0001564590-22-010714 | 10-K | XBRL Viewer

Nature of Business

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

(1)	Nature of Business

Organization

Synlogic, Inc., together with its wholly owned and consolidated subsidiaries (Synlogic or the Company), is a clinical-stage biopharmaceutical company applying synthetic biology to the discovery and development of Synthetic Biotic medicines. Synthetic Biotic medicines are generated from Synlogic’s proprietary platform, leveraging a reproducible, modular approach to the generation of novel drug candidates that perform or deliver critical therapeutic functions. Synthetic Biotic medicines are designed to metabolize a toxic substance, compensate for missing or damaged metabolic pathways or deliver combinations of therapeutic factors. Synlogic’s goal is to discover, develop and ultimately commercialize Synthetic Biotic medicines. Since incorporation, the Company has devoted substantially all of its efforts to the research and development of its product candidates.

Risks and Uncertainties

At December 31, 2021, the Company had approximately $136.6 million in cash, cash equivalents, and marketable securities, $1.1 million of restricted cash and an accumulated deficit of approximately $290.9 million. Since its inception through December 31, 2021, the Company has primarily financed its operations through the issuance of preferred stock, units and warrants, the sale of its common stock, the Roche and AbbVie collaborations, and cash received in the Merger. In the absence of positive cash flows from operations, the Company is highly dependent on its ability to find additional sources of funding in the form of debt or equity financing. Management believes that the Company has sufficient cash to fund its operations through at least twelve months from the issuance of these financial statements.

As an early-stage company, the Company is subject to a number of risks common to other life science companies, including, but not limited to, raising additional capital, development by its competitors of new technological innovations, risk of failure in preclinical and clinical studies, safety and efficacy of its product candidates in clinical trials, the risk of relying on external parties such as contract research organizations (CROs) and contract manufacturing organizations (CMOs), the regulatory approval process, market acceptance of the Company’s products once approved, lack of marketing and sales history, dependence on key personnel and protection of proprietary technology. The Company’s therapeutic programs are currently pre-commercial, spanning discovery through early development and will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization of any product candidates. These efforts require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance-reporting capabilities. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company may never achieve profitability, and unless and until it does, it will continue to need to raise additional capital or obtain financing from other sources, such as strategic collaborations or alliances.

COVID-19

While the Company is not aware of a material impact from the continuation of the COVID-19 pandemic through December 31, 2021, the full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations, and financial condition, including expenses and manufacturing, clinical trials, and research and development costs, depends on future developments that are highly uncertain at this time.

Leases - Summary of Maturity of Lease Liabilities for Operating Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Leases
2022	$ 4,691
2023	3,574
2024	3,681
2025	3,791
2026	3,905
Thereafter	6,689
Total lease payments	26,331
Less: imputed interest	5,768
Total lease liabilities	20,563
Current lease liabilities	3,191	$ 2,531
Long-term lease liabilities	$ 17,372	$ 20,273

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (60,561)	$ (59,173)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	2,443	2,636
Equity-based compensation expense	3,361	3,907
Accretion/amortization of investment securities	261	(21)
Reduction in carrying amount of operating lease right of use asset	2,098	1,736
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,681	7,273
Prepaid research and development, net of current portion	281	6,791
Other assets	1	60
Accounts payable and accrued expenses	538	(349)
Deferred revenue	531	(544)
Operating lease liabilities	(2,701)	(2,000)
Other long-term liabilities	(131)	131
Net cash used in operating activities	(52,198)	(39,553)
Cash flows from investing activities:
Purchases of marketable securities	(167,866)	(86,474)
Proceeds from maturity of marketable securities	114,022	90,836
Proceeds from redemption of marketable securities	1,270	28,515
Purchases of property and equipment	(679)	(395)
Net cash (used in) provided by investing activities	(53,253)	32,482
Cash flows from financing activities:
Payments on finance lease obligations	(8)	(208)
Restricted stock awards withheld for payment of employees' withholding tax liability	(73)
Proceeds from issuance of common stock, net of issuance costs	81,042
Proceeds from employee stock purchases and exercise of stock options	374	58
Net cash provided by financing activities	89,382	13,394
Net (decrease) increase in cash, cash equivalents and restricted cash	(16,069)	6,323
Cash, cash equivalents and restricted cash at beginning of period	33,604	27,281
Cash, cash equivalents and restricted cash at end of period	17,535	33,604
Supplemental disclosure of non-cash investing activities:
Property and equipment purchases included in accounts payable and accrued expenses	40	(4)
Assets acquired under operating lease obligation	460
Supplemental disclosure of non-cash financing activities:
Purchase under finance lease	36
Issuance costs included in accounts payable and accrued expenses		10
Cash paid for interest	2	6
At-the-market Offering
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	$ 8,047	$ 13,544

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Schedule of Company's Classified Assets Measured at Fair Value on Recurring Basis

At December 31, 2021 and 2020, the Company has classified assets measured at fair value on a recurring basis as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	2021		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	16,437	$	16,437	$	—	$	—
Commercial paper		106,277		—		106,277		—
Corporate debt securities		5,873		—		5,873		—
U.S. government agency securities and treasuries		8,041		8,041		—		—
Total	$	136,628	$	24,478	$	112,150	$	—

	Fair Value Measurements at Reporting Date Using
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	2020		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	32,506	$	32,506	$	—	$	—
Commercial paper		40,477		—		40,477		—
Corporate debt securities		18,637		—		18,637		—
U.S. government agency securities and treasuries		8,823		8,823		—		—
Total	$	100,443	$	41,329	$	59,114	$	—

Equity-based Compensation and Equity Incentive Plans - Schedule of Weighted Average Assumption Used Black-Scholes Option-pricing Model for Stock Options Issued to Employees and Non-employees (Detail) - Employees and Nonemployees - 2015 and 2017 Plan	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	6 years 2 months 12 days	6 years 2 months 12 days
Weighted-average, risk-free interest rate	1.00%	0.60%
Expected volatility	84.90%	77.20%
Dividend yield	0.00%	0.00%

Related-Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Common stock, outstanding		69,698,844	38,183,273
Ginkgo Bioworks, Inc.
Related Party Transaction [Line Items]
Common stock, outstanding			6,340,771
Prepayment to related party for collaboration agreement	$ 30.0
Related party transaction collaboration agreement, initial term	5 years
Current pre-paid research and development		$ 1.9
Non-current pre-paid research and development		9.3
Prepaid research and development expenses		$ 2.4

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consists of the following (in thousands):

	December 31,			December 31,
	2021			2020
Laboratory equipment	$	8,274		$	7,793
Computer and office equipment		756			769
Furniture and fixtures		500			421
Leasehold improvements		9,561			9,514
Construction in progress		623			528
		19,714			19,025
Less accumulated depreciation		(10,626	)		(8,249	)
Property and equipment, net	$	9,088		$	10,776

Fair Value of Financial Instruments - Schedule of Company's Classified Assets Measured at Fair Value on Recurring Basis (Detail) - Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Asset Measured On Recurring Basis [Line Items]
Total assets	$ 136,628	$ 100,443
Money market funds
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	16,437	32,506
Commercial paper
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	106,277	40,477
U.S. Government Agency Securities and Treasuries
Fair Value Asset Measured On Recurring Basis [Line Items]
Short-term investments	8,041	8,823
Corporate debt securities
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	5,873	18,637
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Asset Measured On Recurring Basis [Line Items]
Total assets	24,478	41,329
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money market funds
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	16,437	32,506
Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. Government Agency Securities and Treasuries
Fair Value Asset Measured On Recurring Basis [Line Items]
Short-term investments	8,041	8,823
Significant Other Observable Inputs (Level 2)
Fair Value Asset Measured On Recurring Basis [Line Items]
Total assets	112,150	59,114
Significant Other Observable Inputs (Level 2) \| Commercial paper
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	106,277	40,477
Significant Other Observable Inputs (Level 2) \| U.S. Government Agency Securities and Treasuries
Fair Value Asset Measured On Recurring Basis [Line Items]
Short-term investments	0
Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	5,873	18,637
Significant Unobservable Inputs (Level 3)
Fair Value Asset Measured On Recurring Basis [Line Items]
Total assets	0	0
Significant Unobservable Inputs (Level 3) \| Money market funds
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	0	0
Significant Unobservable Inputs (Level 3) \| Commercial paper
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	0	0
Significant Unobservable Inputs (Level 3) \| U.S. Government Agency Securities and Treasuries
Fair Value Asset Measured On Recurring Basis [Line Items]
Short-term investments	0	0
Significant Unobservable Inputs (Level 3) \| Corporate debt securities
Fair Value Asset Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents	$ 0	$ 0

Leases - Summary of Weighted Average Remaining Lease Term and Weighted Average Discount Rate for Operating Leases (Detail)	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating Lease, Weighted average discount rate	8.00%	8.00%
Operating Lease, Weighted average remaining lease term (years)	6 years 3 months 18 days	7 years 2 months 12 days

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S.) (U.S. GAAP or GAAP).

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Synlogic and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities at the

date of the consolidated financial statements and the reported amounts of expenses during the reporting period. On an on-going basis, the Company’s management evaluates its estimates, including those related to revenue recognition, income taxes including the valuation allowance for deferred tax assets, research and development accruals and prepaids, accrued expenses, investments, contingencies and equity-based compensation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ from those estimates. Changes in estimates are reflected in reported results in the period in which they become known.

Cash Equivalents

The Company considers all highly liquid investment instruments with a remaining maturity when purchased of three months or less to be cash equivalents. Investments qualifying as cash equivalents consist of money market funds, including money market funds held in a sweep account. Cash equivalents are stated at cost plus accrued interest, which approximates fair value. The amount of cash equivalents included in cash and cash equivalents was approximately $16.4 million and $32.5 million at December 31, 2021 and 2020, respectively.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk include amounts held as cash, cash equivalents, marketable securities and restricted cash. The Company uses high quality, accredited financial institutions to maintain its balances, and accordingly, such funds are subject to minimal credit risk. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has no financial instruments with off-balance sheet risk of loss.

Restricted Cash

The Company held cash of approximately $1.1 million at December 31, 2021 and 2020 in a letter of credit to secure its lease at the 301 Binney Street facility. The Company has classified this deposit as long-term restricted cash on its balance sheet.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the statement of financial position that sum to the total of the same such amounts shown in the statement of cash flows (in thousands).

