Regulus Therapeutics (RGLS) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 24, 2015
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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		51,919,532

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 21,084	$ 37,327
Short-term investments	118,284	122,416
Contract and other receivables	616	274
Prepaid and other current assets	4,105	4,934
Total current assets	144,089	164,951
Property and equipment, net	3,310	3,568
Intangibles, net	1,072	1,150
Other assets	1,794	1,811
Total assets	150,265	171,480
Current liabilities:
Accounts payable	2,407	2,188
Accrued liabilities	6,834	4,402
Accrued compensation	2,274	2,108
Current portion of deferred revenue	3,032	3,097
Convertible note payable, at fair value		23,397
Total current liabilities	14,547	35,192
Deferred revenue, less current portion	2,287	3,252
Other long-term liabilities	804	1,022
Total liabilities	17,638	39,466
Stockholders' equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 51,533,416 and 48,944,530 shares issued and outstanding at June 30, 2015 (unaudited) and December 31, 2014, respectively	52	49
Additional paid-in capital	304,019	267,929
Accumulated other comprehensive loss	(155)	(197)
Accumulated deficit	(171,289)	(135,767)
Total stockholders' equity	132,627	132,014
Total liabilities and stockholders' equity	$ 150,265	$ 171,480

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	51,533,416	48,944,530
Common stock, shares outstanding	51,533,416	48,944,530

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Total revenues	$ 3,834	$ 736	$ 8,034	$ 2,367
Operating expenses:
Research and development	19,201	10,795	32,628	20,399
General and administrative	5,814	2,954	9,458	5,686
Total operating expenses	25,015	13,749	42,086	26,085
Loss from operations	(21,181)	(13,013)	(34,052)	(23,718)
Other income (expense):
Interest and other income	151	97	351	197
Interest expense	(7)	(10)	(16)	(21)
Gain (loss) from valuation of convertible note payable	0	953	(1,811)	(1,171)
Loss before income taxes	(21,037)	(11,973)	(35,528)	(24,713)
Income tax benefit (expense)	2		6	(1)
Net loss	(21,035)	(11,973)	(35,522)	(24,714)
Other comprehensive loss:
Unrealized (loss) gain on short-term investments, net	(2)	17	55	(26)
Comprehensive loss	$ (21,037)	$ (11,956)	$ (35,467)	$ (24,740)
Net loss per share:
Basic	$ (0.41)	$ (0.28)	$ (0.70)	$ (0.57)
Diluted	$ (0.41)	$ (0.29)	$ (0.70)	$ (0.57)
Weighted average shares used to compute net loss per share:
Basic	51,073,488	43,362,483	50,575,096	43,028,198
Diluted	51,073,488	44,799,536	50,575,096	43,028,198
Strategic Alliances and Collaborations
Revenues:
Total revenues	$ 3,834	$ 736	$ 8,034	$ 2,367

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net loss	$ (35,522)	$ (24,714)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	798	700
Loss from valuation of convertible note payable	1,811	1,171
Stock-based compensation	8,972	3,083
Amortization of premium on investments, net	801	876
Loss on disposal of long-term assets	56	18
Change in operating assets and liabilities:
Contracts and other receivables	(50)
Prepaid and other current assets	846	(1,197)
Accounts payable	130	1,729
Accrued liabilities	2,459	1,412
Accrued compensation	167	(109)
Deferred revenue	(1,323)	(1,896)
Deferred rent and other liabilities	(160)	(124)
Net cash used in operating activities	(21,015)	(19,051)
Investing activities
Purchases of short-term investments	(46,281)	(48,301)
Maturities and sales of short-term investments	49,645	50,120
Purchases of property and equipment	(410)	(731)
Acquisition of intangibles	(19)	(34)
Net cash provided by investing activities	2,935	1,054
Financing activities
Proceeds from issuance of common stock, net	257	9,728
Proceeds from exercise of common stock options	1,655	556
Principal payments on other long-term obligations	(75)	(70)
Net cash provided by financing activities	1,837	10,214
Net decrease in cash and cash equivalents	(16,243)	(7,783)
Cash and cash equivalents at beginning of period	37,327	17,807
Cash and cash equivalents at end of period	21,084	10,024
Supplemental disclosure of cash flow information
Interest paid	15	21
Income taxes paid	1	1
Supplemental disclosure of non-cash investing and financing activities
Amounts accrued for property and equipment, net	$ 90	$ 117

