Infinity Pharmaceuticals (INFIQ) 10-K 16 Mar 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 05, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	000-31141
Entity Registrant Name	INFINITY PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0655706
Entity Address, Address Line One	1100 Massachusetts Avenue
Entity Address, Address Line Two	Floor 4
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02138
City Area Code	617
Local Phone Number	453-1000
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	INFI
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 34,316,849
Entity Common Stock, Shares Outstanding (in shares)		88,639,741
Documents Incorporated by Reference	Portions of our definitive proxy statement to be filed with the Securities and Exchange Commission no later than April 30, 2021 in connection with our 2021 annual meeting of stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0001113148

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 28,593	$ 22,260
Available-for-sale securities	5,515	20,184
Prepaid expenses and other current assets	1,912	2,137
Total current assets	36,020	44,581
Property and equipment, net	1,710	2,186
Restricted cash, less current portion	165	315
Operating lease right-of-use assets	1,419	1,717
Other assets	5	215
Total assets	39,319	49,014
Current liabilities:
Accounts payable	2,982	1,621
Accrued expenses and other current liabilities	8,065	8,077
Total current liabilities	11,047	9,698
Liability related to sale of future royalties, net, less current portion (note 9)	28,021	29,626
Liability related to sale of future royalties to a related party, net (note 10)	21,559	0
Operating lease liability, less current portion	1,436	1,926
Other liabilities	245	38
Total liabilities	62,308	41,288
Commitments and contingencies
Stockholders’ equity (deficit):
Preferred Stock, $0.001 par value; 1,000,000 shares authorized, no shares issued and outstanding at December 31, 2020 and 2019	0	0
Common Stock, $0.001 par value; 200,000,000 and 100,000,000 shares authorized December 31, 2020 and 2019, respectively; 64,320,244 and 57,077,550 shares issued and outstanding at December 31, 2020 and 2019, respectively	64	57
Additional paid-in capital	743,269	733,486
Accumulated deficit	(766,321)	(725,829)
Accumulated other comprehensive income (loss)	(1)	12
Total stockholders’ equity (deficit)	(22,989)	7,726
Total liabilities and stockholders’ equity	$ 39,319	$ 49,014

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
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)	200,000,000	100,000,000
Common stock, shares issued (in shares)	64,320,244	57,077,550
Common stock, shares outstanding (in shares)	64,320,244	57,077,550

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue:
Total revenues	$ 1,719,000	$ 3,049,000
Operating expenses:
Research and development	26,761,000	27,116,000
General and administrative	12,418,000	14,289,000
Royalty expense (note 12)	1,037,000	7,308,000
Total operating expenses	40,216,000	48,713,000
Loss from operations	(38,497,000)	(45,664,000)
Other income (expense):
Other Nonoperating Income (Expense)	450,000	1,116,000
Interest expense (note 9)	(153,000)	(2,563,000)
Related party interest expense (note 10)	(2,292,000)	0
Total other expense	(1,995,000)	(1,447,000)
Loss before income taxes	(40,492,000)	(47,111,000)
Income tax benefit	0	54,000
Net loss	$ (40,492,000)	$ (47,057,000)
Basic and diluted loss per common share (in dollars per share)	$ (0.68)	$ (0.83)
Basic and diluted weighted average number of common shares outstanding (in shares)	59,857,860	56,983,652
Other comprehensive loss:
Net unrealized holding gains (losses) on available-for-sale securities arising during the period	$ (13,000)	$ 16,000
Comprehensive loss	(40,505,000)	(47,041,000)
Collaboration revenue
Revenue:
Total revenues	0	2,000,000
Royalty revenue
Revenue:
Total revenues	$ 1,719,000	$ 1,049,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (40,492)	$ (47,057)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	483	219
Stock-based compensation	1,456	2,133
Non-cash royalty revenue	(910)	(555)
Non-cash interest expense	153	2,563
Non-cash related party interest expense	2,292	0
Other, net	(106)	(216)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	585	(756)
Operating lease right-of-use asset	298	364
Accounts payable, accrued expenses and other liabilities	882	1,550
Operating lease liability	(380)	225
Net cash used in operating activities	(35,739)	(41,530)
Investing activities
Purchases of property and equipment	(43)	(2,327)
Purchases of available-for-sale securities	(43,006)	(41,864)
Proceeds from maturities of available-for-sale securities	57,680	31,950
Net cash provided by (used in) investing activities	14,631	(12,241)
Financing activities
Proceeds from sale of future royalties to a related party, net	19,572	0
Proceeds from sale of future royalties, net	0	27,618
Proceeds from common stock sales facility, net of issuance costs	7,711	0
Proceeds from issuances of common stock, net	158	112
Net cash provided by financing activities	27,441	27,730
Net increase (decrease) in cash, cash equivalents and restricted cash	6,333	(26,041)
Cash, cash equivalents and restricted cash at beginning of period	22,575	48,616
Cash, cash equivalents and restricted cash at end of period	28,908	22,575
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets
Total cash, cash equivalents and restricted cash	22,575	22,575
Supplemental schedule of noncash activities
Assets acquired under operating lease obligation	0	1,908
Property and equipment in accounts payable and accrued expenses	0	50
Issuance of common stock for compensation	$ 444	$ 0

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2018		56,907,096
Beginning Balance at Dec. 31, 2018	$ 52,459	$ 57	$ 731,178	$ (678,772)	$ (4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		2,188
Exercise of stock options	3		3
Stock-based compensation expense	2,133		2,133
Issuance of common stock, net (in shares)		168,266
Issuance of common stock, net	172		172
Unrealized loss on marketable securities	16				16
Net loss	(47,057)			(47,057)
Ending Balance (in shares) at Dec. 31, 2019		57,077,550
Ending Balance at Dec. 31, 2019	$ 7,726	$ 57	733,486	(725,829)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	46,433	46,433
Exercise of stock options	$ 85		85
Stock-based compensation expense	1,456		1,456
Issuance of common stock, net (in shares)		470,570
Issuance of common stock, net	538		538
Unrealized loss on marketable securities	(13)				(13)
Net loss	(40,492)			(40,492)
Issuance of common stock related to sales facility, net of issuance costs (in shares)		6,725,691
Issuance of common stock related to sales facility, net of issuance costs	7,711	$ 7	7,704
Ending Balance (in shares) at Dec. 31, 2020		64,320,244
Ending Balance at Dec. 31, 2020	$ (22,989)	$ 64	$ 743,269	$ (766,321)	$ (1)

