0001564590-21-010823 | 10-K | XBRL Viewer

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2020	Feb. 25, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	CBIO
Entity Registrant Name	Catalyst Biosciences, Inc.
Entity Central Index Key	0001124105
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		31,331,027
Entity Public Float			$ 128,362,589
ICFR Auditor Attestation Flag	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock
Security Exchange Name	NASDAQ
Entity File Number	000-51173
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	56-2020050
Entity Address, Address Line One	611 Gateway Blvd
Entity Address, Address Line Two	Suite 710
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	871-0761
Document Annual Report	true
Document Transition Report	false

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 30,360	$ 15,369
Short-term investments	48,994	61,496
Accounts receivable, net	3,313	15,000
Prepaid and other current assets	6,843	4,201
Total current assets	89,510	96,066
Long-term investments	2,543
Other assets, noncurrent	528	257
Right-of-use assets	1,832	1,927
Property and equipment, net	433	304
Total assets	94,846	98,554
Current liabilities:
Accounts payable	5,931	4,279
Accrued compensation	2,476	2,106
Deferred revenue	1,983	15,000
Other accrued liabilities	6,743	7,031
Operating lease liability	663	483
Total current liabilities	17,796	28,899
Operating lease liability, noncurrent	981	1,319
Total liabilities	18,777	30,218
Commitments and Contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized; zero shares issued and outstanding
Common stock, $0.001 par value, 100,000,000 shares authorized; 22,097,820 and 12,040,835 shares issued and outstanding at December 31, 2020 and 2019, respectively	22	12
Additional paid-in capital	390,803	326,810
Accumulated other comprehensive income	5	34
Accumulated deficit	(314,761)	(258,520)
Total stockholders’ equity	76,069	68,336
Total liabilities and stockholders’ equity	$ 94,846	$ 98,554

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	22,097,820	12,040,835
Common stock, shares outstanding	22,097,820	12,040,835

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
License and collaboration revenue	$ 20,948
Operating expenses:
Research and development	52,975	$ 43,859
General and administrative	16,180	13,418
Total operating expenses	78,318	57,277
Loss from operations	(57,370)	(57,277)
Interest and other income, net	1,129	2,099
Net loss	$ (56,241)	$ (55,178)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.93)	$ (4.60)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	19,179,299	12,004,489
License
License and collaboration revenue	$ 15,100
Collaboration
License and collaboration revenue	5,848
Cost of license
Operating expenses:
Cost of license and collaboration	3,102
Cost of collaboration
Operating expenses:
Cost of license and collaboration	$ 6,061

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (56,241)	$ (55,178)
Other comprehensive income (loss):
Unrealized (loss) gain on available-for-sale debt securities	(29)	38
Total comprehensive loss	$ (56,270)	$ (55,140)

- 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

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2018	$ 119,945	$ 12	$ 323,279	$ (4)	$ (203,342)
Balance (in shares) at Dec. 31, 2018		11,954,528
Stock-based compensation expense	3,204		3,204
Stock-based compensation expense		24,235
Issuance of common stock from ESPP purchases and stock option exercises	327		327
Issuance of common stock from ESPP purchases and stock option exercises, shares		62,072
Unrealized (loss) gain on available-for-sale debt securities	38			38
Net loss	(55,178)				(55,178)
Balance at Dec. 31, 2019	68,336	$ 12	326,810	34	(258,520)
Balance (in shares) at Dec. 31, 2019		12,040,835
Stock-based compensation expense	3,627		3,627
Stock-based compensation expense		51,056
Issuance of common stock from ESPP purchases and stock option exercises	435		435
Issuance of common stock from ESPP purchases and stock option exercises, shares		82,853
Issuance of common stock for public offering, net of issuance costs of $4,559	59,941	$ 10	59,931
Issuance of common stock for public offering, net of issuance costs, shares		9,923,076
Unrealized (loss) gain on available-for-sale debt securities	(29)			(29)
Net loss	(56,241)				(56,241)
Balance at Dec. 31, 2020	$ 76,069	$ 22	$ 390,803	$ 5	$ (314,761)
Balance (in shares) at Dec. 31, 2020		22,097,820

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance costs of issuance of common stock for public offering	$ 4,559

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Activities
Net loss	$ (56,241)	$ (55,178)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,627	3,204
Depreciation and amortization	138	146
Changes in operating assets and liabilities:
Accounts receivable	11,687	(15,000)
Prepaid and other assets	(3,043)	(490)
Accounts payable	1,652	3,031
Accrued compensation and other accrued liabilities	82	5,599
Operating lease liability and right-of-use asset	67	75
Deferred revenue	(13,017)	15,000
Net cash flows used in operating activities	(55,048)	(43,613)
Investing Activities
Proceeds from maturities of short-term investments	107,565	157,433
Purchase of short-term and long-term investments	(97,635)	(129,977)
Purchases of property and equipment	(267)	(64)
Net cash flows provided by investing activities	9,663	27,392
Financing Activities
Issuance of common stock for public offering, net of issuance costs	59,941
Issuance of common stock from ESPP purchase and stock option exercises	435	327
Net cash flows provided by financing activities	60,376	327
Net increase (decrease) in cash and cash equivalents	14,991	(15,894)
Cash and cash equivalents at beginning of the period	15,369	31,263
Cash and cash equivalents at end of the period	30,360	15,369
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Right-of-use asset and operating lease liability recorded upon the adoption of ASC 842		$ 2,052
Right-of-use assets obtained in exchange for operating lease liabilities	$ 476

Nature of Operations

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Operations

1.	Nature of Operations

Catalyst Biosciences, Inc. and its subsidiary (the “Company” or “Catalyst”) is a fully integrated research and clinical development biopharmaceutical company with expertise in protease engineering, discovery, translational research, clinical development, and manufacturing. The Company is focused on advancing its protease product candidates in the fields of hemostasis and complement regulation. The Company is located in South San Francisco, California and operates in one segment.

Liquidity

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Liquidity

The Company had a net loss of $56.2 million for the year ended December 31, 2020 and an accumulated deficit of $314.8 million as of December 31, 2020. The Company expects to continue to incur losses for the next several years. As of December 31, 2020, the Company had $81.9 million of cash, cash equivalents and investments. Its primary uses of cash are to fund operating expenses, including research and development expenditures and general and administrative expenditures. Based on the current status of its research and development plans, the Company believes that its existing cash, cash equivalents and investments as of December 31, 2020 will be sufficient to fund its cash requirements for at least the next 12 months from the date of the filing of this report. If, at any time, the Company’s prospects for financing its research and development programs decline, the Company may decide to reduce research and development expenses by delaying, discontinuing or reducing its funding of one or more of its research or development programs. Alternatively, the Company might raise funds through strategic collaborations, public or private financings or other arrangements. Such funding, if needed, may not be available on favorable terms, or at all. The Company will continue to evaluate the impact of the COVID-19 pandemic on our business, operations, and cash requirements. For recent financing, see Note 16.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements include the accounts of the Company and its subsidiary. Intercompany accounts and transactions, if applicable, have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”).

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance of doubtful accounts, operating lease right-of-use assets and liabilities, accrued expenses, income taxes and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Accounting Pronouncements Recently Adopted

In November 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 (“ASU 2018-18”). The amended guidance precludes presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. The new guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-18 as of January 1, 2020. The adoption of ASU 2018-18 did not have a material impact on the Company’s consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). The

guidance removes, modifies, and adds certain disclosure requirements for fair value measurements. Entities no longer have to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-13 as of January 1, 2020. The adoption of ASU 2018-13 did not have a material impact on the Company’s consolidated financial statements.

New Accounting Pronouncements – Issued But Not Yet Adopted

In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments, or ASU 2016-13. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about an entity's expected credit losses on financial instruments and other commitments to extend credit at each reporting date. To achieve this objective, the amendments in this update replace the incurred loss impairment methodology currently used today with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to develop credit loss estimates. ASU 2016-13 will be effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, using a modified retrospective approach. Early adoption is permitted. The Company plans to adopt ASU 2016-13 and related updates as of January 1, 2023. The Company will assess the impact of adoption of this standard on its consolidated financial statements.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in ASU 2019-12 are intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for the Company beginning January 1, 2021. The adoption of this standard will not have a material impact on the Company’s consolidated financial statements.

