Infinity Pharmaceuticals (INFIQ) 10-Q 7 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 01, 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	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)		56,850,548

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 49,165	$ 34,607
Available-for-sale securities	0	23,002
Prepaid expenses and other current assets	1,273	777
Total current assets	50,438	58,386
Property and equipment, net	103	219
Other assets	725	748
Total assets	51,266	59,353
Current liabilities:
Accounts payable	767	459
Accrued expenses	4,912	5,136
Note payable (note 8)	0	6,000
Total current liabilities	5,679	11,595
Other liabilities	31	28
Total liabilities	5,710	11,623
Commitments and contingencies
Stockholders’ equity:
Preferred Stock, $0.001 par value; 1,000,000 shares authorized, no shares issued and outstanding at June 30, 2018 and December 31, 2017	0	0
Common Stock, $0.001 par value; 100,000,000 shares authorized; 56,833,649 and 50,761,039 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	57	51
Additional paid-in capital	729,432	715,213
Accumulated deficit	(683,933)	(667,519)
Accumulated other comprehensive loss	0	(15)
Total stockholders’ equity	45,556	47,730
Total liabilities and stockholders’ equity	$ 51,266	$ 59,353

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
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)	56,833,649	50,761,039
Common Stock, shares outstanding (in shares)	56,833,649	50,761,039

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating expenses:
Research and development	$ 3,749	$ 3,901	$ 9,660	$ 7,940
General and administrative	3,386	6,205	6,992	12,642
Total operating expenses	7,135	10,106	16,652	20,582
Loss from operations	(7,135)	(10,106)	(16,652)	(20,582)
Other income (expense):
Investment and other income	172	334	331	637
Interest expense	0	(300)	(93)	(602)
Other expense (note 11)	0	(6,882)	0	(6,882)
Total other income (expense)	172	(6,848)	238	(6,847)
Net loss	$ (6,963)	$ (16,954)	$ (16,414)	$ (27,429)
Basic and diluted loss per common share (in dollars per share)	$ (0.12)	$ (0.34)	$ (0.30)	$ (0.54)
Basic and diluted weighted average number of common shares outstanding (in shares)	55,966,910	50,455,832	53,936,520	50,439,682
Other comprehensive loss:
Net unrealized holding gains on available-for-sale securities arising during the period	$ 11	$ 0	$ 15	$ 3
Comprehensive loss	$ (6,952)	$ (16,954)	$ (16,399)	$ (27,426)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net loss	$ (16,414)	$ (27,429)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	116	1,384
Stock-based compensation, including 401(k) match	1,728	3,804
Non-cash adjustment to financing obligation	0	1,882
Other, net	176	8
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(473)	6,391
Accounts payable, accrued expenses and other liabilities	786	(12,922)
Net cash used in operating activities	(14,081)	(26,882)
Investing activities
Purchases of available-for-sale securities	(5,744)	0
Proceeds from maturities of available-for-sale securities	28,790	18,000
Net cash provided by investing activities	23,046	18,000
Financing activities
Proceeds from common stock sales facility, net of issuance costs	9,355	0
Proceeds from issuances of common stock, net	238	70
Repayment of note payable	(4,000)	0
Payments on financing obligation	0	(218)
Net cash provided by (used in) financing activities	5,593	(148)
Net increase (decrease) in cash, cash equivalents and restricted cash	14,558	(9,030)
Cash, cash equivalents and restricted cash at beginning of period	34,607	75,742
Cash, cash equivalents and restricted cash at end of period	49,165	66,712
Supplemental cash flow information
Cash paid for interest	0	602
Supplemental schedule of noncash activities
Issuance of common stock for repayment of note payable, including interest	2,301	0
Issuance of common stock for compensation	$ 493	$ 0

