Infinity Pharmaceuticals (INFIQ) 10-Q 3 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 28, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Trading Symbol	INFI
Entity Registrant Name	INFINITY PHARMACEUTICALS, INC.
Entity Central Index Key	1,113,148
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		50,689,512

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 66,197	$ 74,060
Available-for-sale securities	0	18,004
Restricted cash	515	1,152
Prepaid expenses and other current assets	2,065	8,444
Total current assets	68,777	101,660
Property and equipment, net	22,040	23,424
Restricted cash, less current portion	0	530
Other assets	28	41
Total assets	90,845	125,655
Current liabilities:
Accounts payable	581	2,413
Accrued expenses	9,899	21,008
Financing obligation, current (note 10)	456	442
Total current liabilities	10,936	23,863
Deferred rent (note 10)	186	183
Financing obligation, less current portion (note 10)	20,799	19,149
Other liabilities	22	6
Total liabilities	31,943	43,201
Commitments and contingencies
Stockholders’ equity:
Preferred Stock, $0.001 par value; 1,000,000 shares authorized, no shares issued and outstanding at June 30, 2017 and December 31, 2016	0	0
Common Stock, $0.001 par value; 100,000,000 shares authorized, and 50,483,357 and 50,374,871 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	50	50
Additional paid-in capital	711,970	708,096
Accumulated deficit	(653,118)	(625,689)
Accumulated other comprehensive loss	0	(3)
Total stockholders’ equity	58,902	82,454
Total liabilities and stockholders’ equity	$ 90,845	$ 125,655

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	100,000,000	100,000,000
Common Stock, shares issued (in shares)	50,483,357	50,374,871
Common Stock, shares outstanding (in shares)	50,483,357	50,374,871

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Collaboration revenue	$ 0	$ 9,467	$ 0	$ 18,723
Operating expenses:
Research and development	3,901	52,947	7,940	92,135
General and administrative	6,205	15,692	12,642	26,528
Total operating expenses	10,106	68,639	20,582	118,663
Gain on AbbVie Opt-Out (note 8)	0	112,216	0	112,216
Income (loss) from operations	(10,106)	53,044	(20,582)	12,276
Other income (expense):
Interest expense	(300)	(307)	(602)	(616)
Other expense (note 10)	(6,882)	0	(6,882)	0
Investment and other income (loss)	334	254	637	667
Total other income (expense)	(6,848)	(53)	(6,847)	51
Net income (loss)	$ (16,954)	$ 52,991	$ (27,429)	$ 12,327
Earnings (loss) per common share:
Basic (in dollars per share)	$ (0.34)	$ 1.05	$ (0.54)	$ 0.24
Diluted (in dollars per share)	$ (0.34)	$ 1.05	$ (0.54)	$ 0.24
Weighted average number of common shares outstanding:
Basic (in shares)	50,455,832	49,437,062	50,439,682	49,388,475
Diluted (in shares)	50,455,832	49,439,537	50,439,682	49,399,926
Other comprehensive income (loss):
Net unrealized holding gains (losses) on available-for-sale securities arising during the period	$ 0	$ (38)	$ 3	$ (43)
Comprehensive income (loss)	$ (16,954)	$ 52,953	$ (27,426)	$ 12,284

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities
Net income (loss)	$ (27,429)	$ 12,327
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Non-cash gain on AbbVie Opt-Out	0	(112,216)
Depreciation	1,384	1,386
Stock-based compensation, including 401(k) match	3,804	7,528
Non-cash adjustment to financing obligation	1,882	0
Impairment of property and equipment	0	1,773
Other, net	8	114
Changes in operating assets and liabilities:
Prepaid expenses and other assets	6,391	172
Accounts payable, accrued expenses and other liabilities	(12,925)	9,307
Deferred revenue	0	(18,723)
Deferred rent	3	32
Net cash used in operating activities	(26,882)	(98,300)
Investing activities
Purchases of property and equipment	0	(638)
Purchases of available-for-sale securities	0	(39,692)
Proceeds from maturities of available-for-sale securities	18,000	60,601
Proceeds from sales of available-for-sale securities	0	11,953
Net cash provided by investing activities	18,000	32,224
Financing activities
Proceeds from issuances of common stock related to stock incentive plans and awards	70	444
Proceeds from issuances of common stock related to employee stock purchase plan	0	18
Release of restricted cash	1,167	0
Payments on financing obligation	(218)	(205)
Net cash provided by financing activities	1,019	257
Net decrease in cash and cash equivalents	(7,863)	(65,819)
Cash and cash equivalents at beginning of period	74,060	188,170
Cash and cash equivalents at end of period	66,197	122,351
Supplemental cash flow information
Cash paid for interest	$ 602	$ 616

