Regulus Therapeutics (RGLS) 10-Q 9 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
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		8,750,343
Entity Small Business	false
Entity Emerging Growth Company	false

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 14,084	$ 13,519
Short-term investments	6,433	46,555
Contract and other receivables	13	373
Prepaid materials, net	4,194	4,783
Prepaid expenses and other current assets	717	1,506
Total current assets	25,441	66,736
Property and equipment, net	8,324	9,708
Intangibles, net	676	775
Other assets	327	590
Total assets	34,768	77,809
Current liabilities:
Accounts payable	1,235	5,743
Accrued liabilities	1,856	2,995
Accrued compensation	1,292	1,985
Current portion of term loan, less debt issuance costs	19,069	19,859
Current portion of contract liabilities	72	0
Other current liabilities	2,130	2,018
Total current liabilities	25,654	32,600
Contract liabilities, less current portion	24	1,921
Deferred rent, less current portion	7,139	8,072
Other long-term liabilities	373	0
Total liabilities	33,190	42,593
Commitments and Contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 8,750,343 and 8,662,435 shares issued and outstanding at September 30, 2018 (unaudited) and December 31, 2017, respectively	9	9
Additional paid-in capital	385,793	381,199
Accumulated other comprehensive loss	(63)	(134)
Accumulated deficit	(384,161)	(345,858)
Total stockholders’ equity	1,578	35,216
Total liabilities and stockholders’ equity	$ 34,768	$ 77,809

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (shares)	200,000,000	200,000,000
Common stock, shares issued (shares)	8,750,343	8,662,435
Common stock, shares outstanding (shares)	8,750,343	8,662,435

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 18	$ 18	$ 54	$ 54
Operating expenses:
Research and development	6,879	12,697	28,720	42,727
General and administrative	2,993	2,736	10,115	13,752
Total operating expenses	9,872	15,433	38,835	56,479
Loss from operations	(9,854)	(15,415)	(38,781)	(56,425)
Other income (expense):
Interest and other income	201	160	483	559
Interest and other expense	(620)	(580)	(1,848)	(1,730)
Loss before income taxes	(10,273)	(15,835)	(40,146)	(57,596)
Income tax benefit	0	7	0	139
Net loss	(10,273)	(15,828)	(40,146)	(57,457)
Other comprehensive loss:
Unrealized gain (loss) on short-term investments, net	16	(16)	70	19
Comprehensive loss	$ (10,257)	$ (15,844)	$ (40,076)	$ (57,438)
Net loss per share, basic and diluted (in dollars per share)	$ (1.18)	$ (2.11)	$ (4.62)	$ (10.52)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	8,703,626	7,506,529	8,688,831	5,463,096
Revenue under strategic alliances and collaborations
Revenues:
Total revenues	$ 18	$ 18	$ 54	$ 54

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net loss	$ (40,146)	$ (57,457)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	1,672	1,942
Stock-based compensation	4,374	6,531
Amortization of premium on investments, net	92	271
Other	182	206
Change in operating assets and liabilities:
Contracts and other receivables	360	1,124
Prepaid materials	589	(360)
Prepaid expenses and other assets	1,050	2,405
Accounts payable	(4,509)	(579)
Accrued liabilities	(1,138)	(652)
Accrued compensation	(693)	(631)
Contract liabilities	(54)	(54)
Deferred rent and other liabilities	(1,035)	(418)
Net cash used in operating activities	(39,256)	(47,672)
Investing activities
Purchases of short-term investments	0	(48,539)
Sales and maturities of short-term investments	40,101	58,310
Purchases of property and equipment	(22)	(217)
Acquisition of intangibles	0	(16)
Net cash provided by investing activities	40,079	9,538
Financing activities
Proceeds from issuance of common stock, net	219	43,411
Proceeds from exercise of common stock options	2	4
Principal payments on other long-term obligations	(833)	0
Proceeds from capital lease financing	354	0
Net cash used in financing activities	(258)	43,415
Net increase in cash and cash equivalents	565	5,281
Cash and cash equivalents at beginning of period	13,519	14,941
Cash and cash equivalents at end of period	14,084	20,222
Supplemental disclosure of cash flow information
Interest paid	(1,573)	(1,444)
Income taxes paid	(1)	(1)
Supplemental disclosure of non-cash investing and financing activities
Non-cash acquisition of property and equipment	$ 306	$ 0

