Adverum Biotechnologies (ADVM) 10-Q 9 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	AAVL
Entity Registrant Name	Avalanche Biotechnologies, Inc.
Entity Central Index Key	1,501,756
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		25,759,330

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 200,676	$ 159,404
Marketable securities	68,210
Prepaid expenses and other current assets	1,475	874
Total current assets	270,361	160,278
Property and equipment, net	3,330	1,085
Deposit and other long-term assets	138	543
Total assets	273,829	161,906
Current liabilities:
Accounts payable	1,141	951
Accrued expenses and other current liabilities	3,734	3,707
Deferred rent, current portion	58
Deferred revenue, current portion	1,563	813
Total current liabilities	6,496	5,471
Long-term liabilities:
Deferred rent, net of current portion	466	306
Deferred revenue, net of current portion	4,537	6,646
Total liabilities	$ 11,499	$ 12,423
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 5,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.0001 par value, 300,000,000 shares authorized at September 30, 2015 and December 31, 2014; 25,756,057 and 22,754,037 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	$ 3	$ 2
Additional paid-in capital	332,404	186,186
Accumulated other comprehensive income	(3)	10
Accumulated deficit	(70,074)	(36,715)
Total stockholders’ equity	262,330	149,483
Total liabilities and stockholders’ equity	$ 273,829	$ 161,906

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	25,756,057	22,754,037
Common stock, shares outstanding	25,756,057	22,754,037

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Collaboration revenue	$ 953	$ 204	$ 1,359	$ 369
Operating expenses:
Research and development	7,523	5,746	18,270	9,750
General and administrative	7,631	2,398	16,733	4,618
Total operating expenses	15,154	8,144	35,003	14,368
Operating loss	(14,201)	(7,940)	(33,644)	(13,999)
Other (expense) income
Interest expense				(18)
Other (expense) income, net	117	(26)	285	(33)
Change in fair value of warrant liabilities		(290)		(759)
Loss on extinguishment of related-party convertible notes				(204)
Total other (expense) income, net	117	(316)	285	(1,014)
Net loss	(14,084)	(8,256)	(33,359)	(15,013)
Deemed dividend				(3,230)
Net loss attributable to common stockholders	(14,084)	(8,256)	(33,359)	(18,243)
Other comprehensive loss:
Net unrealized gain on marketable securities	2		12
Foreign currency translation adjustment	(17)	(15)	(25)	(16)
Comprehensive loss	$ (14,099)	$ (8,271)	$ (33,372)	$ (15,029)
Net loss per share attributable to common stockholders-basic and diluted	$ (0.55)	$ (0.50)	$ (1.31)	$ (2.29)
Weighted-average common shares outstanding-basic and diluted	25,685	16,394	25,378	7,960

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net loss	$ (33,359,000)	$ (15,013,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	506,000	83,000
Stock-based compensation expense	7,084,000	4,442,000
Non-cash interest expense		18,000
Amortization of premium on marketable securities	570,000
Change in fair value of warrant liabilities		759,000
Loss on extinguishment of related-party convertible notes		204,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(542,000)	(703,000)
Deposit	(1,000)	55,000
Accounts payable	283,000	127,000
Accrued expenses and other current liabilities	388,000	1,587,000
Deferred revenue	(1,359,000)	7,662,000
Deferred rent	218,000	186,000
Net cash used in operating activities	(26,212,000)	(593,000)
Cash flows from investing activities:
Purchases of marketable securities	(88,427,000)
Maturities of marketable securities	19,600,000
Purchases of property and equipment	(2,804,000)	(579,000)
Net cash used in investing activities	(71,631,000)	(579,000)
Cash flows from financing activities:
Proceeds from public offering of common stock, net	138,954,000	106,973,000
Proceeds from issuance of Series B convertible preferred stock		52,905,000
Expenses related to issuance of Series B convertible preferred stock		(2,540,000)
Proceeds from issuance of convertible notes		2,000,000
Repurchase of Series A convertible preferred stock		(4,000,000)
Proceeds from exercises of warrants		606,000
Proceeds from issuance of common stock pursuant to option exercises	181,000	3,000
Net cash provided by financing activities	139,135,000	165,947,000
Effect of foreign currency exchange rate on cash and cash equivalents	(20,000)	(10,000)
Net increase in cash and cash equivalents	41,272,000	164,765,000
Cash and cash equivalents at beginning of period	159,404,000	564,000
Cash and cash equivalents at end of period	200,676,000	165,329,000
Supplemental schedule of noncash investing and financing information
Conversion of related-party convertible notes payable to convertible preferred stock		2,000,000
Warrants issued in connection with issuance of Series B convertible preferred stock		266,000
Warrants issued in connection with license agreements		42,000
Fixed assets in accounts payable and current liabilities	$ 182,000	252,000
Deferred initial public offering expenses in accounts payable and current liabilities		520,000
Collaborative Partner [Member]
Cash flows from financing activities:
Proceeds from sales of common stock		$ 10,000,000