Organization

Organization	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Infinity Pharmaceuticals, Inc., is an innovative biopharmaceutical company dedicated to advancing novel medicines for people with cancer. As used throughout these unaudited, condensed consolidated financial statements, the terms “Infinity,” “we,” “us,” and “our” refer to the business of Infinity Pharmaceuticals, Inc., and its wholly-owned subsidiaries.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation These condensed consolidated financial statements include the accounts of Infinity and its wholly-owned subsidiaries. We have eliminated all significant intercompany accounts and transactions in consolidation. The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the accompanying condensed consolidated financial statements have been included. Interim results for the three and six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 . The information presented in the condensed consolidated financial statements and related footnotes at June 30, 2017 , and for the three and six months ended June 30, 2017 and 2016 , is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2016 have been derived from our audited financial statements. For further information, please refer to the consolidated financial statements and accompanying footnotes included in our annual report on Form 10-K for the fiscal year ended December 31, 2016 filed with the U.S. Securities and Exchange Commission, or SEC, on March 14, 2017, which we refer to as our 2016 Annual Report on Form 10-K. Liquidity We have generated an accumulated deficit of $ 653.1 million and will require substantial additional capital to fund operations. Our future success is dependent on our ability to develop our sole clinical stage product candidate, IPI-549, an orally administered immuno-oncology product candidate that selectively inhibits the enzyme phosphoinositide-3-kinase-gamma, or PI3K-gamma, and ultimately upon our ability to attain profitable operations. We are subject to a number of risks similar to other life science companies seeking to develop and commercialize pharmaceuticals, including, but not limited to, risks relating to the successful development of IPI-549 and our need for additional funding, which may not be available. As of June 30, 2017 , we had cash and cash equivalents of $66.2 million . Excluding the potential $6.0 million and $22.0 million contingent payments in cash or stock from Verastem Inc., or Verastem (see Note 8), we believe that our current cash and cash equivalents will be adequate to satisfy our capital needs based on planned levels of spending into the first quarter of 2019. For more information, refer to the section titled “Liquidity and Capital Resources” in Item 2, Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Our significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in our 2016 Annual Report on Form 10-K. Segment Information We operate in one business segment, which focuses on drug development. We make operating decisions based upon the performance of the enterprise as a whole and utilize our consolidated financial statements for decision making. All of our revenues since September 2006 have been generated under collaboration agreements. Basic and Diluted Net Income (Loss) per Common Share Basic net income (loss) per share is based upon the weighted average number of common shares outstanding during the period, excluding restricted stock that has been issued but has not yet vested. Diluted net income (loss) per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options and the exercise of outstanding warrants (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method) and the vesting of restricted shares of common stock. In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. The two-class method is used for outstanding warrants as such warrants are considered to be participating securities, and such method is more dilutive than the treasury stock method. The following outstanding shares of common stock equivalents were excluded from the computation of net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock options 8,120,150 9,194,421 8,120,150 9,128,732 Warrants (excluded from treasury stock method) 1,000,000 1,000,000 1,000,000 1,000,000 Unvested restricted stock 663,811 — 663,811 — Basic and diluted earnings (loss) per common share were determined as follows: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands, except share and per share amounts) Basic Net income (loss) $ (16,954 ) $ 52,991 $ (27,429 ) $ 12,327 Undistributed earnings allocated to warrants — (1,051 ) — (245 ) Net income (loss) $ (16,954 ) $ 51,940 $ (27,429 ) $ 12,082 Weighted average common shares outstanding 50,455,832 49,437,062 50,439,682 49,388,475 Basic earnings (loss) per common share $ (0.34 ) $ 1.05 $ (0.54 ) $ 0.24 Diluted Net income (loss) $ (16,954 ) $ 52,991 $ (27,429 ) $ 12,327 Undistributed earnings allocated to warrants — (1,051 ) — (245 ) Net income (loss) $ (16,954 ) $ 51,940 $ (27,429 ) $ 12,082 Weighted average common shares outstanding 50,455,832 49,437,062 50,439,682 49,388,475 Effect of dilutive options — 2,475 — 11,451 Weighted average common shares outstanding assuming dilution 50,455,832 49,439,537 50,439,682 49,399,926 Diluted earnings (loss) per common share $ (0.34 ) $ 1.05 $ (0.54 ) $ 0.24 New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2014-9, Revenue from Contracts with Customers , or ASU No. 2014-9, which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. ASU No. 2014-9 was originally effective for interim and annual periods beginning after December 15, 2016. In August 2015, the FASB issued a one-year deferral of the effective date of this standard to annual reporting periods, and interim reporting periods within those years, beginning after December 15, 2017. Entities are allowed to adopt the standard as of the original effective date. The standard allows for two transition methods - full retrospective, in which the standard is applied to each prior reporting period presented or modified retrospective, in which the cumulative effect of initially applying the standard recognized at the date of initial adoption. We expect to elect the modified retrospective approach and are continuing to evaluate the impact that ASU No. 2014-09 may have on our consolidated financial statements in connection with collaboration and license agreements. In November 2016, FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash, or ASU No. 2016-18. ASU No. 2016-18 provides guidance on the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. Under ASU No. 2016-18, the statement of cash flows shall explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Amounts generally described as restricted cash and cash equivalents should now be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statements of cash flows. The amendments of this ASU are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. Other than the revised statement of cash flows presentation, the adoption of ASU No. 2016-18 is not expected to have an impact on our condensed consolidated financial statements. Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU No. 2016-09, which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification of cash flows. We adopted ASU No. 2016-09 as of January 1, 2017. Under the new standard, all excess tax benefits and tax deficiencies are recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards are treated as discrete items in the reporting period in which they occur. We applied the modified retrospective adoption approach upon adoption of the standard, and prior periods have not been adjusted. As a result, we established a net operating loss deferred tax asset of $7.5 million to account for prior period excess tax benefits through retained earnings, and an offsetting valuation allowance of $7.5 million through retained earnings, because it is not more likely than not that the deferred tax asset will be realized due to historical and expected future losses. We elected to recognize forfeitures related to employee share-based payments as they occur. There was no material impact on our financial statements as a result of the adoption of this guidance.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Total stock-based compensation expense related to all equity awards for the three and six months ended June 30, 2017 and 2016 was comprised of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands) Research and development $ 394 $ 2,090 $ 1,101 $ 3,966 General and administrative 1,603 1,723 2,703 3,562 Total stock-based compensation expense $ 1,997 $ 3,813 $ 3,804 $ 7,528 As of June 30, 2017 , we had approximately $7.5 million of total unrecognized compensation cost related to unvested common stock options, restricted common stock and awards under our Employee Stock Purchase Plan, or ESPP, which are expected to be recognized over a weighted-average period of 1.3 years . Restricted Stock During the six months ended June 30, 2017 , no restricted stock was granted, 133,300 shares of restricted stock were forfeited, and no restricted stock vested. As of June 30, 2017 , 663,811 shares of restricted stock are issued and unvested. The restricted stock will vest based on the achievement of specified performance conditions. We recognized $0.3 million of stock compensation expense for the three months ended June 30, 2017 related to restricted stock the vesting of which was determined to be probable as of June 30, 2017 and that vested on July 21, 2017 based on achievement of a specified performance condition. Stock Options During the six months ended June 30, 2017 , we granted options to purchase 4,708,500 shares of our common stock at a weighted average fair value of $1.17 per share and a weighted average exercise price of $1.61 per share. During the six months ended June 30, 2016 , we granted options to purchase 1,617,472 shares of our common stock at a weighted average fair value of $3.75 per share and a weighted average exercise price of $6.14 per share. For the three and six months ended June 30, 2017 and 2016 , the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Risk-free interest rate 1.8 % 1.3 % 1.9 % 1.8 % Expected annual dividend yield — — — — Expected stock price volatility 90.0 % 86.7 % 90.0 % 73.0 % Expected term of options 5.7 years 4.9 years 5.6 years 5.4 years During the six months ended June 30, 2017 , no options to purchase shares of common stock were exercised. Employee Stock Purchase Plan We temporarily suspended the ESPP program on June 24, 2016, and our Board of Directors approved the commencement of a new offering period in June 2017. The weighted-average fair value of each purchase right granted during the six months ended June 30, 2017 and June 30, 2016 was $0.98 and $2.91 , respectively. For the six months ended June 30, 2017 and June 30, 2016 , the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions: Six Months Ended June 30, 2017 2016 Risk-free interest rate 1.2 % 0.8 % Expected annual dividend yield — — Expected stock price volatility 101.8 % 63.5 % Expected term 1.3 years 1.3 years

Cash, Cash Equivalents and Avai

Cash, Cash Equivalents and Available-for-Sale Securities	6 Months Ended
	Jun. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Available-for-Sale Securities	Cash, Cash Equivalents and Available-for-Sale Securities The following is a summary of cash, cash equivalents and available-for-sale securities: June 30, 2017 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 66,197 $ — $ — $ 66,197 Total cash and cash equivalents $ 66,197 $ — $ — $ 66,197 December 31, 2016 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 74,060 $ — $ — $ 74,060 Available-for-sale securities: U.S. Treasury securities due in one year or less 6,753 — (1 ) 6,752 U.S. government-sponsored enterprise obligations due in one year or less 11,254 — (2 ) 11,252 Total available-for-sale securities 18,007 — (3 ) 18,004 Total cash, cash equivalents and available-for-sale securities $ 92,067 $ — $ (3 ) $ 92,064 During the six months ended June 30, 2017 , all of our available-for-sale securities matured. We had no material realized gains or losses on our available-for-sale securities for the three and six months ended June 30, 2017 and 2016 . There were no other-than-temporary impairments recognized for the three and six months ended June 30, 2017 and 2016 .