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
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, 2017 , from which the balance sheet information herein was derived. In May 2017, we implemented a corporate restructuring to streamline our operations, reduce our operating expenses, extend our cash runway and focus our resources on our most promising programs. In connection with the restructuring, we reduced our total workforce by approximately 30% , to approximately 65 employees. We completed the workforce reduction in June 2017. In July 2018, we implemented a second corporate restructuring to further reduce operating expenses and focus our resources, which involved an additional reduction in our workforce of approximately 60% . The workforce reduction was substantially completed in July 2018. As of September 30, 2018 , we had 25 employees. On October 2, 2018 we filed a Certificate of Amendment of Amended and Restated Certificate of Incorporation with the Secretary of State of the state of Delaware to effect a 1-for-12 reverse stock split of our issued and outstanding common stock. The reverse stock split became effective at 5:00 p.m. Eastern Time on October 3, 2018 and our common stock began trading on a split-adjusted basis on The Nasdaq Global Market on October 4, 2018. The accompanying condensed financial statements and notes thereto give retrospective effect to the reverse stock split for all periods presented. All issued and outstanding common stock, options exercisable for common stock, restricted stock units, and per share amounts contained in our condensed financial statements have been retrospectively adjusted. Liquidity The accompanying financial statements have been prepared on a basis which assumes we are a going concern, and does not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from any uncertainty related to our ability to continue as a going concern. Through the date of the issuance of these financial statements, we have principally been financed through proceeds received from the sale of our common stock and other equity securities, debt financings, up-front payments and milestones received from collaboration agreements. As of September 30, 2018, we had approximately $20.5 million of cash, cash equivalents and short-term investments. Based on our operating plans, we believe our cash, cash equivalents and short-term investments may not be sufficient to fund our operations for the period one year following the issuance of these financial statements. As a result, there is substantial doubt about our ability to continue as a going concern. All amounts due under the Term Loan (see note 5) have been classified as a current liability as of September 30, 2018 and December 31, 2017 due to the considerations discussed above and the assessment that the material adverse change clause under the Term Loan is not within our control. We have not been notified of an event of default by the Lender as of the date of the filing of this Form 10-Q. We intend to seek additional capital through equity and/or debt financings, collaborative or other funding arrangements with partners or through other sources of financing. Should we seek additional financing from outside sources, we may not be able to raise such financing on terms acceptable to us, or at all. If we are unable to raise additional capital when required or on acceptable terms, we may be required to scale back or discontinue the advancement of product candidates, reduce headcount, file for bankruptcy, reorganize, merge with another entity, or cease operations. If we become unable to continue as a going concern, we may have to liquidate our assets, and might realize significantly less than the values at which they are carried on our financial statements, and stockholders may lose all or part of their investment in our common stock. 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. Effective January 1, 2018, we adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition (“Topic 605”). All periods prior to the adoption date of Topic 606 have not been restated to reflect the impact of the adoption of Topic 606, but are accounted for and presented under Topic 605. The following paragraphs in this section describe our revenue recognition accounting polices under Topic 606 upon adoption on January 1, 2018. Refer to Note 1 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 for revenue recognition accounting policies under Topic 605. We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligation(s). At contract inception, we assess the goods or services promised within each contract, assess whether each promised good or service is distinct and identify those that are performance obligations. We recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements We enter into collaborative arrangements with partners that typically include payment to us of one of more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as contract liabilities and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation(s). The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. We evaluate each performance obligation to determine if it can be satisfied at a point in time, or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, we use judgment to assess the nature of the combined performance obligation to determine whether it is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of an arrangement, the associated milestone value is included in the transaction price. Milestone payments that are contingent upon the achievement of events that are uncertain or not controllable, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received, and therefore not included in the transaction price. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, we evaluate the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, we have not recognized any royalty revenue resulting from any of our collaborative arrangements. 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 restricted stock units by determining the fair value of each restricted stock unit based on the closing market price of our common stock on the date of grant. We recognize stock-based compensation expense using the accelerated multiple-option approach over the requisite service periods of the awards. 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. 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 expense the cost of materials when used. We periodically review these capitalized materials for continued alternative future use and write down the asset to its net realizable value in the period in which it is identified. Recent Accounting Pronouncements As disclosed above, effective January 1, 2018, we adopted Topic 606. Since ASU 2014-09 was issued, several additional ASUs have been issued and incorporated within Topic 606 to clarify various elements of the guidance. As part of our adoption efforts, we have completed the assessment of our collaboration and license agreements under Topic 606. We adopted Topic 606 in the first quarter of 2018 using the modified retrospective method which consists of applying and recognizing the cumulative effect of Topic 606 at the date of initial application and providing certain additional disclosures as defined per Topic 606. On January 1, 2018, we recorded a cumulative adjustment to decrease deferred revenue and accumulated deficit by approximately $1.8 million to reflect the impact of the adoption of Topic 606. The cumulative adjustment relates primarily to our agreement with Sanofi which is described further in Note 7. Below is a summary of the affected line items of the condensed balance sheets upon adoption of Topic 606 (in thousands): Balance at December 31, 2017 Adjustments due to Topic 606 Balance at January 1, 2018 Balance Sheet Deferred revenue (contract liabilities), non-current 1,921 (1,844 ) 77 Accumulated deficit (345,858 ) 1,844 (344,014 ) There is no difference between what our revenue would have been in the three and nine months ended September 30, 2018 , reported under Topic 606 or Topic 605. 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 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. The adoption of this guidance had no impact 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. Since ASU 2016-02 was issued, several additional ASUs have been issued to clarify various elements of the guidance. 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 in the process of determining the impact the adoption will have on our financial statements and expect significant changes to the recognition of right-of-use assets and liabilities associated with our operating leases. 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 annual reporting periods. The adoption of this guidance had no impact on our financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , which requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual reporting periods. The adoption of this guidance will have no impact on our financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting , which provides clarity and guidance around which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual reporting periods. The adoption of this guidance had no impact on our financial statements and will continue to have no impact on our financial statements unless we have modification accounting in accordance with Topic 718. In December 2017, The Tax Cuts and Jobs Act (the "Act") was signed into law and amended the Internal Revenue Code, or IRC, to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. Due to uncertainties which currently exist in the interpretation of the provisions of the Act regarding IRC Section 162(m), as of September 30, 2018, we have not completed our evaluation of the potential impacts of IRC Section 162(m) as amended by the Act on our financial statements. In March 2018, the FASB issued ASU No. 2018-05, Income taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , which provides guidance regarding the recording of tax impacts where uncertainty exists, in the period of adoption of the Act. To the extent that a company’s accounting for certain income tax effects of the Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate to be included in the condensed financial statements. If a company cannot determine a provisional estimate to be included in the condensed financial statements, it should continue to apply ASC 740 on the basis of the provision of the tax laws that were in effect immediately before the enactment of the Act. We have provisionally determined that there is no deferred tax benefit or expense with respect to the re-measurement of certain deferred tax assets and liabilities due to the full valuation allowance against net deferred tax assets. Additional analysis of the law and the impact to the company will be performed and any impact will be recorded in the respective quarter. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting , which aligns the measurement and classification guidance for share-based payment to non-employees with the guidance for share-based payments to employees. Under the new guidance, the measurement period for equity-classified non-employee awards will be fixed at the grant date. This update is effective for annual periods beginning after December 15, 2018, and interim periods within those periods and early adoption is permitted. The adoption of this guidance will have no impact on our financial statements. In August 2018, the FASB issues ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which updates and modifies the disclosure requirements on fair value measurements in Topic 820, primarily in relation to Level 3 fair value measurements. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods. Early adoption 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, 2018
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 zero and 575,256 shares attributable to common stock options and restricted stock units ("RSUs") for the three and nine months ended September 30, 2018 , respectively, compared to 106,597 and 210,816 shares attributable to common stock options for the three and nine months ended September 30, 2017 , respectively.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Debt Securities, Available-for-sale [Abstract]
Investments	Investments We invest our excess cash primarily in debt instruments of financial institutions, corporations, U.S. government-sponsored agencies and the U.S. Treasury. We generally hold our investments to maturity and do not sell our investments before we have recovered our amortized cost basis. 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, 2018 Certificates of deposit 1 or less $ 2,440 $ — $ — $ 2,440 U.S. Treasury securities 1 or less 3,999 1 (7 ) 3,993 Total $ 6,439 $ 1 $ (7 ) $ 6,433 Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of December 31, 2017 Corporate debt securities 1 or less $ 32,922 $ — $ (55 ) $ 32,867 Certificates of deposit 1 or less 8,216 — — 8,216 U.S. Treasury securities 1 or less 3,996 — (18 ) 3,978 Debt securities of U.S. government-sponsored agencies 1 or less 1,498 — (4 ) 1,494 Total $ 46,632 $ — $ (77 ) $ 46,555