	December 31,		December 31,
	2021		2020
Cash and cash equivalents	$	16,438	$	32,507
Restricted cash		1,097		1,097
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows	$	17,535	$	33,604

Fair Value

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. Accounting Standards Codification (ASC) Topic 820, Fair Value Measurements and Disclosures, establishes a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:

•

Level 1 – Utilize observable inputs such as quoted prices in active markets for identical assets or liabilities;

•

Level 2 – Utilize data points that are either directly or indirectly observable, such as quoted prices, interest rates and yield curves;

•

Level 3 – Utilize unobservable data points in which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability.

The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1, Level 2 or Level 3 during the years ended December 31, 2021 and 2020.

Available-for-Sale Securities

The Company classifies all of its investments as available-for-sale based upon its intent with regard to such investments. The Company classifies investments as short-term when their remaining contractual maturities are one year or less from the balance sheet date, and as long-term when the investment has a remaining contractual maturity of more than one year from the balance sheet date. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income (loss). The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest and investment income. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities, are included in interest and investment income.

The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest and investment income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary.

Property and Equipment

Property and equipment, including leasehold improvements, are recorded at cost and depreciated over their estimated useful lives using the straight‑line method. Repairs and maintenance costs are expensed as incurred, whereas major improvements are capitalized as additions to property and equipment.

Depreciation begins at the time the asset is placed in service. Depreciation is provided over the following estimated useful lives:

Asset classification		Useful life
Computer and office equipment		3 years
Furniture and fixtures		5 years
Laboratory equipment		5 years
Leasehold improvements		Lesser of useful life or remaining lease term

Impairment of Long-Lived Assets

Impairment of Long‑Lived Assets

Long‑lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If this comparison indicates that there is impairment, the amount of impairment is calculated as the difference between the carrying value and fair value of the asset. To date, no such impairments have been recognized.

Leases

The Company uses judgement to assess if an arrangement is a lease at contract inception. An arrangement is a lease if the contract involves the use of a distinct identified asset, the lessor does not have substantive substitution rights and the Company obtains control of the asset throughout the period by obtaining substantially all of the economic benefit of the asset and the right to direct the use of the asset. Leases classified as operating leases are included in operating lease right-of-use (ROU) assets, current operating lease liabilities and noncurrent operating lease liabilities in our consolidated balance sheet. Finance leases are included in property and equipment and finance lease obligations in our consolidated balance sheet.

ROU assets represent the right-to-use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the estimated present value of lease payments over the lease term. The Company utilizes its incremental borrowing rate to determine the present value of lease payments. The incremental borrowing rate is the rate incurred to borrow similar funds, on a collateralized basis, over a comparable term in a similar economic environment.

The Company has elected to account for the lease and non-lease components for leases as a single component for classes of all underlying assets and allocate all of the contract consideration to the lease component only. Lease cost for operating leases is recognized on a straight-line basis over the lease term and is included in operating expenses on the statements of operations and comprehensive loss. Variable lease payments are included in lease operating expenses.

The lease term includes options to extend the lease when it is reasonably certain that option will be exercised. Leases with a term of 12 months or less are not recorded on the Company’s consolidated balance sheet.

Research and Development Costs

Costs incurred in research and development are expensed as incurred. The Company defers and capitalizes nonrefundable advance payments made by the Company for research and development activities until the related goods are received or the related services are performed.

Research and development expenses are comprised of costs incurred in performing research and development activities, including salary and benefits, equity-based compensation expense, laboratory supplies and other direct expenses, facilities expenses, overhead expenses, contractual services and other outside expenses.

When third-party service providers’ billing terms do not coincide with the Company’s period-end, the Company is required to make estimates of its obligations to those third parties, including clinical trial costs, contractual services costs and costs for supply of its drug candidates, incurred in a given accounting period and record accruals at the end of the period. The Company bases its estimates on the completion status of the research and development programs and the associated estimate of unbilled costs.

Revenue recognition

The Company generates revenue through a collaboration and option agreement with Roche for the development and commercialization of product candidates.

The Company evaluates collaboration agreements with respect to FASB ASC Topic 808, Collaborative Arrangements, considering the nature and contractual terms of the arrangement and the nature of its business operations to determine the classification of the transactions. When the Company is an active participant in the activity and exposed to significant risks and rewards dependent on the commercial success of the collaboration, it will record its transactions on a gross basis in the consolidated financial statements and describe the rights and obligations under the collaborative arrangement in the notes to the consolidated financial statements.

Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five-step analysis: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step analysis to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

The Company may enter into collaboration agreements for research and development services, under which the Company may license certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. Variable consideration is constrained until it is deemed not be at significant risk of reversal.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its agreements for which the collaboration partner is also a customer, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: a) the number of performance obligations based on the determination under step (ii) above; b) the transaction price under step (iii) above; and c) the contract term and pattern of satisfaction of the performance obligations under step (v) above. The Company uses significant judgment to determine whether milestones or other variable consideration, except for royalties, should

be included in the transaction price as described further below. The transaction price is allocated to the goods and services the Company expects to provide. The Company uses estimates to determine the timing of satisfaction of performance obligations, which may include the use of full-time equivalent time as a measure of satisfaction of performance obligations.

Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion.

Licenses of Intellectual Property

In assessing whether a promise or performance obligation is distinct from the other promises, we consider factors such as the research, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. In addition, we consider whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promises, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Research and Development Services

If an arrangement is determined to contain a promise or obligation for us to perform research and development services, we must determine whether these services are distinct from the other promises in the arrangement. In assessing whether the services are distinct from the other promises, we consider the capabilities of the customer to perform these same services. In addition, we consider whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promise, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For research and development services that are combined with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The estimates we use to record revenue relating to the combined performance obligation on an over time basis, include input methods such as full-time equivalent time incurred compared to the full-time equivalent time expected to be incurred in the future to satisfy the performance obligation, which require management judgment. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. With this method, we must estimate total inputs required to satisfy a performance obligation and measure efforts expended to date to determine revenue recognition. This estimate of remaining inputs is subjective, as the research is novel, and therefore efforts to be successful may be different than the estimated efforts at the balance sheet date.

Customer Options

If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, that is, the option to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on an alternative approach when the goods or services are both (i) similar to the original goods and services in the contract and (ii) provided in accordance with the terms of the original contract. Under this alternative, the Company allocates the total amount of consideration expected to be received from the customer to the total goods or services expected to be provided to the customer. Amounts allocated to a material right are not recognized as revenue until the option is exercised and the performance obligation is satisfied.

Milestone Payments

At the inception of each arrangement that includes milestone payments, the Company evaluates whether a significant reversal of cumulative revenue provided in conjunction with achieving the milestones is probable and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the

Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. For other milestones, the Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant reversal of cumulative revenue would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Royalties

For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements.

Contract Costs

The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer.

Equity-Based Compensation

Equity‑Based Compensation

The Company measures equity-based compensation to employees, non-employees and directors based on the grant date fair value of the awards and recognizes the associated expense in the financial statements over the requisite service period of the award, which is generally the vesting period. The fair value of each option and purchase rights under the employee stock purchase plan (ESPP) is estimated on the date of grant using the Black‑Scholes option‑pricing model. Expected volatility for the Company’s common stock is determined based on an average of the historical volatility of the Company and the historical volatility of a peer‑group of similar public companies. The expected term of options granted to employees is calculated using the simplified method, which represents the average of the contractual term of the option and the weighted-average vesting period of the option. The expected term of purchase rights for the ESPP is based on the duration of an offering period. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. The risk‑free interest rate is based upon the U.S. Treasury yield curve commensurate with the expected term at the time of grant or remeasurement. Forfeitures are recognized as they occur.

The Company classifies equity-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial reporting and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

Uncertain tax positions represent tax positions for which reserves have been established. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to be recognized in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for

income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Net Loss Per Share

Basic net loss per share is computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed using the sum of the weighted-average number of shares of common stock outstanding during the period and if dilutive, the weighted-average number of potential shares of common stock, including unvested restricted common stock, outstanding stock options and potential shares issuable under the ESPP.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company operates in one operating segment: discovery and development of synthetic biology therapeutics for the treatment of rare, infectious and other diseases. The Company’s chief executive officer, as chief operating decision maker, manages and allocates resources to the operations of the Company on a total company basis. All of the Company’s equipment, leasehold improvements and other fixed assets are physically located within the United States, and all agreements with its partners are denominated in U.S. dollars, except where noted.

New Accounting Pronouncements

New accounting pronouncements are issued by the FASB from time to time, and rules are issued by the SEC that the Company has or will adopt as of a specified date. Unless otherwise noted, management does not believe that any recently issued accounting pronouncements issued by the FASB or guidance issued by the SEC had, or is expected to have, a material impact on the Company’s present or future financial statements.

Recently Adopted Accounting Pronouncements

In October 2020, the FASB issued an amendment, ASU 2020-08, Codification Improvements to Subtopic 310-20, Receivables – Nonrefundable Fees and Other Costs, to the guidance in ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. The amendment requires companies to reevaluate whether a callable debt security that has multiple call dates is within the scope of paragraph 310-20-65-2. The amendment shall be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company adopted the new guidance effective on January 1, 2021 which had an immaterial impact on its consolidated financial statements.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13 - Measurement of Credit Losses on Financial Statements. The new standard requires that expected credit losses relating to financial assets measured on an amortized cost basis and available-for-sale debt securities be recorded through an allowance for credit losses. It also limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. In November 2019, the FASB issued ASU 2019-10 – Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, which amended the effective date for certain companies. The standard is effective for public companies eligible to be smaller reporting companies for annual and interim periods beginning after December 15, 2022. Early adoption is available. The Company does not anticipate a material impact to its net financial position or disclosures as a result of adoption of ASU 2016-13.

