Curis (CRIS) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	CRIS
Entity Registrant Name	CURIS INC
Entity Central Index Key	1,108,205
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		33,181,146

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 30,465	$ 38,288
Investments	9,955	21,944
Accounts receivable	2,505	3,073
Prepaid expenses and other current assets	776	989
Total current assets	43,701	64,294
Property and equipment, net	352	366
Long-term investment – restricted	153	153
Goodwill	8,982	8,982
Other assets	3	3
Total assets	53,191	73,798
Current Liabilities:
Accounts payable	4,275	5,423
Accrued liabilities	3,263	2,793
Current portion of long-term debt, net	6,965	5,886
Total current liabilities	14,503	14,102
Long-term debt, net	31,532	35,669
Other long-term liabilities	46	34
Total liabilities	46,081	49,805
Stockholders’ Equity:
Common stock, $0.01 par value—67,500,000 shares authorized, 33,181,146 shares issued and outstanding at June 30, 2018; 45,000,000 shares authorized, 33,075,949 shares issued and 32,831,380 shares outstanding at December 31, 2017	332	331
Additional paid-in capital	978,455	977,453
Treasury stock, at cost, 0 shares at June 30, 2018 and 244,569 shares at December 31, 2017	0	(1,524)
Accumulated deficit	(971,676)	(952,265)
Accumulated other comprehensive income	(1)	(2)
Total stockholders’ equity	7,110	23,993
Total liabilities and stockholders’ equity	$ 53,191	$ 73,798

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	225,000,000	225,000,000
Common stock, shares issued (in shares)	165,628,371	165,379,967
Common stock, shares outstanding (in shares)	165,628,371	164,157,121
Treasury stock, at cost (in shares)	0	1,222,846

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 2,358	$ 2,061	$ 4,826	$ 4,192
Costs and expenses:
Cost of royalty revenues	134	96	263	207
Research and development	6,451	11,255	14,717	24,795
General and administrative	3,633	3,819	7,614	7,351
Total costs and expenses	10,218	15,170	22,594	32,353
Loss from operations	(7,860)	(13,109)	(17,768)	(28,161)
Other (expense) income:
Other (expense) income	0	0	0	(104)
Interest income	189	138	375	208
Interest expense	(993)	(1,119)	(2,018)	(1,775)
Total other expense, net	(804)	(981)	(1,643)	(1,671)
Net loss	$ (8,664)	$ (14,090)	$ (19,411)	$ (29,832)
Net loss per common share (basic and diluted) (USD per share)	$ (0.26)	$ (0.49)	$ (0.59)	$ (1.04)
Weighted average common shares (basic and diluted) (shares)	33,135,391	28,757,341	33,094,772	28,580,829
Total comprehensive loss	$ (8,659)	$ (14,087)	$ (19,410)	$ (29,831)
Royalties
Revenues:
Total revenues	2,394	2,102	4,868	4,294
Research and development, net
Revenues:
Total revenues	$ (36)	$ (41)	$ (42)	$ (102)

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (19,411)	$ (29,832)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	99	113
Stock-based compensation expense	2,415	2,688
Amortization of debt issuance costs	16	128
Non-cash interest (income) expense on investments	(128)	(49)
Changes in operating assets and liabilities:
Accounts receivable	568	228
Prepaid expenses and other assets	213	299
Accounts payable and accrued and other liabilities	(674)	2,056
Total adjustments	2,509	5,463
Net cash used in operating activities	(16,902)	(24,369)
Cash flows from investing activities:
Purchase of investments	(20,932)	(27,476)
Sales and maturities of investments	33,050	21,608
Purchases of property and equipment	(77)	(126)
Net cash provided by/(used in) investing activities	12,041	(5,994)
Cash flows from financing activities:
Proceeds from issuance of common stock associated with offerings, net of issuance costs	0	6,214
Proceeds from issuance of common stock under the Company’s share-based compensation plans	112	890
Proceeds from credit agreement with HealthCare Royalty Partners, III, L.P.	0	45,000
Payment of debt issuance costs	0	(192)
Payment on termination of credit agreement with BioPharma-II	0	(18,303)
Payments on Curis Royalty’s debt	(3,074)	(2,607)
Net cash (used in)/provided by financing activities	(2,962)	31,002
Net (decrease)/increase in cash and cash equivalents	(7,823)	639
Cash and cash equivalents, beginning of period	38,288	26,038
Cash and cash equivalents, end of period	30,465	26,677
Non-cash items:
Property and equipment purchases in accounts payable	$ 8	$ 0