Organization

Organization	12 Months Ended
	Dec. 31, 2020
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 audited, consolidated financial statements, the terms “Infinity,” “we,” “us,” and “our” refer to the business of Infinity Pharmaceuticals, Inc., and its wholly owned subsidiaries.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation These 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 preparation of consolidated financial statements in accordance with generally accepted accounting principles requires our management to make estimates and judgments that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and judgments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions. Segment Information We operate in one business segment, which focuses on drug development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making. Cash Equivalents and Available-For-Sale Securities Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. Treasury securities, and U.S. government-sponsored enterprise obligations. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds, U.S. Treasury securities, and U.S. government-sponsored enterprise obligations., are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods. We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at December 31, 2020 and 2019 as “available-for-sale.” We carry available-for-sale securities at fair value. Unrealized gains and losses on available-for-sale debt securities are reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity. We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in investment and other income. The cost of securities sold is based on the specific identification method. We include in investment income interest and dividends on securities classified as available-for-sale. We conduct periodic reviews to identify and evaluate each available-for-sale debt security that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive loss. Regardless of our intent to sell a security, we perform additional analysis on all securities in an unrealized loss position to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security and are recorded within earnings as an impairment loss. Liquidity As of December 31, 2020, our cash, cash equivalents and available-for-sale securities balance was $34.1 million. On February 17, 2021, we completed a public offering receiving net proceeds of approximately $86.0 million. See Note 16 for additional details of the public offering. We have primarily incurred operating losses since inception and have relied on our ability to fund our operations through collaboration and license arrangements, or other strategic arrangements, and through the sale of stock. We expect to continue to spend significant resources to fund the development and potential commercialization of eganelisib, also known as IPI-549, an orally administered immuno-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. We believe that our existing cash, cash equivalents and available-for-sale securities, together with the $86.0 million net proceeds from the public offering, will be adequate to satisfy our current operating plans for at least the next twelve months from the issuance of these financial statements. Concentration of Credit Risk Cash and cash equivalents are primarily maintained with two major financial institutions in the United States. Deposits at banks may exceed the insurance provided on such deposits. Generally, these deposits may be redeemed upon demand and, therefore, bear minimal risk. Financial instruments that potentially subject us to concentration of credit risk primarily consist of available-for-sale securities. Available-for-sale securities consist of U.S. Treasury securities and U.S. government-sponsored enterprise obligations. Our investment policy, which has been approved by our Board of Directors, limits the amount that we may invest in any one issuer of investments, thereby reducing credit risk concentrations. Property and Equipment Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account, and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements, building improvements and capital leases is recorded as depreciation expense and included in research and development and general and administrative expense, as applicable. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods: Computer equipment and software 3 to 5 years Leasehold improvements Shorter of lease term or useful life of asset Furniture and fixtures 7 to 10 years Impairment of Long-Lived Assets We evaluate our long-lived assets for potential impairment. Potential impairment is assessed when there is evidence that events or changes in circumstances have occurred that indicate that the carrying amount of a long-lived asset may not be recovered. Recoverability of these assets is assessed based on undiscounted expected future cash flows from the assets, considering a number of factors, including past operating results, budgets and economic projections, market trends and product development cycles. An impairment in the carrying value of each asset is assessed when the undiscounted expected future cash flows, including its eventual residual value, derived from the asset are less than its carrying value. Impairments, if any, are recognized in earnings. An impairment loss would be recognized in an amount equal to the excess of the carrying amount over the undiscounted expected future cash flows. Fair Value Measurements We define fair value as the price that we would receive to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. 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. We value our available-for-sale securities utilizing third-party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third-party pricing services by understanding the models used, obtaining market values from other pricing sources and confirming that those securities trade in active markets. Liabilities Related to Sale of Future Royalties We treat the liabilities related to sale of future royalties (see Note 9 and Note 10) as a debt financings, amortized under the effective interest rate method over the estimated life of the related expected royalty stream. The liabilities related to sale of future royalties and the debt amortization are based on our current estimates of future royalties expected to be paid over the life of the arrangement. We will periodically assess the expected royalty payments using projections from external sources. To the extent our estimates of future royalty payments are greater or less than previous estimates or the estimated timing of such payments is materially different than previous estimates, we will adjust the effective interest rate and recognize related non-cash interest expense on a prospective basis. Non-cash royalty revenue is reflected as royalty revenue, and non-cash amortization of debt is reflected as interest expense in the Consolidated Statement of Operations and Comprehensive Loss. Revenue Recognition To date, all our revenue has been generated under collaboration agreements, including payments to us of upfront license fees, funding or reimbursement of research and development efforts, milestone payments, if specified objectives are achieved, and royalties on product sales. We recognize revenue when we transfers goods or services to customers in an amount that reflects the consideration that we expect to receive for those goods or services. These principles 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. Each reporting period we re-evaluate the probability of achievement of such milestones and any related constraints. 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 recognize sales-based milestones and royalty revenue based upon net sales by the licensee of licensed products in licensed territories, and 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. In the event of an early termination of a collaboration agreement, any contract liabilities would be recognized in the period in which all our obligations under the agreement have been fulfilled. Research and Development Expense Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, comparator and combination drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense upfront license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. Prepaid comparator and combination drug expenses are capitalized and then recognized as expense when title transfers to us. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses incurred by us, we evaluate the terms of the arrangement to determine whether the reimbursement should be recorded as revenue or as an offset to research and development expense. If the arrangement provides for us to reimburse the collaborator for research and development expenses or for the achievement of a development milestone for which a payment is due, we record the reimbursement or the achievement of the development milestone as research and development expense. Stock-based Compensation Expense For awards granted to employees, directors, non-employees, and awards granted under our 2013 Employee Stock Purchase Plan, or ESPP, we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. Stock-based compensation costs for non-employees are recognized as expense over the vesting period on a ratable basis. We use the Black-Scholes valuation model in determining the fair value of all equity awards. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized. When the performance conditions related to these awards are determined to be probable, we recognize the expense over the requisite service period. We have no awards with market conditions. Royalty Expense Royalty expense is recorded when incurred and represents the expense associated with amounts owed to third parties as a result of royalty revenue recognized and the amounts owed by us to Takeda Pharmaceutical Company Limited, or Takeda, in relation to sale of future royalties (see Note 12). Income Taxes We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date. We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense. Due to the uncertainty surrounding the realization of the net deferred tax assets in future periods, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets as of December 31, 2020 and 2019. 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 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 loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive: At December 31, 2020 2019 Stock options 12,664,664 9,576,319 Warrants 1,000,000 1,000,000 Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive loss. Other comprehensive loss is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired. During the year ended December 31, 2020, there were no material reclassifications out of accumulated other comprehensive loss. New Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Statements , or ASU No. 2016-13, which requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates , whereby the effective date of this standard for smaller reporting companies was deferred to annual reporting periods beginning after December 15, 2022, including interim periods within those annual reporting periods, and early adoption is still permitted. We are currently evaluating the impact of ASU No. 2016-13 on our consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , or ASU No. 2020-06, which simplifies the guidance on an issuer’s accounting for convertible instruments and contracts in its own equity. The provisions of ASU No. 2020-06 are applicable for fiscal years beginning after December 15, 2023, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. We are currently evaluating the impact of ASU No. 2020-06 on our consolidated financial statements.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	3. Stock-Based Compensation Under each of the stock incentive plans described below, stock option awards made to new employees upon commencement of employment typically provide for vesting of 25% of the shares underlying the award at the end of the first year of service with the remaining 75% of the shares underlying the award vesting ratably on a monthly basis over the following three-year period subject to continued service. Annual grants to existing employees typically provide for ratable vesting over specified periods determined by the Board of Directors. In addition, under each plan, all options granted expire no later than ten years after the date of grant. 2019 Equity Incentive Plan Our 2019 Equity Incentive Plan, or the 2019 Plan, was approved by our stockholders in June 2019. The 2019 Plan provides for the grant of incentive stock options intended to qualify under Section 422 of the Internal Revenue Code of 1986, as amended, or IRC, as well as nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based and cash-based awards. Up to 6,031,009 shares of our common stock may be issued pursuant to awards granted under the 2019 Plan, plus an additional amount of our common stock underlying awards issued under the 2010 Stock Incentive Plan, or the 2010 Plan, that expire or are canceled without the holders receiving any shares under those awards. As of December 31, 2020, an aggregate of 5,130,033 shares of our common stock were reserved for issuance upon the exercise of outstanding awards, and up to 2,084,050 shares of common stock may be issued pursuant to awards granted under the 2019 Plan. 2010 Stock Incentive Plan The 2010 Plan provided for the grant of incentive stock options under the IRC, as well as nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based and cash-based awards. As of December 31, 2020, an aggregate of 7,534,631 shares of our common stock were reserved for issuance upon the exercise of outstanding awards granted under the 2010 Plan. The 2010 Plan was terminated upon approval of the 2019 Plan; therefore, no further grants may be made under the 2010 Plan. 2013 Employee Stock Purchase Plan Our ESPP permits eligible employees to purchase shares of our common stock at a discount and consists of consecutive, overlapping 24-month offering periods, each consisting of four six-month purchase periods. On the first day of each offering period, each employee who is enrolled in the ESPP will automatically receive an option to purchase up to a whole number of shares of our common stock. The purchase price of each of the shares purchased, in a given purchase period, will be 85% of the closing price of a share of our common stock, on the first day of the offering period or the last day of the purchase period, whichever is lower. During the year ended December 31, 2020, 91,696 shares of common stock were purchased for total proceeds of approximately $0.1 million. During the year ended December 31, 2019, 110,459 shares of common stock were purchased for total proceeds of approximately $0.1 million. Compensation Expense Total stock-based compensation expense, related to all equity awards, comprised the following: Year Ended December 31, 2020 2019 (in thousands) Research and development $ 383 $ 491 General and administrative 1,073 1,642 Total stock-based compensation expense $ 1,456 $ 2,133 As of December 31, 2020, we had approximately $5.4 million of total unrecognized compensation cost related to unvested common stock options and awards under our ESPP, which are expected to be recognized over a weighted-average period of 3.3 years. Stock Options Valuation Assumptions We estimate the fair value of stock options at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions: December 31, 2020 2019 Risk-free interest rate 1.0 % 2.3 % Expected annual dividend yield — — Expected stock price volatility 98.3 % 99.4 % Expected term of options 5.7 years 5.9 years The valuation assumptions were determined as follows: • Risk-free interest rate: The yield on zero-coupon U.S. Treasury securities for a period that was commensurate with the expected term of the awards. • Expected annual dividend yield: The estimate for annual dividends was zero because we have not historically paid a dividend and do not intend to do so in the foreseeable future. • Expected stock price volatility: We determined the expected volatility by using our available implied and historical price information. • Expected term of options: The expected term of the awards represents the period of time that the awards were expected to be outstanding. We use the simplified method to estimate expected term, whereby, the expected life equals the average of the vesting term and the original contractual term of the option. We recognize forfeitures related to employee share-based payments as they occur. A summary of our stock option activity for the year ended December 31, 2020 is as follows: Stock Options Weighted- Weighted-Average Aggregate Outstanding at January 1, 2020 9,576,319 $ 4.58 Granted 4,999,811 1.50 Exercised (46,433) 1.83 Forfeited (694,584) 1.26 Expired (1,170,449) 5.17 Outstanding at December 31, 2020 12,664,664 $ 3.51 7.0 $ 6.2 Exercisable at December 31, 2020 8,079,577 $ 4.62 5.6 $ 3.5 The weighted-average fair value per share of options granted during the years ended December 31, 2020 and 2019 was $1.15 and $1.07, respectively. The aggregate intrinsic value of options outstanding at December 31, 2020 was calculated based on the positive difference, if any, between the closing fair market value of our common stock on December 31, 2020 and the exercise price of the underlying options. No related income tax benefits were recorded during the years ended December 31, 2020 or 2019. We settle employee stock option exercises with newly issued shares of our common stock.

Cash, Cash Equivalents and Avai

Cash, Cash Equivalents and Available-for-Sale Securities	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Available-for-Sale Securities	4. Cash, Cash Equivalents and Available-for-Sale Securities The following is a summary of cash, cash equivalents and available-for-sale securities: December 31, 2020 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 28,593 $ — $ — $ 28,593 Available-for-sale securities: U.S. Treasury securities due in one year or less 5,516 — (1) 5,515 Total available-for-sale securities 5,516 — (1) 5,515 Total cash, cash equivalents and available-for-sale securities $ 34,109 $ — $ (1) $ 34,108 December 31, 2019 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 22,260 $ — $ — $ 22,260 Available-for-sale securities: U.S. Treasury securities due in one year or less 8,244 4 — 8,248 U.S. government-sponsored enterprise obligations due in one year or less 11,928 8 — 11,936 Total available-for-sale securities 20,172 12 — 20,184 Total cash, cash equivalents and available-for-sale securities $ 42,432 $ 12 $ — $ 42,444 We held three debt securities at December 31, 2020 that were in an unrealized loss position for less than twelve months. The fair value of these securities was $4.5 million. As of December 31, 2020, we did not hold any securities in foreign financial institutions. We evaluated our securities for other-than-temporary impairments based on quantitative and qualitative factors. We considered the decline in market value for these three securities to be primarily attributable to current economic and market conditions. It is not more likely than not that we will be required to sell these securities, and we do not intend to sell these securities before the recovery of their amortized cost bases. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of December 31, 2020. We had no material realized gains or losses on our available-for-sale securities for the years ended December 31, 2020 and 2019. There were no other-than-temporary impairments recognized for the years ended December 31, 2020 and 2019.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value	5. Fair Value The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2020 and 2019: December 31, 2020 Level 1 Level 2 Level 3 (in thousands) Assets: Cash and cash equivalents $ 28,593 $ — $ — U.S. Treasury securities — 5,515 — Total assets $ 28,593 $ 5,515 $ — Liabilities: Warrant liability $ — $ — $ 198 Total liabilities $ — $ — $ 198 December 31, 2019 Level 1 Level 2 Level 3 (in thousands) Assets: Cash and cash equivalents $ 20,860 $ 1,400 $ — U.S. Treasury securities — 8,248 — U.S. government-sponsored enterprise obligations — 11,936 — Total assets $ 20,860 $ 21,584 $ — The fair value of the available-for-sale securities and cash and cash equivalents is based on the following inputs for both U.S. Treasury securities and U.S, government-sponsored enterprise obligations: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including TRACE ® reported trades. There have been no changes to our valuation methods during the year ended December 31, 2020. We had no available-for-sale securities that were classified as Level 3 at any point during the year ended December 31, 2020. Warrant liability relates to potential future warrants that may be issued. The fair value of the warrant liability on the date of the commitment and on each re-measurement date for those warrants classified as liabilities was estimated using the Monte Carlo simulation model, which involves a series of simulated future stock price paths over the remaining life of the commitment. The fair value is estimated by taking the average of the fair values under each of many Monte Carlo simulations. The fair value estimate is affected by our stock price, as well as estimated future financing needs, including timing and sources of the financing and subjective variables including expected stock price volatility over the remaining life of the commitment and risk-free interest rate. Due to the nature of these inputs, the valuation of the warrants is considered a Level 3 measurement. The fair value of the warrant liability as of December 31, 2020 has been included in other liabilities on our consolidated balance sheet. See Note 10 for further discussions of the accounting for the warrants. The carrying amounts reflected in the 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.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Expenses and Other Current Assets	6. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: December 31, 2020 2019 (in thousands) Prepaid expenses $ 1,528 $ 1,680 Other current assets 234 457 Restricted cash, current portion 150 — Total prepaid expenses and other current assets $ 1,912 $ 2,137