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Avalanche Biotechnologies, Inc. (the “Company”, “we” or “us”) was incorporated in Delaware on July 17, 2006, and is headquartered in Menlo Park, California. The Company is a biopharmaceutical company committed to improving or preserving the sight of people with serious eye diseases with an unmet medical need. Since the Company’s inception, it has devoted its efforts principally to performing research and development activities, including early clinical trials, filing patent applications, obtaining regulatory approvals, hiring personnel, and raising capital to support these activities. The Company has not generated any revenue from the sale of products since its inception. The Company has experienced net losses since its inception and has an accumulated deficit of $70.1 million as of September 30, 2015. The Company expects to incur losses and have negative net cash flows from operating activities as it expands its portfolio and engages in further research and development activities, particularly conducting preclinical studies and clinical trials. The Company believes that it has sufficient funds to continue operations for the foreseeable future. Initial Public Offering —On August 5, 2014, the Company completed its initial public offering (IPO) of shares of its common stock. As a result, the following transactions were recorded in the Company’s consolidated financial statements on August 5, 2014 (the third quarter of 2014): • the sale of 6,900,000 shares of common stock, including 900,000 from the exercise by the underwriters of their option to purchase additional shares, at an offering price of $17.00 per share, for net proceeds of $106.5 million, after deducting the underwriters’ discounts, commissions and offering expenses; • concurrent with the IPO, the private placement of 588,235 shares of common stock to Regeneron Pharmaceuticals, Inc. (Regeneron), pursuant to the Regeneron agreement signed in May 2014, at the offering price of $17.00 per share for gross proceeds of $10.0 million and no underwriting discounts or commissions; • immediately prior to the completion of the IPO, all the outstanding shares of the Company’s convertible preferred stock were converted into 10,689,027 shares of common stock; and • immediately prior to the completion of the IPO, all outstanding warrants for convertible preferred stock and common stock were exercised into 407,131 shares of common stock for proceeds of $0.6 million. Follow-on Offerings —In January 2015, the Company completed a public offering of 2,369,375 shares of its common stock (Follow-on Offering), which included 359,918 shares the Company issued pursuant to the underwriters’ exercise of their option to purchase additional shares, and the Company received net proceeds of approximately $130.6 million, after underwriting discounts, commissions and offering expenses. In March 2015, (i) the Company received net proceeds of approximately $8.3 million, after discounts and other issuance costs, which resulted from the sale of 230,000 common shares, and (ii) the Company issued 230,000 common shares to a shareholder that exercised warrants prior to the initial public offering. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and following the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s consolidated financial information. The results of operations for the nine month period ended September 30, 2015 are not necessarily indicative of the results to be expected for the full year or any other future period. The balance sheet as of December 31, 2014 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 filed with the SEC.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 2 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Cash and Cash Equivalents —The Company considers all highly liquid investments purchased with original maturities of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include cash held in banks and money market accounts. Cash equivalents are stated at fair value. Marketable Securities —All marketable securities, which consist of debt securities and certificates of deposit, have been classified as “available for sale” and are carried at fair value. Unrealized gains and losses, net of any related tax effects, are excluded from earnings and are included in other comprehensive loss and reported as a separate component of stockholders’ equity until realized. 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), net. The cost of securities sold is based on the specific-identification method. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Interest on short-term investments is included in interest income. In accordance with the Company’s investment policy, management invests to diversify credit risk and only invests in securities with high credit quality, including U.S. government securities. The Company regularly evaluates whether declines in the fair value of its investments below their cost are other than temporary. The evaluation includes consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities, and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. If the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other than temporary, the Company would reduce the carrying value of the security it holds and records a loss for the amount of such decline. The Company has not recorded any realized losses or declines in value judged to be other than temporary on its investments. Revenue Recognition - In connection with the research collaboration and license agreement, Regeneron acquired a time-limited right of first negotiation for a potential license to develop and commercialize AVA-101. The Company recognized $0.8 million during the third quarter of 2015 and will recognize the remaining $0.7 million during the fourth quarter of 2015, the period when Regeneron has exclusive access to the results of the Phase 2a clinical trial. Recently Issued Accounting Pronouncements —In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern , requiring management to evaluate whether events or conditions could impact an entity’s ability to continue as a going concern and to provide disclosures if necessary. Management will be required to perform the evaluation within one year after the date that the financial statements are issued. Disclosures will be required if conditions give rise to substantial doubt and the type of disclosure will be determined based on whether management’s plans will be able to alleviate the substantial doubt. The accounting standards update will be effective for the first annual period ending after December 15, 2016, and for annual periods and interim periods thereafter with early application permitted. The adoption of this ASU is not expected to impact the Company’s financial position or results of operations. In May 2014, the FASB issued ASU No. 2014-09 , Revenue from Contracts with Customers Revenue Recognition

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities	9 Months Ended
	Sep. 30, 2015
Cash And Cash Equivalents [Abstract]
Cash Equivalents and Marketable Securities	3. Cash Equivalents and Marketable Securities The following is a summary of the cash equivalents and marketable securities: September 30, 2015 Amortized Cost Basis Unrealized Gains Unrealized Loses Estimated Fair Value Money Market Funds $ 191,024 $ — $ — $ 191,024 Certificates of Deposit 4,080 2 — 4,082 U.S. Treasury Securities 25,158 9 — 25,167 U.S. Government Agency Securities 38,960 2 (1 ) 38,961 259,222 13 (1 ) 259,234 Less: Cash Equivalents (191,024 ) — — (191,024 ) Total Marketable Securities $ 68,198 $ 13 $ (1 ) $ 68,210 The Company did not hold any available-for-sale securities as of December 31, 2014. As of September 30, 2015, the contractual maturities of the Company’s marketable securities were less than one year. Management determined that the gross unrealized losses of $1,000 on the Company’s marketable securities as of September 30, 2015 were temporary in nature. The Company currently does not intend to sell these securities prior to maturity and does not consider these investments to be other-than-temporarily impaired at September 30, 2015. There were no sales of available-for-sale securities in any of the periods presented.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements and Fair Value of Financial Instruments	4. Fair Value Measurements and Fair Value of Financial Instruments The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 : Quoted prices in active markets for identical assets or liabilities. Level 2 : Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 : Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The fair value of Level 1 securities are determined using quoted prices in active markets for identical assets. Level 1 securities consist of highly liquid money market funds. Financial assets and liabilities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis. U.S. Treasury securities, U.S. government agency securities and certificate of deposit are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2. The Company’s financial instruments had consisted of Level 3 liabilities. In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. Level 3 liabilities that were measured at estimated fair value on a recurring basis consisted of common and preferred stock warrant liabilities. The estimated fair values of the outstanding common and preferred stock warrant liabilities are measured using the Black-Scholes valuation model. This method of valuation involves using such inputs as the estimated fair value of the underlying stock at the measurement date, the expected term, which is the remaining contractual term of the warrants, risk-free interest rates, expected dividends on stock and expected volatility of the price of the underlying stock. Due to the nature of these inputs, the valuation of the warrants is considered a Level 3 measurement. The convertible preferred stock and common stock warrant liabilities will increase or decrease each period based on the fluctuations of the fair value of the underlying security. A significant fluctuation in the common or convertible preferred stock fair value would result in a material change in the fair values of the convertible preferred stock and common stock warrant liabilities. During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at estimated fair value using Level 3 inputs. There were no transfers within the hierarchy during the year ended December 31, 2014 and the nine months ended September 30, 2015. As of December 31, 2014 and September 30, 2015, the Company had no Level 3 assets or liabilities. The following table summarizes, for assets recorded at fair value, the respective fair value and the classification by level of input within the fair value hierarchy as described above (in thousands): Quoted Prices Significant Other Significant Total In Observable Inputs Unobservable Inputs Carrying Value (Level 1) (Level 2) (Level 3) September 30, 2015 Assets: Money Market Funds $ 191,024 $ 191,024 $ — $ — Certificates of Deposit 4,082 — 4,082 — U.S. Treasury Securities 25,167 — 25,167 — U.S. Government Agency Securities 38,961 — 38,961 — Total Cash Equivalents and Marketable Securities $ 259,234 $ 191,024 $ 68,210 $ — December 31, 2014 Assets: Money Market Funds $ 40,000 $ 40,000 $ — $ — Total Cash Equivalents $ 40,000 $ 40,000 $ — $ — The following table provides a summary of changes in the estimated fair value of the Company’s warrants liabilities and embedded derivative liability measured at estimated fair value using significant Level 3 inputs (in thousands): Convertible Preferred Stock Common Stock Warrant Liability (1) Warrant Liability (2) Balance as of January 1, 2014 $ 91 $ 42 Issuance of common stock warrant — (41 ) Change in fair value 760 (1 ) Exercises (851 ) — Balance as of September 30, 2014 $ — $ — (1) In July 2014, all of the outstanding warrants to purchase convertible preferred stock and common stock were exercised immediately prior to the completion of the initial public offering (IPO). (2) In March 2014, the common stock warrant was issued and was recorded to additional paid-in capital. All of the warrants to purchase common stock and preferred stock were exercised for cash in connection with the completion of the IPO in August 2014, resulting in the issuance of an aggregate of 407,131 shares of common stock in exchange for proceeds of $0.6 million. As a result of the exercises of the warrants to purchase preferred stock, the Company recorded a $0.8 million loss related to the change in fair value in our consolidated statements of operations and comprehensive loss and reclassified the fair value of $0.9 million to permanent equity. The fair value of the warrants to purchase preferred stock was calculated using the Black-Scholes valuation model, and was based on the common stock fair value of $17.00 per share, contractual term of the warrants of 1.1 years, a risk-free interest rate of 0.1%, an expected volatility of 70% and a 0% expected dividend yield.

