Adverum Biotechnologies (ADVM) 10-Q 6 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 29, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
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	Accelerated Filer
Entity Common Stock, Shares Outstanding		27,131,197

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 247,082	$ 221,348
Marketable securities		37,732
Receivable from collaborative partner	1,117	449
Prepaid expenses and other current assets	1,030	1,463
Total current assets	249,229	260,992
Property and equipment, net	3,565	3,187
Deposit and other long-term assets	140	140
Total assets	252,934	264,319
Current liabilities:
Accounts payable	486	605
Restructuring liabilities	49	1,013
Accrued expenses and other current liabilities	3,889	4,007
Deferred rent, current portion	73	66
Deferred revenue, current portion	1,059	883
Total current liabilities	5,556	6,574
Long-term liabilities:
Deferred rent, net of current portion	429	447
Deferred revenue, net of current portion	5,383	4,706
Total liabilities	$ 11,368	$ 11,727
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 March 31, 2016 and December 31, 2015; 27,094,955 and 25,858,722 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 3	$ 3
Additional paid-in capital	341,114	336,768
Accumulated other comprehensive income (loss)	9	(11)
Accumulated deficit	(99,560)	(84,168)
Total stockholders’ equity	241,566	252,592
Total liabilities and stockholders’ equity	$ 252,934	$ 264,319

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
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	27,094,955	25,858,722
Common stock, shares outstanding	27,094,955	25,858,722

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Collaboration revenue	$ 265	$ 203
Operating expenses:
Research and development	7,455	5,621
General and administrative	8,318	4,143
Total operating expenses	15,773	9,764
Operating loss	(15,508)	(9,561)
Other income
Other income, net	116	52
Total other income, net	116	52
Net loss	(15,392)	(9,509)
Other comprehensive loss:
Net unrealized gain (loss) on marketable securities	6	(35)
Foreign currency translation adjustment	14	(8)
Comprehensive loss	$ (15,372)	$ (9,552)
Net loss per share attributable to common stockholders-basic and diluted	$ (0.57)	$ (0.38)
Weighted-average common shares outstanding-basic and diluted	27,095	24,887

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (15,392)	$ (9,509)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	320	118
Stock-based compensation expense	4,084	773
Amortization of premium on marketable securities		59
Changes in operating assets and liabilities:
Accounts receivable	(668)
Prepaid expenses and other current assets	441	(120)
Deposit		(1)
Accounts payable	(140)	1,771
Accrued expenses and other current liabilities	(676)	(764)
Restructuring liabilities	(964)
Deferred revenue	853	(203)
Deferred rent	(11)	134
Net cash used in operating activities	(12,153)	(7,742)
Cash flows from investing activities:
Purchases of marketable securities		(88,370)
Maturities of marketable securities	37,738
Purchases of property and equipment	(122)	(411)
Net cash provided by (used in) investing activities	37,616	(88,781)
Cash flows from financing activities:
Proceeds from sales of common stock, net of offering cost		138,954
Proceeds from issuance of common stock pursuant to option exercises	262	21
Net cash provided by financing activities	262	138,975
Effect of foreign currency exchange rate on cash and cash equivalents	9	(7)
Net increase in cash and cash equivalents	25,734	42,445
Cash and cash equivalents at beginning of period	221,348	159,404
Cash and cash equivalents at end of period	247,082	201,849
Supplemental schedule of noncash investing and financing information
Fixed assets in accounts payable and current liabilities	$ 576	$ 278