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property and Equipment	7. Property and Equipment Property and equipment consist of the following: December 31, 2020 2019 (in thousands) Computer equipment and software $ 1,893 $ 1,893 Furniture and fixtures 446 446 Leasehold improvements 1,743 1,735 4,082 4,074 Less accumulated depreciation (2,372) (1,888) $ 1,710 $ 2,186

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued Expenses	8. Accrued Expenses Accrued expenses consisted of the following: December 31, 2020 2019 (in thousands) Accrued compensation and benefits $ 2,385 $ 3,055 Accrued clinical and development 3,511 3,793 Liability related to sale of future royalties, net, current portion 848 — Operating lease liability, current portion 489 381 Other 832 848 Total accrued expenses $ 8,065 $ 8,077

Liability Related to Sale of Fu

Liability Related to Sale of Future Royalties	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Liability Related to Sale of Future Royalties	9. Liability Related to Sale of Future Royalties In 2016, we and Verastem Inc., or Verastem, entered into an amended and restated license agreement, or the Verastem Agreement, under which we granted to Verastem an exclusive worldwide license in oncology indications for the research, development, commercialization, and manufacture of duvelisib and products containing duvelisib, or Copiktra ® , an oral, dual inhibitor of PI3K delta and gamma, which we refer to as Licensed Products, in each case in oncology indications. In September 2020, Verastem completed a disposition of its rights, title, and interest in and to duvelisib to Secura Bio, Inc., or Secura Bio, wherein Secura Bio assumed all liabilities and obligations under the Verastem Agreement. We now refer to the Verastem Agreement as the Secura Bio Agreement. Verastem was obligated to pay us royalties on worldwide net sales of Licensed Products ranging from the mid-single digits to the high-single digits, a portion of which we are obligated to share with Takeda as described in Note 12. Secura Bio assumed these obligations as of October 1, 2020. On March 5, 2019, we and HealthCare Royalty Partners III, L.P., or HCR, entered into a purchase and sale agreement, or the HCR Agreement, providing for the acquisition by HCR of our interest in certain royalty payments, or the Purchased Assets, based on worldwide annual net sales of Licensed Products, pursuant to the Secura Bio Agreement. On March 11, 2019, which we refer to as the HCR Closing Date, we received $30.0 million, or the HCR Closing Date Payment, less certain transaction expenses. After sharing with Takeda in accordance with the Takeda Amendment, as defined in Note 12, we retained $22.5 million in gross proceeds, or approximately $20.9 million in net proceeds. Pursuant to the HCR Agreement, our sale of the Purchased Assets is subject to an increasing cap amount defined below, which we refer to as the Cap Amount. The Cap Amount is equal to, for each applicable time period specified below, a multiple, as set forth below, of (a) the HCR Closing Date Payment plus (b) 100% of the reasonably incurred Applicable Purchaser Expenditures, as defined below: Time Period Cap Amount From the HCR Closing Date until June 30, 2022 145 % From July 1, 2022 through June 30, 2023 155 % From July 1, 2023 through June 30, 2024 165 % From July 1, 2024 through June 30, 2025 175 % On any date that aggregate royalty payments made to HCR equal the Cap Amount applicable to such date, or the Cap Date, the HCR Agreement will automatically terminate, and all rights to the royalty stream with respect to the Licensed Product will revert back to us, which we refer to as the Reversion. If the Cap Date has not been achieved by June 30, 2025, there shall be no Cap Date, and the term of the HCR Agreement shall continue through the term of the Secura Bio Agreement. Prior to June 30, 2025, we shall have the right, but not the obligation, at any time prior to the Cap Date, if applicable, to cause the occurrence of the Cap Date (including for the purpose of determining the termination date of the HCR Agreement) by paying to HCR an amount equal to (i) the then-applicable Cap Amount less (ii) 100% of all payments made in respect of the Purchased Assets received by HCR through the date of such payment. In addition to the Cap Date, the HCR Agreement (a) may be terminated by mutual agreement of us and HCR, and (b) shall automatically terminate upon the expiration of our and Secura Bio’s obligations to each other under the Secura Bio Agreement (for a reason other than early termination thereof). We recognized the proceeds received from HCR as a liability that is being amortized using the effective interest method over the life of the arrangement. As the basis for our determination, we considered, in accordance with the relevant accounting guidance, our right to the Reversion, if any, and our right to terminate the HCR Agreement by making payment to achieve the Cap Date. We are not obligated to repay the proceeds received under the HCR Agreement. We recorded the receipt of the $30.0 million payment from HCR as a liability, net of debt discount and issuance costs of approximately $2.4 million. In order to determine the amortization of the liability, we are required to estimate the total amount of future net royalty payments to be made to HCR over the term of the HCR Agreement. The total threshold of net royalties to be paid, less the net proceeds received, will be recorded as interest expense over the life of the liability. We impute interest on the unamortized portion of the liability using the effective interest method. Interest and debt discount amortization expense is reflected as interest expense in the Consolidated Statement of Operations and Comprehensive Loss. Over the course of the HCR Agreement, the actual interest rate will be affected by the amount and timing of royalty revenue recognized and changes in forecasted royalty revenue. On a quarterly basis, we reassess the effective interest rate and adjust the rate prospectively as needed. The following table shows the activity within the liability account for the year ended December 31, 2020 and 2019: December 31, 2020 2019 (in thousands) Liability related to sale of future royalties - beginning balance $ 29,626 $ — Proceeds from sale of future royalties — 30,000 Debt discount and issuance costs — (2,382) Non-cash royalty revenue (910) (555) Non-cash interest expense recognized 153 2,563 Liability related to sale of future royalties, net - ending balance $ 28,869 $ 29,626 Less: current portion (848) — Liability related to sale of future royalties, net, less current portion $ 28,021 $ 29,626