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 16,438	$ 32,507
Restricted cash	1,097	1,097
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows	$ 17,535	$ 33,604	$ 27,281

Leases (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Components of Lease Cost for Operating Leases

The components of lease cost for operating leases for the years ended December 31, 2021 and 2020 were (in thousands):

	For the year ended December 31,
Operating leases	2021		2020
Operating lease cost	$	3,824	$	3,628
Variable lease cost		1,500		1,055
Total lease cost	$	5,324	$	4,683

Summary of Weighted Average Remaining Lease Term and Weighted Average Discount Rate for Operating Leases

The weighted average remaining lease term and the weighted average discount rate for operating leases were:

	For the year ended December 31,
	2021			2020
Weighted average discount rate		8.0	%		8.0	%
Weighted average remaining lease term (years)		6.3			7.2

Summary of Maturity of Lease Liabilities for Operating Leases

The following table reconciles the undiscounted cash flows for the operating leases at December 31, 2021 to the operating lease liabilities recorded on the balance sheet: December 31, 2021

Maturity of lease liabilities	Operating Leases
	(in thousands)
2022	$	4,691
2023		3,574
2024		3,681
2025		3,791
2026		3,905
Thereafter		6,689
Total lease payments		26,331
Less: imputed interest		5,768
Total lease liabilities	$	20,563
Current lease liabilities		3,191
Long-term lease liabilities		17,372

Available-for-Sale Securities

12 Months Ended

Dec. 31, 2021

Investments Debt And Equity Securities [Abstract]

Available-for-Sale Securities

(4)	Available-for-Sale Securities

The following tables summarize the available-for-sale securities held at December 31, 2021 and 2020 (in thousands):

December 31, 2021	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Commercial paper	$	106,298	$	8	$	(29	)	$	106,277
Corporate debt securities		5,876		—		(3	)		5,873
U.S. government agency securities and treasuries		8,062		—		(21	)		8,041
Total	$	120,236	$	8	$	(53	)	$	120,191

December 31, 2020	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Commercial paper	$	40,467	$	11	$	(1	)	$	40,477
Corporate debt securities		18,634		4		(1	)		18,637
U.S. government agency securities and treasuries		8,822		1		—			8,823
Total	$	67,923	$	16	$	(2	)	$	67,937

The contractual maturity of all securities held at December 31, 2021 was fifteen months or less. There were twenty investments in an unrealized loss position at December 31, 2021, none of which had been in an unrealized loss position for more than twelve months. The aggregate fair value of the securities in an unrealized loss position at December 31, 2021 and 2020 was $72.2 million and $20.1 million, respectively. The Company reviews its investments for other-than-temporary impairment whenever the fair value of an investment is less than amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers whether it has the ability and intent to hold the investment until maturity or a market price recovery and considers whether evidence indicating the cost of the investment is recoverable outweighs evidence to the contrary. The Company did not hold any securities with an other-than-temporary impairment at December 31, 2021.

Gross realized gains and losses on the sales of investments have not been material to the Company’s consolidated statement of operations.

Common Stock - Additional Information (Detail)	1 Months Ended				9 Months Ended	12 Months Ended	169 Months Ended
Common Stock - Additional Information (Detail)	Sep. 30, 2021 USD ($) $ / shares shares	Jul. 31, 2021 USD ($)	Apr. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2021 shares	Dec. 31, 2021 USD ($) Vote shares	Dec. 31, 2021 USD ($) shares
Class Of Stock [Line Items]
Number of votes entitled to each share of common stock \| Vote						1
Cash dividends \| $							$ 0
Proceeds from issuance of common stock, net of issuance costs \| $						$ 81,042,000
Underwritten Public Offering
Class Of Stock [Line Items]
Sale of common stock, shares \| shares	17,250,000		11,500,000
Proceeds from issuance of common stock, net of issuance costs \| $	$ 48,400,000		$ 32,600,000
Sale of stock, price per share \| $ / shares	$ 3.00		$ 3.00
Common Stock
Class Of Stock [Line Items]
Sale of common stock, shares \| shares						28,750,000
Ginkgo Bioworks, Inc.
Class Of Stock [Line Items]
Sale of stock, price per share \| $ / shares				$ 9.00
Proceeds, net of issuance costs, from issuance of common stock and pre-funded warrants \| $				$ 79,900,000
Proceeds from issuance of common stock, net of issuance costs \| $				$ 57,000,000.0
Ginkgo Bioworks, Inc. \| Common Stock
Class Of Stock [Line Items]
Sale of common stock, shares \| shares				6,340,771
Ginkgo Bioworks, Inc. \| Pre-Funded Warrants
Class Of Stock [Line Items]
Warrants to purchase shares of common stock \| shares				2,548,117
Warrants exercise price per share \| $ / shares				$ 9.00
Warrants exercise price per share paid at closing of offering \| $ / shares				$ 8.99
Proceeds from sale of pre-funded warrants, net of issuance costs \| $				$ 22,900,000
Warrants exercised \| shares					0	0	0
Ginkgo Bioworks, Inc. \| Pre-Funded Warrants \| Maximum
Class Of Stock [Line Items]
Warrants to purchase shares of common stock \| shares				2,548,117
Unbeneficial percentage of ownership after exercise of common stock outstanding effect to issuance				19.99%
Cowen and Company, LLC \| ATM
Class Of Stock [Line Items]
Sale of common stock, shares \| shares					0	2,447,211
Proceeds from issuance of common stock, net of issuance costs \| $						$ 8,000,000.0
Jefferies, LLC \| ATM
Class Of Stock [Line Items]
Sale of common stock, shares \| shares						0
Proceeds from issuance of common stock, net of issuance costs \| $		$ 50,000,000.0

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	At-the-market Offering	Common Stock $0.001 Par Value	Common Stock $0.001 Par Value At-the-market Offering	Additional Paid-in Capital	Additional Paid-in Capital At-the-market Offering	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2019	$ 156,905		$ 33		$ 327,900		$ 110	$ (171,138)
Balance (in Shares) at Dec. 31, 2019			32,266,814
Proceeds from issuance of common stock, net of issuance costs		$ 13,534		$ 5		$ 13,529
Proceeds from issuance of common stock, net of issuance costs, Shares				5,866,258
Exercise of options	16				16
Exercise of options, shares			9,472
Issuance of restricted stock, shares			226,335
Issuance of common stock under employee stock purchase plan	42				42
Issuance of common stock under employee stock purchase plan, Shares			29,857
Cancellation of restricted stock			(215,463)
Equity-based compensation expense	3,907				3,907
Unrealized gain (loss) on securities	(96)						(96)
Net loss	(59,173)							(59,173)
Balance at Dec. 31, 2020	115,135		$ 38		345,394		14	(230,311)
Balance (in Shares) at Dec. 31, 2020			38,183,273
Proceeds from issuance of common stock, net of issuance costs	81,039	$ 8,050	$ 29	$ 3	81,010	$ 8,047
Proceeds from issuance of common stock, net of issuance costs, Shares			28,750,000	2,447,211
Exercise of options	280				280
Exercise of options, shares			139,772
Issuance of restricted stock, shares			242,454
Issuance of common stock under employee stock purchase plan	94				94
Issuance of common stock under employee stock purchase plan, Shares			42,653
Share withholding	(73)				(73)
Share withholding, shares			(28,725)
Cancellation of restricted stock			(77,794)
Equity-based compensation expense	3,361				3,361
Unrealized gain (loss) on securities	(59)						(59)
Net loss	(60,561)							(60,561)
Balance at Dec. 31, 2021	$ 147,266		$ 70		$ 438,113		$ (45)	$ (290,872)
Balance (in Shares) at Dec. 31, 2021			69,698,844

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Temporary Differences Between Basis of Deferred Tax Assets and Liabilities

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. Deferred tax assets consist of the following (in thousands):

	December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	76,802		$	61,181
Tax credit carryforwards		7,248			5,748
Accrued expenses		181			126
Property and equipment		591			279
Lease liabilities		5,618			6,230
Equity compensation		2,396			2,200
Amortizable intangibles		1,197			1,195
Other		238			74
Gross deferred tax assets		94,271			77,033
Deferred tax liabilities:
Right of use assets		(3,794	)		(4,242	)
Gross deferred tax liabilities		(3,794	)		(4,242	)
Valuation allowance		(90,477	)		(72,791	)
Net deferred tax assets	$	—		$	—

Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Income Tax Rate

A reconciliation of the statutory federal income tax rate to the Company’s effective income tax rate is as follows:

	Years ended December 31,
	2021			2020
	Tax Rate			Tax Rate
U.S. federal statutory rate		21	%		21	%
State income taxes, net of federal benefit		6	%		6	%
Other permanent differences		0	%		(1	)%
Tax credits		2	%		2	%
Other items		0	%		4	%
Net change in valuation allowance		(29	)%		(32	)%
Effective income tax rate		—			—

Schedule of Valuation Allowance

A roll-forward of the valuation allowance for the years ended December 31, 2021 and 2020 is as follows (in thousands):

	Years ended December 31,
	2021			2020
Balance at beginning of year	$	(72,791	)	$	(53,834	)
Increase in valuation allowance		(17,686	)		(18,957	)
Balance at end of year	$	(90,477	)	$	(72,791	)

Equity-based Compensation and Equity Incentive Plans - Schedule of Equity-based Compensation Expenses by Award Type (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 3,361,000	$ 3,907,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	58,000	27,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	2,969,000	3,200,000
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 334,000	$ 680,000

Available-for-Sale Securities (Tables)

12 Months Ended

Dec. 31, 2021

Investments Debt And Equity Securities [Abstract]

Summary of Available-for-Sale Securities Held

The following tables summarize the available-for-sale securities held at December 31, 2021 and 2020 (in thousands):

December 31, 2021	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Commercial paper	$	106,298	$	8	$	(29	)	$	106,277
Corporate debt securities		5,876		—		(3	)		5,873
U.S. government agency securities and treasuries		8,062		—		(21	)		8,041
Total	$	120,236	$	8	$	(53	)	$	120,191

December 31, 2020	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Commercial paper	$	40,467	$	11	$	(1	)	$	40,477
Corporate debt securities		18,634		4		(1	)		18,637
U.S. government agency securities and treasuries		8,822		1		—			8,823
Total	$	67,923	$	16	$	(2	)	$	67,937

Subsequent Events

12 Months Ended

Dec. 31, 2021

Subsequent Events [Abstract]

Subsequent Events

(17)Subsequent Events

On January 21, 2022, the Company entered into two Statements of Work with Azzur. Pursuant to the first of the SOWs (the Third SOW), the Company has agreed to pay Azzur $650,000 to renovate and upgrade the Azzur Suite for the Company’s expanded use. The second of the SOWs (the Fourth SOW) replaces the Second SOW that the Company entered into with Azzur on April 29, 2021. Pursuant to the Second SOW, the Company was granted access to, and use of, the Azzur Suite for a period of 20 months, from May 2021 to December 2022. The Fourth SOW extends the Second Term, for the period beginning January 2022 through March 2023 (the Third Term). The total estimated project cost during the Third Term for access to, and use of, the renovated and upgraded Azzur Suite, and the personnel support and other services, is $2.4 million.