Cash and Cash Equivalents

The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.

Fair Value of Financial Instruments

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured:

Level 1 – Quoted prices in active markets for identical assets or liabilities.

Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for furniture and leasehold improvements.

Investments

The Company invests its excess cash in investment grade, short to intermediate-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each consolidated balance sheet date. Unrealized gains and losses on available-for-sale debt securities are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale debt securities are included in interest and other income, net. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income, net.

Revenue Recognition

License and Collaboration Arrangements

The Company may enter into collaboration arrangements that fall under the scope Collaborative Arrangements (Topic 808). The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be analogized to ASC 606 for distinct units of account that are reflective of a vendor-customer relationship.

Under ASC 606, in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, 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 based on estimated selling prices; and (v) recognition of revenue when the Company satisfies each performance obligation.

If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement 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.

At the inception of each arrangement that contain development milestones, the Company evaluates whether the development milestones included are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal 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 generally considered probable of being achieved until those approvals are received.

At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

For research and development services, the Company elected the practical expedient to recognize revenue as the research and development services are invoiced. As the Company has a right to consideration from the

collaboration agreement with Biogen, in an amount that corresponds directly with the value of the Company’s performance completed to date for the research services, the Company recognized revenue related to the research services as invoiced, in line with the practical expedient in ASC 606-10-55-18.

The transaction price is allocated to each performance obligation on a relative stand-alone selling price (“SSP”) basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the timing of recognition and the SSP for each performance obligation identified in the contract.

The SSP for licenses are calculated using the residual approach if the Company has not yet established a price for such license and the license has not previously been sold on a standalone basis. Otherwise, selling prices for licenses are determined using an income approach model and include key assumptions such as: development timeline, revenue forecast, commercialization expenses, discount rate and probabilities of technical and regulatory success. To estimate the SSP for research and development services, the Company uses a cost-plus margin approach.

Cost of License and Collaboration Revenue

Cost of license revenue includes sublicense fees paid or payable to Mosaic Biosciences, Inc. (“Mosaic”), incurred in the period, under the terms of the Mosaic collaboration agreement, and fees for patent development and protection paid or payable to other third-party vendors corresponding to the recognition of license revenue from the Company’s collaboration agreement with Biogen International GmbH (“Biogen”). See Notes 8 and 12. Cost of license revenue does not include any allocated overhead costs.

Cost of collaboration revenue includes fees for research and development services paid or payable to Mosaic and other third-party vendors and personnel cost, incurred in the period pertaining to the Biogen Agreement. See Notes 8 and 12. Cost of collaboration revenue does not include any allocated overhead costs.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreement with Biogen, certain specific expenditures are reimbursed by third parties. During the year ended December 31, 2020, $5.4 million of research and development expense was recorded as cost of collaboration revenue related to the collaboration agreement with Biogen signed in December 2019.

Accrued Research and Development Expenses

Accrued expenses include estimated costs of research and development activities conducted by external service providers, which include the conduct of preclinical studies and clinical trials and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in other accrued liabilities in the consolidated balance sheet and within research and development expense in the consolidated statement of operations. These costs are a significant component of the research and development expenses. The Company records accrued expenses for these costs based on the estimated amount of work completed and in accordance with agreements established with these external service providers.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, investments and accounts receivable. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company believes that it has established guidelines for investment of its excess cash that maintain safety and liquidity through its policies on high quality of investment and investment duration. The Company is exposed to credit risk in the event of default by the institutions holding the cash and cash equivalents to the extent beyond the amount insured by the federal depository insurance corporation. The Company’s accounts receivable as of December 31, 2020 of $3.3 million as well as its total license and collaboration revenue of $20.9 million for the year ended December 31, 2020 is from one party, see Note 12.

Accounts Receivable, net and Allowance for Doubtful Accounts

Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Customer payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangements. The Company continuously monitors collections and payments from its customers and maintains a provision for estimated credit losses. The Company determines its allowance for doubtful accounts by considering a number of factors, including the length of time balances are past due, the Company’s previous loss history, the customer’s current ability to pay its obligations to the Company and the condition of the general economy and the industry as a whole. The Company writes off accounts receivable when they are determined to be uncollectible. For the years ended December 31, 2020 and 2019, there were no allowance for doubtful accounts deemed necessary.

Income Taxes

Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures.

The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary.

Stock-Based Compensation

The Company measures the cost of employee, non-employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee, non-employee or director is required to provide service in exchange for the award on a straight-line basis.

The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. The Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, over their requisite service period, based on the vesting provisions of the individual grants.

Leases

At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received.

The Company has elected to combine lease and non-lease components as a single component. The lease expense is recognized over the expected term on a straight-line basis. Operating leases are recognized on the consolidated balance sheet as right-of-use assets, operating lease liabilities, current and operating lease liabilities, non-current.

Net Loss per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

4.	Fair Value Measurements

For a description of the fair value hierarchy and fair value methodology, see “Note 3 – Summary of Significant Accounting Policies”. As of December 31, 2020 and 2019, the Company’s highly liquid money market funds included within cash equivalents and U.S. government agency securities are valued using Level 1 inputs. The Company classifies its federal agency securities as Level 2. There were no transfers in or out of Level 1 and Level 2 during the periods presented. U.S. government agency securities are bonds issued by the U.S. government and are fully backed by the U.S. government. Given the frequency at which U.S. government agency securities trade and the accessibility of observable, quoted prices for such assets in active markets, they are recognized as Level 1 assets. Federal agency securities are bonds and notes issued by government-sponsored enterprises, including Fannie Mae, Freddie Mac and the Federal Home Loan Bank. Since Federal agency securities typically do not trade as U.S. government agency securities and no exchange exists to price such investments, they are recognized as Level 2 assets.

The following tables present the fair value hierarchy for assets measured at fair value on a recurring basis as of December 31, 2020 and 2019 (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	30,360	$	—	$	—	$	30,360
U.S. government agency securities⁽²⁾		37,837		—		—		37,837
Federal agency securities⁽²⁾		—		13,700		—		13,700
Total financial assets	$	68,197	$	13,700	$	—	$	81,897

(1)	Included in cash and cash equivalents on accompanying consolidated balance sheet.

(2)

Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities. $2.5 million of U.S. government agency securities are included in long-term investments on the accompanying consolidated balance sheets due to the maturity being more than 12 months.

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	15,369	$	—	$	—	$	15,369
U.S. government agency securities⁽²⁾		51,490		—		—		51,490
Federal agency securities⁽²⁾		—		10,006		—		10,006
Total financial assets	$	66,859	$	10,006	$	—	$	76,865

(1)	Included in cash and cash equivalents on accompanying consolidated balance sheet.

(2)	Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities.

The carrying amounts of cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturity of these instruments.

- 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

Financial Instruments

12 Months Ended

Dec. 31, 2020

Investments All Other Investments [Abstract]

Financial Instruments

5.	Financial Instruments

Cash equivalents and investments (debt securities) which are classified as available-for-sale securities, consisted of the following (in thousands):

December 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	30,360	$	—	$	—	$	30,360
U.S. government agency securities		37,835		2		—		37,837
Federal agency securities		13,697		3		—		13,700
Total financial assets	$	81,892	$	5	$	—	$	81,897
Classified as:
Cash and cash equivalents							$	30,360
Short-term investments								48,994
Long-term investments								2,543
							$	81,897

December 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	15,369	$	—	$	—	$	15,369
U.S. government agency securities		51,467		23		—		51,490
Federal agency securities		9,995		11		—		10,006
Total financial assets	$	76,831	$	34	$	—	$	76,865
Classified as:
Cash and cash equivalents							$	15,369
Short-term investments								61,496
							$	76,865

There have been no material realized gains or losses on available-for-sale debt securities for the periods presented. As of December 31, 2020, the remaining contractual maturities of $49.0 million of available-for-sale debt securities was less than one year and $2.5 million of available-for-sale debt securities were less than two years.