Liability Related to Sale of _2

Liability Related to Sale of Future Royalties - Related Party Transaction	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Liability Related to Sale of Future Royalties - Related Party Transaction	10. Liability Related to Sale of Future Royalties — Related Party Transaction Funding Agreement On January 8, 2020, or the BVF Closing Date, we entered into a funding agreement, or the BVF Funding Agreement, with BVF and Royalty Security, LLC, a wholly owned subsidiary of BVF, or the Buyer. The BVF Funding Agreement provides for the acquisition by the Buyer of our interest in all royalty payments based on worldwide annual net sales of patidegib, or the BVF Licensed Product, excluding Trailing Mundipharma Royalties, as defined in Note 12, related to patidegib. We refer to all BVF Licensed Product royalties owed to us less Trailing Mundipharma Royalties as the Royalty or Royalties. Such Royalties are owed to us pursuant to the PellePharm Agreement, as defined in Note 12, by and between us and PellePharm Inc., or PellePharm. The Buyer and BVF are affiliates of Biotechnology Value Fund, L.P., which beneficially owned approximately 30% of our common stock at the time of the transaction. Effective February 17, 2021, Biotechnology Value Fund, L.P. is not considered a related party. Pursuant to the BVF Funding Agreement, we received $20.0 million, or the Upfront Purchase Price, less certain transaction expenses. We transferred to the Buyer (i) the Royalty, (ii) the PellePharm Agreement (subject to our rights to milestone payments and rights to equity in PellePharm under the PellePharm Agreement), and (iii) certain patent rights established in the BVF Funding Agreement, with (i), (ii), and (iii) together referred to as Transferred Assets. We preserved our rights under the PellePharm Agreement to receive potential regulatory, commercial, and success-based milestone payments. In addition to the Upfront Purchase Price, we will also be entitled to receive a $5.0 million milestone payment, or Milestone Payment, from the Buyer if a milestone associated with PellePharm’s ongoing Phase 3 clinical trial of patidegib topical gel is achieved. On January 27, 2020, we entered into a novation and amendment agreement, or the Novation and Amendment Agreement, with BVF, the Buyer, and Royalty Security Holdings, LLC, an entity wholly owned by the BVF-related entities that funded the initial advance under the Funding Agreement, or Holdco. The Novation and Amendment Agreement amended the Funding Agreement by substituting Holdco in the place of BVF under the Funding Agreement, with Holdco assuming all rights and obligations of BVF under, arising out of or in connection with the Funding Agreement and agreeing to be bound in all respects in place of BVF under the Funding Agreement. Pursuant to the Novation and Amendment Agreement, BVF, as the manager of Holdco, agreed to guarantee the payment and performance by Holdco of its obligations under the Funding Agreement. Option to Repurchase Royalty Rights Upon or after anytime at which our common stock achieves a 20-day volume-weighted average price on the Nasdaq Stock Market, LLC, or Nasdaq, equal to or greater than $5.00 per share (adjusted for any stock splits, reverse splits, or similar arrangements), or the Purchase Threshold, we have an option to purchase from Holdco 100% of the outstanding equity interests of the Buyer, or the Option. To exercise the Option, we must deliver to Holdco (a) notice (or the Option Notice, with the date on which delivery of the Option Notice is given, the Option Notice Date) of our election to do so prior to the earliest to occur of: (i) the occurrence of certain trigger events identified in the BVF Funding Agreement, including a material failure by us to perform certain covenants, a failure by us to cause the BVF Funding Agreement and related agreements to remain in full force and effect, a deficiency in any security interest purported to be created by the BVF Funding Agreement resulting from an act or omission by us, or another insolvency event of us (upon the expiration of any applicable cure period) (each, a Trigger Event), (ii) the third anniversary of the BVF Closing Date, or (iii) the date immediately prior to a change of control of us (together, the Option Expiration Date), and (b) within ten (10) business days after the Option Notice is deemed delivered to Holdco (the Repurchase Date), an amount equal to the Upfront Purchase Price plus the Milestone Payment, if and when paid to us, plus the Option Premium, defined below, less the aggregate amount of all Royalty payments received by Buyer as of the Option Exercise Date. The exercise of the Option may only occur if our common stock maintains a 20-day volume-weighted average price on Nasdaq of $5.00 per share (adjusted for any stock splits, reverse splits, or similar arrangements) on each trading day between the Option Notice Date and the Repurchase Date. Option Premium means an amount accruing daily on (x) the Upfront Purchase Price plus the Milestone Payment, if and when paid to us, as of such date of payment, less (y) the aggregate amount of all Royalty payments received by Buyer as of such day, at a rate of 10% per annum, compounded quarterly. For purposes of calculating the Option Premium, in the event of a Trigger Event, the rate of accrual following the occurrence of such Trigger Event shall be increased to 20% per annum. Liability to Related Party We recognized the proceeds received under the BVF Funding Agreement as a liability that will be amortized using the effective interest method over the life of the arrangement. We recorded the receipt of the $20.0 million Upfront Purchase Price as a liability, net of debt issuance costs of approximately $0.4 million and warrant liability of $0.3 million. We are not obligated to repay the proceeds received under the BVF Funding Agreement. In order to determine the amortization of the liability, we are required to estimate the total amount of potential future net royalty payments to be made by PellePharm to the Buyer over the term of the BVF Funding Agreement. The total estimated net royalties to be paid, less the net proceeds received, will be recorded as interest expense over the life of the liability. We estimated an effective annual interest rate of approximately 11% as of the BVF Closing Date. Interest and debt discount amortization expense is reflected as related party interest expense in our consolidated statements of operations. We recognized $2.3 million of non-cash related party interest expense during the year ended December 31, 2020. Over the course of the BVF Funding Agreement, the actual interest rate will be affected by the amount and timing of royalty revenue recognized, if any, and changes in forecasted royalty revenue. There are a number of factors that could materially affect the amount and timing of royalty payments from PellePharm, none of which are within our control. On a quarterly basis, we will reassess the effective interest rate and adjust the rate prospectively as needed. The following table shows the activity within the liability account from the inception of the BVF Funding Agreement through December 31, 2020: December 31, 2020 (in thousands) Liability related to sale of future royalties to a related party - beginning balance $ — Proceeds from sale of future royalties 20,000 Debt discount and issuance costs (428) Warrant liability (305) Non-cash related party interest expense recognized 2,292 Liability related to sale of future royalties to a related party - ending balance $ 21,559 Potential Future Warrants The BVF Funding Agreement provides that, for so long as we have not exercised the Option, (a) if, during the 36-month period following the BVF Closing Date, we issue and sell in the aggregate more than 8,554,345 shares of our common stock (including options, warrants, convertible stock, convertible debt and other common-stock equivalents), known as the Warrant Threshold, and (b) any shares are issued in excess of the Warrant Threshold with consideration to us of less than $3.75 per share (as adjusted for any stock splits, reverse stock splits or other similar recapitalization events), or the Threshold Price, then we are obligated to issue to BVF warrants to purchase a number of shares of our common stock equal to 50% of the number of shares of our common stock issued and sold by us in excess of the Warrant Threshold below the Threshold Price, with any such Warrants having an exercise price equal to 1.5 times the price per share of such shares issued in excess of the Warrant Threshold. Pursuant to the Novation and Amendment Agreement, the form of such warrant was amended and restated to clarify that BVF may not exercise such warrant if the exercise price would be at a discount in accordance with applicable Nasdaq Stock Market rules, absent approval of our stockholders. To the extent that BVF seeks to exercise such a discounted warrant more than six months after the initial issuance and we are unable to deliver any portion of the underlying shares due to the limitations imposed by Nasdaq, then we must pay BVF an amount equal to the number of shares that cannot be delivered, calculated on a cashless exercise basis, multiplied by the fair market value of a share of our common stock, in each case, calculated in accordance with the terms of the warrant. Certain issuances of our common stock are excluded from the calculation of the Warrant Threshold, including the grant, exercise, or vesting of options or awards granted pursuant to our stock incentive plans or stock purchase plans. Once the Warrant Threshold has been met, the requirement to issue warrants does not apply to certain issuances of our common stock, including the grant, exercise, or vesting of options or awards granted pursuant to our stock incentive plans or stock purchase plans and, subject to certain limitations, the issuance of shares of common stock in connection with a transaction with an unaffiliated third party that includes a debt financing or a bona fide commercial relationship or any acquisition of assets, merger with, or acquisition of another entity. We determined that the commitment to issue warrants represents a freestanding financial instrument and accounted for it as a liability as of the BVF Closing Date. The fair value of the warrant liability was estimated using the Monte Carlo simulation model. The fair value of the warrant liability as of December 31, 2020 has been included in other liabilities on our consolidated balance sheet. We will re-measure the warrant liability at each reporting date. Changes in fair value of the warrant liability is included in investment and other income on our consolidated statement of operations and comprehensive loss. No warrants were issued as of December 31, 2020. See Note 5 for further discussions of the fair value of the warrants. In addition to exercise of the Option, the BVF Funding Agreement may be terminated by mutual written agreement of us and the Buyer.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies We previously subleased 6,091 square feet of office space at 784 Memorial Drive, Cambridge, Massachusetts. The term of the lease commenced on September 1, 2017 and expired on August 31, 2019. From September 1, 2017 through August 31, 2018, the base rent of the lease was $19,796 per month. From September 1, 2018 until the expiration date, the base rent of the lease was $20,303 per month. In addition to the base rent, we were also responsible for our share of the operating expenses, utility costs and real estate taxes, in accordance with the terms of the lease. On April 5, 2019, we entered into a lease agreement, or the Lease, with Sun Life Assurance Company of Canada, or the Landlord, effective April 3, 2019, or the Commencement Date, for the lease of approximately 10,097 square feet of office space at 1100 Massachusetts Avenue, Cambridge, Massachusetts, or the Leased Premises. The term of the Lease commenced on the Commencement Date and expires on August 1, 2024, or the Expiration Date, approximately five years after the Rent Commencement Date as described below. Beginning August 1, 2019, or the Rent Commencement Date, the total base rent of the Lease is $47,961 per month and will increase by approximately 3% on each anniversary of the Rent Commencement Date until the Expiration Date. In addition to the base rent, we are also responsible for our share of the operating expenses, insurance, real estate taxes and certain capital costs, and we are responsible for utilities in our premises, all in accordance with the terms of the Lease. Pursuant to the terms of the Lease, we provided a security deposit in the form of a letter of credit in the initial amount of $300,000, which may be reduced to $150,000 over time in accordance with the terms of the Lease. The security deposit plus the associated bank fee of $15,000 is included on our consolidated balance sheet as prepaid expenses and other current assets and restricted cash, less current portion as of December 31, 2020. The Landlord provided a lease incentive allowance of $0.6 million to fund certain improvements to be made by us to the Leased Premises. Subject to certain conditions specified in the Lease, we have the right to extend the term of the Lease for two years, if we provide notice to the Landlord not earlier than twelve months, nor later than nine months, prior to expiration of the Lease. The base rent for the extension term shall be equal to the greater of the base rent in effect for the last year of the initial lease term or a fair market base rent determined according to the terms of the Lease. The Lease contains customary provisions allowing the Landlord to, among other things, accelerate payments under the Lease or terminate the Lease in its entirety if we fail to remedy a default of any of our obligations under the Lease within specified time periods or upon our bankruptcy or insolvency. Following the adoption of ASC 842, we recorded an asset and liability for the remaining term of our sublease, our data center lease and the Lease. We combine lease and nonlease components for our leases. Our leases do not provide an implicit rate; therefore, we use an estimate of our incremental borrowing rate based on the information available at the adoption date or lease commencement date in determining the present value of lease payments. The following is a summary of our current leases included in the respective balance sheet classifications: December 31, 2020 2019 Assets (in thousands) Operating lease right-of-use assets $ 1,419 $ 1,717 Liabilities Accrued expenses and other current liabilities $ 489 $ 381 Operating lease liability 1,436 1,926 Total lease liabilities $ 1,925 $ 2,307 As of December 31, 2020, the weighted average term remaining on our leases is 3.5 years, and the weighted average discount rate is 10%. As of December 31, 2019, the weighted average term remaining on our leases was 4.5 years, and the weighted average discount rate was 10%. Operating lease costs, including variable costs, of $0.7 million and $0.8 million were incurred during the years ended December 31, 2020 and 2019, respectively. Cash paid for amounts included in the measurement of lease liabilities was $0.7 million and $0.4 million during the year ended December 31, 2020 and 2019, respectively. As of December 31, 2020, future minimum lease payments of our operating lease liabilities are as follows: Operating Leases (in thousands) 2021 660 2022 640 2023 658 2024 334 Total future minimum lease payments 2,292 Less: imputed interest (367) Total lease liability $ 1,925