Organization

Organization	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Infinity Pharmaceuticals, Inc., is an innovative biopharmaceutical company dedicated to developing 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, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	2. 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, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2018 . The information presented in the condensed consolidated financial statements and related footnotes at June 30, 2018 , and for the three and six months ended June 30, 2018 and 2017 , is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2017 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, 2017 filed with the U.S. Securities and Exchange Commission, or SEC, on March 15, 2018, which we refer to as our 2017 Annual Report on Form 10-K. Liquidity As of June 30, 2018 , we had cash and cash equivalents of $49.2 million . We have primarily incurred operating losses since inception and have relied on our ability to fund our operations through collaboration and license arrangements and through the sale of stock. We expect to continue to spend significant resources to fund the development and potential commercialization of IPI-549, our sole clinical stage product candidate, an orally administered immune-oncology product candidate that selectively inhibits the enzyme phosphoinositide-3 kinase gamma, or PI3K gamma, and to incur significant operating losses for the foreseeable future. In the absence of additional funding or business development activities, we believe that our existing cash and cash equivalents will be adequate to satisfy our forecasted operating needs through the third quarter of 2019 . This projected cash runway does not assume the receipt of the future potential $22.0 million contingent payment in cash or stock from Verastem, Inc., or Verastem (see Note 8 ). 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, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	3. Significant Accounting Policies Our significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in our 2017 Annual Report on Form 10-K, except as noted below with respect to our revenue recognition accounting policies within “Recently Adopted Accounting Pronouncements.” 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 Loss per Common Share Basic net 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 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 this method is more dilutive than the treasury stock method. The following outstanding shares of common stock equivalents were excluded from the computation of net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive: At June 30, 2018 2017 Stock options 8,109,232 8,120,150 Warrants (excluded from treasury stock method) 1,000,000 1,000,000 Unvested restricted stock — 663,811 New Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases, or ASU No. 2016-02 , which requires lessees to recognize the assets and liabilities arising from leases on the balance sheet. ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the method of adoption and the potential impact that ASU No. 2016-02 may have on our financial position and results of operations. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting, or ASU No. 2018-07 , which expands the scope of Accounting Standard Codification, or ASC, Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. ASU No. 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the potential impact that ASU No. 2018-07 may have on our financial position and results of operations. Recently Adopted Accounting Pronouncements Effective January 1, 2018, we adopted FASB ASC Topic 606, Revenue from Contracts with Customers, or ASC 606. 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. 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 is recognized at the date of initial adoption. We elected the modified retrospective approach and applied it to contracts not completed at the date of adoption. Therefore, comparative prior periods have not been adjusted. The adoption of the standard did not have a material impact on our financial position and results of operations when applied to our two out-licensing arrangements. See Note 8 for additional details on these two arrangements. We did not recognize any revenue during the three and six months ended June 30, 2018 and 2017. The principles in the new standard are applied using a five-step model: 1) identify the customer contract; 2) identify the contract’s performance obligations; 3) determine the transaction price; 4) allocate the transaction price to the performance obligations; and 5) recognize revenue when or as a performance obligation is satisfied. We evaluate all promised goods and services within a customer contract and determine which of those are separate performance obligations. This evaluation includes an assessment of whether the good or service is capable of being distinct and whether the good or service is separable from other promises in the contract. When a performance obligation is satisfied, we recognize as revenue the amount of the transaction price, excluding estimates of variable consideration that are constrained, that is allocated to that performance obligation. For contracts that contain variable consideration, such as milestone payments, we estimate the amount of variable consideration by using either the expected value method or the most likely amount method. In making this assessment, we evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the milestone. We re-evaluate the probability of achievement of such milestones and any related constraint each reporting period. We will include variable consideration, without constraint, in the transaction price to the extent 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. We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories in the period the sales occur under the sales- and usage-based royalty exception when the sole or predominate item to which the royalty relates is a license to intellectual property. We have not recognized any royalty revenue to date. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities , or ASU No. 2016-01, which 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 any changes in fair value recognized in a company's results of operations. 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. We adopted ASU No. 2016-01 as of January 1, 2018. The adoption of ASU No. 2016-01 did not have an impact on our condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , or ASU No. 2016-15, which clarifies classification of certain cash receipts and cash payments on the statement of cash flows to reduce existing diversity in practice. We adopted ASU No. 2016-15 as of January 1, 2018. The adoption of ASU No. 2016-15 did not have a material impact on our condensed consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash, or ASU No. 2016-18, which provides guidance on the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. Under the new standard, the statement of cash flows explains 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 restricted cash equivalents are now included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown in the statements of cash flows. We adopted ASU No. 2016-18 as of January 1, 2018 on a retrospective basis. We have no restricted cash equivalents. The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in our condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 consisted of the following balances from our condensed consolidated balance sheets: Six Months Ended June 30, 2018 Six Months Ended June 30, 2017 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 34,607 $ 49,165 $ 74,060 $ 66,197 Restricted cash — — 1,152 515 Restricted cash, less current portion — — 530 — Cash, cash equivalents and restricted cash per statement of cash flows $ 34,607 $ 49,165 $ 75,742 $ 66,712 In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation: Scope of Modification Accounting , or ASU No. 2017-09, which clarifies when changes to the terms and conditions of a share-based payment award must be accounted for as modifications. The new guidance will result in fewer changes to the terms of an award being accounted for as modifications and reduce diversity in practice for when changes are accounted for as modifications. It does not change the accounting for modifications. We adopted ASU No. 2017-09 as of January 1, 2018, using a prospective approach to awards modified on or after the adoption date, and adoption did not have an impact on our financial statement presentation or disclosures. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , which allowed SEC registrants to record provisional amounts in earnings for the year ended December 31, 2017 due to the complexities involved in accounting for the enactment of the Tax Cuts and Jobs Act of 2017, or the Act. We recognized the estimated income tax effects of the Act in our consolidated financial statements and accompanying footnotes included in our 2017 Annual Report on Form 10-K in accordance with SEC Staff Accounting Bulletin No. 118. The final impact may differ from the provisional amount due to, among other things, changes in interpretations and assumptions we have made thus far and the issuance of additional regulatory or other guidance.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	4. Stock-Based Compensation Total stock-based compensation expense related to all equity awards for the three and six months ended June 30, 2018 and 2017 was composed of the following: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Research and development $ 124 $ 394 $ 259 $ 1,101 General and administrative 721 1,603 1,469 2,703 Total stock-based compensation expense $ 845 $ 1,997 $ 1,728 $ 3,804 As of June 30, 2018 , we had approximately $3.0 million of total unrecognized compensation cost related to unvested common stock options and awards under our Employee Stock Purchase Plan which is expected to be recognized over a weighted-average period of 1.2 years . Restricted Stock We did no t recognize any stock compensation expense for the three and six months ended June 30, 2018 related to restricted stock. We recognized $0.3 million of stock compensation expense for the three and six 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, 2018 , we granted options to purchase 1,337,750 shares of our common stock at a weighted average fair value of $1.60 per share and a weighted average exercise price of $2.09 per share. 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. For the three and six months ended June 30, 2018 and 2017 , 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, 2018 2017 2018 2017 Risk-free interest rate 2.8 % 1.8 % 2.4 % 1.9 % Expected annual dividend yield — — — — Expected stock price volatility 99.2 % 90.0 % 97.2 % 90.0 % Expected term of options 5.4 years 5.7 years 5.6 years 5.6 years During the six months ended June 30, 2018 , options to purchase 130,000 shares of common stock were exercised, with a weighted-average exercise price of $1.46 .