Other Accrued Liabilities

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Other Accrued Liabilities

6.	Other Accrued Liabilities

Other accrued liabilities consisted of the following (in thousands):

	Year Ended December 31,
	2020		2019
Professional and consulting services	$	3,979	$	2,026
Manufacturing		2,238		4,320
Clinical		291		435
Other		235		250
Total other accrued liabilities	$	6,743	$	7,031

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7.	Commitments and Contingencies

Manufacturing Agreements

On May 20, 2016, the Company signed a development and manufacturing services agreement with AGC Biologics, Inc. (“AGC”), formerly known as CMC ICOS Biologics, Inc., pursuant to which AGC will conduct manufacturing development of agreed upon product candidates. The Company has firm work orders with AGC to manufacture MarzAA and DalcA to support its clinical trials totaling $11.2 million and the payment obligations remaining at the year ended December 31, 2020 was $2.3 million.

On October 9, 2019, the Company and Catalent Indiana, LLC (“Catalent”) signed a clinical supply services agreement, effective October 4, 2019, pursuant to which Catalent will conduct drug product development of agreed upon product candidates. The Company had firm work orders with Catalent to manufacture DalcA to support its clinical trial totaling $0.5 million and all outstanding amounts were paid during the year ended December 31, 2020.

The current COVID-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting our employees, potential trial participants and business operations. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning COVID-19, the actions taken to contain it or treat its impact and the economic impact on local, regional, national, and international markets. The COVID-19 pandemic may disrupt the operations of the Company’s manufacturers or disrupt supply logistics, which could impact the timing of deliveries and potentially increase expenses under our agreements. All required MarzAA supplies for the MAA-304 and MAA-202 studies have been manufactured.

Related Parties

12 Months Ended

Dec. 31, 2020

Related Parties

8.	Related Parties

On October 24, 2017, the Company announced a strategic research collaboration with Mosaic to develop intravitreal anti-complement factor 3 (C3) products for the treatment of dry Age-related Macular Degeneration (AMD) and other retinal diseases. Dr. Usman, the Company’s Chief Executive Officer and a member of the Company’s board of directors, and Mr. Lawlor, a member of the Company’s board of directors, were also members of the board of directors of Mosaic. On December 21, 2018, the Company amended its collaboration agreement with Mosaic to, among other things, include certain additional products. Pursuant to the Mosaic collaboration agreement, as amended, the Company and Mosaic co-funded certain research.

On December 18, 2019, the Company entered into the second amendment to the Mosaic collaboration agreement following completion of the co-funded research. Pursuant to the second amendment, any future services provided by Mosaic will be performed on a fee-for-service basis. In connection with the Biogen Agreement, the Company received a $15.0 million upfront license fee on January 10, 2020, see Note 12. The Company paid Mosaic a $3.0 million sublicense fee and recorded such payment as cost of license revenue for the year ended December 31, 2020.

On May 8, 2020, the Company entered into a subsequent amendment to the Mosaic collaboration agreement. As part of this amendment, the Company paid a one-time $0.8 million cash payment to Mosaic, and Mosaic is eligible to receive up to $4.0 million in potential future milestone payments related to regulatory and clinical development events for CB 2782-PEG and an additional anti-complement product candidate in lieu of the Company’s obligations to pay Mosaic a double-digit percentage of funds the Company receives from Biogen or any other amounts the Company receives related to sublicense fees, research and development payments, or any other research, regulatory, clinical or commercial milestones and royalties on any other development candidates. The Company now owns one hundred percent of all future payment streams related to these product candidates.

The one-time $0.8 million cash payment was recorded to research and development expenses for the year ended December 31, 2020.

As of June 30, 2020, Mosaic was no longer a related party. Total expense related to the collaboration with Mosaic were $1.6 million for the year ended December 31, 2020, of which expense recognized while Mosaic was a related party were $1.3 million, and $1.1 million for the year ended December 31, 2019. The amount incurred in 2020 is fully reimbursable under the Biogen Agreement, see Note 12.

Leases

12 Months Ended

Dec. 31, 2020

Lessee Disclosure [Abstract]

Leases

The Company leases office space for its corporate headquarters, located in South San Francisco, CA. The lease term is through April 30, 2023 and there are no stated renewal options. Operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term. In calculating the present value of the lease payments, the Company has elected to utilize its incremental borrowing rate based on the original lease term and not the remaining lease term. The lease includes non-lease components (e.g., common area maintenance) that are paid separately from rent based on actual costs incurred and therefore were not included in the right-of-use asset and lease liability but are reflected as an expense in the period incurred.

On July 17, 2020, the Company entered into an amendment to the existing lease agreement to lease additional office space for an aggregated undiscounted future monthly payment of $0.5 million. This amendment is treated as a separate lease with a lease term of 2.6 years and commenced during the fourth quarter of 2020.

For the years ended December 31, 2020 and 2019, the Company’s operating lease expense was $0.7 million and $0.6 million, respectively. The present value assumptions used in calculating the present value of the lease payments were as follows:

	December 31,			December 31,
	2020			2019
Weighted-average remaining lease term	2.33 years			3.33 years
Weighted-average discount rate		5.7	%		6.0	%

The maturity of the Company’s operating lease liabilities as of December 31, 2020 were as follows (in thousands):

Undiscounted lease payments	Operating Leases
2021	$	739
2022		762
2023		259
Total undiscounted lease payments		1,760
Less: imputed interest		(116	)
Total operating lease liability	$	1,644

Under the terms of the lease agreements, the Company is also responsible for certain variable lease payments that are not included in the measurement of the lease liability. The Company did not incur significant variable lease costs for the years ended December 31, 2020 and 2019.

Supplemental cash flow information for the years ended December 31, 2020 and 2019 related to operating leases was as follows (in thousands):


	Year Ended December 31,
	2020		2019
Cash paid for leases that were included in operating cash outflows	$	602	$	562

Stock Based Compensation

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Compensation

10.	Stock Based Compensation

2018 Omnibus Incentive Plan

In June 2018, stockholders of the Company approved the Company’s 2018 Omnibus Incentive Plan (the “2018 Plan”). The 2018 Plan had previously been approved by the Company’s Board of Directors (the “Board”) and the Compensation Committee of the Board, subject to stockholder approval. The 2018 Plan became effective on June 13, 2018. On June 11, 2020, the stockholders of the Company approved an amendment previously approved by the Board to increase the number of shares of common stock reserved for issuance under the 2018 Plan by 1,300,000 to a total of 2,800,000 shares. The amendment became effective immediately upon stockholder approval.

The following table summarizes stock option activity under the Company’s equity incentive plans and related information:

	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (thousands)
Outstanding — December 31, 2018		1,361,977		$	12.04		8.71	$	2,294
Options granted		450,900			7.85
Options exercised		(41,219	)		4.57				159
Options forfeited		(182,722	)		8.36
Options expired		(11,395	)		96.49
Outstanding — December 31, 2019		1,577,541			10.85		8.15		1,350
Options granted		1,091,250			6.26
Options exercised		(44,605	)		5.04				116
Options forfeited		(250,641	)		10.32
Options expired		(17,930	)		51.12
Outstanding — December 31, 2020		2,355,615			8.59		7.96		1,337
Exercisable — December 31, 2020		1,113,791		$	10.45		7.14	$	823
Shares available to be granted — December 31, 2020		1,255,302

Valuation Assumptions

The Company estimated the fair value of stock options granted using the Black-Scholes option-pricing formula and a single option award approach. Due to its limited history as a public company and limited number of sales of its common stock, the Company estimated its volatility considering a number of factors including the use of the volatility of comparable public companies. The expected term of options granted under the Plan, all of which qualify as “plain vanilla” per SEC Staff Accounting Bulletin 107, is determined based on the simplified method due to the Company’s limited operating history. The risk-free rate is based on the yield of a U.S. Treasury security with a term consistent with the option. This fair value is being amortized ratably over the requisite service periods of the awards, which is generally the vesting period.