Strategic Agreements

Strategic Agreements	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Strategic Agreements	12. Strategic Agreements We have worldwide development and commercialization rights to eganelisib, subject to certain obligations to our licensor, Takeda Pharmaceutical Company Limited, or Takeda, as described in more detail below. Additionally, we are obligated to pay Mundipharma International Corporation Limited, or Mundipharma, and Purdue Pharmaceutical Products L.P., or Purdue, a 4% royalty in the aggregate on worldwide net sales of products that were previously subject to our strategic alliance with Mundipharma and Purdue that was terminated in 2012. Such products include eganelisib; duvelisib, the PI3K delta,gamma inhibitor we licensed to Verastem in 2016, and Verastem sold its interest in these rights to Secura Bio in 2020; and IPI-926, or patidegib, part of the hedgehog inhibitor program we licensed to PellePharm in 2013. We refer to such royalties as Trailing Mundipharma Royalties. After Mundipharma and Purdue have recovered approximately $260.0 million in royalty payments from all products that were previously subject to the strategic alliance, which represents the funding paid to us for research and development services performed by us under this strategic alliance, the Trailing Mundipharma Royalties will be reduced to a 1% royalty on net sales in the United States of such products. As of December 31, 2020, Mundipharma and Purdue have recovered $1.4 million. PellePharm In June 2013, we entered into a license agreement with PellePharm, under which we granted PellePharm exclusive global development and commercialization rights to our hedgehog inhibitor program, including patidegib, 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 $9.0 million in remaining 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. During the year ended December 31, 2019, we recognized $2.0 million in revenue related to a milestone payment for PellePharm’s initiation of a Phase 3 study investigating patidegib in patients with Gorlin Syndrome, a rare genetic disease that leads to the chronic formation of multiple basal cell carcinomas, as this milestone payment is variable consideration that became unconstrained following initiation of the study. The remaining milestones have not been recognized 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. PellePharm is also obligated to pay us tiered royalties on annual net sales of Hedgehog Products, which are subject to reduction after a certain aggregate funding threshold has been achieved. On January 8, 2020, we entered into the BVF Funding Agreement, pursuant to which we sold our interest, subject to a repurchase option, or the Option, in all royalty payments based on worldwide annual net sales of the BVF Licensed Product, excluding Trailing Mundipharma Royalties related to patidegib. The terms of the BVF Funding Agreement, including the Option, is further described in Note 10. 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 eganelisib and duvelisib. In January 2012, Intellikine was acquired by Takeda. In December 2012, we amended and restated our development and license agreement with Takeda and further amended the agreement in July 2014, September 2016, July 2017, and March 2019. We refer to the amended and restated development and license agreement, as amended, as the Takeda Agreement. Duvelisib Pursuant to the Takeda Agreement, prior to March 4, 2019, we were obligated to share equally with Takeda all revenue arising from certain qualifying transactions for duvelisib, including the Secura Bio Agreement, subject to certain exceptions including revenue we receive as reimbursement for duvelisib research and development expenses. By entry into a fourth amendment to the Takeda Agreement on March 4, 2019, or the Takeda Amendment, Takeda consented to the sale of the Purchased Assets to HCR and agreed to forego its rights to an equal share of the royalties due from Secura Bio during the period prior to the Reversion and agreed not to seek any payment from HCR with respect to the royalties owed to Takeda. In exchange, we paid Takeda $6.7 million representing 25% of the HCR Closing Date Payment, net of 25% of the expenses incurred by us in connection with the HCR Agreement. In addition, we agreed to pay Takeda 25% of the royalties that would have been payable to us by Secura Bio but for the consummation of the HCR Agreement, which we refer to as the Interim Obligation. During the year ended December 31, 2020, we recognized $0.2 million in Interim Obligation amounts owed to Takeda as royalty expense. During the year ended December 31, 2019, we recognized the $6.7 million payment and $0.1 million in Interim Obligation amounts owed to Takeda as royalty expense. We have the right to extinguish the Interim Obligation by payment to Takeda of an amount equal to (i) the $6.7 million payment multiplied by the multiple set forth in the table below corresponding to the time period in which such extinguishing payment is made, minus (ii) any payments made to Takeda pursuant to the Interim Obligation: Time Period Multiple From the Takeda Amendment Effective Date until June 30, 2022 145 % From July 1, 2022 through June 30, 2023 155 % From July 1, 2023 through June 30, 2024 165 % From July 1, 2024 through June 30, 2025 175 % The Interim Obligation shall expire upon the occurrence of the Reversion, at which time our obligations to share equally with Takeda the royalties payable under the Secura Bio Agreement shall be reinstated. Eganelisib Pursuant to the Takeda Agreement, in October 2019 we achieved and paid Takeda a $2.0 million milestone payment associated with our MARIO-275 study, our global, randomized, placebo-controlled Phase 2 study evaluating the effect of adding eganelisib to nivolumab, also known as Opdivo ® , in checkpoint-naïve advanced urothelial cancer patients whose cancer has progressed or recurred following treatment with platinum-based chemotherapy. We are further obligated to pay Takeda the remaining $3.0 million success-based development milestone and up to $165.0 million in remaining success-based regulatory and commercial milestones for one product candidate other than duvelisib that inhibits the PI3K pathway, which could be eganelisib.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes We did not have any income tax expense for the year ended December 31, 2020. We recognized an income tax benefit of $0.1 million for the year ended December 31, 2019 as a result of reversing the sequestration adjustment related to the monetizing of our alternative minimum tax credit carryforwards as permitted by the Tax Cut and Jobs Act, or the Act, that was enacted on December 22, 2017. Our income tax expense for the years ended December 31, 2020 and 2019 differed from the expected U.S. federal statutory income tax expense as set forth below: Years Ended December 31, 2020 2019 (in thousands) Expected federal tax benefit $ (8,503) $ (9,893) Permanent differences 211 352 State taxes, net of the deferred federal benefit (2,563) (2,905) Tax credit carryforwards (837) (738) Adjustments to deferred tax assets and deferred tax liabilities 852 265 Other 69 8 Change in valuation allowance 10,771 12,857 Income tax expense (benefit) $ — $ (54) The significant components of our deferred tax assets and liabilities are as follows: Years Ended December 31, 2020 2019 (in thousands) Deferred tax assets (liabilities): Net operating loss carryforwards $ 151,752 $ 145,024 Tax credit carryforwards 42,645 41,730 Intangible assets 17,028 18,977 Accrued expenses 645 590 Stock-based compensation 4,976 5,661 Sale of future royalties 13,742 8,088 Other (44) (98) Valuation allowance (230,744) (219,972) Net deferred tax assets $ — $ — We have recorded a valuation allowance against our deferred tax assets in each of the years ended December 31, 2020, and 2019 because we believe that it is more likely than not that these assets will not be realized. The valuation allowance increased by approximately $10.8 million during the year ended December 31, 2020 primarily as a result of the increase in our unbenefited net operating loss for the current period and the BVF Funding Agreement which has created a deferred tax asset in the year due to the current inclusion of the royalty sale proceeds in taxable income for 2020. The valuation allowance increased by approximately $12.9 million during the year ended December 31, 2019 primarily as a result of the increase in our unbenefited net operating loss for the current period and the HCR Agreement which has created a deferred tax asset in the year due to the current inclusion of the royalty sale proceeds in taxable income for 2019. Subject to the limitations described below, at December 31, 2020, we have cumulative net operating loss carryforwards of approximately $582.9 million and $464.2 million available to reduce federal and state taxable income, respectively. For federal purposes, the net operating loss carryforwards have begun to expire and will continue to expire through 2037 for losses incurred before January 1, 2018. Federal losses generated after December 31, 2017 do not expire. As of December 31, 2020, we have approximately $58.2 million of federal losses that do not expire. The state net operating loss carryforwards begin to expire in 2031 and continue to expire through 2040. In addition, we have cumulative federal and state tax credit carryforwards of $34.8 million and $9.9 million, respectively, available to reduce federal and state income taxes which expire through 2040 and 2034, respectively. Our net operating loss carryforwards and tax credit carryforwards are limited as a result of certain ownership changes, as defined under Sections 382 and 383 of the Internal Revenue Code. This limits the annual amount of these tax attributes that can be utilized to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on our value immediately prior to an ownership change. Subsequent ownership changes may affect the limitation in future years. The net operating losses and tax credit carryforwards that have and will expire unused in the future as a result of Section 382 and 383 limitations have been excluded from the amounts disclosed above. The latest Section 382 study was performed through December 31, 2018. Ownership changes after that date could further reduce the Company’s ability to utilize the net operating loss and other attribute carryforwards. At December 31, 2020 and 2019, we had no unrecognized tax benefits. As of December 31, 2020 and 2019, we had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in our consolidated statements of operations. We will recognize interest and penalties related to uncertain tax positions in income tax expense. For all years through December 31, 2020, we generated research credits but have not conducted a study to document the qualified activities. This study may result in an adjustment to our research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against our research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance. We file U.S. federal and California and Massachusetts state income tax returns. The statute of limitations for assessment by the Internal Revenue Service, or IRS, and state tax authorities is closed for tax years prior to 2017, although carryforward attributes that were generated prior to tax year 2017 may still be adjusted upon examination by the IRS or state tax authorities if they either have been or will be used in a future period.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	14. Stockholders’ Equity Common Stock Sales Facility On June 28, 2019, we entered into a Capital on Demand Sales Agreement with JonesTrading Institutional Services LLC, or JonesTrading, and on July 29, 2019 we amended and restated the sales agreement to add B. Riley FBR, Inc., or B. Riley FBR, as a party to the agreement. We refer to the amended and restated sales agreement as the ATM Sales Agreement. Pursuant to the ATM Sales Agreement we may offer and sell shares of our common stock having an aggregate offering price of up to $20.0 million from time to time through JonesTrading or B. Riley FBR, each acting as our sales agent. We have agreed to pay commissions to the sales agents for their services in acting as agents in the sale of our common stock in the amount of up to 3.0% of the gross proceeds from sales of our common stock pursuant to the ATM Sales Agreement. Sales of shares of our common stock under the ATM Sales Agreement may be made in sales deemed to be “at the market offerings” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended. With our prior written approval, JonesTrading or B. Riley FBR may also sell the shares by any other method permitted by law, including in negotiated transactions. We, JonesTrading, or B. Riley FBR may suspend or terminate the offering of shares upon notice to the other party and subject to other conditions. During the year ended December 31, 2020, we issued and sold 6,725,691 shares of common stock at a weighted average price per share of $1.17 at-the-market pursuant to the ATM Sales Agreement for $7.7 million in net proceeds. During the year ended December 31, 2019, we did not sell any shares under the ATM Sales Agreement. Common Stock In June 2020, we amended our Restated Certificate of Incorporation to increase the number of authorized shares of our common stock from 100,000,000 shares to 200,000,000 shares. The amendment was approved by our shareholders at the annual meeting of stockholders on June 17, 2020. Warrants

