Regulus Therapeutics (RGLS) 10-Q 2 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 28, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	RGLS
Entity Registrant Name	REGULUS THERAPEUTICS INC.
Entity Central Index Key	1,505,512
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		52,923,305

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 14,706	$ 15,960
Short-term investments	76,877	98,103
Restricted cash	80	1,256
Prepaid expenses	10,614	8,159
Contract and other receivables	286	10,021
Other current assets	267	759
Total current assets	102,830	134,258
Property and equipment, net	12,042	5,400
Intangibles, net	1,051	1,081
Other assets	343	344
Total assets	116,266	141,083
Current liabilities:
Accounts payable	5,724	2,717
Accrued liabilities	5,066	6,329
Accrued compensation	2,290	2,392
Current portion of deferred revenue	72	1,194
Total current liabilities	13,152	12,632
Term loan, less debt issuance costs	19,787	0
Deferred revenue, less current portion	2,011	2,065
Other long-term liabilities	8,631	2,308
Total liabilities	43,581	17,005
Commitments and Contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 52,923,305 and 52,669,266 shares issued and outstanding at September 30, 2016 (unaudited) and December 31, 2015, respectively	53	53
Additional paid-in capital	326,076	315,673
Accumulated other comprehensive loss	(113)	(133)
Accumulated deficit	(253,331)	(191,515)
Total stockholders’ equity	72,685	124,078
Total liabilities and stockholders’ equity	$ 116,266	$ 141,083

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	52,923,305	52,669,266
Common stock, shares outstanding	52,923,305	52,669,266

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues:
Total revenues	$ 204	$ 1,865	$ 1,176	$ 9,899
Operating expenses:
Research and development	14,554	10,965	49,326	43,593
General and administrative	4,842	4,245	13,609	13,703
Total operating expenses	19,396	15,210	62,935	57,296
Loss from operations	(19,192)	(13,345)	(61,759)	(47,397)
Other income (expense):
Interest and other income	237	335	608	686
Interest and other expense	(560)	(6)	(674)	(22)
Loss from valuation of convertible note payable	0	0	0	(1,811)
Loss before income taxes	(19,515)	(13,016)	(61,825)	(48,544)
Income tax (expense) benefit	(4)	16	9	22
Net loss	(19,519)	(13,000)	(61,816)	(48,522)
Other comprehensive loss:
Unrealized (loss) gain on short-term investments, net	(30)	40	20	96
Comprehensive loss	$ (19,549)	$ (12,960)	$ (61,796)	$ (48,426)
Net loss per share, basic and diluted (in dollars per share)	$ (0.37)	$ (0.25)	$ (1.17)	$ (0.95)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	52,835,414	51,990,460	52,776,459	51,052,068
Strategic Alliances and Collaborations
Revenues:
Total revenues	$ 204	$ 1,865	$ 1,176	$ 9,899

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net loss	$ (61,816)	$ (48,522)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	1,589	1,177
Loss from valuation of convertible note payable	0	1,811
Stock-based compensation	9,453	11,607
Amortization of premium on investments, net	525	1,130
Other	338	73
Change in operating assets and liabilities:
Contracts and other receivables	9,735	(50)
Prepaid expenses	(2,455)	(116)
Other assets	492	25
Accounts payable	3,007	1,024
Accrued liabilities	(1,187)	1,649
Accrued compensation	(102)	(109)
Deferred revenue	(1,176)	(2,257)
Deferred rent and other liabilities	(178)	(257)
Net cash used in operating activities	(41,775)	(32,815)
Investing activities
Purchases of short-term investments	(60,716)	(67,064)
Sales and maturities of short-term investments	81,437	76,411
Purchases of property and equipment	(746)	(873)
Acquisition of intangibles	(48)	(40)
Net cash provided by investing activities	19,927	8,434
Financing activities
Proceeds from borrowing under term loan, net	19,768	0
Proceeds from issuance of common stock, net	641	492
Proceeds from exercise of common stock options	309	5,001
Principal payments on other long-term obligations	(124)	(115)
Net cash provided by financing activities	20,594	5,378
Net decrease in cash and cash equivalents	(1,254)	(19,003)
Cash and cash equivalents at beginning of period	15,960	37,327
Cash and cash equivalents at end of period	14,706	18,324
Supplemental disclosure of cash flow information
Net changes in restricted cash	(1,176)	1,400
Interest paid	(518)	(22)
Income taxes paid	(1)	(1)
Supplemental disclosure of non-cash investing and financing activities
Allowance for tenant improvements	6,653	0
Amounts accrued for property and equipment	14	179
Amounts accrued for patent expenditures	$ 5	$ 0