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Basis of Presentation and Summary of Significant Accounting Policies	1. 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 Company’s audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2014, 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. 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 that 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”) and our collaboration agreement with Biogen Inc. (“Biogen”), formerly Biogen Idec MA Inc., 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 over our estimated period of performance, which for us is often 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 acknowledgement 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 related 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. In July 2012, we amended and restated the $5.0 million convertible promissory note originally issued in February 2010 to Glaxo Group Limited (“GSK”) (the “2010 GSK Note”), which resulted in a debt extinguishment for accounting purposes. Concurrently with the debt extinguishment, we elected the fair value option for the 2010 GSK Note. The difference between the carrying value of the 2010 GSK Note and the fair value of the amended and restated 2010 GSK Note was recorded as a loss on extinguishment of debt to non-operating earnings. Thereafter, any change to the fair value of the amended note was recorded as gain (loss) from valuation of convertible note payable to non-operating earnings. The amended and restated 2010 GSK Note provided for a rollover into a new promissory note, effective as of the closing date of a qualifying initial public offering (the “Post-IPO GSK Note”). In October 2012, upon our initial public offering, the Post-IPO GSK Note was established in the principal amount of $5.4 million, which was equivalent to the original principal amount of $5.0 million plus accrued but unpaid interest of approximately $0.4 million. The 2010 GSK Note was simultaneously cancelled and obligations thereunder were terminated. In January 2015, the principal balance of the Post-IPO GSK Note was converted into common stock. Clinical Trial and Pre-Clinical Study Accruals We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. Our accrued expenses for pre-clinical studies and clinical trials are based on estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites, clinical research organizations (“CROs”) and other clinical trial-related vendors. 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 service fees, 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 activity 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. Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2015
Net Loss Per Share	2. Net Loss Per Share Basic net loss per share is calculated by dividing the 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 the 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 plan and convertible note payable. Applicable accounting standards provides that a contract convertible into common stock that is reported as an asset or liability for accounting purposes may require an adjustment to the numerator of the diluted earnings per share calculation for any changes in income or loss that would result if the contract had been reported as an equity instrument during the period. Securities are assumed to be converted at the beginning of the period, and the resulting common shares are included in the denominator of the diluted earnings per share calculation for the entire period presented. Adding back the gain from the change in valuation of the convertible note payable for the three months ended June 30, 2014 to the numerator and adding the number of shares to be issued upon conversion of the convertible note payable into the denominator of the diluted earnings per share calculation resulted in an increase to the loss per share for the period. There is no difference in net loss or the number of shares used to calculate basic and diluted shares outstanding for the three months ended June 30, 2015 and the six months ended June 30, 2015 and 2014, respectively. The following table summarizes the adjustment to net loss for the diluted net loss per share calculation for the three months ended June 30, 2014 (in thousands): Net loss $ (11,973 ) Less: gain from change in valuation of note payable 953 Net loss used to compute diluted net loss per share $ (12,926 ) The following table summarizes the adjustment to weighted average shares outstanding for the diluted net loss per share calculation for the three months ended June 30, 2014 (in common equivalent shares): Weighted average shares outstanding used for basic net loss per share 43,362,483 Plus: weighted average shares of convertible note payable 1,437,053 Weighted average shares outstanding used for diluted net loss per share 44,799,536 Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common equivalent shares): Three months ended Six months ended 2015 2014 2015 2014 Common stock options 2,905,340 2,052,638 3,331,699 2,607,245 Convertible note payable — — — 1,437,053 Total 2,905,340 2,052,638 3,331,699 4,044,298

Investments

Investments	6 Months Ended
	Jun. 30, 2015
Investments	3. Investments We invest our excess cash in commercial paper and debt instruments of financial institutions and corporations. As of June 30, 2015, 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 Amortized Unrealized Estimated Gains Losses As of June 30, 2015 Corporate debt securities 2 or less $ 97,934 $ 5 $ (114 ) $ 97,825 Certificates of deposit 2 or less 16,760 — — 16,760 Commercial paper 1 or less 3,698 1 — 3,699 Total $ 118,392 $ 6 $ (114 ) $ 118,284 Maturity Amortized Unrealized Estimated Gains Losses As of December 31, 2014 Corporate debt securities 2 or less $ 105,085 $ 2 $ (167 ) $ 104,920 Certificates of deposit 2 or less 14,600 — — 14,600 Commercial paper 1 or less 2,895 1 — 2,896 Total $ 122,580 $ 3 $ (167 ) $ 122,416