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
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, 2018 and December 31, 2017 (in thousands): Fair value as of September 30, 2018 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 13,631 $ 13,631 $ — $ — Certificates of deposit 2,440 — 2,440 — U.S. treasury securities 3,993 — 3,993 — $ 20,064 $ 13,631 $ 6,433 $ — Fair value as of December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 10,847 $ 10,847 $ — $ — Corporate debt securities 32,867 — 32,867 — Certificates of deposit 8,216 — 8,216 — U.S. treasury securities 3,978 — 3,978 — Debt securities of U.S. government-sponsored agencies 1,494 — 1,494 — $ 57,402 $ 10,847 $ 46,555 $ — 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.

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2018
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 ” or sometimes referred to as the “ Lender ” ), 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 ” ). On June 22, 2016, we received $20.0 million in proceeds from the Term A Loan, net of debt issuance costs. The ability to borrow on the Term B Loan expired on March 31, 2017, and no amounts were borrowed under the Term B Loan. We refer to all amounts outstanding under the Loan Agreement as the Term Loan. The outstanding Term Loan will mature on June 1, 2020 (the “Maturity Date”) and bears 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% . Under the original Loan Agreement, we were required to make interest-only payments through June 1, 2018, followed by 24 equal monthly payments of principal and unpaid accrued interest. In March 2018, we and Oxford entered into an amendment to our Loan Agreement, providing for the modification of the loan amortization period from a 24 -month period commencing on July 1, 2018 to a 15 -month period commencing on April 1, 2019, subject to our receipt, following the date of the amendment, of unrestricted net cash proceeds of not less than $30.0 million on or prior to June 30, 2018. The ability to modify the loan amortization period under this amendment to the Loan Agreement expired on June 30, 2018, as we did not receive unrestricted net cash proceeds of not less than $30.0 million on or prior to June 30, 2018. In August 2018, we and Oxford entered into an additional amendment to our Loan Agreement, providing for a modification of the loan amortization period. Under the terms of the amendment, principal amortization and repayment was deferred between August 2018 through October 2018, and during this period, we were required to make payments of interest-only. Amortization payments will recommence in November 2018. In addition, the amendment contained a minimum cash reserve covenant, whereby we will be required to maintain aggregate cash reserves of not less than 110% of the principal balance of the Term Loan that would be outstanding on such date that our then-held cash reserves would first be completely exhausted based on certain assumptions specified in the amendment. There were no changes to the maturity date of the Term Loan, which is June 2020. Pursuant to the amendment, we granted the Lender a security interest in our intellectual property as additional collateral for the repayment of the Term Loan. We have the option to prepay all, but not less than all, of the borrowed amount, provided that we will be obligated to pay a prepayment fee equal to (i) 2% of the outstanding principal balance of the Term Loan if prepayment is made prior to the second anniversary of the funding date of the Term Loan, or (ii) 1% of the 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 the Term Loan, or (iii) the prepayment of the Term Loan. We may use the proceeds from the Term Loan 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 and certain assets under capital lease obligations. We have also agreed not to encumber our intellectual property assets, except as permitted by the Loan Agreement. The Loan Agreement includes customary events of default, including instances of a material adverse change in our operations, that may require prepayment of the outstanding Term Loan. All amounts due under the Term Loan have been classified as a current liability as of September 30, 2018 due to the considerations discussed in Note 1 and the assessment that the material adverse change clause under the Term Loan is not within our control. We have not been notified of an event of default by the Lender as of the date of the filing of this Form 10-Q. As of September 30, 2018 , we had a net liability of $19.1 million outstanding under the Term Loan. In connection with the Term Loan, the debt issuance costs have been recorded as a debt discount in our consolidated balance sheets, which are being accreted to interest expense over the life of the Term Loan using an effective interest rate of 8.98% . The exit fee is being accrued over the life of the Term Loan through interest expense. As of September 30, 2018 , we were in compliance with all covenants under the Loan Agreement. As of September 30, 2018, future principal payments for the Term Loan due under the Loan Agreement are as follows (in thousands): 2018 $ 1,917 2019 11,500 2020 5,750 $ 19,167