Defined Contribution Benefit Pl

Defined Contribution Benefit Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Defined Contribution Benefit Plan	15. Defined Contribution Benefit Plan We sponsor a 401(k) retirement plan in which substantially all of our full-time employees are eligible to participate. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. During the years ended December 31, 2020 and 2019, we matched participants’ contributions up to 6% of the participant’s pre-tax salary. Our matching contributions for the years ended December 31, 2020 and 2019 was $0.2 million in both years.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These 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 preparation of consolidated financial statements in accordance with generally accepted accounting principles requires our management to make estimates and judgments that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and judgments. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions.
Segment Information	Segment Information We operate in one business segment, which focuses on drug development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making.
Cash Equivalents and Available-For-Sale Securities	Cash Equivalents and Available-For-Sale Securities Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. Treasury securities, and U.S. government-sponsored enterprise obligations. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds, U.S. Treasury securities, and U.S. government-sponsored enterprise obligations., are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods. We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at December 31, 2020 and 2019 as “available-for-sale.” We carry available-for-sale securities at fair value. Unrealized gains and losses on available-for-sale debt securities are reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity. We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in investment and other income. The cost of securities sold is based on the specific identification method. We include in investment income interest and dividends on securities classified as available-for-sale. We conduct periodic reviews to identify and evaluate each available-for-sale debt security that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive loss.
Liquidity	Liquidity As of December 31, 2020, our cash, cash equivalents and available-for-sale securities balance was $34.1 million. On February 17, 2021, we completed a public offering receiving net proceeds of approximately $86.0 million. See Note 16 for additional details of the public offering. We have primarily incurred operating losses since inception and have relied on our ability to fund our operations through collaboration and license arrangements, or other strategic arrangements, and through the sale of stock. We expect to continue to spend significant resources to fund the development and potential commercialization of eganelisib, also known as IPI-549, an orally administered immuno-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. We believe that our existing cash, cash equivalents and available-for-sale securities, together with the $86.0 million net proceeds from the public offering, will be adequate to satisfy our current operating plans for at least the next twelve months from the issuance of these financial statements.
Concentration of Credit Risk	Concentration of Credit Risk Cash and cash equivalents are primarily maintained with two major financial institutions in the United States. Deposits at banks may exceed the insurance provided on such deposits. Generally, these deposits may be redeemed upon demand and, therefore, bear minimal risk. Financial instruments that potentially subject us to concentration of credit risk primarily consist of available-for-sale securities. Available-for-sale securities consist of U.S. Treasury securities and U.S. government-sponsored enterprise obligations. Our investment policy, which has been approved by our Board of Directors, limits the amount that we may invest in any one issuer of investments, thereby reducing credit risk concentrations.
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account, and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements, building improvements and capital leases is recorded as depreciation expense and included in research and development and general and administrative expense, as applicable. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods: Computer equipment and software 3 to 5 years Leasehold improvements Shorter of lease term or useful life of asset Furniture and fixtures 7 to 10 years
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We evaluate our long-lived assets for potential impairment. Potential impairment is assessed when there is evidence that events or changes in circumstances have occurred that indicate that the carrying amount of a long-lived asset may not be recovered. Recoverability of these assets is assessed based on undiscounted expected future cash flows from the assets, considering a number of factors, including past operating results, budgets and economic projections, market trends and product development cycles. An impairment in the carrying value of each asset is assessed when the undiscounted expected future cash flows, including its eventual residual value, derived from the asset are less than its carrying value. Impairments, if any, are recognized in earnings. An impairment loss would be recognized in an amount equal to the excess of the carrying amount over the undiscounted expected future cash flows.
Fair Value Measurements	Fair Value Measurements We define fair value as the price that we would receive to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. 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. We value our available-for-sale securities utilizing third-party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third-party pricing services by understanding the models used, obtaining market values from other pricing sources and confirming that those securities trade in active markets.
Liabilities Related to Sale of Future Royalties	Liabilities Related to Sale of Future Royalties We treat the liabilities related to sale of future royalties (see Note 9 and Note 10) as a debt financings, amortized under the effective interest rate method over the estimated life of the related expected royalty stream. The liabilities related to sale of future royalties and the debt amortization are based on our current estimates of future royalties expected to be paid over the life of the arrangement. We will periodically assess the expected royalty payments using projections from external sources. To the extent our estimates of future royalty payments are greater or less than previous estimates or the estimated timing of such payments is materially different than previous estimates, we will adjust the effective interest rate and recognize related non-cash interest expense on a prospective basis. Non-cash royalty revenue is reflected as royalty revenue, and non-cash amortization of debt is reflected as interest expense in the Consolidated Statement of Operations and Comprehensive Loss.
Revenue Recognition	Revenue Recognition To date, all our revenue has been generated under collaboration agreements, including payments to us of upfront license fees, funding or reimbursement of research and development efforts, milestone payments, if specified objectives are achieved, and royalties on product sales. We recognize revenue when we transfers goods or services to customers in an amount that reflects the consideration that we expect to receive for those goods or services. These principles 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. Each reporting period we re-evaluate the probability of achievement of such milestones and any related constraints. 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 recognize sales-based milestones and royalty revenue based upon net sales by the licensee of licensed products in licensed territories, and 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. In the event of an early termination of a collaboration agreement, any contract liabilities would be recognized in the period in which all our obligations under the agreement have been fulfilled.
Research and Development Expense	Research and Development Expense Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, comparator and combination drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense upfront license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. Prepaid comparator and combination drug expenses are capitalized and then recognized as expense when title transfers to us. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses incurred by us, we evaluate the terms of the arrangement to determine whether the reimbursement should be recorded as revenue or as an offset to research and development expense. If the arrangement provides for us to reimburse the collaborator for research and development expenses or for the achievement of a development milestone for which a payment is due, we record the reimbursement or the achievement of the development milestone as research and development expense.
Stock-based Compensation Expense	Stock-based Compensation ExpenseFor awards granted to employees, directors, non-employees, and awards granted under our 2013 Employee Stock Purchase Plan, or ESPP, we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. Stock-based compensation costs for non-employees are recognized as expense over the vesting period on a ratable basis. We use the Black-Scholes valuation model in determining the fair value of all equity awards. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized. When the performance conditions related to these awards are determined to be probable, we recognize the expense over the requisite service period.
Royalty Expense	Royalty Expense Royalty expense is recorded when incurred and represents the expense associated with amounts owed to third parties as a result of royalty revenue recognized and the amounts owed by us to Takeda Pharmaceutical Company Limited, or Takeda, in relation to sale of future royalties (see Note 12).
Income Taxes	Income Taxes We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date. We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense.
Basic and Diluted Net Loss per Common Share	Basic and Diluted Net Loss per Common ShareBasic 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 such method is more dilutive than the treasury stock method.
Comprehensive Loss	Comprehensive LossComprehensive loss is comprised of net loss and other comprehensive loss. Other comprehensive loss is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired.
New Accounting Pronouncements	New Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Statements , or ASU No. 2016-13, which requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates , whereby the effective date of this standard for smaller reporting companies was deferred to annual reporting periods beginning after December 15, 2022, including interim periods within those annual reporting periods, and early adoption is still permitted. We are currently evaluating the impact of ASU No. 2016-13 on our consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , or ASU No. 2020-06, which simplifies the guidance on an issuer’s accounting for convertible instruments and contracts in its own equity. The provisions of ASU No. 2020-06 are applicable for fiscal years beginning after December 15, 2023, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. We are currently evaluating the impact of ASU No. 2020-06 on our consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Property and Equipment, Depreciated Periods	Property and equipment are depreciated over the following periods: Computer equipment and software 3 to 5 years Leasehold improvements Shorter of lease term or useful life of asset Furniture and fixtures 7 to 10 years
Schedule of Antidilutive Securities Excluded from Computation of Earnings 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 December 31, 2020 2019 Stock options 12,664,664 9,576,319 Warrants 1,000,000 1,000,000

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation Expense, Related to All Equity Awards	Total stock-based compensation expense, related to all equity awards, comprised the following: Year Ended December 31, 2020 2019 (in thousands) Research and development $ 383 $ 491 General and administrative 1,073 1,642 Total stock-based compensation expense $ 1,456 $ 2,133
Fair Value Stock Options, Weighted-Average Assumptions	We estimate the fair value of stock options at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions: December 31, 2020 2019 Risk-free interest rate 1.0 % 2.3 % Expected annual dividend yield — — Expected stock price volatility 98.3 % 99.4 % Expected term of options 5.7 years 5.9 years
Summary of Stock Option Activity	A summary of our stock option activity for the year ended December 31, 2020 is as follows: Stock Options Weighted- Weighted-Average Aggregate Outstanding at January 1, 2020 9,576,319 $ 4.58 Granted 4,999,811 1.50 Exercised (46,433) 1.83 Forfeited (694,584) 1.26 Expired (1,170,449) 5.17 Outstanding at December 31, 2020 12,664,664 $ 3.51 7.0 $ 6.2 Exercisable at December 31, 2020 8,079,577 $ 4.62 5.6 $ 3.5

Cash, Cash Equivalents and Av_2

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	12 Months Ended
	Dec. 31, 2020
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: December 31, 2020 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 28,593 $ — $ — $ 28,593 Available-for-sale securities: U.S. Treasury securities due in one year or less 5,516 — (1) 5,515 Total available-for-sale securities 5,516 — (1) 5,515 Total cash, cash equivalents and available-for-sale securities $ 34,109 $ — $ (1) $ 34,108 December 31, 2019 Cost Gross Gross Estimated (in thousands) Cash and cash equivalents $ 22,260 $ — $ — $ 22,260 Available-for-sale securities: U.S. Treasury securities due in one year or less 8,244 4 — 8,248 U.S. government-sponsored enterprise obligations due in one year or less 11,928 8 — 11,936 Total available-for-sale securities 20,172 12 — 20,184 Total cash, cash equivalents and available-for-sale securities $ 42,432 $ 12 $ — $ 42,444

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Assets Carried at Fair Value Measured on Recurring Basis	The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2020 and 2019: December 31, 2020 Level 1 Level 2 Level 3 (in thousands) Assets: Cash and cash equivalents $ 28,593 $ — $ — U.S. Treasury securities — 5,515 — Total assets $ 28,593 $ 5,515 $ — Liabilities: Warrant liability $ — $ — $ 198 Total liabilities $ — $ — $ 198 December 31, 2019 Level 1 Level 2 Level 3 (in thousands) Assets: Cash and cash equivalents $ 20,860 $ 1,400 $ — U.S. Treasury securities — 8,248 — U.S. government-sponsored enterprise obligations — 11,936 — Total assets $ 20,860 $ 21,584 $ —

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Schedule of Prepaid and Other Current Assets	Prepaid expenses and other current assets consist of the following: December 31, 2020 2019 (in thousands) Prepaid expenses $ 1,528 $ 1,680 Other current assets 234 457 Restricted cash, current portion 150 — Total prepaid expenses and other current assets $ 1,912 $ 2,137

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consist of the following: December 31, 2020 2019 (in thousands) Computer equipment and software $ 1,893 $ 1,893 Furniture and fixtures 446 446 Leasehold improvements 1,743 1,735 4,082 4,074 Less accumulated depreciation (2,372) (1,888) $ 1,710 $ 2,186

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Summary of Accrued Expenses	Accrued expenses consisted of the following: December 31, 2020 2019 (in thousands) Accrued compensation and benefits $ 2,385 $ 3,055 Accrued clinical and development 3,511 3,793 Liability related to sale of future royalties, net, current portion 848 — Operating lease liability, current portion 489 381 Other 832 848 Total accrued expenses $ 8,065 $ 8,077

Liability Related to Sale of _3

Liability Related to Sale of Future Royalties (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Summary of Applicable Purchaser Expenditures	Pursuant to the HCR Agreement, our sale of the Purchased Assets is subject to an increasing cap amount defined below, which we refer to as the Cap Amount. The Cap Amount is equal to, for each applicable time period specified below, a multiple, as set forth below, of (a) the HCR Closing Date Payment plus (b) 100% of the reasonably incurred Applicable Purchaser Expenditures, as defined below: Time Period Cap Amount From the HCR Closing Date until June 30, 2022 145 % From July 1, 2022 through June 30, 2023 155 % From July 1, 2023 through June 30, 2024 165 % From July 1, 2024 through June 30, 2025 175 %
Schedule of Liability Related to Future Sale of Royalties	The following table shows the activity within the liability account for the year ended December 31, 2020 and 2019: December 31, 2020 2019 (in thousands) Liability related to sale of future royalties - beginning balance $ 29,626 $ — Proceeds from sale of future royalties — 30,000 Debt discount and issuance costs — (2,382) Non-cash royalty revenue (910) (555) Non-cash interest expense recognized 153 2,563 Liability related to sale of future royalties, net - ending balance $ 28,869 $ 29,626 Less: current portion (848) — Liability related to sale of future royalties, net, less current portion $ 28,021 $ 29,626 The following table shows the activity within the liability account from the inception of the BVF Funding Agreement through December 31, 2020: December 31, 2020 (in thousands) Liability related to sale of future royalties to a related party - beginning balance $ — Proceeds from sale of future royalties 20,000 Debt discount and issuance costs (428) Warrant liability (305) Non-cash related party interest expense recognized 2,292 Liability related to sale of future royalties to a related party - ending balance $ 21,559

