Cidara Therapeutics (CDTX) 10-K 18 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	CDTX
Entity Registrant Name	Cidara Therapeutics, Inc.
Entity Central Index Key	1,610,618
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	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		13,822,747
Entity Public Float			$ 95.2

Condensed Balance Sheets

Condensed Balance Sheets - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 62,562,000	$ 22,796,000
Short-term investments	44,952,000	0
Prepaid expenses and other current assets	704,000	217,000
Total current assets	108,218,000	23,013,000
Property and equipment, net	1,684,000	863,000
Other assets	72,000	474,000
Total assets	109,974,000	24,350,000
Current liabilities:
Accounts payable	3,095,000	1,177,000
Accrued liabilities	1,415,000	1,622,000
Accrued compensation and benefits	1,464,000	414,000
Total current liabilities	5,974,000	3,213,000
Other long-term liabilities	88,000	34,000
Total liabilities	$ 6,062,000	$ 3,247,000
Commitments and contingencies
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding at December 31, 2015; no shares authorized, issued, or outstanding at December 31, 2014.
Common stock, $0.0001 par value; 200,000,000 and 185,000,000 shares authorized at December 31, 2015 and 2014, respectively; 13,942,520 and 13,786,285 shares issued and outstanding, respectively, at December 31, 2015; 1,494,506 and 1,132,738 shares issued and outstanding, respectively, at December 31, 2014	$ 1,000
Additional paid-in capital	149,416,000	$ 1,859,000
Accumulated other comprehensive loss	(8,000)
Accumulated deficit	(45,497,000)	(13,304,000)
Total stockholders' equity (deficit)	103,912,000	(11,445,000)
Total liabilities, convertible preferred stock, and stockholders' equity (deficit)	$ 109,974,000	24,350,000
Series A Convertible Preferred Stock
Convertible preferred stock
Convertible preferred stock		32,548,000
Stockholders' equity (deficit):
Total stockholders' equity (deficit)		$ 32,548,000

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	185,000,000
Common stock, shares issued	13,942,520	1,494,506
Common stock, shares outstanding	13,786,285	1,132,738
Series A Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	0	127,214,000
Convertible preferred stock, shares issued	0	97,526,081
Convertible preferred stock, shares outstanding	0	97,526,081

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating expenses:
Research and development	$ 23,475	$ 6,710	$ 810
Cost of in-process research and development acquired		1,607
General and administrative	8,838	3,306	272
Total operating expenses	32,313	11,623	1,082
Loss from operations	(32,313)	(11,623)	(1,082)
Other income (expense):
Interest income (expense), net	120	(88)	(95)
Change in fair value of convertible notes payable		(183)	(167)
Total other income (expense)	120	(271)	(262)
Net loss	(32,193)	(11,894)	(1,344)
Other comprehensive loss:
Unrealized loss on short-term investments	(8)
Comprehensive loss	$ (32,201)	$ (11,894)	$ (1,344)
Basic and diluted net loss per share	$ (3.25)	$ (14.51)	$ (4.15)
Shares used to compute basic and diluted net loss per share	9,920,382	819,868	323,689

Statements of Convertible Prefe

Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Other Comprehensive Income/(Loss)	IPO	IPOSeries A Convertible Preferred Stock	IPOSeries B Convertible Preferred Stock	IPOCommon Stock	IPOAdditional Paid-in Capital
Balance, beginning at Dec. 31, 2012	$ (65)				$ 1	$ (66)
Balance, beginning (in shares) at Dec. 31, 2012				385,825
Modification of founders shares to add vesting restrictions, shares				(118,110)
Vesting of restricted, shares				98,837
Stock-based compensation	11				11
Net loss	(1,344)					(1,344)
Balance, ending at Dec. 31, 2013	(1,398)				12	(1,410)
Balance, ending (in shares) at Dec. 31, 2013				366,552
Issuance of stock, value		$ 29,866
Issuance of stock, shares		89,360,118
Issuance of Series A convertible preferred stock upon conversion of convertible notes payable, value		$ 2,682
Issuance of Series A convertible preferred stock upon conversion of convertible notes payable, shares		8,165,963
Issuance of common stock for in-process research and development, value	1,607				1,607
Issuance of common stock for in-process research and development, shares				703,092
Vesting of restricted, value	5				5
Vesting of restricted, shares				61,913
Issuance of common stock for exercise of stock options, value	3				3
Issuance of common stock for exercise of stock options, shares				1,181
Stock-based compensation	232				232
Net loss	(11,894)					(11,894)
Balance, ending at Dec. 31, 2014	(11,445)	$ 32,548			1,859	(13,304)
Balance, ending (in shares) at Dec. 31, 2014		97,526,081		1,132,738
Issuance of stock, value	69,271		$ 41,921		69,271
Issuance of stock, shares			94,533,183	4,800,000
Conversion of Series A and Series B convertible preferred upon initial public offering, value								$ 74,469	$ (32,548)	$ (41,921)	$ 1	$ 74,468
Conversion of Series A and Series B convertible preferred upon initial public offering, shares									(97,526,081)	(94,533,183)	7,561,380
Issuance of common stock under employee stock purchase plan, value	225				225
Issuance of common stock under employee stock purchase plan, shares				19,164
Vesting of restricted, value	499				499
Vesting of restricted, shares				249,465
Issuance of common stock for exercise of stock options, value	61				61
Issuance of common stock for exercise of stock options, shares				23,538
Stock-based compensation	3,033				3,033
Unrealized loss on marketable securities	(8)						$ (8)
Net loss	(32,193)					(32,193)
Balance, ending at Dec. 31, 2015	$ 103,912			$ 1	$ 149,416	$ (45,497)	$ (8)
Balance, ending (in shares) at Dec. 31, 2015				13,696,286

Statements of Convertible Pref6

Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Series A Convertible Preferred Stock
Issuance cost		$ 159
Series B Convertible Preferred Stock
Issuance cost	$ 99

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net loss	$ (32,193)	$ (11,894)	$ (1,344)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	461	179
Stock-based compensation	3,033	232	11
Non-cash interest expense		66	66
Amortization of discount or premium on short-term investments	(42)
Change in fair value of convertible notes payable		183	167
Amortization of debt issue costs	22	23	29
Deferred rent	54	34
Purchase of in-process research and development		1,607
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(487)	(204)	(13)
Accounts payable and accrued liabilities	2,143	1,746	36
Accrued compensation	1,050	414
Other assets		(96)
Net cash used in operating activities	(25,959)	(7,710)	(1,048)
Investing activities:
Purchases of short-term investments	(54,918)
Maturities of short-term investments	10,000
Purchases of property and equipment	(1,170)	(991)
Net cash used in investing activities	(46,088)	(991)
Financing activities:
Proceeds from initial public offering, net of offering costs	69,505
Deferred initial public offering costs		(233)
Proceeds from exercise of stock options and employee stock purchase plan	387	749
Proceeds from issuance of convertible notes payable, net of offering costs		930	1,232
Net cash provided by financing activities	111,813	31,312	1,232
Net increase in cash and cash equivalents	39,766	22,611	184
Cash and cash equivalents at beginning of period	22,796	185	1
Cash and cash equivalents at end of period	62,562	22,796	$ 185
Non-cash investing activity:
Property and equipment acquired but not yet paid	113	51
Non-cash financing activities:
Deferred initial public offering costs	234	146
Vesting of early exercised stock options	499
Series A Convertible Preferred Stock
Financing activities:
Proceeds from issuance convertible preferred stock, net of offering costs		29,866
Non-cash financing activities:
Conversion convertible preferred stock to common upon initial public offering	32,548
Conversion of convertible notes payable and accrued interest to Series A convertible preferred shares		$ 2,682
Series B Convertible Preferred Stock
Financing activities:
Proceeds from issuance convertible preferred stock, net of offering costs	41,921
Non-cash financing activities:
Conversion convertible preferred stock to common upon initial public offering	$ 41,921