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
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, 2018 (in thousands): Common stock options outstanding 1,134 RSUs outstanding 66 Common stock available for future grant under 2012 Equity Incentive Plan 61 Common stock available for future grant under 2015 Inducement Plan 3 Employee Stock Purchase Plan 155 Total common shares reserved for future issuance 1,419 The following table summarizes our stock option and RSU activity (together Stock Awards) under all equity incentive plans for the nine months ended September 30, 2018 (shares in thousands): Number of options Weighted average exercise price Number of RSUs Weighted average grant date fair value Stock Awards outstanding at December 31, 2017 887 $ 53.24 35 $ 10.68 Granted 603 $ 11.70 102 $ 3.88 Exercised (options) or Vested (RSUs) (1 ) $ 4.56 (57 ) $ 6.25 Canceled/forfeited/expired (355 ) $ 58.59 (8 ) $ 7.57 Stock Awards outstanding at September 30, 2018 1,134 72 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 2018 2017 2018 2017 Stock options Risk-free interest rate 2.9 % 1.9 % 2.7 % 2.0 % Volatility 92.0 % 89.5 % 87.8 % 89.4 % Dividend yield — — — — Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — — 2.7 % 2.1 % Volatility — — 87.4 % 89.9 % Dividend yield — — — — Expected term (years) 0.0 0.0 5.7 5.6 Employee stock purchase plan shares Risk-free interest rate 2.0 % 1.0 % 1.8 % 0.8 % Volatility 99.9 % 104.5 % 91.7 % 110.7 % 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 2018 2017 2018 2017 Research and development $ 491 $ 653 $ 1,745 $ 2,411 Research and development-restructuring related adjustments 31 — 31 (1,399 ) General and administrative 883 631 2,613 2,840 General and administrative-restructuring related adjustments (15 ) — (15 ) 2,679 Total $ 1,390 $ 1,284 $ 4,374 $ 6,531

Strategic Alliances and Collabo

Strategic Alliances and Collaborations	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Strategic Alliances and Collaborations	Strategic Alliances and Collaborations Revenue recognized from our strategic alliances and collaborations was less than $0.1 million for each of the three and nine months ended September 30, 2018 and 2017 . 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 was deferred as of December 31, 2017 and recorded as an adjustment to accumulated deficit upon our adoption of ASC 606 on January 1, 2018. 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 has 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 (“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. 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, 2018 , contract liabilities associated with the Purchase Agreement and the 2014 Sanofi Amendment was $0.1 million , which we are expecting to recognize over the remaining estimated period of performance of approximately one year. 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.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
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 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 engaged Sanofi Deutschland to manufacture RG-012 drug product and perform stability studies on our behalf. Expenses incurred under the agreement for services performed or out-of-pocket expenses were less than $0.1 million for each of the three and nine months ended September 30, 2018 and 2017 .