Nature of Business

Nature of Business	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Curis, Inc. is a biotechnology company seeking to develop and commercialize innovative drug candidates for the treatment of human cancers. As used throughout these consolidated financial statements, the term “the Company” refers to the business of Curis, Inc. and its wholly owned subsidiaries, except where the context otherwise requires, and the term “Curis” refers to Curis, Inc. The Company conducts its research and development programs both internally and through strategic collaborations. The Company’s clinical stage drug candidates are fimepinostat (CUDC-907), which is currently in clinical studies in patients with MYC-altered diffuse large B-cell lymphoma (DLBCL) and solid tumors; CA-170, which is currently undergoing testing in a Phase 1 study in patients with advanced solid tumors and lymphomas; and CA-4948, which is being tested in a Phase 1 trial in patients with advanced non-Hodgkin lymphomas, including those with myeloid differentiation primary response 88, or MYD88, alterations. The U.S. Food and Drug Administration, or FDA, granted fimepinostat Orphan Drug Designation in April 2015 and Fast Track Designation in May 2018 for the treatment of DLBCL. The Company’s pipeline also includes CA-327, which is a pre-Investigational New Drug (IND) stage oncology drug candidate. The Company continues work to enable the filing of an IND application with the U.S. FDA for clinical testing of CA-327 in 2018. The Company is party to a collaboration with F. Hoffmann-La Roche Ltd, or Roche, and Genentech Inc., or Genentech, a member of the Roche Group, under which Roche and Genentech are commercializing Erivedge, a first-in-class orally-administered small molecule Hedgehog signaling pathway inhibitor. Erivedge® (vismodegib) is approved for the treatment of advanced basal cell carcinoma, or BCC. In January 2015, and as amended in September 2016, the Company entered into a collaboration, option and license agreement focused on immuno-oncology and selected precision oncology targets with Aurigene Discovery Technologies Limited, or Aurigene. The collaboration with Aurigene is comprised of multiple programs, and Curis has the option to exclusively license each program, including data, intellectual property and compounds associated therewith, once a development candidate is nominated within such program. In October 2015, the Company exercised options to license two programs under this collaboration. The first licensed program is in the immuno-oncology field and the Company has named CA-170, an orally-available small molecule antagonist of two immune checkpoints, programmed death ligand-1 (PDL1) and V-domain Ig suppressor of T cell activation (VISTA), as the development candidate from this program. The second licensed program is in the precision oncology field and the Company has named CA-4948, an orally-available small molecule inhibitor of Interleukin-1 receptor-associated kinase 4 (IRAK4) as the development candidate. In October 2016, the Company exercised its option to license a third program in the collaboration, and designated CA-327, a distinct orally available small molecule antagonist of two immune checkpoints, PDL1 and T-cell immunoglobulin and mucin domain containing protein-3 (TIM3) as the development candidate from this program. In March 2018, the Company exercised its option to license a fourth program, which is an immuno-oncology program. The Company operates in a single reportable segment, which is the research and development of innovative cancer therapeutics. The Company expects that any products that are successfully developed and commercialized would be used in the healthcare industry and would be regulated in the United States by the FDA and in overseas markets by similar regulatory authorities. The Company is subject to risks common to companies in the biotechnology industry as well as risks that are specific to the Company’s business, including, but not limited to: the Company’s ability to advance and expand its research and development programs; the Company’s reliance on Aurigene to successfully discover and preclinically develop drug candidates under the parties’ collaboration agreement; the Company’s reliance on Roche and Genentech to successfully commercialize Erivedge in the approved indication of advanced BCC and to progress its clinical development in indications other than BCC; the Company’s ability to obtain adequate financing to fund its operations; the ability of the Company and its wholly-owned subsidiary, Curis Royalty, LLC, or Curis Royalty, to satisfy the terms of its credit agreement with HealthCare Royalty Partners III, L.P., a Delaware limited partnership managed by HealthCare Royalty Management, LLC, or HealthCare Royalty; the Company’s ability to obtain and maintain necessary intellectual property protection; development by the Company’s competitors of new or better technological innovations; the Company's dependence on key personnel; the Company’s ability to comply with regulatory requirements; the Company's ability to obtain and maintain applicable regulatory approvals and commercialize any approved product candidates and the Company’s ability to execute on its overall business strategies. The Company’s future operating results will largely depend on the progress of drug candidates currently in its development pipeline and the magnitude of payments that it may receive and make under its current and potential future collaborations. The results of the Company’s operations have varied and will likely continue to vary significantly from year to year and quarter to quarter and depend on a number of factors, including, but not limited to: the timing, outcome and cost of the Company’s preclinical studies and clinical trials for its drug candidates; Aurigene’s ability to successfully discover and develop preclinical programs under the Company’s collaboration with Aurigene, as well as the Company’s decision to exclusively license and further develop programs under this collaboration; Roche and Genentech’s ability to successfully commercialize Erivedge; and positive results in Roche and Genentech’s ongoing clinical trials. The Company has incurred losses and negative cash flows from operations since its inception. As of June 30, 2018 , the Company had an accumulated deficit of approximately $971.7 million . The Company anticipates that its $40.4 million of existing cash, cash equivalents and investments at June 30, 2018 should enable it to maintain its planned operations into the second half of 2019. In order to ensure adequate cash resources for 12 months from the issuance date of these financial statements, the Company will reduce or delay spending on its research and development programs and operating expenses to the extent it is unable to raise additional capital through its current at-the-market sale agreement with Cowen and Company, LLC, or Cowen or other potential financing. The Company’s ability to raise additional funds will depend, among other factors, on financial, economic and market conditions, many of which are outside of its control and it may be unable to raise financing in the next 12 months, or on terms favorable to the Company. The Company’s inability to obtain additional funds in the next 12 months would delay, or cause the Company to reduce in scope or eliminate some of its development programs, potentially delaying the time to market for any of its product candidates, and would have a negative impact on the Company’s financial condition and ability to pursue its business strategies.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. These statements, however, are condensed and do not include all disclosures required by accounting principles generally accepted in the U.S., or GAAP, for complete financial statements and should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 as filed with the Securities and Exchange Commission, or the SEC, on March 8, 2018. In the opinion of the Company, the unaudited financial statements contain all adjustments (all of which were considered normal and recurring) necessary for a fair statement of the Company’s financial position at June 30, 2018 and the results of operations for the three and six -month periods ended June 30, 2018 and 2017 and the cash flows for the six -month periods ended June 30, 2018 and 2017 . The condensed consolidated balance sheet at December 31, 2017 was derived from audited annual financial statements but does not contain all of the footnote disclosures from the annual financial statements. Effective as of 5:00 p.m. Eastern Time on May 29, 2018, as previously disclosed, the Company effected a 1-for-5 reverse stock split of its common stock. All references to shares of common stock outstanding, average number of shares outstanding and per share amounts in these consolidated financial statements and notes to consolidated financial statements have been restated to reflect the reverse stock split on a retroactive basis. The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosure of certain assets and liabilities at the balance sheet date. Such estimates include the performance obligations under the Company’s collaboration agreements; the estimated repayment term of the Company’s debt and related short- and long-term classification; the fair value of the Company’s debt; the collectability of receivables; the carrying value of property and equipment and intangible assets; the assumptions used in the Company’s valuation of stock-based compensation and the value of certain investments and liabilities. Actual results may differ from such estimates. These interim results are not necessarily indicative of results to be expected for a full year or subsequent interim periods.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition The Company’s business strategy includes entering into collaborative license and development agreements with biotechnology and pharmaceutical companies for the development and commercialization of the Company’s drug candidates. The terms of the agreements typically include non-refundable license fees, funding of research and development, payments based upon achievement of clinical development and regulatory objectives, and royalties on product sales. The Company has adopted the provisions of the Financial Accounting Standards Board, or FASB, Accounting Standard Codification (ASC) 606, Revenue from Contracts with Customers , or Topic 606. This guidance supersedes the provisions of ASC 605, Revenue Recognition. Under the new guidance, a company can adopt Topic 606 using either the full retrospective method or the modified retrospective method. Under the full retrospective method, a company recasts the amount by which each financial statement line item presented in the current filing is affected as if the new guidance has always existed. Under the modified retrospective method, prior year financial statements would not need to be recast. Instead, a company applies the cumulative effect of initially applying the new standard as an adjustment to the opening retained earnings balance. The Company performed a detailed accounting assessment to quantify the effect of the transition from the former guidance to the new guidance and concluded that there was no material effect on the Company's consolidated financial statements under either the full retrospective or the modified retrospective methods. The Company has concluded that it will elect the modified retrospective method to avoid restatement of prior filings. There are multiple options for the transition method under the new guidance, one of which allows a company to apply this guidance retrospectively either to all contracts at the date of initial application or only to contracts that are not completed contracts at the date of initial application. The Company has elected to apply the guidance to only contracts that are not completed contracts as of January 1, 2018. The only contract not completed as of January 1, 2018 is the collaboration agreement with Genentech (see Note 4). The Company has assessed the potential effects to the consolidated financial statements and retained earnings and has concluded that, upon adoption of the new standard, there was no impact. License Fees and Multiple Element Arrangements If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license at such time as 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 promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation 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 from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. If the Company is involved in a steering committee as part of a multiple element arrangement, the Company assesses whether its involvement constitutes a performance obligation or a right to participate. Steering committee services that are determined to be performance obligations are combined with other research services or performance obligations required under an arrangement, if any, in determining the level of effort required in an arrangement and the period over which the Company expects to complete its aggregate performance obligations. Appropriate methods of measuring progress include output methods and input methods. In determining the appropriate method for measuring progress, the Company considers the nature of service that the Company promises to transfer to the customer. When the Company decides on a method of measurement, the Company will apply that single method of measuring progress for each performance obligation satisfied over time and will apply that method consistently to similar performance obligations and in similar circumstances. If the Company cannot reasonably measure its progress toward complete satisfaction of a performance obligation because it lacks reliable information that would be required to apply an appropriate method of measuring progress, but the Company can reasonably estimate when the performance obligation ceases or the remaining obligations become inconsequential and perfunctory, then revenue is not recognized until the Company can reasonably estimate when the performance obligation ceases or becomes inconsequential. Revenue is then recognized over the remaining estimated period of performance. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. Contingent Research Milestone Payments Under the new guidance, there exists a constraint on the amount of variable consideration included in the transaction price in that either all, or a portion, of an amount of variable consideration should be included in the transaction price. The variable consideration amount should be included only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The assessment of whether variable consideration should be constrained is largely a qualitative one that has two elements: the likelihood of a change in estimate, and the magnitude thereof. Variable consideration is not constrained if the potential reversal of cumulative revenue recognized is not significant, for example. If the consideration in a contract includes a variable amount, a company will estimate the amount of consideration in exchange for transfer of promised goods or services. The consideration also can vary if a company’s entitlement to the consideration is contingent on the occurrence or nonoccurrence of a future event. The Company considers contingent research milestone payments to fall under the scope of variable consideration, which should be estimated for revenue recognition purposes at the inception of the contract and reassessed ongoing at the end of each reporting period. The Company assesses whether contingent research milestones should be considered variable consideration that should be constrained and thus not part of the transaction price. This includes an assessment of the probability that all or some of the milestones revenue could be reversed when the uncertainty around whether or not the achievement of each milestone is resolved, and the amount of reversal could be significant. The guidance provides factors to consider when assessing whether variable consideration should be constrained. All of the factors should be considered, and no factor is determinative. The Company considers all relevant factors. Reimbursement of Costs Reimbursement of research and development costs by third party collaborators is recognized as revenue over time provided the Company has determined that it transfers control (i.e. performs the services) of a service over time and, therefore, satisfies a performance obligation according to the provisions outlined in the ASC 606-10-25-27, Revenue Recognition . Royalty Revenue Since the first quarter of 2012, the Company has recognized royalty revenues related to Genentech’s and Roche’s sales of Erivedge. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes 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). The Company expects to continue recognizing royalty revenue from Genentech’s sales of Erivedge in the U.S. and in other markets where Genentech and Roche successfully obtain marketing approval, if any (see Note 4). However, Erivedge royalties will service Curis Royalty’s debt until this debt is repaid in full (see Note 7). Summary During the six months ended June 30, 2018 and 2017 , total gross revenues are 100% from the Company’s collaboration with Genentech. Deferred Revenue Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Significant judgments are required in the application of revenue recognition guidance. Short-term deferred revenue would consist of amounts that are expected to be recognized as revenue, or applied against future co-development costs, within the next fiscal year. Amounts that the Company expects will not be recognized in the next fiscal year would be classified as long-term deferred revenue. However, this estimate would be based on the Company's operating plan as of the balance sheet date and on its estimated performance periods under the collaboration in which the Company has recorded deferred revenues. If the Company's operating plan or its estimated performance period would change, the Company could recognize a different amount of deferred revenue over the reporting period. With respect to each of the foregoing areas of revenue recognition, the Company exercises significant judgment in determining whether an arrangement contains multiple elements, and, if so, how much revenue is allocable to each element. In addition, the Company exercises its judgment in determining when its significant obligations have been met under such agreements and the specific time periods over which it recognized revenue, such as non-refundable, up-front license fees. To the extent that actual facts and circumstances differ from the Company's initial judgments, its revenue recognition with respect to such transactions would change accordingly and any such change could affect its reported financial results.