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2016
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 gene therapy company committed to discovering and developing novel medicines that can offer potentially life-changing therapeutic benefit to patients suffering from chronic or debilitating disease. Since the Company’s inception, it has devoted its efforts principally to performing research and development activities, including conducting preclinical studies, 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 $99.6 million as of March 31, 2016. 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. The Company believes that it has sufficient funds to continue operations for the foreseeable future. On January 29, 2016, the Company entered into an acquisition agreement (the Agreement) with Annapurna Therapeutics SAS (Annapurna), a privately-held biopharmaceutical company focused on advancing gene therapy for unmet medical needs, certain shareholders of Annapurna (the Contributors), and Shareholder Representative Services LLC, a Colorado limited liability company, acting as the representative of the Contributors. Upon the terms and subject to the conditions described in the Agreement, the Company will acquire all of the issued and outstanding capital stock of Annapurna in exchange for approximately 13.1 million newly issued shares of the Company’s common stock (the Company Common Stock), and the outstanding options or other rights to purchase capital stock of Annapurna (the Annapurna Options) will be converted into options relating to approximately 4.7 million shares of the Company Common Stock (the Company Options) (together with the other transactions contemplated by the Agreement, the Transaction). Each Company Option will relate to the whole number of shares of Company Common Stock (rounded down to the nearest whole share) equal to the number of the shares of the common stock of Annapurna subject to such Annapurna Option multiplied by 9.5615 (as may be adjusted pursuant to the Agreement, the Exchange Ratio). The exercise price per share for the Company Option will be equal to the exercise price per share of such Annapurna Option divided by the Exchange Ratio. Holders of Annapurna Options may exercise their Annapurna Options prior to the closing of the transaction, in which case each such exercising holder will become party to the Agreement as a Contributor and receive newly issued shares of the Company’s common stock upon closing instead of Company Options. The issuance of new shares of the Company Common Stock in connection with the Transaction (the Company Stock Issuance) requires the Company’s stockholders’ vote and is expected to close in the second quarter of 2016. The Agreement may be terminated by either party under certain circumstances as defined in the Agreement, including, among others, if the closing of the acquisition has not occurred by the six-month anniversary of the execution of the Agreement, subject to certain exceptions, or if the Company’s stockholders fail to approve the Company Stock Issuance. The Agreement provides for the Company to pay to Annapurna a reverse termination fee of $4,000,000 if the Agreement is terminated by either party for the Company’s failure to obtain the required vote of the Company’s stockholders for the Company Stock Issuance or if the Agreement is terminated by Annapurna upon a certain defined triggering event. The Agreement also provides for the Company to pay to Annapurna a reverse termination fee of $6,000,000 (less the $4,000,000 reverse termination fee described above, if paid) if the Agreement is terminated by either party for the failure to obtain the required vote of the Company’s stockholders or by Annapurna upon certain other triggering events, and either (x) the Company consummates within twelve months of such termination an alternative transaction that was publicly announced or communicated in writing to the Company’s board of directors prior to such termination or (y) the Company consummates within six months of such termination an alternative transaction that is first publicly announced or otherwise communicated in writing to the Company’s board of directors following the termination of the Agreement while an alternative transaction described in the foregoing clause (x) remains outstanding and not withdrawn. 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 three month period ended March 31, 2016 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, 2015 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, 2015 filed with the SEC.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2016
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, 2015. Recently Issued Accounting Pronouncements — In May 2014, the Financial Accounting Standards Board ( FASB) issued Accounting Standard Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605 , Revenue Recognition . This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. Companies may adopt ASU 2014-09 using a full retrospective approach or report the cumulative effect as of the date of adoption. In July 2015, the FASB voted to approve a one-year deferral of the effective date to December 15, 2017 for interim and annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016 . The Company is evaluating the application of this ASU, but has not yet determined the potential effects it may have on the Company’s consolidated financial statements. In August 2014, the FASB issued 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 On January 5, 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-2, Leases In March 2016, the FASB issued ASU No. 2016-9, Compensation-Stock Compensation: Improvements to Employee Share-Based Payment Accounting The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or no material effect is expected on the consolidated financial statements as a result of future adoption.