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Reverse Stock Split On October 2, 2018, we filed a Certificate of Amendment of Amended and Restated Certificate of Incorporation with the Secretary of State of the state of Delaware to effect a 1-for-12 reverse stock split of our issued and outstanding common stock. The primary purpose of the reverse stock split was to raise the per share trading price of our common stock to seek to maintain the listing of our common stock on The Nasdaq Global Market. At the effective time of the reverse stock split at 5:00 p.m. on October 3, 2018, each 12 shares of our issued and outstanding common stock were automatically combined and converted into one issued and outstanding share of common stock. All of our stock options and RSUs outstanding immediately prior to the reverse stock split were proportionately adjusted. All issued and outstanding common stock, options exercisable for common stock, restricted stock units, and per share amounts contained in our condensed financial statements have been retrospectively adjusted. Tender Offer On October 15, 2018, we filed a tender offer statement on Schedule TO with the Securities and Exchange Commission related to an offer by us to certain eligible optionholders, subject to specified conditions, to exchange some or all of their outstanding options to purchase shares of our common stock for new RSUs (the "Exchange Offer"). The Exchange Offer will expire at 5:00 p.m., U.S. Pacific Time, on November 11, 2018, unless extended. An option holder will be eligible to exchange their options (an “Eligible Holder”) if: • on the date the Exchange Offer commences, either an optionholder is employed by us (each, an “Employee”) or is a non-employee member (each, a “Non-Employee Director”) of our board of directors and has not been notified by us that such optionholder’s employment or service relationship with us is being terminated; and • such optionholder continues to be an Employee or serve as a Non-Employee Director and has not submitted a notice of resignation or received a notice of termination, as of the first business day following the Expiration Time (as defined in the Exchange Offer). An option will be eligible for exchange (an “Eligible Option”) if it: • is held by an Eligible Holder; • has an exercise price equal to or greater than $4.56 (and an exercise price greater than the closing price of our common stock on the last business day before the Expiration Time); and • was granted under our 2009 Equity Incentive Plan, 2012 Equity Incentive Plan or 2015 Inducement Plan. The exchange ratio for each Eligible Option will be determined using the Black-Scholes option pricing model and will be based on, among other things, the fair market value of a share of our common stock, the volatility of our common stock, U.S. treasury rates, the exercise prices of the Eligible Options, the remaining terms of the Eligible Options and the term of the new RSUs. For purposes of determining the fair value of Eligible Options, the fair market value of a share of our common stock will be determined based on the trailing 20-day volume weighted average price (the “20-Day VWAP”). The 20-Day VWAP represents the simple arithmetic average of the daily VWAPs over the 20 consecutive trading days beginning on October 15, 2018 and ending on the last business day prior to the Expiration Time. For purposes of determining the fair value of the new RSUs, the fair market value of a share of our common stock will be determined based on the closing trading price of a share of our common stock on Nasdaq on the last business day prior to the Expiration Time. In no event will an Eligible Optionholder be eligible to receive more new RSUs than the number of shares underlying the number of Eligible Options. The foregoing is only a summary of the Exchange Offer, does not purport to be complete and is qualified in its entirety by reference to the full text of the Schedule TO, which was filed with the Securities and Exchange Commission on October 15, 2018. First Amendment to Second Amended and Restated Collaboration and License Agreement On November 5, 2018, we entered into an amendment to the 2014 Sanofi Amendment with Sanofi to modify the parties’ rights and obligations with respect to our miR-21 programs, including our RG-012 program (the “2018 Sanofi Amendment”). Under the terms of the 2018 Sanofi Amendment, we have granted Sanofi a worldwide, royalty-free, fee-bearing, exclusive license, with the right to grant sublicenses, under our know-how and patents to develop and commercialize miR-21 compounds and products for all indications, including Alport Syndrome. Sanofi will control and will assume all responsibilities and obligations for developing and commercializing each of our miR-21 programs, including our obligations regarding the administration and expense of clinical trials and all other costs, including in-license royalties and other in-license payments, related to our miR-21 programs. Under the terms of the 2018 Sanofi Amendment, we have assigned to Sanofi certain agreements and all materials directed to miR-21 or to any miR-21 compound or product and are required to provide reasonable technical assistance to Sanofi for a period of 24 months after the date of the 2018 Sanofi Amendment. Under the terms of the 2018 Sanofi Amendment, we are eligible to receive approximately $6.8 million in upfront payments and a payment for miR-21 program-related materials (collectively, the “Upfront Amendment Payments”). We are also eligible to receive up to $40.0 million in development milestone payments. In addition, Sanofi has agreed to reimburse us for certain out-of-pocket transition activities and assume our upstream license royalty obligations. We and Sanofi also agreed to a general release of claims against each other for any claims that arose at any time prior to the date of the 2018 Sanofi Amendment, or that thereafter could arise based on anything that occurred prior to the date of the 2018 Sanofi Amendment. Fourth Amendment to Loan and Security Agreement On November 5, 2018 and in connection with the 2018 Sanofi Amendment we entered into a fourth amendment to the Term Loan with the Lender (the "Fourth Amendment"). Under the terms of the Fourth Amendment, the Lender has consented to the 2018 Sanofi Amendment and our license, assignment and transfer to Sanofi of certain of our intellectual property, as required to be delivered to Sanofi under the 2018 Sanofi Amendment (the “Assigned Assets”), which previously served as collateral under the loan and security agreement, and has released its liens in the Assigned Assets, provided that the Lender will continue to have liens on all proceeds received by us pursuant to the Sanofi License. Under the terms of the Fourth Amendment, we now have the option to prepay part of the Term Loan at any time and in any amount after 10 days’ prior written notice. We are also required to prepay part of the Term Loan with 25% of certain payments we receive under the 2018 Sanofi Amendment, which payments consist of the Upfront Amendment Payments and the first development milestone payment in the amount of $10.0 million . We will be required to pay the applicable 5.5% final payment fee related to each such 2018 Sanofi Amendment prepayment. Under the Fourth Amendment, we are required to maintain cash in a collateral account controlled by the Lender of (i) $10.0 million , if we have not received net proceeds of at least $15.0 million from (a) the issuance and sale of our unsecured subordinated convertible debt and/or equity securities or (b) upfront or milestone payments in connection with a joint venture, collaboration or other partnering transaction, other than pursuant to the Sanofi License (the receipt of such net proceeds, a “Capital Event”), or (ii) $5.0 million if a Capital Event has occurred. The maturity date of the Term Loan remains unchanged and the Term Loan is required to be paid in full on June 1, 2020.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
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, 2017 , 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. Effective January 1, 2018, we adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition (“Topic 605”). All periods prior to the adoption date of Topic 606 have not been restated to reflect the impact of the adoption of Topic 606, but are accounted for and presented under Topic 605. The following paragraphs in this section describe our revenue recognition accounting polices under Topic 606 upon adoption on January 1, 2018. Refer to Note 1 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 for revenue recognition accounting policies under Topic 605. We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligation(s). At contract inception, we assess the goods or services promised within each contract, assess whether each promised good or service is distinct and identify those that are performance obligations. We recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements We enter into collaborative arrangements with partners that typically include payment to us of one of more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as contract liabilities and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation(s). The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. We evaluate each performance obligation to determine if it can be satisfied at a point in time, or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, we use judgment to assess the nature of the combined performance obligation to determine whether it is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of an arrangement, the associated milestone value is included in the transaction price. Milestone payments that are contingent upon the achievement of events that are uncertain or not controllable, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received, and therefore not included in the transaction price. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, we evaluate the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, we have not recognized any royalty revenue resulting from any of our collaborative arrangements.
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 restricted stock units by determining the fair value of each restricted stock unit based on the closing market price of our common stock on the date of grant. We recognize stock-based compensation expense using the accelerated multiple-option approach over the requisite service periods of the awards.
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.
Prepaid Materials	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 expense the cost of materials when used. We periodically review these capitalized materials for continued alternative future use and write down the asset to its net realizable value in the period in which it is identified.
Recent Accounting Pronouncements	Recent Accounting Pronouncements As disclosed above, effective January 1, 2018, we adopted Topic 606. Since ASU 2014-09 was issued, several additional ASUs have been issued and incorporated within Topic 606 to clarify various elements of the guidance. As part of our adoption efforts, we have completed the assessment of our collaboration and license agreements under Topic 606. We adopted Topic 606 in the first quarter of 2018 using the modified retrospective method which consists of applying and recognizing the cumulative effect of Topic 606 at the date of initial application and providing certain additional disclosures as defined per Topic 606. On January 1, 2018, we recorded a cumulative adjustment to decrease deferred revenue and accumulated deficit by approximately $1.8 million to reflect the impact of the adoption of Topic 606. The cumulative adjustment relates primarily to our agreement with Sanofi which is described further in Note 7. Below is a summary of the affected line items of the condensed balance sheets upon adoption of Topic 606 (in thousands): Balance at December 31, 2017 Adjustments due to Topic 606 Balance at January 1, 2018 Balance Sheet Deferred revenue (contract liabilities), non-current 1,921 (1,844 ) 77 Accumulated deficit (345,858 ) 1,844 (344,014 ) There is no difference between what our revenue would have been in the three and nine months ended September 30, 2018 , reported under Topic 606 or Topic 605. 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 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. The adoption of this guidance had no impact 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. Since ASU 2016-02 was issued, several additional ASUs have been issued to clarify various elements of the guidance. 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 in the process of determining the impact the adoption will have on our financial statements and expect significant changes to the recognition of right-of-use assets and liabilities associated with our operating leases. 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 annual reporting periods. The adoption of this guidance had no impact on our financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , which requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual reporting periods. The adoption of this guidance will have no impact on our financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting , which provides clarity and guidance around which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual reporting periods. The adoption of this guidance had no impact on our financial statements and will continue to have no impact on our financial statements unless we have modification accounting in accordance with Topic 718. In December 2017, The Tax Cuts and Jobs Act (the "Act") was signed into law and amended the Internal Revenue Code, or IRC, to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. Due to uncertainties which currently exist in the interpretation of the provisions of the Act regarding IRC Section 162(m), as of September 30, 2018, we have not completed our evaluation of the potential impacts of IRC Section 162(m) as amended by the Act on our financial statements. In March 2018, the FASB issued ASU No. 2018-05, Income taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , which provides guidance regarding the recording of tax impacts where uncertainty exists, in the period of adoption of the Act. To the extent that a company’s accounting for certain income tax effects of the Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate to be included in the condensed financial statements. If a company cannot determine a provisional estimate to be included in the condensed financial statements, it should continue to apply ASC 740 on the basis of the provision of the tax laws that were in effect immediately before the enactment of the Act. We have provisionally determined that there is no deferred tax benefit or expense with respect to the re-measurement of certain deferred tax assets and liabilities due to the full valuation allowance against net deferred tax assets. Additional analysis of the law and the impact to the company will be performed and any impact will be recorded in the respective quarter. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting , which aligns the measurement and classification guidance for share-based payment to non-employees with the guidance for share-based payments to employees. Under the new guidance, the measurement period for equity-classified non-employee awards will be fixed at the grant date. This update is effective for annual periods beginning after December 15, 2018, and interim periods within those periods and early adoption is permitted. The adoption of this guidance will have no impact on our financial statements. In August 2018, the FASB issues ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which updates and modifies the disclosure requirements on fair value measurements in Topic 820, primarily in relation to Level 3 fair value measurements. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods. Early adoption is permitted. The adoption of this guidance will have no impact on our financial statements.
Fair Value Measurement	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.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Below is a summary of the affected line items of the condensed balance sheets upon adoption of Topic 606 (in thousands): Balance at December 31, 2017 Adjustments due to Topic 606 Balance at January 1, 2018 Balance Sheet Deferred revenue (contract liabilities), non-current 1,921 (1,844 ) 77 Accumulated deficit (345,858 ) 1,844 (344,014 )