The Company and Basis of Presen

The Company and Basis of Presentation	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company and Basis of Presentation	1. THE COMPANY AND BASIS OF PRESENTATION Description of Business Cidara Therapeutics, Inc., or the Company, was originally incorporated in Delaware in December 2012 as K2 Therapeutics, Inc., and its name was changed to Cidara Therapeutics, Inc. in July 2014. The Company is a biotechnology company focused on the discovery, development and commercialization of novel anti-infectives. The Company’s initial product portfolio is comprised of proprietary product candidates for the treatment of serious fungal infections. On April 2, 2015, the Company’s board of directors and stockholders approved a 1-for-25.4 reverse stock split of its outstanding common stock. The accompanying financial statements and notes to the financial statements give retroactive effect to the reverse stock split for all periods presented. On April 20, 2015, the Company completed its initial public offering (“IPO”), whereby the Company sold 4,800,000 shares of common stock at a price of $16.00 per share. Proceeds from the IPO were approximately $69.3 million, net of underwriting discounts and commissions and offering costs. In connection with the IPO, the outstanding shares of the Company’s Series A convertible preferred stock (“Series A preferred”) and Series B convertible preferred stock (“Series B preferred”) automatically converted into 7,561,380 shares of common stock. Basis of Presentation The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The accompanying financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has experienced net losses and negative cash flows from operating activities since its inception. At December 31, 2015, the Company had an accumulated deficit of $45.5 million. The Company expects to continue to incur net losses into the foreseeable future. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company plans to continue to fund its losses from operations and capital funding needs through debt and equity financing or through collaborations or partnerships with other companies. Debt or equity financing or collaborations and partnerships with other companies may not be available on a timely basis on terms acceptable to the Company, or at all. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Use of Estimates —The preparation of financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s financial statements relate to estimating the fair value of the Company’s common shares used to account for share-based compensation and certain accruals, including those related to preclinical and clinical activities. Although the estimates are based on the Company’s knowledge of current events, comparable companies, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Segment Information —Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Cash and Cash Equivalents —The Company considers all short-term investments purchased with a maturity of three months or less when acquired to be cash equivalents. Investments Available-for-Sale — Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Securities with maturity dates of 12 months or less from the date of purchase are classified as short-term investments and securities with maturity dates of more than 12 months are classified as long-term investments. Property and Equipment — We carry our property and equipment at cost, which consists of lab equipment, computer equipment and software, office equipment, furniture and fixtures and leasehold improvements. Property and equipment is depreciated using the straight-line method over the estimated useful lives (generally three to seven years). Leasehold improvements are amortized over the lesser of their useful life or the remaining lease term, including any renewal periods that are deemed to be reasonably assured. Repair and maintenance costs are expensed as incurred. Concentration of Credit Risk —The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. Periodically, the Company maintains deposits in government insured financial institutions in excess of government insured limits. The Company invests its cash balances in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to significant credit risk. Patent Costs — The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications) and such costs are included in general and administrative expenses in the accompanying statements of operations. Convertible Preferred Stock —The Company’s Series A preferred and Series B preferred were classified as temporary equity instead of stockholders’ equity (deficit) in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities as the stock was conditionally redeemable at the holder’s option upon certain change in control events that were outside the Company’s control, including the liquidation, sale, or transfer of control of the Company. All of the outstanding Series A Preferred and Series B Preferred was converted to common upon the IPO in April 2015. Income Taxes —The Company follows the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes , or ASC 740, in reporting deferred income taxes. The ASC 740 requires a company to recognize deferred tax assets and liabilities for expected future income tax consequences of events that have been recognized in the Company’s financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740, which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes. Research and Development Costs —Research and development expenses consist of wages, benefits and stock-based compensation charges for research and development employees, scientific consultant fees, facilities and overhead expenses, laboratory supplies, manufacturing expenses, and preclinical and clinical trial costs. The Company accrues clinical trial expenses based on work performed which relies on estimates of total costs incurred based on patient enrollment, completion of studies, and other events. Costs incurred in purchasing technology assets and intellectual property are charged to research and development expense if the technology has not been conclusively proven to be feasible and has no alternative future use. Comprehensive Loss —Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. The Company’s only component of other comprehensive loss is unrealized gains (losses) on short-term marketable securities. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss and as a separate component of the statements of convertible preferred stock and stockholders’ equity (deficit) for all periods presented. Stock-based Compensation — The Company accounts for stock-based compensation expense related to employee stock options, restricted stock grants, and employee stock purchase plan rights by estimating the fair value on the date of grant using the Black-Scholes option pricing model. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized ratably over the requisite service period of the awards, net of estimated forfeitures. The Company accounts for stock options granted to non-employees using the fair value approach. These option grants are subject to periodic revaluation over their vesting terms. Net Loss Per Share —Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, convertible notes payable, unvested restricted common stock subject to repurchase, and options outstanding under the Company’s stock option plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding. The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares): December 31, 2015 2014 Convertible preferred stock - 3,839,604 Common stock options issued and outstanding 1,437,583 709,136 Common stock subject to repurchase 156,235 361,768 Total 1,593,818 4,910,508 Fair Value of Financial Instruments — The Company follows authoritative guidance with respect to fair value reporting issued by the FASB for financial assets and liabilities, which defines fair value, provides guidance for measuring fair value and requires certain disclosures. The guidance does not apply to measurements related to share-based payments. The guidance discusses valuation techniques such as the market approach (comparable market prices), the income approach (present value of future income or cash flow), and the cost approach (cost to replace the service capacity of an asset or replacement cost). The guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The Company’s financial instruments consist of cash and cash equivalents, marketable securities, prepaid expenses, accounts payable, and accrued liabilities. Fair value estimates of these instruments are made at a specific point in time based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amount of cash and cash equivalents, prepaid expenses, accounts payable, and accrued liabilities are generally considered to be representative of their respective fair values because of the short-term nature of those instruments. The fair value of marketable securities is based upon market prices quoted on the last day of the fiscal period or other observable market inputs. Recently Issued Accounting Standards — During 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-15, “Presentation of Financial Statements—Going Concern.” The update requires management to assess an entity’s ability to continue as a going concern and to provide related footnote disclosure in certain circumstances. The update is effective for annual reporting periods ending after December 15, 2016 and interim periods thereafter. Early application is permitted. The Company is currently assessing the impact that this standard will have on its financial statements. During 2015, the FASB issued ASU 2015-17, “Income Taxes: Balance Sheet Classification of Deferred Taxes,” which amends existing guidance to require companies to classify deferred tax assets and liabilities as noncurrent in the statement of financial position. The update is effective for annual periods beginning after December 15, 2016, and early adoption is permitted. The update may be adopted on either a prospective or retrospective basis. The Company adopted ASU 2015-17 in the fourth quarter of 2015 on a retrospective basis. The adoption of this guidance did not have a material impact on the Company’s financial statements. During 2016, the FASB issued ASU 2016-02, “Leases,” which requires that lease arrangements longer than 12 months result in an entity recognizing an asset and liability. The updated guidance is effective for interim and annual periods beginning after December 15, 2018, and early adoption is permitted. The Company is currently assessing the impact that this standard will have on its financial statements.