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities	3 Months Ended
	Mar. 31, 2016
Cash And Cash Equivalents [Abstract]
Cash Equivalents and Marketable Securities	3. Cash Equivalents and Marketable Securities The Company did not hold any marketable securities as of March 31, 2016, all investments were held in money market funds and are treated as cash equivalents. The investments reported as of December 31, 2015 were all held until maturity and no realized gains or losses were recorded in the three months ended March 31, 2016. The following is a summary of the cash equivalents and marketable securities as of December 31, 2015: December 31, 2015 Amortized Cost Basis Unrealized Gains Unrealized Loses Estimated Fair Value Money Market Funds $ 208,588 $ — $ — $ 208,588 Certificates of Deposit 1,680 — — 1,680 U.S. Treasury Securities 15,046 — (4 ) 15,042 U.S. Government Agency Securities 21,012 — (2 ) 21,010 246,326 — (6 ) 246,320 Less: Cash Equivalents (208,588 ) — — (208,588 ) Total Marketable Securities $ 37,738 $ — $ (6 ) $ 37,732 As of December 31, 2015, the contractual maturities of the Company’s marketable securities were less than one year. The Company has not sold any securities prior to maturity and so does not consider any gains or losses on these investment to be other-than-temporarily impaired. 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	3 Months Ended
	Mar. 31, 2016
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. There were no transfers within the hierarchy during the three months ended March 31, 2016 and the year ended December 31, 2015. As of March 31, 2016 and December 31, 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 (Level 1) (Level 2) (Level 3) March 31, 2016 Assets: Money Market Funds - cash equivalent $ 241,663 $ 241,663 $ — $ — Total Cash Equivalents $ 241,663 $ 241,663 $ — $ — December 31, 2015 Assets: Money Market Funds - cash equivalent $ 208,588 $ 208,588 $ — $ — Certificates of Deposit 1,680 — 1,680 — U.S. Treasury Securities 15,042 — 15,042 — U.S. Government Agency Securities 21,010 — 21,010 — Total Cash Equivalents and Marketable Securities $ 246,320 $ 208,588 $ 37,732 $ —

Significant Agreements

Significant Agreements	3 Months Ended
	Mar. 31, 2016
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 March 31, 2016, none of these goals had been achieved, and no milestones were payable.

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2016
Property Plant And Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, Net Property and equipment, net consists of the following (in thousands): March 31, 2016 December 31, 2015 Computer equipment and software $ 237 $ 234 Laboratory equipment 3,157 3,041 Furniture and fixtures 552 552 Leasehold improvements 365 351 Construction in progress 565 — Total property and equipment 4,876 4,178 Less accumulated depreciation and amortization (1,311 ) (991 ) Property and equipment, net $ 3,565 $ 3,187 Depreciation and amortization expense related to property and equipment for the three months ended March 31, 2016 and 2015 was $320,000 and $118,000, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2016
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): March 31, 2016 December 31, 2015 Employees’ compensation expenses $ 1,077 $ 2,047 Accrued professional services 1,523 1,177 Accrued preclinical costs $ 731 $ 642 Accrued clinical and process development costs — 101 Other 558 40 Total accrued expenses and other current liabilities $ 3,889 $ 4,007

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
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 March 31, 2016, 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 March 31, 2016. 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 its publicly traded securities between July 31, 2014 and June 15, 2015. The lawsuits assert claims under the Securities Exchange Act of 1934 (Exchange Act) and the Securities Act of 1933, as amended (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. In December 2015, a putative securities class action lawsuit was filed against us, our board of directors, underwriters of our January 13, 2015, follow-on public stock offering, and two of our institutional stockholders, in the Superior Court of the State of California for the County of San Mateo. The complaint alleges that, in connection with our follow-on stock offering, the defendants violated the Securities Act by allegedly making materially false and misleading statements and by allegedly omitting material information related to the Phase 2a clinical trial for AVA-101 and the prospects of AVA-101. The complaint seeks unspecified compensatory and rescissory 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 condensed consolidated financial statements.

