Evelo Biosciences (EVLO) 10-Q 12 May 22 2022 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2022	May 09, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-38473
Entity Registrant Name	Evelo Biosciences, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5594527
Entity Address, Address Line One	620 Memorial Drive
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	(617)
Local Phone Number	577-0300
Title of 12(b) Security	Common Stock,$0.001 par value per share
Trading Symbol	EVLO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		53,659,859
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001694665
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 39,631	$ 68,441
Prepaid expenses and other current assets	3,494	2,585
Total current assets	43,125	71,026
Property and equipment, net	6,126	6,622
Right of use asset - operating lease	8,419	8,910
Other assets	1,155	1,313
Total assets	58,825	87,871
Current liabilities:
Debt, current portion	1,844	0
Accounts payable	1,760	1,601
Accrued expenses	9,876	13,068
Operating lease liability, current portion	2,027	1,951
Other current liabilities	665	742
Total current liabilities	16,172	17,362
Noncurrent liabilities:
Total debt	44,772	46,557
Operating lease liability, net of current portion	7,183	7,785
Deferred revenue	7,500	7,500
Total liabilities	75,627	79,204
Commitments and contingencies (Note 10)
Stockholder’s (deficit) equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued or outstanding as of March 31, 2022 and December 31, 2021, respectively	0	0
#REF!	54	54
Additional paid-in capital	427,700	423,308
Accumulated deficit	(444,556)	(414,695)
Total stockholders’ (deficit) equity	(16,802)	8,667
Total liabilities and stockholders’ (deficit) equity	$ 58,825	$ 87,871

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	53,648,189	53,576,454
Common stock, shares outstanding (in shares)	53,648,189	53,576,454

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 19,321	$ 21,508
General and administrative	9,417	5,963
Total operating expenses	28,738	27,471
Loss from operations	(28,738)	(27,471)
Other (expense) income:
Interest expense, net	(1,027)	(765)
Other miscellaneous income, net	20	162
Total other expense, net	(1,007)	(603)
Loss before income taxes	(29,745)	(28,074)
Income tax expense	(116)	(122)
Net loss	$ (29,861)	$ (28,196)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.56)	$ (0.55)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.56)	$ (0.55)
Weighted-average number of common shares outstanding, basic (in shares)	53,619,635	51,343,923
Weighted-average number of common shares outstanding, diluted (in shares)	53,619,635	51,343,923

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders’ (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		47,470,119
Beginning balance at Dec. 31, 2020	$ 30,485	$ 47	$ 322,957	$ (292,519)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net (in shares)		5,814,734
Issuance of common stock, net	81,961	$ 6	81,955
Issuance of common stock under Employee Stock Purchase Plan (in shares)		27,587
Issuance of common stock under Employee Stock Purchase Plan	90		90
Exercise of stock options (in shares)		45,299
Exercise of stock options	235	$ 0	235
Stock-based compensation expense	3,264		3,264
Net loss	(28,196)			(28,196)
Ending balance (in shares) at Mar. 31, 2021		53,357,739
Ending balance at Mar. 31, 2021	87,839	$ 53	408,501	(320,715)
Beginning balance (in shares) at Dec. 31, 2021		53,576,454
Beginning balance at Dec. 31, 2021	8,667	$ 54	423,308	(414,695)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under Employee Stock Purchase Plan (in shares)		36,329
Issuance of common stock under Employee Stock Purchase Plan	129		129
Vesting of restricted common stock (in shares)		35,406
Vesting of restricted common stock	$ 0
Exercise of stock options (in shares)	0
Stock-based compensation expense	$ 4,275		4,275
Fees associated with public offering of common stock	(12)		(12)
Net loss	(29,861)			(29,861)
Ending balance (in shares) at Mar. 31, 2022		53,648,189
Ending balance at Mar. 31, 2022	$ (16,802)	$ 54	$ 427,700	$ (444,556)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net loss	$ (29,861)	$ (28,196)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	4,275	3,264
Depreciation expense	517	536
Non-cash interest expense	59	124
Non-cash lease expense	491	445
Loss on disposal of property and equipment	232	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,011)	46
Accounts receivable	0	(7,500)
Accounts payable	159	(1,062)
Accrued expenses and other current liabilities	(3,267)	(981)
Operating lease liabilities	(526)	(458)
Deferred revenue	0	7,500
Other liabilities	0	2
Net cash used in operating activities	(28,932)	(26,280)
Investing activities
Purchases of property and equipment	(153)	(314)
Net cash used in investing activities	(153)	(314)
Financing activities
Proceeds from issuance of common stock, net of issuance cost	0	82,003
Proceeds from the issuance of common stock under employee stock purchase plan and exercise of stock options	129	325
Fees associated with public offering of common stock	(12)	0
Net cash provided by financing activities	117	82,328
Net (decrease) increase in cash, cash equivalents and restricted cash	(28,968)	55,734
Cash, cash equivalents and restricted cash – beginning of period	69,754	70,420
Cash, cash equivalents and restricted cash – end of period	40,786	126,154
Supplemental disclosure of cash flow information
Cash paid for interest	973	649
Cash paid for taxes	393	0
Noncash investing and financing activities
Public offering costs in accrued expenses	0	42
Property and equipment additions included in accrued expenses	$ 27	$ 171