Research and Development Collab

Research and Development Collaborations	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and Development Collaborations	Research and Development Collaborations (a) Genentech In June 2003, the Company licensed its proprietary Hedgehog pathway technologies to Genentech for human therapeutic use. The primary focus of the collaborative research plan has been to develop molecules that inhibit the Hedgehog pathway for the treatment of various cancers. The collaboration is currently focused on the development of Erivedge, which is being commercialized by Genentech in the U.S. and by Genentech’s parent company, Roche, in several other countries for the treatment of advanced BCC. Pursuant to the agreement, the Company is eligible to receive up to an aggregate of $115.0 million in contingent cash milestone payments, exclusive of royalty payments, in connection with the development of Erivedge or another small molecule Hedgehog pathway inhibitor, assuming the successful achievement by Genentech and Roche of specified clinical development and regulatory objectives. Of this amount, the Company has received $59.0 million in cash milestone payments as of June 30, 2018 . In addition to these payments and pursuant to the agreement, the Company is entitled to a royalty on net sales of Erivedge that ranges from 5% to 7.5% . The royalty rate applicable to Erivedge may be decreased by 2% on a country-by-country basis in certain specified circumstances, including when a competing product that binds to the same molecular target as Erivedge is approved by the applicable regulatory authority in another country, and is being sold in such country, by a third party for use in the same indication as Erivedge, or, when there is no issued intellectual property covering Erivedge in a territory in which sales are recorded. In 2015, the FDA and the European Medicine Agency’s Committee for Medicinal Products for Human Use, approved another Hedgehog signaling pathway inhibitor, Odomzo® (sonidegib), which is marketed by Sun Pharmaceutical Industries Ltd., for use in locally advanced BCC. Beginning in the fourth quarter of 2015, Genentech applied the 2% royalty reduction on U.S. sales of Erivedge as a result of the first commercial sale of Odomzo® in the U.S. In November 2012, the Company formed a wholly-owned subsidiary, Curis Royalty, to receive a $30.0 million loan, at an annual interest rate of 12.25% , pursuant to a credit agreement between Curis Royalty and BioPharma-II, a Luxembourg limited liability company managed by Pharmakon Advisors (see Note 7). In connection with the loan, the Company transferred to Curis Royalty its right to receive royalty and royalty-related payments from Genentech. The loan and accrued interest was an obligation of Curis Royalty, with no recourse to the Company, to be repaid using the royalty and royalty-related payments from Genentech. In March 2017, the Company and Curis Royalty entered into a new credit agreement with HealthCare Royalty Partners III, L.P., or HealthCare Royalty, for the purpose of refinancing the loan from BioPharma-II. Accordingly, HealthCare Royalty made a $45.0 million loan at an annual interest rate of 9.95% to Curis Royalty, which was used in part to pay off $18.4 million in remaining loan obligations to Biopharma-II under the prior loan, with the residual proceeds of $26.6 million distributed to the Company as sole equity member of Curis Royalty. The Company has identified the following performance obligations related to the Genentech collaboration: 1. To grant the license for its Hedgehog (Hh) antagonist programs and to provide service on both a Joint Steering Committee and Co-Development Steering Committee. This performance obligation has been satisfied and only contingent royalty revenue remains to be recognized in the future. 2. To provide reimbursable research and development services. This performance obligation has been satisfied and no revenue remains to be recognized in the future. The Company recognized $2.4 million and $2.1 million in royalty revenue under the Genentech collaboration during the three months ended June 30, 2018 and 2017 , respectively, and $4.9 million and $4.3 million during the six months ended June 30, 2018 and 2017 , respectively. The Company recorded costs of royalty revenues within the costs and expenses section of its condensed consolidated statements of operations and comprehensive loss of $0.1 million and $0.1 million during the three months ended June 30, 2018 and 2017 , respectively, and $0.3 million and $0.2 million during the six months ended June 30, 2018 and 2017 , respectively. Cost of royalty revenues is comprised of 5% of the royalties earned by Curis Royalty with respect to Erivedge outside Australia, and 2% direct net sales in Australia (subject to decrease on expiration of the patent in April 2019 to 5% of the royalty payments that Curis Royalty receives from Genentech, through February 2022), that the Company is obligated to pay to university licensors. As further discussed in Note 7, the Company expects that all royalty revenues received from Genentech on net sales of Erivedge will be used to pay principal and interest under the loan received from HealthCare Royalty, until such time as the loan is fully repaid. The Company recorded immaterial research and development revenue during the three months ended June 30, 2018 and 2017 , respectively, and an immaterial amount during the six months ended June 30, 2018 and 2017 , respectively, related to expenses incurred by the Company on behalf of Genentech that were paid by the Company and for which Genentech is obligated to reimburse the Company. Genentech incurred expenses of an immaterial amount and $0.1 million during the three months ended June 30, 2018 and 2017 , respectively, and $0.1 million and $0.1 million during the six months ended June 30, 2018 and 2017 , respectively, under this collaboration which the Company is obligated to reimburse to Genentech, and which the Company has recorded as contra-revenues which have been net against research and development revenues in its consolidated statements of operations and comprehensive loss. The Company will continue to recognize revenue for expense reimbursement as such reimbursable expenses are incurred, provided that the provisions of the ASC 606 are met. (b) Aurigene In January 2015, the Company entered into an exclusive collaboration agreement with Aurigene for the discovery, development and commercialization of small molecule compounds in the areas of immuno-oncology and selected precision oncology targets. Under the collaboration agreement, Aurigene granted the Company an option to obtain exclusive, royalty-bearing licenses to relevant Aurigene technology to develop, manufacture and commercialize products containing certain of such compounds anywhere in the world, except for India and Russia, which are territories retained by Aurigene. During 2015, the Company exercised options to license the first two programs under this collaboration, resulting in an aggregate one-time payment of $6.0 million (satisfying the $3.0 million option exercise fee for each program) by the Company to Aurigene. Also in 2015, the Company selected a preclinical program for potential further development within the immuno-oncology part of the collaboration resulting in a one-time payment of $2.0 million . In October 2016, the Company licensed the program and designated CA-327 as the development candidate as described in Note 1, resulting in a one-time payment of $1.5 million . In connection with the collaboration agreement, the Company issued to Aurigene 3,424,026 shares of its common stock valued at $24.3 million in partial consideration for the rights granted to the Company under the collaboration agreement, which the Company recognized as expense during the year ended December 31, 2015. The shares were issued pursuant to a stock purchase agreement with Aurigene dated January 18, 2015. In September 2016, the Company and Aurigene entered into an amendment to the collaboration agreement. Under the terms of the amendment, in exchange for the issuance by the Company to Aurigene of 2,041,666 shares of its common stock, Aurigene waived payment of up to a total of $24.5 million in potential milestones and other payments associated with the first four programs in the collaboration that may have become due from the Company under the collaboration agreement. To the extent any of these waived milestones or other payments are not payable by the Company, for example in the event one or more of the milestone events do not occur, the Company will have the right to deduct the unused waived amount from any one or more of the milestone payment obligations tied to achievement of commercial milestone events. The amendment also provides that, in the event supplemental program activities are performed by Aurigene, the Company will provide up to $2.0 million of additional funding for each of the third and fourth licensed program. The shares were issued pursuant to a stock purchase agreement with Aurigene dated September 7, 2016. As of June 30, 2018 , the Company has exercised its option to license four programs under the collaboration: 1. IRAK4 Program - a precision oncology program of small molecule inhibitors of IRAK4. The development candidate is CA-4948, an orally available small molecule inhibitor of IRAK4. 2. PD1/VISTA Program - an immuno-oncology program of small molecule antagonists of PD1 and VISTA immune checkpoint pathways. The development candidate is CA-170, an orally available small molecule antagonist of PDL1 and VISTA. 3. PD1/TIM3 Program - an immuno-oncology program of small molecule antagonists of PD1 and TIM3 immune checkpoint pathways. The development candidate is CA-327, an orally available small molecule antagonist of PDL1 and TIM3. 4. In March 2018, the Company exercised its option to license a fourth program, which is an immuno-oncology program. For each option to license (as described above) exercised by the Company, the Company is obligated to use commercially reasonable efforts to develop, obtain regulatory approval for, and commercialize at least one product in each of the U.S., specified countries in the European Union and Japan, and Aurigene is obligated to use commercially reasonable efforts to perform its obligations under the development plan for such licensed program in an expeditious manner. Subject to specified exceptions, Aurigene and the Company agreed to collaborate exclusively with each other on the discovery, research, development and commercialization of programs and compounds within immuno-oncology for an initial period of approximately two years from the effective date of the collaboration agreement. At the Company's option, and subject to specified conditions, it may extend such exclusivity for up to three additional one -year periods by paying to Aurigene additional exclusivity option fees on an annual basis. The Company exercised the first one-year exclusivity option fee in the first quarter of 2017. The fee for this exclusivity option exercise was $7.5 million , which the Company paid in two equal installments in the first and third quarters of 2017. The Company has elected not to further exercise its exclusivity option and thus will not make the $10.0 million payment required for this additional exclusivity in 2018. As a result of the Company’s election to not further exercise its exclusivity option, Curis is no longer operating under broad immuno-oncology exclusivity with Aurigene. The Company has, however, as provided in the agreement, elected to exercise its option to extend exclusivity on a program-by-program, year-by-year, basis for the IRAK4 Program and the PD1/VISTA Program, both of the licensed programs currently in clinical trials. Since January 2015, the Company has paid $14.5 million in research payments and has waived $15.5 million in milestone payments under the terms of the 2016 amendment. For each of the IRAK4, PD1/VISTA,PD1/TIM3 programs, and the fourth immuno-oncology program: the Company has remaining unpaid or unwaived payment obligations of $42.5 million per program, related to regulatory approval and commercial sales milestones, plus specified additional payments for approvals for additional indications, if any. In addition to the collaboration agreement, in June 2017, the Company entered into a master development and manufacturing agreement with Aurigene for the supply of drug substance and drug product, under which it has made cash payments to Aurigene totaling $0.8 million .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company discloses fair value measurements based on a framework outlined by GAAP which requires expanded disclosures regarding fair value measurements. GAAP defines 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 on 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. GAAP also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. In accordance with the fair value hierarchy, the following table shows the fair value as of June 30, 2018 and December 31, 2017 of those financial assets and liabilities that are measured at fair value on a recurring basis. Quoted Prices in Active Markets (Level 1) Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Total Fair Value As of June 30, 2018: Cash equivalents: Money market funds $ 26,813 $ — $ — $ 26,813 Corporate commercial paper, bonds and notes — 1,399 — 1,399 Municipal and government securities — 190 — 190 Short-term investments: Corporate commercial paper, stock, bonds and notes — 9,955 — 9,955 Total assets at fair value $ 26,813 $ 11,544 $ — $ 38,357 Quoted Prices in Active Markets (Level 1) Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Total Fair Value As of December 31, 2017: Cash equivalents: Money market funds $ 35,308 $ — $ — $ 35,308 Municipal bonds — 260 — 260 Short-term investments: Corporate commercial paper, stock, bonds and notes — 21,944 — 21,944 Total assets at fair value $ 35,308 $ 22,204 $ — $ 57,512 No investments held at June 30, 2018 were transferred between levels.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Cash equivalents are highly liquid investments purchased with original maturities of three months or less. All other liquid investments are classified as marketable securities. The Company’s short-term investments are marketable securities with original maturities of greater than three months from the date of purchase, but less than twelve months from the balance sheet date, and the Company's long-term investments are marketable securities with original maturities of greater than twelve months from the balance sheet date. Marketable securities consist of commercial paper, corporate bonds and notes, and government obligations. All of the Company’s short-term and long-term investments have been designated available-for-sale and are stated at fair value with any unrealized holding gains or losses included as a component of stockholders’ equity and any realized gains and losses recorded in the statement of operations in the period during which the securities are sold. Unrealized gains and temporary losses on investments are included in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. Realized gains and losses, dividends and interest income are included in other income (expense). Any premium or discount arising at purchase is amortized and/or accreted to interest income. The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of June 30, 2018 are as follows: Amortized Cost Unrealized Gain Unrealized Loss Total Fair Value Corporate bonds and notes – short-term $ 9,956 $ — $ (1 ) $ 9,955 Total investments $ 9,956 $ — $ (1 ) $ 9,955 Short-term investments have maturities ranging from one to 12 months with a weighted-average maturity of 0.1 years at June 30, 2018 . The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2017 are as follows: Amortized Cost Unrealized Gain Unrealized Loss Total Fair Value Corporate bonds and notes – short-term $ 21,946 $ — $ (2 ) $ 21,944 Total investments $ 21,946 $ — $ (2 ) $ 21,944 Short-term investments have maturities ranging from one to 12 months with a weighted-average maturity of 0.2 years at December 31, 2017 . At June 30, 2018 , the Company held 2 debt securities that had been in an unrealized loss position for less than 12 months. The aggregate fair value of these securities was $2.9 million at June 30, 2018 . The Company held no investments that have been in a continuous unrealized loss position for 12 months or longer. The Company evaluated its securities for other-than-temporary impairments based on quantitative and qualitative factors, and considered the decline in market value for the 2 debt securities held as of June 30, 2018 to be primarily attributable to current economic and market conditions. The Company will likely not be required to sell these securities, and the Company does not intend to sell these securities before the recovery of their amortized cost bases, which recovery is expected within the next 12 months. Based on this analysis, the Company does not consider these investments to be other-than-temporarily impaired as of June 30, 2018 .