Cash, Cash Equivalents and Avai

Cash, Cash Equivalents and Available-for-Sale Securities	6 Months Ended
	Jun. 30, 2018
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Available-for-Sale Securities	5. Cash, Cash Equivalents and Available-for-Sale Securities The following is a summary of cash, cash equivalents and available-for-sale securities: June 30, 2018 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 49,165 $ — $ — $ 49,165 Total cash and cash equivalents $ 49,165 $ — $ — $ 49,165 December 31, 2017 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 34,607 $ — $ — $ 34,607 Available-for-sale securities: U.S. Treasury securities due in one year or less 3,497 — (3 ) 3,494 U.S. government-sponsored enterprise obligations due in one year or less 19,520 — (12 ) 19,508 Total available-for-sale securities 23,017 — (15 ) 23,002 Total cash, cash equivalents and available-for-sale securities $ 57,624 $ — $ (15 ) $ 57,609 During the six months ended June 30, 2018 , 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, 2018 and 2017 . There were no other-than-temporary impairments recognized for the three and six months ended June 30, 2018 and 2017 .

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value	6. 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, 2018 and December 31, 2017 . The following table sets forth the assets carried at fair value measured on a recurring basis as of June 30, 2018 and December 31, 2017 : Level 1 Level 2 (in thousands) June 30, 2018 Assets: Cash and cash equivalents $ 49,165 $ — Total $ 49,165 $ — December 31, 2017 Assets: Cash and cash equivalents $ 34,607 $ — U.S. Treasury securities — 3,494 U.S. government-sponsored enterprise obligations — 19,508 Total $ 34,607 $ 23,002 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, 2018 . 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, 2018 . We had no available-for-sale securities that were classified as Level 3 at any point during the six months ended June 30, 2018 or during the year ended December 31, 2017 .

Prepaid expenses and other curr

Prepaid expenses and other current assets	6 Months Ended
	Jun. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses and other current assets	7. Prepaid expenses and other current assets Prepaid expenses and other current assets consist of the following: June 30, 2018 December 31, 2017 (in thousands) Prepaid expenses $ 1,132 $ 563 Other current assets 141 214 Total prepaid expenses and other current assets $ 1,273 $ 777