The fair value of employee stock options was estimated using the following weighted-average assumptions for the years ended December 31, 2020 and 2019:

	Year Ended December 31,
	2020			2019
Employee Stock Options:
Expected term (in years)		5.81			5.98
Risk-free interest rate		0.91	%		2.35	%
Dividend yield		—			—
Volatility		113.36	%		90.81	%
Weighted-average fair value of stock options granted	$	5.20		$	5.85

Total stock-based compensation recognized was as follows (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	1,487	$	1,052
General and administrative⁽¹⁾		2,140		2,152
Total stock-based compensation	$	3,627	$	3,204

(1)	Included in general and administrative stock-based compensation for the years ended December 31, 2020 and 2019 is $0.3 million and $0.2 million in expense related to 51,056 shares and 24,235 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

As of December 31, 2020, 1,255,302 shares of common stock were available for future grant and 2,355,615 options to purchase shares of common stock were outstanding. As of December 31, 2020, the Company had unrecognized employee stock-based compensation expense of $6.5 million, related to unvested stock option awards, which is expected to be recognized over an estimated weighted-average period of 2.63 years.

Employee Stock Purchase Plan

In June 2018, the Company’s stockholders approved the 2018 Employee Stock Purchase Plan (the “ESPP”). The ESPP had previously been approved by the Board and the Compensation Committee of the Board, subject to stockholder approval which became effective as of June 13, 2018. Under the ESPP, employees meeting certain specific employment qualifications are eligible to participate and can purchase shares of common stock semi-annually on February 9^th and August 9^th of each year, through payroll deductions. The purchase price is 85% of the lower of the fair market value of the stock at the commencement or end of the offering period. The ESPP permits eligible employees to purchase shares of common stock through payroll deductions for up to 15% of qualified compensation.

The Company’s ESPP is subject to an Evergreen provision which shares may be added to the pool as needed. As of December 31, 2020, a total of 359,545 shares of common stock may be granted in accordance with the terms of the ESPP as of December 31, 2020.

For the year ended December 31, 2020, a total of 38,248 shares of common stock for $0.2 million have been issued to employees participating in the two ESPP purchases of 2020 and 300,444 shares are available for issuance under the ESPP as of December 31, 2020.

Stock-based compensation expense for the ESPP was $0.1 million and $0.1 million for the years ended December 31, 2020 and 2019, respectively, and is included in total stock-based compensation recognized.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

11.	Income Taxes

The Company has incurred cumulative net operating losses since inception and, consequently, has not recorded any income tax expense for the years ended December 31, 2020 and 2019 due to its net operating loss position.

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2020 and 2019 are as follows:

	Year Ended December 31,
	2020			2019
Tax at statutory federal rate		-21.00	%		-21.00	%
State Tax (benefit)—net of federal benefit		0.00	%		-0.06	%
Permanent differences		0.58	%		0.43	%
Tax credits		-12.26	%		-11.20	%
Derecognition due to Sec. 382 and 383 limitations		44.55	%		0.00	%
Change in valuation allowance		-12.25	%		31.20	%
Other		0.38	%		0.63	%
Effective tax rate		0.00	%		0.00	%

Significant components of the Company’s deferred tax assets as of December 31, 2020 and 2019 consist of the following (in thousands):

	Year Ended December 31,
	2020			2019
Deferred tax assets:
Accruals and reserves	$	1,095		$	936
Net operating loss carry forwards		29,505			34,392
Tax credit carry forwards		7,789			9,945
Fixed and intangible assets		7			10
Valuation allowance		(38,396	)		(45,283	)
Net deferred tax assets:	$	—		$	—

Based on the available objective evidence at December 31, 2020, the Company does not believe it is more likely than not that the net deferred tax assets will be realizable. Accordingly, the Company has provided a full valuation allowance against its net deferred tax assets at December 31, 2020 and 2019. The net valuation allowance decreased by approximately $6.9 million and increased by approximately $17.2 million during the years ended December 31, 2020 and 2019, respectively.

As of December 31, 2020, after consideration of certain limitations (see below), the Company had approximately $140.4 million federal and $8.0 million state net operating loss carryforwards (“NOL”) available to reduce future taxable income which, if unused, will begin to expire in 2037 for federal and 2032 for state tax purposes. The federal net operating loss carryforward includes $132.9 million that have an indefinite life.

As of December 31, 2020, the Company also had tax credit carry forwards available to offset future tax liabilities of approximately $5.0 million for federal and $6.8 million for state. If unused, the federal credit will begin to expire in 2040 and the state tax credit does not expire.

If the Company experiences a greater than 50 percent aggregate change in ownership over a three-year period (a Section 382 ownership change), utilization of its pre-change NOL carryforwards are subject to annual limitation under Section 382 of the Internal Revenue Code (California has similar provisions). The annual limitation is determined by multiplying the value of the Company's stock at the time of such ownership change by the applicable long-term tax-exempt rate. Such limitations may result in expiration of a portion of the NOL carryforwards before utilization. The Company determined that ownership changes occurred December 31, 2007, August 20, 2015, April 13, 2017, February 15, 2018, and February 18, 2020. Approximately $156.3 million and $70.8 million of the NOLs will expire unutilized for federal and California purposes, respectively. The Company has derecognized NOL related deferred tax assets in the tax affected amounts of $32.8 million and $0 for federal and California purposes, respectively.

All of the federal R&D credits could expire unutilized, whereas none of the California R&D credits are subject to expiration. Approximately $15.2 million of gross federal R&D credit-related deferred tax assets were derecognized due to the Section 383 limitation. The ability of the Company to use its remaining NOL carryforwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership.

On March 27, 2020, the “Coronavirus Aid, Relief and Economic Security (CARES) Act” (the “Act”) was signed into law. The Act includes provisions relating to refundable payroll tax credits, deferment of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, and modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The Company analyzed the provisions of the Act and determined there was no significant impact to its 2020 tax provision.

On June 29, 2020, the California Governor signed Assembly Bill 85 (“A.B. 85”), which now becomes California law. A.B. 85, which includes several tax measures, provides for a three-year suspension of the use of net operating losses for medium and large businesses and a three-year cap on the use of business incentive tax credits to offset no more than $5 million of tax per year. Generally, A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021, and 2022 for taxpayers with taxable income of $1 million or

more. Since the Company is not expected to generate California source taxable income of more than $1 million, no material impact is anticipated at this time.

On December 27, 2020, the “Consolidated Appropriations Act, 2021” (the “CAA”) was signed into law. The CAA includes provisions meant to clarify and modify certain items put forth in CARES Act, while providing aid to businesses affected by the pandemic. The CAA allows deductions for expenses paid for by Paycheck Protection Program (“PPP”) and Economic Injury Disaster Loan (“EIDL”) Program, clarifies forgiveness of EIDL advances, and other business provisions. The Company analyzed the provisions of the CAA and determined there was no significant impact to its 2020 tax provision.

Accounting for Uncertainty in Income Taxes

The Company only recognizes tax benefits if it is more likely than not that they will be sustained upon audit by the relevant tax authority based upon their technical merits. An uncertain tax position will not be recognized if it has less than a 50% likelihood of being sustained.

The Company had approximately $3.0 million and $1.9 million of unrecognized tax benefits as of December 31, 2020 and 2019, respectively. As the Company has a full valuation allowance on its deferred tax assets, the unrecognized tax benefits have reduced the deferred tax assets and the valuation allowance in the same amount. The Company does not expect the amount of unrecognized tax benefits to materially change in the next twelve months.

A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):

Beginning Balance at January 1, 2019	$	1,573
Increase/(Decrease) of unrecognized tax benefits taken in prior years		45
Increase/(Decrease) of unrecognized tax benefits related to current year		253
Ending Balance at December 31, 2019	$	1,871
Increase/(Decrease) of unrecognized tax benefits taken in prior years		(295	)
Increase/(Decrease) of unrecognized tax benefits related to current year		1,379
Ending Balance at December 31, 2020	$	2,955

Interest and penalties related to unrecognized tax benefits would be included as income tax expense in the Company’s consolidated statements of operations. As of December 31, 2020 and 2019, the Company had not recognized any tax-related penalties or interest in its consolidated financial statements.