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Securities, Available-for-sale [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, 2018 Certificates of deposit 1 or less $ 2,440 $ — $ — $ 2,440 U.S. Treasury securities 1 or less 3,999 1 (7 ) 3,993 Total $ 6,439 $ 1 $ (7 ) $ 6,433 Maturity (in years) Amortized cost Unrealized Estimated fair value Gains Losses As of December 31, 2017 Corporate debt securities 1 or less $ 32,922 $ — $ (55 ) $ 32,867 Certificates of deposit 1 or less 8,216 — — 8,216 U.S. Treasury securities 1 or less 3,996 — (18 ) 3,978 Debt securities of U.S. government-sponsored agencies 1 or less 1,498 — (4 ) 1,494 Total $ 46,632 $ — $ (77 ) $ 46,555

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 and December 31, 2017 (in thousands): Fair value as of September 30, 2018 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 13,631 $ 13,631 $ — $ — Certificates of deposit 2,440 — 2,440 — U.S. treasury securities 3,993 — 3,993 — $ 20,064 $ 13,631 $ 6,433 $ — Fair value as of December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Cash equivalents $ 10,847 $ 10,847 $ — $ — Corporate debt securities 32,867 — 32,867 — Certificates of deposit 8,216 — 8,216 — U.S. treasury securities 3,978 — 3,978 — Debt securities of U.S. government-sponsored agencies 1,494 — 1,494 — $ 57,402 $ 10,847 $ 46,555 $ —

