares granted (dollars per share)			$ 4.01	$ 7.76	$ 9.33
Unrecognized compensation costs			$ 2,853,000
2014 Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized		735,808
Outstanding shares available for future issuance (shares)			621,286
Vesting period			4 years
Option expiration period			10 years
2014 Employment Commencement Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized	500,000				650,000
Outstanding shares available for future issuance (shares)			18,088
Number of shares authorized (shares)			1,150,000
Employee Stock Purchase Plan | Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized		183,952
Outstanding shares available for future issuance (shares)			283,216			145,454
Common stock issued (shares)			225,261
Stock Incentive Plan 2003
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Option expiration period			10 years
Shares subject to options outstanding (shares)			877,234

Equity Incentive Plans - Schedu

Equity Incentive Plans - Schedule of Stock-Based Compensation Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 3,847	$ 2,983	$ 2,050
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,165	1,404	570
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,682	$ 1,579	$ 1,480

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 17, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares Available for grant
Beginning balance (shares)		893,462	1,111,470	127,277
Additional shares reserved (shares)		1,235,808	716,285	1,190,908
Options granted (shares)		(1,477,600)	(929,100)	(876,163)
Options exercised (shares)		0	0	0
Options forfeited (shares)		310,454	237,007	187,648
Ending balance (shares)		639,374	893,462	1,111,470
Number of Shares
Beginning balance (shares)		2,387,337	1,885,372	1,405,550
Additional shares reserved (shares)		0	0	0
Options granted (shares)		1,477,600	929,100	876,163
Options exercised (shares)		(14,190)	(190,128)	(208,693)
Options forfeited (shares)		(310,454)	(237,007)	(187,648)
Ending balance (shares)		3,540,293	2,387,337	1,885,372
Vested and exercisable		1,315,306
Vested and expected to vest		3,453,530
Weighted- Average Exercise Price
Beginning balance (shares)		$ 7.92	$ 7.95	$ 5.68
Options granted (shares)		4.10	7.95	10.15
Options exercised (shares)		4.59	5.54	3.38
Options forfeited (shares)		8.19	10.22	6.29
Ending balance (shares)		6.31	$ 7.92	$ 7.95
Vested and exercisable		7.41
Vested and expected to vest		$ 6.27
Weighted-Average Remaining Contractual Life (in years)
Options vested and exercisable, weighted-average remaining contractual life (in years)		6 years 8 months 16 days
Options vested and expected to vest, weighted-average remaining contractual life (in years)		8 years 7 days
Weighted- Average Remaining Contractual Term (years)		7 years 11 months 23 days
Aggregate Intrinsic Value (in thousands)
Options exercised, aggregate intrinsic value		$ 89	$ 923	$ 1,704
Outstanding options, aggregate intrinsic value		293
Outstanding options, aggregate intrinsic value		23,837	$ 293
Options vested and exercisable, aggregate intrinsic value		7,441
Options vested and expected to vest, aggregate intrinsic value		$ 23,408
Restricted stock units
Shares Available for grant
Shares granted		(380,500)	(291,525)	(168,200)
Shares cancelled		57,750	49,325
Number of Shares
Options granted (shares)		59,925	0	0
2014 Employment Commencement Incentive Plan
Shares Available for grant
Additional shares reserved (shares)	500,000			650,000
Ending balance (shares)		18,088

Equity Incentive Plans - Summ57

Equity Incentive Plans - Summary of Stock Options Outstanding by Exercise Price Range (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Options (in shares)	3,540,293	2,387,337	1,885,372	1,405,550
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	7 years 11 months 23 days
Vested and Exercisable, Number of Options (in shares)	1,315,306
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 7.41
$2.64 - $3.41
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	2.64
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 3.41
Options Outstanding, Number of Options (in shares)	1,137
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	1 year 1 month 17 days
Vested and Exercisable, Number of Options (in shares)	1,137
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 2.69
$ 3.65
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	3.65
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 3.65
Options Outstanding, Number of Options (in shares)	504,153
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	9 years 1 month 28 days
Vested and Exercisable, Number of Options (in shares)	64,101
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 3.65
$3.68 - $4.34
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	3.68
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 4.34
Options Outstanding, Number of Options (in shares)	605,058
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	9 years 4 months 10 days
Vested and Exercisable, Number of Options (in shares)	12,429
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 4.27
$4.44 - $4.84
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	4.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 4.84
Options Outstanding, Number of Options (in shares)	362,041
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	7 years 6 months 7 days
Vested and Exercisable, Number of Options (in shares)	199,867
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 4.73
$4.86 - $5.86
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	4.86
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 5.86
Options Outstanding, Number of Options (in shares)	458,062
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	9 years 1 month 6 days
Vested and Exercisable, Number of Options (in shares)	115,516
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 5.73
$6.60 - $6.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	6.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 6.99
Options Outstanding, Number of Options (in shares)	447,807
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	6 years 3 months
Vested and Exercisable, Number of Options (in shares)	297,277
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 6.91
$7.08 - $8.04
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	7.08
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 8.04
Options Outstanding, Number of Options (in shares)	546,877
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	6 years 6 months
Vested and Exercisable, Number of Options (in shares)	294,696
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 7.53
$9.21 - $10.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	9.21
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 10.44
Options Outstanding, Number of Options (in shares)	409,489
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	7 years 8 months 1 day
Vested and Exercisable, Number of Options (in shares)	205,140
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 9.65
$11.78 - $12.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	11.78
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 12.22
Options Outstanding, Number of Options (in shares)	152,659
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	7 years 10 months 17 days
Vested and Exercisable, Number of Options (in shares)	88,818
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 11.93
$ 14.89
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	14.89
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 14.89
Options Outstanding, Number of Options (in shares)	53,010
Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	7 years 2 months 1 day
Vested and Exercisable, Number of Options (in shares)	36,325
Vested and Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 14.89