The Company files income tax returns in the United States federal, California, Kansas, Missouri and New Jersey state jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. As of December 31, 2020 and 2019, the Company had no uncertain tax positions which affected its financial position as its results of operations or its cash flow, and will continue to evaluate for uncertain tax positions in the future. The Company is subject to United States federal and state income tax examinations by authorities for all tax years due to accumulated net operating losses that are being carried forward for tax purposes.

- 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 + Details

Collaborations

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaborations

12.	Collaborations

Pfizer

Pursuant to the termination agreement entered into on December 8, 2016, in connection with the termination of a prior license and development agreement, Pfizer granted the Company an exclusive license to Pfizer’s proprietary rights for manufacturing materials and processes that apply to Factor VIIa variants, CB 813a and marzeptacog alfa (activated) - MarzAA. Pfizer also transferred to the Company the IND application and documentation related to the development, manufacturing and testing of the Factor VIIa products as well as

the orphan drug designation. The Company agreed to make contingent cash payments to Pfizer in an aggregate amount up to $17.5 million, payable upon the achievement of certain clinical, regulatory and commercial milestones. Following commercialization of any covered product, Pfizer will also receive a single-digit royalty on net product sales on a country-by-country basis for a predefined royalty term. In February 2018, the Company paid Pfizer a $1.0 million milestone payment based on the dosing of the first patient in its Phase 2 study; the amount was recorded as a research and development expense. No payments were made to Pfizer in the year ended December 31, 2020.

ISU Abxis

In December 2018, the Company entered into an amended and restated license agreement with ISU Abxis (the “A&R ISU Abxis Agreement”), which amended and restated its previous license and collaboration agreement with ISU Abxis previously entered into in September 2013, as subsequently amended in October 2014 and December 2016 (the “Original ISU Abxis Agreement”). Under the A&R ISU Abxis Agreement, ISU Abxis will receive commercialization rights in South Korea to the Company’s engineered Factor IX dalcinonacog alfa - DalcA and the Company will receive clinical development and commercialization rights in the rest of world (excluding South Korea) and manufacturing development and manufacturing rights worldwide (including South Korea). The A&R ISU Abxis Agreement eliminates the profit-sharing arrangement in the Original ISU Abxis Agreement and provides for a low single-digit royalty payment to ISU Abxis, on a country-by-country basis, for net product sales of DalcA by the Company or its affiliates in each country other than South Korea. Pursuant to the A&R ISU Abxis Agreement, the Company will also pay up to an aggregate of $19.5 million in milestone payments to ISU Abxis, including $2.5 million in regulatory and development milestone payments and up to $17.0 million in commercial milestone payments, if the applicable milestones are met. As of December 31, 2020, no milestones have been met.

Biogen

On December 18, 2019, the Company and Biogen International GmbH (“Biogen”) entered into a License and Collaboration Agreement (the “Biogen Agreement”), under which the Company granted Biogen a worldwide, royalty-bearing, exclusive, with the right to sublicense, license (“Exclusive License”) to develop and commercialize CB 2782-PEG and other anti-C3 proteases for potential treatment of dry AMD and other disorders. Pursuant to the Biogen Agreement, the Company will perform certain pre-clinical and manufacturing activities (“Research Services”), and Biogen will be solely responsible for funding the pre-clinical and manufacturing activities and performing IND-enabling activities, worldwide clinical development, and commercialization. The Company will provide the Research Services over a term of thirty months with Biogen having the option to extend the term for two additional twelve-month periods.

Under the terms of the Biogen Agreement, the Company received an up-front payment for the transfer of the Exclusive License (inclusive of certain know-how) of $15.0 million in January 2020. The Company is eligible to receive development milestones and sales milestones of up to $340.0 million. In addition, the Company is eligible to receive royalties in the range of single-digit to low double-digit percentage rates of annual net sales on a product-by-product and country-by-country basis. The Company will also receive reimbursements for costs associated with the performance of the Research Services.

The Company determined that the performance obligations under the Biogen Agreement were the Exclusive License and the Research Services. For the Exclusive License, the Company used the residual approach in determining the standalone selling price, or SSP, which includes the upfront payments, milestones and royalties. For the Research Services, the Company used the historical pricing approach for determining the SSP, which includes the reimbursement of personnel and out-of-pocket costs.

The Biogen Agreement will continue on a product-by-product and country-by-country basis until the tenth anniversary of the first commercial sale of the first product in a country, unless terminated earlier by either party as specified under the agreement.

For the year ended December 31, 2020, the Company recognized the $15.0 million in license revenue upon the transfer of the Exclusive License and the related know-how, and $0.1 million in license revenue for reimbursable out-of-pocket costs incurred.

For the year ended December 31, 2020, the Company recorded $5.8 million in collaboration revenue for reimbursable out-of-pocket and personnel costs incurred related to research services.

Interest and Other Income, Net

12 Months Ended

Dec. 31, 2020

Other Income And Expenses [Abstract]

Interest and Other Income, Net

13.	Interest and Other Income, Net

The following table shows the detail of interest and other income, net for the years ended December 31, 2020 and 2019 (in thousands):

	Year Ended December 31,
	2020			2019
Interest income	$	561		$	2,145
Miscellaneous income (expense)		659			(39	)
Other		(91	)		(7	)
Total interest and other income, net	$	1,129		$	2,099

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Stockholders' Equity

14.	Stockholders’ Equity

In February 2020, the Company completed an underwritten public offering of 5,307,692 shares of its common stock (including 692,307 shares sold pursuant to the exercise of the underwriters’ overallotment option) at a price of $6.50 per share. The net proceeds to the Company, after deducting $2.5 million in underwriting discounts and commissions and offering expenses payable by the Company, were approximately $32.0 million.

In June 2020, the Company completed an underwritten public offering of 4,615,384 shares of its common stock at a price of $6.50 per share. The net proceeds to the Company, after deducting $2.0 million in underwriting discounts and commissions and offering expenses payable by the Company, were approximately $28.0 million.

The Company had issued and outstanding common stock warrants as follows:

	Number of Shares			Weighted Average
	Underlying Warrants			Exercise Price
Outstanding — December 31, 2018		10,194		$	155.73
Issued		—
Exercised		—
Forfeited		(2,337	)		499.50
Outstanding — December 31, 2019		7,857			53.61
Issued		—
Exercised		—
Forfeited		(7,772	)		49.91
Outstanding — December 31, 2020		85		$	392.70

Net Loss per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss per Share Attributable to Common Stockholders

15.	Net Loss per Share Attributable to Common Stockholders

The following table sets forth the computation of the basic and diluted net loss per common share during the years ended December 31, 2020 and 2019 (in thousands, except share and per share data):

	Year Ended December 31,
	2020			2019
Net loss	$	(56,241	)	$	(55,178	)
Weighted-average number of shares used in computing net loss per share, basic and diluted		19,179,299			12,004,489
Net loss per share, basic and diluted	$	(2.93	)	$	(4.60	)

Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	Year Ended December 31,
	2020		2019
Options to purchase common stock		2,355,615		1,577,541
Common stock warrants		85		7,857
Total		2,355,700		1,585,398

Subsequent Event

12 Months Ended

Dec. 31, 2020

Subsequent Events [Abstract]