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value	Fair Value We use a valuation hierarchy for disclosure of the inputs used to measure fair value. This hierarchy prioritizes the inputs into three broad levels. Level 1 inputs, which we consider the highest level inputs, are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The classification of a financial asset or liability within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. For our fixed income securities, we reference pricing data supplied by our custodial agent and nationally known pricing vendors, using a variety of daily data sources, largely readily-available market data and broker/dealer quotes. We validate the prices provided by our third party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources. After completing our validation procedures, we did not adjust or override any fair value measurements provided by our pricing services as of June 30, 2017 and December 31, 2016 . The following table provides the assets carried at fair value measured on a recurring basis as of June 30, 2017 and December 31, 2016 : Level 1 Level 2 (in thousands) June 30, 2017 Assets: Cash and cash equivalents $ 66,197 $ — Total $ 66,197 $ — December 31, 2016 Assets: Cash and cash equivalents $ 61,008 $ 13,052 U.S. Treasury securities — 6,752 U.S. government-sponsored enterprise obligations — 11,252 Total $ 61,008 $ 31,056 The carrying amounts reflected in the condensed consolidated balance sheets for prepaid expenses and other current assets, other assets, accounts payable and accrued expenses approximate their fair value due to their short-term maturities. There have been no changes to our valuation methods during the six months ended June 30, 2017 . We evaluate transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1 and Level 2 during the six months ended June 30, 2017 . We had no available-for-sale securities that were classified as Level 3 at any point during the six months ended June 30, 2017 or during the year ended December 31, 2016 .

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	6 Months Ended
	Jun. 30, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets Prepaid expenses and other current assets consist of the following: June 30, 2017 December 31, 2016 (in thousands) Prepaid expenses $ 1,492 $ 3,336 Other current assets 484 5,023 Value-added tax receivable 89 85 Total prepaid expenses and other current assets $ 2,065 $ 8,444