Liability Related to Sale of _4

Liability Related to Sale of Future Royalties - Related Party Transaction (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Liability Related to Future Sale of Royalties	The following table shows the activity within the liability account for the year ended December 31, 2020 and 2019: December 31, 2020 2019 (in thousands) Liability related to sale of future royalties - beginning balance $ 29,626 $ — Proceeds from sale of future royalties — 30,000 Debt discount and issuance costs — (2,382) Non-cash royalty revenue (910) (555) Non-cash interest expense recognized 153 2,563 Liability related to sale of future royalties, net - ending balance $ 28,869 $ 29,626 Less: current portion (848) — Liability related to sale of future royalties, net, less current portion $ 28,021 $ 29,626 The following table shows the activity within the liability account from the inception of the BVF Funding Agreement through December 31, 2020: December 31, 2020 (in thousands) Liability related to sale of future royalties to a related party - beginning balance $ — Proceeds from sale of future royalties 20,000 Debt discount and issuance costs (428) Warrant liability (305) Non-cash related party interest expense recognized 2,292 Liability related to sale of future royalties to a related party - ending balance $ 21,559

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Summary of Leases	The following is a summary of our current leases included in the respective balance sheet classifications: December 31, 2020 2019 Assets (in thousands) Operating lease right-of-use assets $ 1,419 $ 1,717 Liabilities Accrued expenses and other current liabilities $ 489 $ 381 Operating lease liability 1,436 1,926 Total lease liabilities $ 1,925 $ 2,307
Schedule of Future Minimum Lease Payments	As of December 31, 2020, future minimum lease payments of our operating lease liabilities are as follows: Operating Leases (in thousands) 2021 660 2022 640 2023 658 2024 334 Total future minimum lease payments 2,292 Less: imputed interest (367) Total lease liability $ 1,925

Strategic Agreements (Tables)

Strategic Agreements (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Payments Made to Counterparty, Multiplier	We have the right to extinguish the Interim Obligation by payment to Takeda of an amount equal to (i) the $6.7 million payment multiplied by the multiple set forth in the table below corresponding to the time period in which such extinguishing payment is made, minus (ii) any payments made to Takeda pursuant to the Interim Obligation: Time Period Multiple From the Takeda Amendment Effective Date until June 30, 2022 145 % From July 1, 2022 through June 30, 2023 155 % From July 1, 2023 through June 30, 2024 165 % From July 1, 2024 through June 30, 2025 175 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Tax Benefit or Expense	Our income tax expense for the years ended December 31, 2020 and 2019 differed from the expected U.S. federal statutory income tax expense as set forth below: Years Ended December 31, 2020 2019 (in thousands) Expected federal tax benefit $ (8,503) $ (9,893) Permanent differences 211 352 State taxes, net of the deferred federal benefit (2,563) (2,905) Tax credit carryforwards (837) (738) Adjustments to deferred tax assets and deferred tax liabilities 852 265 Other 69 8 Change in valuation allowance 10,771 12,857 Income tax expense (benefit) $ — $ (54)
Significant Components of Deferred Tax Assets	The significant components of our deferred tax assets and liabilities are as follows: Years Ended December 31, 2020 2019 (in thousands) Deferred tax assets (liabilities): Net operating loss carryforwards $ 151,752 $ 145,024 Tax credit carryforwards 42,645 41,730 Intangible assets 17,028 18,977 Accrued expenses 645 590 Stock-based compensation 4,976 5,661 Sale of future royalties 13,742 8,088 Other (44) (98) Valuation allowance (230,744) (219,972) Net deferred tax assets $ — $ —

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	Feb. 11, 2021USD ($)	Dec. 31, 2020USD ($)Segmentawardfinancial_institutionissuer	Dec. 31, 2019USD ($)
Accounting Policies [Abstract]
Number of operating segments | Segment		1
Cash, cash equivalents and available-for-sale securities		$ 34,109	$ 42,432
Number of major financial institutions | financial_institution		2
Number of issuers of investments | issuer		1
Number of awards with market conditions | award		0
Reclassifications out of accumulated other comprehensive income (loss)		$ 0
Subsequent Event [Line Items]
Sale of stock, consideration received on transaction		$ 7,700
Subsequent Event
Subsequent Event [Line Items]
Sale of stock, consideration received on transaction	$ 86,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property and Equipment, Depreciation Periods (Details)	12 Months Ended
	Dec. 31, 2020
Computer equipment and software | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Computer equipment and software | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	7 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	12,664,664	9,576,319
Warrants
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

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Period$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, net of estimated forfeitures, related to unvested options and restricted stock | $	$ 5,400,000
Unrecognized compensation cost, weighted-average recognition period	3 years 3 months 18 days
Weighted-average fair value per share of options granted (in dollars per share) | $ / shares	$ 1.15	$ 1.07
Related income tax benefits | $	$ 0	$ 0
Stock Incentive Plan, All Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested	25.00%
Remaining percentage of shares vested	75.00%
Vesting period, following first year of service, new employees	3 years
Stock options granted, expiration period (no later than)	10 years
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock Issued pursuant to awards granted (up to) (in shares)	6,031,009
Common stock reserved for issuance upon exercise of outstanding awards (in shares)	5,130,033
Common stock that can be issued pursuant to awards granted (up to) (in shares)	2,084,050
2010 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance upon exercise of outstanding awards (in shares)	7,534,631
2013 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock offering aggregate period	24 months
Number of common stock purchase periods | Period	4
Common stock offering purchase period	6 months
Percentage of common stock purchase price	85.00%
Number of common stock purchased (in shares)	91,696	110,459
Proceeds from purchase of common stock | $	$ 100,000	$ 100,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected annual dividend yield	0.00%	0.00%

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,456	$ 2,133
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	383	491
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,073	$ 1,642

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value Weighted-Average Assumptions, Stock Options (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.00%	2.30%
Expected annual dividend yield	0.00%	0.00%
Expected stock price volatility	98.30%	99.40%
Expected term of options	5 years 8 months 12 days	5 years 10 months 24 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Stock Options
Outstanding at beginning of period (in shares) | shares	9,576,319
Granted (in shares) | shares	4,999,811
Exercised (in shares) | shares	(46,433)
Forfeited (in shares) | shares	(694,584)
Expired (in shares) | shares	(1,170,449)
Outstanding at end of period (in shares) | shares	12,664,664
Exercisable at end of period (in shares) | shares	8,079,577
Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 4.58
Granted (in dollars per share) | $ / shares	1.50
Exercised (in dollars per share) | $ / shares	1.83
Forfeited (in dollars per share) | $ / shares	1.26
Expired (in dollars per share) | $ / shares	5.17
Outstanding at end of period (in dollars per share) | $ / shares	3.51
Exercisable at end of period (in dollars per share) | $ / shares	$ 4.62
Weighted-Average Remaining Contractual Life (years)
Outstanding at end of period	7 years
Exercisable at end of period	5 years 7 months 6 days
Aggregate Intrinsic Value (in millions)
Outstanding at end of period | $	$ 6.2
Exercisable at end of period | $	$ 3.5

Cash, Cash Equivalents and Av_3

Cash, Cash Equivalents and Available-for-Sale Securities - Summary of Activity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, Cost	$ 28,593	$ 22,260
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	28,593	22,260
Total available-for-sale securities, Cost	5,516	20,172
Total available-for-sale securities, Gross Unrealized Gains	0	12
Total available-for-sale securities, Gross Unrealized Losses	(1)	0
Total available-for-sale securities, Estimated Fair Value	5,515	20,184
Total cash, cash equivalents and available-for-sale securities, Cost	34,109	42,432
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Gains	0	12
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Losses	(1)	0
Total cash, cash equivalents and available-for-sale securities, Estimated Fair Value	34,108	42,444
U.S. Treasury securities due in one year or less
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, Cost	5,516	8,244
Available-for-sale securities, Gross Unrealized Gains	0	4
Available-for-sale securities, Gross Unrealized Losses	(1)	0
Available-for-sale securities, Estimated Fair Value	$ 5,515	8,248
U.S. government-sponsored enterprise obligations due in one year or less
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, Cost		11,928
Available-for-sale securities, Gross Unrealized Gains		8
Available-for-sale securities, Gross Unrealized Losses		0
Available-for-sale securities, Estimated Fair Value		$ 11,936

Cash, Cash Equivalents and Av_4

Cash, Cash Equivalents and Available-for-Sale Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)SecurityFacility	Dec. 31, 2019USD ($)
Debt Securities, Available-for-sale [Line Items]
Number of debt securities, unrealized loss position, less than 12 months | Security	3
Unrealized loss position, less than 12 months, fair value	$ 4,500,000
Material realized gain (loss)	0	$ 0
Other-than-temporary impairments recognized in earnings	$ 0	$ 0
Foreign Financial Institution and Other Corporate Debt Securities
Debt Securities, Available-for-sale [Line Items]
Number of securities in foreign financial institutions | Facility	0

Fair Value - Assets Carried at

Fair Value - Assets Carried at Fair Value Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value	$ 5,515	$ 8,248
U.S. government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value		11,936
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	28,593	20,860
Total assets	28,593	20,860
Warrant liability	0
Total liabilities	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	1,400
Total assets	5,515	21,584
Warrant liability	0
Total liabilities	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total assets	0	0
Warrant liability	198
Total liabilities	198
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value	0	0
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value	5,515	8,248
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value	$ 0	0
Fair Value, Measurements, Recurring | U.S. government-sponsored enterprise obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value		0
Fair Value, Measurements, Recurring | U.S. government-sponsored enterprise obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value		11,936
Fair Value, Measurements, Recurring | U.S. government-sponsored enterprise obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, debt maturities, next twelve months, fair value		$ 0

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	$ 5,515,000	$ 20,184,000
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	$ 0

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 1,528	$ 1,680
Other current assets	234	457
Restricted cash, current portion	150	0
Total prepaid expenses and other current assets	$ 1,912	$ 2,137

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 4,082	$ 4,074
Less accumulated depreciation	(2,372)	(1,888)
Property, plant and equipment, net	1,710	2,186
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,893	1,893
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	446	446
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,743	$ 1,735

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 2,385	$ 3,055
Accrued clinical and development	3,511	3,793
Liability related to sale of future royalties, net, current portion	848	0
Operating lease liability, current portion	489	381
Other	832	848
Total accrued expenses	$ 8,065	$ 8,077
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent