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	8. Collaborations Takeda In July 2010, we entered into a development and license agreement with Takeda Pharmaceutical Company Limited, which we refer to as Takeda, our PI3K inhibitor program licensor, 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. We refer to the amended and restated development and license agreement, as amended, as the Takeda Agreement. The July 2017 amendment to the Takeda Agreement terminated our obligations to pay royalties to Takeda 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. In consideration for such termination, we concurrently executed a convertible promissory note, which we refer to as the Takeda Note, which obligated us 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 our common stock, at the election of Takeda. The $6.0 million has been included in our accompanying condensed consolidated balance sheets as a current liability titled Note Payable as of December 31, 2017. For the six months ended June 30, 2018 , we recorded $0.1 million of interest expense related to the Takeda Note. On March 12, 2018, we exercised our right to prepay in full the Takeda Note in the principal amount of $6.0 million together with interest of approximately $0.3 million . Takeda elected to receive $4.0 million of such payment in cash and approximately $2.3 million of such payment in shares of our common stock. Pursuant to the terms of the Takeda Note, we issued 1,134,689 shares of common stock, calculated using an average price of $2.028 per share, to Takeda’s designated subsidiary, Millennium Pharmaceuticals, Inc. Verastem On October 29, 2016, we and Verastem, Inc., or 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 Licensed Products, in each case in oncology indications. Upon entry into the Verastem Agreement, Verastem assumed financial responsibility for activities that were part of our ongoing duvelisib program, including a randomized, Phase 3 monotherapy clinical study, which we refer to as the DUO Study, in patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma. Following a 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. We assessed this arrangement in accordance with ASC 606 and concluded that at the date of contract inception this arrangement contained two performance obligations, consisting of the license and transition activities. We satisfied the license at contract inception and transition activities over the transition period which ended in December 2016. On September 6, 2017, Verastem notified us that the DUO Study met certain pre-specified criteria at completion triggering a $6.0 million payment under the Verastem Agreement, which we received in cash on October 13, 2017. On April 9, 2018, Verastem announced that the U.S. Food and Drug Administration, or FDA, had accepted, with priority review, Verastem’s new drug application, or NDA, for approval of duvelisib for the treatment of patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma and accelerated approval for the treatment of relapsed or refractory follicular lymphoma. The FDA target action date for response to the NDA is October 5, 2018. If Verastem receives approval of its NDA for duvelisib, Verastem is required to make a $22.0 million payment to us, in cash or, at Verastem’s election, in whole or in part, in shares of Verastem common stock. As of June 30, 2018 , we did no t recognize revenue related to the $22.0 million payment as it is a variable consideration that is constrained as it depends on regulatory approval. Variable consideration associated with regulatory approvals are generally constrained until those approvals are received as it is outside of our control. As the performance obligations were previously satisfied, the milestone would be recognized as revenue in full in the period in which the milestone is achieved. For any portion of the $22.0 million payment that Verastem elects to pay in shares of Verastem 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 20 -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. On a product-by-product and country-by-country basis, subject to specified conditions, Verastem is also obligated to pay us royalties on worldwide net sales of Licensed Products under the Verastem Agreement ranging from the mid-single digits to the high-single digits, which, if received, we expect to share equally with Takeda. In addition, Verastem is obligated to pay us a royalty of 4% on worldwide net sales of Licensed Products on a product-by-product and country-by-country basis, subject to specified conditions, 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 these royalty obligations 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. PellePharm In June 2013, we entered into a license agreement with PellePharm, Inc., or PellePharm, under which we granted PellePharm exclusive global development and commercialization rights to our hedgehog inhibitor program, including IPI-926, a clinical-stage product candidate. We refer to our license agreement with PellePharm as the PellePharm Agreement and products covered by the PellePharm Agreement as Hedgehog Products. We assessed this arrangement in accordance with ASC 606 and concluded that at the date of contract inception there was only one performance obligation, consisting of the license, which was satisfied at contract inception. Under the PellePharm Agreement, PellePharm is obligated to pay us up to $11.0 million in clinical, regulatory and commercial-based milestone payments through the first commercial sale of a Hedgehog Product. PellePharm is also obligated to pay us up to $37.5 million in success-based milestone payments upon the achievement of certain annual net sales thresholds, as well as a share of certain revenue received by PellePharm in the event that PellePharm sublicenses its rights under the PellePharm Agreement and tiered royalties on annual net sales of Hedgehog Products subject to specified conditions. As of June 30, 2018 , we did no t recognize revenue related to the milestones as they represent variable consideration that is constrained. In making this assessment, we considered numerous factors, including the fact that achievement of the milestones is outside our control and contingent upon the future success of clinical trials, PellePharm’s actions, and the receipt of regulatory approval. As the single performance obligation was previously satisfied, all clinical, regulatory and commercial-based milestones will be recognized as revenue in full in the period in which the constraint is removed. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license granted to PellePharm and therefore are recognized at the later of when the performance obligation is satisfied, or the related sales occur. Arcus On June 25, 2018, we entered into a clinical trial collaboration agreement with Arcus Biosciences, Inc., or Arcus. Under the terms of the agreement, which we refer to as the Arcus Agreement, we and Arcus will evaluate IPI-549 in combination with AB928, Arcus’s dual adenosine receptor antagonist, and AB122, Arcus’s anti-PD-1 antibody, as well as IPI-549 in combination with AB928 and chemotherapy, in patients with triple negative breast cancer or ovarian cancer in four separate cohorts. Expenses related to the four triple-combination cohorts will be split equally between us and Arcus.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Accrued Expenses	9. Accrued Expenses Accrued expenses consist of the following: June 30, 2018 December 31, 2017 (in thousands) Accrued compensation and benefits $ 1,568 $ 2,002 Accrued clinical and development 2,424 1,736 Other 920 1,398 Total accrued expenses $ 4,912 $ 5,136