Short-Term Investments

Short-Term Investments	12 Months Ended
	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Short-Term Investments	3. SHORT-TERM INVESTMENTS The following table summarizes the available-for-sale securities held at December 31, 2015 (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value Certificates of deposit $ 20,000 $ - $ - $ 20,000 Commercial paper 24,960 - (8 ) $ 24,952 Total $ 44,960 $ - $ (8 ) $ 44,952 All available-for-sale securities held at December 31, 2015 will mature in less than one year. At December 31, 2014, the Company had no available-for-sale securities.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. FAIR VALUE MEASUREMENTS The Company follows ASC 820-10, Fair Value Measurements and Disclosures As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions, which reflect those that a market participant would use. At December 31, 2015, the Company held certificates of deposit, which are valued at cost, and commercial paper, which is valued using observable market inputs including reported trades, broker/dealer quotes, bids and/or offers. At December 31, 2015 and 2014, the Company held securities of a money market fund which invested in short-term U.S. Treasury securities, the prices of which were available from quoted prices in active markets. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis: TOTAL LEVEL 1 LEVEL 2 LEVEL 3 December 31, 2015 Assets: Cash equivalents and money market funds $ 12,353 $ 12,353 $ - $ - Certificates of deposit included in cash and cash equivalents 50,000 - 50,000 - Certificates of deposit included in short-term investments 20,000 - 20,000 - Commercial paper 24,952 - 24,952 - Total assets at fair value $ 107,305 $ 12,353 $ 94,952 $ - December 31, 2014 Assets: Cash equivalents and money market funds $ 20,769 $ 20,769 $ - $ - Total assets at fair value $ 20,769 $ 20,769 $ - $ -

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Property and Equipment	5. PROPERTY AND EQUIPMENT Property and equipment consisted of the following (in thousands): December 31, 2015 2014 Laboratory equipment $ 1,438 $ 687 Leasehold improvements 425 94 Computer hardware and software 242 210 Office equipment 111 42 Furniture and fixtures 105 9 2,321 1,042 Less accumulated depreciation and amortization (637 ) (179 ) Total $ 1,684 $ 863 Depreciation and amortization of property and equipment of $461,000 and $179,000 was recorded for the years ended December 31, 2015 and 2014, respectively.

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	6. DEBT 2013 Convertible Notes Payable During 2013, the Company issued convertible notes (the 2013 Notes) to a major shareholder of the Company, 5AM Ventures, for an aggregate of $1,250,000. The 2013 Notes bore interest at 8%, which compounded annually. The 2013 Notes were convertible into preferred shares of the Company’s equity securities at a 15% discount to the sales price of the equity securities sold at the next financing or a series of related transactions yielding gross proceeds to the Company of at least $13,750,000 (defined as a Qualified Financing). The 2013 Notes were to mature on the earlier of a Qualified Financing, a change in control, or February 8, 2014, or such later date as provided for by the written consent of the note holders. In January 2014, the holders of the 2013 Notes executed a written consent to extend the maturity date of the 2013 Notes to July 30, 2014. 2014 Convertible Notes Payable In January and February 2014, the Company issued convertible notes (the 2014 Notes) to 5AM Ventures and certain non-affiliated investors for $500,000 and $450,000, respectively. The 2014 Notes bore interest at 8%, which compounded annually. The 2014 Notes were convertible into preferred shares of the Company’s equity securities at a 15% discount to the sales price of the equity securities sold in a Qualified Financing. The 2014 Notes were to mature on the earlier of a Qualified Financing, a change in control, or July 30, 2014, or such later date as provided for by the written consent of the note holders On May 30, 2014, the outstanding principal balance of both the 2013 Notes and the 2014 Notes plus all accrued interest thereon converted into 321,492 shares of Series A Preferred, which were converted to common stock upon the Company’s IPO in April, 2015.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	7. STOCKHOLDERS’ EQUITY Preferred Stock —The Company has 10,000,000 shares of preferred stock authorized at December 31, 2015. The Company had no shares of preferred stock issued or outstanding at December 31, 2015. Under the amended and restated certificate of incorporation, the Company’s board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding. Common Stock —The Company had 200,000,000 shares of common stock authorized as of December 31, 2015. Holders of outstanding shares of common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the holders of common stock. Subject to the rights of the holders of any class of the Company’s capital stock having any preference or priority over common stock, the holders of common stock are entitled to receive dividends that are declared by the Company’s board of directors out of legally available funds. In the event of a liquidation, dissolution or winding-up, the holders of common stock are entitled to share ratably in the net assets remaining after payment of liabilities, subject to prior rights of preferred stock, if any, then outstanding. The common stock has no preemptive rights, conversion rights, redemption rights or sinking fund provisions, and there are no dividends in arrears or default. All shares of common stock have equal distribution, liquidation and voting rights, and have no preferences or exchange rights.

