Rein Therapeutics (RNTX) 10-Q 12 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 11, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	ALRN
Entity Registrant Name	Aileron Therapeutics Inc
Entity Central Index Key	0001420565
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		40,684,649
Entity File Number	001-38130
Entity Tax Identification Number	13-4196017
Entity Address, Address Line One	490 Arsenal Way
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	617
Local Phone Number	995-0900
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 7,850	$ 5,311
Investments	6,271	12,967
Prepaid expenses and other current assets	1,828	1,247
Restricted cash	25	25
Total current assets	15,974	19,550
Operating lease, right-of-use asset	5,550	6,060
Property and equipment, net	147	295
Restricted cash, non-current	568	568
Total assets	22,239	26,473
Current liabilities:
Accounts payable	1,002	1,452
Accrued expenses and other current liabilities	3,687	3,941
Paycheck Protection Program loan, current portion	48
Operating lease liability, current portion	512	446
Total current liabilities	5,249	5,839
Paycheck Protection Program loan, net of current portion	336
Operating lease liability, net of current portion	4,196	4,586
Total liabilities	9,781	10,425
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized and no shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively
Common stock, $0.001 par value; 150,000,000 shares authorized at September 30, 2020 and December 31, 2019; 39,874,847 and 27,810,358 shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively	40	28
Additional paid-in capital	226,715	214,148
Accumulated other comprehensive gain/(loss)	(1)	7
Accumulated deficit	(214,296)	(198,135)
Total stockholders’ equity	12,458	16,048
Total liabilities and stockholders’ equity	$ 22,239	$ 26,473

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	39,874,847	27,810,358
Common stock, shares outstanding	39,874,847	27,810,358

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 0	$ 0	$ 0	$ 0
Operating expenses:
Research and development	2,684	4,475	9,241	12,953
General and administrative	2,344	3,440	7,063	9,654
Total operating expenses	5,028	7,915	16,304	22,607
Loss from operations	(5,028)	(7,915)	(16,304)	(22,607)
Gain on sale of property and equipment			66
Interest income	5	166	77	473
Net loss	$ (5,023)	$ (7,749)	$ (16,161)	$ (22,134)
Net loss per share — basic and diluted	$ (0.13)	$ (0.28)	$ (0.49)	$ (0.95)
Weighted average common shares outstanding—basic and diluted	39,321,177	27,810,358	32,808,082	23,431,823
Comprehensive loss:
Net loss	$ (5,023)	$ (7,749)	$ (16,161)	$ (22,134)
Other comprehensive gain (loss):
Unrealized gain (loss) on investments, net of tax of $0	1	(7)	(8)	22
Total other comprehensive gain (loss)	1	(7)	(8)	22
Total comprehensive loss	$ (5,022)	$ (7,756)	$ (16,169)	$ (22,112)

Condensed Statements of Opera_2

Condensed Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Unrealized gain (loss) on investments, tax	$ 0	$ 0	$ 0	$ 0

Condensed Statement of Stockhol

Condensed Statement of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock and Common Warrants [Member]	Pre-funded Warrants and Common Warrants [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Common Stock [Member]Common Stock and Common Warrants [Member]	Common Stock [Member]Pre-funded Warrants and Common Warrants [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Common Stock and Common Warrants [Member]	Additional Paid-in Capital [Member]Pre-funded Warrants and Common Warrants [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning balance at Dec. 31, 2018	$ 19,600			$ (273)	$ 15			$ 188,083			$ (5)	$ (168,493)	$ (273)
Beginning balance, shares at Dec. 31, 2018					14,748,475
Accounting Standards Update [Extensible List]				us-gaap:AccountingStandardsUpdate201602Member
Exercise of stock options	165							165
Exercise of stock options, shares					126,560
Stock-based compensation expense	563							563
Unrealized gain (loss) on investments	5										5
Net loss	(7,213)											(7,213)
Ending balance at Mar. 31, 2019	12,847				$ 15			188,811				(175,979)
Ending balance, shares at Mar. 31, 2019					14,875,035
Beginning balance at Dec. 31, 2018	19,600			$ (273)	$ 15			188,083			(5)	(168,493)	$ (273)
Beginning balance, shares at Dec. 31, 2018					14,748,475
Unrealized gain (loss) on investments	22
Net loss	(22,134)
Ending balance at Sep. 30, 2019	22,816				$ 28			213,671			17	(190,900)
Ending balance, shares at Sep. 30, 2019					27,810,358
Beginning balance at Mar. 31, 2019	12,847				$ 15			188,811				(175,979)
Beginning balance, shares at Mar. 31, 2019					14,875,035
Stock issued during period, value		$ 21,622	$ 2,203			$ 12	$ 1		$ 21,610	$ 2,202
Stock issued during period, shares						11,838,582	1,096,741
Stock-based compensation expense	460							460
Unrealized gain (loss) on investments	24										24
Net loss	(7,172)											(7,172)
Ending balance at Jun. 30, 2019	29,984				$ 28			213,083			24	(183,151)
Ending balance, shares at Jun. 30, 2019					27,810,358
Exercise of pre-funded warrants	11							11
Stock issuance costs	(37)							(37)
Stock-based compensation expense	614							614
Unrealized gain (loss) on investments	(7)										(7)
Net loss	(7,749)											(7,749)
Ending balance at Sep. 30, 2019	22,816				$ 28			213,671			17	(190,900)
Ending balance, shares at Sep. 30, 2019					27,810,358
Beginning balance at Dec. 31, 2019	$ 16,048				$ 28			214,148			7	(198,135)
Beginning balance, shares at Dec. 31, 2019	27,810,358				27,810,358
Stock issuance costs	$ (28)							(28)
Stock-based compensation expense	505							505
Unrealized gain (loss) on investments	(8)										(8)
Net loss	(6,748)											(6,748)
Ending balance at Mar. 31, 2020	9,769				$ 28			214,625			(1)	(204,883)
Ending balance, shares at Mar. 31, 2020					27,810,358
Beginning balance at Dec. 31, 2019	$ 16,048				$ 28			214,148			7	(198,135)
Beginning balance, shares at Dec. 31, 2019	27,810,358				27,810,358
Unrealized gain (loss) on investments	$ (8)
Net loss	(16,161)
Ending balance at Sep. 30, 2020	$ 12,458				$ 40			226,715			(1)	(214,296)
Ending balance, shares at Sep. 30, 2020	39,874,847				39,874,847
Beginning balance at Mar. 31, 2020	$ 9,769				$ 28			214,625			(1)	(204,883)
Beginning balance, shares at Mar. 31, 2020					27,810,358
Stock issued during period, value	10,729				$ 11			10,718
Stock issued during period, shares					11,425,118
RSUs vested, net of shares repurchased for tax	(13)							(13)
RSUs vested, net of shares repurchased for tax, shares					26,100
Stock-based compensation expense	560							560
Unrealized gain (loss) on investments	(1)										(1)
Net loss	(4,390)											(4,390)
Ending balance at Jun. 30, 2020	16,654				$ 39			225,890			(2)	(209,273)
Ending balance, shares at Jun. 30, 2020					39,261,576
Stock issued during period, value	364				$ 1			363
Stock issued during period, shares					606,747
RSUs vested, net of shares repurchased for tax	(3)							(3)
RSUs vested, net of shares repurchased for tax, shares					6,524
Stock-based compensation expense	465							465
Unrealized gain (loss) on investments	1										1
Net loss	(5,023)											(5,023)
Ending balance at Sep. 30, 2020	$ 12,458				$ 40			$ 226,715			$ (1)	$ (214,296)
Ending balance, shares at Sep. 30, 2020	39,874,847				39,874,847