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt (a) BioPharma-II In December 2012, Curis’ wholly owned subsidiary, Curis Royalty, received a $30.0 million loan at an annual interest rate of 12.25% pursuant to a credit agreement between Curis Royalty and BioPharma-II. In connection with the loan, Curis transferred to Curis Royalty its right to receive royalty and royalty-related payments on the commercial sales of Erivedge that it receives from Genentech (see Note 4(a)). The loan and accrued interest was being repaid by Curis Royalty using such royalty and royalty-related payments. To secure repayment of the loan, Curis Royalty granted a first priority lien and security interest (subject only to permitted liens) to BioPharma-II in all of its assets and all real, intangible and personal property, including all of its right, title and interest in and to the royalty and royalty-related payments. The loan constituted an obligation of Curis Royalty, and was non-recourse to Curis. Under the terms of the loan, quarterly royalty payments received by Curis Royalty from Genentech were first applied to pay, collectively: (i) escrow fees payable by Curis pursuant to an escrow agreement between Curis, Curis Royalty, BioPharma-II and Boston Private Bank and Trust Company, (ii) Curis' royalty obligations to university licensors, (iii) certain expenses incurred by BioPharma-II in connection with the credit agreement and related transaction documents, including enforcement of its rights in the case of an event of default under the credit agreement and (iv) expenses incurred by Curis enforcing its right to indemnification under the collaboration agreement with Genentech. Subsequently, remaining amounts were applied first to pay interest and second, principal on the loan. Curis remained entitled to receive any contingent payments upon achievement of clinical development objectives. Curis Royalty retained its right to royalty payments related to sales of Erivedge following repayment of the loan. The final maturity date of the loan was the earlier of the date when the principal was paid in full or the termination of Curis Royalty’s right to receive royalties under the collaboration agreement with Genentech. Because the repayment of the term loan was contingent upon the level of Erivedge royalties received, the short- and long-term classification of the debt was based on the Company’s estimate of the timing of amounts to be repaid. The Company was not able to estimate when the loan would be repaid as repayments were impacted by numerous factors, all of which were beyond the Company’s control. The repayment term could be shortened or extended depending on the actual level of Erivedge royalties received. In addition, if Erivedge royalties were insufficient to pay the accrued interest on the outstanding loan, any unpaid interest outstanding would be added to the principal on a quarterly basis. At any time after January 1, 2017, Curis Royalty was entitled to, subject to certain limitations, to prepay the outstanding principal of the loan in whole or in part, at a price equal to 105% of the outstanding principal on the loan, plus accrued but unpaid interest. The loan was paid off and terminated in March 2017. (b) HealthCare Royalty Partners III On March 6, 2017, the Company and Curis Royalty entered into a new credit agreement, referred to herein as the credit agreement, with HealthCare Royalty for the purpose of refinancing Curis’ and Curis Royalty’s existing royalty financing arrangement with BioPharma-II, referred to herein as the prior loan. On March 22, 2017, the prior loan was terminated in its entirety. Pursuant to the credit agreement, HealthCare Royalty made a $45.0 million loan at an interest rate of 9.95% to Curis Royalty, which was used to pay off $18.4 million in remaining loan obligations to Biopharma-II under the prior loan. The remaining proceeds of $26.6 million were distributed to Curis as sole equity holder of Curis Royalty. The loan from HealthCare Royalty will be repaid from certain Erivedge royalty and royalty-related payments owed by Genentech under the Genentech collaboration agreement, the rights to which were transferred from Curis to Curis Royalty in 2012. Under the terms of the credit agreement with HealthCare Royalty, quarterly Erivedge royalty and royalty-related payments from Genentech will first be applied to pay, collectively: (i) escrow fees payable by the Company pursuant to an escrow agreement, (ii) the Company’s royalty obligations to academic institutions, (iii) certain expenses incurred by HealthCare Royalty in connection with the credit agreement and related transaction documents, including enforcement of its rights in the case of an event of default under the credit agreement and (iv) expenses incurred by the Company enforcing its right to indemnification under the collaboration agreement. Subsequently, remaining amounts will be applied first, to pay interest and second, to pay principal on the loan. If royalties owed under the Genentech collaboration agreement are insufficient to pay the accrued interest on the outstanding loan, the unpaid interest outstanding will be added to the loan principal on a quarterly basis. (c) Respective Debt Payments to BioPharma-II and HealthCare Royalty Partners III During the six months ended June 30, 2018 and 2017 , Curis Royalty made payments totaling $5.1 million and $4.4 million , respectively, of which $3.1 million and $2.6 million have been applied to the principal, respectively, with the remainder applied to accrued interest. As of June 30, 2018 , the Company recorded short- and long-term debt of $7.0 million and $31.5 million , respectively, and at December 31, 2017 , the Company recorded short- and long-term debt of $5.9 million and $35.7 million , respectively, with such amounts recorded within the Company’s condensed consolidated balance sheets. In addition, the Company recorded related accrued interest on its debt of $0.2 million and $0.2 million as of June 30, 2018 and December 31, 2017 , respectively, with such amounts included in the Company’s accrued liabilities section of its condensed consolidated balance sheets. For the three months ended June 30, 2018 and 2017 , the Company recognized interest expense related to its debt of $1.0 million and $1.1 million , respectively, in the condensed consolidated statement of operations and comprehensive loss. For the six months ended June 30, 2018 and 2017 , the Company recognized interest expense related to its debt of $2.0 million and $1.8 million , respectively, in the condensed consolidated statement of operations and comprehensive loss. At June 30, 2018 , the fair value of the debt approximates its carrying value due to the expected repayment period and because the interest rate yield is near current market rate yields. Due to the assumptions required in estimating future Erivedge royalties, the expected repayment period and weighting of various royalty projection scenarios, the fair value of the debt is measured using Level 3 inputs. During the six months ended June 30, 2017, the Company incurred debt issuance costs totaling $0.2 million in connection with its HealthCare Royalty financing transaction, all of which were incurred directly by the Company. The direct costs incurred by the Company were recorded as contra-debt, which directly reduces the outstanding debt balance on the Company's Consolidated Balance Sheet. All issuance costs will be amortized over the estimated term of the debt using the straight-line method, which approximates the effective interest method. The assumptions used in determining the expected repayment term of the debt and amortization period of the issuance costs requires management to make estimates that could impact the Company’s short- and long-term classification of these costs, as well as the period over which these costs will be amortized.

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 30, 2018
Other Liabilities Disclosure [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consist of the following: June 30, December 31, Accrued compensation $ 2,548 $ 2,187 Professional fees 332 148 Accrued interest on debt (Note 7) 169 193 Other 214 265 Total $ 3,263 $ 2,793

Accounting for Stock-Based Comp

Accounting for Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation As of June 30, 2018 , the Company had two shareholder-approved, share-based compensation plans: (i) the Amended and Restated 2010 Employee Stock Purchase Plan, or the ESPP, adopted by the board of directors in April 2017 and approved by shareholders in June 2017, which amended the 2010 Employee Stock Purchase Plan, and the (ii) the Third Amended and Restated 2010 Stock Incentive Plan, or the 2010 Plan, adopted by the board of directors in March 2018 and approved by shareholders in May 2018, which was amended to, among other things, add an additional 11,950,000 , or 2,390,000 on a post-reverse stock split basis, shares under the 2010 Plan, and set a new expiration date of May 14, 2028 for the 2010 Plan. New employees are typically issued options as an inducement equity award under Nasdaq Listing Rule 5635(c)(4) outside of the 2010 Plan. Effective as of 5:00 p.m. Eastern Time on May 29, 2018, the number of shares of common stock available for issuance under the plans and the number of shares of common stock issuable upon the exercise of then outstanding options have been adjusted to reflect a 1-for-5 reverse stock split. During the six months ended June 30, 2018 , the Company’s board of directors granted options to purchase a total of 1,220,596 shares of the Company’s common stock to employees of the Company, under the 2010 Plan or in the form of inducement awards pursuant to Nasdaq Marketplace Rules. Of these options, options to purchase 783,596 shares were granted to non-officer employees and vest as to 25% of the shares underlying the award after the first year and as to an additional 6.25% of the shares underlying the award in each subsequent quarter, based upon continued employment over a four -year period, and are exercisable at a price equal to the closing price of the Company’s common stock on the Nasdaq Global Market on the grant dates. The Company’s board of directors granted the remaining options to purchase 437,000 shares of the Company’s common stock to its officers in January 2018. Such stock options have an exercise price equal to $3.45 per share, the closing price of the Company’s common stock on the Nasdaq Global Market on the date of grant, and will vest and become exercisable as to 25% of the shares underlying the award after the first year and as to an additional 6.25% of the shares underlying the award in each subsequent quarter, based upon continued employment over a four -year period; provided that such awards would terminate and be forfeited if the Company’s stockholders did not approve an amendment to the 2010 Plan to increase the number of shares authorized for issuance thereunder within 12 months of the grant date; and further provided that such options would not be exercisable and no common stock would be issued thereunder, before the approval of such stock incentive plan amendment by the Company’s stockholders. As mentioned above, the shareholders approved such amendment in May 2018 and options to purchase an aggregate of 437,000 shares of common stock were awarded to the Company’s officers. Also during the six months ended June 30, 2018 , the Company’s board of directors granted restricted stock awards, or RSAs, to officers of the Company for an aggregate amount of 109,250 shares of the Company's common stock under the 2010 Plan. These RSAs will vest as to 25% of the shares underlying the RSA on the first anniversary of the date of grant and as to an additional 25% annually thereafter until all such shares become vested, based upon continued service to the Company over a four -year period. During the six months ended June 30, 2018 , the Company’s board of directors granted RSAs to its non-employee directors for an aggregate amount of 185,000 shares of the Company's common stock under the 2010 Plan. These RSAs will vest as to 100% of the shares underlying the RSA on the first anniversary of the date of grant, subject to continued service to the Company over the course of such year. Employee and Director Grants Vesting Tied to Service Conditions In determining the fair value of stock options, the Company generally uses the Black-Scholes option pricing model. The Black-Scholes option pricing model employs the following key assumptions for employee and director options awarded during the six months ended June 30, 2018 and 2017 based on the assumptions noted in the following table: Six Months Ended 2018 2017 Expected life (years) - employees 5.5 5.5 Expected life (years) - officers 5.5 5.5 Expected life (years) – directors 6.25 6.25 Risk-free interest rate 2.5-2.8% 2.0-2.1% Volatility 66-72% 63-64% Dividends None None The expected volatility is based on the annualized daily historical volatility of the Company’s stock price for a time period consistent with the expected term of each grant. Management believes that the historical volatility of the Company’s stock price best represents the future volatility of the stock price. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for the expected term of the respective grant. The Company has not historically paid cash dividends, and does not expect to pay cash dividends in the foreseeable future. The expected terms and stock price volatility utilized in the calculation involve management’s best estimates at that time, both of which impact the fair value of the option calculated under the Black-Scholes methodology and, ultimately, the expense that will be recognized over the life of the option. GAAP also requires that the Company recognize compensation expense for only the portion of options that are expected to vest. Therefore, management calculated an estimated annual pre-vesting forfeiture rate that is derived from historical employee termination behavior since the inception of the Company, as adjusted. If the actual number of forfeitures differs from those estimated by management, additional adjustments to compensation expense may be required in future periods. A summary of stock option activity under the 2010 Plan, the 2000 Stock Incentive Plan, the 2000 Director Stock Option Plan and nonstatutory inducement awards is summarized as follows: Number of Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Life Aggregate Intrinsic Value Outstanding, December 31, 2017 3,206,858 $ 12.08 Granted 1,220,596 3.19 Exercised — — Canceled (357,742 ) 11.59 Outstanding, June 30, 2018 4,069,712 $ 9.46 7.49 $ — Exercisable at June 30, 2018 1,894,027 $ 12.47 5.77 $ — Vested and unvested expected to vest at June 30, 2018 3,811,106 $ 9.74 7.36 $ — The weighted average grant-date fair values of these stock options granted during the six months ended June 30, 2018 and 2017 were $1.73 and $7.25 , respectively. As of June 30, 2018 , there was approximately $7.5 million of unrecognized compensation cost related to unvested employee stock option awards outstanding, net of the impact of estimated forfeitures, that is expected to be recognized as expense over a weighted-average period of 2.83 years. There were no options exercised during the six months ended June 30, 2018 . The intrinsic value of employee stock options exercised during the six months ended June 30, 2017 was $0.9 million . The following table presents a summary of outstanding RSAs under the 2010 Plan as of June 30, 2018 : Number of Shares Weighted Average Grant Date Fair Value Outstanding, December 31, 2017 — $ — Awarded 294,250 3.45 Vested — — Forfeited — — Outstanding, June 30, 2018 294,250 $ 3.45 As of June 30, 2018 , there were 294,250 shares outstanding covered by RSAs that are expected to vest. The weighted average fair value of these shares of restricted stock was $3.45 per share and the aggregate fair value of these shares of restricted stock was approximately $1.0 million . As of June 30, 2018 , there were approximately $0.6 million of unrecognized compensation costs, net of estimated forfeitures, related to RSAs granted to officers and non-employee directors, which are expected to be recognized as expense over a remaining weighted average period of 1.67 years. Employee Stock-Based Compensation Expense The Company recorded a total of $1.2 million and $2.4 million , respectively, in compensation expense for the three and six months ended June 30, 2018 and $1.6 million and $2.7 million , respectively, for the three and six months ended June 30, 2017 related to employee and director stock option grants. The total fair values of vested stock options for each of the six months ended June 30, 2018 and 2017 was $1.8 million and $2.1 million , respectively. The Company recorded $0.2 million and $0.3 million in compensation expense during the three and six months ended June 30, 2018 , net of expected forfeitures, related to officer and director restricted stock awards. Total Stock-Based Compensation Expense For the three and six months ended June 30, 2018 and 2017 , the Company recorded stock-based compensation expense to the following line items in its costs and expenses section of the condensed consolidated statements of operations and comprehensive loss, including expense related to its ESPP: Three Months Ended Six Months Ended 2018 2017 2018 2017 Research and development expenses $ 436 $ 414 $ 849 $ 703 General and administrative expenses 753 1,171 1,566 1,985 Total stock-based compensation expense $ 1,189 $ 1,585 $ 2,415 $ 2,688