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Evelo Biosciences, Inc. ("Evelo," "we," "our," "us" or the "Company”) is a biotechnology company incorporated in Delaware on May 6, 2014. We are discovering and developing a new class of orally delivered investigational medicines that are intended to act on cells in the small intestine to produce therapeutic effects throughout the body. We are advancing these investigational medicines with the aim of treating a broad range of immune mediated diseases, with an initial focus on inflammatory diseases and oncology. Our headquarters is located in Cambridge, Massachusetts. Since inception, we have devoted substantially all of our efforts to research and development and raising capital. We have not generated any product or license revenue related to our primary business purpose to date. We are subject to a number of risks similar to those of other development stage companies, including a dependence on key individuals, the need to develop commercially viable products, the competition from other companies, many of whom are larger and better capitalized, and the need to obtain adequate additional financing to fund the development of our products. We have incurred operating losses since inception and we expect such losses and negative operating cash flows to continue for the foreseeable future. As of March 31, 2022, we held cash, cash equivalents and restricted cash of $40.8 million and have an accumulated deficit of $444.6 million. Since inception, we have financed operations primarily with the proceeds from the issuance of common stock combined with proceeds from previous sales of convertible preferred stock to equity investors, and from debt financing. In accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) , we evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date that these unaudited condensed consolidated financial statements are issued. The transition to profitability is dependent upon the successful development, approval and commercialization of our products and product candidates, and the achievement of a level of revenues adequate to support our cost structure. Based on our current operating plan, we believe that our cash and cash equivalents balance as of March 31, 2022 will not be sufficient to fund operations and capital expenditures for at least the twelve months following the filing of this Quarterly Report on Form 10-Q, and we will need to obtain additional funding. We intend to pursue strategic partnerships and collaborations, or obtain additional funding through available financing sources which include additional public offerings of common stock and the private financing of debt or equity. Management’s belief with respect to our ability to fund operations is based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, we may need to seek additional funding sooner than would otherwise be expected. There can be no assurance that we will be able to obtain additional funding on acceptable terms, if at all. If we are unable to obtain sufficient funding, we may be required to delay our development efforts, limit activities and reduce research and development costs, which could adversely affect our business prospects. Because of the uncertainty in securing additional funding and the insufficient amount of cash and cash equivalent resources as of March 31, 2022, management concluded that substantial doubt exists with respect to our ability to continue as a going concern within one year after the date that these unaudited condensed consolidated financial statements are issued. The accompanying unaudited condensed consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standard Codification (“ASC”) and ASUs of the FASB. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP were condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2021 and the related notes thereto. These unaudited condensed consolidated financial statements are prepared on the same basis as the audited financial statements. In the opinion of our management, the accompanying unaudited condensed consolidated financial statements contain all adjustments which are necessary to present fairly our financial position as of March 31, 2022, the results of our operations and stockholders' equity for the three months ended March 31, 2022 and 2021. Such adjustments are of a normal and recurring nature. The results for the three months ended March 31, 2022 are not necessarily indicative of the results for the year ending December 31, 2022, or for any future period.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to, estimates related to the application of Revenue from Contracts with Customers (Topic 606) ("ASC 606") to our collaboration agreement with Meddist Company Limited (" ALJ"), the accrual of research and development expenses, the expected future lives of property and equipment and the valuation of stock-based awards. We base our estimates on historical experience and market-specific or other relevant assumptions that we believe to be reasonable under the circumstances. Actual results could differ from those estimates. Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of our business and our wholly owned and controlled subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Subsequent Event Considerations We consider events or transactions that occur after the balance sheet date but prior to the issuance of the unaudited condensed consolidated financial statements to identify matters that require additional disclosure or that may significantly affect currently reported financial condition such as our judgments related to estimates. Subsequent events were evaluated as required. Those events determined to be sufficiently material are described in Note 17 - Subsequent Events. Emerging Growth Company Status We are an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"), and we may take advantage of reduced reporting requirements that are otherwise applicable to public companies until we are no longer an emerging growth company. Section 107 of the JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. We elected to use the extended transition period for complying with new or revised accounting standards and, as a result of this election, our unaudited condensed consolidated financial statements may not be comparable to companies that comply with public company effective dates. We may take advantage of these exemptions up until the last day of the fiscal year following the fifth anniversary of our IPO or such earlier time that we no longer are an emerging growth company. We would cease to be an emerging growth company if we have more than $1.07 billion in annual revenue, have more than $700.0 million in market value of our stock held by non-affiliates (and have been a public company for at least 12 months and have filed one annual report on Form 10-K), or have issued more than $1.0 billion of non-convertible debt securities over a three-year period. Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially expose us to concentrations of credit risk primarily consist of cash and cash equivalents. We place our cash and cash equivalents primarily in two custodian accounts at accredited financial institutions. Such deposits have and will continue to exceed federally insured limits. As of March 31, 2022 and December 31, 2021, we have no off-balance sheet risk such as foreign exchange contracts, option contracts, derivatives or other foreign hedging arrangements. Comprehensive Loss Comprehensive loss consists of net loss and changes in equity during a period arising from transactions and other equity and circumstances, of which we have none. Our comprehensive loss equals our net loss for all periods presented. Cash, Cash Equivalents and Restricted Cash Cash equivalents are comprised of highly liquid investments that are readily convertible into cash with original maturities of three months or less, comprised of cash held in banks and amounts held in money market funds. Cash equivalents are stated at cost, which approximates market value. Our restricted cash consists of restricted cash in connection with building leases for our office and laboratory premises and deposits held in relation to our credit card facility. As of March 31, 2022 and December 31, 2021 we had $1.2 million and $1.3 million, respectively, in noncurrent restricted cash included within other assets in the unaudited condensed consolidated balance sheets. The following reconciles cash, cash equivalents and restricted cash as of March 31, 2022 and December 31, 2021, as presented on our statements of cash flows to the related balance sheet accounts (in thousands): March 31, 2022 December 31, 2021 Cash and cash equivalents: Cash $ 5,224 $ 1,452 Money market funds 34,407 66,989 Total cash and cash equivalents 39,631 68,441 Restricted cash 1,155 1,313 Cash, cash equivalents and restricted cash $ 40,786 $ 69,754 Fair Value of Financial Instruments FASB ASC 820, Fair Value Measurement (“ASC 820”) establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and our own assumptions (unobservable inputs). As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and • Level 3 inputs are unobservable inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment we exercised in determining fair value is greatest for instruments categorized in Level 3. Property and Equipment Property and equipment consists of computer hardware and software, furniture and fixtures, office equipment, research and lab equipment and leasehold improvement recorded at cost. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets. A summary of the estimated useful lives of our property and equipment is as follows: Computer hardware 3 to 5 years Computer software 3 years Furniture and fixtures 7 years Research and laboratory equipment (used/new) 3 to 5 years Leasehold improvements Lesser of asset life or remaining life of lease Assets acquired and not placed in service are recorded to construction-in-process and are not depreciated. Assets are recorded according to classification and depreciated upon placement in service. Repairs and maintenance costs are expensed as incurred. We periodically evaluate property and equipment for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. We neither identified nor recorded any material impairment charges during the periods presented. Income Taxes We record deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. We account for interest and penalties related to uncertain tax positions as part of our provision for income taxes. A valuation allowance is provided to reduce the net deferred tax assets to the amount that will more likely than not be realized. We have incurred net losses since inception and, in recognition of the uncertainty in the realization of favorable tax attributes in future tax returns, we recorded a full valuation allowance against our otherwise recognizable net deferred tax assets. Revenue Recognition We recognize revenue under the Financial Accounting Standards Board guidance of ASC 606. Since inception, we have entered into one contract subject to ASC 606, however, as discussed in Note 3 - ALJ Commercialization and License Agreement, all revenue pursuant to this arrangement has been deferred. Collaboration Agreements We analyze our collaboration arrangements under the Financial Accounting Standards Board guidance of Collaborative Arrangements (Topic 808) ("ASC 808"). To the extent an arrangement falls within the scope of ASC 808, we assess whether aspects of the arrangement between us and our collaboration partner are within the scope of other accounting guidance, including ASC 606. Deferred Revenue We record a contract liability as deferred revenue on our unaudited condensed consolidated balance sheets when we receive payment but have not yet satisfied our related performance obligations specified in the sales or other contract. Revenue is recognized from deferred revenue in the period in which our obligations under the agreement are fulfilled or are proportionately recognized in the proportional amount of fulfillment. See Note 3 - ALJ Commercialization and License Agreement. Research and Development Costs Research and development costs are expensed in the period incurred. Research and development expenses consist of both internal and external costs associated with the development of our product candidates, such as payroll, consulting and manufacturing costs associated with the development of our product candidates. Costs for certain development activities, such as clinical trials and manufacturing development activities, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to us by our vendors on their actual costs incurred or level of effort expended. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the unaudited condensed consolidated balance sheets as prepaid or accrued research and development expenses. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed. We have and may continue to acquire the rights to develop and commercialize new product candidates from third parties. The upfront payments to acquire any license, product or rights, as well as any future milestone payments, are immediately recognized as research and development expense provided that there is no alternative future use of the rights in other research and development projects. Any milestone payments made for Intellectual Property after regulatory approval, or that have alternative future use, are capitalized and amortized. Stock-Based Compensation We record stock-based compensation for equity awards granted to employees and directors based on the grant date fair value of awards issued. The expense is recorded over the requisite service period, which is the vesting period, on a straight-line basis. We account for stock-based compensation arrangements with non-employees based upon the fair value of the consideration received or the equity instruments issued, whichever amount is more reliably measurable. We use the Black-Scholes option-pricing model to determine the fair value of option grants. We record forfeitures as they occur. Segments We have one operating segment. Our chief operating decision maker, our Chief Executive Officer, manages our operations on a consolidated basis for the purposes of allocating resources. Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. For purposes of the dilutive net loss per share applicable to common stockholders calculation, stock options, common stock from Employee Stock Purchase Plan, convertible debt, warrants to purchase common shares and unvested restricted stock are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. Recently Adopted Accounting Pronouncements Debt with Conversion and Other Options On August 5, 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU-2020-06”), which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. The guidance simplifies the evaluation of whether a contract in the issuer’s own equity can be classified in equity or an embedded feature qualifies for the derivative scope exception. We adopted the guidance for the year beginning January 1, 2022, The adoption has no impact on our consolidated financial statements and related disclosures. Codification Improvements In October 2020, the FASB issued ASU No. 2020-10 - Codification Improvements . The amendments improve the codification by having all disclosure-related guidance available in the disclosure sections of the codification and also includes various other minor amendments. We adopted the guidance for the year beginning January 1, 2022, with no impact on our consolidated financial statements and related disclosures. Accounting Pronouncements Issued and Not Adopted Financial Instruments - Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) — Measurement of Credit Losses on Financial Instruments , which was subsequently updated (together “ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology, and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for us on January 1, 2023, with early adoption permitted. We are currently evaluating the potential impact that this standard may have on our financial position and results of operations, as well as the timing of our adoption of this standard.

ALJ Commercialization and Licen

ALJ Commercialization and License Agreement	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ALJ Commercialization and License Agreement	ALJ Commercialization and License Agreement In March 2021, we entered into a commercialization and license agreement (“ALJ Agreement”) with ALJ. Pursuant to the ALJ Agreement, we granted to ALJ an exclusive, non-transferable, sublicensable license to our product candidate EDP1815. In consideration for the rights granted under the ALJ Agreement, ALJ was obligated to pay a one-time, non-refundable upfront fee of $7.5 million. The parties will also share the future operating profits and losses for certain products in certain territories equally (50:50) as well as certain development, regulatory and commercialization costs. We have concluded that the delivery of the license to ALJ shall be accounted for under ASC 606. The development, regulatory and commercialization activities within the territories shall be accounted for under ASC 808. We have recognized no revenue under the ALJ Agreement to date as we have yet to undertake any of our performance obligations within the agreement. The $7.5 million upfront fee was recorded as deferred revenue as a non-current liability in the accompanying unaudited condensed consolidated balance sheets as the performance obligation is not expected to be completed within the next twelve months. Mayo Foundation for Medical Education and Research In August 2017, we and the Mayo Clinic entered into a license agreement which was subsequently amended. Under the agreement, the Mayo Clinic granted us (i) an exclusive, worldwide, sublicensable license under the Mayo Clinic’s rights to certain intellectual property and microbial strains and (ii) a non-exclusive, worldwide, sublicensable license to certain related know-how to develop and commercialize certain microbial strains and licensed products incorporating such strains. As consideration, we paid a nonrefundable upfront fee of $0.3 million and are obligated to pay annual license maintenance fees. The nonrefundable upfront fees were expensed to research and development expense in 2017. Annual maintenance fees are expensed as incurred over the term of the agreement. We may owe the Mayo Clinic milestone payments upon the achievement of certain milestones up to a maximum of $59.1 million in the aggregate, as well as royalties on net sales of licensed products in low single-digit percentages. As of March 31, 2022, we incurred milestone payments since inception of approximately $0.3 million and no amounts are currently due. University of Chicago In March 2016, we and the University of Chicago entered into a patent license agreement (“2016 University of Chicago Agreement”). Under the agreement, the University of Chicago granted us (i) an exclusive, royalty-bearing and sublicensable license to certain patent rights related to the administration of microbes to treat cancer and (ii) a non-exclusive, royalty-bearing, sublicensable license to access technical information for the development and commercialization of microbial products to treat cancer in combination with checkpoint inhibitors. As consideration, we paid a nonrefundable upfront fee of less than $0.5 million and are obligated to pay annual license maintenance fees. Nonrefundable upfront fees were expensed to research and development expense in 2016. Annual maintenance fees are expensed as incurred over the term of the agreement. We may owe the University of Chicago milestone payments totaling an aggregate of approximately $60.9 million upon the achievement of certain milestones, as well as royalties on net sales of licensed products ranging from low to high single-digit percentages. As of March 31, 2022, we incurred milestone payments since inception of approximately $0.4 million and no amounts are currently due.