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
Fair Value Measurements	4. Fair Value Measurements We have certain financial assets and liabilities 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. The following table presents our fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of June 30, 2015 and December 31, 2014 (in thousands): Fair value as of June 30, 2015 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 19,578 $ 19,578 $ — $ — Corporate debt securities 97,825 — 97,825 — Certificates of deposit 16,760 — 16,760 — Commercial paper 3,699 — 3,699 — $ 137,862 $ 19,578 $ 118,284 $ — Fair value as of December 31, 2014 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 37,072 $ 37,072 $ — $ — Corporate debt securities 104,920 — 104,920 — Certificates of deposit 14,600 — 14,600 — Commercial paper 2,896 — 2,896 — $ 159,488 $ 37,072 $ 122,416 $ — Liabilities: Convertible note payable $ 23,397 $ — $ — $ 23,397 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. The following table presents a reconciliation of the liability measured at fair value using significant unobservable inputs (Level 3) from December 31, 2014 to June 30, 2015 (in thousands): Fair Value Measurements Balance at December 31, 2014 $ 23,397 Change in estimated fair value of convertible note payable 1,811 Convertible note converted to shares of common stock (25,208 ) Balance at June 30, 2015 $ — We used an income approach in the form of a convertible bond valuation model to value the convertible note payable. The convertible bond model considered the debt and option characteristics of the note. The key inputs to the model as of December 31, 2014 were volatility of 110%, risk-free rate of 0.10% and credit spread of 9.7%. The volatility inputs were based on historical and implied volatility of peer companies. Peer companies were materially consistent with those used to determine volatility for stock-based compensation. Beginning in 2014, our historical volatility was included with the peer companies for purposes of estimating volatility. As of December 31, 2014, the volatility input included 60% weighting of our historical volatility and 40% weighting of historical and implied volatility of peer companies. The risk-free rate inputs were based on the yield of US Treasury Strips as of each date. The credit spread inputs were based on an analysis of our creditworthiness and market rates for comparable straight debt instruments. On January 29, 2015, the principal balance of the convertible note payable was converted into 1,356,738 shares of common stock, at a conversion price of $4.00 per share. A final valuation upon conversion at January 29, 2015 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 zero and $1.8 million on the condensed statements of operations and comprehensive loss for the three and six months ended June 30, 2015, respectively. We recorded a gain of $1.0 million for the three months ended June 30, 2014 and a loss of $1.2 million for the six months ended June 30, 2014.

Convertible Note Payable

Convertible Note Payable	6 Months Ended
	Jun. 30, 2015
Convertible Note Payable	5. Convertible Note Payable In October 2012, in conjunction with our initial public offering the amended and restated 2010 GSK Note was rolled over into a new promissory note, and the Post-IPO GSK Note was established in the principal amount of $5.4 million, with a maturity date of October 9, 2015. At December 31, 2014, the fair value of the Post-IPO GSK Note was $23.4 million and was classified as “Convertible note payable, at fair value” on the condensed balance sheets. 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.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2015
Stockholders' Equity	6. Stockholders’ Equity Shares Reserved for Future Issuance The following shares of common stock were reserved for future issuance as of June 30, 2015: Common stock options outstanding 6,064,456 Common stock available for future grant 1,672,578 Employee Stock Purchase Plan 1,291,834 Total common shares reserved for future issuance 9,028,868 The following table summarizes our stock option activity under all equity incentive plans for the six months ended June 30, 2015 (shares in thousands): Number of Weighted Options outstanding at December 31, 2014 6,643 $ 6.95 Granted 1,141 $ 12.50 Exercised (1,206 ) $ 1.48 Canceled/forfeited/expired (514 ) $ 11.32 Options outstanding at June 30, 2015 6,064 $ 8.71 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 the shares purchasable under our 2012 Employee Stock Purchase Plan during the periods presented: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Stock options Risk-free interest rate 1.8 % 1.9 % 1.8 % 1.9 % Volatility 79.1 % 72.4 % 78.8 % 73.1 % Dividend yield 0 % 0 % 0 % 0 % Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — 2.0 % 1.8 % 2.1 % Volatility — 69.0 % 76.4 % 69.6 % Dividend yield — 0 % 0 % 0 % Expected term (years) — 6.3 6.0 6.3 Employee stock purchase plan shares Risk-free interest rate 0.1 % 0.1 % 0.1 % 0.1 % Volatility 76.9 % 71.5 % 74.9 % 68.4 % Dividend yield 0 % 0 % 0 % 0 % 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 Six months ended June 30, 2015 2014 2015 2014 Research and development $ 3,496 $ 854 $ 5,452 $ 1,658 General and administrative 2,373 830 3,520 1,425 Total $ 5,869 $ 1,684 $ 8,972 $ 3,083