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following tables summarize the changes in accumulated other comprehensive income (loss) as of June 30, 2018 and 2017 : Unrealized Gain on Securities Available-for-Sale Balance, as of December 31, 2017 $ (2 ) Unrealized loss on marketable securities 1 Amounts reclassified from accumulated other comprehensive income (loss) — Net current period other comprehensive income 1 Balance, as of June 30, 2018 $ (1 ) The above amounts do not reflect a tax effect because the Company expects to record a net loss for 2018 . Unrealized Losses and Gain on Securities Available-for-Sale Balance, as of December 31, 2016 $ (4 ) Unrealized loss on marketable securities 1 Amounts reclassified from accumulated other comprehensive income (loss) — Net current period other comprehensive income 1 Balance, as of June 30, 2017 $ (3 )

Common Stock and Treasury Stock

Common Stock and Treasury Stock	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Common Stock and Treasury Stock	Common Stock and Treasury Stock Effective as of 5:00 p.m. Eastern Time on May 29, 2018, all share amounts and per share amounts have been adjusted to reflect a 1-for-5 reverse stock split. (a) ATM Sales Agreement On July 2, 2015, the Company entered into a sales agreement with Cowen and Company, LLC, or Cowen, pursuant to which the Company may sell from time to time up to $30.0 million of the Company’s common stock through an “at-the-market” equity offering program under which Cowen acts as sales agent. Subject to the terms and conditions of the sales agreement, Cowen may sell the common stock by methods deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended. In addition, with the Company’s prior written approval, Cowen may also sell the common stock by any other method permitted by law, including pursuant to negotiated transactions. Cowen is obligated to use its commercially reasonable efforts consistent with its normal trading and sales practices and applicable state and federal laws, rules and regulations and the rules of the Nasdaq Global Market to sell on the Company’s behalf all of the shares requested to be sold by the Company. The Company has no obligation to sell any of the common stock under the sales agreement. Either the Company or Cowen may at any time suspend solicitations and offers under the sales agreement upon notice to the other party. The sales agreement may be terminated at any time by either the Company or Cowen upon written notice to the other party as specified in the sales agreement. The aggregate compensation payable to Cowen shall be 3% of the gross sales price of the common stock sold by Cowen pursuant to the sales agreement. Each party has agreed in the sales agreement to provide indemnification and contribution against certain liabilities, including liabilities under the Securities Act, subject to the terms of the sales agreement. The shares sold under the sales agreement have been issued and sold pursuant to the universal shelf registration statement on Form S-3, filed with the Securities and Exchange Commission on July 2, 2015. Since inception, the Company has sold 420,796 shares of common stock under this sales agreement for net proceeds of $6.2 million . The remaining shares that may be sold under the sales agreement are expected to be issued and sold, if at all, pursuant to the currently effective universal shelf registration statement on Form S-3, filed with the Securities and Exchange Commission on May 3, 2018. (b) Treasury Stock Retirement Since 2002, the Company has repurchased 244,569 shares of common stock at a total cost of $1.5 million . The shares were repurchased through a combination of a repurchase program of up to $3.0 million approved by the Board of Directors in 2002 and through employee purchases of common stock upon the exercise of stock options by remittance of shares of Company stock. The Company accounts for its common stock repurchases as treasury stock under the cost method. In March 2018, the Company retired all 244,569 shares of common stock at a total cost of $1.5 million . This was a non-cash transaction and thus only affected the classifications within the stockholders' equity section of the Company's consolidated balance sheet.

Loss Per Common Share

Loss Per Common Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Loss Per Common Share	Loss Per Common Share Basic and diluted loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per common share is the same as basic net loss per common share for the three months ended June 30, 2018 and 2017 , because the effect of the potential common stock equivalents would be antidilutive due to the Company’s net loss position for these periods. Antidilutive securities consist of stock options outstanding of 4,069,712 and 3,714,413 as of June 30, 2018 and 2017 , respectively.

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In June 2018, the FASB issued Accounting Standard Update (ASU) 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-based Payment Accounting , which simplifies the accounting for nonemployee share-based payment transactions resulting from expanding the scope of ASC 718, Compensation - Stock Compensation . The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2018, and early adoption is permitted, but no earlier than an entity's adoption date of ASC 606, Revenue from Contracts with Customers . The Company does not have any outstanding nonemployee awards as of June 30, 2018 , and has adopted this update as of that date. There is no impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting , which clarifies the scope under which modification accounting should be applied to a share-based payment award under ASC 718. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is permitted for interim or annual periods beginning after January 1, 2017. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment , which simplifies the subsequent measurement of goodwill under the current standard in testing the interim or annual impairment of goodwill. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2019, and early adoption is permitted for interim or annual period beginning after January 1, 2017. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , which helps to clarify the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under ASC 230, Statement of Cash Flows , by addressing eight specific cash flow issues. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is permitted for interim or annual periods. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases . The standard requires organizations that lease assets to recognize on the balance sheet assets or liabilities, as applicable, for the rights and obligations created by those leases. Additionally, the guidance modifies current guidance for lessor accounting and leveraged leases, and is effective for fiscal years beginning after December 15, 2018, and interim periods within such years. Early adoption is permitted, but the Company does not anticipate electing early adoption. The Company has begun to assess the current state of accounting for leases, to catalog all current leases effected and understand the gaps between the current state and required future state and to implement the new processes and controls required. The Company currently expects that adoption of this standard will increase both total assets and liabilities in its consolidated financial statements and is currently evaluating whether the impact will be material. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which amends prior guidance on accounting for equity investments and financial liabilities. The new standard amends certain aspects of accounting and disclosure requirements for financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in results of operations. The new standard does not apply to investments accounted for under the equity method of accounting or those that result in consolidation of the investee. Equity investments that do not have readily determinable fair values may be measured at fair value or at cost minus impairment adjusted for changes in observable prices. A financial liability that is measured at fair value in accordance with the fair value option is required to be presented separately in other comprehensive income for the portion of the total change in the fair value resulting from change in the instrument-specific credit risk. In addition, a valuation allowance should be evaluated on deferred tax assets related to available-for-sale debt securities in combination with other deferred tax assets. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within such years. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In May 2014, the FASB issued new revenue recognition guidance in ASU 2014-09, Revenue from Contracts with Customers , for entities, providing a single, comprehensive model to account for revenue arising from contracts with customers. In addition, The FASB recently issued ASUs 2016-08, 2016-10, 2016-12, 2016-20 and 2017-13, all of which are further clarifying amendments to ASU 2014-09. This new standard provides a five step framework whereby revenue is recognized when promised goods or services are transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The new standard also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Two adoption methods are permitted: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. The Company adopted the modified retrospective method. To date, the Company’s sources of collaboration and other revenue have primarily been collaboration agreements. The most significant differences between Topic 606 and previous guidance for license and collaboration revenue are: (i) allocating consideration to performance obligations; and (ii) estimating and determining the timing of recognition of variable consideration received from licensees, including up-front license payments, contingent milestones and royalties. The guidance is effective for interim and annual periods beginning after December 15, 2017 and early adoption is permitted. The Company has adopted the guidance as of January 1, 2018. The Company has evaluated the impact that ASU 2014-09 may have on the financial position and results of operations and has concluded that the adoption of this guidance has no material impact on its consolidated financial statements. For more detail, see Note 3, Revenue Recognition .