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2015 , from which the balance sheet information herein was derived. Use of Estimates Our condensed financial statements are prepared in accordance with GAAP, which requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our financial statements and accompanying notes. An estimated loss contingency is accrued in our financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ from these estimates and assumptions. Revenue Recognition Our revenues generally consist of upfront payments for licenses or options to obtain licenses in the future, milestone payments and payments for other research services under strategic alliance and collaboration agreements. We recognize revenues when all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectability is reasonably assured. Multiple element arrangements, such as our strategic alliance agreements with Sanofi and AstraZeneca AB (“AstraZeneca”), are analyzed to determine whether the deliverables within the agreement can be separated or whether they must be accounted for as a single unit of accounting. Deliverables under the agreement will be accounted for as separate units of accounting provided that (i) a delivered item has value to the customer on a stand-alone basis; and (ii) if the agreement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the control of the vendor. The allocation of consideration amongst the deliverables under the agreement is derived using a “best estimate of selling price” if vendor specific objective evidence and third-party evidence of fair value is not available. If the delivered element does not have stand-alone value, the arrangement is then accounted for as a single unit of accounting, and we recognize the consideration received under the arrangement as revenue on a straight-line basis, which approximates effort over our estimated period of performance, which for us is typically the expected term of the research and development plan. Milestones We apply the milestone method of accounting to recognize revenue from milestone payments when earned, as evidenced by written acknowledgment from the collaborator or other persuasive evidence that the milestone has been achieved and the payment is non-refundable, provided that the milestone event is substantive. A milestone event is defined as an event (i) that can only be achieved based in whole or in part on either our performance or on the occurrence of a specific outcome resulting from our performance; (ii) for which there is substantive uncertainty at the inception of the arrangement that the event will be achieved; and (iii) that would result in additional payments being due to us. Events for which the occurrence is either contingent solely upon the passage of time or the result of a counterparty’s performance are not considered to be milestone events. A milestone event is substantive if all of the following conditions are met: (i) the consideration is commensurate with either our performance to achieve the milestone, or the enhancement of the value to the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone; (ii) the consideration relates solely to past performance; and (iii) the consideration is reasonable relative to all the deliverables and payment terms (including other potential milestone consideration) within the arrangement. We assess whether a milestone is substantive at the inception of each arrangement. If a milestone is deemed non-substantive, we will account for that milestone payment using a method consistent with the related units of accounting for the arrangement over the estimated performance period. Deferred Revenue Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets. Amounts not expected to be recognized within the next 12 months are classified as non-current deferred revenue. Stock-Based Compensation We account for stock-based compensation expense related to stock options granted to employees and members of our board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes option pricing model. We recognize stock-based compensation expense using the accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), we recognize compensation expense over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition over the vesting period. For performance-based awards granted to employees (i) the fair value of the award is determined on the grant date, (ii) we assess the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. We account for stock options granted to non-employees using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms. Fair Value Option Applicable accounting policies permit entities to choose, at specified election dates, to measure specified items at fair value if the decision about the election is: (1) applied instrument by instrument, (2) irrevocable, and (3) applied to an entire instrument. The balance of our convertible note payable, which was valued under the fair value option, was converted into shares of common stock in January 2015 (see Note 4). Clinical Trial and Preclinical Study Accruals We make estimates of our accrued expenses for clinical trial and preclinical study activities as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. These accruals are based upon estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites, clinical research organizations (“CROs”) and for other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If possible, we obtain information regarding unbilled services directly from these service providers. However, we may be required to estimate these services based on other information available to us. If we underestimate or overestimate the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, our estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in our accruals. Restricted Cash Restricted cash consists of amounts received for a specific and limited purpose, and therefore not available for general operating activities. In August 2015, we received $1.4 million in connection with our facility lease agreement with Walton Torrey Owner B, L.L.C, entered into in July 2015. The use of these funds are restricted to costs associated with the relocation of our corporate headquarters. As of September 30, 2016 , our restricted cash balance was $0.1 million . Prepaid Materials We capitalize the purchase of certain raw materials and related supplies for use in the manufacturing of drug product in our clinical development programs, as we have determined that these materials have alternative future use. We can use these raw materials and related supplies in multiple clinical drug products, and therefore have future use independent of the development status of any particular drug program until it is utilized in the manufacturing process. We periodically review these capitalized materials for indicators of impairment, including shelf life, continued alternative future use and obsolescence. We have not recorded any adjustments to the carrying value of these materials to date. As of September 30, 2016 and December 31, 2015 , our prepaid materials balance was $6.9 million and $5.5 million , respectively, which amounts are included in prepaid expenses in our consolidated balance sheets. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2014-09, Revenue from Contracts with Customers . Adoption of ASU No. 2014-09 requires that an entity recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein and requires expanded disclosures. We are currently evaluating the impact of adoption on our financial statements. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern , which requires management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. This standard is effective for annual reporting periods ending after December 15, 2016 and interim periods thereafter. Early application is permitted. The adoption of this guidance will have no impact on our financial statements. In April 2015, the FASB issued ASU No. 2015-03, Interest- Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs were not affected by the amendments in ASU No. 2015-03. In June 2016, upon entering into a loan and security agreement, we adopted ASU No. 2015-03, which resulted in the classification of $0.2 million of debt issuance costs against the principal balance of our outstanding term loan of $20.0 million . In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which eliminates the requirement for public companies to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. Additionally, the standard requires public companies to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. Furthermore, the standard requires presentation of financial assets and liabilities by measurement category and form of financial asset on the balance sheet or accompanying notes to the financial statements. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases, which increases transparency and comparability among organizations by requiring recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting, which is intended to simplify several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The standard is effective for annual reporting periods beginning after December 15, 2016, and interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , which addresses the presentation and classification of certain cash receipts and cash payments in the statement of cash flows under Accounting Standards Codification 230. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those fiscal years. Early application is permitted. The adoption of this guidance will have no impact on our financial statements.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of options outstanding under our stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive consisted of 3,131,911 and 3,762,952 shares attributable to common stock options for the three and nine months ended September 30, 2016 , respectively, compared to 2,269,605 and 2,499,389 shares attributable to common stock options for the same periods in 2015 .

Investments

Investments	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Investments	Investments We invest our excess cash in commercial paper and debt instruments of financial institutions and corporations. As of September 30, 2016 , our short-term investments had a weighted average maturity of less than two years. The following tables summarize our short-term investments (in thousands): Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of September 30, 2016 Corporate debt securities 2 or less $ 66,294 $ 14 $ (63 ) $ 66,245 Certificates of deposit 2 or less 7,640 — — 7,640 Commercial paper 1 or less 2,993 — (1 ) 2,992 Total $ 76,927 $ 14 $ (64 ) $ 76,877 Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of December 31, 2015 Corporate debt securities 2 or less $ 81,054 $ 16 $ (103 ) $ 80,967 Certificates of deposit 2 or less 13,640 — — 13,640 Commercial paper 1 or less 3,490 6 — 3,496 Total $ 98,184 $ 22 $ (103 ) $ 98,103

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We have certain financial assets recorded at fair value which have been classified as Level 1, 2, or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants as of the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The accounting standards provide an established hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs that market participants would use in valuing the asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our assumptions about the factors that market participants would use in valuing the asset or liability. The accounting standards prioritize the inputs used in measuring the fair value into the following hierarchy: • Level 1 includes financial instruments for which quoted market prices for identical instruments are available in active markets. • Level 2 includes financial instruments for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. • Level 3 includes financial instruments for which fair value is derived from valuation techniques in which one or more significant inputs are unobservable, including management’s own assumptions. Financial Assets Measured at Fair Value The following table presents our fair value hierarchy for assets measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 (in thousands): Fair value as of September 30, 2016 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 12,802 $ 12,802 $ — $ — Corporate debt securities 66,245 — 66,245 — Certificates of deposit 7,640 — 7,640 — Commercial paper 2,992 — 2,992 — $ 89,679 $ 12,802 $ 76,877 $ — Fair value as of December 31, 2015 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 15,152 $ 15,152 $ — $ — Corporate debt securities 80,967 — 80,967 — Certificates of deposit 13,640 — 13,640 — Commercial paper 3,496 — 3,496 — $ 113,255 $ 15,152 $ 98,103 $ — We obtain pricing information from quoted market prices or quotes from brokers/dealers. We generally determine the fair value of our investment securities using standard observable inputs, including reported trades, broker/dealer quotes, bids and/or offers. Refer to Note 3 for information regarding our investments. Financial Liabilities Measured at Fair Value In October 2012, in conjunction with our initial public offering, an amended and restated convertible promissory note originally issued to Glaxo Group Limited in February 2010 rolled over into a new promissory note (the "Post-IPO GSK Note"). The Post-IPO GSK Note was established in the principal amount of $5.4 million , with a maturity date of October 9, 2015 . We used an income approach in the form of a convertible bond valuation model to value our convertible note payable. The convertible bond model considered the debt and option characteristics of the note. On January 29, 2015, the principal amount outstanding under the Post-IPO GSK Note of $5.4 million was converted into 1,356,738 shares of our common stock at a conversion price of $4.00 per share. A final valuation upon conversion was performed, considering only the option characteristics of the note as its conversion was certain. Key inputs of volatility, risk-free rate and credit spread were considered, however, the final valuation was substantially driven by the number of shares of common stock issued upon conversion ( 1,356,738 ) and our stock price on the date of conversion ( $18.58 ). Upon issuance of the common stock, the fair value of the convertible note was classified into stockholders' equity. We recorded a loss from the change in valuation of the convertible note payable of $1.8 million in the condensed statements of operations and comprehensive loss upon conversion in January 2015.