Condensed Statement of Stockh_2

Condensed Statement of Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Jun. 30, 2019USD ($)
Common Stock and Common Warrants [Member]
Sale of common stock and common warrants, Issuance costs	$ 2,175

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (16,161)	$ (22,134)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	153	80
Net amortization of premiums and discounts on investments	(19)	(170)
Stock-based compensation expense	1,530	1,637
Gain on sale of property and equipment	(66)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(580)	(871)
Other assets	510	852
Accounts payable	(451)	603
Operating lease liabilities	(325)	(267)
Accrued expenses and other current liabilities	(378)	101
Net cash used in operating activities	(15,787)	(20,169)
Cash flows from investing activities:
Purchases of property and equipment	(5)	(136)
Proceeds from sale of property and equipment	66
Purchases of investments	(8,035)	(24,510)
Proceeds from sales or maturities of investments	14,742	17,068
Net cash provided by (used in) investing activities	6,768	(7,578)
Cash flows from financing activities:
Proceeds from issuance of common stock and common warrants and pre-funded warrants, net of issuance costs	11,174	23,814
Proceeds from Paycheck Protection Program Loan	384
Proceeds from exercise of stock options		165
Net cash provided by financing activities	11,558	23,979
Net increase/(decrease) in cash, cash equivalents and restricted cash	2,539	(3,768)
Cash, cash equivalents and restricted cash at beginning of period	5,904	11,228	$ 11,228
Cash, cash equivalents and restricted cash at end of period	8,443	$ 7,460	$ 5,904
Supplemental disclosure of non-cash financing activities:
Common stock issuance costs included in accounts payable and accrued expenses	$ 127

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Aileron Therapeutics, Inc. (“Aileron” or the “Company”) is a clinical stage biopharmaceutical company that is focused on transforming the experience of chemotherapy for cancer patients, enabling them to fight cancer without the fear or burden of chemotherapy-induced side effects. ALRN-6924, the Company’s first-in-class MDM2/MDMX dual inhibitor activating p53, is the only reported therapeutic agent in clinical development to employ a biomarker strategy, in which the Company exclusively focuses on treating patients with p53-mutated cancers. With this unique, targeted strategy, ALRN-6924 is designed to protect multiple healthy cell types throughout the body from chemotherapy while chemotherapy continues to destroy cancer cells. In addition to potentially reducing or eliminating multiple side effects, ALRN-6924 may also improve patients’ quality of life and help them better tolerate chemotherapy, potentially allowing patients to complete their treatment without dose reductions or delays. The Company’s long-term vision is to provide chemoprotection for patients with p53-mutated cancers, which represents approximately 50% of cancer patients, regardless of cancer type or chemotherapeutic drug. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations, uncertainties in the clinical development of product candidates and in the ability to obtain needed additional financing. ALRN-6924 will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. ALRN-6924, the Company’s product candidate, is in clinical development. There can be no assurance that the Company’s development of ALRN-6924 will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that ALRN-6924 will obtain necessary governmental regulatory approval or, if approved, will be commercially viable. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its key employees and consultants. The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Liquidity In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern In September 2020, the Company entered into a purchase agreement (“Purchase Agreement”) with Lincoln Park Capital Fund, LLC (“LPC”). The Purchase Agreement provides that, subject to the terms and conditions set forth therein, the Company may sell, at its discretion, to LPC up to $15,000 of shares of common stock during the term of the Purchase Agreement. In connection with the execution of the Purchase Agreement on September 21, 2020, LPC made an initial purchase at market price of $500 of common stock at $1.36 per share and the Company issued an additional 367,647 shares to LPC as consideration to LPC for its commitment to purchase shares under the Purchase Agreement. Subject to certain limitations, the Company has the right, but not the obligation, to sell to LPC up to an additional $14,500 in shares of common stock over a thirty-six-month period that commenced in October 2020. The purchase price per share of the shares sold will be based on the market prices prevailing immediately preceding the time of sale as computed under the Purchase Agreement. There are no upper limits to the price LPC may pay to purchase common stock from the Company. LPC has agreed not to cause or engage in any manner whatsoever, any direct or indirect short selling or hedging of the Company’s shares of common stock. The agreement may be terminated by the Company at any time, at its sole discretion, without any additional cost or penalty. In June 2020, the Company issued and sold in an underwritten public offering an aggregate of 10,162,059 shares of common stock, including an additional 1,071,149 shares of common stock upon the partial exercise of an option of the underwriters to purchase additional shares, for a purchase price to the public of $1.10 per share. The Company received aggregate gross proceeds from the public offering of approximately $11,178 before deducting underwriting discounts and commissions and offering expenses of $932. In July 2019, the Company entered into a Capital on Demand SM On April 2, 2019, the Company issued and sold in a private placement an aggregate of (i) 11,838,582 units, consisting of 11,838,582 shares of its common stock and associated warrants (the “common warrants”) to purchase an aggregate of 11,838,582 shares of common stock, for a combined price of $2.01 per unit and (ii) 1,096,741 units, consisting of (a) pre-funded warrants to purchase 1,096,741 shares of the Company’s common stock and (b) associated common warrants to purchase 1,096,741 shares of common stock, for a combined price of $2.01 per unit. The pre-funded warrants had an exercise price of $0.01 per share and had no expiration. The common warrants are exercisable at an exercise price of $2.00 per share and expire five years from the date of issuance. The securities were sold pursuant to a securities purchase agreement entered into with accredited investors on March 28, 2019. The Company received aggregate gross proceeds from the private placement of approximately $26,000, before deducting placement agent fees and offering expenses of $2,175 and excluding the exercise of any warrants. In July 2019, all outstanding pre-funded warrants were exercised for 1,096,741 shares of common stock. The Company’s interim financial statements have been prepared on a going concern basis, which contemplates the continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. Through September 30, 2020, the Company has funded its operations primarily through sales of common stock in its initial public offering and a follow-on public offering, sales of common stock in an “at-the-market” offering, sales of common stock under an equity line with LPC, sales of common stock and warrants in a private placement, sales of preferred stock prior to the Company’s initial public offering and payments received under a collaboration agreement. As of September 30, 2020, the Company had cash, cash equivalents and investments of $14,121. The Company has incurred losses and negative cash flows from operations and had an accumulated deficit of $214,296 as of September 30, 2020. The Company expects to continue to generate losses for the foreseeable future. As of November 12, 2020, the date of issuance of these unaudited interim condensed financial statements, the Company expects that its cash, cash equivalents and investments To execute its business plans, the Company will need substantial funding to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through the sale of common stock in public offerings and/or private placements, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may not be able to obtain financing when needed, on acceptable terms or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its clinical programs, product portfolio expansion plans or commercialization efforts, which could adversely affect its business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of common stock and stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning the COVID-19 pandemic and the actions taken to contain or treat COVID-19, as well as the economic impact on local, regional, national and international markets. The Company has made estimates of the impact of COVID-19 within its financial statements and there may be changes to those estimates in future periods. Unaudited Interim Financial Information The accompanying unaudited condensed financial statements as of September 30, 2020 and for the nine months ended September 30, 2020 and 2019 have been prepared by the Company pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 that was filed with the SEC on March 30, 2020. The unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2020, the results of its operations for the three and nine months ended September 30, 2020 and 2019 and its cash flows for the nine months ended September 30, 2020 and 2019. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2020 and 2019 are unaudited. The results for the nine months ended September 30, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2019 has been derived from the Company’s audited financial statements for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 30, 2020. Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market accounts, corporate notes and commercial paper, are stated at fair value. Restricted Cash As of September 30, 2020 and December 31, 2019, current restricted cash consisted of $25 of cash deposited in a separate restricted bank account as a security deposit for the Company’s corporate credit cards. As of September 30, 2020 and December 31, 2019, non-current restricted cash consisted of $568 of cash deposited in a separate restricted bank account as a security deposit for Investments The Company classifies its available-for-sale debt security investments as current assets on the balance sheet if they mature within one year from the balance sheet date. The Company classifies its investments as available-for-sale securities. The Company’s investments are measured and reported at fair value using quoted prices in active markets for similar securities or using other inputs that are observable or can be corroborated by observable market data. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit). The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the statements of operations and comprehensive loss. The Company evaluates its investments with unrealized losses for other-than-temporary impairment. When assessing investments for other-than-temporary declines in value, the Company considers such factors as, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general, among other factors. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable. • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts payable and accrued expenses approximate their fair value due to the short-term nature of these liabilities. Net Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) is computed by adjusting income (loss) per share to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of shares of common stock outstanding for the period, including potential dilutive common shares. For purpose of this calculation, outstanding options, restricted stock units and warrants to purchase common stock are considered potential dilutive common shares. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. Risks and Uncertainties In December 2019, an outbreak of respiratory illness caused by a strain of novel coronavirus, COVID-19, began in China. That outbreak has led to numerous confirmed cases worldwide, including in the United States and other countries where the Company is conducting clinical trials or activities in support thereof. The World Health Organization declared the outbreak a global pandemic on March 11, 2020. The impact of this pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. Potential impacts to the Company’s the Company’s the Company believes its the Company’s its the Company has the Company’s Any negative impact that the COVID-19 outbreak has on the ability of the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s Recently Adopted Accounting Pronouncements Fair Value of Financial Instruments In This ASU removes the requirement to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy; the policy for timing of transfers between levels; and the valuation processes for Level 3 fair value measurements Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates

