Aimmune Therapeutics (AIMT) 10-K 15 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Mar. 10, 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	AIMT
Entity Registrant Name	AIMMUNE THERAPEUTICS, INC.
Entity Central Index Key	1,631,650
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		50,249,376
Entity Public Float			$ 365,306,236

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 124,010	$ 76,677
Short-term investments	124,921	115,158
Prepaid expenses and other current assets	2,749	5,622
Total current assets	251,680	197,457
Long-term investments	33,602	7,992
Property and equipment, net	10,391	2,702
Prepaid expenses and other assets	3,116	4,210
Total assets	298,789	212,361
Current liabilities:
Accounts payable	1,427	1,863
Accrued liabilities	9,921	3,118
Other current liabilities	102	117
Total current liabilities	11,450	5,098
Other liabilities	1,367	1,012
Total liabilities	12,817	6,110
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, par value $0.0001 per share - 10,000 shares authorized at December 31, 2016 and 2015; 0 shares issued and outstanding at December 31, 2016 and 2015
Common stock, par value $0.0001 per share—290,000 shares authorized as of December 31, 2016 and 2015; 50,204 and 42,239 shares issued and outstanding as of December 31, 2016 and 2015, respectively (including 200 and 599 shares subject to repurchase, legally issued and outstanding as of December 31, 2016 and 2015, respectively)	5	4
Additional paid-in capital	420,151	259,668
Accumulated other comprehensive loss	(27)	(88)
Accumulated deficit	(134,157)	(53,333)
Total stockholders’ equity	285,972	206,251
Total liabilities and stockholders’ equity	$ 298,789	$ 212,361

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	290,000,000	290,000,000
Common stock, shares issued	50,204,000	42,239,000
Common stock, shares outstanding	50,204,000	42,239,000
Common Stock Subject to Repurchase
Common stock, shares issued	200,000	599,000
Common stock, shares outstanding	200,000	599,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating expenses
Research and development	$ 54,642,000	$ 19,816,000	$ 8,181,000
General and administrative	26,885,000	16,181,000	2,951,000
Total operating expenses	81,527,000	35,997,000	11,132,000
Loss from operations	(81,527,000)	(35,997,000)	(11,132,000)
Interest income, net	703,000	181,000	12,000
Loss before provision for income taxes	(80,824,000)	(35,816,000)	(11,120,000)
Provision for income taxes	0	0	0
Net loss	(80,824,000)	(35,816,000)	(11,120,000)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments	61,000	(88,000)	0
Comprehensive loss	$ (80,763,000)	$ (35,904,000)	$ (11,120,000)
Net loss per common share, basic and diluted	$ (1.89)	$ (1.88)	$ (3.80)
Weighted average shares used in computing net loss per share, basic and diluted	42,751	19,041	2,929

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated deficit
Beginning balance at Dec. 31, 2013	$ 11,637	$ 16,928			$ 1,106		$ (6,397)
Beginning balances (in shares) at Dec. 31, 2013		13,264		2,927
Issuance of common stock upon exercise of vested options	77				77
Issuance of common stock upon exercise of vested options (in shares)				1,325
Stock-based compensation	77				77
Other comprehensive gain (loss)	0
Net loss	(11,120)						(11,120)
Ending balances at Dec. 31, 2014	671	$ 16,928			1,260		(17,517)
Ending balances (in shares) at Dec. 31, 2014		13,264		4,252
Issuance of convertible preferred stock	79,779		$ 79,779
Issuance of convertible preferred stock (in shares)			14,048
Issuance of common stock upon exercise of vested options	303				303
Issuance of common stock upon exercise of vested options (in shares)				1,436
Issuance common stock upon initial public offering	168,119			$ 1	168,118
Issuance common stock upon initial public offering (in shares)				11,500
Repurchase of convertible preferred stock	(12,874)	$ (12,874)
Repurchase of convertible preferred stock (in shares)		(2,261)
Conversion of preferred stock to common stock		$ (4,054)	$ (79,779)	$ 3	83,830
Conversion of preferred stock to common stock (in shares)		(11,003)	(14,048)	25,051
Stock-based compensation	6,157				6,157
Other comprehensive gain (loss)	(88)					$ (88)
Net loss	(35,816)						(35,816)
Ending balances at Dec. 31, 2015	206,251			$ 4	259,668	(88)	(53,333)
Ending balances (in shares) at Dec. 31, 2015				42,239
Issuance of common stock upon exercise of vested options	2,843				2,843
Issuance of common stock upon exercise of vested options (in shares)				413
Issuance of common stock upon securities purchase agreement	145,000			$ 1	144,999
Issuance of common stock upon securities purchase agreement (in shares)				7,552
Stock-based compensation	12,641				12,641
Other comprehensive gain (loss)	61					61
Net loss	(80,824)						(80,824)
Ending balances at Dec. 31, 2016	$ 285,972			$ 5	$ 420,151	$ (27)	$ (134,157)
Ending balances (in shares) at Dec. 31, 2016				50,204

STATEMENTS OF STOCKHOLDERS' EQ6

STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - Series B Convertible Preferred Stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Feb. 28, 2015
Share price (per share)	$ 5.69	$ 5.69
Stock issuance costs	$ 221

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (80,824)	$ (35,816)	$ (11,120)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	534	115	29
Stock-based compensation	12,641	6,157	77
Investment premium amortization, net	919	324
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	3,967	(9,698)	10
Accounts payable	(994)	1,072	206
Accrued liabilities	6,803	1,859	1,021
Other liabilities	340	297
Net cash used in operating activities	(56,614)	(35,690)	(9,777)
Cash flows from investing activities:
Purchases of property and equipment	(7,665)	(1,708)	(56)
Purchases of investments	(197,178)	(152,811)
Maturities of investments	160,947	29,250
Change in restricted cash		40	(40)
Net cash used in investing activities	(43,896)	(125,229)	(96)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	145,000	168,119
Net cash proceeds from exercise of stock options, including early exercise	2,843	303	191
Net cash provided by financing activities	147,843	235,327	191
Net increase (decrease) in cash and cash equivalents	47,333	74,408	(9,682)
Cash and cash equivalents at the beginning of the period	76,677	2,269	11,951
Cash and cash equivalents at the end of the period	124,010	76,677	$ 2,269
Supplemental schedule of non-cash investing and financing activities:
Purchases of property and equipment reported in accounts payable	$ 558
Capital expenditures and interest funded through long term lease obligation		710
Series B Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance, net of issuance costs		79,779
Series A Convertible Preferred Stock
Cash flows from financing activities:
Repurchase of preferred stock		(12,874)
Initial Public Offering
Supplemental schedule of non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock at closing of initial public offering		$ 83,833

Formation and Business of the C

Formation and Business of the Company	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Formation and Business of the Company	1. Formation and Business of the Company Aimmune Therapeutics, Inc., or the Company, formerly known as Allergen Research Corporation, is a clinical-stage biopharmaceutical company advancing a new therapeutic approach, including the development of proprietary product candidates, for the treatment of peanut and other food allergies. Our therapeutic approach, which we refer to as Characterized Oral Desensitization Immunotherapy, or CODIT TM Since inception, we have incurred net losses and negative cash flows from operations. During the year ended December 31, 2016, we incurred a net loss of $80.8 million and used $56.6 million of cash in operations. As of December 31, 2016, we had an accumulated deficit of $134.2 million and we do not expect to experience positive cash flows in the near future. We have financed our operations to date primarily through private placements of our equity securities and our initial public offering, or IPO, of common stock in August 2015. Our ability to continue to meet our obligations and to achieve our business objectives is dependent upon a number of factors, which include raising additional capital, obtaining U.S. Food and Drug Administration, or FDA, and European Medicines Agency, or EMA, approval and commercializing in the United States and Europe, generating sufficient revenue and our ability to continue to control expenses, if necessary, to meet our obligations as they become due for the foreseeable future. Failure to obtain FDA and EMA approval, commercialize our lead product candidate, manage discretionary expenditures or raise additional financing, as required, may adversely impact our ability to achieve our intended business objectives. As of December 31, 2016, we had cash, cash equivalents and investments of $282.5 million. We believe that our existing capital resources will be sufficient to fund our planned operations for at least the next 12 months and through regulatory submissions for AR101, our lead investigational biologic oral immunotherapy for desensitization of patients with peanut allergy. Private Placement On November 23, 2016, we completed the issuance and sale of 7,522,084 shares of our common stock for an aggregate cash purchase price of $145.0 million, or the Equity Investment, pursuant to a Securities Purchase Agreement, or the Purchase Agreement, dated November 2, 2016, by and between us and Nestle Health Science US Holdings, Inc., a Delaware corporation, or Nestle Health Science. In connection with the closing of the Equity Investment, we and Nestle Health Science entered into a Standstill Agreement, or the Standstill Agreement, and a Registration Rights Agreement, or the Registration Rights Agreement. See Note 6, “Stockholders’ Equity.” Initial Public Offering On August 5, 2015, our registration statement on Form S-1 (File No. 333-205501) relating to the IPO of our common stock became effective. The IPO closed on August 11, 2015 at which time we issued 11,499,999 shares of our common stock at a price of $16.00 per share, which included 1,499,999 shares sold pursuant to the exercise in full of the underwriters’ option to purchase additional shares. We received proceeds of approximately $168.1 million, net of underwriting discounts and commissions, and offering expenses. In addition, upon our IPO, all outstanding shares of convertible preferred stock converted by their terms into approximately 25.1 million shares of common stock. As of December 31, 2016, we had 50,204,383 shares of common stock outstanding. See Note 6, “Stockholders’ Equity.” Stock Split On July 30, 2015, we effected a 1-for-1.317 stock split of our common stock and convertible preferred stock. The par value of the authorized stock was not adjusted as a result of the stock split. In addition, we increased the number of authorized shares of common stock to 55,051,264 and the number of authorized shares of preferred stock to 25,051,264. All issued and outstanding common stock, convertible preferred stock, stock options and per share amounts contained in the accompanying consolidated financial statements and accompanying notes have been retroactively adjusted to give effect to the stock split for all periods presented. In conjunction with the our IPO, we filed our amended and restated certificate of incorporation that authorized 290,000,000 shares of common stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share.