Significant Agreements

Significant Agreements	9 Months Ended
	Sep. 30, 2015
Research And Development [Abstract]
Significant Agreements	5. Significant Agreements University of California —In May 2010, the Company entered into a license agreement, as amended, with the Regents of the University of California (Regents) for exclusive rights in the U.S. to certain patents owned by the Regents. Under the terms of the agreement, the Company paid an upfront license fee of $100,000 and agreed to reimburse the Regents for patent-related expenses. The Company is obligated to pay the Regents royalties on net sales, if any, as well as an annual maintenance fee of $50,000 beginning in the calendar year after the first commercial sale of a licensed product and milestone payments related to the achievement of certain clinical and regulatory goals totaling up to $900,000 for the first indication and $500,000 for each additional indication for up to two additional indications. Through September 30, 2015, none of these goals had been achieved, and no milestones were payable.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2015
Property Plant And Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, Net Property and equipment, net consists of the following (in thousands): September 30, 2015 December 31, 2014 Computer equipment and software $ 257 $ 142 Laboratory equipment 2,890 1,012 Furniture and fixtures 528 73 Leasehold improvements 351 48 Total property and equipment 4,026 1,275 Less accumulated depreciation and amortization (696 ) (190 ) Property and equipment, net $ 3,330 $ 1,085 Depreciation and amortization expense related to property and equipment for the three months ended September 30, 2015 and 2014 was $241,000 and $49,000, respectively. Depreciation and amortization expense related to property and equipment for the nine months ended September 30, 2015 and 2014 was $506,000 and $83,000, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2015
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	7. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following (in thousands): September 30, 2015 December 31, 2014 Employees' compensation $ 2,414 $ 1,509 Accrued professional and preclinical studies fees 1,109 1,236 Accrued clinical and process development costs 110 942 Other 101 20 Total accrued expenses and other current liabilities $ 3,734 $ 3,707

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Collaborations and License Agreements The Company is a party to various agreements, principally relating to licensed technology that requires future payments relating to milestones or royalties on future sales of specified products. Through September 30, 2015, none of the goals had been achieved under the license agreements and no cash milestones were accrued or payable. Because the achievement of these milestones is not fixed and determinable, such commitments have not been included in the Company’s condensed consolidated balance sheets. Guarantees and Indemnifications In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for indemnification for certain liabilities. The exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its directors and executive officers for specified events or occurrences, subject to some limits, while they are serving at the Company’s request in such capacities. There have been no claims to date and the Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company has not recorded any liabilities for these agreements as of September 30, 2015. Legal Proceedings From time to time, the Company may become involved in litigation and other legal actions. The Company estimates the range of liability related to any pending litigation where the amount and range of loss can be estimated. The Company records its best estimate of a loss when the loss is considered probable. Where a liability is probable and there is a range of estimated loss with no best estimate in the range, the Company records a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability had been incurred at the date of the financial statements and (ii) the range of loss can be reasonably estimated. In July 2015, three putative securities class action lawsuits were filed against the Company and certain of its officers in the United States District Court for the Northern District of California, each on behalf of a purported class of persons and entities who purchased or otherwise acquired our publicly traded securities between July 31, 2014 and June 15, 2015. The lawsuits assert claims under the Exchange Act and Securities Act and allege that the defendants made materially false and misleading statements and omitted allegedly material information related to, among other things, the Phase 2a clinical trial for AVA-101 and the prospects of AVA-101. The complaints seek unspecified damages, attorneys’ fees and other costs. The Company believes that the claims in the asserted actions are without merit and intend to defend the lawsuits vigorously. The Company expects to incur costs associated with defending the actions. While the Company has various insurance policies related to the risks associated with its business, including directors’ and officers’ liability insurance policies, there is no assurance that the Company will be successful in its defense of the actions, that its insurance coverage, which contains a self-insured retention, will be sufficient, or that its insurance carriers will cover all claims or litigation costs. Due to the inherent uncertainties of litigation, the Company cannot reasonably predict at this time the timing or outcomes of these matters or estimate the amount of losses, or range of losses, if any, or their effect, if any, on its consolidated financial statements.

Related-Party Convertible Notes

Related-Party Convertible Notes	9 Months Ended
	Sep. 30, 2015
Related Party Transactions [Abstract]
Related-Party Convertible Notes	9. Related-Party Convertible Notes On October 22, 2013, the Company entered into a convertible note purchase agreement with a related party investor for the issuance and sale of up to an aggregate principal amount of $5.0 million of convertible notes (2013 Notes). In each of January 2014 and April 2014, the Company borrowed an aggregate principal amount of $1.0 million of 2013 Notes. The difference between the fair value of the securities into which the debt was convertible and the effective conversion price on the borrowing date represents a beneficial conversion feature. In connection with the January 2014 and April 2014 borrowings, the Company recorded the fair value of the beneficial conversion feature of $1.0 million and $1.0 million, respectively, by allocating a portion of the proceeds to additional paid-in capital, resulting in a discount on the convertible instrument, to be amortized over the repayment period using the effective interest method. The 2013 Notes were converted to 295,115 shares of Series B convertible preferred stock in April 2014. At the time of the conversion, the Company recorded a $0.2 million loss on extinguishment of related-party convertible notes in the condensed consolidated statements of operations and comprehensive loss. At December 31, 2014 and September 30, 2015, there are no outstanding convertible notes recorded in the condensed consolidated balance sheets.