Fair Value of Financial Assets

Fair Value of Financial Assets	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets	3. Fair Value of Financial Assets The following tables present information about the Company’s assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of September 30, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 3,362 $ — $ — $ 3,362 Government sponsored enterprises — 500 — 500 Corporate notes — 1,000 — 1,000 Commercial paper — 1,500 — 1,500 Investments: Treasury bills — 2,749 — 2,749 Agency bonds — 3,522 — 3,522 $ 3,362 $ 9,271 $ — $ 12,633 Fair Value Measurements as of December 31, 2019 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 4,208 $ — $ — $ 4,208 Investments: Corporate notes — 5,491 — 5,491 Commercial paper — 7,476 — 7,476 $ 4,208 $ 12,967 $ — $ 17,175 As of September 30, 2020 and December 31, 2019, the Company’s cash equivalents and investments were valued based on Level 1 and Level 2 inputs. In determining the fair value of its corporate notes and commercial paper at each date presented above, the Company relied on quoted prices for similar securities in active markets or using other inputs that are observable or can be corroborated by observable market data. The Company’s cash equivalents have original maturities of less than 90 days from the date of purchase. All available-for-sale investments have contractual maturities of less than one year. During the nine months ended September 30, 2020 and the year ended December 31, 2019, there were no transfers in and out of Level 3.

Investments

Investments	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Investments	4. Investments As of September 30, 2020 and December 31, 2019, the fair value of available-for-sale investments by type of security was as follows: September 30, 2020 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Agency bonds $ 3,522 $ — $ — $ 3,522 Treasury bills 2,749 — — 2,749 $ 6,271 $ — $ — $ 6,271 December 31, 2019 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Corporate notes $ 5,489 $ 2 $ — $ 5,491 Commercial paper 7,470 6 — 7,476 $ 12,959 $ 8 $ — $ 12,967

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following: September 30, 2020 December 31, 2019 Laboratory equipment $ 406 $ 451 Computer equipment and software 181 177 Furniture and fixtures 189 189 776 817 Less: Accumulated depreciation and amortization (629 ) (522 ) $ 147 $ 295 Depreciation and amortization expense for the nine months ended September 30, 2020 was $153. During the nine months ended September 30, 2020, fully depreciated assets with a cost of $45 was sold for $66, resulting in a gain of $66. During the year ended December 31, 2019, fully depreciated assets with a cost of $723 were disposed of for no proceeds, resulting in neither a gain nor a loss. However, assets with a cost of $26 and accumulated depreciation of $21 were disposed of for no proceeds, resulting in a loss on disposal of $5.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: September 30, 2020 December 31, 2019 External research and development services $ 1,973 $ 1,673 Payroll and payroll-related costs 945 1,281 Professional fees 490 635 Other 279 352 $ 3,687 $ 3,941

Paycheck Protection Loan

Paycheck Protection Loan	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Paycheck Protection Loan	7. Paycheck Protection Loan On April 30, 2020, the Company received loan proceeds in the amount of approximately $384 under the Paycheck Protection Program (“PPP”). The PPP, established as part of the Coronavirus Aid, Relief and Economic Security Act (“CARES Act”), provides for loans to qualifying businesses for amounts up to 2.5 times of the average monthly payroll expenses of the qualifying business. The loan and accrued interest are forgivable after eight weeks if the borrower uses the loan proceeds for eligible purposes, including payroll, benefits, rent and utilities. The amount of loan forgiveness may be reduced if the borrower terminates employees or reduces salaries during the eight-week period. The unforgiven portion of the PPP loan is payable over two years at an interest rate of 1%, with a deferral of payments for the first six months. The Company used the proceeds for purposes consistent with the PPP. The Company has determined to account for the PPP loan as debt under Accounting Standards Update (“ASC 470”), “Debt”, and has allocated and recorded the loan proceeds between current and non-current liabilities. The Company further determined that loan forgiveness would become probable of occurring upon acceptance by the Small Business Association of the Company’s forgiveness application. If and when the loan forgiveness becomes probable, the Company will recognize income for debt extinguishment pursuant to ASC 470-50-15-4.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity In September of 2020, the Company entered into the Purchase Agreement with LPC. In connection with the execution of the Purchase Agreement on September 21, 2020, LPC made an initial purchase of $500 of common stock at $1.36 per share and the Company issued an additional 367,647 shares to LPC as consideration to LPC for its commitment to purchase shares under the Purchase Agreement. Subject to certain limitations, the Company has the right, but not the obligation, to sell to LPC up to an additional $14,500 in shares of common stock over a thirty-six-month period that commenced in October 2020. The purchase price per share of the shares sold will be based on the market prices prevailing immediately preceding the time of sale as computed under the Purchase Agreement. There are no upper limits to the price LPC may pay to purchase common stock from the Company. LPC has agreed not to cause or engage in any manner whatsoever, any direct or indirect short selling or hedging of the Company’s shares of common stock. The agreement may be terminated by the Company at any time, at its sole discretion, without any additional cost or penalty. In June 2020, the Company issued and sold in an underwritten public offering an aggregate of 10,162,059 shares of common stock, including an additional 1,071,149 shares of common stock upon the partial exercise of an option of the underwriter to purchase additional shares, for a purchase price to the public of $1.10 per share. The Company received aggregate gross proceeds from the public offering of approximately $11,178, before deducting underwriting discounts and commissions and offering expenses of $932. In July 2019, the Company entered into the Sales Agreement with JonesTrading, under which the Company currently may issue and sell shares of common stock, having an aggregate offering price of up to $15,000. Sales of common stock through JonesTrading may be made by any method that is deemed an “at the market” offering as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. The Company is not obligated to make any sales of its common stock under the Sales Agreement. The Company began selling shares of common stock under the Sales Agreement in April 2020. During the nine months ended September 30, 2020 the Company issued and sold an aggregate of 1,281,571 shares of common stock pursuant to the Sales Agreement for gross proceeds of $785, before deducting commissions and fees of $24. On April 2, 2019, the Company issued and sold in a private placement an aggregate of (i) 11,838,582 units, consisting of 11,838,582 shares of its common stock and associated warrants, (the “common warrants”), to purchase an aggregate of 11,838,582 shares of common stock, for a combined price of $2.01 per unit and (ii) 1,096,741 units, consisting of (a) pre-funded warrants to purchase 1,096,741 shares of the Company’s common stock and (b) associated common warrants to purchase 1,096,741 shares of common stock, for a combined price of $2.01 per unit. The pre-funded warrants had an exercise price of $0.01 per share and had no expiration. The common warrants are exercisable at an exercise price of $2.00 per share and expire five years from the date of issuance. The securities were sold pursuant to a securities purchase agreement entered into with accredited investors on March 28, 2019. The Company received aggregate gross proceeds from the private placement of approximately $26,000 before deducting placement agent fees and offering expenses of $2,175 and excluding the exercise of any warrants. The Company evaluated the terms of the common warrants issued and determined that they should be classified as equity instruments. The grant date fair value of the common warrants was estimated to be $1.78 per share, for a total of approximately $23,025. The Company estimated the fair value of the common warrants using a Black-Scholes model utilizing the following key valuation assumptions: the Company’s stock price, a risk free rate of 2.23%, an expected life of five years and an expected volatility of 76%. The Company evaluated the terms of the pre-funded warrants and classified them as equity. The pre-funded warrants were exercised in full in July 2019.