Stock Option Plans

Stock Option Plans	3 Months Ended
	Mar. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Plans	9. Stock Option Plans The Company’s 2014 Equity Incentive Award Plan (2014 Plan) permits the issuance of stock options (options), restricted stock units (RSUs) and other types of awards to employees, directors, and consultants. As of March 31, 2016, a total of 9,488,716 shares of common stock were authorized for issuance and 2,306,155 shares were available for future grants under the 2014 Plan. In July 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Employee Stock Purchase Plan (2014 ESPP). During the three months ended March 31, 2016 and 2015, no shares were issued under the 2014 ESPP. A total of 675,383 shares of common stock have been reserved for issuance under the 2014 ESPP and were available for issuance under the 2014 ESPP as of March 31, 2016. 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 PRICE (IN YEARS) (IN THOUSANDS) Balance at January 1, 2016 5,494 $ 8.75 7.8 $ 28,618 Options granted 386 $ 4.80 Options exercised (1,160 ) $ 0.42 Options cancelled (252 ) $ 23.39 Balance at March 31, 2016 4,468 $ 9.74 8.1 9,004 Vested and expected to vest as of March 31, 2016 4,419 $ 9.70 8.1 8,971 Exercisable as of March 31, 2016 1,969 $ 6.41 7.2 6,822 (a) The aggregate intrinsic value is calculated as the difference between the option exercise price and the closing price of common stock of $5.17 per share as of March 31, 2016. The weighted-average fair values of options granted during the three months ended March 31, 2016 and 2015 were $3.29 and $34.00, respectively. The total intrinsic value of options exercised during the three months ended March 31, 2016 and 2015 were $6.0 million and $4.4 million, respectively. 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 March 31, 2016 2015 Research and development $ 2,228 $ 284 General and administrative 1,856 489 Total share-based compensation $ 4,084 $ 773 During the three months ended March 31, 2016, stock-based compensation expense included additional expenses for the acceleration of awards relating to executive separation agreements with two employees. Stock-based compensation expense for these modifications was $1.4 million and $0.8 million for R&D and G&A, 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, 2015 632 $ 13.07 Granted 880 $ 4.83 Vested and released (124 ) $ 7.20 Forfeited (148 ) $ 7.19 Outstanding at March 31, 2016 1,240 $ 7.45 There were no RSUs granted prior to April 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 March 31, 2016 2015 Option grants: Expected volatility 80 % 78 % Expected term (in years) 6.0 6.1 Expected dividend yield — — Risk-free interest rate 1.4 % 1.8 % As of March 31, 2016, there was $21.0 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 March 31, 2016 2015 Option grants: Expected volatility 89 % 80 % Expected term (in years) 3.3 7.7 Expected dividend yield — — Risk-free interest rate 1.1 % 1.7 % As of March 31, 2016, there was $0.6 million of unrecognized stock-based compensation expense related to non-employees’ awards that is expected to be recognized over a weighted-average period of 0.9 years.

401(k) Savings Plan

401(k) Savings Plan	3 Months Ended
	Mar. 31, 2016
Postemployment Benefits [Abstract]
401(k) Savings Plan	10. 401(k) Savings Plan The Company established a defined-contribution savings plan under Section 401(k) of the Code (the 401(k) Plan. 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 months ended March 31, 2016 and 2015, the Company contributed $0.3 million and $0.1 million to the 401 (k) Plan, respectively.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	11. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period. Diluted net loss per share attributable is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. Diluted net loss per share is the same as basic net loss per share for all periods presented, since the effects of potentially dilutive securities are antidilutive. We have excluded stock options and RSUs to purchase approximately 5.7 million and 5.0 million shares of our common stock that were outstanding as of March 31, 2016 and 2015, respectively, in the computation of diluted net loss per share attributable to common stockholders because their effect was antidilutive.

Summary of Significant Accoun17

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements — In May 2014, the Financial Accounting Standards Board ( FASB) issued Accounting Standard Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605 , Revenue Recognition . This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. Companies may adopt ASU 2014-09 using a full retrospective approach or report the cumulative effect as of the date of adoption. In July 2015, the FASB voted to approve a one-year deferral of the effective date to December 15, 2017 for interim and annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016 . The Company is evaluating the application of this ASU, but has not yet determined the potential effects it may have on the Company’s consolidated financial statements. In August 2014, the FASB issued 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 On January 5, 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-2, Leases In March 2016, the FASB issued ASU No. 2016-9, Compensation-Stock Compensation: Improvements to Employee Share-Based Payment Accounting The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or no material effect is expected on the consolidated financial statements as a result of future adoption.