Strategic Alliances and Collabo

Strategic Alliances and Collaborations	6 Months Ended
	Jun. 30, 2015
Strategic Alliances and Collaborations	7. 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 Six months ended 2015 2014 2015 2014 AstraZeneca $ 3,066 $ 465 $ 6,648 $ 929 Sanofi 18 18 36 944 GSK — 144 — 288 Biogen 750 86 1,350 173 Other — 23 — 33 Total $ 3,834 $ 736 $ 8,034 $ 2,367 AstraZeneca In August 2012, we entered into a collaboration and license agreement with AstraZeneca. Under the terms of the agreement, we have agreed to collaborate with AstraZeneca to identify, research and develop compounds targeting three micro 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, does not have stand-alone value. As a result, we are recognizing revenue related to the upfront payment on a straight-line basis over our estimated period of performance, which is four years based on the expected term of the research and development plan. 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 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 have agreed to perform additional miR-103/107 program research and development activities related to RG-125. AstraZeneca has agreed to fund 50% of the costs for additional activities, as outlined in the letter agreement. In accordance with the collaboration and license agreement, AstraZeneca will fund 100% of the costs for product manufacturing activities outlined in the letter agreement necessary to support a Phase I clinical study. We have recognized $2.6 million and $3.2 million for the three and six months ended June 30, 2015, respectively, for the performance of research and development and product manufacturing activities outlined in the letter agreement. As of June 30, 2015, deferred revenue from advanced payments associated with the letter agreement was $0.9 million, which we will recognize in the period services are provided. We have evaluated the contingent event-based payments under our collaboration and license agreement with AstraZeneca and determined that the preclinical payments meet the definition of substantive milestones. Accordingly, revenue for these achievements will be recognized in its entirety in the period when the milestone is achieved and collectability is 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. Concurrently with the collaboration and license agreement, we entered into a Common Stock Purchase Agreement (“CSPA”) with AstraZeneca, pursuant to which we agreed to sell to AstraZeneca an aggregate of $25.0 million of our common stock in a private placement concurrently with our initial public offering, at a price per share equal to the initial public offering price. In October 2012, in accordance with the CSPA, we sold AstraZeneca 6,250,000 shares of our common stock at a price per share of $4.00. Further, the CSPA stipulated that 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. Accounting standards for multiple element arrangements contains a presumption that separate contracts negotiated and/or entered into at or near the same time with the same entity were negotiated as a package and should be evaluated as a single agreement. We valued the discount applied to the shares of common stock due to the one-year restriction. 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 continue to recognize the $4.3 million into revenue ratably over the estimated period of performance of the collaboration. As of June 30, 2015, deferred revenue associated with the collaboration and license agreement and CSPA was $2.0 million, which we are expecting to recognize over the remaining contractual term and corresponding estimated period of performance of approximately one year. Sanofi In July 2012, we amended and restated our collaboration and license agreement with Sanofi to expand the potential therapeutic applications of the micro micro 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 In conjunction with the option agreement, we agreed to continue specified research on the miR-21 programs during the option period. We re-evaluated our remaining estimated period of performance from the original research term through the term of the option agreement and amortized the remaining deferred revenue of $10.1 million associated with the initial $25.0 million upfront payment from 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 micro 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 June 30, 2015, deferred revenue associated with the Purchase Agreement and the 2014 Sanofi Amendment was $0.3 million, which we are expecting to recognize over the remaining estimated period of performance of approximately five 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. GSK In April 2008, we entered into a strategic alliance with GSK to discover, develop and commercialize novel micro micro micro In June 2013, the HCV alliance was amended to state that RG-101, and other formulations thereof, will be developed by us independently of our alliance for the treatment of HCV. This amendment removed any further milestone or royalty obligations owed by GSK to us as it relates to RG-101. Concurrently with the amendment, we recorded the remaining $1.1 million in deferred revenue associated with the upfront payment from the HCV alliance, as our estimated period of performance was complete. In October 2014, we received written notice from GSK of its election to terminate the product development and commercialization agreement. Concurrently with the notice of termination, we recorded the remaining $3.1 million in deferred revenue associated with the upfront payment, as our estimated period of performance was complete. The effective date of the termination was January 15, 2015, in accordance with the terms of the agreement. Biogen In August 2012, we entered into a collaboration and license agreement with Biogen pursuant to which we and Biogen agreed to collaborate on micro In June 2013, we amended the collaboration and license agreement to provide for revised terms with respect to the initial phase of the research plan and related milestone payment provisions. The amendment did not modify the maximum dollar amount we were originally eligible to receive in connection with the agreement, or our estimated period of performance. In October 2013 and November 2013, we received research milestone payments totaling $0.3 million under the August 2012 collaboration and license agreement. In August 2014, we entered into a new collaboration and license agreement with Biogen to collaborate on micro We have evaluated the contingent event-based payments under our collaboration and license agreement with Biogen and determined that the research 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. As of June 30, 2015, deferred revenue associated with the collaboration and license agreement was $0.2 million, which we are expecting to recognize over the remaining contractual term and corresponding estimated period of performance of approximately one month.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2015
Related Party Transactions	8. Related Party Transactions We have entered into several 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 February 2015, we entered into a letter agreement with Alnylam pursuant to which we and Alnylam agreed to the financial terms for certain technology acquired by Alnylam within the licensed patent rights under the Amended and Restated License and Collaboration Agreement (the “Additional Patent Rights”). In addition to any royalties payable by us to Alnylam pursuant to the terms of the Amended and Restated 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 six months ended June 30, 2015. 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 zero and $0.4 million for the three and six months ended June 30, 2015, respectively.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2015
Subsequent Events	9. Subsequent Events In July 2015, we entered into a lease agreement (“Lease”) with Walton Torrey Owner B, L.L.C. to relocate our corporate headquarters and research facility to a new location at 10614 Science Center Drive, San Diego, California. Pursuant to the Lease, we will increase our office and lab space to approximately 59,000 square feet. The Lease term is expected to commence in the first half of 2016 and expires 96 months after the Commencement Date. We have an option to extend the Lease for an additional five years.