Equity Incentive Plans

Equity Incentive Plans	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	8. EQUITY INCENTIVE PLANS 2015 Equity Incentive Plan In March 2015, the Company’s board of directors and stockholders approved and adopted the 2015 Equity Incentive Plan (“2015 EIP”). Under the 2015 EIP, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units, and other awards to individuals who are employees, officers, directors, or consultants of the Company. A total of 1,829,020 shares of common stock were reserved for issuance under the 2015 EIP. The number of shares of stock available for issuance under the 2015 EIP will be automatically increased each January 1, beginning on January 1, 2016, by 4% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 or such lesser number as determined by the Company’s board of directors. Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2015 EIP. Stock options granted by the Company generally vest over a three- or four-year year period. Certain stock options are subject to acceleration of vesting in the event of certain change of control transactions. The stock options may be granted for a term of up to ten years from the date of grant. The exercise price for stock options granted under the 2015 EIP must be at a price no less than 100% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided that for an incentive stock option granted to an employee who at the time of grant owns stock representing more than 10% of the voting power of all classes of stock of the Company, the exercise price shall be no less than 110% of the estimated value on the date of grant. As of December 31, 2015, the Company had 1,788,396 shares available for future issuance to employees, nonemployee directors, and consultants of the Company under the 2015 EIP. 2015 Employee Stock Purchase Plan In March 2015, the Company’s board of directors and stockholders approved and adopted the 2015 Employee Stock Purchase Plan (“ESPP”). A total of 245,168 shares of common stock were initially reserved for issuance under the ESPP. In addition, the number of shares of stock available for issuance under the ESPP will be automatically increased each January 1, beginning on January 1, 2016, by the lesser of (i) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, or (ii) 490,336 shares. The ESPP allows substantially all employees to purchase the Company’s common stock through a payroll deduction at a price equal to 85% of the lower of the fair market value of the stock as of the beginning or the end of each purchase period. An employee’s payroll deductions under the under the ESPP are limited to 15% of the employee’s eligible compensation. During the year ended December 31, 2015, 19,164 shares were issued pursuant to the ESPP. Restricted Stock The Company permits early exercise of certain stock options. Any unvested shares are restricted and subject to repurchase by the Company until the conditions for vesting are met. At December 31, 2015 and 2014, the liabilities for the cash received from the early exercise of stock options were $341,000 and $736,000, respectively, and were classified in accrued liabilities on the balance sheet. The Company reduces the liability as the underlying shares vest in accordance with the vesting terms outlined in the stock option agreements which, generally, is 4 years. At December 31, 2015, 156,235 unvested shares were subject to repurchase by the Company. Stock Options The following table summarizes stock option activity during the year ended December 31, 2015: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value Outstanding at December 31, 2014 709,136 $ 2.29 9.73 $ 2,522 Options granted 899,728 8.56 Options exercised (67,468 ) 2.40 Options canceled (103,813 ) 2.58 Outstanding at December 31, 2015 1,437,583 $ 6.19 8.94 $ 15,774 Vested and expected to vest at December 31, 2015 1,437,583 $ 6.19 8.94 $ 15,774 Vested at December 31, 2015 809,879 $ 2.82 8.38 $ 11,615 Exercisable at December 31, 2015 1,114,318 $ 5.19 8.98 $ 13,342 The following table summarizes the Black-Scholes option pricing model assumptions used to estimate the fair value of stock options granted to employees under our equity incentive plans and the shares purchasable under our 2015 ESPP during the periods presented: For the years ended December 31, 2015 2014 2015 EIP Risk-free interest rate 1.53% - 1.91% 0.04% - 1.98% Expected dividend yield 0% 0% Expected volatility 78% - 80% 71% - 78% Expected term (years) 5.00 - 6.08 5.00 - 6.08 2015 ESPP Risk-free interest rate 0.35% - 0.94% - Expected dividend yield 0% - Expected volatility 65% - 101% - Expected term (years) 0.50 - 2.00 - Stock-based compensation expense recognized for stock options and the ESPP has been reported in the statements of operations and comprehensive loss as follows (in thousands): Years ended December 31, 2015 2014 Research and development $ 1,586 $ 108 General and administrative 1,447 124 Total $ 3,033 $ 232 The weighted-average grant date fair value of stock options granted to employees during the year ended December 31, 2015 was $5.81 per share. The total grant date fair value of stock options that vested during the year ended December 31, 2015 was $2.2 million. As of December 31, 2015, total unrecognized share-based compensation expense related to unvested employee stock options of the Company was approximately $4.7 million. This unrecognized compensation cost is expected to be recognized over a weighted-average period of approximately 2.7 years. As of December 31, 2015, total unrecognized compensation expense related to the Company’s ESPP was approximately $0.5 million. This unrecognized compensation cost is expected to be recognized over approximately 1.9 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in common stock equivalent shares): Years ended December 31, 2015 2014 Conversion of Series A preferred - 3,839,604 Stock options issued and outstanding 1,437,583 709,136 Authorized for future stock awards 1,788,396 12,062 Awards available under the ESPP 226,004 - Total 3,451,983 4,560,802

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	9. INCOME TAXES The Company accounts for income taxes under ASC 740. Deferred income tax assets and liabilities are determined based upon differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The following table provides a reconciliation between income taxes computed at the federal statutory rate of 34% and the provision for income taxes (in thousands): Years Ended December 31, 2015 2014 2013 Federal income taxes at 34% $ (10,946 ) $ (4,044 ) $ (457 ) State income tax, net of federal benefit (1,821 ) (672 ) (62 ) Tax effect on nondeductible expenses 341 132 80 Research credits (676 ) (265 ) (18 ) Change in valuation allowance 13,084 4,849 457 Other 18 - - Income tax expense $ - $ - $ - Significant components of the Company’s net deferred tax assets are as follows (in thousands): Years Ended December 31, 2015 2014 2013 Deferred tax assets: Net operating losses $ 15,646 $ 4,187 $ 433 Research credits 987 283 - Intangibles 590 635 - Other 1,231 226 49 Total deferred tax assets 18,454 5,331 482 Less valuation allowance (18,454 ) (5,331 ) (482 ) Income tax expense $ - $ - $ - At December 31, 2015, the Company had federal and state net operating loss carryforwards of approximately $39.3 million and $39.4 million, respectively. The federal and state loss carryforwards begin to expire in 2033, unless previously utilized. The Company also has federal and state research and development credit carryforwards totaling $1.0 million and $0.5 million, respectively. The federal research and development credit carryforwards begin to expire in 2033, unless previously utilized. The state research and development credit carryforwards begin to expire in 2028. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Based on the weight of all evidence, including a history of operating losses, management has determined that it is more likely than not that the net deferred tax assets will not be realized. A valuation allowance of $18.5 million and $5.3 million as of December 31, 2015 and 2014, respectively, has been established to offset the deferred tax assets as realization of such assets is uncertain. Future utilization of the Company’s net operating loss and research and development credits carryforwards to offset future taxable income may be subject to an annual limitation, pursuant to Internal Revenue Code (IRC) Sections 382 and 383, as a result of ownership changes that may have occurred or that could occur in the future. An ownership change occurs when a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has not completed an IRC Section 382/383 analysis regarding the limitation of net operating loss and research and development credit carryforwards. The Company recognizes a tax benefit from an uncertain tax position 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 the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. At December 31, 2015 and 2014, the unrecognized tax benefits recorded were approximately $356,000 and $108,000, respectively. Approximately $318,000 and $94,000 of the unrecognized tax benefits for the years ended December 31, 2015 and 2014, respectively, would reduce our annual effective tax rates, if recognized, subject to the valuation allowances. The Company does not anticipate a significant change in the unrecognized tax benefits within the next 12 months. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for 2015, 2014 and 2013 is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance as of the beginning of the year $ 108 $ 6 $ - Increases related to current year tax positions 248 102 6 Balance as of the end of the year $ 356 $ 108 $ 6 The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by the United States and state jurisdictions where applicable. There are currently no pending income tax examinations. The Company’s tax years from inception in 2012 are subject to examination by the federal and state tax authorities due to the carryforward of unutilized net operating losses and research and development credits. The Company’s practice is to recognize interest and penalties related to income tax matters in income tax expense. The Company has not recognized interest or penalties since inception.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. COMMITMENTS AND CONTINGENCIES Litigation —From time to time, the Company may be involved in various lawsuits, legal proceedings, or claims that arise in the ordinary course of business. Management believes there are no claims or actions pending against the Company at December 31, 2015 which will have, individually or in the aggregate, a material adverse effect on its business, liquidity, financial position, or results of operations. Litigation, however, is subject to inherent uncertainties, and an adverse result in such matters may arise from time to time that may harm the Company’s business. Lease Obligations —In June 2014, the Company entered into an operating lease agreement for laboratory and office space in San Diego, California. Amendments for additional space were entered into in February 2015, March 2015 and August 2015. The lease expires in December 2018 with options for two individual two-year extensions. The lease is subject to charges for common area maintenance and other costs, and base rent is subject to 3% annual increases every July. Rent expense is being recorded on a straight-line basis over the life of the lease. Future minimum payments required under the lease as of December 31, 2015 are summarized as follows (in thousands): 2016 $ 704 2017 725 2018 747 Total minimum lease payments $ 2,176 Rent expense was $581,000 and $182,000 for the years ended December 31, 2015 and 2014, respectively. Contractual Obligations —The Company enters into contracts in the normal course of business with vendors for research and development activities, manufacturing, and professional services. These contracts generally provide for termination either on or within 30 days of notice.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	11. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Operating expenses $ 6,732 $ 6,446 $ 9,207 $ 9,928 Other income (expense) (5 ) 32 33 60 Net loss (6,737 ) (6,414 ) (9,174 ) (9,868 ) Basic and diluted net loss per share $ (5.92 ) $ (0.59 ) $ (0.67 ) $ (0.72 ) Shares used to compute basic and diluted net loss per share 1,138,911 10,957,150 13,674,568 13,731,519 2014 Operating expenses $ 559 $ 3,095 $ 3,320 $ 4,649 Other income (expense) (148 ) (124 ) 1 - Net loss (707 ) (3,219 ) (3,319 ) (4,649 ) Basic and diluted net loss per share $ (1.81 ) $ (5.04 ) $ (2.98 ) $ (4.13 ) Shares used to compute basic and diluted net loss per share 389,839 638,272 1,113,439 1,126,707