Leases

Leases	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Leases	Leases In January 2018, we entered into an operating sublease arrangement for approximately 40,765 square feet of office and research and development space at 620 Memorial Drive, Cambridge, MA 02139, extending through September 2025. The lease requires a security deposit which we fulfilled with a standing letter of credit secured by restricted cash on deposit. For the three months ended March 31, 2022 and 2021, we recorded rent expense of $0.8 million and $0.7 million, respectively. The minimum aggregate lease commitments as of March 31, 2022 are as follows (in thousands): Remainder of 2022 $ 2,049 2023 3,154 2024 3,249 2025 2,492 Total minimum lease payments 10,944 Less: imputed interest (1,734) Total operating lease liability $ 9,210 Operating cash flows used for operating leases $ 760 Weighted-average remaining lease term 3.5 years Weighted-average discount rate 9.5 %

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following presents the fair value hierarchy for financial assets measured at fair value on a recurring basis as of March 31, 2022 (in thousands): Total Level 1 Assets: Money market funds included in cash and cash equivalents $ 34,407 $ 34,407 Total $ 34,407 $ 34,407 The following presents the fair value hierarchy for financial assets measured at fair value on a recurring basis as of December 31, 2021 (in thousands): Total Level 1 Assets: Money market funds included in cash and cash equivalents $ 66,989 $ 66,989 Total $ 66,989 $ 66,989 As of March 31, 2022 and December 31, 2021, our financial assets measured at fair value consist entirely of assets measured at Level 1. There were no financial liabilities measured at fair value.

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment consists of the following (in thousands): March 31, 2022 December 31, 2021 Lab equipment $ 9,609 $ 9,689 Leasehold improvements 2,157 2,157 Furniture and fixtures 818 809 Computers and software 261 259 Office equipment 38 21 Construction-in-process 1,394 1,321 14,277 14,256 Less: accumulated depreciation (8,151) (7,634) Property and equipment, net $ 6,126 $ 6,622 We recognized $0.5 million and $0.5 million of depreciation expense for the three months ended March 31, 2022 and 2021, respectively.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2022
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following (in thousands): March 31, 2022 December 31, 2021 Accrued external research and development expenses $ 4,291 $ 4,895 Accrued payroll and related expenses 3,528 6,412 Accrued professional fees 1,282 1,013 Accrued other expenses 775 748 Total accrued expenses $ 9,876 $ 13,068

Loan and Security Agreements

Loan and Security Agreements	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Loan and Security Agreements	Loan and Security Agreements In July 2019, we entered into a loan and security agreement with K2 HealthVentures LLC and others (collectively, "K2HV"), under which K2HV agreed to extend term loans of up to $45.0 million in three tranches. The initial tranche of $20.0 million was funded in July 2019. The second tranche of $10.0 million was funded in July 2020. The availability of the third tranche of $15.0 million expired in January 2021. The facility was amended in June 2021 (the "Amended Credit Facility"), to supersede the expired $15.0 million third tranche commitment with a new $15.0 million fourth tranche commitment, which we drew down in June 2021. The Amended Credit Facility resulted in a debt extinguishment for accounting purposes and we recorded a loss on the extinguishment of debt of $3.2 million in the quarterly period ended June 30, 2021, equaling the difference between the fair value for reacquisition of the new debt and the carrying amount of the existing debt. In connection with the Amended Credit Facility, we issued to K2 HealthVentures Equity Trust LLC, an affiliate of K2HV, a warrant to purchase up to 139,770 shares of our common stock. In addition, K2HV has the option, exercisable at any time, to convert up to $5.0 million of principal outstanding into up to 375,940 shares of our common stock. Se e Note 11 - Stockholders' Equity. Interest on the outstanding loan balance accrues at a variable annual rate equal to the greater of (i) 8.65% and (ii) the prime rate plus 3.15%. Terms are for interest-only payments on a monthly basis through February 2023. Thereafter, terms provide for equal monthly payments of principal plus interest until the loans mature in August 2024 whereupon the remaining balance is due and payable. Pursuant to the Amended Credit Facility, we elected to adjust the repayment schedule such that commencing on March 1, 2023, we will make consecutive equal monthly payments of principal and accrued and unpaid interest based on a notional thirty month repayment period. The loan maturity date remains August 1, 2024 and any outstanding principal and unpaid interest is due at maturity. Upon final payment or prepayment of the loans, we will pay a final payment equal to 4.8% of the aggregate original principal amount of the loans borrowed. Borrowings under the Amended Credit Facility are collateralized by substantially all our tangible personal property along with our equity interests in our subsidiaries. The Amended Credit Facility contains customary representations, warranties and covenants . As of March 31, 2022, we were in compliance with all such covenants. The minimum future loan payments under the Amended Credit Facility as of March 31, 2022 are as follows (in thousands): Remainder of 2022 $ 2,974 2023 17,404 2024 34,770 Total minimum payments 55,148 Less: amounts representing interest and discount (8,532) Total debt $ 46,616

In-License Agreements

In-License Agreements	3 Months Ended
	Mar. 31, 2022
Research and Development [Abstract]
In-License Agreements	ALJ Commercialization and License Agreement In March 2021, we entered into a commercialization and license agreement (“ALJ Agreement”) with ALJ. Pursuant to the ALJ Agreement, we granted to ALJ an exclusive, non-transferable, sublicensable license to our product candidate EDP1815. In consideration for the rights granted under the ALJ Agreement, ALJ was obligated to pay a one-time, non-refundable upfront fee of $7.5 million. The parties will also share the future operating profits and losses for certain products in certain territories equally (50:50) as well as certain development, regulatory and commercialization costs. We have concluded that the delivery of the license to ALJ shall be accounted for under ASC 606. The development, regulatory and commercialization activities within the territories shall be accounted for under ASC 808. We have recognized no revenue under the ALJ Agreement to date as we have yet to undertake any of our performance obligations within the agreement. The $7.5 million upfront fee was recorded as deferred revenue as a non-current liability in the accompanying unaudited condensed consolidated balance sheets as the performance obligation is not expected to be completed within the next twelve months. Mayo Foundation for Medical Education and Research In August 2017, we and the Mayo Clinic entered into a license agreement which was subsequently amended. Under the agreement, the Mayo Clinic granted us (i) an exclusive, worldwide, sublicensable license under the Mayo Clinic’s rights to certain intellectual property and microbial strains and (ii) a non-exclusive, worldwide, sublicensable license to certain related know-how to develop and commercialize certain microbial strains and licensed products incorporating such strains. As consideration, we paid a nonrefundable upfront fee of $0.3 million and are obligated to pay annual license maintenance fees. The nonrefundable upfront fees were expensed to research and development expense in 2017. Annual maintenance fees are expensed as incurred over the term of the agreement. We may owe the Mayo Clinic milestone payments upon the achievement of certain milestones up to a maximum of $59.1 million in the aggregate, as well as royalties on net sales of licensed products in low single-digit percentages. As of March 31, 2022, we incurred milestone payments since inception of approximately $0.3 million and no amounts are currently due. University of Chicago In March 2016, we and the University of Chicago entered into a patent license agreement (“2016 University of Chicago Agreement”). Under the agreement, the University of Chicago granted us (i) an exclusive, royalty-bearing and sublicensable license to certain patent rights related to the administration of microbes to treat cancer and (ii) a non-exclusive, royalty-bearing, sublicensable license to access technical information for the development and commercialization of microbial products to treat cancer in combination with checkpoint inhibitors. As consideration, we paid a nonrefundable upfront fee of less than $0.5 million and are obligated to pay annual license maintenance fees. Nonrefundable upfront fees were expensed to research and development expense in 2016. Annual maintenance fees are expensed as incurred over the term of the agreement. We may owe the University of Chicago milestone payments totaling an aggregate of approximately $60.9 million upon the achievement of certain milestones, as well as royalties on net sales of licensed products ranging from low to high single-digit percentages. As of March 31, 2022, we incurred milestone payments since inception of approximately $0.4 million and no amounts are currently due.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Collaboration Agreement with Sacco S.r.l. In July 2019, we entered into an agreement with Sacco S.r.l. ("Sacco") pursuant to which Sacco will manufacture and supply single strain, non-genetically modified microbes intended for oral delivery or oral use in pharmaceutical products exclusively for us for a period of five years. Sacco may terminate the agreement if the provision of manufacturing services has been, or is scheduled to be, inactive for a period of six Litigation and Other Proceedings We may periodically become subject to legal proceedings and claims arising in connection with on-going business activities, including claims or disputes related to patents issued to us or that are pending. We are not a party to any material litigation and have established no contingency reserves for any litigation liability. On February 12, 2021, the European Patent Office issued a Communication of a Notice of Opposition for European patent EP 3223834 held by us. In July 2021, we filed our reply to the Notice of Opposition. In January 2022, the European Patent Office issued a preliminary opinion and a summons to oral proceedings. The deadline for final written submissions is in July 2022 and the date for the oral proceedings is in September 2022. We are currently evaluating our available options and deciding next steps with respect to this matter. The patent at issue does not relate to any of our current product candidates, and receipt of this communication and/or any subsequent proceeding is not expected to affect any of our current development plans.