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Stockholders' Equity	10. Stockholders' Equity In May 2016, we entered into a controlled equity offering sales agreement, or Sales Agreement, with Cantor Fitzgerald & Co., or Cantor Fitzgerald, pursuant to which we may from time to time, at our option, offer and sell shares of our common stock having an aggregate offering price of up to $50.0 million through Cantor Fitzgerald, acting as our sales agent. Cantor Fitzgerald will be entitled to a commission of 3.0% of the aggregate gross proceeds from sales of shares of our common stock under the Sales Agreement. Sales of shares of our common stock under the Sales Agreement may be made by any method permitted by law that is deemed an “at the market” offering as defined in Rule 415 under the Securities Act of 1933, as amended, including sales made through the Nasdaq Global Select Market, on any other existing trading market for our common stock or to or through a market maker. We may also authorize Cantor Fitzgerald to sell shares in privately negotiated transactions. During the six months ended June 30, 2018 , we sold 4,461,893 shares of common stock at a weighted average price per share of $2.18 at-the-market pursuant to the Sales Agreement for $9.4 million in net proceeds. We have no obligation to sell shares of our common stock and cannot provide any assurances that we will issue any additional shares pursuant to the Sales Agreement. We may also suspend the offering of shares of our common stock upon notice to Cantor Fitzgerald and subject to other conditions.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Leases [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies We currently sublease 6,091 square feet of office space at 784 Memorial Drive, Cambridge, Massachusetts. The term of the lease commenced on September 1, 2017 and will expire on August 31, 2019 . From September 1, 2017 through August 31, 2018, the base rent of the lease is $19,796 per month. From September 1, 2018 until the expiration date, the base rent of the lease will be $20,303 per month. In addition to the base rent, we are also responsible for our share of the operating expenses, utility costs and real estate taxes, in accordance with the terms of the lease. At June 30, 2018 , future minimum payments under the lease are approximately $0.3 million . We previously leased approximately 61,000 square feet of office space in Cambridge, Massachusetts, under a lease agreement, or the Lease. 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 reflected a financing obligation related to the building. In 2017, we and the landlord entered into amendments to the Lease to early terminate the Lease subject to the satisfaction of specified contingencies and a termination payment of $5.0 million . The contingencies were satisfied on June 15, 2017 and we paid the first installment of the termination payment to the landlord on June 19, 2017 of $4.5 million and the final installment on August 24, 2017 of $0.5 million . The Lease, as amended, terminated effective August 31, 2017. 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.