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	Collaborations Takeda In July 2010, we entered into a development and license agreement with Intellikine, Inc., or Intellikine, under which we obtained rights to discover, develop and commercialize pharmaceutical products targeting the gamma and/or delta isoforms of PI3K, including IPI-549 and duvelisib, an oral, dual inhibitor of PI3K delta and gamma. In January 2012, Intellikine was acquired by Takeda Pharmaceuticals Company Limited acting through its Millennium business unit. We refer to our PI3K inhibitor program licensor as Takeda. In December 2012, we amended and restated our development and license agreement with Takeda and further amended the agreement in July 2014 and September 2016. We refer to the amended and restated development and license agreement, as amended, as the Takeda Agreement. On July 27, 2017, we entered into a third amendment to the Takeda Agreement, which terminated our obligations to Takeda under the Takeda Agreement to pay royalties with respect to worldwide net sales of products containing or comprised of a selective inhibitor of PI3K gamma, including but not limited to IPI-549. See Note 12 for the details of this amendment. Under the terms of the Takeda Agreement, we are obligated to pay Takeda an aggregate of up to $5.0 million in success-based milestone payments for the development of a product candidate other than duvelisib, which could include IPI-549. We are also obligated to pay Takeda up to an aggregate of $165 million in remaining success-based milestone payments related to the approval and commercialization of one product candidate other than duvelisib, which could be IPI-549. Under the September 2016 amendment to the Takeda Agreement, and in connection with our entry into the Verastem Agreement, we are no longer obligated to pay Takeda any remaining milestone payments for the development, approval or commercialization of duvelisib. In return, we are obligated to pay Takeda 50% of all revenue arising from certain qualifying transactions for duvelisib including those under the license agreement we entered into with Verastem, described in more detail below, subject to certain exceptions including revenue we receive as reimbursement for duvelisib research and development expenses. Except for duvelisib in oncology indications, IPI-549, and other products containing a selective inhibitor of PI3K-gamma, including IPI-549, we are obligated to pay Takeda tiered royalties ranging from 7% to 11% on worldwide net sales of products described in the agreement. Such royalties are payable until the later to occur of the expiration of specified patent rights and the expiration of non-patent regulatory exclusivities in a country, subject to reduction of the royalties and, in certain circumstances, limits on the number of products subject to a royalty obligation. The Takeda Agreement expires on the later of the expiration of certain patents and the expiration of the royalty payment terms for the products, unless earlier terminated in accordance with its terms. Either party may terminate the Takeda Agreement on 75 days ’ prior written notice if the other party materially breaches the agreement and fails to cure such breach within the applicable notice period, provided that the notice period is reduced to 30 days where the alleged breach is non-payment. Takeda may also terminate the Takeda Agreement if we are not diligent in developing or commercializing the licensed products and do not, within three months after notice from Takeda, demonstrate to Takeda’s reasonable satisfaction that we have not failed to be diligent. The foregoing periods are subject to extension in certain circumstances. Additionally, Takeda may terminate the Takeda Agreement upon 30 days ’ prior written notice if we or a related party bring an action challenging the validity of any of the licensed patents, provided that we have not withdrawn such action before the end of the 30 -day notice period. We may terminate the agreement at any time upon 180 days ’ prior written notice. The Takeda Agreement also provides for customary reciprocal indemnification obligations of the parties. Verastem On October 29, 2016, we and Verastem entered into a license agreement, which we and Verastem amended and restated on November 1, 2016, effective as of October 29, 2016. We refer to the amended and restated license agreement as the Verastem Agreement. Under the Verastem Agreement, we granted to Verastem an exclusive worldwide license for the research, development, commercialization, and manufacture of duvelisib and products containing duvelisib, which we refer to as the Licensed Products, in each case in oncology indications. Upon entry into the Verastem Agreement, Verastem has assumed financial responsibility for activities that were part of our ongoing duvelisib program, including a randomized, Phase 3 monotherapy clinical study in patients with relapsed/refractory chronic lymphocytic leukemia, which we refer to as the DUO Study. Verastem is obligated to use diligent efforts, as defined in the Verastem Agreement, to develop and commercialize one Licensed Product. During the term of the Verastem Agreement, we have agreed not to research, develop, manufacture or commercialize duvelisib in any indication in humans or animals. Under the Verastem Agreement, we have financial responsibility for up to $4.5 million of costs related to the shutdown of certain specified clinical studies. We have incurred the $4.5 million maximum for clinical study shutdown costs through June 30, 2017 . Following a short transition period, which terminated December 31, 2016, Verastem assumed all financial and operational responsibility for the duvelisib program except for the clinical shutdown costs and certain clinical close-out activities that we agreed to retain. Verastem will reimburse us for costs incurred by us during the transition period and certain prepaid expenses associated with the clinical studies assumed by Verastem. As of June 30, 2017 , we recognized a receivable from Verastem of $0.1 million included in prepaid expenses and other current assets that represents reimbursements of our costs incurred during the three months ended June 30, 2017 . Pursuant to the terms of the Verastem Agreement, Verastem is required to make the following payments to us in cash or, at Verastem’s election, in whole or in part, in shares of Verastem common stock: (i) $6.0 million upon the completion of the DUO Study if the results of the DUO Study meet certain pre-specified criteria and (ii) $22.0 million upon the approval for a Licensed Product of a new drug application, or NDA, in the United States or an application for marketing authorization with a regulatory authority outside of the United States. For any portion of any of the foregoing payments which Verastem elects to issue in shares of common stock in lieu of cash, the number of shares of Verastem common stock to be issued would be determined by multiplying (1) 1.025 by (2) the number of shares of common stock equal to (a) the amount of the payment to be paid in shares of common stock divided by (b) the average closing price of a share of common stock as quoted on NASDAQ for a twenty day period following the public announcement of the applicable event. The shares of common stock would be issued as unregistered securities, and Verastem would have an obligation to promptly file a registration statement with the SEC to register such shares for resale. Any issuance of shares would be subject to the satisfaction of standard closing conditions, including that all material authorizations, consents, and similar approvals necessary for such issuance shall have been obtained. Verastem is also obligated to pay us royalties on worldwide net sales of Licensed Products ranging from the mid-single digits to the high-single digits. The royalty obligation will continue on a product-by-product and country-by-country basis until the latest to occur of (i) the last-to-expire patent right covering the applicable Licensed Product in the applicable country, (ii) the last-to-expire patent right covering the manufacture of the applicable Licensed Product in the country of manufacture of such Licensed Product, (iii) the expiration of non-patent regulatory exclusivity for such Licensed Product in the applicable country and (iv) ten years following the first commercial sale of a Licensed Product in the applicable country, provided that upon the expiration of the last-to-expire patent right covering the Licensed Product in the United States, the applicable royalty on net sales for such Licensed Product in the United States will be reduced by 50% . The royalties are also subject to reduction by 50% of certain third-party royalty payments or patent litigation damages or settlements which might be required to be paid by Verastem if litigation were to arise, with any such reductions capped at 50% of the amounts otherwise payable during the applicable royalty payment period. In addition to the foregoing, Verastem is obligated to pay us a royalty of 4% on worldwide net sales of Licensed Products to cover the reimbursement of research and development costs owed by us to Mundipharma International Corporation Limited, or Mundipharma, and Purdue Pharmaceutical Products L.P., or Purdue. We refer to this royalty obligation as the Trailing Mundipharma Royalties. Once we have fully reimbursed Mundipharma and Purdue, the Trailing Mundipharma Royalties will be reduced to 1% of net sales in the United States. The Trailing Mundipharma Royalties are payable on a product-by-product basis until the latest to occur of (i) the last-to-expire patent right covering the applicable Licensed Product in the United States, (ii) the last-to-expire patent right covering the manufacture of the applicable Licensed Product in the country of manufacture of such Licensed Product, (iii) the expiration of non-patent regulatory exclusivity for such Licensed Product in the United States and (iv) ten years following the first commercial sale of such Licensed Product in the United States, provided that, upon the expiration of the last-to-expire patent right covering a Licensed Product in the United States, the applicable royalty on net sales for such Licensed Product in the United States will be reduced by 50% . In addition, the Trailing Mundipharma Royalties are subject to reduction by 50% of certain third-party royalty payments or patent litigation damages or settlements which might be required to be paid by Verastem if litigation were to arise, with any such reductions capped at 50% of the amounts otherwise payable during the applicable royalty payment period. The Verastem Agreement expires when each party no longer has any obligations to the other party under the Verastem Agreement. Verastem has the right to terminate the Verastem Agreement upon at least 180 days’ prior written notice to us at any time following the earlier of (i) Verastem’s decision to discontinue the DUO Study under certain circumstances as specified in the Verastem Agreement and (ii) the determination of whether the DUO Study has met its pre-specified primary endpoint. Either party may terminate the Verastem Agreement if the other party materially breaches or defaults in the performance of its obligations. If we terminate the Verastem Agreement for Verastem’s material breach, patent challenge, or insolvency, or if Verastem terminates for convenience, then, at our request and subject to our execution of a waiver of certain types of damages, Verastem will transition the duvelisib program back to us at Verastem’s cost. If Verastem terminates for our breach or insolvency, Verastem will effect a more limited transition of the duvelisib program to us at our request and cost, subject to our execution of a waiver of certain types of damages, and we will thereafter pay to Verastem a low single-digit royalty on net sales of Licensed Products. We and Verastem have made customary representations and warranties and have agreed to certain customary covenants, including confidentiality and indemnification. AbbVie On September 2, 2014, we entered into a collaboration and license agreement with AbbVie Inc., or AbbVie, which we refer to as the AbbVie Agreement. Under the AbbVie Agreement, we and AbbVie agreed to develop and commercialize in oncology indications products containing duvelisib. We refer to products containing duvelisib as Duvelisib Products. IPI-549 was excluded from the collaboration. On June 24, 2016, AbbVie delivered to us a written notice that AbbVie was exercising its right to terminate the AbbVie Agreement unilaterally upon 90 days ’ written notice, which we refer to as the AbbVie Opt-Out. The termination of the AbbVie Agreement was effective on September 23, 2016. The AbbVie Opt-Out was irrevocable, and we had no obligation to continue to provide AbbVie any services related to Duvelisib Products after June 24, 2016. We recognized $9.5 million and $18.7 million during the three and six months ended June 30, 2016 , respectively, of revenue related to the development and committee services provided through June 24, 2016. We recorded the remaining amounts already received from AbbVie and allocated to development and committee services of $112.2 million as a gain during the three months ended June 30, 2016 , reflecting the fact that we are no longer obligated to provide any such services and have no obligation to refund any of the payments received to date. Under the terms of the AbbVie Agreement, we and AbbVie agreed to share equally commercial profits or losses of Duvelisib Products in the United States, and AbbVie agreed to pay us tiered royalties on net sales of Duvelisib Products outside the United States. We and AbbVie shared oversight of development and agreed to use diligent efforts, as defined in the AbbVie Agreement, to carry out our development activities under an agreed upon development plan. We had primary responsibility for the conduct of development of Duvelisib Products and had the initial responsibility to manufacture Duvelisib Products. AbbVie had responsibility for the conduct of certain contemplated combination clinical studies, which we refer to as the AbbVie Studies. Excluding the AbbVie Studies, we were responsible for all costs to develop and manufacture Duvelisib Products up to a maximum amount of $667 million . The development and manufacturing costs for the AbbVie Studies were shared equally. During the three and six months ended June 30, 2017 , we did no t recognize any expense related to shared costs with AbbVie. During the three and six months ended June 30, 2016 , we recognized an expense of $3.3 million and $7.6 million , respectively, in research and development expense related to our portion of the shared costs. We and AbbVie shared operational responsibility and decision making authority for commercialization of Duvelisib Products in the United States. Prior to commercialization and regulatory approval, we recognized the cost of manufacturing as a component of research and development and the cost of commercialization as a component of general and administrative expenses. During the three and six months ended June 30, 2016 , we accounted for AbbVie’s share of the costs as a reduction of the related expense or as additional expense. We recognized credits of approximately $0.1 million during each of the three and six months ended June 30, 2016 in research and development expense related to these costs. During the three and six months ended June 30, 2016 , we recognized credits of $1.6 million and $2.6 million , respectively, in general and administrative expense related to these costs. Under the AbbVie Agreement, AbbVie paid us a non-refundable $275 million upfront payment in 2014 and a $130 million milestone payment in November 2015 associated with the completion of enrollment of DYNAMO, our Phase 2 clinical study evaluating the efficacy and safety of duvelisib in patients with refractory indolent non-Hodgkin lymphoma, or iNHL. Of the total $405 million received from AbbVie, we allocated $234.3 million to the license which was recognized as revenue upon receipt of the upfront payment and achievement of the milestone payment. Revenue related to development services and committee services was recognized using the proportionate performance method. On September 23, 2016, the effective date of the AbbVie Agreement termination, we received all rights to the regulatory filings related to duvelisib, our license to AbbVie terminated, and AbbVie granted us an exclusive, perpetual, irrevocable, royalty-free license, under certain patent rights and know-how controlled by AbbVie, to develop, manufacture and commercialize products containing duvelisib, excluding any compound which is covered by patent rights controlled by AbbVie or its affiliates, in oncology indications worldwide. Neither party has any ongoing financial obligation to the other party under the AbbVie Agreement.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following: June 30, 2017 December 31, 2016 (in thousands) Accrued restructuring $ 709 $ 6,920 Accrued compensation and benefits 5,601 5,445 Accrued drug manufacturing costs 218 311 Accrued clinical studies 1,573 7,054 Accrued preclinical studies 59 2 Other 1,739 1,276 Total accrued expenses $ 9,899 $ 21,008