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 19,714	$ 19,025
Less accumulated depreciation	(10,626)	(8,249)
Property and equipment, net	9,088	10,776
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,274	7,793
Computer and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	756	769
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	500	421
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,561	9,514
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 623	$ 528

Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents maturity		three months or less
Cash equivalents		$ 16,400,000	$ 32,500,000
Transfers of assets and liabilities between Level 1, Level 2, or Level 3		0	0
Impairment charge		$ 0
Lessee, operating lease, existence of option to extend	true	true
Lessee, operating lease, option to extend		options to extend the lease when it is reasonably certain that option will be exercised
Revenue, practical expedient, incremental cost of obtaining contract [true/false]		true
Revenue, practical expedient, remaining performance obligation, description		The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer
Description of tax benefit likely to be realized upon settlement		greater than 50%
Number of operating segment \| Segment		1
ASU 2017-08
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2021
Change in accounting principle, accounting standards update, immaterial effect [true false]		true
Letter of Credit
Summary Of Significant Accounting Policies [Line Items]
Cash		$ 1,100,000	$ 1,100,000

Leases

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Leases

(13)

Leases

Operating Leases

In July 2017, the Company entered into an agreement to lease approximately 41,346 square feet of laboratory and office space at 301 Binney Street in Cambridge, Massachusetts. Annual rent is approximately $3.4 million. The ten-year lease commenced in January 2018 and contains provisions for a free-rent period, annual rent increases and an allowance for tenant improvements. The Company is responsible for real estate taxes, maintenance, and other operating expenses applicable to the leased premises. The Company has paid for tenant improvements of approximately $2.9 million. Additionally, the Company has capitalized approximately $6.6 million of landlord-funded tenant improvements. The Company was deemed to be the accounting owner of the tenant improvements primarily because it was responsible for project cost overruns, and as such, the amounts were recorded as a leasehold improvement. The landlord-funded tenant improvement allowance is being amortized as a reduction to lease expense ratably over the lease term. In conjunction with the lease, the Company established a letter of credit of approximately $1.0 million secured by cash balances included in restricted cash. Variable payments based on our portion of the operating expenses, including real estate taxes and insurance, are recorded as a period expense when incurred. The Company has an option to extend the term by five years and an option to terminate the agreement if a similar agreement is executed with the landlord or an affiliate of the landlord. Neither option is reasonably certain of exercise and both are excluded from the lease liability calculation.

During the year ended December 31, 2018, the Company entered into an agreement (the First SOW) with Azzur Group, LLC (Azzur) whereby Azzur agreed to provide the Company with access to, and the use of, an approximately 700 square foot cleanroom space to be constructed in Waltham, Massachusetts (the Azzur Suite), for a period of 44 months, from May 1, 2019 to December 31, 2022 (the Initial Term). In April 2021, Synlogic entered into a new agreement (the Second SOW) with Azzur which replaced the First SOW. Pursuant to the Second SOW, Synlogic was granted access to, and use of, the Azzur Suite for a period of 20 months, from May 2021 to December 2022 (the Second Term). The Company determined that the agreement contained an embedded lease because the Company controls the use of the Azzur Suite. Accordingly, the fixed and in-substance fixed consideration under the agreement was used to remeasure the ROU asset and lease liability at the effective date of the Second SOW.

Leases classified as operating leases are included in operating lease ROU assets, current operating lease liabilities and noncurrent operating lease liabilities in our consolidated balance sheets. The operating lease right-of-use asset and operating lease liability represents the Binney Street lease and the Azzur Suite lease. Cash paid for amounts included in the present value of operating lease liabilities was $4.4 and $3.9 million during the years ended December 31, 2021 and 2020, respectively, which is included in operating cash flows.

The components of lease cost for operating leases for the years ended December 31, 2021 and 2020 were (in thousands):

	For the year ended December 31,
Operating leases	2021		2020
Operating lease cost	$	3,824	$	3,628
Variable lease cost		1,500		1,055
Total lease cost	$	5,324	$	4,683

The right-of-use asset for the operating lease is disclosed on the consolidated balance sheets.

The weighted average remaining lease term and the weighted average discount rate for operating leases were:

	For the year ended December 31,
	2021			2020
Weighted average discount rate		8.0	%		8.0	%
Weighted average remaining lease term (years)		6.3			7.2

The following table reconciles the undiscounted cash flows for the operating leases at December 31, 2021 to the operating lease liabilities recorded on the balance sheet: December 31, 2021

Maturity of lease liabilities	Operating Leases
	(in thousands)
2022	$	4,691
2023		3,574
2024		3,681
2025		3,791
2026		3,905
Thereafter		6,689
Total lease payments		26,331
Less: imputed interest		5,768
Total lease liabilities	$	20,563
Current lease liabilities		3,191
Long-term lease liabilities		17,372

The lease cost for finance leases during the years ended December 31, 2021 and 2020, and the finance lease liability at December 31, 2021, were not material.

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Income tax benefits for the net operating losses	$ 0	$ 0
Valuation allowance	$ 90,477,000	72,791,000	$ 53,834,000
Description of tax benefit likely to be realized upon settlement	greater than 50%
Unrecognized tax benefits	$ 0
Interest or penalties accrued	$ 0	0
Income tax examination description	In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending tax examinations. Tax years from 2018 to the present are open to examination under the statute.
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 284,300,000	227,000,000.0
Net operating loss carryforwards subject to expiration	79,400,000
Net operating loss carryforwards not subject to expiration	204,900,000
Federal \| Research and Development.
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 4,500,000
Federal \| Minimum [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards expiration year	2034
Federal \| Maximum
Income Tax Disclosure [Line Items]
Net operating loss carryforwards expiration year	2037
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 270,700,000	$ 213,600,000
Net operating loss carryforwards expiration year	2029
State \| Research and Development.
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 2,900,000

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

(3)	Fair Value of Financial Instruments

The tables below present information about the Company’s assets that are measured at fair value on a recurring basis as of December 31, 2021 and 2020 and indicate the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value, as described under Note 2, Summary of Significant Accounting Policies.

The Company’s investment portfolio includes many fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company applied other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare evaluations. In addition, model processes were used to assess interest rate impact and develop prepayment scenarios. These models take into consideration relevant credit information, perceived market movements, sector news and economic events. The inputs into these models may include benchmark yields, reported trades, broker-dealer quotes, issuer spreads and other relevant data.

At December 31, 2021 and 2020, the Company has classified assets measured at fair value on a recurring basis as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	2021		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	16,437	$	16,437	$	—	$	—
Commercial paper		106,277		—		106,277		—
Corporate debt securities		5,873		—		5,873		—
U.S. government agency securities and treasuries		8,041		8,041		—		—
Total	$	136,628	$	24,478	$	112,150	$	—

	Fair Value Measurements at Reporting Date Using
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	2020		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	32,506	$	32,506	$	—	$	—
Commercial paper		40,477		—		40,477		—
Corporate debt securities		18,637		—		18,637		—
U.S. government agency securities and treasuries		8,823		8,823		—		—
Total	$	100,443	$	41,329	$	59,114	$	—

Cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses at December 31, 2021 and December 31, 2020 are carried at amounts that approximate fair value due to their short-term maturities. Finance lease obligations at December 31, 2021 and December 31, 2020 approximate fair value as they bear interest at a rate approximating a market interest rate.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash

	December 31,		December 31,
	2021		2020
Cash and cash equivalents	$	16,438	$	32,507
Restricted cash		1,097		1,097
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows	$	17,535	$	33,604

Schedule of Useful Life of Property and Equipment

Depreciation begins at the time the asset is placed in service. Depreciation is provided over the following estimated useful lives:

Asset classification		Useful life
Computer and office equipment		3 years
Furniture and fixtures		5 years
Laboratory equipment		5 years
Leasehold improvements		Lesser of useful life or remaining lease term

Equity-based Compensation and Equity Incentive Plans - Schedule of Restricted Common Stock Activity (Detail) - Restricted Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Beginning balance, Number of unvested shares/units	478,207
Granted, Number of shares/units	242,454	226,335
Vested, Number of shares/units	(343,619)
Forfeited, Number of shares/units	(77,794)
Ending balance, Number of unvested shares/units	299,248	478,207
Beginning balance, Unvested Grant date fair value	$ 2.19
Granted, Grant date fair value	3.50
Vested, Grant date fair value	2.39
Forfeited, Grant date fair value	2.96
Ending balance, Unvested Grant date fair value	$ 2.83	$ 2.19

Common Stock (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

The Company has reserved for future issuance the following shares of common stock related to the potential exercise of Pre-Funded Warrants, exercise of stock options, and the employee stock purchase plan:

	December 31, 2021
Common stock issuable under pre-funded warrants		2,548,117
Options exercisable to purchase common stock		2,032,515
Employee Stock Purchase Plan		21,569
Total		4,602,201

Equity-based Compensation and Equity Incentive Plans - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 01, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per share of options granted to employees		$ 2.42	$ 1.27
Total fair value of awards vested		$ 2,800,000	$ 3,400,000
Employee unrecognized compensation expense		$ 5,200,000
Employee unrecognized compensation cost, period of recognition		2 years 7 months 6 days
Equity-based compensation expense		$ 3,361,000	3,907,000
Restricted Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of awards vested		800,000	$ 300,000
Employee unrecognized compensation expense		$ 700,000
Employee unrecognized compensation cost, period of recognition		3 years
Granted		242,454	226,335
Equity-based compensation expense		$ 334,000	$ 680,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock under employee stock purchase plan, Shares		42,653	29,857
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares available for issuance (in shares)	381,832
Percentage of discount for employees under ESPP		15.00%
Purchase price as a percentage of fair value under ESPP		85.00%
Equity-based compensation expense		$ 58,000	$ 27,000
ESPP \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock under employee stock purchase plan, Shares		42,653
Plan 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares outstanding				5.00%
Increase in number of shares available for issuance (in shares)	1,909,163

Common Stock

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Common Stock

(8)	Common Stock

The Company’s common stock has the following characteristics:

•

The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders.

•

The holders of shares of common stock are entitled to receive dividends, if and when, declared by the Company’s board of directors. Since inception, no cash dividends have been declared.