Stockholders_ (Deficit) Equity

Stockholders’ (Deficit) Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Stockholders’ (Deficit) Equity	Stockholders’ (Deficit) Equity 2019 Shelf Registration In June 2019, we filed a Registration Statement on Form S-3 ("2019 Shelf Registration") with the Securities and Exchange Commission ("SEC") for the registration and offering of common stock, preferred stock, debt securities, warrants and/or units or any combination thereof in the aggregate amount of up to $200.0 million for a period of up to three years from the date of effectiveness. We simultaneously entered into an “at-the-market” sales agreement ("ATM") providing for the offering, issuance and sale for up to $50.0 million of common stock under the 2019 Shelf Registration. During the three months ended March 31, 2022, we issued no shares of common stock under the ATM. During the year ended December 31, 2021, we issued 139,734 common shares under the ATM with offering prices ranging between $12.54 and $13.17 per share for gross proceeds of $1.8 million and net proceeds of $1.7 million. February 2, 2021 Offering In February 2021, we sold 5,175,000 shares of common stock in an underwritten public offering under our 2019 Shelf Registration at a price of $15.00 per share, which included the underwriters' exercise of its option to purchase 675,000 shares, for gross proceeds of $77.6 million and net proceeds of $72.7 million. ALJ Health Care Private Placement In January 2021, we entered into a stock purchase agreement with ALJ Health Care & Life Science Company Limited ("ALJ Health") pursuant to which, on February 2, 2021, ALJ Health purchased 500,000 shares of common stock in a private placement for $15.00 per share, equal to the public offering price per share at which common stock was sold to the public as referred above. The placement generated proceeds of $7.5 million. The shares were not registered under the Securities Act of 1933, as amended. 2021 Shelf Registration In August 2021, we filed a Registration Statement on Form S-3 (“2021 Shelf Registration”) with the SEC for the registration and offering of common stock, preferred stock, debt securities, warrants and/or units or any combination thereof in the aggregate amount of up to $200.0 million for a period of up to three years from the date of effectiveness. During the three months ended March 31, 2022, we issued no shares of common stock under the 2021 Shelf Registration. No shares of common stock registered under the 2021 Shelf Registration were sold in the year ended December 31, 2021. Warrants In connection with our Amended Credit Facility (see Note 8 - Loan and Security Agreements), we issued K2 HealthVentures Equity Trust LLC a warrant to purchase up to 139,770 shares of our common stock with an exercise price of $13.30 per share, expiring in June 2031. The warrant holder has the option to exercise the purchase on a cashless basis. In addition, the warrant holder has the option, exercisable at any time, to convert up to $5.0 million of outstanding loan principal into up to 375,940 shares of common stock at a price of $13.30 per share.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation 2021 Inducement Plan In May, 2021, our board of directors adopted the Evelo Biosciences, Inc. 2021 Employment Inducement Award Plan (the “Inducement Award Plan”) without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Stock Market LLC listing rules (“Rule 5635(c)(4)”). In accordance with Rule 5635(c)(4), cash and equity-based incentive awards under the Inducement Award Plan may only be made to a newly-hired employee who was not previously a member of our board of directors, or to an employee who is rehired following a bona fide period of non-employment by us, as a material inducement to the employee’s entering into employment with us. An aggregate of 1,250,000 shares of our common stock were reserved for issuance under the Inducement Award Plan. The exercise price of stock options granted under the Inducement Award Plan will not be less than the fair market value of a share of our common stock on the grant date. Other terms of awards, including vesting requirements, are determined by our board of directors and are subject to the provisions of the Inducement Award Plan. Stock options granted to employees generally vest over a four-year period, but may be granted with different vesting terms. Certain options may provide for accelerated vesting in the event of a change in control. Stock options granted under the Inducement Award Plan expire no later than 10 years from the date of grant. As of March 31, 2022, stock option awards covering up to 800,000 shares of our common stock were issued under the Inducement Award Plan, none of which were exercised or canceled. As of March 31, 2022, restricted stock unit (“RSU”) awards covering up to 4,545 shares of our common stock were granted under the Inducement Award Plan, none of which have vested or forfeited. As of March 31, 2022, 445,455 shares of common stock are available for future grant under the Inducement Award Plan. 2018 Incentive Award Plan In April 2018, our board of directors adopted, and our stockholders approved, the 2018 Incentive Award Plan (the "2018 Plan"), effective in May 2018, under which we may grant cash and equity-based incentive awards to our employees, officers, directors, consultants and advisors. The 2018 Plan initially allowed us to grant awards for up to 1,344,692 shares of common stock plus that number of shares of common stock subject to awards outstanding under the 2015 Plan (as defined below) that expire, lapse, terminate or are exchanged for cash, surrendered, repurchased, canceled prior to exercise or forfeited following the effective date of the 2018 Plan. Each year starting with 2019 and ending in and including 2028, the number of shares available for grants of awards under the 2018 Plan will be increased automatically on January 1 by a number of shares of common stock equal to the lesser of 4% of the shares of common stock outstanding on the final day of the preceding calendar year or the number of shares determined by our board of directors. Accordingly, on January 1, 2022, 2021, 2020 and 2019, the number of shares authorized for issuance under the 2018 Plan was increased by 2,143,058, 1,898,805, 1,286,824 and 1,273,031 shares, respectively. The exercise price of stock options granted under the 2018 Plan shall be no less than the fair market value of a share of our common stock on the grant date. Other terms of awards, including vesting requirements, are determined by the board of directors and are subject to the provisions of the 2018 Plan. Stock options granted to employees generally vest over a four-year period, but may be granted with different vesting terms. Certain options provide for accelerated vesting in the event of a change in control. Awards granted to non-employee consultants generally vest monthly over a period of one 2015 Stock Incentive Plan We previously granted equity awards under the 2015 Stock Incentive Plan (the "2015 Plan"), which originally provided for grant of incentive stock options, non-qualified stock options, RSAs and other stock-based awards to our employees, officers, directors, consultants and advisors. Following the effectiveness of the 2018 Plan, we ceased making grants under the 2015 Plan. The 2015 Plan continues to govern the terms and conditions of the outstanding awards granted under it. The terms of equity award agreements made under the 2015 Plan, including vesting requirements, were determined by the board of directors and are subject to the provisions of the 2015 Plan. Stock options granted to employees generally vest over a four-year period but may be granted with different vesting terms. A limited number of awards contain performance-based vesting criteria and for such awards that are deemed probable of vesting, we record expense in the period in which such determination is made through any remaining estimated vesting period. Certain options provide for accelerated vesting in the event of a change in control. Awards granted to non-employee consultants generally vest monthly over a period of one Under the 2015 Plan, we were authorized to grant equity awards up to an aggregate of 5,417,044 shares of common stock. As of March 31, 2022, an aggregate of 5,758,518 options and other equity awards were granted under the 2015 Plan, of which 1,471,337 were exercised, 1,299,392 were canceled and 18,468 were repurchased as of March 31, 2022. A total of 113,006 shares previously reserved under the 2015 Plan that had not been exercised or were otherwise subject to outstanding exercise awards were no longer authorized as of May 8, 2018. Stock-Based Compensation Expense Stock-based compensation expense recorded in our unaudited condensed consolidated statements of operations consists of the following (in thousands): Three Months Ended March 31, 2022 2021 Research and development 2,036 1,823 General and administrative $ 2,239 $ 1,441 Total stock-based compensation expense 4,275 $ 3,264 Stock Options A summary of our stock option activity is as follows: Shares Weighted- Options outstanding as of December 31, 2021 9,713,182 $ 9.32 Granted 1,746,005 $ 5.03 Exercised — $ — Canceled (219,185) $ 10.10 Options outstanding as of March 31, 2022 11,240,002 $ 8.65 Exercisable as of March 31, 2022 5,577,736 $ 7.13 The weighted-average fair value of options granted during the three months ended March 31, 2022 and 2021 was $3.77 and $12.07, respectively. As of March 31, 2022, total unrecognized stock-based compensation expense relating to unvested stock options was $35.9 million, expected to be recognized over a weighted average period of 2.82 years. Restricted Stock Units We issue restricted stock units ("RSU") under the 2018 Plan and the 2021 Inducement Award Plan. Typically, each award of RSUs vests as to 25% on the first anniversary of the grant date, and either monthly thereafter or annually over three additional years. A summary of RSU activity is as follows: Shares Weighted- Unvested as of December 31, 2021 320,209 $ 9.04 Granted 108,375 $ 5.05 Vested (35,406) $ 15.44 Forfeited (26,867) $ 8.75 Unvested as of March 31, 2022 366,311 $ 7.26 Stock-based compensation expense related to RSUs was $0.4 million and $0.2 million for the three months ended March 31, 2022 and 2021, respectively. 2018 Employee Stock Purchase Plan In April 2018, our board of directors adopted and our stockholders approved the 2018 Employee Stock Purchase Plan (“ESPP”), which became effective in May 2018. Under the terms of the ESPP, the number of shares of common stock that may be issued under the ESPP automatically increases on the first day of each calendar year, beginning in 2020 and ending in and including 2028, by an amount equal to the lesser of (i) 1% of the number of shares of our common stock outstanding on the last day of the applicable preceding calendar year and (ii) an amount determined by our board of directors. Accordingly, on January 1, 2022 and 2021, the number of shares authorized by our board of directors for issuance under the ESPP was increased by 535,765 and 474,701 shares, respectively. There were no additional share increases for the years 2020 and 2019. A total of 36,329 shares and 27,587 shares were purchased under the ESPP during the three months ended March 31, 2022 and 2021, respectively. Compensation expense related to our ESPP for the three months ended March 31, 2022 and 2021 was not material. As of March 31, 2022 and December 31, 2021, a total of 1,235,532 shares and 736,096 shares of common stock were reserved for issuance under the ESPP.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended March 31, 2022 and 2021 we recorded a tax provision of $0.1 million and $0.1 million respectively, primarily related to our wholly owned UK subsidiary. As of March 31, 2022 and December 31, 2021, the balance in accrued expenses in the unaudited condensed consolidated balance sheets for deferred employer payroll taxes pursuant to the CARES Act was $0.2 million each.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic and diluted net loss per common share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period, as follows (net loss in thousands): Three Months Ended March 31, 2022 2021 Numerator Net loss $ (29,861) (28,196) Denominator Weighted average shares outstanding used in computing net loss per share 53,619,635 51,343,923 Net loss per share, basic and diluted $ (0.56) $ (0.55) We compute diluted net loss per common share by giving consideration to all potentially dilutive common shares, except where the effect of including such securities would be antidilutive. We have reported net losses since inception and, as such, have determined that all potentially dilutive common shares are anti-dilutive. Basic and diluted net loss per share of common stock were the same for all periods presented as the impact of all potentially dilutive securities outstanding was anti-dilutive. The following table presents securities excluded from the computation of diluted weighted-average shares outstanding for the periods presented, as they are anti-dilutive: Three Months Ended March 31, 2022 2021 Unvested common stock from early exercise of options — 18,386 Stock options to purchase common stock 11,240,002 8,290,500 Warrant 139,770 — RSUs 366,311 385,250 Convertible debt (as-converted to common stock) 375,940 — Common stock offering from ESPP 26,588 7,786 Total securities excluded 12,148,611 8,701,922