Subsequent Event

16.	Subsequent Event

In the first quarter of 2021, we sold an aggregate of 9,185,000 registered shares of common stock (including 485,000 shares sold pursuant to the exercise of the underwriters’ overallotment option) at a price of $5.75 per share. The net proceeds, after deducting $3.5 million underwriting discounts and offering expenses, were approximately $49.3 million.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its subsidiary. Intercompany accounts and transactions, if applicable, have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance of doubtful accounts, operating lease right-of-use assets and liabilities, accrued expenses, income taxes and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted In November 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 (“ASU 2018-18”). The amended guidance precludes presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. The new guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-18 as of January 1, 2020. The adoption of ASU 2018-18 did not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). The guidance removes, modifies, and adds certain disclosure requirements for fair value measurements. Entities no longer have to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-13 as of January 1, 2020. The adoption of ASU 2018-13 did not have a material impact on the Company’s consolidated financial statements. New Accounting Pronouncements – Issued But Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments, or ASU 2016-13. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about an entity's expected credit losses on financial instruments and other commitments to extend credit at each reporting date. To achieve this objective, the amendments in this update replace the incurred loss impairment methodology currently used today with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to develop credit loss estimates. ASU 2016-13 will be effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, using a modified retrospective approach. Early adoption is permitted. The Company plans to adopt ASU 2016-13 and related updates as of January 1, 2023. The Company will assess the impact of adoption of this standard on its consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in ASU 2019-12 are intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for the Company beginning January 1, 2021. The adoption of this standard will not have a material impact on the Company’s consolidated financial statements.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for furniture and leasehold improvements.
Investments	Investments The Company invests its excess cash in investment grade, short to intermediate-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each consolidated balance sheet date. Unrealized gains and losses on available-for-sale debt securities are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale debt securities are included in interest and other income, net. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income, net.
Revenue Recognition	Revenue Recognition License and Collaboration Arrangements The Company may enter into collaboration arrangements that fall under the scope Collaborative Arrangements (Topic 808). The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be analogized to ASC 606 for distinct units of account that are reflective of a vendor-customer relationship. Under ASC 606, in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, 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 based on estimated selling prices; and (v) recognition of revenue when the Company satisfies each performance obligation. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement 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. At the inception of each arrangement that contain development milestones, the Company evaluates whether the development milestones included are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal 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 generally considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For research and development services, the Company elected the practical expedient to recognize revenue as the research and development services are invoiced. As the Company has a right to consideration from the collaboration agreement with Biogen, in an amount that corresponds directly with the value of the Company’s performance completed to date for the research services, the Company recognized revenue related to the research services as invoiced, in line with the practical expedient in ASC 606-10-55-18. The transaction price is allocated to each performance obligation on a relative stand-alone selling price (“SSP”) basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the timing of recognition and the SSP for each performance obligation identified in the contract. The SSP for licenses are calculated using the residual approach if the Company has not yet established a price for such license and the license has not previously been sold on a standalone basis. Otherwise, selling prices for licenses are determined using an income approach model and include key assumptions such as: development timeline, revenue forecast, commercialization expenses, discount rate and probabilities of technical and regulatory success. To estimate the SSP for research and development services, the Company uses a cost-plus margin approach.
Cost of License and Collaboration Revenue	Cost of License and Collaboration Revenue Cost of license revenue includes sublicense fees paid or payable to Mosaic Biosciences, Inc. (“Mosaic”), incurred in the period, under the terms of the Mosaic collaboration agreement, and fees for patent development and protection paid or payable to other third-party vendors corresponding to the recognition of license revenue from the Company’s collaboration agreement with Biogen International GmbH (“Biogen”). See Notes 8 and 12. Cost of license revenue does not include any allocated overhead costs. Cost of collaboration revenue includes fees for research and development services paid or payable to Mosaic and other third-party vendors and personnel cost, incurred in the period pertaining to the Biogen Agreement. See Notes 8 and 12. Cost of collaboration revenue does not include any allocated overhead costs.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreement with Biogen, certain specific expenditures are reimbursed by third parties. During the year ended December 31, 2020, $5.4 million of research and development expense was recorded as cost of collaboration revenue related to the collaboration agreement with Biogen signed in December 2019.
Accrued Research and Development Expenses	Accrued Research and Development Expenses Accrued expenses include estimated costs of research and development activities conducted by external service providers, which include the conduct of preclinical studies and clinical trials and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in other accrued liabilities in the consolidated balance sheet and within research and development expense in the consolidated statement of operations. These costs are a significant component of the research and development expenses. The Company records accrued expenses for these costs based on the estimated amount of work completed and in accordance with agreements established with these external service providers.
Concentration Risk Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, investments and accounts receivable. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company believes that it has established guidelines for investment of its excess cash that maintain safety and liquidity through its policies on high quality of investment and investment duration. The Company is exposed to credit risk in the event of default by the institutions holding the cash and cash equivalents to the extent beyond the amount insured by the federal depository insurance corporation. The Company’s accounts receivable as of December 31, 2020 of $3.3 million as well as its total license and collaboration revenue of $20.9 million for the year ended December 31, 2020 is from one party, see Note 12.
Accounts Receivable, net and Allowance for Doubtful Accounts	Accounts Receivable, net and Allowance for Doubtful Accounts Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Customer payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangements. The Company continuously monitors collections and payments from its customers and maintains a provision for estimated credit losses. The Company determines its allowance for doubtful accounts by considering a number of factors, including the length of time balances are past due, the Company’s previous loss history, the customer’s current ability to pay its obligations to the Company and the condition of the general economy and the industry as a whole. The Company writes off accounts receivable when they are determined to be uncollectible. For the years ended December 31, 2020 and 2019, there were no allowance for doubtful accounts deemed necessary.
Income Taxes	Income Taxes Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures. The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary.
Stock-Based Compensation	Stock-Based Compensation The Company measures the cost of employee, non-employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee, non-employee or director is required to provide service in exchange for the award on a straight-line basis. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. The Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, over their requisite service period, based on the vesting provisions of the individual grants.
Leases	Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The Company has elected to combine lease and non-lease components as a single component. The lease expense is recognized over the expected term on a straight-line basis. Operating leases are recognized on the consolidated balance sheet as right-of-use assets, operating lease liabilities, current and operating lease liabilities, non-current.
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables present the fair value hierarchy for assets measured at fair value on a recurring basis as of December 31, 2020 and 2019 (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	30,360	$	—	$	—	$	30,360
U.S. government agency securities⁽²⁾		37,837		—		—		37,837
Federal agency securities⁽²⁾		—		13,700		—		13,700
Total financial assets	$	68,197	$	13,700	$	—	$	81,897

(1)	Included in cash and cash equivalents on accompanying consolidated balance sheet.

(2)

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	15,369	$	—	$	—	$	15,369
U.S. government agency securities⁽²⁾		51,490		—		—		51,490
Federal agency securities⁽²⁾		—		10,006		—		10,006
Total financial assets	$	66,859	$	10,006	$	—	$	76,865

(1)	Included in cash and cash equivalents on accompanying consolidated balance sheet.

(2)	Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities.

The carrying amounts of cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturity of these instruments.

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Investments All Other Investments [Abstract]

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities

Cash equivalents and investments (debt securities) which are classified as available-for-sale securities, consisted of the following (in thousands):

December 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	30,360	$	—	$	—	$	30,360
U.S. government agency securities		37,835		2		—		37,837
Federal agency securities		13,697		3		—		13,700
Total financial assets	$	81,892	$	5	$	—	$	81,897
Classified as:
Cash and cash equivalents							$	30,360
Short-term investments								48,994
Long-term investments								2,543
							$	81,897

December 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	15,369	$	—	$	—	$	15,369
U.S. government agency securities		51,467		23		—		51,490
Federal agency securities		9,995		11		—		10,006
Total financial assets	$	76,831	$	34	$	—	$	76,865
Classified as:
Cash and cash equivalents							$	15,369
Short-term investments								61,496
							$	76,865

Other Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Schedule of Other Accrued Liabilities

Other accrued liabilities consisted of the following (in thousands):

	Year Ended December 31,
	2020		2019
Professional and consulting services	$	3,979	$	2,026
Manufacturing		2,238		4,320
Clinical		291		435
Other		235		250
Total other accrued liabilities	$	6,743	$	7,031

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Lessee Disclosure [Abstract]

Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments

The present value assumptions used in calculating the present value of the lease payments were as follows:

	December 31,			December 31,
	2020			2019
Weighted-average remaining lease term	2.33 years			3.33 years
Weighted-average discount rate		5.7	%		6.0	%

Schedule of Maturity of Operating Lease Liabilities

The maturity of the Company’s operating lease liabilities as of December 31, 2020 were as follows (in thousands):

Undiscounted lease payments	Operating Leases
2021	$	739
2022		762
2023		259
Total undiscounted lease payments		1,760
Less: imputed interest		(116	)
Total operating lease liability	$	1,644

Schedule of Supplemental Cash Flow Information

Supplemental cash flow information for the years ended December 31, 2020 and 2019 related to operating leases was as follows (in thousands):