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 Basis of Preparation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP, and include the accounts of our wholly-owned subsidiaries. All significant intercompany transactions have been eliminated. We operate in one reportable segment in the United States. Foreign Currency Translation Our functional currency and the functional currency of all of our subsidiaries is the United States dollar. Accordingly, monetary assets and liabilities in the non-functional currency of these subsidiaries are remeasured using exchange rates in effect at the end of the period. Costs in local currency are remeasured using average exchange rates for the period, except for costs related to those balance sheet items that are remeasured using historical exchange rates. The resulting remeasurement gains and losses are included in the consolidated statements of operations and comprehensive loss as incurred and have not been material for all periods presented. Use of Estimates The preparation of the accompanying consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of costs and expenses during the reporting period. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions. Cash and Cash Equivalents We consider all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents, which are carried at estimated fair value, consist primarily of money market funds and certain available-for-sale investments with maturities of three months or less. 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. We have one operating segment. Concentration of Credit Risk Financial instruments that potentially subject us to a concentration of credit risk consist of cash and cash equivalents and certain investments in money market funds, agency securities, corporate securities, U.S. government securities and commercial paper. Bank deposits are primarily held by a single financial institution and these deposits may exceed insured limits. We are exposed to credit risk in the event of default by the financial institution holding our cash and cash equivalents and issuers of investments that are recorded on our consolidated balance sheets. We mitigate our risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits our exposure. Investments Our investments consist of available-for-sale securities. Investments with original maturities of greater than 90 days but less than one (1) year are classified as short-term on the consolidated balance sheets. Investments with original maturities greater than one (1) year are classified as long-term on the consolidated balance sheets. Our investments in available-for-sale securities are reported at estimated fair value. Available-for-sale securities consist primarily of agency securities, corporate securities, U.S. government securities and commercial paper. Unrealized gains and losses related to changes in the fair value of securities are recognized in accumulated other comprehensive loss, net of tax, on our consolidated balance sheets. Changes in the fair value of available-for-sale securities impact the consolidated statements of operations and comprehensive loss only when such securities are sold or an other-than-temporary impairment is recognized. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We regularly review our investment portfolio to determine if any security is other-than-temporarily impaired, which would require us to record an impairment charge in the period any such determination is made. We consider factors such as the duration, severity and the reason for the decline in value, the financial condition of the issuer and any changes thereto, the potential recovery period and our intent to sell. For debt securities, we also consider whether (i) it is more likely than not that we will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. Our assessment on whether a security is other-than-temporarily impaired could change in the future due to new developments or changes in assumptions related to any particular security. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets. Maintenance and repairs are charged to the consolidated statements of operations and comprehensive loss as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss, if any, is reflected in the consolidated statements of operations and comprehensive loss. The useful lives of property and equipment are as follows: Furniture and office equipment 4 years Computer equipment 3 years Buildings 25 years Fixtures 10 years Impairment of Long-Lived Assets We evaluate our long-lived assets, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows expected to result from the use of the asset and its eventual disposition. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired assets. We have not recorded impairment of any long-lived assets in the periods presented. Leases Leases related to our corporate headquarters are classified as operating leases. Rent expense is recognized on a straight-line basis over the terms of the leases and, accordingly, we record the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Incentives granted under facilities leases are deferred and recognized as adjustments to rental expense on a straight-line basis over the term of the lease. In June 2015, we signed a lease for a manufacturing facility in Clearwater, Florida. We were considered the deemed owner for accounting purposes. See Note 5, “Commitments and Contingencies,” for further details. Research and Development We expense research and development costs as incurred. We record accrued liabilities for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials and contract manufacturing activities. These costs are a significant component of our research and development expenses. We accrue for these costs based on factors such as estimates of the work completed and in accordance with agreements established with our third-party service providers under the service agreements. We make significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled and the rate of patient enrollments may vary from our estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in material changes to our accruals could materially affect our results of operations. Stock-Based Compensation Stock-based awards issued to employees, including stock options, are measured at fair value on the grant date using the Black-Scholes option-pricing model and recognized as expense on a straight-line basis over the employee’s requisite service period (generally the vesting period). Because noncash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. There were 2,343,385, 4,192,485 and 1,635,681 stock options granted during the years ended December 31, 2016, 2015 and 2014, respectively. Additionally, there were 17,000, 0, and 0 restricted stock units awarded during the years ended December 31, 2016, 2015 and 2014 respectively. Income Taxes We use the asset and 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 reported 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. We 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. Due to our lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance. Comprehensive Income or Loss Comprehensive income or loss is defined as the change in equity during a period from transactions and other events, excluding changes resulting from investments from owners and distributions to owners. Other comprehensive loss includes net loss and unrealized gains and losses on available-for-sale investments. Net Loss per Share The following common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because their inclusion would have been antidilutive: Year Ended December 31, 2016 2015 2014 Series A convertible preferred stock — — 13,263,967 Stock options 5,429,267 4,814,892 2,566,559 Restricted stock units 17,000 — — Offering Costs Offering costs represent underwriting, legal, accounting and other direct costs related to our IPO. These costs were deferred until completion of the IPO, at which time they were reclassified to additional paid-in capital as a reduction of the proceeds. Fair Value Measurements We define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Our valuation techniques are based on observable and unobservable inputs. Observable inputs reflect readily obtainable data from independent sources, while unobservable inputs reflect our market assumptions. We classify these inputs into the following hierarchy: Level 1 —Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 —Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 —Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. Financial instruments include cash equivalents, investments, accounts payable, and accrued liabilities. Our cash equivalents and investments are carried at estimated fair value and remeasured on a recurring basis. The carrying value of accounts payable and accrued liabilities approximate their estimated fair value due to the relatively short-term nature of these instruments. Our valuation techniques used to measure the fair value of money market funds were derived from quoted prices in active markets for identical assets. The valuation techniques used to measure the fair value of investments, all of which have counterparties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. In accordance with fair value accounting requirements, companies may choose to measure eligible financial instruments and certain other items at fair value. We have not elected the fair value option for any eligible financial instruments. Recently Issued Accounting Pronouncements Not Yet Adopted In November 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-18, Statement of Cash Flows – Restricted Cash (Topic 230) In October 2016, the FASB, issued ASU, 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers Other Than Inventory In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In March 2016, the FASB, issued ASU 2016-09, Compensation—Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting , which simplifies several aspects of accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities, classification on the statement of cash flows and accounting for forfeitures. The new standard is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years with early adoption permitted. We do not expect the adoption of this new standard to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB, issued ASU, No. 2016-02, Leases (Topic 842) Reclassifications Certain amounts in the prior years have been reclassified in order to conform to the current year’s presentation. None of the reclassifications impacted the results of our operations in any of the years presented.

Available-for-Sale Securities a

Available-for-Sale Securities and Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Available-for-Sale Securities and Fair Value Measurements	3. Available-for-Sale Securities and Fair Value Measurements The following table sets forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Cash and cash equivalents: Cash and money market funds $ 107,977 $ — $ — $ 107,977 Commercial paper — 16,033 — 16,033 Total cash and cash equivalents $ 107,977 $ 16,033 $ — $ 124,010 Investments: Agency securities — 45,571 — 45,571 Corporate securities — 22,031 — 22,031 Commercial paper — 8,669 — 8,669 US government securities — 82,252 — 82,252 Total investments $ — $ 158,523 $ — $ 158,523 December 31, 2015 Level 1 Level 2 Level 3 Total Cash and cash equivalents: Cash and money market funds $ 61,477 $ — $ — $ 61,477 Agency securities — 9,701 — 9,701 Corporate securities — 2,000 — 2,000 Commercial paper — 3,499 — 3,499 Total cash and cash equivalents $ 61,477 $ 15,200 $ — $ 76,677 Investments: Certificates of deposit $ 100 $ — $ — $ 100 Agency securities — 43,325 — 43,325 Corporate securities — 49,596 — 49,596 Commercial paper — 17,843 — 17,843 US government securities — 12,286 — 12,286 Total investments $ 100 $ 123,050 $ — $ 123,150 Available-for-sale investments are carried at fair value and are included in the tables above. The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents and investments, as of December 31, 2016 are as follows (in thousands): December 31, 2016 Amortized Cost Gross unrealized gains Gross unrealized losses Total fair value Agency securities $ 45,591 $ 5 $ (25 ) $ 45,571 Corporate securities 22,050 2 (21 ) 22,031 Commercial paper 24,702 — — 24,702 US government securities 82,240 15 (3 ) 82,252 Total available-for-sale investments $ 174,583 $ 22 $ (49 ) $ 174,556 The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents and investments, as of December 31, 2015 are as follows (in thousands): December 31, 2015 Amortized Cost Gross unrealized gains Gross unrealized losses Total fair value Agency securities $ 53,062 $ 2 $ (38 ) $ 53,026 Corporate securities 51,626 28 (58 ) 51,596 Commercial paper 21,342 — — 21,342 US government securities 12,308 — (22 ) 12,286 Total available-for-sale investments $ 138,338 $ 30 $ (118 ) $ 138,250 There were no gross realized gains or losses on sales of available-for-sale securities for the years ended December 31, 2016, 2015, and 2014. Expected maturities will differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties. We did not identify any other-than-temporary losses for the years ended December 31, 2016, 2015 and 2014. We do not consider unrealized losses on our other debt securities to be credit-related. These unrealized losses relate to changes in interest rates and market spreads subsequent to purchase. A substantial portion of securities that have unrealized losses are US corporate securities that are highly-rated. We have not made a decision to sell securities with unrealized losses and believe it is more likely than not we would not be required to sell such securities before recovery of its amortized cost.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, Net Property and equipment, net consists of the following (in thousands): Year Ended December 31, 2016 2015 Furniture and equipment $ 776 $ 220 Computer equipment 850 324 Manufacturing equipment 703 458 Construction in progress 8,749 1,853 Property and equipment, gross 11,078 2,855 Less: accumulated depreciation (687 ) (153 ) Property and equipment, net $ 10,391 $ 2,702 Depreciation expense for the years ended December 31, 2016, 2015 and 2014 was $0.5 million, $0.1 million and $0.0 million, respectively. Accrued Liabilities Accrued liabilities consist of the following (in thousands): Year Ended December 31, 2016 2015 Compensation and benefits $ 3,195 $ 1,645 Research and development 5,154 972 Professional and consulting 967 381 Other 605 120 Total accrued liabilities $ 9,921 $ 3,118