Stock-Based Awards

Stock-Based Awards	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Awards	9. Stock-Based Awards 2017 Stock Incentive Plan The Company’s 2017 Stock Incentive Plan (the “2017 Plan”) was approved by the Company’s stockholders on June 16, 2017 and became effective on June 28, 2017. Under the 2017 Plan, the Company may grant incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, awards of restricted stock units and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors are eligible to receive awards under the 2017 Plan; however, incentive stock options may only be granted to employees. The 2017 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board. The number of shares of common stock covered by options and the date those options become exercisable, type of options to be granted, exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted under the 2017 Plan with service-based vesting conditions generally vest over four years and may not have a duration in excess of ten years, although options have been granted with vesting terms of less than four years. The total number of shares of common stock that may be issued under the 2017 Plan was 5,380,802 as of September 30, 2020, of which 419,681 shares remained available for grant. Upon the adoption of the Plan, the Company initially reserved During the nine months ended September 30, 2020, pursuant to the terms of the 2017 Plan, the Company granted options to employees and directors to purchase 1,771,000 shares of common stock at a weighted average exercise price of $0.72 per share. Shares that are expired, terminated, surrendered or canceled without having been fully exercised will be available for future awards. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards. The exercise price for stock options granted may not be less than the fair market value of the common stock as of the date of grant. 2017 Employee Stock Purchase Plan On June 16, 2017, the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “2017 ESPP”), which became effective on June 28, 2017. A total of 150,000 shares of common stock were initially reserved for issuance under this plan. Under the 2017 ESPP, the number of shares of common stock that may be issued under the 2017 ESPP will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2018 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2027, equal to the least of (i) 622,408 shares, (ii) 1% of the outstanding shares of common stock on such date and (iii) an amount determined by the Company’s board of directors. The compensation committee of the board of directors has determined that the number of shares of common stock that may be issued under the 2017 ESPP would not be increased on January 1, 2019 or January 1, 2020. The Company has not issued any shares under the 2017 ESPP. 2016 Stock Incentive Plan The 2016 Plan provided for the Company to grant incentive stock options or nonqualified stock options, restricted stock, restricted stock units and other equity awards to employees, directors and consultants of the Company. The 2016 Plan was administered by the board of directors or, at the discretion of the board of directors, by a committee of the board. The exercise prices, vesting and other restrictions were determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted under the 2016 Plan with service-based vesting conditions vest over four years and expire after ten years. As of the effective date of the 2017 Plan, the board of directors determined to grant no further awards under the 2016 Plan. No stock options or other awards have been made under the 2016 Plan since the adoption of the 2017 Plan. Shares that are expired, terminated, surrendered or canceled without having been fully exercised will be available for future awards under the 2017 Plan. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards under the 2017 Plan. 2006 Stock Incentive Plan The 2006 Plan provided for the Company to grant incentive stock options or nonqualified stock options, restricted stock, restricted stock units and other equity awards to employees, directors and consultants of the Company. The 2006 Plan was administered by the board of directors or, at the discretion of the board of directors, by a committee of the board. The exercise prices, vesting and other restrictions were determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted under the 2006 Plan with service-based vesting conditions generally vest over four years and expire after ten years, although options have been granted with vesting terms of less than four years. The 2006 Plan expired in 2016. Since its expiration no further awards have been made under the 2006 Plan. Shares that are expired, terminated, surrendered or canceled without having been fully exercised will be available for future awards under the 2017 Plan. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards under the 2017 Plan. Stock Option Valuation The assumptions that the Company used to determine the grant-date fair value of the stock options granted to employees and directors during the nine months ended September 30, 2020 and 2019 were as follows, presented on a weighted average basis: Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 Risk-free interest rate 1.19 % 2.35 % Expected term (in years) 6.2 6.3 Expected volatility 76.0 % 76.0 % Expected dividend yield 0 % 0 % Stock Options The following table summarizes the Company’s stock option activity since January 1, 2020: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding at December 31, 2019 3,320,706 $ 3.87 7.4 $ — Granted 1,771,000 0.72 Exercised — 0.00 Canceled (450,018 ) 6.59 Forfeited (13,001 ) 2.54 Outstanding at September 30, 2020 4,628,687 $ 2.41 8.4 $ — Options exercisable at September 30, 2020 2,116,209 $ 3.46 7.7 $ — Options vested and expected to vest at September 30, 2020 4,542,745 $ 2.43 8.4 $ — Options exercisable at December 31, 2019 1,415,900 $ 5.56 5.2 $ — Options vested and expected to vest at December 31, 2019 3,264,851 $ 3.89 7.4 $ — The weighted average grant-date fair value of stock options granted during the nine months ended September 30, 2020 and 2019 was $0.48 and $1.11, respectively. The aggregate fair value of stock options that vested during the nine months ended September 30, 2020 and 2019 was $1,694 and $1,836, respectively. The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised during the nine months ended September 30, 2020 and 2019 was $0 and $109, respectively. Restricted Stock Units The following table summarizes the Company’s stock option activity since January 1, 2020: Weighted-Average Grant Date Units per Unit Outstanding, non-vested at December 31, 2019 50,000 $ 1.75 Issued — — Vested (50,000 ) $ 1.75 Canceled/forfeited — — Outstanding, non-vested at September 30, 2020 — $ 1.75 Stock-Based Compensation The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its statements of operations and comprehensive loss: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Research and development expenses $ 121 $ 177 $ 470 $ 370 General and administrative expenses 344 437 1,060 1,267 $ 465 $ 614 $ 1,530 $ 1,637 During the three months ended September 30, 2020 and 2019 the Company recognized stock-based compensation expense of $0 and $68, respectively, included in the table above, related to performance-based awards for which achievement of such performance-based conditions were deemed probable. During the nine months ended September 30, 2020 and 2019 the Company recognized stock-based compensation expense of $160 and $91, respectively, included in the table above, related to performance-based awards for which achievement of such performance-based conditions were deemed probable. As of September 30, 2020, the Company had an aggregate of $2,456 of unrecognized stock-based compensation expense, which it expects to recognize over a weighted average period of 2.8 years.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss per Share	10. Net Loss per Share Basic and diluted net loss per share was calculated as follows : Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net loss $ (5,023 ) $ (7,749 ) $ (16,161 ) $ (22,134 ) Denominator: Weighted average common shares outstanding—basic and diluted. 39,321,177 27,810,358 32,808,082 23,431,823 Total 39,321,177 27,810,358 32,808,082 23,431,823 Net loss per share —basic and diluted $ (0.13 ) $ (0.28 ) $ (0.49 ) $ (0.95 ) The Company’s potential dilutive securities, which include stock options and warrants, have been excluded from the computation of diluted net loss per share whenever the effect of including them would be to reduce the net loss per share. In periods where there is a net loss, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended September 30, 2020 2019 Warrants to purchase common stock 12,935,323 3,491,260 Stock options to purchase common stock 4,628,687 11,838,582 Restricted stock units to purchase common stock — 50,000 Total 17,564,010 15,379,842