Stock Option Plans

Stock Option Plans	9 Months Ended
	Sep. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Plans	10. Stock Option Plans On December 26, 2006, the Company adopted the 2006 Equity Incentive Plan, which was amended by the board of directors on November 15, 2012 (2006 Plan). The 2006 Plan allowed for the granting of ISOs and NSOs to the employees, members of the board of directors and consultants of the Company. ISOs were granted only to the Company’s employees, including officers and directors who are also employees. NSOs were granted to the employees and consultants. In July 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Equity Incentive Award Plan (2014 Plan), effective upon the date upon which the registration statement for the IPO was declared effective, which was July 30, 2014. As of the date of the IPO, the Company reserved for issuance under the 2014 Plan a total of 2,088,332 shares of its common stock, plus any additional shares that would otherwise return to the 2006 Plan as a result of forfeiture, termination or expiration of awards previously granted under the 2006 Plan. Options may no longer be issued under the 2006 Plan after July 30, 2014. In addition, the 2014 Plan provides for annual increases in the number of shares available for issuance thereunder on the first business day of each fiscal year, beginning with 2015, equal to four percent (4%) of the number of shares of the Company’s common stock outstanding as of such date or a lesser number of shares as determined by the Company’s board of directors. As of September 30, 2015, a total of 8,454,368 shares of common stock were authorized for issuance and 1,669,510 shares were available for future grants under the 2014 Plan. Options under the 2014 Plan may be granted for periods of up to 10 years and at prices 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, however, that the exercise price of an ISO and NSO granted to a 10% shareholder may not be less than 110% of the estimated fair value of the shares on the date of grant. Options granted to employees and non-employees generally vest ratably over four years. In July 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Employee Stock Purchase Plan (2014 ESPP). The Company reserved for issuance 208,833 shares of its common stock and provided for annual increases in the number of shares available for issuance on the first business day of each fiscal year, beginning in 2015, equal to the lesser of one percent (1%) of the number of shares of the Company’s common stock outstanding as of such date or a number of shares as determined by the Company’s board of directors. During 2015, no shares were issued under the 2014 ESPP. A total of 436,373 shares of common stock have been reserved for issuance under the 2014 ESPP and were available for issuance under the 2014 ESPP as of September 30, 2015. The following table summarizes option activity under our stock plans and related information: WEIGHTED- NUMBER OF WEIGHTED- AVERAGE REMAINING AGGREGATE SHARE AVERAGE EXERCISE CONTRACTUAL LIFE INTRINSIC VALUE (a) (IN THOUSANDS) PRICE (IN YEARS) (IN THOUSANDS) Balance at January 1, 2015 4,932 $ 5.61 8.2 $ 238,653 Options granted 693 $ 38.80 Options exercised (395 ) $ 0.46 Options cancelled (236 ) $ 18.12 Balance at September 30, 2015 4,994 $ 10.04 7.8 24,896 Vested and expected to vest as of September 30, 2015 4,933 $ 9.91 7.7 24,778 Exercisable as of September 30, 2015 2,518 $ 2.80 7.1 17,249 (a) The aggregate intrinsic value is calculated as the difference between the option exercise price and the closing price of common stock of $8.24 per share as of September 30, 2015. The total intrinsic value of options exercised during the nine months ended September 30, 2015 and 2014 were $11.2 million and $6.4 million, respectively. The following table summarizes information with respect to stock options outstanding and currently exercisable and vested. As of September 30, 2015: OPTIONS OUTSTANDING OPTIONS EXERCISABLE AND VESTED WEIGHTED- WEIGHTED- NUMBER AVERAGE REMAINING NUMBER AVERAGE REMAINING RANGE OF OUTSTANDING CONTRACTUAL LIFE OUTSTANDING CONTRACTUAL LIFE EXERCISE PRICES (IN THOUSANDS) (IN YEARS) (IN THOUSANDS) (IN YEARS) $0.15-$0.27 2,646 6.7 1,981 6.6 $0.28-$2.95 433 8.4 164 8.4 $2.96-$11.50 520 8.7 165 8.7 $11.51-$35.00 829 9.0 189 8.9 $35.01-$58.92 566 9.5 19 9.3 The Company has recorded aggregate stock-based compensation expense related to the issuance of stock option awards to employees and nonemployees in the condensed consolidated statement of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Research and development $ 2,044 $ 2,600 $ 1,883 $ 3,806 General and administrative 3,708 456 5,201 636 Total share-based compensation $ 5,752 $ 3,056 $ 7,084 $ 4,442 Departure of Key Executive Officer Effective July 23, 2015, Thomas W. Chalberg, Jr., Ph.D., resigned as the Chief Executive Officer and President of the Company and as a member of the board of directors. In connection with Dr. Chalberg’s resignation and his engagement as a consultant and Scientific Advisor, Dr. Chalberg and the Company entered into a Separation Agreement and General Release, dated July 23, 2015 (the Separation Agreement). Under the Separation Agreement, Dr. Chalberg is providing consulting services to the Company and serving as a member of the Company’s Scientific Advisory Board until the first anniversary of July 23, 2015 (the consulting period). During the consulting period, subject to the terms and conditions of the Separation Agreement, Dr. Chalberg is paid a monthly fee at the same rate as his salary in effect prior to his resignation and is continuing to vest in outstanding equity awards held by him at the same rates in effect for such awards prior to his resignation. Shares of the Company’s common stock subject to his outstanding equity awards that were otherwise scheduled to vest following the expiration of the consulting period will not vest under any circumstances and were forfeited and cancelled on July 23, 2015. As a result, the Company recorded a one-time share-based payment charge of $2.4 million related to the cancellation of unvested stock options for the three months ended September 30, 2015. The weighted-average fair values of options granted during the nine months ended September 30, 2015 and 2014 were $23.92 and $6.21, respectively. Restricted Stock Units Restricted stock units, or RSUs, are share awards that entitle the holder to receive freely tradable shares of our common stock upon vesting. The fair value of RSUs is based upon the closing sales price of our common stock on the grant date. RSUs granted to employees generally vest over a two-to-four year period. The following table summarizes the RSUs activity under our stock plans and related information: Number of Weighted-Average Shares Grant-Date (in thousands) Fair Value (in dollars) Outstanding at December 31, 2014 — $ — Granted 845 $ 13.85 Vested and released (8 ) $ 10.01 Forfeited (17 ) $ 39.35 Outstanding at September 30, 2015 820 $ 13.35 There were no RSUs granted prior to April 2015. The weighted-average grant date fair value of RSUs granted was $13.85 per share during 2015. The total fair value of RSUs that vested was Stock Options Granted to Employees The fair value of each option issued to employees was estimated at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Option grants: Expected volatility 75 % 79 % 77 % 79 % Expected term (in years) 6.1 6.1 6.1 6.0 Expected dividend yield — — — — Risk-free interest rate 1.8 % 2.0 % 1.7 % 1.9 % As of September 30, 2015, there was $22.1 million of unrecognized stock-based compensation expense related to employees’ awards that is expected to be recognized over a weighted-average period of 3.0 years. Stock Options Granted to Non-Employees Stock-based compensation related to stock options granted to non-employees is measured and recognized as the stock options are earned. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered. The following weighted-average assumptions were used in estimating non-employees’ stock-based compensation expenses: Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Option grants: Expected volatility 71 % 80 % 74 % 79 % Expected term (in years) 2.5 7.0 4.1 7.4 Expected dividend yield — — — — Risk-free interest rate 0.7 % 2.1 % 1.0 % 2.3 % As of September 30, 2015, there was $1.8 million of unrecognized stock-based compensation expense related to non-employees’ awards that is expected to be recognized over a weighted-average period of 1.4 years. Fair Value of Common Stock In determining the exercise prices for options granted, the Company’s board of directors has considered the fair value of the common stock as of each grant date. Prior to the IPO, the fair value of the common stock underlying the stock options was determined by the board of directors at each award grant date based upon a variety of factors, including the results obtained from an independent third party valuation, the Company’s financial position and historical financial performance, the status of technological developments within the Company’s products, the composition and ability of the current management team, an evaluation or benchmark of the Company’s competition, the current business climate in the marketplace, the illiquid nature of the common stock, arm’s-length sales of the Company’s capital stock (including convertible preferred stock), the effect of the rights and preferences of the preferred shareholders and the prospects of a liquidity event, among others. After the completion of the Company’s IPO in August 2014, the fair value of the common stock is based on the closing price of the common stock on the date of grant.