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. These statements, however, are condensed and do not include all disclosures required by accounting principles generally accepted in the U.S., or GAAP, for complete financial statements and should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 as filed with the Securities and Exchange Commission, or the SEC, on March 8, 2018. In the opinion of the Company, the unaudited financial statements contain all adjustments (all of which were considered normal and recurring) necessary for a fair statement of the Company’s financial position at June 30, 2018 and the results of operations for the three and six -month periods ended June 30, 2018 and 2017 and the cash flows for the six -month periods ended June 30, 2018 and 2017 . The condensed consolidated balance sheet at December 31, 2017 was derived from audited annual financial statements but does not contain all of the footnote disclosures from the annual financial statements. Effective as of 5:00 p.m. Eastern Time on May 29, 2018, as previously disclosed, the Company effected a 1-for-5 reverse stock split of its common stock. All references to shares of common stock outstanding, average number of shares outstanding and per share amounts in these consolidated financial statements and notes to consolidated financial statements have been restated to reflect the reverse stock split on a retroactive basis. The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosure of certain assets and liabilities at the balance sheet date. Such estimates include the performance obligations under the Company’s collaboration agreements; the estimated repayment term of the Company’s debt and related short- and long-term classification; the fair value of the Company’s debt; the collectability of receivables; the carrying value of property and equipment and intangible assets; the assumptions used in the Company’s valuation of stock-based compensation and the value of certain investments and liabilities. Actual results may differ from such estimates. These interim results are not necessarily indicative of results to be expected for a full year or subsequent interim periods.
Revenue Recognition	Deferred Revenue Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Significant judgments are required in the application of revenue recognition guidance. Short-term deferred revenue would consist of amounts that are expected to be recognized as revenue, or applied against future co-development costs, within the next fiscal year. Amounts that the Company expects will not be recognized in the next fiscal year would be classified as long-term deferred revenue. However, this estimate would be based on the Company's operating plan as of the balance sheet date and on its estimated performance periods under the collaboration in which the Company has recorded deferred revenues. If the Company's operating plan or its estimated performance period would change, the Company could recognize a different amount of deferred revenue over the reporting period. With respect to each of the foregoing areas of revenue recognition, the Company exercises significant judgment in determining whether an arrangement contains multiple elements, and, if so, how much revenue is allocable to each element. In addition, the Company exercises its judgment in determining when its significant obligations have been met under such agreements and the specific time periods over which it recognized revenue, such as non-refundable, up-front license fees. To the extent that actual facts and circumstances differ from the Company's initial judgments, its revenue recognition with respect to such transactions would change accordingly and any such change could affect its reported financial results. Revenue Recognition The Company’s business strategy includes entering into collaborative license and development agreements with biotechnology and pharmaceutical companies for the development and commercialization of the Company’s drug candidates. The terms of the agreements typically include non-refundable license fees, funding of research and development, payments based upon achievement of clinical development and regulatory objectives, and royalties on product sales. The Company has adopted the provisions of the Financial Accounting Standards Board, or FASB, Accounting Standard Codification (ASC) 606, Revenue from Contracts with Customers , or Topic 606. This guidance supersedes the provisions of ASC 605, Revenue Recognition. Under the new guidance, a company can adopt Topic 606 using either the full retrospective method or the modified retrospective method. Under the full retrospective method, a company recasts the amount by which each financial statement line item presented in the current filing is affected as if the new guidance has always existed. Under the modified retrospective method, prior year financial statements would not need to be recast. Instead, a company applies the cumulative effect of initially applying the new standard as an adjustment to the opening retained earnings balance. The Company performed a detailed accounting assessment to quantify the effect of the transition from the former guidance to the new guidance and concluded that there was no material effect on the Company's consolidated financial statements under either the full retrospective or the modified retrospective methods. The Company has concluded that it will elect the modified retrospective method to avoid restatement of prior filings. There are multiple options for the transition method under the new guidance, one of which allows a company to apply this guidance retrospectively either to all contracts at the date of initial application or only to contracts that are not completed contracts at the date of initial application. The Company has elected to apply the guidance to only contracts that are not completed contracts as of January 1, 2018. The only contract not completed as of January 1, 2018 is the collaboration agreement with Genentech (see Note 4). The Company has assessed the potential effects to the consolidated financial statements and retained earnings and has concluded that, upon adoption of the new standard, there was no impact. License Fees and Multiple Element Arrangements If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license at such time as 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 promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation 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 from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. If the Company is involved in a steering committee as part of a multiple element arrangement, the Company assesses whether its involvement constitutes a performance obligation or a right to participate. Steering committee services that are determined to be performance obligations are combined with other research services or performance obligations required under an arrangement, if any, in determining the level of effort required in an arrangement and the period over which the Company expects to complete its aggregate performance obligations. Appropriate methods of measuring progress include output methods and input methods. In determining the appropriate method for measuring progress, the Company considers the nature of service that the Company promises to transfer to the customer. When the Company decides on a method of measurement, the Company will apply that single method of measuring progress for each performance obligation satisfied over time and will apply that method consistently to similar performance obligations and in similar circumstances. If the Company cannot reasonably measure its progress toward complete satisfaction of a performance obligation because it lacks reliable information that would be required to apply an appropriate method of measuring progress, but the Company can reasonably estimate when the performance obligation ceases or the remaining obligations become inconsequential and perfunctory, then revenue is not recognized until the Company can reasonably estimate when the performance obligation ceases or becomes inconsequential. Revenue is then recognized over the remaining estimated period of performance. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. Contingent Research Milestone Payments Under the new guidance, there exists a constraint on the amount of variable consideration included in the transaction price in that either all, or a portion, of an amount of variable consideration should be included in the transaction price. The variable consideration amount should be included only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The assessment of whether variable consideration should be constrained is largely a qualitative one that has two elements: the likelihood of a change in estimate, and the magnitude thereof. Variable consideration is not constrained if the potential reversal of cumulative revenue recognized is not significant, for example. If the consideration in a contract includes a variable amount, a company will estimate the amount of consideration in exchange for transfer of promised goods or services. The consideration also can vary if a company’s entitlement to the consideration is contingent on the occurrence or nonoccurrence of a future event. The Company considers contingent research milestone payments to fall under the scope of variable consideration, which should be estimated for revenue recognition purposes at the inception of the contract and reassessed ongoing at the end of each reporting period. The Company assesses whether contingent research milestones should be considered variable consideration that should be constrained and thus not part of the transaction price. This includes an assessment of the probability that all or some of the milestones revenue could be reversed when the uncertainty around whether or not the achievement of each milestone is resolved, and the amount of reversal could be significant. The guidance provides factors to consider when assessing whether variable consideration should be constrained. All of the factors should be considered, and no factor is determinative. The Company considers all relevant factors. Reimbursement of Costs Reimbursement of research and development costs by third party collaborators is recognized as revenue over time provided the Company has determined that it transfers control (i.e. performs the services) of a service over time and, therefore, satisfies a performance obligation according to the provisions outlined in the ASC 606-10-25-27, Revenue Recognition . Royalty Revenue Since the first quarter of 2012, the Company has recognized royalty revenues related to Genentech’s and Roche’s sales of Erivedge. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes 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). The Company expects to continue recognizing royalty revenue from Genentech’s sales of Erivedge in the U.S. and in other markets where Genentech and Roche successfully obtain marketing approval, if any (see Note 4). However, Erivedge royalties will service Curis Royalty’s debt until this debt is repaid in full (see Note 7).
Fair Value Measurements	Fair Value Measurements The Company discloses fair value measurements based on a framework outlined by GAAP which requires expanded disclosures regarding fair value measurements. GAAP defines 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 on 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. GAAP also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Loss Per Common Share	Loss Per Common Share Basic and diluted loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per common share is the same as basic net loss per common share for the three months ended June 30, 2018 and 2017 , because the effect of the potential common stock equivalents would be antidilutive due to the Company’s net loss position for these periods.
New Accounting Pronouncements	New Accounting Pronouncements In June 2018, the FASB issued Accounting Standard Update (ASU) 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-based Payment Accounting , which simplifies the accounting for nonemployee share-based payment transactions resulting from expanding the scope of ASC 718, Compensation - Stock Compensation . The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2018, and early adoption is permitted, but no earlier than an entity's adoption date of ASC 606, Revenue from Contracts with Customers . The Company does not have any outstanding nonemployee awards as of June 30, 2018 , and has adopted this update as of that date. There is no impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting , which clarifies the scope under which modification accounting should be applied to a share-based payment award under ASC 718. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is permitted for interim or annual periods beginning after January 1, 2017. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment , which simplifies the subsequent measurement of goodwill under the current standard in testing the interim or annual impairment of goodwill. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2019, and early adoption is permitted for interim or annual period beginning after January 1, 2017. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , which helps to clarify the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under ASC 230, Statement of Cash Flows , by addressing eight specific cash flow issues. The standard will be effective for annual reporting periods and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is permitted for interim or annual periods. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases . The standard requires organizations that lease assets to recognize on the balance sheet assets or liabilities, as applicable, for the rights and obligations created by those leases. Additionally, the guidance modifies current guidance for lessor accounting and leveraged leases, and is effective for fiscal years beginning after December 15, 2018, and interim periods within such years. Early adoption is permitted, but the Company does not anticipate electing early adoption. The Company has begun to assess the current state of accounting for leases, to catalog all current leases effected and understand the gaps between the current state and required future state and to implement the new processes and controls required. The Company currently expects that adoption of this standard will increase both total assets and liabilities in its consolidated financial statements and is currently evaluating whether the impact will be material. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which amends prior guidance on accounting for equity investments and financial liabilities. The new standard amends certain aspects of accounting and disclosure requirements for financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in results of operations. The new standard does not apply to investments accounted for under the equity method of accounting or those that result in consolidation of the investee. Equity investments that do not have readily determinable fair values may be measured at fair value or at cost minus impairment adjusted for changes in observable prices. A financial liability that is measured at fair value in accordance with the fair value option is required to be presented separately in other comprehensive income for the portion of the total change in the fair value resulting from change in the instrument-specific credit risk. In addition, a valuation allowance should be evaluated on deferred tax assets related to available-for-sale debt securities in combination with other deferred tax assets. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within such years. As such, the Company adopted this standard as of January 1, 2018 and concluded there was no material impact on its consolidated financial statements. In May 2014, the FASB issued new revenue recognition guidance in ASU 2014-09, Revenue from Contracts with Customers , for entities, providing a single, comprehensive model to account for revenue arising from contracts with customers. In addition, The FASB recently issued ASUs 2016-08, 2016-10, 2016-12, 2016-20 and 2017-13, all of which are further clarifying amendments to ASU 2014-09. This new standard provides a five step framework whereby revenue is recognized when promised goods or services are transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The new standard also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Two adoption methods are permitted: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. The Company adopted the modified retrospective method. To date, the Company’s sources of collaboration and other revenue have primarily been collaboration agreements. The most significant differences between Topic 606 and previous guidance for license and collaboration revenue are: (i) allocating consideration to performance obligations; and (ii) estimating and determining the timing of recognition of variable consideration received from licensees, including up-front license payments, contingent milestones and royalties. The guidance is effective for interim and annual periods beginning after December 15, 2017 and early adoption is permitted. The Company has adopted the guidance as of January 1, 2018. The Company has evaluated the impact that ASU 2014-09 may have on the financial position and results of operations and has concluded that the adoption of this guidance has no material impact on its consolidated financial statements. For more detail, see Note 3, Revenue Recognition .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Financial Assets or Liabilities Measured at Fair Value on Recurring Basis	In accordance with the fair value hierarchy, the following table shows the fair value as of June 30, 2018 and December 31, 2017 of those financial assets and liabilities that are measured at fair value on a recurring basis. Quoted Prices in Active Markets (Level 1) Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Total Fair Value As of June 30, 2018: Cash equivalents: Money market funds $ 26,813 $ — $ — $ 26,813 Corporate commercial paper, bonds and notes — 1,399 — 1,399 Municipal and government securities — 190 — 190 Short-term investments: Corporate commercial paper, stock, bonds and notes — 9,955 — 9,955 Total assets at fair value $ 26,813 $ 11,544 $ — $ 38,357 Quoted Prices in Active Markets (Level 1) Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Total Fair Value As of December 31, 2017: Cash equivalents: Money market funds $ 35,308 $ — $ — $ 35,308 Municipal bonds — 260 — 260 Short-term investments: Corporate commercial paper, stock, bonds and notes — 21,944 — 21,944 Total assets at fair value $ 35,308 $ 22,204 $ — $ 57,512