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The accompanying financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has experienced net losses and negative cash flows from operating activities since its inception. At December 31, 2015, the Company had an accumulated deficit of $45.5 million. The Company expects to continue to incur net losses into the foreseeable future. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company plans to continue to fund its losses from operations and capital funding needs through debt and equity financing or through collaborations or partnerships with other companies. Debt or equity financing or collaborations and partnerships with other companies may not be available on a timely basis on terms acceptable to the Company, or at all. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects.
Use of Estimates	Use of Estimates —The preparation of financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s financial statements relate to estimating the fair value of the Company’s common shares used to account for share-based compensation and certain accruals, including those related to preclinical and clinical activities. Although the estimates are based on the Company’s knowledge of current events, comparable companies, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Segment Information	Segment Information —Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.
Cash and Cash Equivalents	Cash and Cash Equivalents —The Company considers all short-term investments purchased with a maturity of three months or less when acquired to be cash equivalents.
Investments Available-for-Sale	Investments Available-for-Sale — Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Securities with maturity dates of 12 months or less from the date of purchase are classified as short-term investments and securities with maturity dates of more than 12 months are classified as long-term investments.
Property and Equipment	Property and Equipment — We carry our property and equipment at cost, which consists of lab equipment, computer equipment and software, office equipment, furniture and fixtures and leasehold improvements. Property and equipment is depreciated using the straight-line method over the estimated useful lives (generally three to seven years). Leasehold improvements are amortized over the lesser of their useful life or the remaining lease term, including any renewal periods that are deemed to be reasonably assured. Repair and maintenance costs are expensed as incurred.
Concentration of Credit Risk	Concentration of Credit Risk —The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. Periodically, the Company maintains deposits in government insured financial institutions in excess of government insured limits. The Company invests its cash balances in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to significant credit risk.
Patent Costs	Patent Costs — The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications) and such costs are included in general and administrative expenses in the accompanying statements of operations.
Convertible Preferred Stock	Convertible Preferred Stock —The Company’s Series A preferred and Series B preferred were classified as temporary equity instead of stockholders’ equity (deficit) in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities as the stock was conditionally redeemable at the holder’s option upon certain change in control events that were outside the Company’s control, including the liquidation, sale, or transfer of control of the Company. All of the outstanding Series A Preferred and Series B Preferred was converted to common upon the IPO in April 2015.
Income Taxes	Income Taxes —The Company follows the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes , or ASC 740, in reporting deferred income taxes. The ASC 740 requires a company to recognize deferred tax assets and liabilities for expected future income tax consequences of events that have been recognized in the Company’s financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740, which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes.
Research and Development Costs	Research and Development Costs —Research and development expenses consist of wages, benefits and stock-based compensation charges for research and development employees, scientific consultant fees, facilities and overhead expenses, laboratory supplies, manufacturing expenses, and preclinical and clinical trial costs. The Company accrues clinical trial expenses based on work performed which relies on estimates of total costs incurred based on patient enrollment, completion of studies, and other events. Costs incurred in purchasing technology assets and intellectual property are charged to research and development expense if the technology has not been conclusively proven to be feasible and has no alternative future use.
Comprehensive Loss	Comprehensive Loss —Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. The Company’s only component of other comprehensive loss is unrealized gains (losses) on short-term marketable securities. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss and as a separate component of the statements of convertible preferred stock and stockholders’ equity (deficit) for all periods presented.
Stock-based Compensation	Stock-based Compensation — The Company accounts for stock-based compensation expense related to employee stock options, restricted stock grants, and employee stock purchase plan rights by estimating the fair value on the date of grant using the Black-Scholes option pricing model. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized ratably over the requisite service period of the awards, net of estimated forfeitures. The Company accounts for stock options granted to non-employees using the fair value approach. These option grants are subject to periodic revaluation over their vesting terms.
Net Loss Per Share	Net Loss Per Share —Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, convertible notes payable, unvested restricted common stock subject to repurchase, and options outstanding under the Company’s stock option plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding. The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares): December 31, 2015 2014 Convertible preferred stock - 3,839,604 Common stock options issued and outstanding 1,437,583 709,136 Common stock subject to repurchase 156,235 361,768 Total 1,593,818 4,910,508
Fair Value of Financial Instruments	Fair Value of Financial Instruments — The Company follows authoritative guidance with respect to fair value reporting issued by the FASB for financial assets and liabilities, which defines fair value, provides guidance for measuring fair value and requires certain disclosures. The guidance does not apply to measurements related to share-based payments. The guidance discusses valuation techniques such as the market approach (comparable market prices), the income approach (present value of future income or cash flow), and the cost approach (cost to replace the service capacity of an asset or replacement cost). The guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The Company’s financial instruments consist of cash and cash equivalents, marketable securities, prepaid expenses, accounts payable, and accrued liabilities. Fair value estimates of these instruments are made at a specific point in time based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amount of cash and cash equivalents, prepaid expenses, accounts payable, and accrued liabilities are generally considered to be representative of their respective fair values because of the short-term nature of those instruments. The fair value of marketable securities is based upon market prices quoted on the last day of the fiscal period or other observable market inputs.
Recently Issued Accounting Standards	Recently Issued Accounting Standards — During 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-15, “Presentation of Financial Statements—Going Concern.” The update requires management to assess an entity’s ability to continue as a going concern and to provide related footnote disclosure in certain circumstances. The update is effective for annual reporting periods ending after December 15, 2016 and interim periods thereafter. Early application is permitted. The Company is currently assessing the impact that this standard will have on its financial statements. During 2015, the FASB issued ASU 2015-17, “Income Taxes: Balance Sheet Classification of Deferred Taxes,” which amends existing guidance to require companies to classify deferred tax assets and liabilities as noncurrent in the statement of financial position. The update is effective for annual periods beginning after December 15, 2016, and early adoption is permitted. The update may be adopted on either a prospective or retrospective basis. The Company adopted ASU 2015-17 in the fourth quarter of 2015 on a retrospective basis. The adoption of this guidance did not have a material impact on the Company’s financial statements. During 2016, the FASB issued ASU 2016-02, “Leases,” which requires that lease arrangements longer than 12 months result in an entity recognizing an asset and liability. The updated guidance is effective for interim and annual periods beginning after December 15, 2018, and early adoption is permitted. The Company is currently assessing the impact that this standard will have on its financial statements.