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Leases [Abstract]
Commitments and Contingencies	Commitments and Contingencies We currently lease approximately 61,000 square feet of office space at 784 Memorial Drive, Cambridge, Massachusetts, under a lease agreement, or the Lease, with BHX, LLC, as trustee of 784 Realty Trust, or the Landlord. On September 25, 2014, we entered into the Lease with the Landlord for the lease of office space at 784 Memorial Drive, Cambridge, Massachusetts. The term of the Lease commenced on November 1, 2014 , or the Commencement Date, and was to expire on March 31, 2025 . Pursuant to the Lease, on the Commencement Date we agreed to lease 61,000 square feet of the leased premises. On the Commencement Date, building construction was initiated to suit our then-anticipated future needs. We were responsible for the construction project, including having responsibility to pay for a portion of the structural elements of the building and bearing the risk of cost overruns. As such, we were deemed the owner of the building for accounting purposes, and we recorded the building in our property and equipment balance, although legal ownership remains with the Landlord. Our balance sheet also reflects a financing obligation related to this building. Depreciation on the building and building improvements commenced in June 2015. We divide our payments under the Lease into a portion that is allocated to the financing obligation and a portion that is allocated to the land on which the building is located. The portion of the lease obligation allocated to the land is treated for accounting purposes as an operating lease which commenced in November 2014 and is recorded on a straight-line basis over the initial term of the Lease. Rent expense pertaining to the land was approximately $0.1 million and $0.2 million for each of the three and six month periods ended June 30, 2017 and June 30, 2016 , respectively. On March 27, 2017, we and the Landlord entered into an amendment to the Lease under which we and the Landlord agreed to the early termination of the Lease subject to the satisfaction of specified contingencies, which we refer to as Lease Termination Contingencies, and a termination payment of $5.0 million , which we refer to as the Termination Payment and describe further below. The Lease amendment was extended by entry into a second lease amendment dated May 1, 2017, and a third lease amendment dated May 31, 2017. We refer to the Lease amendment and its extensions as the Lease Amendments. The Lease Termination Contingencies were satisfied on June 15, 2017 and, pursuant to the Lease Amendments, we paid the first installment of the Termination Payment to the Landlord on June 19, 2017 of $4.5 million . The Lease, as amended, will terminate effective August 31, 2017, provided that we pay the final installment of the Termination Payment of $0.5 million to the Landlord on or before August 31, 2017. We provided a security deposit to the Landlord in the form of a letter of credit in the initial amount of $1.0 million , which was reduced by $0.5 million in April 2017. The remaining $0.5 million will be returned to us following the final installment of the termination payment. The $0.5 million remaining under the letter of credit plus the associated bank fee of $15,000 have been included in our accompanying condensed consolidated balance sheets as a current asset titled restricted cash. During the three-month period ended June 30, 2017 , we recorded other expense of $6.9 million which represents the loss incurred to terminate the financing obligation in connection with the August 31, 2017 lease termination. This loss was comprised of: (i) $1.9 million representing the difference between the estimated carrying value of the building and building improvements and the related financing obligation and deferred rent at August 31, 2017; and (ii) the $5.0 million Termination Payment. We prepaid our July rent payment and at June 30, 2017 , our future minimum payment under the Lease is approximately $0.2 million representing the lease payment for August 2017.

Restructuring Activities

Restructuring Activities	6 Months Ended
	Jun. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring Activities	Restructuring Activities In June 2016, we reported the top line data from DYNAMO, a registration-focused Phase 2 monotherapy study evaluating the efficacy and safety of duvelisib in patients with refractory indolent non-Hodgkin lymphoma, or iNHL. The study met its primary endpoint with an overall response rate of 46% , all of which were partial responses, among 129 patients with iNHL. As a result, we commenced the first of four restructurings that were approved by our Board of Directors in order to preserve our resources as we determine future strategic plans. We undertook the second restructuring following the AbbVie Opt-Out and undertook the third and fourth restructurings in connection with progress on our strategic plans to divest duvelisib, ultimately culminating with our entry into the Verastem Agreement. See Note 8 for additional detail on the AbbVie Opt-Out and the Verastem Agreement. We reduced our employee headcount by approximately 75% compared to our employee headcount as of December 31, 2015 as a result of these four restructurings. We have existing severance plans that outline contractual termination benefits. We recognized all contractual severance and benefits outlined in the plan when termination was probable and reasonably estimable in accordance with FASB Accounting Standards Codification Topic 712, Compensation - Nonretirement Postemployment Benefits, during 2016 at the time of each restructuring. In addition to the employee-related costs, during the year ended December 31, 2016, we recorded approximately $1.9 million of expense related to the write-off of prepaid expenses that were not expected to continue and other payments that were due as a result of early terminations. During the year ended December 31, 2016, we also identified and recorded the impairment of approximately $0.4 million in furniture and fixtures and $0.8 million related to a facility lease that was terminated in 2016. The following table summarizes the impact of the 2016 restructuring activities on our operating expenses and payments for the six months ended June 30, 2017 and the current liability remaining on our balance sheet as of June 30, 2017 , in thousands: Amounts accrued at December 31, 2016 Charges incurred during the six months ended June 30, 2017 Amounts paid during the six months ended June 30, 2017 Less non-cash charges during the six months ended June 30, 2017 Amounts accrued at June 30, 2017 (in thousands) Employee severance, benefits and related costs for work force reduction $ 6,892 $ — $ 5,938 $ 245 $ 709 Contract termination, prepaid expense write-offs and other related costs 28 15 43 — — Total restructuring $ 6,920 $ 15 $ 5,981 $ 245 $ 709 During the three and six months ended June 30, 2016 , we recorded $16.6 million of expense related to restructuring activities of which $11.9 million is recorded in research and development expense and $4.7 million is recorded in general and administrative expense. During the year ended December 31, 2016, we recorded $21.2 million of expense related to restructuring activities of which $13.6 million is recorded in research and development expense and $7.6 million is recorded in general and administrative expense. We are obligated to continue to pay the remaining amounts accrued through the third quarter of 2017.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On July 26, 2017, we entered into a third amendment, or the Third Amendment, to our Takeda Agreement. Under the Third Amendment, our obligations to Takeda under our Takeda Agreement to pay royalties with respect to worldwide net sales of products containing or comprised of a selective inhibitor of PI3K gamma, including but not limited to IPI-549, are terminated. In consideration for such termination, we concurrently executed a convertible promissory note, or the Note, pursuant to which we are obligated to pay Takeda, or its designated affiliate, the principal amount of $6.0 million together with interest accruing at a rate of 8% per annum on or before July 26, 2018 in cash or in shares of Infinity common stock, at the election of Takeda. The share payment price would be equal to the average closing price of Infinity common stock for the 20 days prior to the payment date. We have the right to prepay the Note, in whole or in part, without penalty and any amounts owed under the Note would become immediately due and payable in the event of a change of control of the Infinity, as defined in the Note. Additionally, any unpaid amounts may become immediately due and payable upon customary events of default, as defined in the Note. In the event that Takeda elects to receive one or more payments in shares of Company common stock, or Share Repayment, we have agreed to file one or more registration statements on Form S-3 with the SEC to register for resales the shares of common stock issuable upon repayment of the Note, or Repayment Shares, within 45 days after each Share Repayment. In the event that we propose to make an underwritten offering of our common stock, subject to certain limitations, Takeda will have “piggyback” registration rights, which require us, at the election of Takeda, to cause to be included in such underwritten offering, any Repayment Shares then held by Takeda. We are currently assessing the accounting implications of the Third Amendment.