401(k) Savings Plan

401(k) Savings Plan	9 Months Ended
	Sep. 30, 2015
Postemployment Benefits [Abstract]
401(k) Savings Plan	11. 401(k) Savings Plan The Company established a defined-contribution savings plan under Section 401(k) of the Code. The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pretax basis. For the three and nine months ended September 30, 2015, the Company contributed $0 and $0.1 million, respectively, to the 401(k) Plan. The amount of contributions that the Company made to the 401(k) Plan during 2014 was $25,000.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	12. Net Loss Per Share Attributable to Common Stockholders The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data): Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Net loss $ (14,084 ) $ (8,256 ) $ (33,359 ) $ (15,013 ) Deemed dividend — — — (3,230 ) Net loss attributable to common stockholders (14,084 ) (8,256 ) (33,359 ) (18,243 ) Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share: Net shares outstanding 25,685 16,394 25,378 7,960 Basic and diluted net loss per share attributable to common stockholders $ (0.55 ) $ (0.50 ) $ (1.31 ) $ (2.29 ) We have excluded stock options and RSUs to purchase approximately 5.8 million and 4.8 million shares of our common stock that were outstanding as of September 30, 2015 and 2014, respectively, in the computation of diluted net loss per share attributable to common stockholders because their effect was antidilutive.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2015
Subsequent Events [Abstract]
Subsequent Event	13. Subsequent Event Warrant On October 15, 2015, in connection with an amendment to the license agreement between the Company and the Lions Eye Institute (LEI), dated as of August 20, 2010, the Company issued to LEI a warrant to purchase 40,000 shares of common stock with an exercise price of $10.51 per share. This common stock warrant is exercisable immediately, and expires on October 15, 2020. Collaboration and license agreement with Regeneron In connection with the research collaboration and license agreement with Regeneron that was entered into in May 2014, Regeneron acquired a time-limited right of first negotiation for a potential license to develop and commercialize AVA-101. On November 2, 2015, Regeneron notified the Company that it is not exercising this right of first negotiation.

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents —The Company considers all highly liquid investments purchased with original maturities of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include cash held in banks and money market accounts. Cash equivalents are stated at fair value.
Marketable Securities	Marketable Securities —All marketable securities, which consist of debt securities and certificates of deposit, have been classified as “available for sale” and are carried at fair value. Unrealized gains and losses, net of any related tax effects, are excluded from earnings and are included in other comprehensive loss and reported as a separate component of stockholders’ equity until realized. 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), net. The cost of securities sold is based on the specific-identification method. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Interest on short-term investments is included in interest income. In accordance with the Company’s investment policy, management invests to diversify credit risk and only invests in securities with high credit quality, including U.S. government securities. The Company regularly evaluates whether declines in the fair value of its investments below their cost are other than temporary. The evaluation includes consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities, and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. If the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other than temporary, the Company would reduce the carrying value of the security it holds and records a loss for the amount of such decline. The Company has not recorded any realized losses or declines in value judged to be other than temporary on its investments.
Revenue Recognition	Revenue Recognition - In connection with the research collaboration and license agreement, Regeneron acquired a time-limited right of first negotiation for a potential license to develop and commercialize AVA-101. The Company recognized $0.8 million during the third quarter of 2015 and will recognize the remaining $0.7 million during the fourth quarter of 2015, the period when Regeneron has exclusive access to the results of the Phase 2a clinical trial.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements —In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern , requiring management to evaluate whether events or conditions could impact an entity’s ability to continue as a going concern and to provide disclosures if necessary. Management will be required to perform the evaluation within one year after the date that the financial statements are issued. Disclosures will be required if conditions give rise to substantial doubt and the type of disclosure will be determined based on whether management’s plans will be able to alleviate the substantial doubt. The accounting standards update will be effective for the first annual period ending after December 15, 2016, and for annual periods and interim periods thereafter with early application permitted. The adoption of this ASU is not expected to impact the Company’s financial position or results of operations. In May 2014, the FASB issued ASU No. 2014-09 , Revenue from Contracts with Customers Revenue Recognition

Cash Equivalents and Marketab20

Cash Equivalents and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2015
Cash And Cash Equivalents [Abstract]
Summary of Cash Equivalents and Marketable Securities	The following is a summary of the cash equivalents and marketable securities: September 30, 2015 Amortized Cost Basis Unrealized Gains Unrealized Loses Estimated Fair Value Money Market Funds $ 191,024 $ — $ — $ 191,024 Certificates of Deposit 4,080 2 — 4,082 U.S. Treasury Securities 25,158 9 — 25,167 U.S. Government Agency Securities 38,960 2 (1 ) 38,961 259,222 13 (1 ) 259,234 Less: Cash Equivalents (191,024 ) — — (191,024 ) Total Marketable Securities $ 68,198 $ 13 $ (1 ) $ 68,210

Fair Value Measurements and F21

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Financial Assets Measured and Recognized at Fair Value on Recurring Basis	The following table summarizes, for assets recorded at fair value, the respective fair value and the classification by level of input within the fair value hierarchy as described above (in thousands): Quoted Prices Significant Other Significant Total In Observable Inputs Unobservable Inputs Carrying Value (Level 1) (Level 2) (Level 3) September 30, 2015 Assets: Money Market Funds $ 191,024 $ 191,024 $ — $ — Certificates of Deposit 4,082 — 4,082 — U.S. Treasury Securities 25,167 — 25,167 — U.S. Government Agency Securities 38,961 — 38,961 — Total Cash Equivalents and Marketable Securities $ 259,234 $ 191,024 $ 68,210 $ — December 31, 2014 Assets: Money Market Funds $ 40,000 $ 40,000 $ — $ — Total Cash Equivalents $ 40,000 $ 40,000 $ — $ —
Summary of Changes in Estimated Fair Value of Warrants Liabilities and Embedded Derivative Liability	The following table provides a summary of changes in the estimated fair value of the Company’s warrants liabilities and embedded derivative liability measured at estimated fair value using significant Level 3 inputs (in thousands): Convertible Preferred Stock Common Stock Warrant Liability (1) Warrant Liability (2) Balance as of January 1, 2014 $ 91 $ 42 Issuance of common stock warrant — (41 ) Change in fair value 760 (1 ) Exercises (851 ) — Balance as of September 30, 2014 $ — $ — (1) In July 2014, all of the outstanding warrants to purchase convertible preferred stock and common stock were exercised immediately prior to the completion of the initial public offering (IPO). (2) In March 2014, the common stock warrant was issued and was recorded to additional paid-in capital.