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions We receive clinical advisory services from Weatherden Ltd. (“Weatherden”) under agreements that were entered into during 2017 and 2018. Duncan McHale, our Chief Medical Officer, is a part owner of Weatherden. During the three months ended March 31, 2022 and 2021, we paid Weatherden $0.1 million or less, respectively. As of March 31, 2022 and December 31, 2021, the amounts owed to Weatherden under the supply of service agreement were approximately $0.1 million or less, respectively. In September 2019, we entered into a consulting agreement with David Epstein (the "Consulting Agreement"), our Chairman of the Board, for strategic advisory and other consulting services. The Consulting Agreement was amended in October 2020 and again in April 2021, and now has a term that is scheduled to end on June 30, 2022 unless earlier terminated pursuant to its terms. In accordance with the initial terms of the Consulting Agreement, Mr. Epstein was granted an option to purchase 75,000 shares of common stock, vesting in 36 equal monthly installments and subject to his continued provision of consulting services on the applicable vesting dates. Under the Consulting Agreement as amended in October 2020, Mr. Epstein was also entitled to receive (i) an annual equity award on each anniversary of the effective date of the Consulting Agreement in the form of an option to purchase shares of common stock having a grant date fair market value of approximately $0.2 million as determined by the Board in its discretion based on customary option pricing methodologies, vesting in 12 equal monthly installments and subject to his continued provision of consulting services on the applicable vesting date, and (ii) an aggregate annual cash consulting fee of $0.3 million. In the event the Consulting Agreement is renewed for a term of less than one year, the equity award and the number of shares of common stock shall be adjusted proportionately to the length of the renewal term. In October 2020, in connection with the commencement of his second year of service as a consultant, Mr. Epstein was granted an option to purchase 44,743 shares of common stock, vesting in nine equal monthly installments and subject to his continued provision of consulting services on the vesting dates. Under the Consulting Agreement as amended in April 2021 and effective on June 30, 2021, Mr. Epstein is entitled to receive