Term Loan (Tables)

Term Loan (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Term Loan	As of September 30, 2018, future principal payments for the Term Loan due under the Loan Agreement are as follows (in thousands): 2018 $ 1,917 2019 11,500 2020 5,750 $ 19,167

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 (in thousands): Common stock options outstanding 1,134 RSUs outstanding 66 Common stock available for future grant under 2012 Equity Incentive Plan 61 Common stock available for future grant under 2015 Inducement Plan 3 Employee Stock Purchase Plan 155 Total common shares reserved for future issuance 1,419
Stock Option Activity	The following table summarizes our stock option and RSU activity (together Stock Awards) under all equity incentive plans for the nine months ended September 30, 2018 (shares in thousands): Number of options Weighted average exercise price Number of RSUs Weighted average grant date fair value Stock Awards outstanding at December 31, 2017 887 $ 53.24 35 $ 10.68 Granted 603 $ 11.70 102 $ 3.88 Exercised (options) or Vested (RSUs) (1 ) $ 4.56 (57 ) $ 6.25 Canceled/forfeited/expired (355 ) $ 58.59 (8 ) $ 7.57 Stock Awards outstanding at September 30, 2018 1,134 72
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 2018 2017 2018 2017 Stock options Risk-free interest rate 2.9 % 1.9 % 2.7 % 2.0 % Volatility 92.0 % 89.5 % 87.8 % 89.4 % Dividend yield — — — — Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — — 2.7 % 2.1 % Volatility — — 87.4 % 89.9 % Dividend yield — — — — Expected term (years) 0.0 0.0 5.7 5.6 Employee stock purchase plan shares Risk-free interest rate 2.0 % 1.0 % 1.8 % 0.8 % Volatility 99.9 % 104.5 % 91.7 % 110.7 % 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 2018 2017 2018 2017 Research and development $ 491 $ 653 $ 1,745 $ 2,411 Research and development-restructuring related adjustments 31 — 31 (1,399 ) General and administrative 883 631 2,613 2,840 General and administrative-restructuring related adjustments (15 ) — (15 ) 2,679 Total $ 1,390 $ 1,284 $ 4,374 $ 6,531

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	1 Months Ended
	Jul. 31, 2018	May 31, 2017employee	Sep. 30, 2018USD ($)employee	Jan. 01, 2018USD ($)
Accounting Policies [Abstract]
Reduction of workforce	60.00%	30.00%
Number of employees | employee		65	25
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents and marketable securities			$ 20.5
AOCI Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption				$ (1.8)

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies (Effect of New Accounting Principle) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue (contract liabilities), non-current		$ 77
Accumulated deficit	$ (384,161)	(344,014)	$ (345,858)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue (contract liabilities), non-current			1,921
Accumulated deficit			$ (345,858)
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue (contract liabilities), non-current		(1,844)
Accumulated deficit		$ 1,844

Net Loss Per Share (Detail)

Net Loss Per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Potentially dilutive securities not included in calculation of diluted net loss per share (in shares)	0	106,597	575,256	210,816

Investments (Summary of Short-T

Investments (Summary of Short-Term Investments) (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 6,439	$ 46,632
Unrealized Gains	1	0
Unrealized Losses	(7)	(77)
Estimated fair value	$ 6,433	$ 46,555
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Maturity (or less) (in years)		1 year
Amortized cost		$ 32,922
Unrealized Gains		0
Unrealized Losses		(55)
Estimated fair value		$ 32,867
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Maturity (or less) (in years)	1 year	1 year
Amortized cost	$ 2,440	$ 8,216
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated fair value	$ 2,440	$ 8,216
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Maturity (or less) (in years)	1 year	1 year
Amortized cost	$ 3,999	$ 3,996
Unrealized Gains	1	0
Unrealized Losses	(7)	(18)
Estimated fair value	$ 3,993	$ 3,978
Debt securities of U.S. government-sponsored agencies
Debt Securities, Available-for-sale [Line Items]
Maturity (or less) (in years)		1 year
Amortized cost		$ 1,498
Unrealized Gains		0
Unrealized Losses		(4)
Estimated fair value		$ 1,494

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 20,064	$ 57,402
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	13,631	10,847
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	6,433	46,555
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		32,867
Corporate debt securities | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		0
Corporate debt securities | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		32,867
Corporate debt securities | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		0
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,440	8,216
Certificates of deposit | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Certificates of deposit | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,440	8,216
Certificates of deposit | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	3,993	3,978
U.S. Treasury securities | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
U.S. Treasury securities | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	3,993	3,978
U.S. Treasury securities | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Debt securities of U.S. government-sponsored agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		1,494
Debt securities of U.S. government-sponsored agencies | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		0
Debt securities of U.S. government-sponsored agencies | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		1,494
Debt securities of U.S. government-sponsored agencies | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis		0
Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	13,631	10,847
Cash equivalents | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	13,631	10,847
Cash equivalents | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Cash equivalents | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 0	$ 0

Term Loan (Details)

Term Loan (Details)	Jun. 22, 2016USD ($)	Jun. 17, 2016USD ($)loan	Mar. 31, 2018	Sep. 30, 2018USD ($)
Debt Financing Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 30,000,000
Number of term loans | loan		2
Stated interest rate, percentage		8.51%
Period for principal and interest payments		24 months
Amended period for principal and interest payments			15 months
Unrestricted cash raised target				$ 30,000,000
Prepayment fee, option one				2.00%
Prepayment fee, option two				1.00%
Debt extinguishment fee				5.50%
Term loan, less debt issuance costs				$ 19,100,000
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				$ 19,167,000
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) - Debt Financing Agreement Tranche A $ in Thousands	Sep. 30, 2018USD ($)
Debt Instrument [Line Items]
Future Repayments of Principal, 2018	$ 1,917
Future Repayments of Principal, 2019	11,500
Future Repayments of Principal, 2020	5,750
Long-term Debt	$ 19,167