Basis of Presentation and Sum15

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
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 Company’s audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2014, 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. 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 that 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”) and our collaboration agreement with Biogen Inc. (“Biogen”), formerly Biogen Idec MA Inc., 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 over our estimated period of performance, which for us is often 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 acknowledgement 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 related 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. In July 2012, we amended and restated the $5.0 million convertible promissory note originally issued in February 2010 to Glaxo Group Limited (“GSK”) (the “2010 GSK Note”), which resulted in a debt extinguishment for accounting purposes. Concurrently with the debt extinguishment, we elected the fair value option for the 2010 GSK Note. The difference between the carrying value of the 2010 GSK Note and the fair value of the amended and restated 2010 GSK Note was recorded as a loss on extinguishment of debt to non-operating earnings. Thereafter, any change to the fair value of the amended note was recorded as gain (loss) from valuation of convertible note payable to non-operating earnings. The amended and restated 2010 GSK Note provided for a rollover into a new promissory note, effective as of the closing date of a qualifying initial public offering (the “Post-IPO GSK Note”). In October 2012, upon our initial public offering, the Post-IPO GSK Note was established in the principal amount of $5.4 million, which was equivalent to the original principal amount of $5.0 million plus accrued but unpaid interest of approximately $0.4 million. The 2010 GSK Note was simultaneously cancelled and obligations thereunder were terminated. In January 2015, the principal balance of the Post-IPO GSK Note was converted into common stock.
Clinical Trial and Pre-Clinical Study Accruals	Clinical Trial and Pre-Clinical Study Accruals We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. Our accrued expenses for pre-clinical studies and clinical trials are based on estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites, clinical research organizations (“CROs”) and other clinical trial-related vendors. 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 service fees, 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 activity 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2015
Summary of Adjustment for Net Loss for Diluted Net Loss per Share Calculation	The following table summarizes the adjustment to net loss for the diluted net loss per share calculation for the three months ended June 30, 2014 (in thousands): Net loss $ (11,973 ) Less: gain from change in valuation of note payable 953 Net loss used to compute diluted net loss per share $ (12,926 )
Weighted Average Shares Outstanding for Diluted Net Loss per Share	The following table summarizes the adjustment to weighted average shares outstanding for the diluted net loss per share calculation for the three months ended June 30, 2014 (in common equivalent shares): Weighted average shares outstanding used for basic net loss per share 43,362,483 Plus: weighted average shares of convertible note payable 1,437,053 Weighted average shares outstanding used for diluted net loss per share 44,799,536
Potentially Dilutive Securities Not Included in Calculation of 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 are as follows (in common equivalent shares): Three months ended Six months ended 2015 2014 2015 2014 Common stock options 2,905,340 2,052,638 3,331,699 2,607,245 Convertible note payable — — — 1,437,053 Total 2,905,340 2,052,638 3,331,699 4,044,298

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2015
Summary of Short-Term Investments	The following tables summarize our short-term investments (in thousands): Maturity Amortized Unrealized Estimated Gains Losses As of June 30, 2015 Corporate debt securities 2 or less $ 97,934 $ 5 $ (114 ) $ 97,825 Certificates of deposit 2 or less 16,760 — — 16,760 Commercial paper 1 or less 3,698 1 — 3,699 Total $ 118,392 $ 6 $ (114 ) $ 118,284 Maturity Amortized Unrealized Estimated Gains Losses As of December 31, 2014 Corporate debt securities 2 or less $ 105,085 $ 2 $ (167 ) $ 104,920 Certificates of deposit 2 or less 14,600 — — 14,600 Commercial paper 1 or less 2,895 1 — 2,896 Total $ 122,580 $ 3 $ (167 ) $ 122,416