Cash Equivalents and Marketab18

Cash Equivalents and Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2016
Cash And Cash Equivalents [Abstract]
Summary of Cash Equivalents and Marketable Securities	The following is a summary of the cash equivalents and marketable securities as of December 31, 2015: December 31, 2015 Amortized Cost Basis Unrealized Gains Unrealized Loses Estimated Fair Value Money Market Funds $ 208,588 $ — $ — $ 208,588 Certificates of Deposit 1,680 — — 1,680 U.S. Treasury Securities 15,046 — (4 ) 15,042 U.S. Government Agency Securities 21,012 — (2 ) 21,010 246,326 — (6 ) 246,320 Less: Cash Equivalents (208,588 ) — — (208,588 ) Total Marketable Securities $ 37,738 $ — $ (6 ) $ 37,732

Fair Value Measurements and F19

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
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 (Level 1) (Level 2) (Level 3) March 31, 2016 Assets: Money Market Funds - cash equivalent $ 241,663 $ 241,663 $ — $ — Total Cash Equivalents $ 241,663 $ 241,663 $ — $ — December 31, 2015 Assets: Money Market Funds - cash equivalent $ 208,588 $ 208,588 $ — $ — Certificates of Deposit 1,680 — 1,680 — U.S. Treasury Securities 15,042 — 15,042 — U.S. Government Agency Securities 21,010 — 21,010 — Total Cash Equivalents and Marketable Securities $ 246,320 $ 208,588 $ 37,732 $ —

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2016
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): March 31, 2016 December 31, 2015 Computer equipment and software $ 237 $ 234 Laboratory equipment 3,157 3,041 Furniture and fixtures 552 552 Leasehold improvements 365 351 Construction in progress 565 — Total property and equipment 4,876 4,178 Less accumulated depreciation and amortization (1,311 ) (991 ) Property and equipment, net $ 3,565 $ 3,187

Accrued Expenses and Other Cu21

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2016
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): March 31, 2016 December 31, 2015 Employees’ compensation expenses $ 1,077 $ 2,047 Accrued professional services 1,523 1,177 Accrued preclinical costs $ 731 $ 642 Accrued clinical and process development costs — 101 Other 558 40 Total accrued expenses and other current liabilities $ 3,889 $ 4,007

Stock Option Plans (Tables)

Stock Option Plans (Tables)	3 Months Ended
	Mar. 31, 2016
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 March 31, 2016 2015 Research and development $ 2,228 $ 284 General and administrative 1,856 489 Total share-based compensation $ 4,084 $ 773
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, 2015 632 $ 13.07 Granted 880 $ 4.83 Vested and released (124 ) $ 7.20 Forfeited (148 ) $ 7.19 Outstanding at March 31, 2016 1,240 $ 7.45
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 March 31, 2016 2015 Option grants: Expected volatility 80 % 78 % Expected term (in years) 6.0 6.1 Expected dividend yield — — Risk-free interest rate 1.4 % 1.8 %
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 March 31, 2016 2015 Option grants: Expected volatility 89 % 80 % Expected term (in years) 3.3 7.7 Expected dividend yield — — Risk-free interest rate 1.1 % 1.7 %
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 PRICE (IN YEARS) (IN THOUSANDS) Balance at January 1, 2016 5,494 $ 8.75 7.8 $ 28,618 Options granted 386 $ 4.80 Options exercised (1,160 ) $ 0.42 Options cancelled (252 ) $ 23.39 Balance at March 31, 2016 4,468 $ 9.74 8.1 9,004 Vested and expected to vest as of March 31, 2016 4,419 $ 9.70 8.1 8,971 Exercisable as of March 31, 2016 1,969 $ 6.41 7.2 6,822 (a) The aggregate intrinsic value is calculated as the difference between the option exercise price and the closing price of common stock of $5.17 per share as of March 31, 2016.