Significant Accounting Polici17

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	2. 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, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2018 . The information presented in the condensed consolidated financial statements and related footnotes at June 30, 2018 , and for the three and six months ended June 30, 2018 and 2017 , is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2017 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, 2017 filed with the U.S. Securities and Exchange Commission, or SEC, on March 15, 2018, which we refer to as our 2017 Annual Report on Form 10-K.
Liquidity	Liquidity As of June 30, 2018 , we had cash and cash equivalents of $49.2 million . We have primarily incurred operating losses since inception and have relied on our ability to fund our operations through collaboration and license arrangements and through the sale of stock. We expect to continue to spend significant resources to fund the development and potential commercialization of IPI-549, our sole clinical stage product candidate, an orally administered immune-oncology product candidate that selectively inhibits the enzyme phosphoinositide-3 kinase gamma, or PI3K gamma, and to incur significant operating losses for the foreseeable future. In the absence of additional funding or business development activities, we believe that our existing cash and cash equivalents will be adequate to satisfy our forecasted operating needs through the third quarter of 2019 . This projected cash runway does not assume the receipt of the future potential $22.0 million contingent payment in cash or stock from Verastem, Inc., or Verastem (see Note 8 ). 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.
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 Loss per Common Share	Basic and Diluted Net Loss per Common Share Basic net 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 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 this method is more dilutive than the treasury stock method.
New and Recently Adopted Accounting Pronouncements	New Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases, or ASU No. 2016-02 , which requires lessees to recognize the assets and liabilities arising from leases on the balance sheet. ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the method of adoption and the potential impact that ASU No. 2016-02 may have on our financial position and results of operations. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting, or ASU No. 2018-07 , which expands the scope of Accounting Standard Codification, or ASC, Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. ASU No. 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the potential impact that ASU No. 2018-07 may have on our financial position and results of operations. Recently Adopted Accounting Pronouncements Effective January 1, 2018, we adopted FASB ASC Topic 606, Revenue from Contracts with Customers, or ASC 606. 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. 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 is recognized at the date of initial adoption. We elected the modified retrospective approach and applied it to contracts not completed at the date of adoption. Therefore, comparative prior periods have not been adjusted. The adoption of the standard did not have a material impact on our financial position and results of operations when applied to our two out-licensing arrangements. See Note 8 for additional details on these two arrangements. We did not recognize any revenue during the three and six months ended June 30, 2018 and 2017. The principles in the new standard are applied using a five-step model: 1) identify the customer contract; 2) identify the contract’s performance obligations; 3) determine the transaction price; 4) allocate the transaction price to the performance obligations; and 5) recognize revenue when or as a performance obligation is satisfied. We evaluate all promised goods and services within a customer contract and determine which of those are separate performance obligations. This evaluation includes an assessment of whether the good or service is capable of being distinct and whether the good or service is separable from other promises in the contract. When a performance obligation is satisfied, we recognize as revenue the amount of the transaction price, excluding estimates of variable consideration that are constrained, that is allocated to that performance obligation. For contracts that contain variable consideration, such as milestone payments, we estimate the amount of variable consideration by using either the expected value method or the most likely amount method. In making this assessment, we evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the milestone. We re-evaluate the probability of achievement of such milestones and any related constraint each reporting period. We will include variable consideration, without constraint, in the transaction price to the extent 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. We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories in the period the sales occur under the sales- and usage-based royalty exception when the sole or predominate item to which the royalty relates is a license to intellectual property. We have not recognized any royalty revenue to date. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities , or ASU No. 2016-01, which 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 any changes in fair value recognized in a company's results of operations. 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. We adopted ASU No. 2016-01 as of January 1, 2018. The adoption of ASU No. 2016-01 did not have an impact on our condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments , or ASU No. 2016-15, which clarifies classification of certain cash receipts and cash payments on the statement of cash flows to reduce existing diversity in practice. We adopted ASU No. 2016-15 as of January 1, 2018. The adoption of ASU No. 2016-15 did not have a material impact on our condensed consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash, or ASU No. 2016-18, which provides guidance on the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. Under the new standard, the statement of cash flows explains 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 restricted cash equivalents are now included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown in the statements of cash flows. We adopted ASU No. 2016-18 as of January 1, 2018 on a retrospective basis. We have no restricted cash equivalents. The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in our condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 consisted of the following balances from our condensed consolidated balance sheets: Six Months Ended June 30, 2018 Six Months Ended June 30, 2017 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 34,607 $ 49,165 $ 74,060 $ 66,197 Restricted cash — — 1,152 515 Restricted cash, less current portion — — 530 — Cash, cash equivalents and restricted cash per statement of cash flows $ 34,607 $ 49,165 $ 75,742 $ 66,712 In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation: Scope of Modification Accounting , or ASU No. 2017-09, which clarifies when changes to the terms and conditions of a share-based payment award must be accounted for as modifications. The new guidance will result in fewer changes to the terms of an award being accounted for as modifications and reduce diversity in practice for when changes are accounted for as modifications. It does not change the accounting for modifications. We adopted ASU No. 2017-09 as of January 1, 2018, using a prospective approach to awards modified on or after the adoption date, and adoption did not have an impact on our financial statement presentation or disclosures. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , which allowed SEC registrants to record provisional amounts in earnings for the year ended December 31, 2017 due to the complexities involved in accounting for the enactment of the Tax Cuts and Jobs Act of 2017, or the Act. We recognized the estimated income tax effects of the Act in our consolidated financial statements and accompanying footnotes included in our 2017 Annual Report on Form 10-K in accordance with SEC Staff Accounting Bulletin No. 118. The final impact may differ from the provisional amount due to, among other things, changes in interpretations and assumptions we have made thus far and the issuance of additional regulatory or other guidance.

Significant Accounting Polici18

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share	The following outstanding shares of common stock equivalents were excluded from the computation of net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive: At June 30, 2018 2017 Stock options 8,109,232 8,120,150 Warrants (excluded from treasury stock method) 1,000,000 1,000,000 Unvested restricted stock — 663,811
Schedule of Restricted Cash	The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in our condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 consisted of the following balances from our condensed consolidated balance sheets: Six Months Ended June 30, 2018 Six Months Ended June 30, 2017 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 34,607 $ 49,165 $ 74,060 $ 66,197 Restricted cash — — 1,152 515 Restricted cash, less current portion — — 530 — Cash, cash equivalents and restricted cash per statement of cash flows $ 34,607 $ 49,165 $ 75,742 $ 66,712
Schedule of Cash and Cash Equivalents	The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in our condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 consisted of the following balances from our condensed consolidated balance sheets: Six Months Ended June 30, 2018 Six Months Ended June 30, 2017 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 34,607 $ 49,165 $ 74,060 $ 66,197 Restricted cash — — 1,152 515 Restricted cash, less current portion — — 530 — Cash, cash equivalents and restricted cash per statement of cash flows $ 34,607 $ 49,165 $ 75,742 $ 66,712

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
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, 2018 and 2017 was composed of the following: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Research and development $ 124 $ 394 $ 259 $ 1,101 General and administrative 721 1,603 1,469 2,703 Total stock-based compensation expense $ 845 $ 1,997 $ 1,728 $ 3,804
Black-Scholes Valuation Model, Weighted-Average Assumptions for Stock Options	For the three and six months ended June 30, 2018 and 2017 , 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, 2018 2017 2018 2017 Risk-free interest rate 2.8 % 1.8 % 2.4 % 1.9 % Expected annual dividend yield — — — — Expected stock price volatility 99.2 % 90.0 % 97.2 % 90.0 % Expected term of options 5.4 years 5.7 years 5.6 years 5.6 years