In June 2019, the Company issued to Ginkgo Bioworks, Inc. (Ginkgo) 6,340,771 shares of common stock and accompanying Pre-Funded Warrants (the Pre-Funded Warrants) to purchase up to an aggregate of 2,548,117 shares of common stock, at a combined purchase price per share and Pre-Funded Warrant of $9.00. The Pre-Funded Warrants have an exercise price of $9.00 per share, with $8.99 of such exercise price paid at the closing of the offering. The proceeds, net of issuance costs, were approximately $79.9 million, $57.0 million related to the proceeds from sale of the common stock and $22.9 million related to the proceeds from sale of the Pre-Funded Warrants. The Pre-Funded Warrants may be exercised at any time until all of the Pre-Funded Warrants are exercised in full to the extent that, after giving effect to such issuance after exercise, Ginkgo would not beneficially own in excess of 19.99% of the number of shares of common stock outstanding immediately after giving effect to the issuance. The Pre-Funded Warrants were classified as a component of permanent equity and were recorded at the issuance date using a relative fair value allocation method. The Pre-Funded Warrants are equity classified because they are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, and permit the holders to receive a fixed number of common shares upon exercise. In addition, such warrants do not provide any guarantee of value or return. In addition, in connection with the issuance to Ginkgo of common stock and Pre-Funded Warrants, the Company expanded its existing collaboration and entered into an agreement with Ginkgo for the research and development of engineered microbial therapeutic products. None of the Pre-Funded Warrants have been exercised as of December 31, 2021. (See Note 10, Collaboration Agreements: Ginkgo Collaboration).

On October 13, 2017, the Company entered into a sales agreement with Cowen and Company, LLC (Cowen) with respect to an at-the-market (ATM) offering program. In an ATM offering, exchange-listed companies incrementally sell newly issued shares into the secondary trading market through a designated broker-dealer at prevailing market prices. During the year ended December 31, 2021, 2,447,211 shares of common stock were sold pursuant to the ATM, resulting in net proceeds of approximately $8.0 million. There were no sales pursuant to the Cowen ATM subsequent to March 31, 2021.

In July 2021, the Company entered into a new sales agreement with Jefferies, LLC (Jefferies) with respect to an ATM, under which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock having aggregate sales proceeds of up to $50.0 million. Jefferies is not required to sell any specific amount but acts as the Company’s sales agent using commercially reasonable efforts consistent with its normal trading and sales practices. During the year ended December 31, 2021, no shares of common stock were sold pursuant to the sales agreement with Jefferies.

In April 2021, the Company sold 11,500,000 shares of its common stock at a public offering price of $3.00 per share pursuant to an underwritten public offering. The net proceeds to the Company from the offering, after deducting the underwriting discounts and commissions and offering expenses payable by the Company, were approximately $32.6 million. All shares of common stock sold in the offering were sold by the Company.

In September 2021, the Company sold 17,250,000 shares of its common stock at a public offering price of $3.00 per share pursuant to an underwritten public offering. The net proceeds to the Company from the offering, after deducting the underwriting discounts and commissions and offering expenses payable by the Company, were approximately $48.4 million. All shares of common stock sold in the offering were sold by the Company.

	December 31, 2021
Common stock issuable under pre-funded warrants		2,548,117
Options exercisable to purchase common stock		2,032,515
Employee Stock Purchase Plan		21,569
Total		4,602,201

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section 50
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-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/topic&trid=2208762

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496180-112644

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 13
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Net Loss per Share

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss per Share

(11)	Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share (in thousands, except for share and per share amounts):

	2021			2020
Numerator:
Net loss	$	(60,561	)	$	(59,173	)
Denominator:
Weighted-average common shares outstanding - basic and diluted		55,329,711			35,835,744
Net loss per share - basic and diluted	$	(1.09	)	$	(1.65	)

The Company’s potentially dilutive shares, which include outstanding stock options, unvested restricted common stock and potential shares issuable under the ESPP, are considered to be common share equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of the diluted net loss per share attributable to common stockholders for the period indicated because including them would have had an anti-dilutive effect.

	As of December 31,
	2021		2020
Unvested restricted common stock awards		299,248		478,207
Outstanding options to purchase common stock		4,500,913		3,343,836
Potential shares issuable under the ESPP		21,569		12,037

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2021

Text Block [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):

	December 31,		December 31,
	2021		2020
Prepaid insurance	$	979	$	856
Prepaid research and development		2,721		4,771
Other prepaid expenses		710		528
Other current assets		311		247
Total prepaid expenses and other current assets	$	4,721	$	6,402

Property and Equipment, Net

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Property and Equipment, Net

(6)	Property and Equipment, net

Property and equipment, net consists of the following (in thousands):

	December 31,			December 31,
	2021			2020
Laboratory equipment	$	8,274		$	7,793
Computer and office equipment		756			769
Furniture and fixtures		500			421
Leasehold improvements		9,561			9,514
Construction in progress		623			528
		19,714			19,025
Less accumulated depreciation		(10,626	)		(8,249	)
Property and equipment, net	$	9,088		$	10,776

Depreciation expense on property and equipment was $2.4 million and $2.6 million in 2021 and 2020, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Accrued Expenses

(7)	Accrued Expenses

Accrued expenses consist of the following (in thousands):

	December 31,		December 31,
	2021		2020
Payroll related	$	3,495	$	3,005
Professional fees		298		215
Research and development		336		230
Other		273		323
Total accrued expenses	$	4,402	$	3,773

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 16,438	$ 32,507
Short-term marketable securities	112,150	67,937
Prepaid expenses and other current assets	4,721	6,402
Total current assets	133,309	106,846
Long-term marketable securities	8,041
Property and equipment, net	9,088	10,776
Right of use asset - operating lease	13,889	15,527
Restricted cash	1,097	1,097
Prepaid research and development, net of current portion	9,309	9,590
Other assets	3	4
Total assets	174,736	143,840
Current liabilities:
Accounts payable	1,944	1,995
Accrued expenses	4,402	3,773
Deferred revenue	531
Lease liability - operating lease	3,191	2,531
Finance lease obligations	12	2
Total current liabilities	10,080	8,301
Long-term liabilities:
Lease liability - operating lease, net of current portion	17,372	20,273
Finance lease obligations, net of current portion	18
Other long-term liabilities		131
Total long-term liabilities	17,390	20,404
Commitments and contingencies (Note 14)
Stockholders' equity
Common stock, $0.001 par value 250,000,000 shares authorized as of December 31, 2021 and December 31, 2020. 69,698,844 shares issued and outstanding as of December 31, 2021 and 38,183,273 shares issued and outstanding as of December 31, 2020.	70	38
Additional paid-in capital	438,113	345,394
Accumulated other comprehensive income (loss)	(45)	14
Accumulated deficit	(290,872)	(230,311)
Total stockholders' equity	147,266	115,135
Total liabilities and stockholders' equity	$ 174,736	$ 143,840

Equity-based Compensation and Equity Incentive Plans - Schedule of Stock Option Activity Under 2015 and 2017 Plan (Parenthetical) (Detail) - shares	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price And Additional Disclosures [Abstract]
Number of options in money	1,210,026	970,826

Equity-based Compensation and Equity Incentive Plans - Schedule of Equity-based Compensation Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 3,361	$ 3,907
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	1,373	1,724
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 1,988	$ 2,183

Income Taxes - Schedule of Temporary Differences Between Basis of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 76,802	$ 61,181
Tax credit carryforwards	7,248	5,748
Accrued expenses	181	126
Property and equipment	591	279
Lease liabilities	5,618	6,230
Equity compensation	2,396	2,200
Amortizable intangibles	1,197	1,195
Other	238	74
Gross deferred tax assets	94,271	77,033
Deferred tax liabilities:
Right of use assets	(3,794)	(4,242)
Gross deferred tax liabilities	(3,794)	(4,242)
Valuation allowance	$ (90,477)	$ (72,791)	$ (53,834)

Leases - Components of Lease Cost for Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating leases
Operating lease cost	$ 3,824	$ 3,628
Variable lease cost	1,500	1,055
Operating and variable lease cost	$ 5,324	$ 4,683

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, authorized	250,000,000	250,000,000
Common stock, Issued	69,698,844	38,183,273
Common stock, outstanding	69,698,844	38,183,273

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Revenue	$ 1,754	$ 545
Operating expenses:
Research and development	47,127	47,474
General and administrative	15,392	13,537
Total operating expenses	62,519	61,011
Loss from operations	(60,765)	(60,466)
Other income (expense):
Interest and investment income	210	1,302
Interest expense	(2)	(6)
Other expense	(4)	(3)
Other income (expense), net	204	1,293
Net loss	$ (60,561)	$ (59,173)
Net loss per share - basic and diluted	$ (1.09)	$ (1.65)
Weighted-average common stock outstanding - basic and diluted	55,329,711	35,835,744
Comprehensive loss:
Net loss	$ (60,561)	$ (59,173)
Net unrealized loss on marketable securities	(59)	(96)
Comprehensive loss	$ (60,620)	$ (59,269)

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

(12)	Income Taxes

During the years ended December 31, 2021 and 2020, the Company recorded no income tax benefits for the net operating losses incurred due to its uncertainty of reclaiming a benefit for those losses.

	December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	76,802		$	61,181
Tax credit carryforwards		7,248			5,748
Accrued expenses		181			126
Property and equipment		591			279
Lease liabilities		5,618			6,230
Equity compensation		2,396			2,200
Amortizable intangibles		1,197			1,195
Other		238			74
Gross deferred tax assets		94,271			77,033
Deferred tax liabilities:
Right of use assets		(3,794	)		(4,242	)
Gross deferred tax liabilities		(3,794	)		(4,242	)
Valuation allowance		(90,477	)		(72,791	)
Net deferred tax assets	$	—		$	—

Management of the Company has evaluated the positive and negative evidence bearing upon the realizability of the Company’s deferred tax assets, which are comprised principally of net operating loss carryforwards, and determined that it is more likely than not that the Company will not recognize the benefits of the deferred tax assets. As a result, a full valuation allowance of approximately $90.5 million and $72.8 million was established at December 31, 2021 and 2020, respectively.