Equity Incentive Plans - Sche58

Equity Incentive Plans - Schedule of Estimated Grant Date Fair Value of Employee Stock Options Using Black-Scholes Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected volatility, minimum	67.00%	65.00%	67.00%
Expected volatility, maximum	74.00%	75.00%	77.00%
Risk-free interest rate, minimum	1.10%	1.50%	1.70%
Risk-free interest rate maximum	1.90%	1.90%	2.00%
Expected dividend yield	0.00%	0.00%	0.00%
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	6 years	6 years	6 years 1 month 6 days
Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	5 years 3 months 18 days	5 years 4 months 24 days	5 years 3 months 18 days

Equity Incentive Plans - Sche59

Equity Incentive Plans - Schedule of Estimated Grant Date Fair Value of Employee Stock Options (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected volatility, minimum	67.00%	65.00%	67.00%
Expected volatility, maximum	74.00%	75.00%	77.00%
Risk-free interest rate, minimum	1.10%	1.50%	1.70%
Risk-free interest rate maximum	1.90%	1.90%	2.00%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	5 years 3 months 18 days	5 years 4 months 24 days	5 years 3 months 18 days
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	6 years	6 years	6 years 1 month 6 days
Black Scholes | Non-Employees
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected volatility, minimum	63.00%
Expected volatility, maximum	125.00%
Risk-free interest rate, minimum	0.60%
Risk-free interest rate maximum	0.90%
Expected dividend yield	0.00%
Black Scholes | Non-Employees | Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	9 months 18 days
Black Scholes | Non-Employees | Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	1 year
Monte Carlo Simulation
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected volatility, minimum			60.00%
Expected volatility, maximum			70.00%
Risk-free interest rate, minimum	1.40%		2.50%
Risk-free interest rate maximum	2.30%		2.80%
Expected dividend yield	0.00%		0.00%
Expected volatility	70.00%
Monte Carlo Simulation | Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	2 years 2 months 12 days		2 years 10 months 24 days
Monte Carlo Simulation | Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Expected term (years)	6 years		6 years 3 months 18 days

Equity Incentive Plans - Summ60

Equity Incentive Plans - Summary of Restricted Stock Activity (Details) - Restricted stock units - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Beginning balance (shares)	372,024	168,200	0
Shares granted	380,500	291,525	168,200
Shares released	(89,722)	(38,376)
Shares cancelled	(57,750)	(49,325)
Ending balance (shares)	605,052	372,024	168,200
Weighted-Average Grant Date Fair Market Value
Beginning balance (dollars per share)	$ 8.02	$ 9.33	$ 0
Shares granted (dollars per share)	4.01	7.76	9.33
Shares released (dollars per share)	8.22	9.42
Shares canceled (dollars per share)	6.71	9.80
Ending balance (dollars per share)	$ 5.60	$ 8.02	$ 9.33
Aggregate Intrinsic Value (in thousands)
RSU Awards Outstanding, aggregate intrinsic value	$ 7,878	$ 2,135	$ 2,195	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Statutory Tax Rates and the Effective Tax Rates (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefits	0.96%	(3.62%)	5.04%
Stock-based compensation	(0.62%)	(1.20%)	(0.76%)
Credits	1.46%	3.30%	3.21%
Other	(0.10%)	(0.54%)	(1.74%)
Valuation allowance	(26.22%)	(31.94%)	(39.75%)
Warrant Valuation	(9.48%)	(0.00%)	(0.00%)
Effective tax rate	0.00%	0.00%	0.00%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carry forwards	$ 71,858	$ 57,558
Research and development credit	10,969	8,531
Intangible assets	1,653	1,994
Depreciation	191	195
Temporary differences	4,682	2,396
Gross Deferred tax assets	89,353	70,674
Less: valuation allowance	$ (89,353)	$ (70,674)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes Disclosure [Line Items]
Increase (decrease) in valuation allowance	$ 18,679,000	$ 7,975,000
Unrecognized tax benefits that would impact effective tax rate	1,024,000	$ 820,000	$ 678,000
Unrecognized tax benefit, penalties and interest accrued	0
Domestic Tax Authority
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 196,669,000
Operating loss carryforwards expiration start year	2,023
State and Local Jurisdiction
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 90,810,000
Operating loss carryforwards expiration start year	2,017
Research Tax Credit Carryforward | Domestic Tax Authority
Income Taxes Disclosure [Line Items]
Tax credit carryforward	$ 8,965,000
Tax credit carryforward expiration start year	2,025
Research Tax Credit Carryforward | State and Local Jurisdiction
Income Taxes Disclosure [Line Items]
Tax credit carryforward	$ 5,186,000