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2015
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): September 30, 2015 December 31, 2014 Computer equipment and software $ 257 $ 142 Laboratory equipment 2,890 1,012 Furniture and fixtures 528 73 Leasehold improvements 351 48 Total property and equipment 4,026 1,275 Less accumulated depreciation and amortization (696 ) (190 ) Property and equipment, net $ 3,330 $ 1,085

Accrued Expenses and Other Cu23

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2015
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): September 30, 2015 December 31, 2014 Employees' compensation $ 2,414 $ 1,509 Accrued professional and preclinical studies fees 1,109 1,236 Accrued clinical and process development costs 110 942 Other 101 20 Total accrued expenses and other current liabilities $ 3,734 $ 3,707

Stock Option Plans (Tables)

Stock Option Plans (Tables)	9 Months Ended
	Sep. 30, 2015
Summary of Information with Respect to Stock Options Outstanding and Currently Exercisable and Vested	The following table summarizes information with respect to stock options outstanding and currently exercisable and vested. As of September 30, 2015: OPTIONS OUTSTANDING OPTIONS EXERCISABLE AND VESTED WEIGHTED- WEIGHTED- NUMBER AVERAGE REMAINING NUMBER AVERAGE REMAINING RANGE OF OUTSTANDING CONTRACTUAL LIFE OUTSTANDING CONTRACTUAL LIFE EXERCISE PRICES (IN THOUSANDS) (IN YEARS) (IN THOUSANDS) (IN YEARS) $0.15-$0.27 2,646 6.7 1,981 6.6 $0.28-$2.95 433 8.4 164 8.4 $2.96-$11.50 520 8.7 165 8.7 $11.51-$35.00 829 9.0 189 8.9 $35.01-$58.92 566 9.5 19 9.3
Stock-Based Compensation Expense Related to Issuance of Stock Option Awards to Employees and Nonemployees	The Company has recorded aggregate stock-based compensation expense related to the issuance of stock option awards to employees and nonemployees in the condensed consolidated statement of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Research and development $ 2,044 $ 2,600 $ 1,883 $ 3,806 General and administrative 3,708 456 5,201 636 Total share-based compensation $ 5,752 $ 3,056 $ 7,084 $ 4,442
Summary of Restricted Stock Units Activity	The following table summarizes the RSUs activity under our stock plans and related information: Number of Weighted-Average Shares Grant-Date (in thousands) Fair Value (in dollars) Outstanding at December 31, 2014 — $ — Granted 845 $ 13.85 Vested and released (8 ) $ 10.01 Forfeited (17 ) $ 39.35 Outstanding at September 30, 2015 820 $ 13.35
Schedule of Fair Value of Option Issued to Employees Valuation Assumptions	The fair value of each option issued to employees was estimated at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Option grants: Expected volatility 75 % 79 % 77 % 79 % Expected term (in years) 6.1 6.1 6.1 6.0 Expected dividend yield — — — — Risk-free interest rate 1.8 % 2.0 % 1.7 % 1.9 %
Non Employee Stock Option [Member]
Schedule of Non-Employees Stock Purchase Plan Valuation Assumptions	The following weighted-average assumptions were used in estimating non-employees’ stock-based compensation expenses: Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Option grants: Expected volatility 71 % 80 % 74 % 79 % Expected term (in years) 2.5 7.0 4.1 7.4 Expected dividend yield — — — — Risk-free interest rate 0.7 % 2.1 % 1.0 % 2.3 %
2006 and 2014 Equity Incentive Plan [Member]
Summary of Stock Options Activity	The following table summarizes option activity under our stock plans and related information: WEIGHTED- NUMBER OF WEIGHTED- AVERAGE REMAINING AGGREGATE SHARE AVERAGE EXERCISE CONTRACTUAL LIFE INTRINSIC VALUE (a) (IN THOUSANDS) PRICE (IN YEARS) (IN THOUSANDS) Balance at January 1, 2015 4,932 $ 5.61 8.2 $ 238,653 Options granted 693 $ 38.80 Options exercised (395 ) $ 0.46 Options cancelled (236 ) $ 18.12 Balance at September 30, 2015 4,994 $ 10.04 7.8 24,896 Vested and expected to vest as of September 30, 2015 4,933 $ 9.91 7.7 24,778 Exercisable as of September 30, 2015 2,518 $ 2.80 7.1 17,249 (a) The aggregate intrinsic value is calculated as the difference between the option exercise price and the closing price of common stock of $8.24 per share as of September 30, 2015.

Net Loss Per Share Attributab25

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data): Three Months Ended Nine Months Ended September 30, September 30, 2015 2014 2015 2014 Net loss $ (14,084 ) $ (8,256 ) $ (33,359 ) $ (15,013 ) Deemed dividend — — — (3,230 ) Net loss attributable to common stockholders (14,084 ) (8,256 ) (33,359 ) (18,243 ) Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share: Net shares outstanding 25,685 16,394 25,378 7,960 Basic and diluted net loss per share attributable to common stockholders $ (0.55 ) $ (0.50 ) $ (1.31 ) $ (2.29 )

Organization and Basis of Pre26

Organization and Basis of Presentation - Additional Information (Detail) - USD ($)	Aug. 05, 2014	Mar. 31, 2015	Jan. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Date of incorporation				Jul. 17, 2006
Accumulated deficit				$ (70,074,000)		$ (36,715,000)
Issuance of common stock		230,000	2,369,375
Net proceeds from initial public offering				$ 138,954,000	$ 106,973,000
Net proceeds from issuance of common stock		$ 8,300,000	$ 130,600,000
Conversion of preferred stock, common stock issued upon conversion	10,689,027
Warrants [Member]
Class of Stock [Line Items]
Conversion of warrants into shares of common stock, shares	407,131
Conversion of warrants into shares of common stock, value	$ 600,000
IPO [Member]
Class of Stock [Line Items]
Issuance of common stock	6,900,000
Issuance of common stock upon exercise of overallotment by underwriters	900,000
Common stock, shares issued, price per share	$ 17
Net proceeds from initial public offering	$ 106,500,000
Private Placement [Member]
Class of Stock [Line Items]
Issuance of common stock	588,235
Common stock, shares issued, price per share	$ 17
Net proceeds from issuance of common stock	$ 10,000,000
Underwriting discount or commissions	$ 0
Over-Allotment Option [Member]
Class of Stock [Line Items]
Issuance of common stock			359,918

Summary Of Significant Accoun27

Summary Of Significant Accounting Policies - Additional Information (Detail) - Regeneron Corporation [Member] - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Research collaboration and license agreement revenue		$ 0.8
Scenario Forecast [Member]
Summary Of Significant Accounting Policies [Line Items]
Research collaboration and license agreement revenue	$ 0.7

Cash Equivalents and Marketab28

Cash Equivalents and Marketable Securities - Summary of Cash Equivalents and Marketable Securities (Detail) $ in Thousands	Sep. 30, 2015USD ($)
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	$ 68,198
Unrealized Gains	13
Unrealized Loses	(1)
Estimated Fair Value	68,210
Less: Cash Equivalents, Amortized Cost Basis	(191,024)
Less: Cash Equivalents, Unrealized Gains	0
Less: Cash Equivalents, Unrealized Loses	0
Less: Cash Equivalents, Estimated Fair Value	(191,024)
Cash Equivalents And Marketable Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	259,222
Unrealized Gains	13
Unrealized Loses	(1)
Estimated Fair Value	259,234
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	191,024
Estimated Fair Value	191,024
Certificates of Deposit [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	4,080
Unrealized Gains	2
Estimated Fair Value	4,082
U.S. Treasury Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	25,158
Unrealized Gains	9
Estimated Fair Value	25,167
US Government Agency Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	38,960
Unrealized Gains	2
Unrealized Loses	(1)
Estimated Fair Value	$ 38,961