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost of Unrealized Gains and Losses and Fair Value of Investments	The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of June 30, 2018 are as follows: Amortized Cost Unrealized Gain Unrealized Loss Total Fair Value Corporate bonds and notes – short-term $ 9,956 $ — $ (1 ) $ 9,955 Total investments $ 9,956 $ — $ (1 ) $ 9,955 The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2017 are as follows: Amortized Cost Unrealized Gain Unrealized Loss Total Fair Value Corporate bonds and notes – short-term $ 21,946 $ — $ (2 ) $ 21,944 Total investments $ 21,946 $ — $ (2 ) $ 21,944

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Other Liabilities Disclosure [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consist of the following: June 30, December 31, Accrued compensation $ 2,548 $ 2,187 Professional fees 332 148 Accrued interest on debt (Note 7) 169 193 Other 214 265 Total $ 3,263 $ 2,793

Accounting for Stock-Based Co23

Accounting for Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Key Assumptions for Options Awarded	The Black-Scholes option pricing model employs the following key assumptions for employee and director options awarded during the six months ended June 30, 2018 and 2017 based on the assumptions noted in the following table: Six Months Ended 2018 2017 Expected life (years) - employees 5.5 5.5 Expected life (years) - officers 5.5 5.5 Expected life (years) – directors 6.25 6.25 Risk-free interest rate 2.5-2.8% 2.0-2.1% Volatility 66-72% 63-64% Dividends None None
Schedule of Stock Option Activity	A summary of stock option activity under the 2010 Plan, the 2000 Stock Incentive Plan, the 2000 Director Stock Option Plan and nonstatutory inducement awards is summarized as follows: Number of Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Life Aggregate Intrinsic Value Outstanding, December 31, 2017 3,206,858 $ 12.08 Granted 1,220,596 3.19 Exercised — — Canceled (357,742 ) 11.59 Outstanding, June 30, 2018 4,069,712 $ 9.46 7.49 $ — Exercisable at June 30, 2018 1,894,027 $ 12.47 5.77 $ — Vested and unvested expected to vest at June 30, 2018 3,811,106 $ 9.74 7.36 $ —
Schedule of Restricted Stock Award Activity	The following table presents a summary of outstanding RSAs under the 2010 Plan as of June 30, 2018 : Number of Shares Weighted Average Grant Date Fair Value Outstanding, December 31, 2017 — $ — Awarded 294,250 3.45 Vested — — Forfeited — — Outstanding, June 30, 2018 294,250 $ 3.45
Schedule of Stock-Based Compensation Expense	For the three and six months ended June 30, 2018 and 2017 , the Company recorded stock-based compensation expense to the following line items in its costs and expenses section of the condensed consolidated statements of operations and comprehensive loss, including expense related to its ESPP: Three Months Ended Six Months Ended 2018 2017 2018 2017 Research and development expenses $ 436 $ 414 $ 849 $ 703 General and administrative expenses 753 1,171 1,566 1,985 Total stock-based compensation expense $ 1,189 $ 1,585 $ 2,415 $ 2,688

Accumulated Other Comprehensi24

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss)	The following tables summarize the changes in accumulated other comprehensive income (loss) as of June 30, 2018 and 2017 : Unrealized Gain on Securities Available-for-Sale Balance, as of December 31, 2017 $ (2 ) Unrealized loss on marketable securities 1 Amounts reclassified from accumulated other comprehensive income (loss) — Net current period other comprehensive income 1 Balance, as of June 30, 2018 $ (1 ) The above amounts do not reflect a tax effect because the Company expects to record a net loss for 2018 . Unrealized Losses and Gain on Securities Available-for-Sale Balance, as of December 31, 2016 $ (4 ) Unrealized loss on marketable securities 1 Amounts reclassified from accumulated other comprehensive income (loss) — Net current period other comprehensive income 1 Balance, as of June 30, 2017 $ (3 )

Nature of Business - Narrative

Nature of Business - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)segment	Dec. 31, 2017USD ($)	Oct. 31, 2016program	Dec. 31, 2015program	Oct. 31, 2015program
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of reportable segments | segment	1
Retained earnings (accumulated deficit)	$ (971,676)	$ (952,265)
Cash, cash equivalents and investments	$ 40,400
Aurigene
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of programs licensed in collaboration agreement | program			3	2	2

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details)	May 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reverse stock split ratio	0.2

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Genentech, Inc. | Customer Concentration Risk
Concentration Risk [Line Items]
Total gross revenues (as a percent)	100.00%	100.00%

Research and Development Coll28

Research and Development Collaborations - Narrative (Details)	Mar. 06, 2017USD ($)	Apr. 30, 2019	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Oct. 31, 2016USD ($)program	Sep. 30, 2016USD ($)shares	Jan. 31, 2015USD ($)paymentproductterm	Jun. 30, 2003USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2015USD ($)program	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2015USD ($)programshares	Dec. 31, 2017USD ($)	Oct. 31, 2015program	Dec. 31, 2012USD ($)	Nov. 30, 2012USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Distribution of remaining loan proceeds	$ 26,600,000			$ 26,600,000
Recognized royalty revenue									$ 2,358,000	$ 2,061,000		$ 4,826,000	$ 4,192,000
Cost of royalty revenues									134,000	96,000		263,000	207,000
Option fees							$ 7,500,000
Value of common stock issued									332,000			332,000			$ 331,000
Collaboration agreement, number of optional additional terms | term							3
Collaboration agreement, optional additional term							1 year
Number of payments | payment							2
Exclusivity payment												10,000,000
Royalties
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized royalty revenue									2,394,000	2,102,000		4,868,000	4,294,000
Curis Royalty, LLC | Credit agreement with BioPharma-II
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Principal loan amount to Curis Royalty given by BioPharma under credit agreement																	$ 30,000,000	$ 30,000,000
Interest rate on loan to Curis Royalty given by BioPharma under credit agreement																	12.25%	12.25%
Genentech, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount received for specified clinical development and regulatory objectives									59,000,000			59,000,000
Percentage of royalty rate decrease								2.00%			2.00%
Cost of royalty revenues									100,000	100,000		$ 300,000	200,000
Percentage of royalties earned												5.00%
Genentech, Inc. | Royalties
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized royalty revenue									2,400,000	2,100,000		$ 4,900,000	4,300,000
Genentech, Inc. | Drug development royalty
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expenses									100,000	100,000		100,000	100,000
Genentech, Inc. | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible to receive contingent cash payment for specified clinical development and regulatory objectives (up to)								$ 115,000,000
Percentage of royalty on net sales								7.50%
Genentech, Inc. | Minimum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalty on net sales								5.00%
HealthCare Royalty Partners III, L.P. | Curis Royalty, LLC
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Principal loan amount to Curis Royalty given by BioPharma under credit agreement	$ 45,000,000		$ 45,000,000							$ 45,000,000			$ 45,000,000
Interest rate on loan to Curis Royalty given by BioPharma under credit agreement	9.95%		9.95%							9.95%			9.95%
BioPharma-II | Curis Royalty, LLC
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining loan obligations	$ 18,400,000		$ 18,400,000							$ 18,400,000			$ 18,400,000
Aurigene
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of programs licensed in collaboration agreement | program					3						2			2		2
Collaboration agreement payment														$ 6,000,000
Option fees														3,000,000
Additional payments made under collaborative arrangements (up to)											$ 2,000,000			$ 2,000,000
One-time payment					$ 1,500,000
Issued shares of common stock (in shares) | shares														3,424,026
Value of common stock issued											$ 24,300,000			$ 24,300,000
Shares issued of common stock in exchange for waived payment (in shares) | shares						2,041,666
Waived payment of milestone and other payments (up to)						$ 24,500,000
Collaboration agreement, number of products required to commercialize (at least) | product							1
Collaboration agreement period							2 years
Milestone payments waived to date									15,500,000			15,500,000
Aurigene | Programs three and four
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Agreement to provide additional funding, if options are exercised (up to)						2,000,000
Payments made under collaboration arrangements									$ 14,500,000			$ 14,500,000
Aurigene | IRAK4, PD1/VISTA,PD1/TIM3 Program
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Waived payment of milestone and other payments (up to)						$ 42,500,000
Aurigene | Master Development and Manufacturing Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement payment			$ 800,000
Forecast | Genentech, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalty payments		5.00%
Australia | Genentech, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of direct net sales												2.00%