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and Contingencies Facility Leases In March 2015, we entered into a new lease for our corporate headquarters in Brisbane, California for 11,665 square feet of office space. Upon the commencement of the new lease in May 2015, we ceased use of our previous corporate headquarters. In August 2015, we entered into an amendment to the Brisbane, California facility lease. Pursuant to the amendment, we leased an additional 26,355 square feet of office space. The term for the new space is 72 months from the delivery of the premises to us, which took place December 2015. In addition, the term of the existing office space has been extended so that it is coterminous with the new space. The amendment required a total security deposit of approximately $0.3 million. We are responsible for operating expenses over base operating expenses as defined in the headquarters lease agreement. In June 2015, we signed a facility lease for a manufacturing facility for approximately 20,000 square feet of manufacturing space in Clearwater, Florida. The initial term of the lease is for 120 months. For accounting purposes, due to the nature and extent of our involvement with the construction of this manufacturing facility, we were considered to be the owner of the assets during the construction period through the lease commencement date, even though the lessor is responsible for funding and repairing components of the building shell and constructing a portion of the related building infrastructure. Construction to this building commenced in July 2015 and as of December 31, 2016, we have incurred approximately $0.3 million of construction and equipment costs related to the building, which is recorded in construction in progress. We also recorded $0.7 million to construction in progress for costs incurred by the lessor and recognized a corresponding amount included within other liabilities within the consolidated balance sheet. We are responsible for operating expenses including real estate taxes as defined in the manufacturing facility lease agreement. Total future aggregate minimum lease payments under our operating leases are as follows (in thousands): Year Ended December 31, 2017 $ 2,216 2018 1,919 2019 1,905 2020 1,980 2021 1,872 and after 691 Total $ 10,583 Rent expense under operating leases for the years ended December 31, 2016, 2015 and 2014 was $1.7 million, $0.6 million and $0.1 million, respectively. Capital Lease In July 2016, we entered into a five year capital lease agreement for certain equipment in our Florida manufacturing facility. The current portion of the capital lease obligation is included in Other Current Liabilities and the noncurrent portion is included in Other Liabilities. The following is a schedule of future minimum lease payments due under the capital lease obligation as of December 31, 2016 (in thousands): Year Ended December 31, 2017 $ 33 2018 33 2019 34 2020 35 2021 26 Total capital lease obligation 161 Less: amount representing interest 64 Present value of net minimum capital lease payments 97 Less: current portion 12 Total noncurrent capital lease obligation $ 85 Purchase Commitments We purchase peanut flour, the source material for AR101, from the Golden Peanut Company pursuant to a long term exclusive commercial supply agreement. Pursuant to the agreement, our purchase obligation commences with the first delivery of peanut flour for commercial use, which we currently anticipate will not occur prior to 2018. Assuming that our first delivery for commercial use occurs in 2018, which is not assured, the aggregate purchase commitment under this agreement would be $1.2 million over a term of five years. Indemnifications We indemnify each of our officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with our certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or a director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity. The maximum amount of potential future indemnification is unlimited; however, we currently hold directors and officers liability insurance. This insurance allows the transfer of risk associated with our exposure and may enable us to recover a portion of any future amounts paid. We believe that the fair value of these indemnification obligations is minimal. Accordingly, we have not recognized any liabilities relating to these obligations for any period. Legal During the normal course of business, we may be a party to legal claims that may not be covered by insurance. We do not believe that any such claims would have a material impact on our consolidated financial statements.

Stockholders_ Equity

Stockholders’ Equity	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders’ Equity	6. Stockholders’ Equity Convertible Preferred Stock In January and February 2015, we issued an aggregate 14,047,996 shares of Series B convertible preferred stock, $0.0001 par value, original issue price of $5.69 per share, for gross cash proceeds of $80.0 million, and in January 2015, we repurchased 2,260,706 shares of Series A convertible preferred stock from certain investors. The purchase price of the Series A convertible preferred stock was $5.69 per share, the same as the issue price of the Series B convertible stock, and was at an aggregate cost of $12.9 million. The offering costs for the issuance and sale of Series B convertible preferred stock was $221,000. All 25,051,257 shares of our then-outstanding convertible preferred stock converted into an equivalent number of shares of common stock upon the closing of our IPO on August 11, 2015. As of December 31, 2016 and 2015, we had authorized 10,000,000 shares of convertible preferred stock, and no shares of convertible preferred stock were issued and outstanding. Common Stock On November 23, 2016, we issued and sold 7,522,084 shares of our common stock, par value $0.0001 per share, for an aggregate cash purchase price of $145.0 million, pursuant to the Purchase Agreement, dated November 2, 2016, by and between us and Nestle Health Science. In connection with the closing of the Equity Investment, we and Nestle Health Science entered into a Registration Rights Agreement and a Standstill Agreement. Under the terms of the Registration Rights Agreement, upon the written request of Nestle Health Science, we shall prepare and file with the Securities and Exchange Commission, or the Commission, a registration statement covering the resale of all the shares sold to Nestle Health Science that are not then registered on an existing and effective registration statement for an offering to be made on a continuous basis pursuant Commission Rule 415. Additionally, we shall use commercially reasonable efforts to cause such registration statement filed under the Registration Rights Agreement to be declared effective under the Securities Act of 1933, as amended, within certain defined time limits and to keep such registration statement continuously effective for a period of potentially three years from the original effect date of such registration statement. Under the terms of the Standstill Agreement, Nestle Health Science is prohibited from entering into transactions with the shares purchased in the Equity Investment, as well as to enter into any transactions with any of our assets, without prior written consent of a majority of the members of our board of directors until the later of the end of the term of the Collaboration Agreement and November 23, 2018.