Significant Accounting Polici18

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Segment Information	Segment Information We operate in one business segment, which focuses on drug development. We make operating decisions based upon the performance of the enterprise as a whole and utilize our consolidated financial statements for decision making. All of our revenues since September 2006 have been generated under collaboration agreements.
Basic and Diluted Net Income (Loss) per Common Share	Basic and Diluted Net Income (Loss) per Common Share Basic net income (loss) per share is based upon the weighted average number of common shares outstanding during the period, excluding restricted stock that has been issued but has not yet vested. Diluted net income (loss) per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options and the exercise of outstanding warrants (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method) and the vesting of restricted shares of common stock. In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. The two-class method is used for outstanding warrants as such warrants are considered to be participating securities, and such method is more dilutive than the treasury stock method.
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2014-9, Revenue from Contracts with Customers , or ASU No. 2014-9, which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. ASU No. 2014-9 was originally effective for interim and annual periods beginning after December 15, 2016. In August 2015, the FASB issued a one-year deferral of the effective date of this standard to annual reporting periods, and interim reporting periods within those years, beginning after December 15, 2017. Entities are allowed to adopt the standard as of the original effective date. The standard allows for two transition methods - full retrospective, in which the standard is applied to each prior reporting period presented or modified retrospective, in which the cumulative effect of initially applying the standard recognized at the date of initial adoption. We expect to elect the modified retrospective approach and are continuing to evaluate the impact that ASU No. 2014-09 may have on our consolidated financial statements in connection with collaboration and license agreements. In November 2016, FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash, or ASU No. 2016-18. ASU No. 2016-18 provides guidance on the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. Under ASU No. 2016-18, the statement of cash flows shall explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Amounts generally described as restricted cash and cash equivalents should now be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statements of cash flows. The amendments of this ASU are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. Other than the revised statement of cash flows presentation, the adoption of ASU No. 2016-18 is not expected to have an impact on our condensed consolidated financial statements. Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU No. 2016-09, which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification of cash flows. We adopted ASU No. 2016-09 as of January 1, 2017. Under the new standard, all excess tax benefits and tax deficiencies are recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards are treated as discrete items in the reporting period in which they occur. We applied the modified retrospective adoption approach upon adoption of the standard, and prior periods have not been adjusted. As a result, we established a net operating loss deferred tax asset of $7.5 million to account for prior period excess tax benefits through retained earnings, and an offsetting valuation allowance of $7.5 million through retained earnings, because it is not more likely than not that the deferred tax asset will be realized due to historical and expected future losses. We elected to recognize forfeitures related to employee share-based payments as they occur. There was no material impact on our financial statements as a result of the adoption of this guidance.

Significant Accounting Polici19

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from Earnings Per Share	The following outstanding shares of common stock equivalents were excluded from the computation of net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock options 8,120,150 9,194,421 8,120,150 9,128,732 Warrants (excluded from treasury stock method) 1,000,000 1,000,000 1,000,000 1,000,000 Unvested restricted stock 663,811 — 663,811 —
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted earnings (loss) per common share were determined as follows: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands, except share and per share amounts) Basic Net income (loss) $ (16,954 ) $ 52,991 $ (27,429 ) $ 12,327 Undistributed earnings allocated to warrants — (1,051 ) — (245 ) Net income (loss) $ (16,954 ) $ 51,940 $ (27,429 ) $ 12,082 Weighted average common shares outstanding 50,455,832 49,437,062 50,439,682 49,388,475 Basic earnings (loss) per common share $ (0.34 ) $ 1.05 $ (0.54 ) $ 0.24 Diluted Net income (loss) $ (16,954 ) $ 52,991 $ (27,429 ) $ 12,327 Undistributed earnings allocated to warrants — (1,051 ) — (245 ) Net income (loss) $ (16,954 ) $ 51,940 $ (27,429 ) $ 12,082 Weighted average common shares outstanding 50,455,832 49,437,062 50,439,682 49,388,475 Effect of dilutive options — 2,475 — 11,451 Weighted average common shares outstanding assuming dilution 50,455,832 49,439,537 50,439,682 49,399,926 Diluted earnings (loss) per common share $ (0.34 ) $ 1.05 $ (0.54 ) $ 0.24

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense, Related to All Equity Awards	Total stock-based compensation expense related to all equity awards for the three and six months ended June 30, 2017 and 2016 was comprised of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands) Research and development $ 394 $ 2,090 $ 1,101 $ 3,966 General and administrative 1,603 1,723 2,703 3,562 Total stock-based compensation expense $ 1,997 $ 3,813 $ 3,804 $ 7,528
Black-Scholes Valuation Model, Weighted-Average Assumptions for Stock Options	For the three and six months ended June 30, 2017 and 2016 , the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Risk-free interest rate 1.8 % 1.3 % 1.9 % 1.8 % Expected annual dividend yield — — — — Expected stock price volatility 90.0 % 86.7 % 90.0 % 73.0 % Expected term of options 5.7 years 4.9 years 5.6 years 5.4 years
Black-Scholes Valuation Model, Weighted-Average Assumptions for Employee Stock Purchase Plan	For the six months ended June 30, 2017 and June 30, 2016 , the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions: Six Months Ended June 30, 2017 2016 Risk-free interest rate 1.2 % 0.8 % Expected annual dividend yield — — Expected stock price volatility 101.8 % 63.5 % Expected term 1.3 years 1.3 years

Cash, Cash Equivalents and Av21

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	6 Months Ended
	Jun. 30, 2017
Cash and Cash Equivalents [Abstract]
Summary of Cash, Cash Equivalents and Available-for-sale Securities	The following is a summary of cash, cash equivalents and available-for-sale securities: June 30, 2017 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 66,197 $ — $ — $ 66,197 Total cash and cash equivalents $ 66,197 $ — $ — $ 66,197 December 31, 2016 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 74,060 $ — $ — $ 74,060 Available-for-sale securities: U.S. Treasury securities due in one year or less 6,753 — (1 ) 6,752 U.S. government-sponsored enterprise obligations due in one year or less 11,254 — (2 ) 11,252 Total available-for-sale securities 18,007 — (3 ) 18,004 Total cash, cash equivalents and available-for-sale securities $ 92,067 $ — $ (3 ) $ 92,064

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table provides the assets carried at fair value measured on a recurring basis as of June 30, 2017 and December 31, 2016 : Level 1 Level 2 (in thousands) June 30, 2017 Assets: Cash and cash equivalents $ 66,197 $ — Total $ 66,197 $ — December 31, 2016 Assets: Cash and cash equivalents $ 61,008 $ 13,052 U.S. Treasury securities — 6,752 U.S. government-sponsored enterprise obligations — 11,252 Total $ 61,008 $ 31,056

Prepaid Expenses and Other Cu23

Prepaid Expenses and Other Current Assets (Tables)	6 Months Ended
	Jun. 30, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following: June 30, 2017 December 31, 2016 (in thousands) Prepaid expenses $ 1,492 $ 3,336 Other current assets 484 5,023 Value-added tax receivable 89 85 Total prepaid expenses and other current assets $ 2,065 $ 8,444