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefit Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Unrecognized Tax Benefit
Balance at beginning of year	$ 957
Increase related to current year tax provision	240	$ 162
Increase related to prior year tax provision		795
Balance at end of year	$ 1,197	$ 957

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($)	1 Months Ended			12 Months Ended
	Dec. 31, 2015	Jan. 31, 2011	Dec. 31, 2010	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2003
Compensation And Retirement Disclosure [Abstract]
Maximum annual contributions per employee, percent							100.00%
Employer matching contribution, percent of match			50.00%
Employer matching contribution, percent of employees' gross pay	8.00%	6.00%
Defined contribution plan, cost recognized				$ 469,000	$ 255,000	$ 184,000

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 03, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Warrants to purchase common stock, exercise price		$ 3.85
Common Stock
Related Party Transaction [Line Items]
Shares issued		907,711	197,838	6,900,000
Private Placement
Related Party Transaction [Line Items]
Proceeds from issuance or sale of equity	$ 25.4	$ 25.4
Warrants to purchase common stock, exercise price	$ 3.66	$ 3.66
Weighted average contractual term	5 years
Private Placement | Chief Operating Officer
Related Party Transaction [Line Items]
Shares issued	141,453	141,453
Proceeds from issuance or sale of equity	$ 0.5	$ 0.5
Number of shares authorized to be repurchased	35,363	35,363
Private Placement | Common Stock
Related Party Transaction [Line Items]
Shares issued	7,999,996	7,999,996
Number of shares authorized to be purchased	1,999,999	1,999,999
Private Placement | Maximum
Related Party Transaction [Line Items]
Weighted average contractual term	5 years	5 years

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Subsequent Event - Hovione Limited	Mar. 14, 2017
Subsequent Event [Line Items]
Commercial manufacturing agreement initial term	7 years
Percentage of long term purchase commitment minimum required quantity	80.00%
Number of years for minimum supply percentage after approval	3 years
Minimum annual purchase commitments beginning year	2,020
Annual purchase commitments ending Year	2,024
Minimum
Subsequent Event [Line Items]
Percentage of long term purchase commitment	40.00%
Maximum
Subsequent Event [Line Items]
Percentage of long term purchase commitment	66.00%

Selected Unaudited Quarterly 68

Selected Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Contract revenue	$ 10,734	$ 16,046	$ 9,144	$ 5,849	$ 4,664	$ 4,476	$ 12,041	$ 4,880	$ 4,259	$ 4,520	$ 5,203	$ 5,988	$ 41,773	$ 26,061	$ 19,970
Operating expenses	22,796	24,996	25,659	17,670	15,548	13,006	12,970	11,110	9,140	12,853	8,541	9,222	91,121	52,634	39,756
Other income (expense), net	(17,662)	(2,088)	(1,753)	(376)	(382)	(232)	43	51	27	21	(217)	(221)	300	198	7
Net loss	$ (29,724)	$ (11,038)	$ (18,268)	$ (12,197)	$ (11,266)	$ (8,762)	$ (886)	$ (6,179)	$ (4,854)	$ (8,312)	$ (3,555)	$ (3,455)	$ (71,227)	$ (27,093)	$ (20,176)
Basic and diluted net loss per common share	$ (1.04)	$ (0.41)	$ (0.87)	$ (0.66)	$ (0.61)	$ (0.48)	$ (0.05)	$ (0.34)	$ (0.27)	$ (0.47)	$ (0.20)	$ (1)	$ (3)	$ (1.49)	$ (1.42)