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Term Loan	Term Loan On June 17, 2016, we entered into a loan and security agreement ("Loan Agreement") with Oxford Finance, LLC, ("Oxford"), pursuant to which Oxford agreed to lend us up to $30.0 million , issuable in two separate term loans of $20.0 million (the "Term A Loan") and $10.0 million (the "Term B Loan"). We collectively refer to the Term A Loan and the Term B Loan as Term Loans. On June 22, 2016, we received $20.0 million in proceeds from the Term A Loan, net of debt issuance costs. Under the terms of the Loan Agreement we may, at our sole discretion, borrow $10.0 million under the Term B Loan following the achievement of a defined milestone event until the earlier of 60 days thereafter or March 31, 2017. All outstanding Term Loans will mature on June 1, 2020 (the “Maturity Date”) and we will have interest-only payments through June 1, 2018, followed by 24 equal monthly payments of principal and unpaid accrued interest. The Term Loans will bear interest at a floating per annum rate equal to (i) 8.51% plus (ii) the greater of (a) the 30 day U.S. Dollar LIBOR rate reported in The Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue and (b) 0.44% . We have the option to prepay all, but not less than all, of the borrowed amounts, provided that we will be obligated to pay a prepayment fee equal to (i) 2% of the outstanding principal balance of the applicable Term Loan if prepayment is made prior to the second anniversary of the applicable funding date of the Term Loan, provided no prepayment fee will be due in connection with a prepayment made on or prior to the first anniversary of the applicable funding date of the Term Loan in connection with an acquisition of our company, or (ii) 1% of the applicable Term Loan prepaid thereafter and prior to the Maturity Date. We will be required to make a final payment of 5.5% of the principal balance outstanding, payable on the earlier of (i) the Maturity Date, (ii) acceleration of any Term Loan, or (iii) the prepayment of the Term Loans. We may use the proceeds from the Term Loans solely for working capital and to fund our general business requirements. Our obligations under the Loan Agreement are secured by a first priority security interest in substantially all of our current and future assets, other than our intellectual property. We have also agreed not to encumber our intellectual property assets, except as permitted by the Loan Agreement. As of September 30, 2016 , we had $20.0 million outstanding under the Term A Loan. The Term A Loan was recorded at its initial carrying value of $20.0 million , less debt issuance costs of approximately $0.2 million . In connection with the Term A Loan, the debt issuance costs have been recorded as a debt discount in our consolidated balance sheets, which are being recorded as interest expense over the life of the Term A Loan using an effective interest rate of 8.98% . The exit fee is being accrued over the life of the Term A Loan through interest expense. As of September 30, 2016 , we were in compliance with all material covenants under the Loan Agreement. Future principal payments for the Term A Loan due under the Loan Agreement are as follows (in thousands): 2016 $ — 2017 — 2018 5,000 2019 10,000 2020 5,000 $ 20,000

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Stockholders’ Equity Shares Reserved for Future Issuance The following shares of common stock were reserved for future issuance as of September 30, 2016 : Common stock options outstanding 6,621,106 Common stock available for future grant under 2012 Equity Incentive Plan 2,448,385 Common stock available for future grant under 2015 Inducement Plan 581,806 Employee Stock Purchase Plan 1,594,452 Total common shares reserved for future issuance 11,245,749 The following table summarizes our stock option activity under all equity incentive plans for the nine months ended September 30, 2016 (shares in thousands): Number of options Weighted average exercise price Options outstanding at December 31, 2015 5,126 $ 8.91 Granted 2,414 $ 6.57 Exercised (88 ) $ 3.50 Canceled/forfeited/expired (831 ) $ 10.41 Options outstanding at September 30, 2016 6,621 $ 7.94 Stock-Based Compensation The following table summarizes the weighted average assumptions used to estimate the fair value of stock options and performance stock awards granted to employees under our 2012 Equity Incentive Plan and 2015 Inducement Plan and the shares purchasable under our Employee Stock Purchase Plan during the periods presented: Three months ended Nine months ended 2016 2015 2016 2015 Stock options Risk-free interest rate 1.5 % 1.7 % 1.4 % 1.8 % Volatility 80.0 % 78.9 % 79.9 % 78.8 % Dividend yield — — — — Expected term (years) 5.7 6.1 5.9 6.1 Performance stock options Risk-free interest rate — 1.6 % 1.4 % 1.8 % Volatility — 79.3 % 79.3 % 76.7 % Dividend yield — — — — Expected term (years) 0.0 6.1 6.0 6.0 Employee stock purchase plan shares Risk-free interest rate 0.5 % 0.2 % 0.5 % 0.1 % Volatility 94.5 % 77.1 % 85.4 % 75.6 % Dividend yield — — — — Expected term (years) 0.5 0.5 0.5 0.5 The following table summarizes the allocation of our stock-based compensation expense for all stock awards during the periods presented (in thousands): Three months ended Nine months ended 2016 2015 2016 2015 Research and development $ 1,199 $ 1,048 $ 3,931 $ 6,500 General and administrative 2,268 1,586 5,522 5,107 Total $ 3,467 $ 2,634 $ 9,453 $ 11,607