Cash Equivalents and Marketab29

Cash Equivalents and Marketable Securities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015USD ($)	Dec. 31, 2014Security
Cash And Cash Equivalents [Abstract]
Marketable securities, gross unrealized losses	$ 1,000
Number of available-for-securities held | Security		0
Contractual maturities of marketable securities	Less than one year
Proceeds from sales of available-for-sale securities	$ 0

Fair Value Measurements and F30

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	Aug. 05, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities transferred within Level 3			$ 0		$ 0
Total assets			$ 259,234,000		40,000,000
Change in fair value of warrant liabilities		$ (290,000)		$ (759,000)
Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Conversion of warrants into shares of common stock, shares	407,131
Conversion of warrants into shares of common stock, value	$ 600,000
Reclassified fair value of permanent equity	$ 900,000
Fair value of common stock price per share			$ 17
Contractual term of warrants			1 year 1 month 6 days
Fair value of obligation risk free interest rate			0.10%
Fair value of obligation expected volatility rate			70.00%
Fair value of obligation expected dividend yield			0.00%
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets			$ 0		0
Total liabilities			$ 0		$ 0

Fair Value Measurements and F31

Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets Measured and Recognized at Fair Value on Recurring Basis (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Assets:
Total assets	$ 259,234,000	$ 40,000,000
Money Market Funds [Member]
Assets:
Total assets	191,024,000	40,000,000
Certificates of Deposit [Member]
Assets:
Total assets	4,082,000
U.S. Treasury Securities [Member]
Assets:
Total assets	25,167,000
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Total assets	191,024,000	40,000,000
Quoted Prices in Active Markets (Level 1) [Member] | Money Market Funds [Member]
Assets:
Total assets	191,024,000	40,000,000
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	68,210,000
Significant Other Observable Inputs (Level 2) [Member] | Certificates of Deposit [Member]
Assets:
Total assets	4,082,000
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Securities [Member]
Assets:
Total assets	25,167,000
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total assets	0	$ 0
U.S. Government Agency Securities [Member]
Assets:
Total assets	38,961,000
U.S. Government Agency Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	$ 38,961,000

Fair Value Measurements and F32

Fair Value Measurements and Fair Value of Financial Instruments - Summary of Changes in Estimated Fair Value of Warrants Liabilities and Embedded Derivative Liability (Detail) - Warrants [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2014USD ($)
Series A and B Convertible Preferred Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 91
Change in fair value	760
Exercises	(851)
Common Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	42
Issuance of common stock warrant	(41)
Change in fair value	$ (1)

Significant Agreements - Additi

Significant Agreements - Additional Information (Detail) - University of California [Member] - USD ($)	1 Months Ended	9 Months Ended
	May. 31, 2010	Sep. 30, 2015
License Agreement [Line Items]
Upfront license fee paid	$ 100,000
Annual maintenance fee payable	50,000
Aggregate amount of milestone payments for first indication	900,000
Additional milestone payments for up to two additional indications	$ 500,000
Additional milestone payments recognized		$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 4,026	$ 1,275
Less accumulated depreciation and amortization	(696)	(190)
Property and equipment, net	3,330	1,085
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	257	142
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	2,890	1,012
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	528	73
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 351	$ 48

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 241,000	$ 49,000	$ 506,000	$ 83,000

Accrued Expenses and Other Cu36

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accrued Liabilities Current [Abstract]
Employees' compensation	$ 2,414	$ 1,509
Accrued professional and preclinical studies fees	1,109	1,236
Accrued clinical and process development costs	110	942
Other	101	20
Total accrued expenses and other current liabilities	$ 3,734	$ 3,707

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	9 Months Ended
	Jul. 31, 2015Claim	Sep. 30, 2015USD ($)Claim
Commitments And Contingencies Disclosure [Abstract]
Accrued royalties		$ 0
Claims paid to date related to indemnification issues		$ 0
Number of claims to date | Claim	3	0
Accruals or expenses related to indemnification issues		$ 0

Related-Party Convertible Not38

Related-Party Convertible Notes - Additional Information (Detail) - USD ($)	Aug. 05, 2014	Apr. 30, 2014	Jan. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Dec. 31, 2014	Oct. 22, 2013
Debt Instrument [Line Items]
Conversion of preferred stock, shares converted	10,689,027
Loss on extinguishment of related-party convertible notes				$ (204,000)
Outstanding convertible notes					$ 0	$ 0
2013 Notes [Member]
Debt Instrument [Line Items]
Aggregate principal borrowed amount of convertible notes		$ 1,000,000	$ 1,000,000
Fair value and repurchase of beneficial conversion feature		$ 1,000,000	$ 1,000,000
2013 Notes [Member] | Series B Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Conversion of preferred stock, shares converted		295,115
Loss on extinguishment of related-party convertible notes		$ 200,000
2013 Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Aggregate principal amount of convertible notes							$ 5,000,000

Stock Option Plans - Additional

Stock Option Plans - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted period		6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years
Total intrinsic value of options exercised				$ 11,200,000	$ 6,400,000
One time share based payment charge related to cancellation of unvested stock option of CEO		$ 2,400,000
Weighted-average fair values of options granted				$ 23.92	$ 6.21
Unrecognized stock-based compensation, weighted-average period				3 years
Unrecognized stock-based compensation expense related to employees' awards		22,100,000		$ 22,100,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU granted				845,000
Weighted-average grant date fair values of RSUs granted				$ 13.85
Total fair values of RSUs vested		100,000		$ 100,000
Unrecognized compensation cost related to unvested RSUs		$ 9,600,000		$ 9,600,000
Unrecognized stock-based compensation, weighted-average period				2 years 3 months 18 days
Restricted Stock Units [Member] | Prior to April 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU granted				0
Non Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted period		2 years 6 months	7 years	4 years 1 month 6 days	7 years 4 months 24 days
Unrecognized stock-based compensation, weighted-average period				1 year 4 months 24 days
Unrecognized stock-based compensation expense related to employees' awards		$ 1,800,000		$ 1,800,000
Maximum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted to employees vesting period				4 years
Minimum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted to employees vesting period				2 years
2014 Equity Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annual increase in number of shares available for future issuance	4.00%
Common stock shares authorized for issuance		8,454,368		8,454,368
Shares available for future grants		1,669,510		1,669,510
Stock options granted description				Options under the 2014 Plan may be granted for periods of up to 10 years and at prices 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, however, that the exercise price of an ISO and NSO granted to a 10% shareholder may not be less than 110% of the estimated fair value of the shares on the date of grant.
Stock options granted to employees and non-employees vesting period	4 years
2014 Equity Incentive Award Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted period	10 years
2014 Equity Incentive Award Plan [Member] | IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available for future grant	2,088,332
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available for future grant	208,833	436,373		436,373
Percentage increase in shares issued	1.00%
Common stock, shares issued				0