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies Intellectual Property Licenses Harvard and Dana-Farber Agreement In August 2006, the Company entered into an exclusive license agreement with President and Fellows of Harvard College (“Harvard”) and Dana-Farber Cancer Institute (“DFCI”). The agreement granted the Company an exclusive worldwide license, with the right to sublicense, under specified patents and patent applications to develop, obtain regulatory approval for and commercialize specified product candidates based on cell-permeating peptides. Under the agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize one or more licensed products and to achieve specified milestone events by specified dates. In connection with entering into the agreement, the Company paid an upfront license fee and issued to Harvard and DFCI shares of its common stock. In February 2010, the agreement was amended and restated (the “Harvard/DFCI agreement”) under which additional patent rights were added to the scope of the license agreement and the annual license maintenance fees were increased. Under the Harvard/DFCI agreement, the Company is obligated to make aggregate milestones payments of up to $7,700 per licensed therapeutic product upon the Company’s achievement of specified clinical, regulatory and sales milestones with respect to such product and up to $700 per licensed diagnostic product upon the Company’s achievement of specified regulatory and sales milestones with respect to such product. In addition, the Company is obligated to pay royalties of low single-digit percentages on annual net sales of licensed products sold by the Company, its affiliates or its sublicensees. The royalties are payable on a product-by-product and country-by-country basis, and may be reduced in specified circumstances. In addition, the agreement obligates the Company to pay a percentage, up to the mid-twenties, of fees received by the Company in connection with its sublicense of the licensed products. In accordance with the terms of the agreement, the Company’s sublicense payment obligations may be subject to specified reductions. The Harvard/DFCI agreement requires the Company to pay annual license maintenance fees. Any payments made in connection with the annual license maintenance fees will be credited against any royalties due. The Company As of September 30, 2020, the Company had not developed a commercial product using the licensed technologies and no royalties under the agreement had been paid or were due. Under the Harvard/DFCI agreement, the Company is responsible for all patent expenses related to the prosecution and maintenance of the licensed patents and applications in-licensed under the agreement as well as cost reimbursement of amounts incurred for all documented patent-related expenses. The agreement will expire on a product-by-product and country-by-country basis upon the last to expire of any valid patent claim pertaining to licensed products covered under the agreement. Umicore Agreement In December 2006, the Company entered into a license agreement with Materia, Inc. (“Materia”), under which it was granted a non-exclusive worldwide license, with the right to sublicense, under specified patent and patent applications to utilize Materia’s catalysts to develop, obtain regulatory approval for and commercialize specified peptides owned or controlled by Materia and the right to manufacture specified compositions owned or controlled by Materia. In February 2017, Materia assigned the license agreement (the “Umicore agreement”) to Umicore Precious Metals Chemistry USA, LLC (“Umicore”), and Umicore agreed to continue to supply the Company under the agreement. Under the Umicore agreement, the Company is obligated to make aggregate milestone payments to Umicore of up to $6,400 upon the Company’s achievement of specified clinical, regulatory and sales milestones with respect to each licensed product. In addition, the Company is obligated to pay tiered royalties ranging in the low single-digit percentages on annual net sales of licensed products sold by the Company or its sublicensees. The royalties are payable on a product-by-product and country-by-country basis and may be reduced in specified circumstances. The Umicore agreement requires the Company to pay annual license fees of $50. The Company incurred license fees of $50 during the nine months ended September 30, 2020 and 2019. The Umicore agreement expires upon the expiration of the Company’s obligation to pay royalties in each territory covered under the agreement. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims that would have a material effect on its financial position, results of operations or cash flows, and it had not accrued any liabilities related to such obligations in its financial statements as of September 30, 2020 or December 31, 2019.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes The Company did not provide for any income taxes for the three and nine months ended September 30, 2020 and 2019. The Company has evaluated the positive and negative evidence bearing upon the realizability of its U.S. net deferred tax assets.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Event On November 11, 2020, the Company entered into a lease termination agreement with respect to its corporate headquarters at 490 Arsenal Way, Watertown, Massachusetts. The Company intends to relocate its corporate headquarters. The Company has migrated to a remote work environment and is evaluating its need for future office space. Between October 1, 2020 and November 11, 2020, the Company issued and sold an aggregate of 650,000 shares of its common stock to LPC pursuant to the Purchase Agreement, resulting in gross proceeds of $889. Between October 1, 2020 and October 5, 2020, the Company settled transactions that occurred pursuant to the Sales Agreement with JonesTrading, whereby the Company issued and sold an aggregate of 159,802 shares of its common stock, resulting in gross proceeds of $202.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of common stock and stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning the COVID-19 pandemic and the actions taken to contain or treat COVID-19, as well as the economic impact on local, regional, national and international markets. The Company has made estimates of the impact of COVID-19 within its financial statements and there may be changes to those estimates in future periods.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited condensed financial statements as of September 30, 2020 and for the nine months ended September 30, 2020 and 2019 have been prepared by the Company pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 that was filed with the SEC on March 30, 2020. The unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2020, the results of its operations for the three and nine months ended September 30, 2020 and 2019 and its cash flows for the nine months ended September 30, 2020 and 2019. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2020 and 2019 are unaudited. The results for the nine months ended September 30, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2019 has been derived from the Company’s audited financial statements for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 30, 2020.
Cash Equivalents	Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market accounts, corporate notes and commercial paper, are stated at fair value.
Restricted Cash	Restricted Cash As of September 30, 2020 and December 31, 2019, current restricted cash consisted of $25 of cash deposited in a separate restricted bank account as a security deposit for the Company’s corporate credit cards. As of September 30, 2020 and December 31, 2019, non-current restricted cash consisted of $568 of cash deposited in a separate restricted bank account as a security deposit for
Investments	Investments The Company classifies its available-for-sale debt security investments as current assets on the balance sheet if they mature within one year from the balance sheet date. The Company classifies its investments as available-for-sale securities. The Company’s investments are measured and reported at fair value using quoted prices in active markets for similar securities or using other inputs that are observable or can be corroborated by observable market data. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit). The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the statements of operations and comprehensive loss. The Company evaluates its investments with unrealized losses for other-than-temporary impairment. When assessing investments for other-than-temporary declines in value, the Company considers such factors as, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general, among other factors. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable. • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts payable and accrued expenses approximate their fair value due to the short-term nature of these liabilities.
Net Loss per Share	Net Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) is computed by adjusting income (loss) per share to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of shares of common stock outstanding for the period, including potential dilutive common shares. For purpose of this calculation, outstanding options, restricted stock units and warrants to purchase common stock are considered potential dilutive common shares. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.
Risks and Uncertainties	Risks and Uncertainties In December 2019, an outbreak of respiratory illness caused by a strain of novel coronavirus, COVID-19, began in China. That outbreak has led to numerous confirmed cases worldwide, including in the United States and other countries where the Company is conducting clinical trials or activities in support thereof. The World Health Organization declared the outbreak a global pandemic on March 11, 2020. The impact of this pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. Potential impacts to the Company’s the Company’s the Company believes its the Company’s its the Company has the Company’s Any negative impact that the COVID-19 outbreak has on the ability of the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s the Company’s
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Fair Value of Financial Instruments In This ASU removes the requirement to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy; the policy for timing of transfers between levels; and the valuation processes for Level 3 fair value measurements
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates

Fair Value of Financial Assets

Fair Value of Financial Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Summary of Assets Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of September 30, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 3,362 $ — $ — $ 3,362 Government sponsored enterprises — 500 — 500 Corporate notes — 1,000 — 1,000 Commercial paper — 1,500 — 1,500 Investments: Treasury bills — 2,749 — 2,749 Agency bonds — 3,522 — 3,522 $ 3,362 $ 9,271 $ — $ 12,633 Fair Value Measurements as of December 31, 2019 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 4,208 $ — $ — $ 4,208 Investments: Corporate notes — 5,491 — 5,491 Commercial paper — 7,476 — 7,476 $ 4,208 $ 12,967 $ — $ 17,175

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Summary of Fair Value of Available for Sale Investments	As of September 30, 2020 and December 31, 2019, the fair value of available-for-sale investments by type of security was as follows: September 30, 2020 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Agency bonds $ 3,522 $ — $ — $ 3,522 Treasury bills 2,749 — — 2,749 $ 6,271 $ — $ — $ 6,271 December 31, 2019 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Corporate notes $ 5,489 $ 2 $ — $ 5,491 Commercial paper 7,470 6 — 7,476 $ 12,959 $ 8 $ — $ 12,967

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following: September 30, 2020 December 31, 2019 Laboratory equipment $ 406 $ 451 Computer equipment and software 181 177 Furniture and fixtures 189 189 776 817 Less: Accumulated depreciation and amortization (629 ) (522 ) $ 147 $ 295

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: September 30, 2020 December 31, 2019 External research and development services $ 1,973 $ 1,673 Payroll and payroll-related costs 945 1,281 Professional fees 490 635 Other 279 352 $ 3,687 $ 3,941

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Valuation Assumptions of Stock Options Granted	The assumptions that the Company used to determine the grant-date fair value of the stock options granted to employees and directors during the nine months ended September 30, 2020 and 2019 were as follows, presented on a weighted average basis: Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 Risk-free interest rate 1.19 % 2.35 % Expected term (in years) 6.2 6.3 Expected volatility 76.0 % 76.0 % Expected dividend yield 0 % 0 %
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity since January 1, 2020: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding at December 31, 2019 3,320,706 $ 3.87 7.4 $ — Granted 1,771,000 0.72 Exercised — 0.00 Canceled (450,018 ) 6.59 Forfeited (13,001 ) 2.54 Outstanding at September 30, 2020 4,628,687 $ 2.41 8.4 $ — Options exercisable at September 30, 2020 2,116,209 $ 3.46 7.7 $ — Options vested and expected to vest at September 30, 2020 4,542,745 $ 2.43 8.4 $ — Options exercisable at December 31, 2019 1,415,900 $ 5.56 5.2 $ — Options vested and expected to vest at December 31, 2019 3,264,851 $ 3.89 7.4 $ —
Summary of Restricted Stock Unit Activity	The following table summarizes the Company’s stock option activity since January 1, 2020: Weighted-Average Grant Date Units per Unit Outstanding, non-vested at December 31, 2019 50,000 $ 1.75 Issued — — Vested (50,000 ) $ 1.75 Canceled/forfeited — — Outstanding, non-vested at September 30, 2020 — $ 1.75
Summary of Stock Based Compensation Expense	The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its statements of operations and comprehensive loss: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Research and development expenses $ 121 $ 177 $ 470 $ 370 General and administrative expenses 344 437 1,060 1,267 $ 465 $ 614 $ 1,530 $ 1,637

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Basic and Diluted Net Loss per Share	Basic and diluted net loss per share was calculated as follows : Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net loss $ (5,023 ) $ (7,749 ) $ (16,161 ) $ (22,134 ) Denominator: Weighted average common shares outstanding—basic and diluted. 39,321,177 27,810,358 32,808,082 23,431,823 Total 39,321,177 27,810,358 32,808,082 23,431,823 Net loss per share —basic and diluted $ (0.13 ) $ (0.28 ) $ (0.49 ) $ (0.95 )
Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share	The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended September 30, 2020 2019 Warrants to purchase common stock 12,935,323 3,491,260 Stock options to purchase common stock 4,628,687 11,838,582 Restricted stock units to purchase common stock — 50,000 Total 17,564,010 15,379,842

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 21, 2020	Apr. 02, 2019	Jun. 30, 2020	Jul. 31, 2019	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued					$ 364	$ 10,729
Discounts, commissions and offering expenses					159	$ 1,186	$ 37
Cash, cash equivalents and investments					14,121			$ 14,121
Accumulated deficit					(214,296)			(214,296)	$ (198,135)
Underwritten Public Offering [Member]
Class of Stock [Line Items]
Shares issued, price per share			$ 1.10			$ 1.10
Stock issued during period, shares			10,162,059
Additional shares of common stock issued upon partial exercise of option			1,071,149
Gross proceeds from issuance of common stock			$ 11,178
Discounts, commissions and offering expenses			$ 932
Private Placement [Member]
Class of Stock [Line Items]
Discounts, commissions and offering expenses		$ 2,175
Aggregate gross proceeds from private placement		$ 26,000
Common Stock [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued					$ 1	$ 11
Stock issued during period, shares					606,747	11,425,118
Common Stock [Member] | Private Placement [Member]
Class of Stock [Line Items]
Outstanding pre-funded warrants exercised				1,096,741
Common Stock [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Stock repurchase program, number of shares to be purchased		11,838,582
Common Stock [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Stock repurchase program, number of shares to be purchased		1,096,741
Stock Units [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Shares issued, price per share		$ 2.01
Aggregate number of common stock shares issued and sold		11,838,582
Stock Units [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Shares issued, price per share		$ 2.01
Aggregate number of common stock shares issued and sold		1,096,741
Common Warrants [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Aggregate shares purchase for warrants		11,838,582
Warrants exercisable, exercise price		$ 2
Warrants and rights outstanding, term		5 years
Pre-funded Warrants [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Aggregate shares purchase for warrants		1,096,741
Warrants exercisable, exercise price		$ 0.01
Purchase Agreement [Member] | LPC [Member] | Common Stock [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued	$ 500
Shares issued, price per share	$ 1.36
Additional shares of common stock issued	367,647
Period of common stock shares sold	36 months
Commencement period of common stock shares sold	2020-10
Purchase Agreement [Member] | LPC [Member] | Maximum [Member] | Common Stock [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued	$ 15,000
Additional number of common stock shares sold	14,500
Sales Agreement [Member] | JonesTrading [Member]
Class of Stock [Line Items]
Discounts, commissions and offering expenses								$ 24
Aggregate number of common stock shares issued and sold								1,281,571
Gross proceeds from common stock shares issued and sold								$ 785
Sales Agreement [Member] | JonesTrading [Member] | Maximum [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued				$ 15,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, current	$ 25	$ 25
Restricted cash, non-current	$ 568	568
ASU 2018-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
Security Deposit Related to Credit Card Accounts [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, current	$ 25	25
Security Deposit Related to Lease Facility [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, non-current	$ 568	$ 568