Strategic Alliances and Collabo

Strategic Alliances and Collaborations	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Strategic Alliances and Collaborations	Strategic Alliances and Collaborations The following table summarizes our total revenues from our strategic alliances and collaborations during the periods presented (in thousands): Three months ended Nine months ended 2016 2015 2016 2015 AstraZeneca $ 186 $ 1,380 $ 1,122 $ 8,028 Sanofi 18 18 54 54 Biogen — 467 — 1,817 Total $ 204 $ 1,865 $ 1,176 $ 9,899 AstraZeneca In August 2012, we entered into a collaboration and license agreement with AstraZeneca. Under the terms of the agreement, we agreed to collaborate with AstraZeneca to identify, research and develop compounds targeting three micro RNA alliance targets primarily in the fields of cardiovascular diseases, metabolic diseases and oncology. Pursuant to the agreement, we granted AstraZeneca an exclusive, worldwide license to develop, manufacture and commercialize lead compounds designated by AstraZeneca in the course of the collaboration activities against the alliance targets for all human therapeutic uses. Under the terms of the agreement we were required to use commercially reasonable efforts to perform all research, development and manufacturing activities described in the research plan, at our cost, until the acceptance of an investigational new drug application ("IND") or the end of the research term, which ended in August 2016. Under the terms of the agreement, we received an upfront payment of $3.0 million in October 2012. We determined the elements within the agreement should be treated as a single unit of accounting because the delivered element, the license, did not have stand-alone value. As a result, we recognized revenue related to the upfront payment on a straight-line basis over the period of performance, which was four years based on the term of the research and development plan and ended in August 2016. In connection with the collaboration and license agreement and concurrently with our initial public offering, we sold AstraZeneca 6,250,000 shares of our common stock in a private placement at a price per share of $4.00 . Under the terms of the Common Stock Purchase Agreement ("CSPA"), AstraZeneca could not sell, transfer, make any short sale of, or grant any option for the sale of any common stock for a 365 -day period following the effective date of our initial public offering. The CSPA and collaboration and license agreement were negotiated concurrently and were therefore evaluated as a single agreement. Based upon restricted stock studies of similar duration and a Black-Scholes valuation to measure a discount for lack of marketability, $4.3 million was attributed to the collaboration and license agreement. We recognized the $4.3 million into revenue ratably over the period of performance of the research and development plan under the collaboration over four years, which ended in August 2016. In March 2015, we earned a $2.5 million preclinical milestone payment upon AstraZeneca’s selection of RG-125, a GalNAc-conjugated anti-miR targeting micro RNA-103/107, as a lead compound under the agreement. In December 2015, we earned a $10.0 million clinical milestone payment upon AstraZeneca's first patient dosing in a first-in-human Phase I clinical study of RG-125. If RG-125 is successfully developed and commercialized through pre-agreed sales targets, we could receive additional milestone payments of up to $160.0 million , including up to $32.5 million for clinical milestones, and up to $127.5 million for commercialization milestones. In addition, we are entitled to receive royalties based on a percentage of net sales which will range from the mid to high single digits, depending upon the volume of sales, which royalties may be reduced in certain, limited circumstances. We evaluated the contingent event-based payments under our collaboration and license agreement with AstraZeneca and determined that the preclinical milestone and the milestone earned for the initiation of a Phase I clinical trial met the definition of substantive milestones. Accordingly, revenue for these achievements was recognized in its entirety in the period when the milestone was achieved and collectability was reasonably assured. Other contingent event-based payments under the agreement for which payment is contingent upon the results of AstraZeneca’s performance will not be accounted for using the milestone method. Such payments will be recognized as revenue over the remaining estimated period of performance, if any, and when collectability is reasonably assured. In January 2015, we entered into a letter agreement with AstraZeneca to amend the collaboration and license agreement. Under the terms of the letter agreement, we agreed to perform additional miR-103/107 program research and development activities related to RG-125. AstraZeneca agreed to fund 50% of the costs for these additional activities, as outlined in the letter agreement. In accordance with the collaboration and license agreement, AstraZeneca funded 100% of the costs for product manufacturing activities outlined in the letter agreement necessary to support a Phase I clinical study. In December 2015, we completed a technology transfer to AstraZeneca and have no further obligations to AstraZeneca for future development of RG-125. We recognized $0.9 million and $4.1 million for the three and nine months ended September 30, 2015 , respectively, for the performance of research and development and product manufacturing activities outlined in the letter agreement. As of December 31, 2015, our obligations under the letter agreement were complete. Sanofi In July 2012, we amended and restated our collaboration and license agreement with Sanofi to expand the potential therapeutic applications of the micro RNA alliance targets to be developed under such agreement. We determined that the elements within the strategic alliance agreement with Sanofi should be treated as a single unit of accounting because the delivered elements did not have stand-alone value to Sanofi. The following elements were delivered as part of the strategic alliance with Sanofi: (1) a license for up to four micro RNA targets; and (2) a research license under our technology alliance. In June 2013, the original research term expired, upon which we and Sanofi entered into an option agreement pursuant to which Sanofi was granted an exclusive right to negotiate the co-development and commercialization of certain of our unencumbered micro RNA programs and we were granted the exclusive right to negotiate with Sanofi for co-development and commercialization of certain miR-21 anti-miRs in oncology and Alport syndrome. In July 2013, we received an upfront payment of $2.5 million , of which $1.25 million is creditable against future amounts payable by Sanofi to us under any future co-development and commercialization agreement we enter pursuant to the option agreement. Revenue associated with the creditable portion of this option payment remained deferred as of September 30, 2016 , and will remain deferred until its application to a creditable transaction. The non-creditable portion of this payment, $1.25 million , was recognized as revenue over the option period from the effective date of the option agreement in June 2013 through the expiration of the option period in January 2014. In February 2014, we and Sanofi entered into a second amended and restated collaboration and license agreement (the “2014 Sanofi Amendment”) to renew our strategic alliance to discover, develop and commercialize micro RNA therapeutics to focus on specific