Stock-based Awards

Stock-based Awards	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Awards	7. Stock-Based Awards Equity Plans In July 2015, we adopted the 2015 Stock Plan, or the 2015 Plan. Under the 2015 Plan, 4,681,544 shares of our common stock were initially reserved for the issuance of stock options and restricted stock to employees, directors, and consultants under terms and provisions established by the Board of Directors, or the Board, and approved by our stockholders. As of December 31, 2016 and December 31, 2015 there were 4,344,487 and 4,443,479 and shares available for future grant, respectively. Under the terms of the 2015 Plan, options may be granted at an exercise price not less than fair market value. For employees holding more than 10% of the voting rights of all classes of stock, the exercise prices for incentive stock options may not be less than 110% of fair market value, as determined by the Board. The terms of options granted under the 2015 Plan may not exceed ten years. All options issued to date have had a ten-year life. To date, options granted generally vest in three ways: 1) over four years at a rate of 25% upon the first anniversary of the issuance date and 1/48 th th th Our 2013 Stock Plan, or the 2013 Plan, which was originally adopted during January 2013, was terminated upon consummation of our IPO in August 2015. As a terminated plan, no further options can be granted from the 2013 Plan, and no further shares are reserved for issuance under the 2013 Plan. Prior to its termination, the 2013 Plan allowed employees to exercise a stock option in exchange for cash before the requisite service is provided (e.g., before the award is vested under its original terms); however, such arrangements permit us to subsequently repurchase such shares at the exercise price if the vesting conditions are not satisfied. Such an exercise is not substantive for accounting purposes. Therefore, the payment received by us for the exercise price is recognized as an early exercise liability on the consolidated balance sheets and will be transferred to common stock and additional paid-in capital as such shares vest. As of December 31, 2016 and December 31, 2015, 199,538 and 599,242 unvested shares were legally issued and outstanding, respectively. In connection with these unvested shares, we have recorded an early exercise liability as of December 31, 2016 and 2015 of $0.06 million and $0.22 million, respectively, of which $0.05 million and $0.14 million is included in other current liabilities as of December 31, 2016 and 2015, respectively, and $0.01 million $0.08 million is included in other liabilities as of December 31, 2016 and 2015, respectively, in the consolidated balance sheets. These shares are excluded from basic and diluted net loss per share until our repurchase right lapses and the shares are no longer subject to the repurchase feature. Activity under the 2015 Plan and 2013 Plan is set forth below: Options Outstanding Number Options and Unvested Shares Weighted- Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Balance, December 31, 2015 4,814,892 $ 5.20 9.23 $ 64,211 Options granted 2,343,385 $ 16.02 Options exercised and shares vested (813,102 ) $ 3.49 Options repurchased (68,150 ) $ 0.14 Options cancelled (648,118 ) $ 9.64 Balance, December 31, 2016 5,628,907 $ 9.50 9.02 $ 61,617 Options vested and expected to vest as of December 31, 2016 5,422,307 $ 9.41 8.68 $ 59,856 Options exercisable as of December 31, 2016 3,344,876 $ 2.96 8.66 $ 51,749 The aggregate intrinsic values of options outstanding, exercisable, and vested and expected to vest were calculated as the difference between the exercise price of the options and the market price for shares of our common stock as of December 31, 2016. The 2013 Plan provided for early exercise, therefore, all the Company’s outstanding stock options issued under that plan are exercisable. The total intrinsic value of options exercised during the year ended December 31, 2016 was $6.5 million. Stock Options Granted Stock options granted during the years ended December 31, 2016, 2015, and 2014 had a per share weighted-average grant-date fair value of $10.53, $6.11 and $0.09, respectively. The fair value is being expensed over the vesting period of the options, which is either four years or two years on a straight-line basis as the services are being provided. No tax benefits were realized from options during the periods. We issued one grant totaling 213,354 options to a non-employee during the year ended December 31, 2015. The fair value of the non-employee options was measured using the Black-Scholes option-pricing model reflecting the same assumptions as applied to employee options, other than the expected life, which was assumed to be the remaining contractual life of the option. During 2016, we converted the non-employee to an employee, and converted the grant from a non-employee grant to an employee grant. The conversion of the grant was treated as a modification of the original grant; accordingly, we recognized $0.09 million of modification expense. As of December 31, 2016 and 2015, total unrecognized stock-based compensation expense was $27.3 million and $17.2 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.72 years and 3.23 years, respectively. Restricted stock unit, or RSU, activity under the 2015 Plan is set forth below: Shares Weighted Grant Date Fair Value Unvested Balance, December 31, 2015 — $ — Awarded 17,000 14.01 Released — — Forfeited — — Unvested Balance, December 31, 2016 17,000 $ 14.01 RSUs are measured based on the fair market value of the underlying stock on the date of grant and recognized as expense on a straight-line basis over the employee’s requisite service period (generally the vesting period). As of December 31, 2016, there was $0.1 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 0.2 years. Determining Fair Value of Stock Options Prior to our IPO, the fair value of our shares of common stock underlying the stock options was the responsibility of and determined by our Board. Because there was no public market for our common stock, the Board determined the fair value of common stock at the time of grant of the option by considering a number of objective and subjective factors, including independent third-party valuations of our common stock, sales of convertible preferred stock to unrelated third parties, operating and financial performance, the lack of liquidity of capital stock and general and industry specific economic outlook, amongst other factors. Following the IPO, the market traded price of the shares of common stock underlying the stock options is the closing price of our stock as reported on The NASDAQ Global Select Market on the grant date. In determining the fair value of the stock-based awards used to calculate stock-based compensation expense, we use the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine. • Expected Term. The expected term of stock options represents the weighted average period the stock options are expected to be outstanding. We have opted to use the simplified method for estimating the expected term as provided by the Securities and Exchange Commission Staff Accounting Bulletin, SAB, 110 as our options grants are considered “plain vanilla”. The simplified method calculates the expected term as the average time- to-vesting and the contractual life of the options. We plan to continue to use the simplified method under SAB 110 until we have sufficient exercise history as a publicly traded company. • Expected Volatility. The expected stock price volatility assumption was determined by examining the historical volatilities of a group of industry peers, as we have limited trading history for our common stock. Industry peers consist of several public companies in the biopharmaceutical industry with comparable characteristics including enterprise value, risk profiles and position within the industry. We intend to continue to consistently apply this process using the same or similar public companies until a sufficient amount of historical information regarding the volatility of our own common stock share price becomes available, or unless circumstances change such that the identified companies are no longer similar to us, in which case, more suitable companies whose share prices are publicly available would be utilized in the calculation. • Risk-Free Interest Rate. The risk-free interest rate is based on the Black-Scholes valuation model on the implied yield available on U.S. Treasury zero-coupon issues in effect at the time of grant for periods corresponding with the expected term of the option. Expected Dividend Yield. We have never paid dividends on our common stock and have no plans to pay dividends on our common stock. Therefore, we used an expected dividend yield of zero. The following table presents the weighted-average assumptions used to estimate the fair value of options granted: Year Ended December 31, 2016 2015 2014 Expected volatility 74.46 % 74.14 % 79.62 % Risk-free interest rate 1.71 % 1.73 % 1.51 % Expected dividend yield — — — Expected term (in years) 6.03 5.99 4.65 Weighted average grant date fair value $ 10.53 $ 6.11 $ 0.09 Stock-based compensation expense, net of estimated forfeitures, is reflected in the statements of operations and comprehensive loss (in thousands) as summarized below: Year Ended December 31, 2016 2015 2014 Research and development $ 4,838 $ 2,522 $ 23 General and administrative 7,803 3,635 54 Total stock-based compensation expense $ 12,641 $ 6,157 $ 77 During the years ended December 31, 2016, 2015 and 2014, we recorded $0.9 million, $1.4 million and $0 of stock compensation expense related to the acceleration of certain former executives’ stock options, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes We did not record a tax provision for the years ended December 31, 2016, 2015 and 2014 as we incurred net losses in each period, and the need for a full valuation allowance on deferred tax assets. The following table presents loss before provision for income taxes (in thousands): Year Ended December 31, 2016 2015 2014 Income/(loss) before income taxes Domestic $ (66,210 ) $ (17,489 ) $ (11,120 ) Foreign (14,614 ) (18,327 ) — Total loss before provision for income taxes $ (80,824 ) $ (35,816 ) $ (11,120 ) Income tax expense for the years ended December 31, 2016, 2015 and 2014 differed from the amount expected by applying the statutory federal tax rate to the loss before taxes as summarized below (in thousands): Year Ended December 31, 2016 2015 2014 Federal tax benefit at statutory rate 34.00 % 34.00 % 34.00 % State tax benefit, net of federal benefit 0.39 % 3.02 % 6.33 % Stock compensation -1.75 % -1.59 % 0.00 % Change in valuation allowance -27.45 % -20.55 % -41.23 % Research and development credits 2.53 % 2.52 % 1.08 % Foreign income taxed at different rates -6.13 % -17.40 % 0.00 % Other -1.59 % 0.00 % -0.18 % Income tax expense 0.00 % 0.00 % 0.00 % The significant components of our deferred taxes are as follows (in thousands): Year Ended December 31, 2016 2015 Deferred tax assets (liabilities): Net operating loss carryforwards $ 27,109 $ 9,857 Start-up costs 1,282 1,612 Stock-based compensation 3,427 1,413 Tax credit carryforwards 3,585 1,296 Accruals 1,041 195 Other 22 (2 ) Total deferred tax assets 36,466 14,371 Less: valuation allowance (36,466 ) (14,371 ) Net deferred income taxes $ — $ — We recognize deferred income taxes for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. We periodically evaluate the positive and negative evidence bearing upon realizability of our deferred tax assets. Based upon the weight of available evidence, which includes our historical operating performance, reported cumulative net losses since inception and difficulty in accurately forecasting our future results, we maintained a full valuation allowance on the net deferred tax assets as of December 31, 2016 and 2015. We intend to maintain a full valuation allowance on the federal and state deferred tax assets until sufficient positive evidence exists to support reversal of the valuation allowance. The net change in the valuation allowance for the years ended December 31, 2016 and December 31, 2015 was an increase of $22.1 million and $7.4 million, respectively. As of December 31, 2016, we had net operating loss, or NOL, carryforwards for Federal, California and other state income tax purposes of $81.0 million, $12.0 million, and $2.4 million, respectively. As of December 31, 2015, we had NOL carryforwards for Federal, California and other state income tax purposes of $24.7 million, $12.0 million, and $0.4 million, respectively, which will begin to expire in 2031, 2031, and 2030, respectively, if not utilized. $3.6 million, $0.0 million, and $0.1 million of the Federal, California, and other state NOL carryforwards, respectively, relates to windfall stock option deductions, which, when we adopt ASU 2016-09, will increase our NOL carryforwards deferred tax assets and our valuation allowance. At December 31, 2016 and 2015, we had Federal and California research credit carryforwards of $3.9 million and $0.9 million, respectively. The Federal research credits will begin to expire in 2032, while the California research credits have no expiration date. Our ability to utilize NOL carryforwards or other tax attributes, such as research tax credits, in any taxable year may be limited if we have experienced an ownership change under Section 382 of the Internal Revenue Code of 1986, as amended, or the Code. Following issuance of the Series B convertible preferred stock in January and February 2015, we performed a preliminary Section 382 analysis and believe that we experienced multiple ownership changes prior to June 30, 2015, and, as a result, such federal and state NOL carryforwards and our tax credits are subject to limitation. We have not performed a Section 382 analysis to evaluate whether or not we experienced an ownership change as a result of either our August 2015 IPO or the November 2016 Equity Investment by Nestle Health Science. Tax benefits from uncertain tax positions are recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on technical merits. The amount recognized is measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon effective settlement. The following table summarizes the activity related to our unrecognized benefits (in thousands): Year Ended December 31, 2016 2015 Beginning balance - unrecognized tax benefit, gross $ — $ — Increases related to tax positions taken during a prior year — — Decreases related to a tax position taken during a prior year — — Increases related to tax positions taken during the current year 960 — Decreases related to settlements with taxing authorities — — Decreases related to expiration of statute of limitations — — Ending balance - unrecognized tax benefits, gross $ 960 $ — At December 31, 2016, the unrecognized tax benefits for uncertain tax positions were offset against the deferred tax assets and would not affect the income tax rate if recognized due to our being in a valuation allowance position. Our policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for taxes in the consolidated statements of operations. We did not accrue any interest or penalties for the years ended December 31, 2016 and 2015. We do not have any tax positions for which it is reasonably possible that the total amount of gross unrecognized tax benefits will significantly change within 12 months of December 31, 2016. We file federal, state and foreign income tax returns in jurisdictions with varying statutes of limitations. Due to our NOL carryforwards, our income tax returns remain subject to examination by federal and most state taxing authorities for all tax years.