Summary of Significant Accoun20

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares): December 31, 2015 2014 Convertible preferred stock - 3,839,604 Common stock options issued and outstanding 1,437,583 709,136 Common stock subject to repurchase 156,235 361,768 Total 1,593,818 4,910,508

Short-Term Investments (Tables)

Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following table summarizes the available-for-sale securities held at December 31, 2015 (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value Certificates of deposit $ 20,000 $ - $ - $ 20,000 Commercial paper 24,960 - (8 ) $ 24,952 Total $ 44,960 $ - $ (8 ) $ 44,952

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis: TOTAL LEVEL 1 LEVEL 2 LEVEL 3 December 31, 2015 Assets: Cash equivalents and money market funds $ 12,353 $ 12,353 $ - $ - Certificates of deposit included in cash and cash equivalents 50,000 - 50,000 - Certificates of deposit included in short-term investments 20,000 - 20,000 - Commercial paper 24,952 - 24,952 - Total assets at fair value $ 107,305 $ 12,353 $ 94,952 $ - December 31, 2014 Assets: Cash equivalents and money market funds $ 20,769 $ 20,769 $ - $ - Total assets at fair value $ 20,769 $ 20,769 $ - $ -

Property and Equipment (Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): December 31, 2015 2014 Laboratory equipment $ 1,438 $ 687 Leasehold improvements 425 94 Computer hardware and software 242 210 Office equipment 111 42 Furniture and fixtures 105 9 2,321 1,042 Less accumulated depreciation and amortization (637 ) (179 ) Total $ 1,684 $ 863

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Text Block [Abstract]
Schedule of Stock Option Activity	The following table summarizes stock option activity during the year ended December 31, 2015: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value Outstanding at December 31, 2014 709,136 $ 2.29 9.73 $ 2,522 Options granted 899,728 8.56 Options exercised (67,468 ) 2.40 Options canceled (103,813 ) 2.58 Outstanding at December 31, 2015 1,437,583 $ 6.19 8.94 $ 15,774 Vested and expected to vest at December 31, 2015 1,437,583 $ 6.19 8.94 $ 15,774 Vested at December 31, 2015 809,879 $ 2.82 8.38 $ 11,615 Exercisable at December 31, 2015 1,114,318 $ 5.19 8.98 $ 13,342
Summary of black-scholes option pricing model assumptions used to estimate fair value of stock options granted to employees under equity incentive plans and shares purchasable under 2015 ESPP	The following table summarizes the Black-Scholes option pricing model assumptions used to estimate the fair value of stock options granted to employees under our equity incentive plans and the shares purchasable under our 2015 ESPP during the periods presented: For the years ended December 31, 2015 2014 2015 EIP Risk-free interest rate 1.53% - 1.91% 0.04% - 1.98% Expected dividend yield 0% 0% Expected volatility 78% - 80% 71% - 78% Expected term (years) 5.00 - 6.08 5.00 - 6.08 2015 ESPP Risk-free interest rate 0.35% - 0.94% - Expected dividend yield 0% - Expected volatility 65% - 101% - Expected term (years) 0.50 - 2.00 -
Summary of Stock-based compensation expense recognized for stock options and ESPP	Stock-based compensation expense recognized for stock options and the ESPP has been reported in the statements of operations and comprehensive loss as follows (in thousands): Years ended December 31, 2015 2014 Research and development $ 1,586 $ 108 General and administrative 1,447 124 Total $ 3,033 $ 232
Summary of common stock reserved for future issuance	Common stock reserved for future issuance is as follows (in common stock equivalent shares): Years ended December 31, 2015 2014 Conversion of Series A preferred - 3,839,604 Stock options issued and outstanding 1,437,583 709,136 Authorized for future stock awards 1,788,396 12,062 Awards available under the ESPP 226,004 - Total 3,451,983 4,560,802

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Reconciliation Between Federal Statutory and Provision For Income Taxes	The following table provides a reconciliation between income taxes computed at the federal statutory rate of 34% and the provision for income taxes (in thousands): Years Ended December 31, 2015 2014 2013 Federal income taxes at 34% $ (10,946 ) $ (4,044 ) $ (457 ) State income tax, net of federal benefit (1,821 ) (672 ) (62 ) Tax effect on nondeductible expenses 341 132 80 Research credits (676 ) (265 ) (18 ) Change in valuation allowance 13,084 4,849 457 Other 18 - - Income tax expense $ - $ - $ -
Schedule of Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets are as follows (in thousands): Years Ended December 31, 2015 2014 2013 Deferred tax assets: Net operating losses $ 15,646 $ 4,187 $ 433 Research credits 987 283 - Intangibles 590 635 - Other 1,231 226 49 Total deferred tax assets 18,454 5,331 482 Less valuation allowance (18,454 ) (5,331 ) (482 ) Income tax expense $ - $ - $ -
Schedule of Reconciliation Amount of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for 2015, 2014 and 2013 is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance as of the beginning of the year $ 108 $ 6 $ - Increases related to current year tax positions 248 102 6 Balance as of the end of the year $ 356 $ 108 $ 6

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum payments required under the lease as of December 31, 2015 are summarized as follows (in thousands): 2016 $ 704 2017 725 2018 747 Total minimum lease payments $ 2,176