orphan disease and oncology targets. Under the terms of our renewed alliance, Sanofi will have opt-in rights to our clinical fibrosis program targeting miR-21 for the treatment of Alport syndrome, our preclinical program targeting miR-21 for oncology indications, and our preclinical program targeting miR-221/222 for hepatocellular carcinoma (“HCC”). We are responsible for developing each of these programs to proof-of-concept, at which time Sanofi has an exclusive option on each program. If Sanofi chooses to exercise its option on any of these programs, Sanofi will reimburse us for a significant portion of our preclinical and clinical development costs and will also pay us an option exercise fee for any such program, provided that $1.25 million of the $2.5 million upfront option fee paid to us by Sanofi in connection with the June 2013 option agreement will be creditable against such option exercise fee. We are eligible to receive royalties on micro RNA therapeutic products commercialized by Sanofi and will have the right to co-promote these products. In connection with the 2014 Sanofi Amendment, we entered into a Common Stock Purchase Agreement (the “Purchase Agreement”), pursuant to which we sold 1,303,780 shares of our common stock to Aventisub LLC (formerly Aventis Holdings, Inc.) (“Aventis”), an entity affiliated with Sanofi, in a private placement at a price per share of $7.67 for an aggregate purchase price of $10.0 million . Under the terms of the Purchase Agreement, Aventis was not permitted to sell, transfer, make any short sale of, or grant any option for the sale of any common stock for the 12 -month period following its effective date. The Purchase Agreement and the 2014 Sanofi Amendment were negotiated concurrently and were therefore evaluated as a single agreement. Based upon restricted stock studies of similar duration and a Black-Scholes valuation to measure the discount for lack of marketability, approximately $0.4 million of the proceeds from the Purchase Agreement was attributed to the 2014 Sanofi Amendment, and represents consideration for the value of the program targeting miR-221/222 for HCC. As this element does not have stand-alone value, we are recognizing the $0.4 million allocated consideration into revenue ratably over the estimated period of performance of the miR-221/222 program. As of September 30, 2016 , deferred revenue associated with the Purchase Agreement and the 2014 Sanofi Amendment was $0.2 million , which we are expecting to recognize over the remaining estimated period of performance of approximately four years. We are eligible to receive milestone payments of up to $101.8 million for proof-of-concept option exercise fees (net of $1.25 million creditable, as noted above), $15.0 million for clinical milestones and up to $300.0 million for regulatory and commercial milestones. In addition, we are entitled to receive royalties based on a percentage of net sales of any products from the miR-21 and miR-221/222 programs which, in the case of sales in the United States, will be in the middle of the 10 to 20% range, and, in the case of sales outside of the United States, will range from the low end to the middle of the 10 to 20% range, depending upon the volume of sales. If we exercise our option to co-promote a product, we will continue to be eligible to receive royalties on net sales of each product in the United States at the same rate, unless we elect to share a portion of Sanofi’s profits from sales of such product in the United States in lieu of royalties. We have evaluated the contingent event-based payments under the 2014 Sanofi Amendment and determined that the milestone payments meet the definition of substantive milestones. Accordingly, revenue for these achievements will be recognized in their entirety in the period when the milestone is achieved and collectability is reasonably assured. Other contingent event-based payments under the 2014 Sanofi Amendment for which payment is contingent upon the results of Sanofi’s performance will not be accounted for using the milestone method. Such payments will be recognized as revenue over the remaining estimated period of performance, if any, and when collectability is reasonably assured. Biogen In August 2014, we entered into a collaboration and license agreement with Biogen to collaborate on micro RNA biomarkers for multiple sclerosis. Pursuant to the terms of the collaboration and license agreement, we received an upfront payment of $2.0 million , which was treated as a single unit of accounting as the license did not have stand-alone value. The $2.0 million up-front payment was recognized on a straight line basis over the estimated period of performance of approximately one year , ending September 2015. In July 2015, the collaboration and license agreement was amended to modify the conditions of the third research-based milestone. Additionally, the amendment extended the expected research term from 12 months to 14 months . We recognized the remaining upfront payment on a straight-line basis over the amended expected term. As of December 31, 2015, our period of performance was complete and the deferred revenue balance was zero . In January 2015, May 2015, and September 2015, we earned research milestone payments under the collaboration and license agreement of $0.1 million , $0.3 million and $0.3 million , respectively. These milestone payments met the definition of substantive milestones, and accordingly, revenue for these achievements was recognized in the period the milestones were achieved and collectability was reasonably assured.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions We have entered into certain agreements with related parties in the ordinary course of business to license intellectual property and to procure administrative and research and development support services. In September 2014, we entered into an agreement with Sanofi-Aventis Deutschland GmbH (“Sanofi Deutschland”), a contract manufacturing subsidiary of Sanofi, for the manufacture of certain drug substance requirements and other services to support our preclinical and clinical activities associated with the RG-012 program. Pursuant to this agreement, we may engage Sanofi Deutschland from time-to-time to manufacture RG-012 drug product on our behalf. Expenses incurred under the Sanofi agreement for services performed or out-of-pocket expenses were $0.2 million and $1.0 million for the three and nine months ended September 30, 2016 , respectively, compared to zero and $0.4 million for the same periods in 2015 . In February 2015, we entered into a letter agreement with Alnylam Pharmaceuticals, Inc. ("Alnylam") pursuant to which we and Alnylam agreed to the financial terms for certain technology acquired by Alnylam within the licensed patent rights under our Amended and Restated License and Collaboration Agreement (the “Additional Patent Rights”) with Alnylam and Ionis Pharmaceuticals, Inc. In addition to any royalties payable by us to Alnylam pursuant to the terms of the Amended and Restated License and Collaboration Agreement, we agreed to pay Alnylam an additional low single-digit royalty on net sales of certain products utilizing the Additional Patent Rights, with the exact royalty percentage payable being dependent on the total amount of net sales during the calendar year. We also agreed to pay Alnylam milestone payments on certain products utilizing the additional patent rights of up to $33.0 million per product upon the achievement of certain regulatory milestone events. There was no activity under this agreement for the three or nine months ended September 30, 2016 .