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: June 30, 2017 December 31, 2016 (in thousands) Accrued restructuring $ 709 $ 6,920 Accrued compensation and benefits 5,601 5,445 Accrued drug manufacturing costs 218 311 Accrued clinical studies 1,573 7,054 Accrued preclinical studies 59 2 Other 1,739 1,276 Total accrued expenses $ 9,899 $ 21,008

Restructuring Activities (Table

Restructuring Activities (Tables)	6 Months Ended
	Jun. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table summarizes the impact of the 2016 restructuring activities on our operating expenses and payments for the six months ended June 30, 2017 and the current liability remaining on our balance sheet as of June 30, 2017 , in thousands: Amounts accrued at December 31, 2016 Charges incurred during the six months ended June 30, 2017 Amounts paid during the six months ended June 30, 2017 Less non-cash charges during the six months ended June 30, 2017 Amounts accrued at June 30, 2017 (in thousands) Employee severance, benefits and related costs for work force reduction $ 6,892 $ — $ 5,938 $ 245 $ 709 Contract termination, prepaid expense write-offs and other related costs 28 15 43 — — Total restructuring $ 6,920 $ 15 $ 5,981 $ 245 $ 709

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Oct. 29, 2016	Jun. 30, 2016	Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accumulated deficit	$ 653,118,000	$ 625,689,000
Cash and cash equivalents	66,197,000	$ 74,060,000		$ 122,351,000	$ 188,170,000
Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Required payment upon completion of study	6,000,000		$ 6,000,000
Required payment upon approval of application	$ 22,000,000		$ 22,000,000

Significant Accounting Polici27

Significant Accounting Policies - Additional Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017Segment	Jan. 01, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments | Segment	1
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net operating loss, deferred tax assets		$ 7.5
Deferred tax assets, valuation allowance		$ 7.5

Significant Accounting Polici28

Significant Accounting Policies - Antidilutive Securities Excluded From Computation of Earnings Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	8,120,150	9,194,421	8,120,150	9,128,732
Warrants (excluded from treasury stock method)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,000,000	1,000,000	1,000,000	1,000,000
Unvested restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	663,811,000	0	663,811,000	0

Significant Accounting Polici29

Significant Accounting Policies - Basic and Diluted Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic
Net income (loss)	$ (16,954)	$ 52,991	$ (27,429)	$ 12,327
Net income (loss)	$ (16,954)	$ 51,940	$ (27,429)	$ 12,082
Weighted average common shares outstanding (in shares)	50,455,832	49,437,062	50,439,682	49,388,475
Basic earnings (loss) per common share (in dollars per share)	$ (0.34)	$ 1.05	$ (0.54)	$ 0.24
Diluted
Net income (loss)	$ (16,954)	$ 52,991	$ (27,429)	$ 12,327
Net income (loss)	$ (16,954)	$ 51,940	$ (27,429)	$ 12,082
Weighted average common shares outstanding (in shares)	50,455,832	49,437,062	50,439,682	49,388,475
Effect of dilutive options (in shares)	0	2,475	0	11,451
Weighted average common shares outstanding assuming dilution (in shares)	50,455,832	49,439,537	50,439,682	49,399,926
Diluted earnings (loss) per common share (in dollars per share)	$ (0.34)	$ 1.05	$ (0.54)	$ 0.24
Warrants (excluded from treasury stock method)
Basic
Undistributed earnings allocated to warrants	$ 0	$ (1,051)	$ 0	$ (245)
Diluted
Undistributed earnings allocated to warrants	$ 0	$ (1,051)	$ 0	$ (245)

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,997	$ 3,813	$ 3,804	$ 7,528
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	394	2,090	1,101	3,966
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,603	$ 1,723	$ 2,703	$ 3,562

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options	$ 7,500		$ 7,500
Share-based compensation expense	$ 1,997	$ 3,813	$ 3,804	$ 7,528
Stock options exercised (in shares)			0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, weighted-average recognition period, stock options			1 year 3 months 18 days
Stock options granted (in shares)			4,708,500	1,617,472
Stock options granted, weighted average fair value (in dollars per share)			$ 1.17	$ 3.75
Stock options granted, weighted average exercise price (in dollars per share)			$ 1.61	6.14
Unvested restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)			0
Shares of restricted stock forfeited (in shares)			133,300
Shares of restricted stock vested (in shares)			0
Shares issued and unvested (in shares)	663,811		663,811
Share-based compensation expense	$ 300
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share of ESPP granted (in dollars per share)			$ 0.98	$ 2.91

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options and Employee Stock Purchase Plan (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.80%	1.30%	1.90%	1.80%
Expected annual dividend yield	0.00%	0.00%	0.00%	0.00%
Expected stock price volatility	90.00%	86.70%	90.00%	73.00%
Expected term of options	5 years 8 months 18 days	4 years 10 months 18 days	5 years 7 months 18 days	5 years 4 months 18 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.20%	0.80%
Expected annual dividend yield			0.00%	0.00%
Expected stock price volatility			101.80%	63.50%
Expected term of options			1 year 3 months 1 day	1 year 3 months 10 days

Cash, Cash Equivalents and Av33

Cash, Cash Equivalents and Available-for-Sale Securities - Summary of Cash, Cash Equivalents and Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 66,197	$ 74,060
Cash and cash equivalents, gross unrealized gains	0	0
Cash and cash equivalents, gross unrealized losses	0	0
Cash and cash equivalents, estimated fair value	$ 66,197	74,060	$ 122,351	$ 188,170
Total available-for-sale securities		18,007
Total available-for-sale securities, gross unrealized gains		0
Total available-for-sale securities, gross unrealized losses		(3)
Total available-for-sale securities, estimated fair value		18,004
Total cash, cash equivalents and available-for-sale securities		92,067
Total cash, cash equivalents and available-for-sale securities, gross unrealized gains		0
Total cash, cash equivalents and available-for-sale securities, gross unrealized losses		(3)
Total cash, cash equivalents and available-for-sale securities, estimated fair value		92,064
U.S. Treasury securities due in one year or less
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, due in one year or less, cost		6,753
Available-for-sale securities, due in one year or less, gross unrealized gains		0
Available-for-sale securities, due in one year or less, gross unrealized losses		(1)
Available-for-sale securities, due in one year or less, estimated fair value		6,752
U.S. government-sponsored enterprise obligations due in one year or less
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, due in one year or less, cost		11,254
Available-for-sale securities, due in one year or less, gross unrealized gains		0
Available-for-sale securities, due in one year or less, gross unrealized losses		(2)
Available-for-sale securities, due in one year or less, estimated fair value		$ 11,252

Cash, Cash Equivalents and Av34

Cash, Cash Equivalents and Available-for-Sale Securities - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash and Cash Equivalents [Abstract]
Available-for-sale securities, realized gains or losses	$ 0	$ 0	$ 0	$ 0
Available-for-sale securities, other-than-temporary impairments	$ 0	$ 0	$ 0	$ 0

Fair Value - Schedule of Assets

Fair Value - Schedule of Assets Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		$ 6,752
U.S. government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		11,252
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 66,197	61,008
Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	66,197	61,008
Level 1 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		0
Level 1 | U.S. government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	31,056
Level 2 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	13,052
Level 2 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		6,752
Level 2 | U.S. government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, due in one year or less, estimated fair value		$ 11,252

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Transfers of assets or liabilities between Level 1 and Level 2	$ 0
Available-for-sale securities		$ 18,004,000
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	$ 0	$ 0