	Year Ended December 31,
	2020		2019
Cash paid for leases that were included in operating cash outflows	$	602	$	562

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Option Activity Under Company's Equity Incentive Plans

The following table summarizes stock option activity under the Company’s equity incentive plans and related information:

	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (thousands)
Outstanding — December 31, 2018		1,361,977		$	12.04		8.71	$	2,294
Options granted		450,900			7.85
Options exercised		(41,219	)		4.57				159
Options forfeited		(182,722	)		8.36
Options expired		(11,395	)		96.49
Outstanding — December 31, 2019		1,577,541			10.85		8.15		1,350
Options granted		1,091,250			6.26
Options exercised		(44,605	)		5.04				116
Options forfeited		(250,641	)		10.32
Options expired		(17,930	)		51.12
Outstanding — December 31, 2020		2,355,615			8.59		7.96		1,337
Exercisable — December 31, 2020		1,113,791		$	10.45		7.14	$	823
Shares available to be granted — December 31, 2020		1,255,302

Summary of Weighted Average Valuation Assumptions Used to Estimate Fair Value of Employee Stock Options

The fair value of employee stock options was estimated using the following weighted-average assumptions for the years ended December 31, 2020 and 2019:

	Year Ended December 31,
	2020			2019
Employee Stock Options:
Expected term (in years)		5.81			5.98
Risk-free interest rate		0.91	%		2.35	%
Dividend yield		—			—
Volatility		113.36	%		90.81	%
Weighted-average fair value of stock options granted	$	5.20		$	5.85

Summary of Stock-Based Compensation Recognized

Total stock-based compensation recognized was as follows (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	1,487	$	1,052
General and administrative⁽¹⁾		2,140		2,152
Total stock-based compensation	$	3,627	$	3,204

(1)	Included in general and administrative stock-based compensation for the years ended December 31, 2020 and 2019 is $0.3 million and $0.2 million in expense related to 51,056 shares and 24,235 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

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

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2020 and 2019 are as follows:

	Year Ended December 31,
	2020			2019
Tax at statutory federal rate		-21.00	%		-21.00	%
State Tax (benefit)—net of federal benefit		0.00	%		-0.06	%
Permanent differences		0.58	%		0.43	%
Tax credits		-12.26	%		-11.20	%
Derecognition due to Sec. 382 and 383 limitations		44.55	%		0.00	%
Change in valuation allowance		-12.25	%		31.20	%
Other		0.38	%		0.63	%
Effective tax rate		0.00	%		0.00	%

Components of the Company's Deferred Tax Assets (Liabilities)

Significant components of the Company’s deferred tax assets as of December 31, 2020 and 2019 consist of the following (in thousands):

	Year Ended December 31,
	2020			2019
Deferred tax assets:
Accruals and reserves	$	1,095		$	936
Net operating loss carry forwards		29,505			34,392
Tax credit carry forwards		7,789			9,945
Fixed and intangible assets		7			10
Valuation allowance		(38,396	)		(45,283	)
Net deferred tax assets:	$	—		$	—

Unrecognized Tax Benefits

A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):

Beginning Balance at January 1, 2019	$	1,573
Increase/(Decrease) of unrecognized tax benefits taken in prior years		45
Increase/(Decrease) of unrecognized tax benefits related to current year		253
Ending Balance at December 31, 2019	$	1,871
Increase/(Decrease) of unrecognized tax benefits taken in prior years		(295	)
Increase/(Decrease) of unrecognized tax benefits related to current year		1,379
Ending Balance at December 31, 2020	$	2,955

Interest and Other Income, Net (Tables)

12 Months Ended

Dec. 31, 2020

Other Income And Expenses [Abstract]

Detail of Interest and Other Income, Net

The following table shows the detail of interest and other income, net for the years ended December 31, 2020 and 2019 (in thousands):

	Year Ended December 31,
	2020			2019
Interest income	$	561		$	2,145
Miscellaneous income (expense)		659			(39	)
Other		(91	)		(7	)
Total interest and other income, net	$	1,129		$	2,099

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Warrant Activity

The Company had issued and outstanding common stock warrants as follows:

	Number of Shares			Weighted Average
	Underlying Warrants			Exercise Price
Outstanding — December 31, 2018		10,194		$	155.73
Issued		—
Exercised		—
Forfeited		(2,337	)		499.50
Outstanding — December 31, 2019		7,857			53.61
Issued		—
Exercised		—
Forfeited		(7,772	)		49.91
Outstanding — December 31, 2020		85		$	392.70

Net Loss per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Basic and Diluted Net Loss Per Common Share

The following table sets forth the computation of the basic and diluted net loss per common share during the years ended December 31, 2020 and 2019 (in thousands, except share and per share data):

	Year Ended December 31,
	2020			2019
Net loss	$	(56,241	)	$	(55,178	)
Weighted-average number of shares used in computing net loss per share, basic and diluted		19,179,299			12,004,489
Net loss per share, basic and diluted	$	(2.93	)	$	(4.60	)

Anti-dilutive Security not Included In Diluted per Share Calculations

	Year Ended December 31,
	2020		2019
Options to purchase common stock		2,355,615		1,577,541
Common stock warrants		85		7,857
Total		2,355,700		1,585,398

Nature of Operations - Additional Information (Detail)	12 Months Ended
Nature of Operations - Additional Information (Detail)	Dec. 31, 2020 Segment
Accounting Policies [Abstract]
Number of operating segment	1

Liquidity - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liquidity [Abstract]
Accumulated deficit	$ 314,761	$ 258,520
Cash, cash equivalents and short-term investments	81,900
Net loss	$ 56,241	$ 55,178

- Definition

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

+ References

+ Details

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 3,300
License and collaboration revenue	20,948
Research and Development Expense
Summary Of Significant Accounting Policies [Line Items]
Cost of collaboration revenue	$ 5,400
Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Computer equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture \| Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture \| Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
Leasehold improvements \| Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Leasehold improvements \| Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
AS 2016-02
Summary Of Significant Accounting Policies [Line Items]
Lease practical expedients	true

Assets and Liabilities Measured at Fair Value (Detail) - USD ($)
$ in Thousands

Dec. 31, 2020

Dec. 31, 2019

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

$ 81,897

$ 76,865

Money Market Funds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

^[1]

30,360

15,369

U.S. Government Agency Securities

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

37,837

^[2]

51,490

^[3]

Federal Agency Securities | Short-Term Investments

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

13,700

^[2]

10,006

^[3]

Fair Value, Inputs, Level 1

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

68,197

66,859

Fair Value, Inputs, Level 1 | Money Market Funds

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

^[1]

30,360

15,369

Fair Value, Inputs, Level 1 | U.S. Government Agency Securities

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

37,837

^[2]

51,490

^[3]

Fair Value, Inputs, Level 2

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

13,700

10,006

Fair Value, Inputs, Level 2 | Federal Agency Securities | Short-Term Investments

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Assets, fair value

$ 13,700

^[2]

$ 10,006

^[3]

[1]	Included in cash and cash equivalents on accompanying consolidated balance sheet.
[2]	Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities. $2.5 million of U.S. government agency securities are included in long-term investments on the accompanying consolidated balance sheets due to the maturity being more than 12 months.
[3]	Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities.