A reconciliation of the statutory federal income tax rate to the Company’s effective income tax rate is as follows:

	Years ended December 31,
	2021			2020
	Tax Rate			Tax Rate
U.S. federal statutory rate		21	%		21	%
State income taxes, net of federal benefit		6	%		6	%
Other permanent differences		0	%		(1	)%
Tax credits		2	%		2	%
Other items		0	%		4	%
Net change in valuation allowance		(29	)%		(32	)%
Effective income tax rate		—			—

A roll-forward of the valuation allowance for the years ended December 31, 2021 and 2020 is as follows (in thousands):

	Years ended December 31,
	2021			2020
Balance at beginning of year	$	(72,791	)	$	(53,834	)
Increase in valuation allowance		(17,686	)		(18,957	)
Balance at end of year	$	(90,477	)	$	(72,791	)

As of December 31, 2021 and 2020, the Company had federal net operating loss carryforwards that may be available to reduce future taxable income of $284.3 million and $227.0 million, respectively. Of the $284.3 million of federal net operating loss carryforwards, $79.4 million will expire on various dates from 2034 to 2037. The remaining $204.9 million of federal net operating loss carryforwards do not expire. The Company also had state net operating loss carryforwards that may be available to reduce future taxable income of $270.7 million and $213.6 million, for the periods ended December 31, 2021 and 2020, respectively. The state net operating loss carryforwards begin to expire in 2029. In addition, at December 31, 2021, the Company had federal and state research and development tax credit carryforwards available to reduce future tax liabilities of $4.5 million and $2.9 million, respectively.

Pursuant to Section 382 of the Internal Revenue Code of 1986 (IRC), certain substantial changes in the Company’s ownership may result in a limitation on the amount of net operating loss (NOL) carryforwards and research and development credit (R&D credit) carryforwards that may be used in future years. Utilization of the NOL and R&D credit carryforwards may be subject to a substantial annual limitation under Section 382 of the IRC due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized annually to offset future taxable income and tax. The Company has not completed a study to assess whether an ownership change has occurred, or whether there have been multiple ownership changes since its formation, due to the significant complexity and related costs associated with such a study. There could be additional ownership changes in the future that may result in additional limitations on the utilization of NOL carryforwards and credits.

The Company is required to determine whether a tax position of the Company is more likely than not to be sustained upon examination, including resolution of any related appeals of litigation processes, based on the technical merits of the position. For tax positions meeting the more likely than not threshold, the tax amount recognized in the financial statements is reduced by the largest benefit that has a greater than fifty percent likelihood of being realized upon the ultimate settlement with the relevant taxing authority. The Company has not recognized any liability for unrecognized tax benefits as of December 31, 2021. The Company’s policy is to record interest and penalties related to unrecognized tax benefits on the income tax expense line in the consolidated statement of operations. There are no interest or penalties accrued at December 31, 2021 and 2020.

The Company files tax returns, on an entity-level basis, as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending tax examinations. Tax years from 2018 to the present are open to examination under the statute. The Company’s net operating losses and other attributes generated in a closed tax year may still be adjusted to determine the amount of carryforward deduction available in an open year under examination.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI http://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Available-for-Sale Securities - Additional Information (Detail) $ in Millions	Dec. 31, 2021 USD ($) Investment Security	Dec. 31, 2020 USD ($)
Investments Debt And Equity Securities [Abstract]
Number of investments in unrealized loss position	20
Number of investments in unrealized loss position, more than twelve months	0
Aggregate fair value of securities in unrealized loss position \| $	$ 72.2	$ 20.1
Number of securities with other than temporary impairment \| Security	0

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

(14)	Commitments and Contingencies

In the ordinary course of business, the Company may be subject to legal proceedings, claims and litigation as the Company operates in an industry susceptible to patent legal claims. The Company accounts for estimated losses with respect to legal proceedings and claims when such losses are probable and estimable. Legal costs associated with these matters are expensed when incurred. The Company is not currently a party to any material legal proceedings.

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share (in thousands, except for share and per share amounts):

	2021			2020
Numerator:
Net loss	$	(60,561	)	$	(59,173	)
Denominator:
Weighted-average common shares outstanding - basic and diluted		55,329,711			35,835,744
Net loss per share - basic and diluted	$	(1.09	)	$	(1.65	)

Schedule of Potentially Common Shares Excluded from Calculation of Net Loss Per share

	As of December 31,
	2021		2020
Unvested restricted common stock awards		299,248		478,207
Outstanding options to purchase common stock		4,500,913		3,343,836
Potential shares issuable under the ESPP		21,569		12,037

Summary of Significant Accounting Policies - Schedule of Useful Life of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2021
Computer and Office Equipment
Property Plant And Equipment [Line Items]
Useful life	3 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Useful life	5 years
Laboratory Equipment
Property Plant And Equipment [Line Items]
Useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Useful life	Lesser of useful life or remaining lease term

Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid insurance	$ 979	$ 856
Prepaid research and development	2,721	4,771
Other prepaid expenses	710	528
Other current assets	311	247
Total prepaid expenses and other current assets	$ 4,721	$ 6,402

Common Stock - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2021 shares
Class Of Stock [Line Items]
Total Shares of Common Stock Reserved for Future Issuance	4,602,201
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total Shares of Common Stock Reserved for Future Issuance	21,569
Options Exercisable to Purchase Common Stock
Class Of Stock [Line Items]
Total Shares of Common Stock Reserved for Future Issuance	2,032,515
Common Stock Issuable Under Pre-Funded Warrants
Class Of Stock [Line Items]
Total Shares of Common Stock Reserved for Future Issuance	2,548,117

Employee Benefits

12 Months Ended

Dec. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Employee Benefits

(15)	Employee Benefits

The Company has a defined contribution 401(k) plan for eligible employees. Employees are eligible to participate in the plan beginning on their date of hire. Under the terms of the plan, employees may make voluntary contributions as a percentage of compensation. The Company started to match employee contributions effective January 1, 2019. The Company matched 50% of the employee contributions to the 401(k) plan up to a maximum of 4% of the participating employee’s eligible earnings, resulting in a maximum company match of 2% of the participating employee’s eligible earnings, and subject to certain additional statutory dollar limitations. In 2021, the Company increased the match to 50% of the employee contributions up to a maximum of 6% of the participating employee’s eligible earnings, resulting in a maximum company match of 3% of the participating employee’s eligible earnings, and subject to certain additional statutory dollar limitations. For the years ended December 31, 2021 and 2020, the Company made $276,000 and $229,000 contributions the plan, respectively.

Collaboration Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2021	Jun. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognition of revenue			$ 1,754	$ 545
Deferred revenue			$ 531
Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares sold			28,750,000
Ginkgo Collaboration
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Current pre-paid research and development			$ 1,900
Non-current pre-paid research and development			9,300
Prepayment to related party for collaboration agreement		$ 30,000
Related party transaction collaboration agreement, initial term		5 years
Ginkgo Collaboration \| Pre-Funded Warrants
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrants to purchase shares of common stock		2,548,117
Ginkgo Collaboration \| Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares sold		6,340,771
Maximum \| Ginkgo Collaboration \| Pre-Funded Warrants
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrants to purchase shares of common stock		2,548,117
Roche Collaboration and Option Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront, nonrefundable technology access fee					$ 1,000
Milestones payment upon achievement of certain success criteria					5,000
Upfront payments					$ 1,000
Milestone payments	$ 1,000
Recognition of revenue			1,500
Roche Collaboration and Option Agreement \| Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue			$ 500
Roche Collaboration and Option Agreement \| Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration in research and development			12 months
Roche Collaboration and Option Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration in research and development			18 months
Abb Vie Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognition of revenue				$ 500

Related-Party Transactions

12 Months Ended

Dec. 31, 2021

Related-Party Transactions

(16)	Related-Party Transactions

In June 2019, the Company expanded its collaboration and entered into an agreement with Ginkgo for the research and development of engineered microbial therapeutic products. As of December 31, 2020, Ginkgo owns 6,340,771 shares of the Company’s outstanding common stock. See Note 10, Collaboration Agreements: Ginkgo Collaboration.

Under the agreement the Company made a prepayment to Ginkgo of $30.0 million for its foundry services that will be provided to the Company over an initial term of five years. At December 31, 2021, the Company had remaining balances of $1.9 million and $9.3 million of current and non-current pre-paid research and development costs related to this transaction, respectively. For the year ended December 31, 2021, the Company used $2.4 million of the pre-paid research and development expenses.

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Depreciation expense	$ 2,443	$ 2,636

Equity-based Compensation and Equity Incentive Plans

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity-based Compensation and Equity Incentive Plans

(9)	Equity‑based Compensation and Equity Incentive Plans

Equity Plans

The Company currently has three active equity plans.

The 2015 Equity Incentive Award Plan (2015 Plan) functions as the primary equity plan for the Company. The 2015 Plan includes an “evergreen provision” that allows for an annual increase in the number of shares of common stock available for issuance under the 2015 Plan, which annual increase will be added on the first day of each fiscal year from 2016 through 2025, inclusive, and will be equal to the lesser of (i) five percent of the shares outstanding on the last day of the immediately preceding fiscal year and (ii) such smaller number of shares as determined by the Board of Directors. On January 1, 2021, the Company added 1,909,163 shares to the 2015 Plan pursuant to the “evergreen provision”. The 2015 Plan provides for the granting of a variety of stock‑based compensation awards, including stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, deferred stock awards, dividend equivalent awards, stock payment awards, performance awards and other stock‑based awards.

The 2017 Stock Incentive Plan (the 2017 Plan) provides for the grant of incentive stock options, non-qualified stock options, restricted and unrestricted stock awards and other stock-based awards.

The 2015 Employee Stock Purchase Plan (ESPP) allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP generally provides for set offering periods, and at the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. The Company suspended the ESPP in 2017. In December 2019, the Board reactivated the 2015 ESPP and approved an amendment to the ESPP to (i) reduce the permitted payroll deduction and number of shares of the Company’s common stock that a participant may purchase per calendar year and offering period under the ESPP and (ii) establish a period for enrollment for eligible participants. The reactivation of the 2015 ESPP was effective immediately. The Company’s executive officers are eligible to participate in the 2015 ESPP. The ESPP includes an “evergreen provision,” allowing for an annual increase in the number of shares of common stock available for issuance. On January 1, 2021, the Company added 381,832 shares to the ESPP pursuant to the “evergreen provision”. There were 42,653 shares of common stock purchased under the ESPP during the year ended December 31, 2021.

Stock Options

The weighted average assumptions used in the Black-Scholes option-pricing model for stock options issued to employees and non-employees under the 2015 Plan and the 2017 Plan, during the years ended December 31, 2021 and 2020 were:

	Year ended December 31,
Employees:	2021		2020
Expected term	6.2 years		6.2 years
Weighted-average, risk-free interest rate	1.0%		0.6%
Expected volatility	84.9%		77.2%
Dividend yield		—		—

The following table summarizes stock option activity under the 2015 and 2017 Plans.