Stockholders' Equity (Common St

Stockholders' Equity (Common Stock Reserved for Future Issuance) (Detail) shares in Thousands	Sep. 30, 2018shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock options outstanding	1,134
Total common shares reserved for future issuance	1,419
Common stock available for future grant under 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding	66
Common stock available for future grant	61
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	3
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant	155

Stockholders' Equity (Stock Opt

Stockholders' Equity (Stock Option and RSU Activity) (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Number of options
Number of options, ending outstanding number (in shares)	1,134
Stock options
Number of options
Number of options, beginning outstanding number (in shares)	887
Number of options, Granted (in shares)	603
Number of options, Exercised (in shares)	(1)
Number of options, Canceled/forfeited/expired (in shares)	(355)
Number of options, ending outstanding number (in shares)	1,134
Weighted average exercise price
Weighted average exercise price, beginning balance (in dollars per share) | $ / shares	$ 53.24
Weighted average exercise price, Granted (in dollars per share) | $ / shares	11.70
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	4.56
Weighted average exercise price, Canceled/forfeited/expired (in dollars per share) | $ / shares	$ 58.59
Restricted Stock Units (RSUs)
Number of RSUs
Shares outstanding (in shares)	35
Shares granted (in shares)	102
Shares vested in period (in shares)	(57)
Shares canceled in period (in shares)	(8)
Shares outstanding (in shares)	72
Weighted average grant date fair value
Beginning balance (usd per share) | $ / shares	$ 10.68
Granted (usd per share) | $ / shares	3.88
Exercised (usd per share) | $ / shares	6.25
Canceled/forfeited/expired (usd per share) | $ / shares	$ 7.57

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Stock Purchase Plan
Weighted average assumptions
Risk-free interest rate	2.00%	1.00%	1.80%	0.80%
Volatility	99.90%	104.50%	91.70%	110.70%
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	2.90%	1.90%	2.70%	2.00%
Volatility	92.00%	89.50%	87.80%	89.40%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 years 29 days	6 years 1 month 6 days	6 years 29 days	6 years 1 month 6 days
Performance stock options
Weighted average assumptions
Risk-free interest rate	0.00%	0.00%	2.70%	2.10%
Volatility	0.00%	0.00%	87.40%	89.90%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	0 years	0 years	5 years 7 months 25 days	5 years 7 months 6 days

Stockholders' Equity (Stock-Bas

Stockholders' Equity (Stock-Based Compensation Expense Allocation) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 1,390	$ 1,284	$ 4,374	$ 6,531
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	491	653	1,745	2,411
Research and development-restructuring related adjustments
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	31	0	31	(1,399)
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	883	631	2,613	2,840
General and administrative-restructuring related adjustments
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ (15)	$ 0	$ (15)	$ 2,679

Strategic Alliances and Colla_2

Strategic Alliances and Collaborations (Detail)	1 Months Ended			3 Months Ended		8 Months Ended	9 Months Ended
	Feb. 28, 2014USD ($)$ / sharesshares	Jul. 31, 2013USD ($)	Jul. 31, 2012target	Sep. 30, 2018USD ($)shares	Sep. 30, 2017USD ($)	Jan. 31, 2014USD ($)	Sep. 30, 2018USD ($)shares	Sep. 30, 2017USD ($)	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)shares
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues (less than)				$ 18,000	$ 18,000		$ 54,000	$ 54,000
Common stock, shares issued (shares) | shares				8,750,343			8,750,343			8,662,435
Common stock value				$ 9,000			$ 9,000			$ 9,000
Deferred revenue									$ 77,000
Revenue under strategic alliances and collaborations
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues (less than)				100,000	$ 100,000		$ 100,000	$ 100,000
Sanofi
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of collaborative areas granted | target			4
Deferred revenue	$ 400,000
Sanofi | Private Placement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Common stock, shares issued (shares) | shares	1,303,780
Price per share (in dollars per share) | $ / shares	$ 7.67
Common stock value	$ 10,000,000
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 | 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				100,000			$ 100,000
Deferred revenue recognition period							1 year
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
Sanofi | Clinical
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential revenue through milestone payments				$ 15,000,000			$ 15,000,000

Related Party Transactions (Det

Related Party Transactions (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Sanofi
Related Party Transaction [Line Items]
Expenses incurred for services performed or out-of-pocket expenses under the Sanofi agreement (less than)	$ 0.1	$ 0.1	$ 0.1	$ 0.1

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event	Oct. 02, 2018	Nov. 05, 2018USD ($)	Oct. 15, 2018$ / shares
Subsequent Event [Line Items]
Conversion ratio for reverse stock split	0.0833
Exercise price (usd per share) | $ / shares			$ 4.56
Term Loan
Subsequent Event [Line Items]
Potential revenue through milestone payments		$ 6,800,000
Fourth Amendment
Subsequent Event [Line Items]
Prepayment requirement of loan from license fees		25.00%
Potential revenue through milestone payments		$ 10,000,000
Payment fee		5.50%
Minimum cash, debt covenant		$ 10,000,000
Proceeds debt covenant, conditional minimum amount		15,000,000
Conditional amount, capital event, debt covenant		5,000,000
Development Milestones | Term Loan
Subsequent Event [Line Items]
Potential revenue through milestone payments		$ 40,000,000