Fair Value of Financial Asset_2

Fair Value of Financial Assets - Summary of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	$ 6,271	$ 12,967
Agency Bonds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	3,522
Treasury Bills [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	2,749
Corporate Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		5,491
Commercial Paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		7,476
Recurring [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	12,633	17,175
Recurring [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	3,362	4,208
Recurring [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	9,271	12,967
Recurring [Member] | Agency Bonds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	3,522
Recurring [Member] | Agency Bonds [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	3,522
Recurring [Member] | Treasury Bills [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	2,749
Recurring [Member] | Treasury Bills [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	2,749
Recurring [Member] | Corporate Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		5,491
Recurring [Member] | Corporate Notes [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		5,491
Recurring [Member] | Commercial Paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		7,476
Recurring [Member] | Commercial Paper [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		7,476
Recurring [Member] | Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	3,362	4,208
Recurring [Member] | Money Market Funds [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	3,362	$ 4,208
Recurring [Member] | Government Sponsored Enterprises [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	500
Recurring [Member] | Government Sponsored Enterprises [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	500
Recurring [Member] | Corporate Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	1,000
Recurring [Member] | Corporate Notes [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	1,000
Recurring [Member] | Commercial Paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	1,500
Recurring [Member] | Commercial Paper [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments	$ 1,500

Fair Value of Financial Asset_3

Fair Value of Financial Assets - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Available-for-sale investments, maximum contractual maturity period	1 year
Fair value, assets transfers from Level 1 to Level 2	$ 0	$ 0
Fair value, assets transfers from Level 2 to Level 1	0	0
Fair Value, assets transfers into (out of) Level 3	$ 0	$ 0

Investments - Summary of Fair V

Investments - Summary of Fair Value of Available for Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	$ 6,271	$ 12,959
Investments, Gross Unrealized Gain		8
Investments, Fair Value	6,271	12,967
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	3,522
Investments, Fair Value	3,522
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	2,749
Investments, Fair Value	$ 2,749
Corporate Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost		5,489
Investments, Gross Unrealized Gain		2
Investments, Fair Value		5,491
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost		7,470
Investments, Gross Unrealized Gain		6
Investments, Fair Value		$ 7,476

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 776	$ 817
Less: Accumulated depreciation and amortization	(629)	(522)
Property, plant and equipment, net	147	295
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	406	451
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	181	177
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 189	$ 189

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 153,000
Proceeds from property and equipment	66,000
Gain (loss) on disposal of property and equipment	66,000
Accumulated depreciation	629,000	$ 522,000
Fully Depreciated Assets [Member]
Property Plant And Equipment [Line Items]
Disposal of property and equipment	45,000	723,000
Proceeds from property and equipment	66,000	0
Gain (loss) on disposal of property and equipment	$ 66,000
Not Fully Depreciated Assets [Member]
Property Plant And Equipment [Line Items]
Disposal of property and equipment		26,000
Proceeds from property and equipment		0
Gain (loss) on disposal of property and equipment		(5,000)
Accumulated depreciation		$ 21,000

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
External research and development services	$ 1,973	$ 1,673
Payroll and payroll-related costs	945	1,281
Professional fees	490	635
Other	279	352
Total accrued expenses and other current liabilities	$ 3,687	$ 3,941

Paycheck Protection Loan - Addi

Paycheck Protection Loan - Additional Information (Detail) - Paycheck Protection Program CARES Act [Member] $ in Thousands	Apr. 30, 2020USD ($)	Sep. 30, 2020
Debt Instrument [Line Items]
Proceeds from loan	$ 384
Number of times for loans to qualifying businesses average monthly payroll costs	2.5
Term of unforgiven portion of loan	2 years
Interest rate	1.00%
Term of deferral payments	6 months
Debt instrument, description		The PPP, established as part of the Coronavirus Aid, Relief and Economic Security Act (“CARES Act”), provides for loans to qualifying businesses for amounts up to 2.5 times of the average monthly payroll expenses of the qualifying business. The loan and accrued interest are forgivable after eight weeks if the borrower uses the loan proceeds for eligible purposes, including payroll, benefits, rent and utilities. The amount of loan forgiveness may be reduced if the borrower terminates employees or reduces salaries during the eight-week period. The unforgiven portion of the PPP loan is payable over two years at an interest rate of 1%, with a deferral of payments for the first six months. The Company used the proceeds for purposes consistent with the PPP.
Minimum [Member]
Debt Instrument [Line Items]
Term of loan and accrued interest forgivable	56 days

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands	Sep. 21, 2020USD ($)$ / sharesshares	Apr. 02, 2019USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares	Jul. 31, 2019USD ($)	Sep. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)$ / sharesshares
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued					$ 364	$ 10,729
Discounts, commissions and offering expenses					$ 159	$ 1,186	$ 37
Grant date fair value of the common warrants, per share | $ / shares					$ 1.78			$ 1.78
Grant date fair value of the common warrants								$ 23,025
Risk Free Rate [Member]
Class of Stock [Line Items]
Warrants and rights, measurement input					0.0223			0.0223
Expected Term [Member]
Class of Stock [Line Items]
Warrants and rights outstanding, term					5 years			5 years
Volatility [Member]
Class of Stock [Line Items]
Warrants and rights, measurement input					0.76			0.76
Underwritten Public Offering [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares			$ 1.10			$ 1.10
Stock issued during period, shares | shares			10,162,059
Additional shares of common stock issued upon partial exercise of option | shares			1,071,149
Gross proceeds from issuance of common stock			$ 11,178
Discounts, commissions and offering expenses			$ 932
Private Placement [Member]
Class of Stock [Line Items]
Discounts, commissions and offering expenses		$ 2,175
Aggregate gross proceeds from private placement		$ 26,000
Sales Agreement [Member] | JonesTrading [Member]
Class of Stock [Line Items]
Discounts, commissions and offering expenses								$ 24
Aggregate number of common stock shares issued and sold | shares								1,281,571
Gross proceeds from common stock shares issued and sold								$ 785
Sales Agreement [Member] | JonesTrading [Member] | Maximum [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued				$ 15,000
Common Stock [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued					$ 1	$ 11
Stock issued during period, shares | shares					606,747	11,425,118
Common Stock [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Stock repurchase program, number of shares to be purchased | shares		11,838,582
Common Stock [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Stock repurchase program, number of shares to be purchased | shares		1,096,741
Common Stock [Member] | Purchase Agreement [Member] | LPC [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued	$ 500
Shares issued, price per share | $ / shares	$ 1.36
Additional shares of common stock issued | shares	367,647
Period of common stock shares sold	36 months
Commencement period of common stock shares sold	2020-10
Common Stock [Member] | Purchase Agreement [Member] | LPC [Member] | Maximum [Member]
Class of Stock [Line Items]
Aggregate offering price of common stock shares issued	$ 15,000
Additional number of common stock shares sold | shares	14,500
Stock Units [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares		$ 2.01
Aggregate number of common stock shares issued and sold | shares		11,838,582
Stock Units [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares		$ 2.01
Aggregate number of common stock shares issued and sold | shares		1,096,741
Common Warrants [Member] | Private Placement [Member] | Purchase Agreement One [Member]
Class of Stock [Line Items]
Aggregate shares purchase for warrants | shares		11,838,582
Warrants exercisable, exercise price | $ / shares		$ 2
Warrants and rights outstanding, term		5 years
Pre-funded Warrants [Member] | Private Placement [Member] | Purchase Agreement Two [Member]
Class of Stock [Line Items]
Aggregate shares purchase for warrants | shares		1,096,741
Warrants exercisable, exercise price | $ / shares		$ 0.01