Selected Quarterly Financial 27

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Data (Unaudited)	First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Operating expenses $ 6,732 $ 6,446 $ 9,207 $ 9,928 Other income (expense) (5 ) 32 33 60 Net loss (6,737 ) (6,414 ) (9,174 ) (9,868 ) Basic and diluted net loss per share $ (5.92 ) $ (0.59 ) $ (0.67 ) $ (0.72 ) Shares used to compute basic and diluted net loss per share 1,138,911 10,957,150 13,674,568 13,731,519 2014 Operating expenses $ 559 $ 3,095 $ 3,320 $ 4,649 Other income (expense) (148 ) (124 ) 1 - Net loss (707 ) (3,219 ) (3,319 ) (4,649 ) Basic and diluted net loss per share $ (1.81 ) $ (5.04 ) $ (2.98 ) $ (4.13 ) Shares used to compute basic and diluted net loss per share 389,839 638,272 1,113,439 1,126,707

The Company and Basis of Pres28

The Company and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands	Apr. 20, 2015USD ($)$ / sharesshares	Apr. 02, 2015	Dec. 31, 2015USD ($)Segmentshares	Dec. 31, 2014USD ($)shares
Business Description And Basis Of Presentation [Line Items]
Reverse split of common stock		Company’s board of directors and stockholders approved a 1-for-25.4 reverse stock split
Reverse stock split ratio		0.039370
Common stock, shares issued			13,942,520	1,494,506
Accumulated deficit | $			$ (45,497)	$ (13,304)
Number of Operating Segments | Segment			1
Common Stock
Business Description And Basis Of Presentation [Line Items]
Convertible preferred stock in to shares of common stock	7,561,380
Initial Public Offering
Business Description And Basis Of Presentation [Line Items]
Common stock, shares issued	4,800,000
Sale of common stock, price per share | $ / shares	$ 16
Net proceeds from sale of common stock | $	$ 69,300

Summary of Significant Accoun29

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2015
Minimum
Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	3 years
Maximum
Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	7 years

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded in the calculation of diluted net loss per share	1,593,818	4,910,508
Convertible preferred stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded in the calculation of diluted net loss per share		3,839,604
Common Stock Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded in the calculation of diluted net loss per share	1,437,583	709,136
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded in the calculation of diluted net loss per share	156,235	361,768

Short-Term Investments - Summar

Short-Term Investments - Summary of Available-for-Sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 44,960,000
Unrealized Losses	(8,000)
Fair Value	44,952,000	$ 0
Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	20,000,000
Fair Value	20,000,000
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	24,960,000
Unrealized Losses	(8,000)
Fair Value	$ 24,952,000

Short-Term Investments - Additi

Short-Term Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Investments Debt And Equity Securities [Abstract]
Maturity Period of Short Term Investments	All available-for-sale securities held at December 31, 2015 will mature in less than one year.
Fair Value	$ 44,952,000	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - Fair Value, Measurements, Nonrecurring - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets	$ 0	$ 0
Fair value of liabilities	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - Fair Value Measurements Recurring Basis - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Assets:
Total assets at fair value	$ 107,305	$ 20,769
Cash Equivalents and Money Market Funds
Assets:
Total assets at fair value	12,353	20,769
Certificates of Deposit Included in Cash and Cash Equivalents
Assets:
Total assets at fair value	50,000
Certificates of Deposit Included in Short-Term Marketable Securities
Assets:
Total assets at fair value	20,000
Commercial Paper
Assets:
Total assets at fair value	24,952
Level 1
Assets:
Total assets at fair value	12,353	20,769
Level 1 | Cash Equivalents and Money Market Funds
Assets:
Total assets at fair value	12,353	$ 20,769
Level 2
Assets:
Total assets at fair value	94,952
Level 2 | Certificates of Deposit Included in Cash and Cash Equivalents
Assets:
Total assets at fair value	50,000
Level 2 | Certificates of Deposit Included in Short-Term Marketable Securities
Assets:
Total assets at fair value	20,000
Level 2 | Commercial Paper
Assets:
Total assets at fair value	$ 24,952

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 2,321	$ 1,042
Less accumulated depreciation and amortization	(637)	(179)
Total	1,684	863
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,438	687
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	425	94
Computer Hardware and Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	242	210
Office Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	111	42
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 105	$ 9

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Depreciation and amortization of property and equipment	$ 461	$ 179

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	May. 30, 2014	Feb. 28, 2014	Jan. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
2013 Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Convertible notes issued				$ 1,250,000
Interest rate				8.00%
Conversion discount rate				15.00%
Proceeds from sale of equity securities				$ 13,750,000
Notes maturity date					Feb. 8, 2014
Notes extended maturity date					Jul. 30, 2014
2014 Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Convertible notes issued		$ 450,000	$ 500,000
Interest rate		8.00%	8.00%
Conversion discount rate		15.00%	15.00%
Notes maturity date					Jul. 30, 2014
2014 Convertible Notes Payable [Member] | Series A Convertible Preferred Stock
Debt Instrument [Line Items]
Debt Conversion, Converted Instrument, Shares Issued	321,492

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	12 Months Ended
	Dec. 31, 2015USD ($)Voteshares	Dec. 31, 2014shares
Equity [Abstract]
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	200,000,000	185,000,000
Number of votes entitlement for each share held | Vote	1
Preferred stock, amount of preferred dividends in arrears or default | $	$ 0

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	3,451,983	4,560,802
Weighted average grant date fair values of stock options granted	$ 5.81
Grant date fair value of stock options, vested	$ 2,200,000
Unrecognized share-based compensation expense of unvested employee stock options	$ 4,700,000
Unvested stock options, Unrecognized cost expected to be recognized, Recognition Period	2 years 8 months 12 days
2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance			245,168
Automatic annual increase in shares authorized for issuance in equity incentive plan	1.00%
Equity incentive plan, description	In addition, the number of shares of stock available for issuance under the ESPP will be automatically increased each January 1, beginning on January 1, 2016, by the lesser of (i) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, or (ii) 490,336 shares.
Price of stock option as percentage of estimated fair value of shares on date of grant	85.00%
Percentage of employee payroll deduction under the stock plan	15.00%
Number of share issued from ESPP	19,164
Unvested stock options, Unrecognized cost expected to be recognized, Recognition Period	1 year 10 months 24 days
Unrecognized share-based compensation expense of unvested employee stock options	$ 500,000
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting terms	4 years
Cash received on stock options	$ 341,000	$ 736,000
Unvested shares subject to repurchase by the Company	156,235
Maximum | 2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares outstanding	490,336
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	1,788,396		1,829,020
Automatic annual increase in shares authorized for issuance in equity incentive plan	4.00%
Equity incentive plan, description	The number of shares of stock available for issuance under the 2015 EIP will be automatically increased each January 1, beginning on January 1, 2016, by 4% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 or such lesser number as determined by the Company’s board of directors
Stock options grant period from date of grant	10 years
Price of stock option as percentage of estimated fair value of shares on date of grant	100.00%
2015 Equity Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting terms	3 years
2015 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting terms	4 years
2015 Equity Incentive Plan | More than 10% of voting power
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Price of stock option as percentage of estimated fair value of shares on date of grant	110.00%