Cash, Cash Equivalents and Av20

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	6 Months Ended
	Jun. 30, 2018
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, 2018 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 49,165 $ — $ — $ 49,165 Total cash and cash equivalents $ 49,165 $ — $ — $ 49,165 December 31, 2017 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 34,607 $ — $ — $ 34,607 Available-for-sale securities: U.S. Treasury securities due in one year or less 3,497 — (3 ) 3,494 U.S. government-sponsored enterprise obligations due in one year or less 19,520 — (12 ) 19,508 Total available-for-sale securities 23,017 — (15 ) 23,002 Total cash, cash equivalents and available-for-sale securities $ 57,624 $ — $ (15 ) $ 57,609

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table sets forth the assets carried at fair value measured on a recurring basis as of June 30, 2018 and December 31, 2017 : Level 1 Level 2 (in thousands) June 30, 2018 Assets: Cash and cash equivalents $ 49,165 $ — Total $ 49,165 $ — December 31, 2017 Assets: Cash and cash equivalents $ 34,607 $ — U.S. Treasury securities — 3,494 U.S. government-sponsored enterprise obligations — 19,508 Total $ 34,607 $ 23,002

Prepaid expenses and other cu22

Prepaid expenses and other current assets (Tables)	6 Months Ended
	Jun. 30, 2018
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, 2018 December 31, 2017 (in thousands) Prepaid expenses $ 1,132 $ 563 Other current assets 141 214 Total prepaid expenses and other current assets $ 1,273 $ 777

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following: June 30, 2018 December 31, 2017 (in thousands) Accrued compensation and benefits $ 1,568 $ 2,002 Accrued clinical and development 2,424 1,736 Other 920 1,398 Total accrued expenses $ 4,912 $ 5,136

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017	Oct. 29, 2016
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cash, cash equivalents, and available-for-sale securities	$ 49,200,000	$ 57,624,000
Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Required payment upon approval of application	$ 22,000,000		$ 22,000,000

Significant Accounting Polici25

Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018Segmentagreement
Accounting Policies [Abstract]
Number of operating segments | Segment	1
Out-licensing agreements | agreement	2

Significant Accounting Polici26

Significant Accounting Policies - Antidilutive Securities Excluded From Computation of Earnings Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	8,109,232	8,120,150
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
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)	0	663,811

Significant Accounting Polici27

Significant Accounting Policies Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 49,165	$ 34,607	$ 66,197	$ 74,060
Restricted cash	0	0	515	1,152
Restricted cash, less current portion	0	0	0	530
Cash, cash equivalents and restricted cash per statement of cash flows	$ 49,165	$ 34,607	$ 66,712	$ 75,742

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 845	$ 1,997	$ 1,728	$ 3,804
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	124	394	259	1,101
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 721	$ 1,603	$ 1,469	$ 2,703

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options	$ 3,000,000		$ 3,000,000
Unrecognized compensation cost, weighted-average recognition period, stock options			1 year 2 months 5 days
Stock compensation expense	845,000	$ 1,997,000	$ 1,728,000	$ 3,804,000
Stock options exercised (in shares)			130,000
Stock options exercised, weighted average exercise price (in dollars per share)			$ 1.46
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 0	$ 300,000	$ 0	$ 300,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)			1,337,750	4,708,500
Stock options granted, weighted average fair value (in dollars per share)			$ 1.60	$ 1.17
Stock options granted, weighted average exercise price (in dollars per share)			$ 2.09	$ 1.61

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Details) - Stock options	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.80%	1.80%	2.40%	1.90%
Expected annual dividend yield	0.00%	0.00%	0.00%	0.00%
Expected stock price volatility	99.20%	90.00%	97.20%	90.00%
Expected term of options	5 years 4 months 18 days	5 years 8 months 18 days	5 years 7 months 18 days	5 years 7 months

Cash, Cash Equivalents and Av31

Cash, Cash Equivalents and Available-for-Sale Securities - Summary of Cash, Cash Equivalents and Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, cost	$ 49,165	$ 34,607	$ 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	49,165	34,607
Total available-for-sale securities		23,017
Total available-for-sale securities, gross unrealized gains		0
Total available-for-sale securities, gross unrealized losses		(15)
Total available-for-sale securities, estimated fair value		23,002
Total cash and cash equivalents and available-for-sale securities, at cost	$ 49,200	57,624
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		(15)
Total cash, cash equivalents and available-for-sale securities, estimated fair value		57,609
U.S. Treasury securities due in one year or less
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities		3,497
Available-for-sale securities, gross unrealized gains		0
Available-for-sale securities, gross unrealized losses		(3)
Available-for-sale securities, estimated fair value		3,494
U.S. government-sponsored enterprise obligations due in one year or less
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities		19,520
Available-for-sale securities, gross unrealized gains		0
Available-for-sale securities, gross unrealized losses		(12)
Available-for-sale securities, estimated fair value		$ 19,508