Defined Contribution Plan

Defined Contribution Plan	3 Months Ended
	Mar. 31, 2022
Retirement Benefits [Abstract]
Defined Contribution Plan	Defined Contribution PlanWe provide benefits under certain retirement benefit plans. Our most significant defined contribution plan is in the United States, which is administered through a third-party administrator. Under the U.S. defined contribution plan, employees may elect to defer up to 85.0% of their compensation per year (subject to a maximum limit prescribed by federal tax law) and we match a portion of such employee contributions. For each of the three months ended March 31, 2022 and 2021, our matching contribution expense was $0.2 million.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsOn May 11, 2022, we notified the University of Chicago of our intent to terminate the 2016 University of Chicago Agreement, which we initially entered into in March 2016. None of our current or anticipated product candidates will be affected by the termination of licenses contained therein. The termination will be effective on July 11, 2022.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to, estimates related to the application of Revenue from Contracts with Customers (Topic 606) ("ASC 606") to our collaboration agreement with Meddist Company Limited (" ALJ"), the accrual of research and development expenses, the expected future lives of property and equipment and the valuation of stock-based awards. We base our estimates on historical experience and market-specific or other relevant assumptions that we believe to be reasonable under the circumstances. Actual results could differ from those estimates.
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of our business and our wholly owned and controlled subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Subsequent Event Considerations	Subsequent Event Considerations We consider events or transactions that occur after the balance sheet date but prior to the issuance of the unaudited condensed consolidated financial statements to identify matters that require additional disclosure or that may significantly affect currently reported financial condition such as our judgments related to estimates. Subsequent events were evaluated as required. Those events determined to be sufficiently material are described in Note 17 - Subsequent Events.
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially expose us to concentrations of credit risk primarily consist of cash and cash equivalents. We place our cash and cash equivalents primarily in two custodian accounts at accredited financial institutions. Such deposits have and will continue to exceed federally insured limits. As of March 31, 2022 and December 31, 2021, we have no off-balance sheet risk such as foreign exchange contracts, option contracts, derivatives or other foreign hedging arrangements.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of net loss and changes in equity during a period arising from transactions and other equity and circumstances, of which we have none. Our comprehensive loss equals our net loss for all periods presented.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted CashCash equivalents are comprised of highly liquid investments that are readily convertible into cash with original maturities of three months or less, comprised of cash held in banks and amounts held in money market funds. Cash equivalents are stated at cost, which approximates market value. Our restricted cash consists of restricted cash in connection with building leases for our office and laboratory premises and deposits held in relation to our credit card facility.
Fair Value of Financial Instruments	Fair Value of Financial Instruments FASB ASC 820, Fair Value Measurement (“ASC 820”) establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and our own assumptions (unobservable inputs). As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and • Level 3 inputs are unobservable inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment we exercised in determining fair value is greatest for instruments categorized in Level 3.
Property and Equipment	Property and Equipment Property and equipment consists of computer hardware and software, furniture and fixtures, office equipment, research and lab equipment and leasehold improvement recorded at cost. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets. A summary of the estimated useful lives of our property and equipment is as follows: Computer hardware 3 to 5 years Computer software 3 years Furniture and fixtures 7 years Research and laboratory equipment (used/new) 3 to 5 years Leasehold improvements Lesser of asset life or remaining life of lease Assets acquired and not placed in service are recorded to construction-in-process and are not depreciated. Assets are recorded according to classification and depreciated upon placement in service. Repairs and maintenance costs are expensed as incurred.
Impairment of Long-Lived Assets	We periodically evaluate property and equipment for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. We neither identified nor recorded any material impairment charges during the periods presented.
Income Taxes	Income Taxes We record deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. We account for interest and penalties related to uncertain tax positions as part of our provision for income taxes. A valuation allowance is provided to reduce the net deferred tax assets to the amount that will more likely than not be realized. We have incurred net losses since inception and, in recognition of the uncertainty in the realization of favorable tax attributes in future tax returns, we recorded a full valuation allowance against our otherwise recognizable net deferred tax assets.
Revenue Recognition	Revenue Recognition We recognize revenue under the Financial Accounting Standards Board guidance of ASC 606. Since inception, we have entered into one contract subject to ASC 606, however, as discussed in Note 3 - ALJ Commercialization and License Agreement, all revenue pursuant to this arrangement has been deferred. Deferred Revenue We record a contract liability as deferred revenue on our unaudited condensed consolidated balance sheets when we receive payment but have not yet satisfied our related performance obligations specified in the sales or other contract. Revenue is recognized from deferred revenue in the period in which our obligations under the agreement are fulfilled or are proportionately recognized in the proportional amount of fulfillment. See Note 3 - ALJ Commercialization and License Agreement.
Collaborative Agreements	Collaboration Agreements We analyze our collaboration arrangements under the Financial Accounting Standards Board guidance of Collaborative Arrangements (Topic 808)
Research and Development Costs	Research and Development Costs Research and development costs are expensed in the period incurred. Research and development expenses consist of both internal and external costs associated with the development of our product candidates, such as payroll, consulting and manufacturing costs associated with the development of our product candidates. Costs for certain development activities, such as clinical trials and manufacturing development activities, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to us by our vendors on their actual costs incurred or level of effort expended. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the unaudited condensed consolidated balance sheets as prepaid or accrued research and development expenses. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.
Stock-Based Compensation	Stock-Based CompensationWe record stock-based compensation for equity awards granted to employees and directors based on the grant date fair value of awards issued. The expense is recorded over the requisite service period, which is the vesting period, on a straight-line basis. We account for stock-based compensation arrangements with non-employees based upon the fair value of the consideration received or the equity instruments issued, whichever amount is more reliably measurable. We use the Black-Scholes option-pricing model to determine the fair value of option grants. We record forfeitures as they occur.
Segments	Segments We have one operating segment. Our chief operating decision maker, our Chief Executive Officer, manages our operations on a consolidated basis for the purposes of allocating resources.
Net Loss per Share	Net Loss per ShareBasic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. For purposes of the dilutive net loss per share applicable to common stockholders calculation, stock options, common stock from Employee Stock Purchase Plan, convertible debt, warrants to purchase common shares and unvested restricted stock are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented.
Recently Adopted Accounting Pronouncements and Accounting Pronouncements Issued and Not Adopted	Recently Adopted Accounting Pronouncements Debt with Conversion and Other Options On August 5, 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU-2020-06”), which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. The guidance simplifies the evaluation of whether a contract in the issuer’s own equity can be classified in equity or an embedded feature qualifies for the derivative scope exception. We adopted the guidance for the year beginning January 1, 2022, The adoption has no impact on our consolidated financial statements and related disclosures. Codification Improvements In October 2020, the FASB issued ASU No. 2020-10 - Codification Improvements . The amendments improve the codification by having all disclosure-related guidance available in the disclosure sections of the codification and also includes various other minor amendments. We adopted the guidance for the year beginning January 1, 2022, with no impact on our consolidated financial statements and related disclosures. Accounting Pronouncements Issued and Not Adopted Financial Instruments - Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) — Measurement of Credit Losses on Financial Instruments , which was subsequently updated (together “ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology, and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for us on January 1, 2023, with early adoption permitted. We are currently evaluating the potential impact that this standard may have on our financial position and results of operations, as well as the timing of our adoption of this standard.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following reconciles cash, cash equivalents and restricted cash as of March 31, 2022 and December 31, 2021, as presented on our statements of cash flows to the related balance sheet accounts (in thousands): March 31, 2022 December 31, 2021 Cash and cash equivalents: Cash $ 5,224 $ 1,452 Money market funds 34,407 66,989 Total cash and cash equivalents 39,631 68,441 Restricted cash 1,155 1,313 Cash, cash equivalents and restricted cash $ 40,786 $ 69,754
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following reconciles cash, cash equivalents and restricted cash as of March 31, 2022 and December 31, 2021, as presented on our statements of cash flows to the related balance sheet accounts (in thousands): March 31, 2022 December 31, 2021 Cash and cash equivalents: Cash $ 5,224 $ 1,452 Money market funds 34,407 66,989 Total cash and cash equivalents 39,631 68,441 Restricted cash 1,155 1,313 Cash, cash equivalents and restricted cash $ 40,786 $ 69,754
Schedule of Estimated Useful Lives of Property and Equipment	A summary of the estimated useful lives of our property and equipment is as follows: Computer hardware 3 to 5 years Computer software 3 years Furniture and fixtures 7 years Research and laboratory equipment (used/new) 3 to 5 years Leasehold improvements Lesser of asset life or remaining life of lease Property and equipment consists of the following (in thousands): March 31, 2022 December 31, 2021 Lab equipment $ 9,609 $ 9,689 Leasehold improvements 2,157 2,157 Furniture and fixtures 818 809 Computers and software 261 259 Office equipment 38 21 Construction-in-process 1,394 1,321 14,277 14,256 Less: accumulated depreciation (8,151) (7,634) Property and equipment, net $ 6,126 $ 6,622

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Schedule of Minimum Aggregate Future Lease Commitments	The minimum aggregate lease commitments as of March 31, 2022 are as follows (in thousands): Remainder of 2022 $ 2,049 2023 3,154 2024 3,249 2025 2,492 Total minimum lease payments 10,944 Less: imputed interest (1,734) Total operating lease liability $ 9,210 Operating cash flows used for operating leases $ 760 Weighted-average remaining lease term 3.5 years Weighted-average discount rate 9.5 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value	The following presents the fair value hierarchy for financial assets measured at fair value on a recurring basis as of March 31, 2022 (in thousands): Total Level 1 Assets: Money market funds included in cash and cash equivalents $ 34,407 $ 34,407 Total $ 34,407 $ 34,407 The following presents the fair value hierarchy for financial assets measured at fair value on a recurring basis as of December 31, 2021 (in thousands): Total Level 1 Assets: Money market funds included in cash and cash equivalents $ 66,989 $ 66,989 Total $ 66,989 $ 66,989

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Estimated Useful Lives of Property and Equipment	A summary of the estimated useful lives of our property and equipment is as follows: Computer hardware 3 to 5 years Computer software 3 years Furniture and fixtures 7 years Research and laboratory equipment (used/new) 3 to 5 years Leasehold improvements Lesser of asset life or remaining life of lease Property and equipment consists of the following (in thousands): March 31, 2022 December 31, 2021 Lab equipment $ 9,609 $ 9,689 Leasehold improvements 2,157 2,157 Furniture and fixtures 818 809 Computers and software 261 259 Office equipment 38 21 Construction-in-process 1,394 1,321 14,277 14,256 Less: accumulated depreciation (8,151) (7,634) Property and equipment, net $ 6,126 $ 6,622

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2022
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): March 31, 2022 December 31, 2021 Accrued external research and development expenses $ 4,291 $ 4,895 Accrued payroll and related expenses 3,528 6,412 Accrued professional fees 1,282 1,013 Accrued other expenses 775 748 Total accrued expenses $ 9,876 $ 13,068

Loan and Security Agreements (T

Loan and Security Agreements (Tables)	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Schedule of Minimum Aggregate Future Loan Payments	The minimum future loan payments under the Amended Credit Facility as of March 31, 2022 are as follows (in thousands): Remainder of 2022 $ 2,974 2023 17,404 2024 34,770 Total minimum payments 55,148 Less: amounts representing interest and discount (8,532) Total debt $ 46,616