Basis of Presentation and Sum14

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2015 , from which the balance sheet information herein was derived.
Use of Estimates	Use of Estimates Our condensed financial statements are prepared in accordance with GAAP, which requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our financial statements and accompanying notes. An estimated loss contingency is accrued in our financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ from these estimates and assumptions.
Revenue Recognition	Revenue Recognition Our revenues generally consist of upfront payments for licenses or options to obtain licenses in the future, milestone payments and payments for other research services under strategic alliance and collaboration agreements. We recognize revenues when all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectability is reasonably assured. Multiple element arrangements, such as our strategic alliance agreements with Sanofi and AstraZeneca AB (“AstraZeneca”), are analyzed to determine whether the deliverables within the agreement can be separated or whether they must be accounted for as a single unit of accounting. Deliverables under the agreement will be accounted for as separate units of accounting provided that (i) a delivered item has value to the customer on a stand-alone basis; and (ii) if the agreement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the control of the vendor. The allocation of consideration amongst the deliverables under the agreement is derived using a “best estimate of selling price” if vendor specific objective evidence and third-party evidence of fair value is not available. If the delivered element does not have stand-alone value, the arrangement is then accounted for as a single unit of accounting, and we recognize the consideration received under the arrangement as revenue on a straight-line basis, which approximates effort over our estimated period of performance, which for us is typically the expected term of the research and development plan. Milestones We apply the milestone method of accounting to recognize revenue from milestone payments when earned, as evidenced by written acknowledgment from the collaborator or other persuasive evidence that the milestone has been achieved and the payment is non-refundable, provided that the milestone event is substantive. A milestone event is defined as an event (i) that can only be achieved based in whole or in part on either our performance or on the occurrence of a specific outcome resulting from our performance; (ii) for which there is substantive uncertainty at the inception of the arrangement that the event will be achieved; and (iii) that would result in additional payments being due to us. Events for which the occurrence is either contingent solely upon the passage of time or the result of a counterparty’s performance are not considered to be milestone events. A milestone event is substantive if all of the following conditions are met: (i) the consideration is commensurate with either our performance to achieve the milestone, or the enhancement of the value to the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone; (ii) the consideration relates solely to past performance; and (iii) the consideration is reasonable relative to all the deliverables and payment terms (including other potential milestone consideration) within the arrangement. We assess whether a milestone is substantive at the inception of each arrangement. If a milestone is deemed non-substantive, we will account for that milestone payment using a method consistent with the related units of accounting for the arrangement over the estimated performance period. Deferred Revenue Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets. Amounts not expected to be recognized within the next 12 months are classified as non-current deferred revenue.
Stock-Based Compensation	Stock-Based Compensation We account for stock-based compensation expense related to stock options granted to employees and members of our board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes option pricing model. We recognize stock-based compensation expense using the accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), we recognize compensation expense over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition over the vesting period. For performance-based awards granted to employees (i) the fair value of the award is determined on the grant date, (ii) we assess the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. We account for stock options granted to non-employees using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms.
Fair Value Option	Fair Value Option Applicable accounting policies permit entities to choose, at specified election dates, to measure specified items at fair value if the decision about the election is: (1) applied instrument by instrument, (2) irrevocable, and (3) applied to an entire instrument. The balance of our convertible note payable, which was valued under the fair value option, was converted into shares of common stock in January 2015 (see Note 4). Fair Value Measurements We have certain financial assets recorded at fair value which have been classified as Level 1, 2, or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants as of the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The accounting standards provide an established hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs that market participants would use in valuing the asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our assumptions about the factors that market participants would use in valuing the asset or liability. The accounting standards prioritize the inputs used in measuring the fair value into the following hierarchy: • Level 1 includes financial instruments for which quoted market prices for identical instruments are available in active markets. • Level 2 includes financial instruments for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. • Level 3 includes financial instruments for which fair value is derived from valuation techniques in which one or more significant inputs are unobservable, including management’s own assumptions.
Clinical Trial and Preclinical Study Accruals	Clinical Trial and Preclinical Study Accruals We make estimates of our accrued expenses for clinical trial and preclinical study activities as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. These accruals are based upon estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites, clinical research organizations (“CROs”) and for other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If possible, we obtain information regarding unbilled services directly from these service providers. However, we may be required to estimate these services based on other information available to us. If we underestimate or overestimate the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, our estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in our accruals.
Restricted Cash	Restricted Cash Restricted cash consists of amounts received for a specific and limited purpose, and therefore not available for general operating activities.
Prepaid Expenses	Prepaid Materials We capitalize the purchase of certain raw materials and related supplies for use in the manufacturing of drug product in our clinical development programs, as we have determined that these materials have alternative future use. We can use these raw materials and related supplies in multiple clinical drug products, and therefore have future use independent of the development status of any particular drug program until it is utilized in the manufacturing process. We periodically review these capitalized materials for indicators of impairment, including shelf life, continued alternative future use and obsolescence. We have not recorded any adjustments to the carrying value of these materials to date.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2014-09, Revenue from Contracts with Customers . Adoption of ASU No. 2014-09 requires that an entity recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein and requires expanded disclosures. We are currently evaluating the impact of adoption on our financial statements. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern , which requires management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. This standard is effective for annual reporting periods ending after December 15, 2016 and interim periods thereafter. Early application is permitted. The adoption of this guidance will have no impact on our financial statements. In April 2015, the FASB issued ASU No. 2015-03, Interest- Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs were not affected by the amendments in ASU No. 2015-03. In June 2016, upon entering into a loan and security agreement, we adopted ASU No. 2015-03, which resulted in the classification of $0.2 million of debt issuance costs against the principal balance of our outstanding term loan of $20.0 million . In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which eliminates the requirement for public companies to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. Additionally, the standard requires public companies to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. Furthermore, the standard requires presentation of financial assets and liabilities by measurement category and form of financial asset on the balance sheet or accompanying notes to the financial statements. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases, which increases transparency and comparability among organizations by requiring recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting, which is intended to simplify several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The standard is effective for annual reporting periods beginning after December 15, 2016, and interim periods within those annual reporting periods. Early application is permitted. We are currently evaluating the impact of adoption on our financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , which addresses the presentation and classification of certain cash receipts and cash payments in the statement of cash flows under Accounting Standards Codification 230. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those fiscal years. Early application is permitted. The adoption of this guidance will have no impact on our financial statements.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Summary of Short-Term Investments	The following tables summarize our short-term investments (in thousands): Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of September 30, 2016 Corporate debt securities 2 or less $ 66,294 $ 14 $ (63 ) $ 66,245 Certificates of deposit 2 or less 7,640 — — 7,640 Commercial paper 1 or less 2,993 — (1 ) 2,992 Total $ 76,927 $ 14 $ (64 ) $ 76,877 Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of December 31, 2015 Corporate debt securities 2 or less $ 81,054 $ 16 $ (103 ) $ 80,967 Certificates of deposit 2 or less 13,640 — — 13,640 Commercial paper 1 or less 3,490 6 — 3,496 Total $ 98,184 $ 22 $ (103 ) $ 98,103

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents our fair value hierarchy for assets measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 (in thousands): Fair value as of September 30, 2016 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 12,802 $ 12,802 $ — $ — Corporate debt securities 66,245 — 66,245 — Certificates of deposit 7,640 — 7,640 — Commercial paper 2,992 — 2,992 — $ 89,679 $ 12,802 $ 76,877 $ — Fair value as of December 31, 2015 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 15,152 $ 15,152 $ — $ — Corporate debt securities 80,967 — 80,967 — Certificates of deposit 13,640 — 13,640 — Commercial paper 3,496 — 3,496 — $ 113,255 $ 15,152 $ 98,103 $ —

Term Loan (Tables)

Term Loan (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	Future principal payments for the Term A Loan due under the Loan Agreement are as follows (in thousands): 2016 $ — 2017 — 2018 5,000 2019 10,000 2020 5,000 $ 20,000

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Common Stock Reserved for Future Issuance	The following shares of common stock were reserved for future issuance as of September 30, 2016 : Common stock options outstanding 6,621,106 Common stock available for future grant under 2012 Equity Incentive Plan 2,448,385 Common stock available for future grant under 2015 Inducement Plan 581,806 Employee Stock Purchase Plan 1,594,452 Total common shares reserved for future issuance 11,245,749
Stock Option Activity	The following table summarizes our stock option activity under all equity incentive plans for the nine months ended September 30, 2016 (shares in thousands): Number of options Weighted average exercise price Options outstanding at December 31, 2015 5,126 $ 8.91 Granted 2,414 $ 6.57 Exercised (88 ) $ 3.50 Canceled/forfeited/expired (831 ) $ 10.41 Options outstanding at September 30, 2016 6,621 $ 7.94
Assumptions Used to Estimate Fair Value of Stock Options and Performance Stock and Employee Stock Purchase Plan	The following table summarizes the weighted average assumptions used to estimate the fair value of stock options and performance stock awards granted to employees under our 2012 Equity Incentive Plan and 2015 Inducement Plan and the shares purchasable under our Employee Stock Purchase Plan during the periods presented: Three months ended Nine months ended 2016 2015 2016 2015 Stock options Risk-free interest rate 1.5 % 1.7 % 1.4 % 1.8 % Volatility 80.0 % 78.9 % 79.9 % 78.8 % Dividend yield — — — — Expected term (years) 5.7 6.1 5.9 6.1 Performance stock options Risk-free interest rate — 1.6 % 1.4 % 1.8 % Volatility — 79.3 % 79.3 % 76.7 % Dividend yield — — — — Expected term (years) 0.0 6.1 6.0 6.0 Employee stock purchase plan shares Risk-free interest rate 0.5 % 0.2 % 0.5 % 0.1 % Volatility 94.5 % 77.1 % 85.4 % 75.6 % Dividend yield — — — — Expected term (years) 0.5 0.5 0.5 0.5
Stock-Based Compensation	The following table summarizes the allocation of our stock-based compensation expense for all stock awards during the periods presented (in thousands): Three months ended Nine months ended 2016 2015 2016 2015 Research and development $ 1,199 $ 1,048 $ 3,931 $ 6,500 General and administrative 2,268 1,586 5,522 5,107 Total $ 3,467 $ 2,634 $ 9,453 $ 11,607