	Stock options outstanding
						Weighted
						average
				Weighted		remaining		Aggregate
				average		contractual		intrinsic
	Number of			exercise		term		value^(a)
	options			price		(in years)		(in thousands)
Outstanding at December 31, 2020		3,343,836		$	6.00		8.4	$	399
Granted		2,215,796		$	3.37				—
Exercised		(139,772	)	$	2.24				160
Cancelled/Forfeited		(918,947	)	$	4.30				—
Outstanding at December 31, 2021		4,500,913		$	5.17		8.2	$	588

Vested or expected to vest at December 31, 2021		4,500,913		$	5.17		8.2	$	588
Exercisable at December 31, 2021		2,032,515		$	7.33		7.2	$	258

^(a)

^{The aggregate intrinsic value is calculated as the difference between the exercise price of the options and the fair market value of the underlying common stock for the options that were in the money at December 31, 2021 and 2020. 1,210,026 and 970,826 options were in the money at December 31, 2021 and 2020, respectively.}

The weighted average grant date fair value per share of options granted during the years ended December 31, 2021 and 2020 was approximately $2.42 and $1.27, respectively. The total fair value of awards that vested during the years ended December 31, 2021 and 2020 was $2.8 million and $3.4 million, respectively.

As of December 31, 2021, there was approximately $5.2 million of unrecognized share-based compensation for unvested stock option grants which is expected to be recognized over a weighted average period of 2.6 years. The total unrecognized share-based compensation cost will be adjusted for actual forfeitures as they occur.

Restricted Common Stock

During the years ended December 31, 2021 and 2020, 242,454 and 226,335 shares of restricted common stock were granted, respectively.

The following table shows restricted common stock activity:

	Restricted stock awards
				Weighted average grant date
	Number of			fair value
	shares			(per share)
Unvested at December 31, 2020		478,207		$	2.19
Granted		242,454			3.50
Vested		(343,619	)		2.39
Forfeited		(77,794	)		2.96
Unvested at December 31, 2021		299,248		$	2.83

The total fair value of shares that vested during the years ended December 31, 2021 and 2020 was $0.8 million and $0.3 million, respectively.

As of December 31, 2021, there was approximately $0.7 million of unrecognized share-based compensation related to restricted stock awards granted, which is expected to be recognized over a weighted average period of 3.0 years. The total unrecognized share-based compensation cost will be adjusted for actual forfeitures as they occur.

Employee Stock Purchase Plan

The ESPP is considered a compensatory plan with the related compensation expense recognized over the six-month offering periods. The compensation expense for the years ended December 31, 2021 and December 31, 2020 was $58,000 and $27,000, respectively.

Equity Compensation

The Company has recorded total equity‑based compensation expense of approximately $3.4 million and $3.9 million, during the years ended December 31, 2021 and 2020, respectively. Equity compensation during the years ended December 31, 2021 and 2020 is derived from stock options, restricted stock awards, and the ESPP.

The following table summarizes equity‑based compensation expense within the Company’s consolidated statements of operations and comprehensive loss for the years ended December 31, 2021 and 2020 (in thousands):

	Years ended December 31,
	2021		2020
Research and development	$	1,373	$	1,724
General and administrative		1,988		2,183
	$	3,361	$	3,907

The following table summarizes equity‑based compensation expense by type of award for the years ended December 31, 2021 and 2020 (in thousands):

	Years ended December 31,
	2021		2020
Stock options	$	2,969	$	3,200
Restricted stock awards		334		680
ESPP		58		27
	$	3,361	$	3,907

Available-for-Sale Securities - Summary of Available-for-Sale Securities Held (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 120,236	$ 67,923
Gross unrealized gains	8	16
Gross unrealized losses	(53)	(2)
Fair Value	120,191	67,937
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	106,298	40,467
Gross unrealized gains	8	11
Gross unrealized losses	(29)	(1)
Fair Value	106,277	40,477
Corporate Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	5,876	18,634
Gross unrealized gains		4
Gross unrealized losses	(3)	(1)
Fair Value	5,873	18,637
U.S. Government Agency Securities and Treasuries
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	8,062	8,822
Gross unrealized gains		1
Gross unrealized losses	(21)
Fair Value	$ 8,041	$ 8,823

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following (in thousands):

	December 31,		December 31,
	2021		2020
Payroll related	$	3,495	$	3,005
Professional fees		298		215
Research and development		336		230
Other		273		323
Total accrued expenses	$	4,402	$	3,773

Income Taxes - Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
U.S. federal statutory rate	21.00%	21.00%
State income taxes, net of federal benefit, Tax Rate	6.00%	6.00%
Other permanent differences, Tax Rate	0.00%	(1.00%)
Tax credits, Tax Rate	2.00%	2.00%
Other items, Tax Rate	0.00%	4.00%
Net change in valuation allowance, Tax Rate	(29.00%)	(32.00%)

Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash, cash equivalents, and short-term marketable securities	$ 136,600
Restricted cash	1,097	$ 1,097
Accumulated deficit	$ (290,872)	$ (230,311)

- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

+ References + Details

Leases - Additional Information (Detail)	1 Months Ended		12 Months Ended
Leases - Additional Information (Detail)	Apr. 30, 2021	Jul. 31, 2017 USD ($) ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2018 ft²
Lessee Lease Description [Line Items]
Laboratory and office space to be leased \| ft²		41,346
Operating lease annual rent		$ 3,400,000
Term of lease		10 years
Tenant improvement investment		$ 2,900,000
Letter of credit		$ 1,000,000.0
Lessee, operating lease, existence of option to extend		true	true
Renewal term of lease		5 years
Lessee, operating lease, existence of option to terminate		true
Agreement expiration date					Dec. 31, 2022
Cash paid included in operating cash flows			$ 4,400,000	$ 3,900,000
Master Services Agreement
Lessee Lease Description [Line Items]
Access and use of space under agreement \| ft²					700
Term of agreement					44 months
New Agreement
Lessee Lease Description [Line Items]
Term of agreement	20 months
Agreement expiration date	Dec. 31, 2022
Maximum
Lessee Lease Description [Line Items]
Tenant improvement investment		$ 6,600,000

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2021

Text Block [Abstract]

Prepaid Expenses and Other Current Assets

(5)	Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):

	December 31,		December 31,
	2021		2020
Prepaid insurance	$	979	$	856
Prepaid research and development		2,721		4,771
Other prepaid expenses		710		528
Other current assets		311		247
Total prepaid expenses and other current assets	$	4,721	$	6,402

Subsequent Events - Additional Information (Details) - Subsequent Event - Azzur	Jan. 21, 2022 USD ($)
Subsequent Event [Line Items]
Collaboration agreement description	On January 21, 2022, the Company entered into two Statements of Work with Azzur. Pursuant to the first of the SOWs (the Third SOW), the Company has agreed to pay Azzur $650,000 to renovate and upgrade the Azzur Suite for the Company’s expanded use. The second of the SOWs (the Fourth SOW) replaces the Second SOW that the Company entered into with Azzur on April 29, 2021. Pursuant to the Second SOW, the Company was granted access to, and use of, the Azzur Suite for a period of 20 months, from May 2021 to December 2022. The Fourth SOW extends the Second Term, for the period beginning January 2022 through March 2023 (the Third Term). The total estimated project cost during the Third Term for access to, and use of, the renovated and upgraded Azzur Suite, and the personnel support and other services, is $2.4 million.
First SOW
Subsequent Event [Line Items]
Agreed to pay renovation and upgradation fee	$ 650,000
Fourth SOW
Subsequent Event [Line Items]
Estimated project cost	$ 2,400,000

Equity-based Compensation and Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2021

Schedule of Restricted Common Stock Activity

The following table shows restricted common stock activity:

	Restricted stock awards
				Weighted average grant date
	Number of			fair value
	shares			(per share)
Unvested at December 31, 2020		478,207		$	2.19
Granted		242,454			3.50
Vested		(343,619	)		2.39
Forfeited		(77,794	)		2.96
Unvested at December 31, 2021		299,248		$	2.83

Schedule of Equity-based Compensation Expenses

	Years ended December 31,
	2021		2020
Research and development	$	1,373	$	1,724
General and administrative		1,988		2,183
	$	3,361	$	3,907

Schedule of Equity-based Compensation Expenses by Award Type

The following table summarizes equity‑based compensation expense by type of award for the years ended December 31, 2021 and 2020 (in thousands):

	Years ended December 31,
	2021		2020
Stock options	$	2,969	$	3,200
Restricted stock awards		334		680
ESPP		58		27
	$	3,361	$	3,907

2015 and 2017 Plan

Schedule of Weighted Average Assumption Used Black-Scholes Option-pricing Model for Stock Options Issued to Employees and Non-employees

	Year ended December 31,
Employees:	2021		2020
Expected term	6.2 years		6.2 years
Weighted-average, risk-free interest rate	1.0%		0.6%
Expected volatility	84.9%		77.2%
Dividend yield		—		—

Schedule of Stock Option Activity

The following table summarizes stock option activity under the 2015 and 2017 Plans.