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents our fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of June 30, 2015 and December 31, 2014 (in thousands): Fair value as of June 30, 2015 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 19,578 $ 19,578 $ — $ — Corporate debt securities 97,825 — 97,825 — Certificates of deposit 16,760 — 16,760 — Commercial paper 3,699 — 3,699 — $ 137,862 $ 19,578 $ 118,284 $ — Fair value as of December 31, 2014 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 37,072 $ 37,072 $ — $ — Corporate debt securities 104,920 — 104,920 — Certificates of deposit 14,600 — 14,600 — Commercial paper 2,896 — 2,896 — $ 159,488 $ 37,072 $ 122,416 $ — Liabilities: Convertible note payable $ 23,397 $ — $ — $ 23,397
Reconciliation of Liabilities Measured at Fair Value on Quarterly Basis	The following table presents a reconciliation of the liability measured at fair value using significant unobservable inputs (Level 3) from December 31, 2014 to June 30, 2015 (in thousands): Fair Value Measurements Balance at December 31, 2014 $ 23,397 Change in estimated fair value of convertible note payable 1,811 Convertible note converted to shares of common stock (25,208 ) Balance at June 30, 2015 $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2015
Common Stock Reserved for Future Issuance	The following shares of common stock were reserved for future issuance as of June 30, 2015: Common stock options outstanding 6,064,456 Common stock available for future grant 1,672,578 Employee Stock Purchase Plan 1,291,834 Total common shares reserved for future issuance 9,028,868
Stock Option Activity	The following table summarizes our stock option activity under all equity incentive plans for the six months ended June 30, 2015 (shares in thousands): Number of Weighted Options outstanding at December 31, 2014 6,643 $ 6.95 Granted 1,141 $ 12.50 Exercised (1,206 ) $ 1.48 Canceled/forfeited/expired (514 ) $ 11.32 Options outstanding at June 30, 2015 6,064 $ 8.71
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 the shares purchasable under our 2012 Employee Stock Purchase Plan during the periods presented: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Stock options Risk-free interest rate 1.8 % 1.9 % 1.8 % 1.9 % Volatility 79.1 % 72.4 % 78.8 % 73.1 % Dividend yield 0 % 0 % 0 % 0 % Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — 2.0 % 1.8 % 2.1 % Volatility — 69.0 % 76.4 % 69.6 % Dividend yield — 0 % 0 % 0 % Expected term (years) — 6.3 6.0 6.3 Employee stock purchase plan shares Risk-free interest rate 0.1 % 0.1 % 0.1 % 0.1 % Volatility 76.9 % 71.5 % 74.9 % 68.4 % Dividend yield 0 % 0 % 0 % 0 % 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 Six months ended June 30, 2015 2014 2015 2014 Research and development $ 3,496 $ 854 $ 5,452 $ 1,658 General and administrative 2,373 830 3,520 1,425 Total $ 5,869 $ 1,684 $ 8,972 $ 3,083

Strategic Alliances and Colla20

Strategic Alliances and Collaborations (Tables)	6 Months Ended
	Jun. 30, 2015
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 Six months ended 2015 2014 2015 2014 AstraZeneca $ 3,066 $ 465 $ 6,648 $ 929 Sanofi 18 18 36 944 GSK — 144 — 288 Biogen 750 86 1,350 173 Other — 23 — 33 Total $ 3,834 $ 736 $ 8,034 $ 2,367

Basis of Presentation and Sum21

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - Convertible Debt - USD ($) $ in Millions	Oct. 31, 2012	Jul. 31, 2012
Organization And Summary Of Significant Accounting Policies [Line Items]
Outstanding principal amount	$ 5	$ 5
Accrued and unpaid interest on convertible note	0.4
GSK
Organization And Summary Of Significant Accounting Policies [Line Items]
Outstanding principal amount	$ 5.4

Summary of Adjustment for net L

Summary of Adjustment for net Loss for Diluted Net Loss per Share Calculation (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Dilutive Securities Included In Computation Of Earnings Per Share [Line Items]
Net loss	$ (21,035)	$ (11,973)	$ (35,522)	$ (24,714)
Less: gain from change in valuation of note payable	$ 0	953	$ (1,811)	$ (1,171)
Net loss used to compute diluted net loss per share		$ (12,926)

Weighted Average Shares Outstan

Weighted Average Shares Outstanding for Diluted Net Loss per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding used for basic net loss per share	51,073,488	43,362,483	50,575,096	43,028,198
Plus: weighted average shares of convertible note payable		1,437,053
Weighted average shares outstanding used for diluted net loss per share	51,073,488	44,799,536	50,575,096	43,028,198

Potentially Dilutive Securities

Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of diluted net loss per share	2,905,340	2,052,638	3,331,699	4,044,298
Common Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of diluted net loss per share	2,905,340	2,052,638	3,331,699	2,607,245
Convertible Note Payable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of diluted net loss per share				1,437,053

Summary of Short-Term Investmen

Summary of Short-Term Investments (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Investment [Line Items]
Amortized cost	$ 118,392	$ 122,580
Unrealized Gains	6	3
Unrealized Losses	(114)	(167)
Estimated fair value	$ 118,284	$ 122,416
Corporate Debt Securities
Investment [Line Items]
Maturity
Amortized cost	$ 97,934	$ 105,085
Unrealized Gains	5	2
Unrealized Losses	(114)	(167)
Estimated fair value	$ 97,825	$ 104,920
Certificates of Deposit
Investment [Line Items]
Maturity
Amortized cost	$ 16,760	$ 14,600
Estimated fair value	$ 16,760	$ 14,600
Commercial Paper
Investment [Line Items]
Maturity
Amortized cost	$ 3,698	$ 2,895
Unrealized Gains	1	1
Estimated fair value	$ 3,699	$ 2,896