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	9. Defined Contribution Plan We sponsor a 401(k) Plan, or the 401(k) Plan, which stipulates that eligible employees may contribute to the 401(k) Plan subject to certain limitations. We may match employee contributions in amounts to be determined at our sole discretion. To date, we have not made any matching contributions.

Selected Quarterly Results of O

Selected Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Results of Operations (Unaudited)	10. Selected Quarterly Results of Operations (Unaudited) The following table presents our unaudited quarterly financial data. Our quarterly results of operations for these periods are not necessarily indicative of our future results of operations. Quarter Ended March 31 June 30 September 30 December 31 2016 (In thousands, except per share data) Operating expenses: Research and development $ 9,976 $ 11,820 $ 15,888 $ 16,958 General and administrative 5,723 6,466 6,353 8,343 Total operating expenses 15,699 18,286 22,241 25,301 Loss from operations (15,699 ) (18,286 ) (22,241 ) (25,301 ) Interest income, net 176 147 155 225 Net loss $ (15,523 ) $ (18,139 ) $ (22,086 ) $ (25,076 ) Net loss per common share, basic and diluted $ (0.37 ) $ (0.43 ) $ (0.53 ) $ (0.55 ) Quarter Ended March 31 June 30 September 30 December 31 2015 (In thousands, except per share data) Operating expenses: Research and development $ 2,069 $ 3,131 $ 3,850 $ 10,766 General and administrative 1,372 4,246 5,174 5,389 Total operating expenses 3,441 7,377 9,024 16,155 Loss from operations (3,441 ) (7,377 ) (9,024 ) (16,155 ) Interest income, net — 1 33 147 Net loss $ (3,441 ) $ (7,376 ) $ (8,991 ) $ (16,008 ) Net loss per common share, basic and diluted $ (0.81 ) $ (1.60 ) $ (0.36 ) $ (0.39 )

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Preparation	Basis of Preparation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP, and include the accounts of our wholly-owned subsidiaries. All significant intercompany transactions have been eliminated. We operate in one reportable segment in the United States.
Foreign Currency Translation	Foreign Currency Translation Our functional currency and the functional currency of all of our subsidiaries is the United States dollar. Accordingly, monetary assets and liabilities in the non-functional currency of these subsidiaries are remeasured using exchange rates in effect at the end of the period. Costs in local currency are remeasured using average exchange rates for the period, except for costs related to those balance sheet items that are remeasured using historical exchange rates. The resulting remeasurement gains and losses are included in the consolidated statements of operations and comprehensive loss as incurred and have not been material for all periods presented.
Use of Estimates	Use of Estimates The preparation of the accompanying consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of costs and expenses during the reporting period. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents, which are carried at estimated fair value, consist primarily of money market funds and certain available-for-sale investments with maturities of three months or less.
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. We have one operating segment.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject us to a concentration of credit risk consist of cash and cash equivalents and certain investments in money market funds, agency securities, corporate securities, U.S. government securities and commercial paper. Bank deposits are primarily held by a single financial institution and these deposits may exceed insured limits. We are exposed to credit risk in the event of default by the financial institution holding our cash and cash equivalents and issuers of investments that are recorded on our consolidated balance sheets. We mitigate our risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits our exposure.
Investments	Investments Our investments consist of available-for-sale securities. Investments with original maturities of greater than 90 days but less than one (1) year are classified as short-term on the consolidated balance sheets. Investments with original maturities greater than one (1) year are classified as long-term on the consolidated balance sheets. Our investments in available-for-sale securities are reported at estimated fair value. Available-for-sale securities consist primarily of agency securities, corporate securities, U.S. government securities and commercial paper. Unrealized gains and losses related to changes in the fair value of securities are recognized in accumulated other comprehensive loss, net of tax, on our consolidated balance sheets. Changes in the fair value of available-for-sale securities impact the consolidated statements of operations and comprehensive loss only when such securities are sold or an other-than-temporary impairment is recognized. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We regularly review our investment portfolio to determine if any security is other-than-temporarily impaired, which would require us to record an impairment charge in the period any such determination is made. We consider factors such as the duration, severity and the reason for the decline in value, the financial condition of the issuer and any changes thereto, the potential recovery period and our intent to sell. For debt securities, we also consider whether (i) it is more likely than not that we will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. Our assessment on whether a security is other-than-temporarily impaired could change in the future due to new developments or changes in assumptions related to any particular security.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets. Maintenance and repairs are charged to the consolidated statements of operations and comprehensive loss as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss, if any, is reflected in the consolidated statements of operations and comprehensive loss. The useful lives of property and equipment are as follows: Furniture and office equipment 4 years Computer equipment 3 years Buildings 25 years Fixtures 10 years
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We evaluate our long-lived assets, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows expected to result from the use of the asset and its eventual disposition. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired assets. We have not recorded impairment of any long-lived assets in the periods presented.
Leases	Leases Leases related to our corporate headquarters are classified as operating leases. Rent expense is recognized on a straight-line basis over the terms of the leases and, accordingly, we record the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Incentives granted under facilities leases are deferred and recognized as adjustments to rental expense on a straight-line basis over the term of the lease. In June 2015, we signed a lease for a manufacturing facility in Clearwater, Florida. We were considered the deemed owner for accounting purposes. See Note 5, “Commitments and Contingencies,” for further details.
Research and Development	Research and Development We expense research and development costs as incurred. We record accrued liabilities for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials and contract manufacturing activities. These costs are a significant component of our research and development expenses. We accrue for these costs based on factors such as estimates of the work completed and in accordance with agreements established with our third-party service providers under the service agreements. We make significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled and the rate of patient enrollments may vary from our estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in material changes to our accruals could materially affect our results of operations.
Stock-based Compensation	Stock-Based Compensation Stock-based awards issued to employees, including stock options, are measured at fair value on the grant date using the Black-Scholes option-pricing model and recognized as expense on a straight-line basis over the employee’s requisite service period (generally the vesting period). Because noncash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. There were 2,343,385, 4,192,485 and 1,635,681 stock options granted during the years ended December 31, 2016, 2015 and 2014, respectively. Additionally, there were 17,000, 0, and 0 restricted stock units awarded during the years ended December 31, 2016, 2015 and 2014 respectively.
Income Taxes	Income Taxes We use the asset and 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 reported 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. We 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. Due to our lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.
Comprehensive Income or Loss	Comprehensive Income or Loss Comprehensive income or loss is defined as the change in equity during a period from transactions and other events, excluding changes resulting from investments from owners and distributions to owners. Other comprehensive loss includes net loss and unrealized gains and losses on available-for-sale investments.
Net Loss per Share	Net Loss per Share The following common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because their inclusion would have been antidilutive: Year Ended December 31, 2016 2015 2014 Series A convertible preferred stock — — 13,263,967 Stock options 5,429,267 4,814,892 2,566,559 Restricted stock units 17,000 — —
Offering Costs	Offering Costs Offering costs represent underwriting, legal, accounting and other direct costs related to our IPO. These costs were deferred until completion of the IPO, at which time they were reclassified to additional paid-in capital as a reduction of the proceeds.
Fair Value Measurements	Fair Value Measurements We define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Our valuation techniques are based on observable and unobservable inputs. Observable inputs reflect readily obtainable data from independent sources, while unobservable inputs reflect our market assumptions. We classify these inputs into the following hierarchy: Level 1 —Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 —Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 —Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. Financial instruments include cash equivalents, investments, accounts payable, and accrued liabilities. Our cash equivalents and investments are carried at estimated fair value and remeasured on a recurring basis. The carrying value of accounts payable and accrued liabilities approximate their estimated fair value due to the relatively short-term nature of these instruments. Our valuation techniques used to measure the fair value of money market funds were derived from quoted prices in active markets for identical assets. The valuation techniques used to measure the fair value of investments, all of which have counterparties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. In accordance with fair value accounting requirements, companies may choose to measure eligible financial instruments and certain other items at fair value. We have not elected the fair value option for any eligible financial instruments.
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Issued Accounting Pronouncements Not Yet Adopted In November 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-18, Statement of Cash Flows – Restricted Cash (Topic 230) In October 2016, the FASB, issued ASU, 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers Other Than Inventory In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In March 2016, the FASB, issued ASU 2016-09, Compensation—Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting , which simplifies several aspects of accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities, classification on the statement of cash flows and accounting for forfeitures. The new standard is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years with early adoption permitted. We do not expect the adoption of this new standard to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB, issued ASU, No. 2016-02, Leases (Topic 842)
Reclassifications	Reclassifications Certain amounts in the prior years have been reclassified in order to conform to the current year’s presentation. None of the reclassifications impacted the results of our operations in any of the years presented.