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Summary of Stock-based Compensation Expense	Stock-based compensation expense recorded in our unaudited condensed consolidated statements of operations consists of the following (in thousands): Three Months Ended March 31, 2022 2021 Research and development 2,036 1,823 General and administrative $ 2,239 $ 1,441 Total stock-based compensation expense 4,275 $ 3,264
Summary of Stock Option Activity	A summary of our stock option activity is as follows: Shares Weighted- Options outstanding as of December 31, 2021 9,713,182 $ 9.32 Granted 1,746,005 $ 5.03 Exercised — $ — Canceled (219,185) $ 10.10 Options outstanding as of March 31, 2022 11,240,002 $ 8.65 Exercisable as of March 31, 2022 5,577,736 $ 7.13
Summary of Restricted Stock Unit Activity	A summary of RSU activity is as follows: Shares Weighted- Unvested as of December 31, 2021 320,209 $ 9.04 Granted 108,375 $ 5.05 Vested (35,406) $ 15.44 Forfeited (26,867) $ 8.75 Unvested as of March 31, 2022 366,311 $ 7.26

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted net loss per common share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period, as follows (net loss in thousands): Three Months Ended March 31, 2022 2021 Numerator Net loss $ (29,861) (28,196) Denominator Weighted average shares outstanding used in computing net loss per share 53,619,635 51,343,923 Net loss per share, basic and diluted $ (0.56) $ (0.55)
Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares Outstanding	The following table presents securities excluded from the computation of diluted weighted-average shares outstanding for the periods presented, as they are anti-dilutive: Three Months Ended March 31, 2022 2021 Unvested common stock from early exercise of options — 18,386 Stock options to purchase common stock 11,240,002 8,290,500 Warrant 139,770 — RSUs 366,311 385,250 Convertible debt (as-converted to common stock) 375,940 — Common stock offering from ESPP 26,588 7,786 Total securities excluded 12,148,611 8,701,922

Organization and Basis of Pre_2

Organization and Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restricted cash equivalents	$ 40,786	$ 69,754	$ 126,154	$ 70,420
Accumulated deficit	$ (444,556)	$ (414,695)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)segment	Dec. 31, 2021USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Number of operating segments | segment	1
Other Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Noncurrent restricted cash | $	$ 1.2	$ 1.3

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents:
Cash	$ 5,224	$ 1,452
Money market funds	34,407	66,989
Cash and cash equivalents	39,631	68,441
Restricted cash	1,155	1,313
Cash, cash equivalents and restricted cash	$ 40,786	$ 69,754	$ 126,154	$ 70,420

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Details)	3 Months Ended
	Mar. 31, 2022
Computer hardware | Minimum
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	3 years
Computer hardware | Maximum
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	5 years
Computer software
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	7 years
Research and laboratory equipment (used/new) | Minimum
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	3 years
Research and laboratory equipment (used/new) | Maximum
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	5 years

ALJ Commercialization and Lic_2

ALJ Commercialization and License Agreement (Details) - USD ($) $ in Thousands	Mar. 17, 2021	Mar. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue recognized		$ 7,500	$ 7,500
Transaction with party to collaborative arrangement | ALJ
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue recognized		$ 7,500
Share of operating profits and losses and development, regulatory and commercialization costs.	50.00%

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)	Jan. 31, 2018a
Leases [Abstract]
Area of leased office and research development space (in square feet) | a			40,765
Rent expense | $	$ 0.8	$ 0.7

Leases - Schedule of Minimum Ag

Leases - Schedule of Minimum Aggregate Future Lease Commitments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Leases [Abstract]
Remainder of 2022	$ 2,049
2023	3,154
2024	3,249
2025	2,492
Total minimum lease payments	10,944
Less: imputed interest	(1,734)
Total operating lease liability	9,210
Operating cash flows used for operating leases	$ 760
Weighted-average remaining lease term	3 years 6 months
Weighted-average discount rate	9.50%

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Total	$ 34,407	$ 66,989
Money market funds
Assets:
Money market funds	34,407	66,989
Level 1
Assets:
Total	$ 34,407	$ 66,989

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property and equipment:
Property, Plant and Equipment, Gross	$ 14,277	$ 14,256
Less: accumulated depreciation	(8,151)	(7,634)
Property and equipment, net	6,126	6,622
Lab equipment
Property and equipment:
Property, Plant and Equipment, Gross	9,609	9,689
Leasehold improvements
Property and equipment:
Property, Plant and Equipment, Gross	2,157	2,157
Furniture and fixtures
Property and equipment:
Property, Plant and Equipment, Gross	818	809
Computer software
Property and equipment:
Property, Plant and Equipment, Gross	261	259
Office equipment
Property and equipment:
Property, Plant and Equipment, Gross	38	21
Construction-in-process
Property and equipment:
Property, Plant and Equipment, Gross	$ 1,394	$ 1,321

Property and Equipment, Net - N

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 517	$ 536

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Payables and Accruals [Abstract]
Accrued external research and development expenses	$ 4,291		$ 4,895
Accrued payroll and related expenses	3,528		6,412
Accrued professional fees	1,282		1,013
Accrued other expenses	775		748
Total accrued expenses	$ 9,876	$ 13,068	$ 13,068

Loan and Security Agreements -

Loan and Security Agreements - Narrative (Details)	1 Months Ended		3 Months Ended
	Jun. 30, 2021USD ($)	Jul. 31, 2019USD ($)tranche	Mar. 31, 2022USD ($)shares	Mar. 31, 2021USD ($)shares
Line of Credit Facility [Line Items]
Antidilutive securities | shares			12,148,611	8,701,922
Principal amount of loans borrowed		4.80%
Warrant
Line of Credit Facility [Line Items]
Antidilutive securities | shares			139,770	0
Convertible debt (as-converted to common stock)
Line of Credit Facility [Line Items]
Antidilutive securities | shares			375,940	0
2019 Credit Facility
Line of Credit Facility [Line Items]
Interest expense			$ 1,000,000	$ 800,000
Line of Credit | 2019 Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity (up to)		$ 45,000,000
Number of tranches | tranche		3
Loan and security agreement, interest rate		8.65%
Line of Credit | 2019 Credit Facility | Security And Loan Agreement, Tranche One
Line of Credit Facility [Line Items]
Maximum borrowing capacity (up to)		$ 20,000,000
Line of Credit | 2019 Credit Facility | Security And Loan Agreement, Tranche Two
Line of Credit Facility [Line Items]
Maximum borrowing capacity (up to)		10,000,000
Line of Credit | 2019 Credit Facility | Security And Loan Agreement, Tranche Three
Line of Credit Facility [Line Items]
Maximum borrowing capacity (up to)	$ 15,000,000	15,000,000
Line of Credit | 2019 Credit Facility | Security And Loan Agreement, Tranche Four
Line of Credit Facility [Line Items]
Maximum borrowing capacity (up to)		$ 15,000,000
Line of Credit | 2019 Credit Facility | Prime Plus
Line of Credit Facility [Line Items]
Loan and security agreement, basis spread on interest rate		3.15%
Line of Credit | Amended Credit Facility
Line of Credit Facility [Line Items]
Loss on extinguishment of debt	3,200,000
Convertible debt (up to)	$ 5,000,000

Loan and Security Agreements _2

Loan and Security Agreements - Schedule of Minimum Aggregate Future Loan Payments (Details) $ in Thousands	Mar. 31, 2022USD ($)
Line of Credit Facility [Line Items]
Total debt	$ 46,616
Line of Credit
Line of Credit Facility [Line Items]
Remainder of 2022	2,974
2023	17,404
2024	34,770
Total minimum payments	55,148
Less: amounts representing interest and discount	$ (8,532)

In-License Agreements - Narrati

In-License Agreements - Narrative (Details) - USD ($)	Mar. 31, 2022	Aug. 06, 2017	Mar. 10, 2016
Mayo Clinic
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront fee		$ 300,000
Milestone payments upon achievement of certain development, regulatory, and commercial events (up to)	$ 300,000
Mayo Clinic | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments upon achievement of certain development, regulatory, and commercial events (up to)		$ 59,100,000
University of Chicago Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments upon achievement of certain development, regulatory, and commercial events (up to)			$ 60,900,000
Amount due under license agreement	0
Milestone payments for development and commercialization of licensed products	$ 400,000
University of Chicago Agreement | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront fee			$ 500,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - Sacco - Collaborative Arrangement € in Millions, $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended			33 Months Ended
	Jul. 31, 2019EUR (€)	Mar. 31, 2025USD ($)	Dec. 31, 2024USD ($)	Dec. 31, 2023USD ($)	Dec. 31, 2022USD ($)	Mar. 31, 2022EUR (€)
Commitment And Contingencies [Line Items]
Term of collaboration arrangement	5 years
Period of inactive manufacturing services causing termination under collaborative arrangement	6 months
Aggregate amount due under collaborative arrangement	€ 3
Annual amount due under collaborative arrangement	€ 0.6
Fee incurred under collaborative arrangement						€ 1.8
Forecast
Commitment And Contingencies [Line Items]
Collaboration arrangement additional fee incured | $		$ 0.9	$ 1.5	$ 1.5	$ 1.5