Fair Value Hierarchy for Assets

Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 137,862	$ 159,488
Convertible Note Payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities measured at fair value on a recurring basis		23,397
Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	19,578	37,072
Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	97,825	104,920
Certificates of Deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	16,760	14,600
Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	3,699	2,896
Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	19,578	37,072
Fair Value, Inputs, Level 1 | Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	19,578	37,072
Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	118,284	122,416
Fair Value, Inputs, Level 2 | Corporate Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	97,825	104,920
Fair Value, Inputs, Level 2 | Certificates of Deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	16,760	14,600
Fair Value, Inputs, Level 2 | Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 3,699	2,896
Fair Value, Inputs, Level 3 | Convertible Note Payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities measured at fair value on a recurring basis		$ 23,397

Reconciliation of Liabilities M

Reconciliation of Liabilities Measured at Fair Value on Quarterly Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in estimated fair value of convertible note payable	$ 0	$ 953	$ (1,811)	$ (1,171)
Fair Value, Inputs, Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2014			23,397
Change in estimated fair value of convertible note payable			1,811
Convertible note converted to shares of common stock			$ (25,208)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 29, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption, volatility rate						110.00%
Fair value assumption, risk free rate						0.10%
Fair value assumption, credit spread						9.70%
Number of convertible note payable converted in to common stock	1,356,738
Conversion price per share	$ 4	$ 4		$ 4
Stock price at date of conversion	$ 18.58
Change in estimated fair value of convertible note payable		$ 0	$ 953	$ (1,811)	$ (1,171)
Historical Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption, volatility rate, weighting						60.00%
Implied Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption, volatility rate, weighting						40.00%

Convertible Note Payable - Addi

Convertible Note Payable - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jan. 29, 2015	Jun. 30, 2015	Dec. 31, 2014	Oct. 31, 2012	Jul. 31, 2012
Debt Instrument [Line Items]
Conversion date		Oct. 9, 2015
Conversion price per share	$ 4	$ 4
Convertible note payable, at fair value			$ 23.4
Number of convertible note payable converted in to common stock	1,356,738
Convertible Debt
Debt Instrument [Line Items]
Outstanding principal amount				$ 5	$ 5
Convertible Debt | GSK
Debt Instrument [Line Items]
Outstanding principal amount				$ 5.4

Common Stock Reserved for Futur

Common Stock Reserved for Future Issuance (Detail) - shares	Jun. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock options outstanding	6,064,456	6,643,000
Common stock available for future grant	1,672,578
Total common shares reserved for future issuance	9,028,868
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant	1,291,834

Stock Option Activity (Detail)

Stock Option Activity (Detail) - 6 months ended Jun. 30, 2015 - $ / shares	Total
Number of options
Options outstanding at December 31, 2014	6,643,000
Granted	1,141,000
Exercised	(1,206,000)
Canceled/forfeited/expired	(514,000)
Options outstanding at June 30, 2015	6,064,456
Weighted average exercise price
Options outstanding at December 31, 2014	$ 6.95
Granted	12.50
Exercised	1.48
Canceled/forfeited/expired	11.32
Options outstanding at June 30, 2015	$ 8.71

Assumptions Used to Estimate Fa

Assumptions Used to Estimate Fair Value of Stock Options and Performance Stock and Employee Stock Purchase Plan (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Common stock options
Weighted average assumptions
Risk-free interest rate	1.80%	1.90%	1.80%	1.90%
Volatility	79.10%	72.40%	78.80%	73.10%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Performance stock options
Weighted average assumptions
Risk-free interest rate		2.00%	1.80%	2.10%
Volatility		69.00%	76.40%	69.60%
Dividend yield		0.00%	0.00%	0.00%
Expected term (years)		6 years 3 months 18 days	6 years 3 months 18 days	6 years 3 months 18 days
Employee Stock Purchase Plan
Weighted average assumptions
Risk-free interest rate	0.10%	0.10%	0.10%	0.10%
Volatility	76.90%	71.50%	74.90%	68.40%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 months	6 months	6 months	6 months

Stock-Based Compensation (Detai

Stock-Based Compensation (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 5,869	$ 1,684	$ 8,972	$ 3,083
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	3,496	854	5,452	1,658
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 2,373	$ 830	$ 3,520	$ 1,425

Revenue from Strategic Alliance

Revenue from Strategic Alliances (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue from External Customer [Line Items]
Total revenues	$ 3,834	$ 736	$ 8,034	$ 2,367
Strategic Alliances and Collaborations
Revenue from External Customer [Line Items]
Total revenues	3,834	736	8,034	2,367
Strategic Alliances and Collaborations | Astra Zeneca
Revenue from External Customer [Line Items]
Total revenues	3,066	465	6,648	929
Strategic Alliances and Collaborations | Sanofi
Revenue from External Customer [Line Items]
Total revenues	18	18	36	944
Strategic Alliances and Collaborations | GSK
Revenue from External Customer [Line Items]
Total revenues		144		288
Strategic Alliances and Collaborations | Biogen
Revenue from External Customer [Line Items]
Total revenues	$ 750	86	$ 1,350	173
Strategic Alliances and Collaborations | Other
Revenue from External Customer [Line Items]
Total revenues		$ 23		$ 33