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of Useful Lives of Property and Equipment	The useful lives of property and equipment are as follows: Furniture and office equipment 4 years Computer equipment 3 years Buildings 25 years Fixtures 10 years
Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss per Share	The following common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because their inclusion would have been antidilutive: Year Ended December 31, 2016 2015 2014 Series A convertible preferred stock — — 13,263,967 Stock options 5,429,267 4,814,892 2,566,559 Restricted stock units 17,000 — —

Available-for-Sale Securities20

Available-for-Sale Securities and Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Measured at Fair Value on a Recurring Basis	The following table sets forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Cash and cash equivalents: Cash and money market funds $ 107,977 $ — $ — $ 107,977 Commercial paper — 16,033 — 16,033 Total cash and cash equivalents $ 107,977 $ 16,033 $ — $ 124,010 Investments: Agency securities — 45,571 — 45,571 Corporate securities — 22,031 — 22,031 Commercial paper — 8,669 — 8,669 US government securities — 82,252 — 82,252 Total investments $ — $ 158,523 $ — $ 158,523 December 31, 2015 Level 1 Level 2 Level 3 Total Cash and cash equivalents: Cash and money market funds $ 61,477 $ — $ — $ 61,477 Agency securities — 9,701 — 9,701 Corporate securities — 2,000 — 2,000 Commercial paper — 3,499 — 3,499 Total cash and cash equivalents $ 61,477 $ 15,200 $ — $ 76,677 Investments: Certificates of deposit $ 100 $ — $ — $ 100 Agency securities — 43,325 — 43,325 Corporate securities — 49,596 — 49,596 Commercial paper — 17,843 — 17,843 US government securities — 12,286 — 12,286 Total investments $ 100 $ 123,050 $ — $ 123,150
Summary of Aggregate Market Value, Cost Basis and Gross Unrealized Gains and Losses of Available-for-Sale Investments by Security Type	The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents and investments, as of December 31, 2016 are as follows (in thousands): December 31, 2016 Amortized Cost Gross unrealized gains Gross unrealized losses Total fair value Agency securities $ 45,591 $ 5 $ (25 ) $ 45,571 Corporate securities 22,050 2 (21 ) 22,031 Commercial paper 24,702 — — 24,702 US government securities 82,240 15 (3 ) 82,252 Total available-for-sale investments $ 174,583 $ 22 $ (49 ) $ 174,556 The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents and investments, as of December 31, 2015 are as follows (in thousands): December 31, 2015 Amortized Cost Gross unrealized gains Gross unrealized losses Total fair value Agency securities $ 53,062 $ 2 $ (38 ) $ 53,026 Corporate securities 51,626 28 (58 ) 51,596 Commercial paper 21,342 — — 21,342 US government securities 12,308 — (22 ) 12,286 Total available-for-sale investments $ 138,338 $ 30 $ (118 ) $ 138,250

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Summary of Property And Equipment, Net	Property and equipment, net consists of the following (in thousands): Year Ended December 31, 2016 2015 Furniture and equipment $ 776 $ 220 Computer equipment 850 324 Manufacturing equipment 703 458 Construction in progress 8,749 1,853 Property and equipment, gross 11,078 2,855 Less: accumulated depreciation (687 ) (153 ) Property and equipment, net $ 10,391 $ 2,702
Summary of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): Year Ended December 31, 2016 2015 Compensation and benefits $ 3,195 $ 1,645 Research and development 5,154 972 Professional and consulting 967 381 Other 605 120 Total accrued liabilities $ 9,921 $ 3,118

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Aggregate Minimum Lease Payments	Total future aggregate minimum lease payments under our operating leases are as follows (in thousands): Year Ended December 31, 2017 $ 2,216 2018 1,919 2019 1,905 2020 1,980 2021 1,872 and after 691 Total $ 10,583
Schedule of Future Minimum Lease Payments Due under Capital Lease Obligation	The following is a schedule of future minimum lease payments due under the capital lease obligation as of December 31, 2016 (in thousands): Year Ended December 31, 2017 $ 33 2018 33 2019 34 2020 35 2021 26 Total capital lease obligation 161 Less: amount representing interest 64 Present value of net minimum capital lease payments 97 Less: current portion 12 Total noncurrent capital lease obligation $ 85

Stock-based Awards (Tables)

Stock-based Awards (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	Activity under the 2015 Plan and 2013 Plan is set forth below: Options Outstanding Number Options and Unvested Shares Weighted- Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Balance, December 31, 2015 4,814,892 $ 5.20 9.23 $ 64,211 Options granted 2,343,385 $ 16.02 Options exercised and shares vested (813,102 ) $ 3.49 Options repurchased (68,150 ) $ 0.14 Options cancelled (648,118 ) $ 9.64 Balance, December 31, 2016 5,628,907 $ 9.50 9.02 $ 61,617 Options vested and expected to vest as of December 31, 2016 5,422,307 $ 9.41 8.68 $ 59,856 Options exercisable as of December 31, 2016 3,344,876 $ 2.96 8.66 $ 51,749
Restricted Stock Unit Activity	Restricted stock unit, or RSU, activity under the 2015 Plan is set forth below: Shares Weighted Grant Date Fair Value Unvested Balance, December 31, 2015 — $ — Awarded 17,000 14.01 Released — — Forfeited — — Unvested Balance, December 31, 2016 17,000 $ 14.01
Schedule of Weighted Average Assumptions to Fair Value Stock Options	The following table presents the weighted-average assumptions used to estimate the fair value of options granted: Year Ended December 31, 2016 2015 2014 Expected volatility 74.46 % 74.14 % 79.62 % Risk-free interest rate 1.71 % 1.73 % 1.51 % Expected dividend yield — — — Expected term (in years) 6.03 5.99 4.65 Weighted average grant date fair value $ 10.53 $ 6.11 $ 0.09
Summary of Stock-based Compensation Expense Net of Estimated Forfeitures	Stock-based compensation expense, net of estimated forfeitures, is reflected in the statements of operations and comprehensive loss (in thousands) as summarized below: Year Ended December 31, 2016 2015 2014 Research and development $ 4,838 $ 2,522 $ 23 General and administrative 7,803 3,635 54 Total stock-based compensation expense $ 12,641 $ 6,157 $ 77

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Loss Before Provision for Income Taxes	The following table presents loss before provision for income taxes (in thousands): Year Ended December 31, 2016 2015 2014 Income/(loss) before income taxes Domestic $ (66,210 ) $ (17,489 ) $ (11,120 ) Foreign (14,614 ) (18,327 ) — Total loss before provision for income taxes $ (80,824 ) $ (35,816 ) $ (11,120 )
Summary of Income Tax Expense Differed from Statutory Federal Tax Rate to the Loss Before Taxes	Income tax expense for the years ended December 31, 2016, 2015 and 2014 differed from the amount expected by applying the statutory federal tax rate to the loss before taxes as summarized below (in thousands): Year Ended December 31, 2016 2015 2014 Federal tax benefit at statutory rate 34.00 % 34.00 % 34.00 % State tax benefit, net of federal benefit 0.39 % 3.02 % 6.33 % Stock compensation -1.75 % -1.59 % 0.00 % Change in valuation allowance -27.45 % -20.55 % -41.23 % Research and development credits 2.53 % 2.52 % 1.08 % Foreign income taxed at different rates -6.13 % -17.40 % 0.00 % Other -1.59 % 0.00 % -0.18 % Income tax expense 0.00 % 0.00 % 0.00 %
Significant Components of the Company's Deferred Taxes	The significant components of our deferred taxes are as follows (in thousands): Year Ended December 31, 2016 2015 Deferred tax assets (liabilities): Net operating loss carryforwards $ 27,109 $ 9,857 Start-up costs 1,282 1,612 Stock-based compensation 3,427 1,413 Tax credit carryforwards 3,585 1,296 Accruals 1,041 195 Other 22 (2 ) Total deferred tax assets 36,466 14,371 Less: valuation allowance (36,466 ) (14,371 ) Net deferred income taxes $ — $ —
Summary of Activity Related to Unrecognized Benefits	The following table summarizes the activity related to our unrecognized benefits (in thousands): Year Ended December 31, 2016 2015 Beginning balance - unrecognized tax benefit, gross $ — $ — Increases related to tax positions taken during a prior year — — Decreases related to a tax position taken during a prior year — — Increases related to tax positions taken during the current year 960 — Decreases related to settlements with taxing authorities — — Decreases related to expiration of statute of limitations — — Ending balance - unrecognized tax benefits, gross $ 960 $ —

Selected Quarterly Results of25

Selected Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Unaudited Quarterly Financial Data	The following table presents our unaudited quarterly financial data. Our quarterly results of operations for these periods are not necessarily indicative of our future results of operations. Quarter Ended March 31 June 30 September 30 December 31 2016 (In thousands, except per share data) Operating expenses: Research and development $ 9,976 $ 11,820 $ 15,888 $ 16,958 General and administrative 5,723 6,466 6,353 8,343 Total operating expenses 15,699 18,286 22,241 25,301 Loss from operations (15,699 ) (18,286 ) (22,241 ) (25,301 ) Interest income, net 176 147 155 225 Net loss $ (15,523 ) $ (18,139 ) $ (22,086 ) $ (25,076 ) Net loss per common share, basic and diluted $ (0.37 ) $ (0.43 ) $ (0.53 ) $ (0.55 ) Quarter Ended March 31 June 30 September 30 December 31 2015 (In thousands, except per share data) Operating expenses: Research and development $ 2,069 $ 3,131 $ 3,850 $ 10,766 General and administrative 1,372 4,246 5,174 5,389 Total operating expenses 3,441 7,377 9,024 16,155 Loss from operations (3,441 ) (7,377 ) (9,024 ) (16,155 ) Interest income, net — 1 33 147 Net loss $ (3,441 ) $ (7,376 ) $ (8,991 ) $ (16,008 ) Net loss per common share, basic and diluted $ (0.81 ) $ (1.60 ) $ (0.36 ) $ (0.39 )