Prepaid Expenses and Other Cu37

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 1,492	$ 3,336
Other current assets	484	5,023
Value-added tax receivable	89	85
Total prepaid expenses and other current assets	$ 2,065	$ 8,444

Collaborations - Additional Inf

Collaborations - Additional Information (Details)	Oct. 29, 2016USD ($)Product	Jun. 24, 2016	Sep. 30, 2016Product	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2014USD ($)	Nov. 30, 2015USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development				$ 3,901,000	$ 52,947,000	$ 7,940,000	$ 92,135,000
Collaboration revenue				0	9,467,000	0	18,723,000
Gain from written notice termination				0	112,216,000	$ 0	112,216,000
Number of distinct product candidates | Product			1
Percent of revenue obligated to pay for qualifying transaction			50.00%
Current
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Prior written notice for termination term period						180 days
Prior written notice for termination on breach of agreement by other party period						75 days
Prior written notice for termination on non payment by other party period						30 days
Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Approval and commercialization cost of distinct products payable (up to)				165,000,000		$ 165,000,000
Maximum | Current
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development cost of distinct product candidates (up to)				5,000,000		$ 5,000,000
Percent of royalty on net sale						11.00%
Minimum | Current
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percent of royalty on net sale						7.00%
Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of licensed products | Product	1
Receivable				100,000		$ 100,000
Required payment upon completion of study	$ 6,000,000			6,000,000		6,000,000
Required payment upon approval of application	$ 22,000,000			22,000,000		22,000,000
Payment in lieu of cash, percent of common stock shares used in calculation	102.50%
Average share price following milestone achievement, number of days	20 days
Royalty expiration period following first commercial sale of licensed product	10 years
Reduction of royalty percentage on sales of non-patent regulatory exclusivity, percentage	50.00%
Reduction of royalty percentage on third-party payments or patent litigation, percentage	50.00%
Reduction cap of royalty percentage on third-party payments or patent litigation, percentage	50.00%
Prior written notice for termination term period	180 days
Verastem Agreement | Mundipharma
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty percentage on sales, reimbursement of research and development, percentage	4.00%
Verastem Agreement | Trailing Mundipharma
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reduction of royalty percentage on sales of non-patent regulatory exclusivity, percentage	50.00%
Reduction of royalty percentage on third-party payments or patent litigation, percentage	50.00%
Reduction, royalty percentage on sales, reimbursement of research and development upon completion, percentage	1.00%
Verastem Agreement | Trial Closure
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum for clinical study shutdown costs	$ 4,500,000
AbbVie Opt-Out
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Prior written notice for termination term period		90 days
AbbVie Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement upfront payments received								$ 275,000,000
Collaborative agreement upfront and milestone payments received									$ 405,000,000
AbbVie Agreement | License
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue									234,300,000
AbbVie Agreement | Current
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development				0	3,300,000	$ 0	7,600,000
Research and development, medical affairs					100,000		100,000
Reduction in general and administrative expenses					$ 1,600,000		$ 2,600,000
Milestone payment amount									$ 130,000,000
AbbVie Agreement | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development				$ 667,000,000

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued restructuring	$ 709	$ 6,920
Accrued compensation and benefits	5,601	5,445
Accrued drug manufacturing costs	218	311
Accrued clinical studies	1,573	7,054
Accrued preclinical studies	59	2
Other	1,739	1,276
Total accrued expenses	$ 9,899	$ 21,008

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands	Jun. 19, 2017USD ($)	Jun. 15, 2017USD ($)	Mar. 27, 2017USD ($)	Sep. 25, 2014USD ($)ft²	Jun. 30, 2017USD ($)ft²	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)ft²	Jun. 30, 2016USD ($)	Apr. 30, 2017USD ($)
Leases Of Lessee Disclosure [Line Items]
Other expense					$ 6,882	$ 0	$ 6,882	$ 0
Loss on termination of lease					1,900		1,882	0
Lease Agreements
Leases Of Lessee Disclosure [Line Items]
Lease commencement date				Nov. 1, 2014
784 Memorial Drive Premises
Leases Of Lessee Disclosure [Line Items]
Termination payment			$ 5,000
Termination payment, installment one, payment	$ 4,500
Termination payment, installment two		$ 500
Letter of credit outstanding, amount				$ 1,000	500		500
Letter of credit reduction									$ 500
Letter of credit, banking fees				$ 15
Total minimum lease payments					$ 200		$ 200
784 Memorial Drive Premises | Lease Agreements
Leases Of Lessee Disclosure [Line Items]
Area of premises leased under lease agreement | ft²				61,000	61,000		61,000
790 Memorial Drive, or the 790 Premises
Leases Of Lessee Disclosure [Line Items]
Lease expiration date				Mar. 31, 2025
Land
Leases Of Lessee Disclosure [Line Items]
Lease rent expense					$ 100	$ 100	$ 200	$ 200

Restructuring Activities - Addi

Restructuring Activities - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2016restructuringPatient	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Restructuring Cost and Reserve [Line Items]
Research and development, study response rate	46.00%
Research and development, number of research participants with a certain condition | Patient	129
Number of approved strategic restructurings | restructuring	4
Asset impairment charges					$ 800
Expense related to restructuring activities		$ 16,600	$ 15	$ 16,600	21,200
Research and Development Expense
Restructuring Cost and Reserve [Line Items]
Expense related to restructuring activities		11,900		11,900	13,600
General and Administrative Expense
Restructuring Cost and Reserve [Line Items]
Expense related to restructuring activities		$ 4,700		$ 4,700	7,600
Furniture and Fixtures
Restructuring Cost and Reserve [Line Items]
Asset impairment charges					400
Contract Termination
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs, write off of prepaid expenses					$ 1,900
Expense related to restructuring activities			$ 15
June 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Headcount reduction percentage	75.00%

Restructuring Activities - Summ

Restructuring Activities - Summary of Restructuring Costs (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Amounts accrued at December 31, 2016		$ 6,920
Charges incurred during the six months ended June 30, 2017	$ 16,600	15	$ 16,600	$ 21,200
Amounts paid during the six months ended June 30, 2017		5,981
Less non-cash charges during the six months ended June 30, 2017		245
Amounts accrued at June 30, 2017		709		6,920
Employee severance, benefits and related costs for work force reduction
Restructuring Reserve [Roll Forward]
Amounts accrued at December 31, 2016		6,892
Charges incurred during the six months ended June 30, 2017		0
Amounts paid during the six months ended June 30, 2017		5,938
Less non-cash charges during the six months ended June 30, 2017		245
Amounts accrued at June 30, 2017		709		6,892
Contract termination, prepaid expense write-offs and other related costs
Restructuring Reserve [Roll Forward]
Amounts accrued at December 31, 2016		28
Charges incurred during the six months ended June 30, 2017		15
Amounts paid during the six months ended June 30, 2017		43
Less non-cash charges during the six months ended June 30, 2017		0
Amounts accrued at June 30, 2017		$ 0		$ 28

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - Convertible Notes Payable - Takeda Agreement - Subsequent Event $ in Millions	Jul. 26, 2017USD ($)payment
Subsequent Event [Line Items]
Short-term convertible debt | $	$ 6
Stated interest rate	8.00%
Days prior to the payment date, share payment price	20 days
Number of payments in shares, if elect to receive payment in shares (or more)	1
Number of registration statements, if elect to receive payment in shares (or more)	1
Number of days to file registration statements, if elect to receive payment in shares	45 days