Stock Option Plans - Summary of

Stock Option Plans - Summary of Stock Options Activity (Detail) - 2006 Equity Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
NUMBER OF SHARES, Beginning Balance	4,932,000
NUMBER OF SHARES, Options granted	693,000
NUMBER OF SHARES, Options exercised	(395,000)
NUMBER OF SHARES, Options cancelled	(236,000)
NUMBER OF SHARES, Ending Balance	4,994,000	4,932,000
NUMBER OF SHARES, Vested and expected to vest	4,933,000
NUMBER OF SHARES, Exercisable	2,518,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
WEIGHTED-AVERAGE EXERCISE PRICE, Beginning Balance	$ 5.61
WEIGHTED-AVERAGE EXERCISE PRICE, Options granted	38.80
WEIGHTED-AVERAGE EXERCISE PRICE, Options exercised	0.46
WEIGHTED-AVERAGE EXERCISE PRICE, Options cancelled	18.12
WEIGHTED-AVERAGE EXERCISE PRICE, Ending Balance	10.04	$ 5.61
WEIGHTED-AVERAGE EXERCISE PRICE, Vested and expected to vest	9.91
WEIGHTED-AVERAGE EXERCISE PRICE, Exercisable	$ 2.80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	7 years 9 months 18 days	8 years 2 months 12 days
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS), Vested and expected to vest	7 years 8 months 12 days
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS), Exercisable	7 years 1 month 6 days
AGGREGATE INTRINSIC VALUE, Beginning Balance	$ 238,653
AGGREGATE INTRINSIC VALUE, Ending Balance	24,896	$ 238,653
AGGREGATE INTRINSIC VALUE, Vested and expected to vest	24,778
AGGREGATE INTRINSIC VALUE, Exercisable	$ 17,249

Stock Option Plans - Summary 41

Stock Option Plans - Summary of Stock Options Activity (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2015$ / shares
Equity [Abstract]
Aggregate intrinsic value of option per share	$ 8.24

Stock Option Plans - Summary 42

Stock Option Plans - Summary of Information with Respect to Stock Options Outstanding and Currently Exercisable and Vested (Detail)	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
RANGE OF EXERCISE PRICES, LOWER RANGE	$ 0.15
RANGE OF EXERCISE PRICES, UPPER PRICES	$ 0.27
OPTIONS OUTSTANDING, NUMBER OUTSTANDING | shares	2,646,000
OPTIONS OUTSTANDING, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	6 years 8 months 12 days
OPTIONS EXERCISABLE AND VESTED, NUMBER OUTSTANDING | shares	1,981,000
OPTIONS EXERCISABLE AND VESTED, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	6 years 7 months 6 days
Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
RANGE OF EXERCISE PRICES, LOWER RANGE	$ 0.28
RANGE OF EXERCISE PRICES, UPPER PRICES	$ 2.95
OPTIONS OUTSTANDING, NUMBER OUTSTANDING | shares	433,000
OPTIONS OUTSTANDING, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 4 months 24 days
OPTIONS EXERCISABLE AND VESTED, NUMBER OUTSTANDING | shares	164,000
OPTIONS EXERCISABLE AND VESTED, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 4 months 24 days
Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
RANGE OF EXERCISE PRICES, LOWER RANGE	$ 2.96
RANGE OF EXERCISE PRICES, UPPER PRICES	$ 11.50
OPTIONS OUTSTANDING, NUMBER OUTSTANDING | shares	520,000
OPTIONS OUTSTANDING, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 8 months 12 days
OPTIONS EXERCISABLE AND VESTED, NUMBER OUTSTANDING | shares	165,000
OPTIONS EXERCISABLE AND VESTED, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 8 months 12 days
Range 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
RANGE OF EXERCISE PRICES, LOWER RANGE	$ 11.51
RANGE OF EXERCISE PRICES, UPPER PRICES	$ 35
OPTIONS OUTSTANDING, NUMBER OUTSTANDING | shares	829,000
OPTIONS OUTSTANDING, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	9 years
OPTIONS EXERCISABLE AND VESTED, NUMBER OUTSTANDING | shares	189,000
OPTIONS EXERCISABLE AND VESTED, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 10 months 24 days
Range 5 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
RANGE OF EXERCISE PRICES, LOWER RANGE	$ 35.01
RANGE OF EXERCISE PRICES, UPPER PRICES	$ 58.92
OPTIONS OUTSTANDING, NUMBER OUTSTANDING | shares	566,000
OPTIONS OUTSTANDING, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	9 years 6 months
OPTIONS EXERCISABLE AND VESTED, NUMBER OUTSTANDING | shares	19,000
OPTIONS EXERCISABLE AND VESTED, WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	9 years 3 months 18 days

Stock Option Plans - Stock-Base

Stock Option Plans - Stock-Based Compensation Expense Related to Issuance of Stock Option Awards to Employees and Nonemployees (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 5,752	$ 3,056	$ 7,084	$ 4,442
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	2,044	2,600	1,883	3,806
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 3,708	$ 456	$ 5,201	$ 636

Stock Option Plans - Summary 44

Stock Option Plans - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units [Member]	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted | shares	845,000
Number of Shares, Vested and released | shares	(8,000)
Number of Shares, Forfeited | shares	(17,000)
Number of Shares, Ending Balance | shares	820,000
Weighted-Average Grant-Date Fair Value, Granted	$ 13.85
Weighted-Average Grant-Date Fair Value, Vested and released	10.01
Weighted-Average Grant-Date Fair Value, Forfeited	39.35
Weighted-Average Grant-Date Fair Value, Ending Balance	$ 13.35

Stock Option Plans - Schedule o

Stock Option Plans - Schedule of Employees Stock Purchase Plan Valuation Assumptions (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	75.00%	79.00%	77.00%	79.00%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years
Risk-free interest rate	1.80%	2.00%	1.70%	1.90%
Non Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	71.00%	80.00%	74.00%	79.00%
Expected term (in years)	2 years 6 months	7 years	4 years 1 month 6 days	7 years 4 months 24 days
Risk-free interest rate	0.70%	2.10%	1.00%	2.30%

401(k) Savings Plan - Additiona

401(k) Savings Plan - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Compensation And Retirement Disclosure [Abstract]
Contribution by company	$ 0	$ 100,000	$ 25,000

Net Loss Per Share Attributab47

Net Loss Per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net loss	$ (14,084)	$ (8,256)	$ (33,359)	$ (15,013)
Deemed dividend				(3,230)
Net loss attributable to common stockholders	$ (14,084)	$ (8,256)	$ (33,359)	$ (18,243)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share:
Net shares outstanding	25,685	16,394	25,378	7,960
Basic and diluted net loss per share attributable to common stockholders	$ (0.55)	$ (0.50)	$ (1.31)	$ (2.29)

Net Loss Per Share Attributab48

Net Loss Per Share Attributable to Common Stockholders - Additional Information (Detail) - shares shares in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	5.8	4.8

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - Subsequent Event [Member] - LEI [Member] - $ / shares	Oct. 15, 2015	Oct. 31, 2015
Subsequent Event [Line Items]
Warrant to purchase shares of common stock		40,000
Exercise price		$ 10.51
Warrant expiration date	Oct. 15, 2020