Formation and Business of the26

Formation and Business of the Company - Additional Information (Details) $ / shares in Units, $ in Thousands	Nov. 23, 2016USD ($)shares	Aug. 11, 2015USD ($)$ / sharesshares	Jul. 30, 2015shares	Dec. 31, 2016USD ($)$ / sharesshares	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)$ / sharesshares	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)
Organization And Description Of Business [Line Items]
Net loss | $				$ 25,076	$ 22,086	$ 18,139	$ 15,523	$ 16,008	$ 8,991	$ 7,376	$ 3,441	$ 80,824	$ 35,816	$ 11,120
Net cash used in operating activities | $												56,614	35,690	$ 9,777
Accumulated deficit | $				134,157				$ 53,333				134,157	53,333
Cash, cash equivalents and investments | $				$ 282,500								282,500
Proceeds from issuance of common stock | $												$ 145,000	$ 168,119
Proceeds from initial public offering, net of underwriting discount and commissions | $		$ 168,100
Common stock, shares outstanding				50,204,000				42,239,000				50,204,000	42,239,000
Description of stock split												On July 30, 2015, we effected a 1-for-1.317 stock split of our common stock and convertible preferred stock.
Stock split conversion ratio			0.7593
Common stock, shares authorized			55,051,264	290,000,000				290,000,000				290,000,000	290,000,000
Preferred stock, shares authorized			25,051,264	10,000,000				10,000,000				10,000,000	10,000,000
Common stock, par value | $ / shares				$ 0.0001				$ 0.0001				$ 0.0001	$ 0.0001
Preferred stock, par value | $ / shares				$ 0.0001				$ 0.0001				$ 0.0001	$ 0.0001
Private Placement | NHScUS
Organization And Description Of Business [Line Items]
Issuance of common stock upon securities purchase agreement	7,522,084
Proceeds from issuance of common stock | $	$ 145,000
IPO
Organization And Description Of Business [Line Items]
Common stock, shares issued		11,499,999
Common stock issued price per share | $ / shares		$ 16
Shares issued pursuant to exercise of underwriters' option		1,499,999
Outstanding shares of convertible preferred stock converted into common stock		25,051,257
Common stock, shares outstanding				50,204,383								50,204,383
Common stock, shares authorized		290,000,000
Preferred stock, shares authorized		10,000,000
Common stock, par value | $ / shares		$ 0.0001
Preferred stock, par value | $ / shares		$ 0.0001

Summary of Significant Accoun27

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016USD ($)Segmentshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares
Significant Accounting Policies [Line Items]
Number of reportable segments | Segment	1
Number of operating segments | Segment	1
Impairment of any long lived assets | $	$ 0	$ 0	$ 0
Stock options granted | shares	2,343,385	4,192,485	1,635,681
Restricted Stock Units
Significant Accounting Policies [Line Items]
Restricted stock units awarded | shares	17,000	0	0

Summary of Significant Accoun28

Summary of Significant Accounting Policies - Schedule of Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Furniture And Office Equipment
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	4 years
Computer Equipment
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	3 years
Buildings
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	25 years
Fixtures
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	10 years

Summary of Significant Accoun29

Summary of Significant Accounting Policies -Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share			13,263,967
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	5,429,267	4,814,892	2,566,559
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	17,000

Available-for-Sale Securities30

Available-for-Sale Securities and Fair Value Measurements - Summary of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - Fair Value Measurements Recurring - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Cash and cash equivalents
Total cash and cash equivalents	$ 124,010	$ 76,677
Investments:
Total investments	158,523	123,150
Commercial Paper
Cash and cash equivalents
Total cash and cash equivalents	16,033	3,499
Investments:
Total investments	8,669	17,843
US Government Securities
Investments:
Total investments	82,252	12,286
Certificates of Deposit
Investments:
Total investments		100
Corporate Debt Securities
Cash and cash equivalents
Total cash and cash equivalents		2,000
Investments:
Total investments	22,031	49,596
Agency Securities
Cash and cash equivalents
Total cash and cash equivalents		9,701
Investments:
Total investments	45,571	43,325
Cash and money market funds
Cash and cash equivalents
Total cash and cash equivalents	107,977	61,477
Level 1
Cash and cash equivalents
Total cash and cash equivalents	107,977	61,477
Investments:
Total investments		100
Level 1 | Certificates of Deposit
Investments:
Total investments		100
Level 1 | Cash and money market funds
Cash and cash equivalents
Total cash and cash equivalents	107,977	61,477
Level 2
Cash and cash equivalents
Total cash and cash equivalents	16,033	15,200
Investments:
Total investments	158,523	123,050
Level 2 | Commercial Paper
Cash and cash equivalents
Total cash and cash equivalents	16,033	3,499
Investments:
Total investments	8,669	17,843
Level 2 | US Government Securities
Investments:
Total investments	82,252	12,286
Level 2 | Corporate Debt Securities
Cash and cash equivalents
Total cash and cash equivalents		2,000
Investments:
Total investments	22,031	49,596
Level 2 | Agency Securities
Cash and cash equivalents
Total cash and cash equivalents		9,701
Investments:
Total investments	$ 45,571	$ 43,325

Available-for-Sale Securities31

Available-for-Sale Securities and Fair Value Measurements - Summary of Aggregate Market Value, Cost Basis, and Gross Unrealized Gains and Losses of Available for Sale Investments by Security Type (Details) - Available-for-sale Securities - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	$ 174,583	$ 138,338
Gross Unrealized Gains	22	30
Gross Unrealized Losses	(49)	(118)
Total Available-for-Sale Investments	174,556	138,250
Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	24,702	21,342
Total Available-for-Sale Investments	24,702	21,342
US Government Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	82,240	12,308
Gross Unrealized Gains	15
Gross Unrealized Losses	(3)	(22)
Total Available-for-Sale Investments	82,252	12,286
Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	22,050	51,626
Gross Unrealized Gains	2	28
Gross Unrealized Losses	(21)	(58)
Total Available-for-Sale Investments	22,031	51,596
Agency Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	45,591	53,062
Gross Unrealized Gains	5	2
Gross Unrealized Losses	(25)	(38)
Total Available-for-Sale Investments	$ 45,571	$ 53,026

Available-for-Sale Securities32

Available-for-Sale Securities and Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Available-for-sale securities, gross realized gain (loss)	$ 0	$ 0	$ 0

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 11,078	$ 2,855
Less: accumulated depreciation	(687)	(153)
Property and equipment, net	10,391	2,702
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	776	220
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	850	324
Manufacturing equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	703	458
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8,749	$ 1,853

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
Balance Sheet Related Disclosures [Abstract]
Depreciation Expense	$ 534	$ 115	$ 29

Balance Sheet Components - Su35

Balance Sheet Components - Summary of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities Current [Abstract]
Compensation and benefits	$ 3,195	$ 1,645
Research and development	5,154	972
Professional and consulting	967	381
Other	605	120
Total accrued liabilities	$ 9,921	$ 3,118

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2015ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Aug. 31, 2015ft²	Mar. 31, 2015ft²
Commitments And Contingencies [Line Items]
Term of capital lease agreement		5 years
Long-term purchase commitment amount		$ 1.2
Long-term purchase commitment period		5 years
Facility Leases
Commitments And Contingencies [Line Items]
Rent expense under operating leases		$ 1.7	$ 0.6	$ 0.1
Facility Leases | Corporate Headquarters
Commitments And Contingencies [Line Items]
Leased area | ft²					26,355	11,665
Term of lease			72 months
Security deposit		0.3
Facility Leases | Manufacturing Facility
Commitments And Contingencies [Line Items]
Leased area | ft²	20,000
Term of lease	120 months
Design costs related to building		0.3
Construction in progress for costs incurred by the lessor		$ 0.7

Commitments and Contingencies37

Commitments and Contingencies - Future Aggregate Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,017	$ 2,216
2,018	1,919
2,019	1,905
2,020	1,980
2,021	1,872
and after	691
Total	$ 10,583

Commitments and Contingencies38

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Due under Capital Lease Obligation (Details) $ in Thousands	Dec. 31, 2016USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,017	$ 33
2,018	33
2,019	34
2,020	35
2,021	26
Total capital lease obligation	161
Less: amount representing interest	64
Present value of net minimum capital lease payments	97
Less: current portion	12
Total noncurrent capital lease obligation	$ 85

Stockholders Equity - Additiona

Stockholders Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 23, 2016	Jan. 31, 2015	Feb. 28, 2015	Dec. 31, 2016	Dec. 31, 2015	Aug. 11, 2015	Jul. 30, 2015
Stockholders Equity [Line Items]
Preferred stock, shares issued				0	0
Preferred stock, par value				$ 0.0001	$ 0.0001
Preferred stock, shares authorized				10,000,000	10,000,000		25,051,264
Preferred stock, shares outstanding				0	0
Common stock, par value				$ 0.0001	$ 0.0001
Proceeds from issuance of common stock				$ 145,000	$ 168,119
NHScUS | Purchase Agreement
Stockholders Equity [Line Items]
Issuance of common stock upon securities purchase agreement	7,522,084
Common stock, par value	$ 0.0001
Proceeds from issuance of common stock	$ 145,000
Initial Public Offering
Stockholders Equity [Line Items]
Preferred stock, par value						$ 0.0001
Outstanding shares of convertible preferred stock converted into common stock						25,051,257
Preferred stock, shares authorized						10,000,000
Common stock, par value						$ 0.0001
Series A Convertible Preferred Stock
Stockholders Equity [Line Items]
Stock repurchased from investors		2,260,706
Preferred stock, redemption price per share		$ 5.69
Repurchase of convertible preferred stock		$ 12,900			$ 12,874
Series B Convertible Preferred Stock
Stockholders Equity [Line Items]
Preferred stock, shares issued			14,047,996
Preferred stock, par value			$ 0.0001
Share price (per share)			$ 5.69		$ 5.69
Gross cash proceeds from preferred stock			$ 80,000
Offering costs for issuance and sale of convertible preferred stock					$ 221
Convertible Preferred Stock
Stockholders Equity [Line Items]
Preferred stock, shares issued				0	0
Preferred stock, shares authorized				10,000,000	10,000,000
Preferred stock, shares outstanding				0	0