Strategic Alliances and Colla19

Strategic Alliances and Collaborations (Tables)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue from Strategic Alliances	The following table summarizes our total revenues from our strategic alliances and collaborations during the periods presented (in thousands): Three months ended Nine months ended 2016 2015 2016 2015 AstraZeneca $ 186 $ 1,380 $ 1,122 $ 8,028 Sanofi 18 18 54 54 Biogen — 467 — 1,817 Total $ 204 $ 1,865 $ 1,176 $ 9,899

Basis of Presentation and Sum20

Basis of Presentation and Summary of Significant Accounting Policies (Detail) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Aug. 31, 2015	Oct. 31, 2012
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 80,000	$ 1,256,000	$ 1,400,000
Prepaid expenses	10,614,000	8,159,000
Debt instrument, face amount				$ 5,400,000
Debt Financing Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred finance cost	200,000
Debt instrument, face amount	20,000,000
Prepaid Materials
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses	$ 6,900,000	$ 5,500,000

Net Loss Per Share (Detail)

Net Loss Per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Potentially dilutive securities not included in calculation of diluted net loss per share (in shares)	3,131,911	2,269,605	3,762,952	2,499,389

Investments (Summary of Short-T

Investments (Summary of Short-Term Investments) (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Investment [Line Items]
Maturity weighted average period, in years (less than)	2 years
Amortized cost	$ 76,927	$ 98,184
Unrealized Gains	14	22
Unrealized Losses	(64)	(103)
Estimated fair value	$ 76,877	$ 98,103
Corporate debt securities
Investment [Line Items]
Maturity (or less) (in years)	2 years	2 years
Amortized cost	$ 66,294	$ 81,054
Unrealized Gains	14	16
Unrealized Losses	(63)	(103)
Estimated fair value	$ 66,245	$ 80,967
Certificates of deposit
Investment [Line Items]
Maturity (or less) (in years)	2 years	2 years
Amortized cost	$ 7,640	$ 13,640
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated fair value	$ 7,640	$ 13,640
Commercial paper
Investment [Line Items]
Maturity (or less) (in years)	1 year	1 year
Amortized cost	$ 2,993	$ 3,490
Unrealized Gains	0	6
Unrealized Losses	(1)	0
Estimated fair value	$ 2,992	$ 3,496

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 89,679	$ 113,255
Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	12,802	15,152
Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	66,245	80,967
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	7,640	13,640
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,992	3,496
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	12,802	15,152
Level 1 | Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	12,802	15,152
Level 1 | Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 1 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 1 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	76,877	98,103
Level 2 | Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 2 | Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	66,245	80,967
Level 2 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	7,640	13,640
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,992	3,496
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 3 | Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 3 | Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 3 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 3 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 0	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Detail) - USD ($)	Jan. 29, 2015	Jan. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Oct. 31, 2012
Fair Value Disclosures [Abstract]
Debt instrument, face amount							$ 5,400,000
Number of convertible note payable converted in to common stock (in shares)	1,356,738
Conversion price per share (in dollars per share)	$ 4
Stock price at date of conversion (in dollars per share)	$ 18.58
Gain (loss) in estimated fair value of convertible note payable		$ (1,800,000)	$ 0	$ 0	$ 0	$ (1,811,000)

Term Loan (Details)

Term Loan (Details)	Jun. 22, 2016USD ($)	Jun. 17, 2016USD ($)loans	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)	Oct. 31, 2012USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount						$ 5,400,000
Proceeds from borrowing under term loan			$ 19,768,000	$ 0
Term loan, less debt issuance costs			19,787,000		$ 0
Debt Financing Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 30,000,000
Number of term loans | loans		2
Debt instrument, face amount			$ 20,000,000
Period to borrow additional funds - achievement of a defined milestone event until the earlier		60 days
Period for principal and interest payments		24 months
Stated interest rate, percentage		8.51%
Prepayment fee, option one			2.00%
Prepayment fee, option two			1.00%
Debt extinguishment fee			5.50%
Term loan, less debt issuance costs			$ 20,000,000
Amounts borrowed			20,000,000
Deferred finance cost			$ 200,000
Debt instrument effective rate			8.98%
Debt Financing Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate, percentage		0.44%
Debt Financing Agreement Tranche A
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 20,000,000
Proceeds from borrowing under term loan	$ 20,000,000
Term loan, less debt issuance costs			$ 20,000,000
Debt Financing Agreement Tranche B
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 10,000,000

Term Loan (Future Principal Pay

Term Loan (Future Principal Payments) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt	$ 19,787	$ 0
Debt Financing Agreement Tranche A
Debt Instrument [Line Items]
Future Repayments of Principal, 2016	0
Future Repayments of Principal, 2017	0
Future Repayments of Principal, 2018	5,000
Future Repayments of Principal, 2019	10,000
Future Repayments of Principal, 2020	5,000
Long-term Debt	$ 20,000

Stockholders' Equity (Common St

Stockholders' Equity (Common Stock Reserved for Future Issuance) (Detail) - shares	Sep. 30, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock options outstanding	6,621,106	5,126,000
Total common shares reserved for future issuance	11,245,749
Common stock available for future grant under 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant	2,448,385
Common stock available for future grant under 2015 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant	581,806
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant	1,594,452

Stockholders' Equity (Stock Opt

Stockholders' Equity (Stock Option Activity) (Detail)	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Number of options
Number of options, outstanding at December 31, 2015 (in shares) | shares	5,126,000
Number of options, Granted (in shares) | shares	2,414,000
Number of options, Exercised (in shares) | shares	(88,000)
Number of options, Canceled/forfeited/expired (in shares) | shares	(831,000)
Number of options, outstanding at September 30, 2016 (in shares) | shares	6,621,106
Weighted average exercise price
Weighted average exercise price, Options outstanding at December 31, 2015 (in dollars per share) | $ / shares	$ 8.91
Weighted average exercise price, Granted (in dollars per share) | $ / shares	6.57
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	3.50
Weighted average exercise price, Canceled/forfeited/expired (in dollars per share) | $ / shares	10.41
Weighted average exercise price, Options outstanding at September 30, 2016 (in dollars per share) | $ / shares	$ 7.94