Organization and Basis of Pre23

Organization and Basis of Presentation - Additional Information (Detail)	Jan. 29, 2016USD ($)shares	Mar. 31, 2015USD ($)shares	Jan. 31, 2015USD ($)shares	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)
Class of Stock [Line Items]
Date of incorporation				Jul. 17, 2006
Accumulated deficit | $				$ (99,560,000)		$ (84,168,000)
Issuance of common stock | shares		230,000	2,369,375
Net proceeds from issuance of common stock | $		$ 8,300,000	$ 130,600,000		$ 138,954,000
Over-Allotment Option [Member]
Class of Stock [Line Items]
Issuance of common stock | shares			359,918
Annapurna Therapeutics SAS [Member]
Class of Stock [Line Items]
Number of shares issued to acquired an entity | shares	13,100,000
Number of shares converted | shares	4,700,000
Common stock exchange ratio	9.5615
Termination fee lower | $	$ 4,000,000
Termination fee higher | $	$ 6,000,000

Cash Equivalents and Marketab24

Cash Equivalents and Marketable Securities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)Security
Cash And Cash Equivalents [Abstract]
Number of available-for-securities held | Security	0
Realized gains or losses on investments	$ 0
Contractual maturities of marketable securities	Less than one year
Proceeds from sales of available-for-sale securities	$ 0

Cash Equivalents and Marketab25

Cash Equivalents and Marketable Securities - Summary of Cash Equivalents and Marketable Securities (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	$ 37,738
Unrealized Loses	(6)
Estimated Fair Value	37,732
Less: Cash Equivalents, Amortized Cost Basis	(208,588)
Less: Cash Equivalents, Unrealized Gains	0
Less: Cash Equivalents, Unrealized Loses	0
Less: Cash Equivalents, Estimated Fair Value	(208,588)
Cash Equivalents And Marketable Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	246,326
Unrealized Loses	(6)
Estimated Fair Value	246,320
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	208,588
Estimated Fair Value	208,588
Certificates of Deposit [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	1,680
Estimated Fair Value	1,680
U.S. Treasury Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	15,046
Unrealized Loses	(4)
Estimated Fair Value	15,042
US Government Agency Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost Basis	21,012
Unrealized Loses	(2)
Estimated Fair Value	$ 21,010

Fair Value Measurements and F26

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities transferred within Level 3	$ 0	$ 0
Total assets	241,663,000	246,320,000
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 F27

Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets Measured and Recognized at Fair Value on Recurring Basis (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Assets:
Total assets	$ 241,663,000	$ 246,320,000
Money Market Funds - Cash Equivalent [Member]
Assets:
Total assets	241,663,000	208,588,000
Certificates of Deposit [Member]
Assets:
Total assets		1,680,000
U.S. Treasury Securities [Member]
Assets:
Total assets		15,042,000
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Total assets	241,663,000	208,588,000
Quoted Prices in Active Markets (Level 1) [Member] | Money Market Funds - Cash Equivalent [Member]
Assets:
Total assets	241,663,000	208,588,000
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets		37,732,000
Significant Other Observable Inputs (Level 2) [Member] | Certificates of Deposit [Member]
Assets:
Total assets		1,680,000
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Securities [Member]
Assets:
Total assets		15,042,000
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total assets	$ 0	0
U.S. Government Agency Securities [Member]
Assets:
Total assets		21,010,000
U.S. Government Agency Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets		$ 21,010,000

Significant Agreements - Additi

Significant Agreements - Additional Information (Detail) - University of California [Member] - USD ($)	1 Months Ended	3 Months Ended
	May. 31, 2010	Mar. 31, 2016
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	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 4,876	$ 4,178
Less accumulated depreciation and amortization	(1,311)	(991)
Property and equipment, net	3,565	3,187
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	237	234
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	3,157	3,041
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	552	552
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	365	$ 351
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 565

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 320	$ 118

Accrued Expenses and Other Cu31

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accrued Expenses And Other Current Liabilities [Abstract]
Employees’ compensation expenses	$ 1,077	$ 2,047
Accrued professional services	1,523	1,177
Accrued preclinical costs	731	642
Accrued clinical and process development costs		101
Other	558	40
Total accrued expenses and other current liabilities	$ 3,889	$ 4,007

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Jul. 31, 2015Claim	Mar. 31, 2016USD ($)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