	Stock options outstanding
						Weighted
						average
				Weighted		remaining		Aggregate
				average		contractual		intrinsic
	Number of			exercise		term		value^(a)
	options			price		(in years)		(in thousands)
Outstanding at December 31, 2020		3,343,836		$	6.00		8.4	$	399
Granted		2,215,796		$	3.37				—
Exercised		(139,772	)	$	2.24				160
Cancelled/Forfeited		(918,947	)	$	4.30				—
Outstanding at December 31, 2021		4,500,913		$	5.17		8.2	$	588

Vested or expected to vest at December 31, 2021		4,500,913		$	5.17		8.2	$	588
Exercisable at December 31, 2021		2,032,515		$	7.33		7.2	$	258

^(a)

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Payroll related	$ 3,495	$ 3,005
Professional fees	298	215
Research and development	336	230
Other	273	323
Total accrued expenses	$ 4,402	$ 3,773

Equity-based Compensation and Equity Incentive Plans - Schedule of Stock Option Activity Under 2015 and 2017 Plan (Detail) - 2015 and 2017 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding Beginning balance, Number of options	3,343,836
Granted, Number of options	2,215,796
Exercised, Number of options	(139,772)
Cancelled/Forfeited, Number of options	(918,947)
Outstanding Ending balance, Number of options	4,500,913	3,343,836
Number of options, Vested or expected to vest	4,500,913
Number of options, Exercisable	2,032,515
Beginning balance, Weighted-average price	$ 6.00
Granted, Weighted-average price	3.37
Exercised, Weighted-average price	2.24
Cancelled/Forfeited, Weighted-average price	4.30
Ending balance, Weighted-average price	5.17	$ 6.00
Weighted-average price Vested or expected to vest	5.17
Weighted-average price, Exercisable	$ 7.33
Outstanding, weighted average remaining contractual term (Year)	8 years 2 months 12 days	8 years 4 months 24 days
Weighted average remaining contractual term, Vested or expected to vest	8 years 2 months 12 days
Weighted average remaining contractual term, Exercisable	7 years 2 months 12 days
Beginning balance, Aggregate Intrinsic value	$ 399
Exercised, Aggregate Intrinsic value	160
Ending balance, Aggregate Intrinsic value	588	$ 399
Aggregate Intrinsic value, Vested or expected to vest at December 31, 2021	588
Aggregate Intrinsic value, Exercisable at December 31, 2021	$ 258

Net Loss per Share - Schedule of Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (60,561)	$ (59,173)
Denominator:
Weighted-average common shares outstanding - basic and diluted	55,329,711	35,835,744
Net loss per share - basic and diluted	$ (1.09)	$ (1.65)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Income Taxes - Schedule of Valuation Allowance - (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ (72,791)	$ (53,834)
Increase in valuation allowance	(17,686)	(18,957)
Balance at end of year	$ (90,477)	$ (72,791)

Net Loss per Share - Schedule of Potentially Common Shares Excluded from Calculation of Net Loss Per share (Detail) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Unvested Restricted Common Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Common Shares Excluded from Calculation of Net Loss Per share	299,248	478,207
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Common Shares Excluded from Calculation of Net Loss Per share	4,500,913	3,343,836
Potential Shares Issuable Under ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Common Shares Excluded from Calculation of Net Loss Per share	21,569	12,037

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

(2)	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S.) (U.S. GAAP or GAAP).

Principles of Consolidation

Use of Estimates

Cash Equivalents

Concentration of Credit Risk

Restricted Cash

	December 31,		December 31,
	2021		2020
Cash and cash equivalents	$	16,438	$	32,507
Restricted cash		1,097		1,097
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows	$	17,535	$	33,604

Fair Value

•

Level 1 – Utilize observable inputs such as quoted prices in active markets for identical assets or liabilities;

•

Level 2 – Utilize data points that are either directly or indirectly observable, such as quoted prices, interest rates and yield curves;

•

Level 3 – Utilize unobservable data points in which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability.

Available-for-Sale Securities

Property and Equipment

Depreciation begins at the time the asset is placed in service. Depreciation is provided over the following estimated useful lives:

Asset classification		Useful life
Computer and office equipment		3 years
Furniture and fixtures		5 years
Laboratory equipment		5 years
Leasehold improvements		Lesser of useful life or remaining lease term

Impairment of Long‑Lived Assets

Leases

Research and Development Costs

Revenue recognition

The Company generates revenue through a collaboration and option agreement with Roche for the development and commercialization of product candidates.

Licenses of Intellectual Property

Research and Development Services

Customer Options

Milestone Payments

Royalties

Contract Costs

Equity‑Based Compensation

Income Taxes

income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Net Loss Per Share

Segment Information

New Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Employee Benefits - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Eligible employees to contribute to 401(k) plan	50.00%	50.00%
Employee contribution, percentage	6.00%	4.00%
Maximum matching contributions as a percentage of eligible compensation	3.00%	2.00%
Employee contribution	$ 276,000	$ 229,000

Collaboration Agreements

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration Agreements

(10)	Collaboration Agreements

Roche Collaboration

In June 2021, the Company entered into a Pilot Collaboration and Option Agreement (the Roche Collaboration and Option Agreement) with F. Hoffmann-La Roche Ltd (Roche Basel) and Hoffmann-La Roche Inc. (Roche US, and together with Roche Basel, Roche). Under the terms of the Roche Collaboration and Option Agreement, the Company and Roche will seek to collaborate to research and pre-clinically develop Synthetic Biotic medicines for addressing an undisclosed novel target for the treatment of inflammatory bowel disease (the Product Candidate).

Pursuant to the Roche Collaboration and Option Agreement, Roche agreed to pay the Company, an upfront, nonrefundable technology access fee of $1.0 million, which the Company received in July 2021. In addition, the Company is eligible to receive up to $5.0 million in milestone payments upon the achievement of certain success criteria. Following the research period, Roche holds an exclusive option right (the Option) to negotiate a definitive Collaboration and License Agreement (CLA) for further development and commercialization of the Product Candidate.

Pursuant to the Roche Collaboration and Option Agreement, during the term of such agreement, each party has granted to the other party a non-exclusive, non-transferrable, non-sublicensable, royalty-free right and license to certain intellectual property and know-how controlled by such party, solely as necessary for the party to perform its obligations under the Roche Collaboration and Option Agreement. The parties will establish a Joint Research Committee (JRC) to oversee and manage the execution of the underlying study plan for the Roche Collaboration and Option Agreement.

The Roche Collaboration and Option Agreement includes various representations, warranties, covenants, indemnities, and other customary provisions. Roche may terminate the Roche Collaboration and Option Agreement without cause immediately upon written notice where certain success criteria have been met for parts of the study plan, or upon ninety (90) days’ prior written notice to the Company. Either party may terminate the Roche Collaboration and Option Agreement in the event of an uncured material breach of the other party.

The research and development will be performed by the Company for approximately 12 to 18 months according to three phases of research as defined in the research plan. The Company is eligible to receive milestone payments from Roche upon the achievement of success criteria for respective milestones.

The Company assessed this arrangement in accordance with ASC 606, Revenue from Contracts with Customers, and concluded that the contract counterparty, Roche, is a customer. The Company identified the following material promises made by the Company to Roche at the outset of the arrangement: (1) a non-exclusive royalty-free research and development license; (2) research and development services for pre-clinical activities under the research plan; (3) implicit renewal options created by Roche’s decision not to terminate the contract; (4) the Company’s participation on the JRC; and (5) an exclusive right to negotiate a definitive CLA for further development and commercialization of the Product Candidate. The Company determined that the license and research and development activities were not distinct from one another, as the license has limited value without the performance of research and development activities. The Company’s participation on the JRC was determined to be quantitatively and qualitatively immaterial and therefore is excluded from performance obligations. As such, the Company determined that the promises associated with the license and research and development services should be combined into a single performance obligation.

The Company next evaluated the milestone payments relating to the three phases of research as defined in the research plan and the option to negotiate and enter into the CLA, to determine whether they provide Roche with any material rights. The Company concluded that the option was not issued at a significant and incremental discount, and therefore do not provide material rights. As such, they were excluded as performance obligations at the outset of the arrangement. If Roche elects to exercise the options, the additional consideration will be added to the transaction price and allocated to the resulting performance obligations.

Based on these assessments, the Company identified one performance obligation at the outset of the Roche Collaboration and Option Agreement, which consists of: (1) the non-exclusive license and (2) the research and development activities.

At the outset of the arrangement, the transaction price included only the $1.0 million up-front consideration received and which was allocated to the single performance obligation. The milestone payments that may be received are excluded from the transaction price until each respective milestone has been achieved. The Company will reevaluate the transaction price at the end of each

reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, adjust its estimate of the transaction price.

In June 2021, the Company began work on the research and development services for the first phase of the research plan and the $1.0 million upfront payment is being recognized over the time of the first phase of the research plan. In September 2021, the Company completed the research and development services for the first phase of the research plan and achieved a milestone payment of $1.0 million, which was paid by Roche in November 2021. At this time, the milestone payment was allocated to a new performance obligation consisting of the underlying research and development services to be performed over the second phase of the research plan. Upon the Company’s completion of these activities and subject to Roche’s termination right, the additional milestone payments based on the achievement of specific events outlined in the Roche Collaboration and Option Agreement will become due.

Revenue associated with performance obligations under the Roche Collaboration and Option Agreement are recognized as the research and development services are provided using an input method, according to the full-time equivalents incurred. The transfer of control occurs over time and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation. The amounts received that have not yet been recognized as revenue are recorded in deferred revenue on the Company’s consolidated balance sheet.

The Company recognized $1.5 million for the year ended December 31, 2021 as collaboration revenue in the Company’s consolidated statements of operations and comprehensive loss. Deferred revenue from the collaboration amounted to $0.5 million as of December 31, 2021, all of which is included in current liabilities.

Ginkgo Collaboration

In 2017, the Company established a technology collaboration with Ginkgo. In June 2019, in connection with the issuance to Ginkgo of an aggregate of 6,340,771 shares of common stock and Pre-Funded Warrants to purchase an aggregate of 2,548,117 common stock (See Note 8), the Company expanded its collaboration and entered into an agreement with Ginkgo for the research and development of engineered microbial therapeutic products. Under the 2019 expanded agreement, the Company made a prepayment to Ginkgo of $30.0 million for its foundry services that will be provided to the Company over an initial term of five years. The prepayment of foundry services is recorded in prepaid expenses and other current assets and prepaid research and development, net of current portion on the December 31, 2020 consolidated balance sheet. At December 31, 2021, the Company had remaining balances of $1.9 million and $9.3 million of current and non-current pre-paid research and development costs related to this transaction, respectively. Upon the expiration of such initial term and, if applicable, an additional period, any portion of the prepayment that has not been used to purchase services from Ginkgo will be retained by Ginkgo.

AbbVie Collaboration Agreement

In May 2020, we announced the termination of our collaboration with AbbVie to develop Synthetic Biotic medicines for the treatment of types of IBD, including Crohn’s disease and ulcerative colitis. Upon termination, we regained all rights to develop these and new IBD Synthetic Biotic medicines for all effectors targeting IBD. This allows us to fully leverage our expertise in strain engineering, quantitative biology, regulatory, and manufacturing to expand our wholly owned GI-based program portfolio to include IBD. We further regained the rights to partner these IBD programs.

The Company recognized the remainder of the deferred revenue when the agreement was terminated in 2020. For the year ended December 31, 2020, $0.5 million was recognized for services performed and payments received under the AbbVie collaboration.