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Stock Option Activity (Details) - Employee Stock Option - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, beginning balance	709,136
Number of stock options, granted	899,728
Number of Shares, Options exercised	(67,468)
Number of Shares, Options canceled	(103,813)
Number of Shares, Outstanding ending balance	1,437,583	709,136
Number of Shares, Vested and expected to vest	1,437,583
Number of Shares, Vested	809,879
Number of Shares, Exercisable	1,114,318
Weighted Average Exercise Price, Outstanding, beginning balance	$ 2.29
Weighted Average Exercise Price, Options granted	8.56
Weighted Average Exercise Price, Options exercised	2.40
Weighted Average Exercise Price, Options canceled	2.58
Weighted Average Exercise Price, Outstanding, ending balance	6.19	$ 2.29
Weighted Average Exercise Price, Vested and expected to vest	6.19
Weighted Average Exercise Price, Vested	2.82
Weighted Average Exercise Price, Exercisable	$ 5.19
Weighted Average Remaining Contractual Life in Years, Outstanding	8 years 11 months 9 days	9 years 8 months 23 days
Weighted Average Remaining Contractual Life in Years, Vested and expected to vest	8 years 11 months 9 days
Weighted Average Remaining Contractual Life in Years, Vested	8 years 4 months 21 days
Weighted Average Remaining Contractual Life in Years, Exercisable	8 years 11 months 23 days
Total Aggregate Intrinsic Value, Outstanding, beginning balance	$ 2,522
Total Aggregate Intrinsic Value, Outstanding, ending balance	15,774	$ 2,522
Total Aggregate Intrinsic Value, Vested and expected to vest	15,774
Total Aggregate Intrinsic Value, Vested	11,615
Total Aggregate Intrinsic Value, Exercisable	$ 13,342

Equity Incentive Plans - Summ41

Equity Incentive Plans - Summary of Black-Scholes Option Pricing Model Assumptions Used to Estimate Fair Value of Stock Options Granted to Employees Under Equity Incentive Plans and Shares Purchasable Under 2015 ESPP (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	1.53%	0.04%
Risk-free interest rate, Maximum	1.91%	1.98%
Expected dividend yield	0.00%	0.00%
Expected volatility, Minimum	78.00%	71.00%
Expected volatility, Maximum	80.00%	78.00%
2015 Equity Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years	5 years
2015 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 29 days	6 years 29 days
2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	0.35%
Risk-free interest rate, Maximum	0.94%
Expected dividend yield	0.00%
Expected volatility, Minimum	65.00%
Expected volatility, Maximum	101.00%
2015 Employee Stock Purchase Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 months
2015 Employee Stock Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	2 years

Equity Incentive Plans - Summ42

Equity Incentive Plans - Summary of Stock-Based Compensation Expense Recognized for Stock Options and ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 3,033	$ 232
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,586	108
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,447	$ 124

Equity Incentive Plans - Summ43

Equity Incentive Plans - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	3,451,983	4,560,802
Series A Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		3,839,604
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options issued and outstanding	1,437,583	709,136
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	1,788,396	12,062
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	226,004

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Effective income tax reconciliation at federal statutory rate	34.00%
Deferred tax assets, valuation allowance	$ 18,454,000	$ 5,331,000	$ 482,000
Unrecognized tax benefits	356,000	108,000	$ 6,000	$ 0
Unrecognized tax benefits that would impact on effective tax rate	$ 318,000	$ 94,000
Minimum
Income Tax Contingency [Line Items]
Expected cumulative change in ownership percentage	50.00%
Maximum
Income Tax Contingency [Line Items]
Expected cumulative change in ownership period	3 years
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 39,300,000
Operating loss carryforwards expiration starting year	2,033
Tax credit carryforwards, research and development	$ 1,000,000
Federal | Research and development
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration starting year, research and development	2,033
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 39,400,000
Operating loss carryforwards expiration starting year	2,033
Tax credit carryforwards, research and development	$ 500,000
State | Research and development
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration starting year, research and development	2,028

Income Taxes - Reconciliation B

Income Taxes - Reconciliation Between Income Taxes Computed at Federal Statutory Rate and Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal income taxes at 34%	$ (10,946)	$ (4,044)	$ (457)
State income tax, net of federal benefit	(1,821)	(672)	(62)
Tax effect on nondeductible expenses	341	132	80
Research credits	(676)	(265)	(18)
Change in valuation allowance	13,084	4,849	457
Other	18
Income tax expense	$ 0	$ 0	$ 0

Income Taxes - Reconciliation46

Income Taxes - Reconciliation Between Income Taxes Computed at Federal Statutory Rate and Provision for Income Taxes (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax reconciliation at federal statutory rate	34.00%

Income Taxes - Significant Comp

Income Taxes - Significant Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating losses	$ 15,646	$ 4,187	$ 433
Research credits	987	283
Intangibles	590	635
Other	1,231	226	49
Total deferred tax assets	18,454	5,331	482
Less valuation allowance	(18,454)	(5,331)	(482)
Income tax expense	$ 0	$ 0	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Unrecognized tax benefits
Balance as of the beginning of the year	$ 108,000	$ 6,000	$ 0
Increases related to current year tax positions	248,000	102,000	6,000
Balance as of the end of the year	$ 356,000	$ 108,000	$ 6,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2015USD ($)ClaimsOption	Dec. 31, 2014USD ($)
Commitments And Contingencies Disclosure [Abstract]
Number of claims and actions pending | Claims	0
Description of lease arrangements, operating leases	The lease expires in December 2018 with options for two individual two-year extensions.
Number of operating lease options for extension | Option	2
Operating lease expiration date	Dec. 31, 2018
Operating leases renewal term per options for extension	2 years
Annual increase in base rent	3.00%
Lease rent expense | $	$ 581,000	$ 182,000
Contractual obligation, contract termination notice period	30 days

Commitments and Contingencies50

Commitments and Contingencies - Schedule of Future Minimum Lease Payment (Details) $ in Thousands	Dec. 31, 2015USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2,016	$ 704
2,017	725
2,018	747
Total minimum lease payments	$ 2,176

Schedule of Selected Quarterly

Schedule of Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Operating expenses	$ 9,928	$ 9,207	$ 6,446	$ 6,732	$ 4,649	$ 3,320	$ 3,095	$ 559	$ 32,313	$ 11,623	$ 1,082
Other income (expense)	60	33	32	(5)		1	(124)	(148)	120	(271)	(262)
Net loss	$ (9,868)	$ (9,174)	$ (6,414)	$ (6,737)	$ (4,649)	$ (3,319)	$ (3,219)	$ (707)	$ (32,193)	$ (11,894)	$ (1,344)
Basic and diluted net loss per share	$ (0.72)	$ (0.67)	$ (0.59)	$ (5.92)	$ (4.13)	$ (2.98)	$ (5.04)	$ (1.81)	$ (3.25)	$ (14.51)	$ (4.15)
Shares used to compute basic and diluted net loss per share	13,731,519	13,674,568	10,957,150	1,138,911	1,126,707	1,113,439	638,272	389,839	9,920,382	819,868	323,689