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details)	1 Months Ended	12 Months Ended
	Jul. 31, 2015shares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)Grant$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Jan. 31, 2013shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares outstanding | shares		5,628,907	4,814,892
Intrinsic Value of option exercised | $		$ 6,500,000
Stock option granted, per share weighted average grant-date fair value | $ / shares		$ 10.53	$ 6.11	$ 0.09
Number of shares available for grant | shares		2,343,385	4,192,485	1,635,681
Expected dividend yield		0.00%
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized employee stock-based compensation | $		$ 100,000
Expected recognized over weighted-average remaining vesting period		2 months 12 days
Former Executive
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Accelerated stock compensation expense | $		$ 900,000	$ 1,400,000	$ 0
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option granted, per share weighted average grant-date fair value | $ / shares		$ 10.53	$ 6.11	$ 0.09
Tax benefit realized from option | $		$ 0
Stock option grant modification expense | $		90,000
Unrecognized employee stock-based compensation | $		$ 27,300,000	$ 17,200,000
Expected recognized over weighted-average remaining vesting period		2 years 8 months 19 days	3 years 2 months 23 days
Stock Options | Non-Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant | shares			213,354
Number of grants issued | Grant			1
Maximum | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period		4 years
Minimum | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period		2 years
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance | shares	4,681,544
Number of shares available for future grant | shares		4,344,487	4,443,479
Minimum percentage of voting rights of all classes of stock	10.00%
Percentage of statutory stock options	110.00%
Options expiration period	10 years
2015 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiration period	10 years
2015 Plan | First Anniversary
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	4 years
Option vesting rights, percentage	25.00%
2015 Plan | Thereafter
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option vesting rights, percentage	2.08%
2015 Plan | Over Two Years
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	2 years
Option vesting rights, percentage	4.17%
2015 Plan | Over Four Years
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	4 years
Option vesting rights, percentage	2.08%
2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance | shares		0			0
Number of shares available for future grant | shares		0
Unvested shares issued | shares		199,538	599,242
Unvested shares outstanding | shares		199,538	599,242
Exercise liability | $		$ 60,000	$ 220,000
Exercise liability current | $		50,000	140,000
Exercise liability non current | $		$ 10,000	$ 80,000

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Options and Unvested Shares
Number of Options and Unvested Shares, Beginning Balance	4,814,892
Number of Options and Unvested Shares, Options granted	2,343,385	4,192,485	1,635,681
Number of Options and Unvested Shares, Options exercised and shares vested	(813,102)
Number of Options and Unvested Shares, Options repurchased	(68,150)
Number of Options and Unvested Shares, Options cancelled	(648,118)
Number of Options and Unvested Shares, Ending Balance	5,628,907	4,814,892
Number of Options and Unvested Shares, Options vested and expected to vest as of December 31,2016	5,422,307
Number of Options and Unvested Shares, Options exercisable as of December 31, 2016	3,344,876
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Beginning Balance	$ 5.20
Weighted-Average Exercise Price, Options granted	16.02
Weighted-Average Exercise Price, Options exercised and shares vested	3.49
Weighted-Average Exercise Price, Options repurchased	0.14
Weighted-Average Exercise Price, Options cancelled	9.64
Weighted-Average Exercise Price, Ending Balance	9.50	$ 5.20
Weighted-Average Exercise Price, Options vested and expected to vest as of December 31, 2016	9.41
Weighted-Average Exercise Price, Options exercisable as of December 31, 2016	$ 2.96
Weighted Average Remaining Contractual Life (in years)
Weighted Average Remaining Contractual Life (in years), Balance	9 years 7 days	9 years 2 months 23 days
Weighted Average Remaining Contractual Life, Options vested and expected to vest as of December 31,2016	8 years 8 months 5 days
Weighted Average Remaining Contractual Life, Options exercisable as of December 31, 2016	8 years 7 months 28 days
Aggregate Intrinsic Value, Balance	$ 61,617	$ 64,211
Aggregate Intrinsic Value, Options vested and expected to vest as of December 31, 2016	59,856
Aggregate Intrinsic Value, Options exercisable as of December 31, 2016	$ 51,749

Stock-Based Awards - Restricted

Stock-Based Awards - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Awarded	17,000	0	0
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Awarded	17,000
Unvested Shares, Ending Balance	17,000
Weighted Average Grant Date Fair Value, Awarded	$ 14.01
Weighted Average Grant Date Fair Value, Ending Balance	$ 14.01

Stock-Based Awards - Schedule o

Stock-Based Awards - Schedule of Weighted Average Assumptions to Fair Value of Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Expected volatility	74.46%	74.14%	79.62%
Risk-free interest rate	1.71%	1.73%	1.51%
Expected dividend yield	0.00%
Expected term (in years)	6 years 11 days	5 years 11 months 27 days	4 years 7 months 24 days
Weighted average grant date fair value	$ 10.53	$ 6.11	$ 0.09

Stock-Based Awards - Summary 44

Stock-Based Awards - Summary of Stock-based Compensation Expense Net of Estimated Forfeitures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 12,641	$ 6,157	$ 77
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,838	2,522	23
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,803	$ 3,635	$ 54

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Tax provision	$ 0	$ 0	$ 0
Net change in valuation allowance	22,100,000	7,400,000
Interest and penalties related to unrecognized tax benefits	0	0
Federal
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 81,000,000	24,700,000
Net operating loss carryforward expiration year	2,031
Research credit carryforwards	$ 3,900,000	3,900,000
Research credit carryforward expiration year	2,032
Federal | Windfall Stock Option Deductions | ASU 2016-09
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 3,600,000
Other State
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 2,400,000	400,000
Net operating loss carryforward expiration year	2,030
Other State | Windfall Stock Option Deductions | ASU 2016-09
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 100,000
California
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 12,000,000	12,000,000
Net operating loss carryforward expiration year	2,031
Research credit carryforwards	$ 900,000	$ 900,000
California | Windfall Stock Option Deductions | ASU 2016-09
Operating Loss Carryforwards [Line Items]
Operating loss, Net	$ 0

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income/(loss) before income taxes
Domestic	$ (66,210)	$ (17,489)	$ (11,120)
Foreign	(14,614)	(18,327)
Loss before provision for income taxes	$ (80,824)	$ (35,816)	$ (11,120)

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Expense Differed from Statutory Federal Tax Rate to the Loss Before Taxes (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal tax benefit at statutory rate	34.00%	34.00%	34.00%
State tax benefit, net of federal benefit	0.39%	3.02%	6.33%
Stock compensation	(1.75%)	(1.59%)	0.00%
Change in valuation allowance	(27.45%)	(20.55%)	(41.23%)
Research and development credits	2.53%	2.52%	1.08%
Foreign income taxed at different rates	(6.13%)	(17.40%)	0.00%
Other	(1.59%)	0.00%	(0.18%)
Income tax expense	0.00%	0.00%	0.00%

Income Taxes - Significant Comp

Income Taxes - Significant Components of the Company's Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets (liabilities):
Net operating loss carryforwards	$ 27,109	$ 9,857
Start-up costs	1,282	1,612
Stock-based compensation	3,427	1,413
Tax credit carryforwards	3,585	1,296
Accruals	1,041	195
Other	22	(2)
Total deferred tax assets	36,466	14,371
Less: valuation allowance	$ (36,466)	$ (14,371)

Income Taxes - Summary of Activ

Income Taxes - Summary of Activity Related to Unrecognized Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Income Tax Disclosure [Abstract]
Increases related to tax positions taken during the current year	$ 960
Ending balance - unrecognized tax benefits, gross	$ 960

Selected Quarterly Results of50

Selected Quarterly Results of Operations (Unaudited) - Schedule of 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, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating expenses
Research and development	$ 16,958	$ 15,888	$ 11,820	$ 9,976	$ 10,766	$ 3,850	$ 3,131	$ 2,069	$ 54,642	$ 19,816	$ 8,181
General and administrative	8,343	6,353	6,466	5,723	5,389	5,174	4,246	1,372	26,885	16,181	2,951
Total operating expenses	25,301	22,241	18,286	15,699	16,155	9,024	7,377	3,441	81,527	35,997	11,132
Loss from operations	(25,301)	(22,241)	(18,286)	(15,699)	(16,155)	(9,024)	(7,377)	(3,441)	(81,527)	(35,997)	(11,132)
Interest income, net	225	155	147	176	147	33	1		703	181	12
Net loss	$ (25,076)	$ (22,086)	$ (18,139)	$ (15,523)	$ (16,008)	$ (8,991)	$ (7,376)	$ (3,441)	$ (80,824)	$ (35,816)	$ (11,120)
Net loss per common share, basic and diluted	$ (0.55)	$ (0.53)	$ (0.43)	$ (0.37)	$ (0.39)	$ (0.36)	$ (1.60)	$ (0.81)	$ (1.89)	$ (1.88)	$ (3.80)