Liability Related to Sale of _5

Liability Related to Sale of Future Royalties - Additional Information (Details) - HealthCare Royalty Partners III, L.P. - USD ($) $ in Millions	Mar. 11, 2019	Mar. 05, 2019	Dec. 31, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Closing day payment	$ 30
Gross proceeds	22.5
Net proceeds	$ 20.9
Percentage of applicable purchaser expenditures		100.00%
Percentage of payments made to counterparty		100.00%
Deferred transaction costs amortized			$ 2.4

Liability Related to Sale of _6

Liability Related to Sale of Future Royalties - Applicable Purchaser Expenditures (Details) - HealthCare Royalty Partners III, L.P.	Mar. 05, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
From the HCR Closing Date until June 30, 2022	145.00%
From July 1, 2022 through June 30, 2023	155.00%
From July 1, 2023 through June 30, 2024	165.00%
From July 1, 2024 through June 30, 2025	175.00%

Liability Related to Sale of _7

Liability Related to Sale of Future Royalties - Liability Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability Related To Future Sale Of Royalties [Roll Forward]
Non-cash royalty revenue	$ (910)	$ (555)
Non-cash interest expense	153	2,563
Less: current portion	(848)	0
Liability related to sale of future royalties, net, less current portion	28,021	29,626
Royalty revenue
Liability Related To Future Sale Of Royalties [Roll Forward]
Non-cash royalty revenue	(910)	(555)
HCR Agreement
Liability Related To Future Sale Of Royalties [Roll Forward]
Liability related to sale of future royalties - beginning balance	29,626	0
Proceeds from sale of future royalties	0	30,000
Debt discount and issuance costs	0	(2,382)
Liability related to sale of future royalties, net - ending balance	28,869	29,626
Less: current portion	(848)	0
Liability related to sale of future royalties, net, less current portion	$ 28,021	$ 29,626

Liability Related to Sale of _8

Liability Related to Sale of Future Royalties - Related Party Transaction - Additional Information (Details) $ / shares in Units, $ in Thousands	Jan. 08, 2020USD ($)day$ / sharesshares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Non-cash related party interest expense		$ (2,292)	$ 0
Number of warrants issued (in shares) | shares		0
Biotechnology Value Fund, L.P. | Infinity Pharmaceuticals
Debt Instrument [Line Items]
Ownership percentage, noncontrolling interest	30.00%
BVF Funding Agreement
Debt Instrument [Line Items]
Common stock, minimum value per share (in dollars per share) | $ / shares	$ 5
Warrant threshold, sale of stock, number of shares in transaction (in shares) | shares	8,554,345
Warrant threshold, price per share (in dollars per share) | $ / shares	$ 3.75
BVF Funding Agreement | Infinity Pharmaceuticals | Holdco
Debt Instrument [Line Items]
Option to purchase, percentage of outstanding equity interests	100.00%
BVF Funding Agreement | BVF And Royalty Security, LLC
Debt Instrument [Line Items]
Upfront purchase price	$ 20,000
Milestone payment	$ 5,000
Common stock, trading days | day	20
Option premium, percentage accrued per annum	10.00%
Option premium, percentage accruing after trigger event	20.00%
Deferred transaction costs amortized	$ 400
Warrant liability	$ 300
Effective annual interest rate	11.00%
Period after closing date	36 months
Percentage of common stock called by warrant	50.00%
Exercise price of warrant, percentage of price per share	150.00%
Novation and Amendment Agreement | BVF And Royalty Security, LLC
Debt Instrument [Line Items]
Period after initial stock issuance	6 months

Liability Related to Sale of _9

Liability Related to Sale of Future Royalties - Related Party Transaction - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability Related To Future Sale Of Royalties [Roll Forward]
Non-cash related party interest expense recognized	$ 2,292	$ 0
BVF Funding Agreement
Liability Related To Future Sale Of Royalties [Roll Forward]
Liability related to sale of future royalties to a related party - beginning balance	0
Proceeds from sale of future royalties	20,000
Debt discount and issuance costs	(428)
Warrant liability	(305)
Non-cash related party interest expense recognized	2,292
Liability related to sale of future royalties to a related party - ending balance	$ 21,559	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	12 Months Ended					48 Months Ended
	Dec. 31, 2020USD ($)	Jul. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Aug. 31, 2019USD ($)ft²	Aug. 31, 2018USD ($)	Aug. 01, 2024	Apr. 03, 2019USD ($)ft²
Operating Leased Assets [Line Items]
Option to extend, term	2 years
Weighted average remaining lease term	3 years 6 months		4 years 6 months
Weighted average discount rate	10.00%		10.00%
Operating lease costs	$ 700,000		$ 800,000
Lease payments	700,000		$ 400,000
784 Memorial Drive Premises | Sublease Agreement
Operating Leased Assets [Line Items]
Area of premises subleased under lease agreement | ft²				6,091
Monthly base rent expense				$ 20,303	$ 19,796
1100 Massachusetts Avenue, Cambridge, Massachusetts | Lease Agreements
Operating Leased Assets [Line Items]
Monthly base rent expense		$ 47,961
Area of premises leased under lease agreement | ft²							10,097
Lease term							5 years
Restricted cash, less current portion	$ 15,000
Leasehold improvements							$ 600,000
Forecast | 1100 Massachusetts Avenue, Cambridge, Massachusetts | Lease Agreements
Operating Leased Assets [Line Items]
Annual percentage increase of rent expense						3.00%
Letter of Credit | 1100 Massachusetts Avenue, Cambridge, Massachusetts | Lease Agreements
Operating Leased Assets [Line Items]
Security deposit							300,000
Security deposit, reduced amount under lease term							$ 150,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating lease right-of-use assets	$ 1,419	$ 1,717
Liabilities
Accrued expenses and other current liabilities	489	381
Operating lease liability	1,436	1,926
Total lease liabilities	$ 1,925	$ 2,307

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2020	$ 660
2021	640
2022	658
2023	334
Total future minimum lease payments	2,292
Less: imputed interest	(367)
Total lease liability	$ 1,925	$ 2,307

Strategic Agreements - Addition

Strategic Agreements - Additional Information (Details)	Mar. 04, 2019USD ($)	Oct. 31, 2019USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2020USD ($)Product	Dec. 31, 2019USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue				$ 1,719,000	$ 3,049,000
Royalty expense				1,037,000	7,308,000
Research and development				$ 26,761,000	27,116,000
Number of distinct product candidates | Product				1
Trailing Mundipharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty percentage on sales, reimbursement of research and development, percentage				4.00%
Royalty payments, reimbursement of research and development upon completion				$ 260,000,000
Royalty percentage on sales, reimbursement of research and development upon completion, percentage				1.00%
Royalty payments, reimbursement of research and development				$ 1,400,000
PellePharm Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue					2,000,000
PellePharm Agreement | Hedgehog Products
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Remaining milestone payment amount (up to)			$ 9,000,000
Additional milestone payment amount, upon achievement of certain annual net sales thresholds			$ 37,500,000
Takeda Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 2,000,000
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Approval and commercialization cost of distinct products payable (up to)				165,000,000
Current | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Success-based remaining milestone payments				3,000,000
Takeda | Takeda Agreement, Fourth Amendment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Investment amount to be paid	$ 6,700,000
Percentage of total consideration and milestone payments to be received	25.00%
Percentage of net expenses incurred	25.00%
Percentage of royalty payments	25.00%
Royalty expense					6,700,000
Interim obligation amount paid				$ 200,000	$ 100,000

Strategic Agreements - Takeda A

Strategic Agreements - Takeda Agreement (Details) - Takeda	Mar. 04, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
From the Takeda Amendment Effective Date until June 30, 2022	145.00%
From July 1, 2022 through June 30, 2023	155.00%
From July 1, 2023 through June 30, 2024	165.00%
From July 1, 2024 through June 30, 2025	175.00%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Income tax expense (benefit)	$ 0	$ (54,000)
Increase in valuation allowance against deferred tax assets	10,800,000	12,900,000
Unrecognized tax benefits	0	0
Interest and penalties accrued	0	0
Interest and penalties expensed	0	$ 0
Federal
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Operating loss carry-forward, net	582,900,000
Operating loss carryforward, not subject to expiration	58,200,000
Tax credit carry-forward amount	$ 34,800,000
Tax credit carry-forward, expiration date	2040
State
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Operating loss carry-forward, net	$ 464,200,000
Tax credit carry-forward amount	$ 9,900,000
Tax credit carry-forward, expiration date	2034

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Expected federal tax benefit	$ (8,503,000)	$ (9,893,000)
Permanent differences	211,000	352,000
State taxes, net of the deferred federal benefit	(2,563,000)	(2,905,000)
Tax credit carryforwards	(837,000)	(738,000)
Adjustments to deferred tax assets and deferred tax liabilities	852,000	265,000
Other	69,000	8,000
Change in valuation allowance	10,771,000	12,857,000
Income tax expense (benefit)	$ 0	$ (54,000)

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets (liabilities):
Net operating loss carryforwards	$ 151,752	$ 145,024
Tax credit carryforwards	42,645	41,730
Intangible assets	17,028	18,977
Accrued expenses	645	590
Stock-based compensation	4,976	5,661
Sale of future royalties	13,742	8,088
Other	(44)	(98)
Valuation allowance	(230,744)	(219,972)
Net deferred tax assets	$ 0	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	Jul. 29, 2019	Feb. 24, 2014	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2020	May 31, 2020
Equity [Abstract]
Sales agreement, aggregate offering price (up to)	$ 20,000,000
Sales agreement, commission percentage	3.00%
Sale of stock, number of shares issued in transaction (in shares)			6,725,691	0
Sale of stock, price per share (in dollars per share)			$ 1.17
Sale of stock, consideration received on transaction			$ 7,700,000
Common stock, shares authorized (in shares)			200,000,000	100,000,000	200,000,000	100,000,000
Common stock warrants issued (in shares)		1,000,000
Common stock warrants issued, exercise price (in dollars per share)		$ 13.83
Potential percentage of ownership interest (in excess of)		9.985%
Warrants, exercised (in shares)			0

Defined Contribution Benefit _2

Defined Contribution Benefit Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Participant contributions, employee	6.00%	6.00%
Employer matching contribution	$ 0.2	$ 0.2

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 11, 2021	Dec. 31, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Sale of stock, number of shares issued in transaction (in shares)		6,725,691	0
Sale of stock, price per share (in dollars per share)		$ 1.17
Sale of stock, consideration received on transaction		$ 7.7
Subsequent Event
Subsequent Event [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	24,150,000
Sale of stock, over-allotment option, percentage	15.00%
Sale of stock, price per share (in dollars per share)	$ 3.80
Sale of stock, gross proceeds received on transaction	$ 91.8
Sale of stock, consideration received on transaction	$ 86
Subsequent Event | Over-Allotment Option
Subsequent Event [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	3,150,000