Strategic Alliances and Colla35

Strategic Alliances and Collaborations - Additional Information (Detail) $ / shares in Units, $ in Thousands

1 Months Ended

3 Months Ended

6 Months Ended

May. 31, 2015USD ($)

Mar. 31, 2015USD ($)

Jan. 31, 2015USD ($)

Oct. 31, 2014USD ($)

Aug. 31, 2014USD ($)

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

Jul. 31, 2013USD ($)

Jun. 30, 2013USD ($)

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

Aug. 31, 2012USD ($)

Jun. 30, 2015USD ($)shares

Jun. 30, 2015USD ($)Agreementshares

Dec. 31, 2014USD ($)shares

Nov. 30, 2013USD ($)

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

Common stock value

$ 52

$ 52

$ 49

Common stock, shares issued | shares

51,533,416

51,533,416

48,944,530

Sanofi

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

Deferred revenue

$ 400

Deferred revenue remaining recognition period

5 years

Sanofi | Private Placement

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

Common stock value

$ 10,000

Common stock, shares issued | shares

1,303,780

Price 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

Sanofi | Development Commercialization And License Agreement

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

Initial upfront option payment

$ 2,500

$ 2,500

Upfront payment creditable against future accounts receivables

$ 1,250

$ 1,250

Upfront payment non-creditable portion recognized

$ 1,250

Sanofi | Research and development

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

Initial upfront option payment

$ 25,000

Deferred revenue

$ 10,100

$ 10,100

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 | Proof-of-Concept Trial

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

Revenue through milestone payments

101,800

$ 101,800

Sanofi | Clinical

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

Revenue through milestone payments

15,000

15,000

Sanofi | Regulatory and Commercialization Milestones

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

Revenue through milestone payments

300,000

300,000

Sanofi | Common Stock Purchase Agreement

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

Deferred revenue

300

$ 300

Astra Zeneca

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

Number of collaborative areas granted | Agreement

3

Collaboration and license agreement date

2012-08

Initial upfront option payment

$ 3,000

Expected term of research and development plan

4 years

Revenue through milestone payments

495,500

495,500

Deferred revenue

$ 4,300

2,000

2,000

Common stock value

25,000

$ 25,000

Common stock, shares issued | shares

6,250,000

Price 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

Restricting common stock valuation measurement period

1 year

Deferred revenue remaining recognition period

1 year

Astra Zeneca | Minimum

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

Royalties based on percentage of net sales

10.00%

Astra Zeneca | Maximum

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

Royalties based on percentage of net sales

20.00%

Astra Zeneca | Clinical

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

Revenue through milestone payments

123,000

$ 123,000

Astra Zeneca | Preclinical

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

Revenue through milestone payments

2,500

2,500

Milestone payments, earned

$ 2,500

Astra Zeneca | Commercialization

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

Revenue through milestone payments

370,000

370,000

Astra Zeneca | Side Letter

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

Revenue recognized

2,600

3,200

Deferred revenue

900

$ 900

Astra Zeneca | Side Letter | Pre-IND and API manufacturing activities

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

Percentage of cost funded

100.00%

Astra Zeneca | Side Letter | Phase I clinical study product manufacturing activities

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

Percentage of cost funded

50.00%

GSK

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

Deferred revenue recognition period

8 years

Acceleration of remaining amortization of upfront payment

$ 3,100

$ 1,100

Biogen

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

Initial upfront option payment

$ 2,000

$ 800

Deferred revenue

$ 200

$ 200

Deferred revenue remaining recognition period

1 year

1 month

Acceleration of remaining amortization of upfront payment

$ 100

Revenue recognition period

2 years

Biogen | Research and development

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

Milestone payments, earned

$ 300

$ 100

Deferred revenue

2,000

Additional milestone payments

$ 300

Biogen | Research Tax Credit Carryforward

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

Revenue through milestone payments

$ 1,300

Biogen | Amended Collaboration and License Agreement

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

Revenue through milestone payments

$ 300

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 28, 2015	Jun. 30, 2015	Jun. 30, 2015
Alnylam
Related Party Transaction [Line Items]
Milestone payments to related party	$ 33
Sanofi
Related Party Transaction [Line Items]
Expenses incurred for services performed or out-of-pocket expenses under the Sanofi agreement		$ 0	$ 0.4

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Jul. 31, 2015 - Subsequent Event - Walton Torrey - ft²	Total
Subsequent Event [Line Items]
Area of premises leased	59,000
Lease commencement date	First half of 2016
Lease expiration term	96 months after the Commencement Date
Lease extension term	5 years