Stock Option Plans - Additional

Stock Option Plans - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)Employee$ / sharesshares	Mar. 31, 2015USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair values of options granted | $ / shares	$ 3.29	$ 34
Total intrinsic value of options exercised	$ 6	$ 4.4
Number of employees affected by modifications of stock-based compensation awards | Employee	2
Unrecognized stock-based compensation, weighted-average period	3 years
Unrecognized stock-based compensation expense related to employees' awards	$ 21
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU granted | shares	880,000
Total fair values of RSUs vested	$ 1.1
Unrecognized compensation cost	$ 6.9
Unrecognized stock-based compensation, weighted-average period	2 years 8 months 12 days
Restricted Stock Units [Member] | Prior to April 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU granted | shares	0
Non Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation, weighted-average period	10 months 24 days
Unrecognized stock-based compensation expense related to employees' awards	$ 0.6
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
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
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense for modifications	$ 1.4
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense for modifications	$ 0.8
2014 Equity Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares authorized for issuance | shares	9,488,716
Shares available for future grants | shares	2,306,155
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued | shares	0	0
Common stock shares available for future grant | shares	675,383

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	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
NUMBER OF SHARES, Beginning Balance	5,494,000
NUMBER OF SHARES, Options granted	386,000
NUMBER OF SHARES, Options exercised	(1,160,000)
NUMBER OF SHARES, Options cancelled	(252,000)
NUMBER OF SHARES, Ending Balance	4,468,000	5,494,000
NUMBER OF SHARES, Vested and expected to vest	4,419,000
NUMBER OF SHARES, Exercisable	1,969,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
WEIGHTED-AVERAGE EXERCISE PRICE, Beginning Balance	$ 8.75
WEIGHTED-AVERAGE EXERCISE PRICE, Options granted	4.80
WEIGHTED-AVERAGE EXERCISE PRICE, Options exercised	0.42
WEIGHTED-AVERAGE EXERCISE PRICE, Options cancelled	23.39
WEIGHTED-AVERAGE EXERCISE PRICE, Ending Balance	9.74	$ 8.75
WEIGHTED-AVERAGE EXERCISE PRICE, Vested and expected to vest	9.70
WEIGHTED-AVERAGE EXERCISE PRICE, Exercisable	$ 6.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS)	8 years 1 month 6 days	7 years 9 months 18 days
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS), Vested and expected to vest	8 years 1 month 6 days
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (IN YEARS), Exercisable	7 years 2 months 12 days
AGGREGATE INTRINSIC VALUE, Options outstanding	$ 9,004	$ 28,618
AGGREGATE INTRINSIC VALUE, Vested and expected to vest	8,971
AGGREGATE INTRINSIC VALUE, Exercisable	$ 6,822

Stock Option Plans - Summary 35

Stock Option Plans - Summary of Stock Options Activity (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2016$ / shares
Equity [Abstract]
Aggregate intrinsic value of option per share	$ 5.17

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
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 4,084	$ 773
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	2,228	284
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 1,856	$ 489

Stock Option Plans - Summary 37

Stock Option Plans - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units [Member]	3 Months Ended
	Mar. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Beginning Balance | shares	632,000
Number of Shares, Granted | shares	880,000
Number of Shares, Vested and released | shares	(124,000)
Number of Shares, Forfeited | shares	(148,000)
Number of Shares, Ending Balance | shares	1,240,000
Weighted-Average Grant-Date Fair Value, Beginning Balance | $ / shares	$ 13.07
Weighted-Average Grant-Date Fair Value, Granted | $ / shares	4.83
Weighted-Average Grant-Date Fair Value, Vested and released | $ / shares	7.20
Weighted-Average Grant-Date Fair Value, Forfeited | $ / shares	7.19
Weighted-Average Grant-Date Fair Value, Ending Balance | $ / shares	$ 7.45

Stock Option Plans - Schedule o

Stock Option Plans - Schedule of Employees Stock Purchase Plan Valuation Assumptions (Detail)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	80.00%	78.00%
Expected term (in years)	6 years	6 years 1 month 6 days
Risk-free interest rate	1.40%	1.80%
Non Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	89.00%	80.00%
Expected term (in years)	3 years 3 months 18 days	7 years 8 months 12 days
Risk-free interest rate	1.10%	1.70%

401(k) Savings Plan - Additiona

401(k) Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Compensation And Retirement Disclosure [Abstract]
Contribution by company	$ 0.3	$ 0.1

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	5.7	5