Cash, Cash Equivalents and Av32

Cash, Cash Equivalents and Available-for-Sale Securities - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash and Cash Equivalents [Abstract]
Available-for-sale securities, material 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, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		$ 23,002
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		3,494
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		19,508
Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 49,165	34,607
Total	49,165	34,607
Fair Value, Measurements, Recurring [Member] | 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
Fair Value, Measurements, Recurring [Member] | 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
Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total	$ 0	23,002
Fair Value, Measurements, Recurring [Member] | 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		3,494
Fair Value, Measurements, Recurring [Member] | 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		$ 19,508

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
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		$ 23,002,000
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 cu35

Prepaid expenses and other current assets - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 1,132	$ 563
Other current assets	141	214
Total prepaid expenses and other current assets	$ 1,273	$ 777

Collaborations - Additional Inf

Collaborations - Additional Information (Details) - USD ($)	Mar. 12, 2018	Oct. 29, 2016	Jun. 30, 2013	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Sep. 06, 2017	Jul. 31, 2017
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Note payable				$ 0		$ 0		$ 6,000,000
Interest expense				$ 0	$ 300,000	$ 93,000	$ 602,000
Common Stock, shares issued (in shares)				56,833,649		56,833,649		50,761,039
Takeda Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Note payable								$ 6,000,000		$ 6,000,000
Stated interest rate										8.00%
Interest expense						$ 100,000
Common Stock, shares issued (in shares)	1,134,689
Share price (in dollars per share)	$ 2.028
Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Required payment upon completion of study									$ 6,000,000
Required payment upon approval of application		$ 22,000,000		$ 22,000,000		22,000,000
Contracts revenue						0
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
PellePharm Agreement | Hedgehog Products
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contracts revenue						$ 0
Collaborative agreement, total milestone payment amount			$ 11,000,000
Collaborative agreement, additional milestone payments amount, if circumstances met			$ 37,500,000
Convertible Notes Payable | Takeda Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Extinguishment of debt, amount	$ 6,000,000
Interest paid in stock, value	300,000
Repayments of debt	4,000,000
Common Stock | Convertible Notes Payable | Takeda Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Repayments of debt, including interest, noncash	$ 2,300,000
Mundipharma | Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty percentage on sales		4.00%
Trailing Mundipharma | Verastem Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty percentage on sales, reimbursement of research and development upon completion, percentage		1.00%

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 1,568	$ 2,002
Accrued clinical and development	2,424	1,736
Other	920	1,398
Total accrued expenses	$ 4,912	$ 5,136

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - At-The-Market Facility - USD ($)	1 Months Ended	6 Months Ended
	May 31, 2016	Jun. 30, 2018
Subsidiary, Sale of Stock [Line Items]
Consideration received on transaction		$ 9,400,000
Cantor Fitzgerald
Subsidiary, Sale of Stock [Line Items]
Sales agreement, aggregate offering price	$ 50,000,000
Sales agreement, commission percentage	3.00%
Number of shares sold in transaction (in shares)		4,461,893
Weighted average price per share (in dollars per share)		$ 2.18

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Aug. 24, 2017USD ($)	Jun. 19, 2017USD ($)	Mar. 27, 2017USD ($)	Jun. 30, 2018USD ($)ft²	Jun. 30, 2018USD ($)ft²	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)ft²	Jun. 30, 2017USD ($)	Aug. 31, 2019USD ($)	Aug. 31, 2018USD ($)
Leases Of Lessee Disclosure [Line Items]
Termination payment						$ 5,000,000
Other expense					$ 0	6,882,000	$ 0	$ 6,882,000
Loss on termination of lease						$ 1,900,000	0	$ 1,882,000
784 Memorial Drive Premises
Leases Of Lessee Disclosure [Line Items]
Future minimum payment under the lease				$ 300,000	$ 300,000		$ 300,000
Termination payment			$ 5,000,000
Termination payment, installment one, payment		$ 4,500,000
Termination payment, installment two	$ 500,000
Sublease Agreement | 784 Memorial Drive Premises
Leases Of Lessee Disclosure [Line Items]
Area of premises subleased under lease agreement | ft²				6,091	6,091		6,091
Lease commencement date				Sep. 1, 2017
Lease expiration date				Aug. 31, 2019
Sublease Agreement | 784 Memorial Drive Premises | Scenario, Forecast
Leases Of Lessee Disclosure [Line Items]
Monthly base rent expense									$ 20,303	$ 19,796
Lease Agreements | 784 Memorial Drive Premises
Leases Of Lessee Disclosure [Line Items]
Area of premises leased under lease agreement | ft²				61,000	61,000		61,000