Fair Value Measurements - Summa

Fair Value Measurements - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Short-term investments:
Total assets at fair value	$ 38,357	$ 57,512
Corporate commercial paper, stock, bonds and notes
Short-term investments:
Corporate commercial paper, stock, bonds and notes	9,955	21,944
Money market funds
Cash equivalents:
Cash equivalents	26,813	35,308
Corporate commercial paper, bonds and notes
Cash equivalents:
Cash equivalents	1,399
Municipal and government securities
Cash equivalents:
Cash equivalents	190	260
Quoted Prices in Active Markets (Level 1)
Short-term investments:
Total assets at fair value	26,813	35,308
Quoted Prices in Active Markets (Level 1) | Corporate commercial paper, stock, bonds and notes
Short-term investments:
Corporate commercial paper, stock, bonds and notes	0	0
Quoted Prices in Active Markets (Level 1) | Money market funds
Cash equivalents:
Cash equivalents	26,813	35,308
Quoted Prices in Active Markets (Level 1) | Corporate commercial paper, bonds and notes
Cash equivalents:
Cash equivalents	0
Quoted Prices in Active Markets (Level 1) | Municipal and government securities
Cash equivalents:
Cash equivalents	0	0
Other Observable Inputs (Level 2)
Short-term investments:
Total assets at fair value	11,544	22,204
Other Observable Inputs (Level 2) | Corporate commercial paper, stock, bonds and notes
Short-term investments:
Corporate commercial paper, stock, bonds and notes	9,955	21,944
Other Observable Inputs (Level 2) | Money market funds
Cash equivalents:
Cash equivalents	0	0
Other Observable Inputs (Level 2) | Corporate commercial paper, bonds and notes
Cash equivalents:
Cash equivalents	1,399
Other Observable Inputs (Level 2) | Municipal and government securities
Cash equivalents:
Cash equivalents	190	260
Unobservable Inputs (Level 3)
Short-term investments:
Total assets at fair value	0	0
Unobservable Inputs (Level 3) | Corporate commercial paper, stock, bonds and notes
Short-term investments:
Corporate commercial paper, stock, bonds and notes	0	0
Unobservable Inputs (Level 3) | Money market funds
Cash equivalents:
Cash equivalents	0	0
Unobservable Inputs (Level 3) | Corporate commercial paper, bonds and notes
Cash equivalents:
Cash equivalents	0
Unobservable Inputs (Level 3) | Municipal and government securities
Cash equivalents:
Cash equivalents	$ 0	$ 0

Investments - Narrative (Detail

Investments - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)security	Dec. 31, 2017
Debt Securities
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	2
Value of securities in a continuous unrealized loss position for less than 12 months | $	$ 2.9
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Weighted-average maturity of short-term investments	24 days	2 months
Short-term Investments | Minimum
Debt Securities, Available-for-sale [Line Items]
Maturity range for short-term investments	1 month	1 month
Short-term Investments | Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity range for short-term investments	12 months	12 months

Investments - Amortized Cost of

Investments - Amortized Cost of Unrealized Gains and Losses and Fair Value of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 9,956	$ 21,946
Unrealized Gain	0	0
Unrealized Loss	(1)	(2)
Total Fair Value	9,955	21,944
Corporate bonds and notes – short-term
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,956	21,946
Unrealized Gain	0	0
Unrealized Loss	(1)	(2)
Total Fair Value	$ 9,955	$ 21,944

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Mar. 06, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2012	Nov. 30, 2012
Debt Instrument [Line Items]
Distribution of remaining loan proceeds	$ 26,600,000	$ 26,600,000
Payment towards debt obligations					$ 3,074,000	$ 2,607,000
Short-term debt			$ 6,965,000		6,965,000		$ 5,886,000
Long-term debt			31,532,000		31,532,000		35,669,000
Interest expense recognized related to loan			993,000	$ 1,119,000	2,018,000	1,775,000
BioPharma-II
Debt Instrument [Line Items]
Interest expense recognized related to loan			$ 1,000,000	1,100,000	2,000,000	1,800,000
HealthCare Royalty Partners III, L.P.
Debt Instrument [Line Items]
Debt issuance costs				200,000		200,000
Curis Royalty, LLC | HealthCare Royalty Partners III, L.P.
Debt Instrument [Line Items]
Loan received	$ 45,000,000			$ 45,000,000		$ 45,000,000
Annual interest rate	9.95%			9.95%		9.95%
Curis Royalty, LLC | BioPharma-II
Debt Instrument [Line Items]
Remaining loan obligations	$ 18,400,000			$ 18,400,000		$ 18,400,000
Credit agreement with BioPharma-II
Debt Instrument [Line Items]
Accrued interest on loan amount to Curis Royalty given by BioPharma under credit agreement					200,000		$ 200,000
Credit agreement with BioPharma-II | Curis Royalty, LLC
Debt Instrument [Line Items]
Loan received								$ 30,000,000	$ 30,000,000
Annual interest rate								12.25%	12.25%
Percentage equal to the price of the outstanding principal of the loan that may be prepaid								105.00%
Payment towards debt obligations					5,100,000	4,400,000
Credit agreement with BioPharma-II | Curis Royalty, LLC | Principal portion
Debt Instrument [Line Items]
Payment towards debt obligations					$ 3,100,000	$ 2,600,000

Accrued Liabilities - Summary (

Accrued Liabilities - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Accrued compensation	$ 2,548	$ 2,187
Professional fees	332	148
Accrued interest on debt (Note 7)	169	193
Other	214	265
Total	$ 3,263	$ 2,793

Accounting for Stock-Based Co34

Accounting for Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	May 29, 2018shares	Jun. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)plan$ / sharesshares	Jun. 30, 2017USD ($)$ / shares	May 28, 2018shares	Dec. 31, 2017$ / sharesshares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shareholder-approved, share-based compensation plans | plan				2
Reverse stock split ratio	0.2
Number of options granted (shares)				1,220,596
Weighted average grant-date fair values of stock options (USD per share) | $ / shares				$ 1.73	$ 7.25
Unrecognized compensation cost, net of estimated forfeitures | $		$ 7,500		$ 7,500
Unrecognized compensation cost, weighted average period for recognition				2 years 10 months
Intrinsic values of employee stock options exercised | $					$ 900
Compensation expense related to employee and director stock option grants | $		$ 1,189	$ 1,585	$ 2,415	2,688
Fair values of vested stock options | $				$ 1,800	2,100
Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Weighted average fair value (USD per share) | $ / shares		$ 3.45		$ 3.45			$ 0
Awarded (shares)				294,250
Outstanding shares (shares)		294,250		294,250			0
Fair value | $				$ 1,000
Stock options outstanding
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Compensation expense related to employee and director stock option grants | $		$ 1,200	$ 1,600	$ 2,400	$ 2,700
Officers | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period of options				4 years
Awarded (shares)				109,250
Non-employee directors | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option				100.00%
Awarded (shares)				185,000
Officers and Non-Employee Directors | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Unrecognized compensation cost, net of estimated forfeitures | $		600		$ 600
Unrecognized compensation cost, weighted average period for recognition				1 year 8 months
Compensation expense related to employee and director stock option grants | $		$ 200		$ 300
Tranche one | Officers | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option				25.00%
Tranche two | Officers | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option				25.00%
2010 Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,390,000					11,950,000
Number of options granted (shares)				1,220,596
Vesting period of options				4 years
2010 Plan | Tranche one
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options vested (share)				783,596
Percentage of vested shares which are exercisable under stock option				25.00%
2010 Plan | Tranche two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options vested (share)				437,000
Percentage of vested shares which are exercisable under stock option				6.25%

Accounting for Stock-Based Co35

Accounting for Stock-Based Compensation - Key Assumptions (Details)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Risk-free interest rate (minimum) (as a percent)	2.50%	2.00%
Risk-free interest rate (maximum) (as a percent)	2.80%	2.10%
Volatility (minimum) (as a percent)	66.00%	63.00%
Volatility (maximum) (as a percent)	72.00%	64.00%
Employees
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Expected life	5 years 6 months	5 years 6 months
Officers
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Expected life	5 years 6 months	5 years 6 months
Directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Expected life	6 years 3 months	6 years 3 months

Accounting for Stock-Based Co36

Accounting for Stock-Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Number of Shares
Beginning balance (shares) | shares	3,206,858
Granted (shares) | shares	1,220,596
Exercised (shares) | shares	0
Canceled (shares) | shares	(357,742)
Ending balance (shares) | shares	4,069,712
Exercisable at period end (shares) | shares	1,894,027
Vested and unvested expected to vest (shares) | shares	3,811,106
Weighted Average Exercise Price per Share
Beginning balance (USD per share) | $ / shares	$ 12.08
Granted (USD per share) | $ / shares	3.19
Exercised (USD per share) | $ / shares	0
Canceled (USD per share) | $ / shares	11.59
Ending balance (USD per share) | $ / shares	9.46
Exercisable at period end (USD per share) | $ / shares	12.47
Vested and unvested expected to vest (USD per share) | $ / shares	$ 9.74
Weighted Average Remaining Contractual Life
Outstanding, June 30, 2018	7 years 5 months 28 days
Exercisable at June 30, 2018	5 years 9 months 7 days
Vested and unvested expected to vest at June 30, 2018	7 years 4 months 10 days
Aggregate Intrinsic Value
Outstanding, June 30, 2018 | $	$ 0
Exercisable at June 30, 2018 | $	0
Vested and unvested expected to vest at June 30, 2018 | $	$ 0

Accounting for Stock-Based Co37

Accounting for Stock-Based Compensation - Restricted Stock Award Activity (Details) - Restricted Stock	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Number of Shares
Beginning balance (shares) | shares	0
Awarded (shares) | shares	294,250
Vested (shares) | shares	0
Forfeited (shares) | shares	0
Ending balance (shares) | shares	294,250
Weighted Average Grant Date Fair Value
Beginning balance (USD per share) | $ / shares	$ 0
Vested (USD per share) | $ / shares	0
Awarded (USD per share) | $ / shares	3.45
Forfeited (USD per share) | $ / shares	0
Ending balance (USD per share) | $ / shares	$ 3.45

Accounting for Stock-Based Co38

Accounting for Stock-Based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	$ 1,189	$ 1,585	$ 2,415	$ 2,688
Research and development expenses
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	436	414	849	703
General and administrative expenses
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	$ 753	$ 1,171	$ 1,566	$ 1,985

Accumulated Other Comprehensi39

Accumulated Other Comprehensive Income (Loss) - Summary (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 23,993
Ending balance	7,110
Accumulated net unrealized investment gain (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2)	$ (4)
Unrealized loss on marketable securities	1	1
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current period other comprehensive income	1	1
Ending balance	$ (1)	$ (3)

Common Stock and Treasury Sto40

Common Stock and Treasury Stock - Narrative (Details)	May 29, 2018	Jul. 02, 2015USD ($)	Mar. 31, 2018USD ($)shares	Jun. 30, 2018USD ($)shares	Jun. 30, 2017USD ($)
Class of Stock [Line Items]
Reverse stock split ratio	0.2
Proceeds from issuance of common stock associated with offerings, net of issuance costs				$ 0	$ 6,214,000
Shares repurchased to date (shares) | shares				244,569
Cost of repurchased shares to date				$ 1,500,000
Authorized amount of shares for repurchase (up to)				$ 3,000,000
Common stock retired (shares) | shares			244,569
Value of common stock retired			$ 1,500,000
Cowen | At-the-market sale facility
Class of Stock [Line Items]
Planned proceeds from sale of stock (up to)		$ 30,000,000
Compensation payable, percentage of gross sales price		3.00%
Shares of common stock sold (shares) | shares				420,796
Proceeds from issuance of common stock associated with offerings, net of issuance costs				$ 6,200,000

Loss Per Common Share - Narrati

Loss Per Common Share - Narrative (Details) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Stock options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (shares)	4,069,712	3,714,413