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2020	Jan. 01, 2019	Jun. 16, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted						1,771,000
Options granted, weighted average exercise price per share						$ 0.72
Weighted average grant-date fair value of stock options						$ 0.48	$ 1.11
Aggregate fair value of stock options vested						$ 1,694	$ 1,836
Aggregate intrinsic value of stock options exercised						0	109
Recognized stock-based compensation expense				$ 465	$ 614	1,530	1,637
Aggregate unrecognized stock-based compensation expense				2,456		$ 2,456
Unrecognized stock-based compensation expense, weighted average period expects for recognition						2 years 9 months 18 days
Performance-based Awards [[Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense				$ 0	$ 68	$ 160	$ 91
2017 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted vesting period						4 years
Number of shares, available for grant				5,380,802		5,380,802
Number of shares remained available for grant				419,681		419,681
Stock reserved for future issuance				1,244,816		1,244,816
Maximum annual increase in common stock reserved for future issuance						1,244,816
Percentage of common stock shares outstanding						4.00%
Increase to shares authorized for issuance	1,112,414	589,939
Options granted						1,771,000
Options granted, weighted average exercise price per share						$ 0.72
2016 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted vesting period						4 years
Stock option expiration period						10 years
Number of shares, available for grant				0		0
2016 Stock Incentive Plan [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for future issuance				424,601		424,601
2017 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, available for grant				0		0
Stock reserved for future issuance			150,000
Maximum annual increase in common stock reserved for future issuance			622,408
Percentage of common stock shares outstanding			1.00%
Increase to shares authorized for issuance	0	0
Stock incentive plan description						On June 16, 2017, the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “2017 ESPP”), which became effective on June 28, 2017. A total of 150,000 shares of common stock were initially reserved for issuance under this plan. Under the 2017 ESPP, the number of shares of common stock that may be issued under the 2017 ESPP will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2018 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2027, equal to the least of (i) 622,408 shares, (ii) 1% of the outstanding shares of common stock on such date and (iii) an amount determined by the Company’s board of directors. The compensation committee of the board of directors has determined that the number of shares of common stock that may be issued under the 2017 ESPP would not be increased on January 1, 2019 or January 1, 2020. The Company has not issued any shares under the 2017 ESPP.
2006 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted vesting period						4 years
Stock option expiration period						10 years
Number of shares, available for grant				0		0
Stock incentive plan termination year						2016
Maximum [Member] | 2017 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted vesting period						4 years
Stock option expiration period						10 years
Maximum [Member] | 2006 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted vesting period						4 years

Stock-Based Awards - Valuation

Stock-Based Awards - Valuation Assumptions of Stock Options Granted (Detail)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.19%	2.35%
Expected term (in years)	6 years 2 months 12 days	6 years 3 months 18 days
Expected volatility	76.00%	76.00%
Expected dividend yield	0.00%	0.00%

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Activity (Detail) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance	3,320,706
Number of Shares, Granted	1,771,000
Number of Shares, Canceled	(450,018)
Number of Shares, Forfeited	(13,001)
Number of Shares, Ending balance	4,628,687	3,320,706
Number of Shares, Options exercisable	2,116,209	1,415,900
Number of Shares, Options vested and expected to vest	4,542,745	3,264,851
Weighted Average Exercise Price, Beginning balance	$ 3.87
Weighted Average Exercise Price, Granted	0.72
Weighted Average Exercise Price, Exercised	0
Weighted Average Exercise Price,Canceled	6.59
Weighted Average Exercise Price, Forfeited	2.54
Weighted Average Exercise Price, Ending balance	2.41	$ 3.87
Weighted Average Exercise Price, Options exercisable	3.46	5.56
Weighted Average Exercise Price, Options vested and expected to vest	$ 2.43	$ 3.89
Weighted-Average Remaining Contractual Term, Outstanding	8 years 4 months 24 days	7 years 4 months 24 days
Weighted Average Remaining Contractual Term, Options exercisable	7 years 8 months 12 days	5 years 2 months 12 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	8 years 4 months 24 days	7 years 4 months 24 days

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Detail) - 2017 Stock Incentive Plan [Member] - Restricted Stock Units [Member]	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Units
Beginning balance | shares	50,000
Vested | shares	(50,000)
Weighted-Average Grant Date per Unit
Beginning balance	$ 1.75
Vested	1.75
Ending balance	$ 1.75

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 465	$ 614	$ 1,530	$ 1,637
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	121	177	470	370
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 344	$ 437	$ 1,060	$ 1,267

Net Loss per Share - Basic and

Net Loss per Share - Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (5,023)	$ (4,390)	$ (6,748)	$ (7,749)	$ (7,172)	$ (7,213)	$ (16,161)	$ (22,134)
Denominator:
Weighted average common shares outstanding—basic and diluted.	39,321,177			27,810,358			32,808,082	23,431,823
Total	39,321,177			27,810,358			32,808,082	23,431,823
Net loss per share —basic and diluted	$ (0.13)			$ (0.28)			$ (0.49)	$ (0.95)

Net Loss per Share - Summary of

Net Loss per Share - Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	17,564,010	15,379,842
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	4,628,687	11,838,582
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	12,935,323	3,491,260
Restricted Stock Units to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share		50,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)Milestone	Sep. 30, 2019USD ($)	Feb. 28, 2010USD ($)	Dec. 31, 2006USD ($)
Harvard and Dana-Farber Agreement [Member]
Other Commitments [Line Items]
Milestone payments	$ 0	$ 0	$ 0	$ 0
Additional milestones achieved | Milestone			0
Additional liabilities for milestone payments	0		$ 0
Payments for royalties			0
Harvard and Dana-Farber Agreement [Member] | Therapeutic Product [Member]
Other Commitments [Line Items]
Aggregate milestones payments					$ 7,700,000
Harvard and Dana-Farber Agreement [Member] | Diagnostic Product [Member]
Other Commitments [Line Items]
Aggregate milestones payments					$ 700,000
Harvard and Dana-Farber Agreement [Member] | License [Member]
Other Commitments [Line Items]
Annual license maintenance fees			145,000	145,000
Umicore Agreement [Member]
Other Commitments [Line Items]
Aggregate milestones payments						$ 6,400,000
Milestone payments	0	$ 0	$ 0	0
Additional milestones achieved | Milestone			0
Additional liabilities for milestone payments	$ 0		$ 0
Umicore Agreement [Member] | License [Member]
Other Commitments [Line Items]
Annual license maintenance fees			50,000	$ 50,000
Umicore Agreement [Member] | License and Maintenance [Member]
Other Commitments [Line Items]
Annual license maintenance fees			$ 50,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income taxes	$ 0	$ 0	$ 0	$ 0

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ in Thousands	Oct. 05, 2020	Nov. 11, 2020	Sep. 30, 2020
Purchase Agreement [Member] | LPC [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Aggregate number of common stock shares issued and sold		650,000
Gross proceeds from common stock shares issued and sold		$ 889
Sales Agreement [Member] | JonesTrading [Member]
Subsequent Event [Line Items]
Aggregate number of common stock shares issued and sold			1,281,571
Gross proceeds from common stock shares issued and sold			$ 785
Sales Agreement [Member] | JonesTrading [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Aggregate number of common stock shares issued and sold	159,802
Gross proceeds from common stock shares issued and sold	$ 202