Stockholders' Equity (Assumptio

Stockholders' Equity (Assumptions Used to Estimate Fair Value of Stock Options and Performance Stock and Employee Stock Purchase Plan) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Stock Purchase Plan
Weighted average assumptions
Risk-free interest rate	0.50%	0.20%	0.50%	0.10%
Volatility	94.50%	77.10%	85.40%	75.60%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 months	6 months	6 months	6 months
Stock options
Weighted average assumptions
Risk-free interest rate	1.50%	1.70%	1.40%	1.80%
Volatility	80.00%	78.90%	79.90%	78.80%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	5 years 8 months 12 days	6 years 1 month 6 days	5 years 10 months 24 days	6 years 1 month 6 days
Performance stock options
Weighted average assumptions
Risk-free interest rate	0.00%	1.60%	1.40%	1.80%
Volatility	0.00%	79.30%	79.30%	76.70%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	0 years	6 years 1 month 6 days	6 years	6 years

Stockholders' Equity (Stock-Bas

Stockholders' Equity (Stock-Based Compensation Expense Allocation) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 3,467	$ 2,634	$ 9,453	$ 11,607
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	1,199	1,048	3,931	6,500
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 2,268	$ 1,586	$ 5,522	$ 5,107

Strategic Alliances and Colla31

Strategic Alliances and Collaborations (Revenue from Strategic Alliances) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue from External Customer [Line Items]
Total revenues	$ 204	$ 1,865	$ 1,176	$ 9,899
Strategic Alliances and Collaborations
Revenue from External Customer [Line Items]
Total revenues	204	1,865	1,176	9,899
Strategic Alliances and Collaborations | AstraZeneca
Revenue from External Customer [Line Items]
Total revenues	186	1,380	1,122	8,028
Strategic Alliances and Collaborations | Sanofi
Revenue from External Customer [Line Items]
Total revenues	18	18	54	54
Strategic Alliances and Collaborations | Biogen
Revenue from External Customer [Line Items]
Total revenues	$ 0	$ 467	$ 0	$ 1,817

Strategic Alliances and Colla32

Strategic Alliances and Collaborations (Detail)

1 Months Ended

3 Months Ended

8 Months Ended

9 Months Ended

Dec. 31, 2015USD ($)shares

Sep. 30, 2015USD ($)

Jul. 31, 2015

May 31, 2015USD ($)

Mar. 31, 2015USD ($)

Jan. 31, 2015USD ($)

Aug. 31, 2014USD ($)

Feb. 28, 2014USD ($)$ / sharesshares

Jul. 31, 2013USD ($)

Oct. 31, 2012USD ($)$ / sharesshares

Aug. 31, 2012target

Sep. 30, 2016USD ($)shares

Sep. 30, 2015USD ($)

Jan. 31, 2014USD ($)

Sep. 30, 2016USD ($)shares

Sep. 30, 2015USD ($)

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Common stock, shares issued | shares

52,669,266

52,923,305

52,923,305

Total revenues

$ 204,000

$ 1,865,000

$ 1,176,000

$ 9,899,000

Common stock value

$ 53,000

53,000

53,000

AstraZeneca

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Number of collaborative areas granted | target

3

Initial upfront option payment

$ 3,000,000

Expected term of research and development plan (years)

4 years

Common stock, shares issued | shares

6,250,000

Price per share (in dollars per share) | $ / shares

$ 4

Restriction period in which Alliances could not sell, transfer, make any short sale of, or grant any option for the sale of any common stock

365 days

Deferred revenue

$ 4,300,000

Deferred revenue recognition period

4 years

Potential revenue through milestone payments

160,000,000

160,000,000

AstraZeneca | Preclinical

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Milestone payments, earned

$ 2,500,000

AstraZeneca | Clinical

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Milestone payments, earned

10,000,000

Potential revenue through milestone payments

32,500,000

32,500,000

AstraZeneca | Commercialization

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Potential revenue through milestone payments

127,500,000

$ 127,500,000

AstraZeneca | Side Letter

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Total revenues

$ 900,000

$ 4,100,000

AstraZeneca | Side Letter | Pre-IND and API manufacturing activities

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Percentage of cost funded

50.00%

AstraZeneca | Side Letter | Phase I clinical study product manufacturing activities

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Percentage of cost funded

100.00%

Sanofi

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Deferred revenue

$ 400,000

Sanofi | Private Placement

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Common stock, shares issued | shares

1,303,780

Price per share (in dollars per share) | $ / shares

$ 7.67

Restriction period in which Alliances could not sell, transfer, make any short sale of, or grant any option for the sale of any common stock

12 months

Common stock value

$ 10,000,000

Sanofi | Minimum | United States

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Royalties based on percentage of net sales

10.00%

Sanofi | Minimum | Outside of the United States

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Royalties based on percentage of net sales

10.00%

Sanofi | Maximum | United States

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Royalties based on percentage of net sales

20.00%

Sanofi | Maximum | Outside of the United States

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Royalties based on percentage of net sales

20.00%

Sanofi | Development Commercialization And License Agreement

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Initial upfront option payment

$ 2,500,000

Deferred revenue creditable against future milestones

$ 1,250,000

$ 1,250,000

$ 1,250,000

Upfront payment non-creditable portion recognized

$ 1,250,000

Sanofi | Common Stock Purchase Agreement

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Deferred revenue

200,000

$ 200,000

Deferred revenue recognition period

4 years

Sanofi | Clinical

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Potential revenue through milestone payments

15,000,000

$ 15,000,000

Sanofi | Proof-of-Concept Trial

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Potential revenue through milestone payments

101,800,000

101,800,000

Sanofi | Regulatory and Commercialization Milestones

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Potential revenue through milestone payments

$ 300,000,000

$ 300,000,000

Biogen

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Initial upfront option payment

$ 2,000,000

Deferred revenue

$ 0

Deferred revenue recognition period

14 months

1 year

12 months

Biogen | Research and development

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Milestone payments, earned

$ 300,000

$ 300,000

$ 100,000

Related Party Transactions (Det

Related Party Transactions (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Sanofi
Related Party Transaction [Line Items]
Expenses incurred for services performed or out-of-pocket expenses under the Sanofi agreement		$ 200,000	$ 0	$ 1,000,000	$ 400,000
Alnylam
Related Party Transaction [Line Items]
Potential milestone payments to related party	$ 33,000,000