Stockholders_ (Deficit) Equity

Stockholders’ (Deficit) Equity (Details) - USD ($)	Aug. 23, 2021	Feb. 02, 2021	Jan. 28, 2021	Jun. 30, 2019	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Jun. 30, 2021
Class of Stock [Line Items]
Sale of stock, term (up to)	3 years			3 years
Number of shares called by warrants (in shares) (up to)							0
Antidilutive securities					12,148,611	8,701,922
Warrant
Class of Stock [Line Items]
Antidilutive securities					139,770	0
Convertible debt (as-converted to common stock)
Class of Stock [Line Items]
Antidilutive securities					375,940	0
Line of Credit | Amended Credit Facility
Class of Stock [Line Items]
Common stock at a conversion price (in dollars per share)								$ 13.30
Convertible debt (up to)								$ 5,000,000
Registration Statement
Class of Stock [Line Items]
Maximum value of shares issued in transaction (up to)	$ 200,000,000			$ 200,000,000
At-the-market
Class of Stock [Line Items]
Maximum value of shares issued in transaction (up to)				$ 50,000,000
Number of shares sold in public offering (in shares)					0		139,734
Gross proceeds from transactions							$ 1,800,000
Net proceeds from issuance of common stock							$ 1,700,000
At-the-market | Minimum
Class of Stock [Line Items]
Price of shares sold in public offering (in dollars per share)							$ 12.54
At-the-market | Maximum
Class of Stock [Line Items]
Price of shares sold in public offering (in dollars per share)							$ 13.17
Public Stock Offering
Class of Stock [Line Items]
Number of shares sold in public offering (in shares)		5,175,000
Price of shares sold in public offering (in dollars per share)		$ 15
Gross proceeds from transactions		$ 77,600,000
Net proceeds from issuance of common stock		$ 72,700,000
Over-Allotment Option
Class of Stock [Line Items]
Number of shares sold in public offering (in shares)		675,000
Private Placement
Class of Stock [Line Items]
Number of shares sold in public offering (in shares)			500,000
Price of shares sold in public offering (in dollars per share)			$ 15
Net proceeds from issuance of common stock		$ 7,500,000

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands

Mar. 31, 2022

Jan. 01, 2022

Dec. 31, 2021

May 31, 2021

Jan. 01, 2021

Jan. 01, 2020

Jan. 01, 2019

Apr. 30, 2018

May 31, 2018

Mar. 31, 2022

Mar. 31, 2021

Dec. 31, 2015

Mar. 31, 2022

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of stock options granted (in shares)

1,746,005

Exercise of stock options (in shares)

0

Number of shares canceled (in shares)

219,185

Weighted average fair value of options granted (in dollars per share)

$ 3.77

$ 12.07

Total stock-based compensation expense

$ 4,275

$ 3,264

2021 Stock Inducement Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares originally authorized for issuance (in shares)

1,250,000

Number of common stock available for future grant (in shares)

445,455

445,455

445,455

2018 Stock Incentive Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares originally authorized for issuance (in shares)

1,344,692,000

Number of stock options granted (in shares)

8,824,136

Number of common stock available for future grant (in shares)

824,123

824,123

824,123

Percentage of outstanding shares

4.00%

Number of additional shares authorized for issuance (in shares)

2,143,058,000

1,898,805,000

1,286,824,000

1,273,031,000

Exercise of stock options (in shares)

43,247

Number of shares canceled (in shares)

1,328,684

2015 Stock Incentive Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of common stock available for future grant (in shares)

5,417,044,000

Number of shares, options and other equity awards granted (in shares)

5,758,518

Number of shares, options and other equity awards exercised (in shares)

1,471,337

Number of shares, options and other equity awards canceled (in shares)

1,299,392

Number of shares repurchased (in shares)

18,468,000

Number of shares no longer authorized (in shares)

113,006,000

Stock Options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Unrecognized compensation expense

$ 35,900

$ 35,900

$ 35,900

Compensation cost not yet recognized, period for recognition

2 years 9 months 25 days

Stock Options | 2021 Stock Inducement Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

4 years

Options granted, maximum expiration period (no more than)

10 years

Number of stock options granted (in shares)

800,000

Stock Options | 2018 Stock Incentive Plan | Maximum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Options granted, maximum expiration period (no more than)

10 years

Stock Options | 2018 Stock Incentive Plan | Employee

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

4 years

Stock Options | 2018 Stock Incentive Plan | Employee | Minimum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

1 year

Stock Options | 2018 Stock Incentive Plan | Employee | Maximum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

4 years

Stock Options | 2015 Stock Incentive Plan | Maximum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Options granted, maximum expiration period (no more than)

10 years

Stock Options | 2015 Stock Incentive Plan | Employee

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

4 years

Stock Options | 2015 Stock Incentive Plan | Employee | Minimum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

1 year

Stock Options | 2015 Stock Incentive Plan | Employee | Maximum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting period

4 years

RSUs

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

108,375

Total stock-based compensation expense

$ 400

$ 200

RSUs | Share-based Payment Arrangement, Tranche One

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting rights, percentage

25.00%

RSUs | 2021 Stock Inducement Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

4,545

Employee Stock Purchase Plan | 2018 Employee Stock Purchase Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Percentage of outstanding shares

1.00%

Number of additional shares authorized for issuance (in shares)

1,235,532

474,701

736,096

535,765

Number of shares issued for purchase (in shares)

36,329

27,587

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,275	$ 3,264
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,036	1,823
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,239	$ 1,441

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022
Shares
Options outstanding, beginning balance (in shares)	9,713,182
Granted (in shares)	1,746,005
Exercised (in shares)	0
Canceled (in shares)	(219,185)
Options outstanding, ending balance (in shares)	11,240,002
Exercisable as of period end (in shares)	5,577,736
Weighted- Average Exercise Price
Options outstanding, beginning balance (in dollars per share)	$ 9.32
Granted (in dollars per share)	5.03
Exercised (in dollars per share)	0
Canceled (in dollars per share)	10.10
Options outstanding, ending balance (in dollars per share)	8.65
Exercisable as of period end (in dollars per share)	$ 7.13

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - RSUs	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Shares
Unvested beginning balance (in shares) | shares	320,209
Granted (in shares) | shares	108,375
Vested (in shares) | shares	(35,406)
Forfeited (in shares) | shares	(26,867)
Unvested ending balance (in shares) | shares	366,311
Weighted- Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) | $ / shares	$ 9.04
Granted (in dollars per share) | $ / shares	5.05
Vested (in dollars per share) | $ / shares	15.44
Forfeited (in dollars per share) | $ / shares	8.75
Unvested ending balance (in dollars per share) | $ / shares	$ 7.26

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 116	$ 122
Deferred payroll taxes related to CARES Act	$ 200		$ 200

Net Loss Per Share - Weighted-A

Net Loss Per Share - Weighted-Average Common Shares Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net loss	$ (29,861)	$ (28,196)
Weighted average shares used in computing net loss per share, basic (in shares)	53,619,635	51,343,923
Weighted average shares used in computing net loss per share, diluted (in shares)	53,619,635	51,343,923
Net loss per share, diluted ( in dollars per share)	$ (0.56)	$ (0.55)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.56)	$ (0.55)
Accumulated Deficit
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net loss	$ (29,861)	$ (28,196)

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares Outstanding (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	12,148,611	8,701,922
Unvested common stock from early exercise of options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	0	18,386
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	11,240,002	8,290,500
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	139,770	0
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	366,311	385,250
Convertible debt (as-converted to common stock)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	375,940	0
Common stock offering from ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	26,588	7,786

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) $ in Millions	1 Months Ended		3 Months Ended		24 Months Ended
	Oct. 31, 2020USD ($)installmentshares	Sep. 30, 2019installmentshares	Mar. 31, 2022USD ($)shares	Mar. 31, 2021USD ($)	Jun. 30, 2021USD ($)installment
Related Party Transaction [Line Items]
Amounts due to related party			$ 0.1
Number of stock options granted (in shares) | shares			1,746,005
Weatherden Ltd
Related Party Transaction [Line Items]
Payment to related party				$ 0.1
Mr. Epstein | RSUs
Related Party Transaction [Line Items]
Aggregate grant date fair value for restricted stock units					$ 0.5
Mr. Epstein | Consulting Agreement
Related Party Transaction [Line Items]
Number of stock options granted (in shares) | shares	44,743	75,000
Option to purchase shares, vesting period, number of equal monthly installments | installment		36
Aggregate grant date fair value	$ 0.2
Annual equity award, vesting period, number of equal monthly installments | installment	12
Aggregate annual cash consulting fee	$ 0.3
Renewal term	1 year
Mr. Epstein | Consulting Agreement | RSUs
Related Party Transaction [Line Items]
Option to purchase shares, vesting period, number of equal monthly installments | installment					12
Period for trailing average closing common stock price					10 days
Mr. Epstein | Consulting Agreement | Stock options to purchase common stock
Related Party Transaction [Line Items]
Annual equity award, vesting period, number of equal monthly installments | installment	9

Defined Contribution Plan (Deta

Defined Contribution Plan (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Retirement Benefits [Abstract]
Defined contribution plan percent	85.00%
Defined contribution plan, cost	$ 0.2	$ 0.2