Assets and Liabilities Measured at Fair Value - Additional Information (Detail) $ in Millions	Dec. 31, 2020 USD ($)
Long Term Investments \| U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale, debt securities	$ 2.5

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 81,892	$ 76,831
Gross Unrealized Gains	5	34
Estimated Fair Value	81,897	76,865
Money Market Funds \| Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	30,360	15,369
Estimated Fair Value	30,360	15,369
U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	37,835	51,467
Gross Unrealized Gains	2	23
Estimated Fair Value	37,837	51,490
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	30,360	15,369
Short-Term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	48,994	61,496
Long-Term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	2,543
Federal Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	13,697	9,995
Gross Unrealized Gains	3	11
Estimated Fair Value	$ 13,700	$ 10,006

Financial Instruments - Additional Information (Detail)	12 Months Ended
Financial Instruments - Additional Information (Detail)	Dec. 31, 2020 USD ($)
Fair Value Disclosures [Abstract]
Material realized gains or losses on available-for-sale securities	$ 0
Available-for-sale debt securities current	49,000,000.0
Available-for-sale-debt securities noncurrent	$ 2,500,000

Schedule of Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Professional and consulting services	$ 3,979	$ 2,026
Manufacturing	2,238	4,320
Clinical	291	435
Other	235	250
Total other accrued liabilities	$ 6,743	$ 7,031

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Dec. 31, 2020 USD ($)
AGC Biologics, Inc \| Marzeptacog Alfa Activated and Dalcinonacog Alfa
Commitments And Contingencies Disclosure [Line Items]
Clinical trials	$ 11.2
Contractual obligation payments	2.3
Catalent Indiana, LLC. \| Dalcinonacog alfa.
Commitments And Contingencies Disclosure [Line Items]
Clinical trials	0.5
Clinical trials paid	$ 0.5

Related Parties - Additional Information (Detail) - Mosaic - USD ($) $ in Millions		12 Months Ended
	May 08, 2020	Dec. 31, 2020	Dec. 31, 2019	Jan. 10, 2020
Related Party Transaction [Line Items]
Expenses related to collaboration	$ 0.8
Maximum
Related Party Transaction [Line Items]
Milestone Payment Related To Regulatory And Clinical Development Events	$ 4.0
Research and Development Expense
Related Party Transaction [Line Items]
Other Research and Development Expense		$ 0.8
Intravitreal Anti-Complement Factor 3
Related Party Transaction [Line Items]
Payment related to collaboration		3.0
Collaboration Agreement
Related Party Transaction [Line Items]
Expenses related to collaboration		1.6
Collaboration Agreement \| Intravitreal Anti-Complement Factor 3
Related Party Transaction [Line Items]
Expenses related to collaboration		$ 1.3	$ 1.1
Biogen Collaboration \| Intravitreal Anti-Complement Factor 3
Related Party Transaction [Line Items]
Upfront license fee received from collaboration agreement				$ 15.0

Leases - Additional Information (Detail) - USD ($) $ in Thousands		12 Months Ended
	Jul. 17, 2020	Dec. 31, 2020	Dec. 31, 2019
Lessee Disclosure [Abstract]
Lease expiration date		Apr. 30, 2023
Lessee operating lease renewal term description		no stated renewal options
Operating lease not yet commenced description	commenced during the fourth quarter of 2020.
Operating lease term of contract	2 years 7 months 6 days
Total undiscounted lease payments	$ 500	$ 1,760
Operating lease expense		$ 700	$ 600

Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments (Detail)	Dec. 31, 2020	Dec. 31, 2019
Lessee Disclosure [Abstract]
Weighted-average remaining lease term	2 years 3 months 29 days	3 years 3 months 29 days
Weighted-average discount rate	5.70%	6.00%

Schedule of Maturity of Operating Lease Liabilities - (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jul. 17, 2020
Operating Lease Liabilities Payments Due [Abstract]
2021	$ 739
2022	762
2023	259
Total undiscounted lease payments	1,760	$ 500
Less: imputed interest	(116)
Total operating lease liability	$ 1,644

Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Lease Liabilities Payments Due [Abstract]
Cash paid for leases that were included in operating cash outflows	$ 602	$ 562

Stock Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jun. 11, 2020	Jun. 13, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Number of common stock available for future grant			1,255,302
Shares remaining outstanding			2,355,615	1,577,541	1,361,977
Total stock-based compensation			$ 3,627	$ 3,204
Employee Stock Option
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Unrecognized employee stock based compensation expense			$ 6,500
Unrecognized employee stock based compensation expense, period for recognition			2 years 7 months 17 days
2018 Omnibus Incentive Plan
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Increase in number of shares of common stock reserved for issuance	1,300,000
Common Stock, Capital Shares Reserved for Future Issuance	2,800,000
2018 Employee Stock Purchase Plan
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Number of common stock available for future grant			300,444
Maximum employee subscription rate		15.00%
Number of common stock authorized for issuance			359,545
Number of common stock stock issued			38,248
Proceeds from Issuance			$ 200
Total stock-based compensation			$ 100	$ 100
2018 Employee Stock Purchase Plan \| Maximum
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Percentage of fair market value of common stock		85.00%

Summary of Option Activity Under Company's Equity Incentive Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares Underlying Outstanding Options
Number of Shares Underlying Outstanding Options, Beginning Balance	1,577,541	1,361,977
Number of Shares Underlying Outstanding Options, Options granted	1,091,250	450,900
Number of Shares Underlying Outstanding Options, Options exercised	(44,605)	(41,219)
Number of Shares Underlying Outstanding Options, Options forfeited	(250,641)	(182,722)
Number of Shares Underlying Outstanding Options, Options expired	(17,930)	(11,395)
Number of Shares Underlying Outstanding Options, Ending Balance	2,355,615	1,577,541	1,361,977
Number of Shares Underlying Outstanding Options, Exercisable- December 31, 2020	1,113,791
Shares available to be granted - December 31, 2020	1,255,302
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning Balance	$ 10.85	$ 12.04
Weighted- Average Exercise Price, Options granted	6.26	7.85
Weighted- Average Exercise Price, Options exercised	5.04	4.57
Weighted- Average Exercise Price, Options forfeited	10.32	8.36
Weighted- Average Exercise Price, Options expired	51.12	96.49
Weighted- Average Exercise Price, Ending Balance	8.59	$ 10.85	$ 12.04
Weighted- Average Exercise Price, Exercisable - December 31, 2020	$ 10.45
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding Balance	7 years 11 months 15 days	8 years 1 month 24 days	8 years 8 months 15 days
Weighted Average Remaining Contractual Term, Exercisable - December 31, 2020	7 years 1 month 20 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding	$ 1,350	$ 2,294
Aggregate Intrinsic Value, Options exercised	116	159
Aggregate Intrinsic Value, Outstanding	1,337	$ 1,350	$ 2,294
Aggregate Intrinsic Value, Exercisable - December 31, 2020	$ 823

Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term (in years)	5 years 9 months 21 days	5 years 11 months 23 days
Risk-free interest rate	0.91%	2.35%
Dividend yield	0.00%	0.00%
Volatility	113.36%	90.81%
Weighted-average fair value of stock options granted	$ 5.20	$ 5.85

Summary of Stock-Based Compensation Recognized (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

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

Total stock-based compensation

$ 3,627

$ 3,204

Research and development

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

Total stock-based compensation

1,487

1,052

General and Administrative

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

Total stock-based compensation

^[1]

$ 2,140

$ 2,152

[1]	Included in general and administrative stock-based compensation for the years ended December 31, 2020 and 2019 is $0.3 million and $0.2 million in expense related to 51,056 shares and 24,235 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Summary of Stock-Based Compensation Recognized (Parenthetical) (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

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

Number of shares of common stock issued to certain board members in lieu of cash compensation

51,056

24,235

Total stock-based compensation

$ 3,627

$ 3,204

General and Administrative

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

Total stock-based compensation

^[1]

2,140

2,152

General and Administrative | Common Stock

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

Total stock-based compensation

$ 300

$ 200

[1]	Included in general and administrative stock-based compensation for the years ended December 31, 2020 and 2019 is $0.3 million and $0.2 million in expense related to 51,056 shares and 24,235 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Reconciliation of Statutory Federal Income Tax (benefit) Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax at statutory federal rate	(21.00%)	(21.00%)
State Tax (benefit)—net of federal benefit	(0.00%)	(0.06%)
Permanent differences	0.58%	0.43%
Tax credits	(12.26%)	(11.20%)
Derecognition due to Sec. 382 and 383 limitations	44.55%	(0.00%)
Change in valuation allowance	(12.25%)	31.20%
Other	0.38%	0.63%
Effective tax rate	0.00%	0.00%

Components of the Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Accruals and reserves	$ 1,095	$ 936
Net operating loss carry forwards	29,505	34,392
Tax credit carry forwards	7,789	9,945
Fixed and intangible assets	7	10
Valuation allowance	$ (38,396)	$ (45,283)

Income Taxes - Additional Information (Detail) - USD ($)		12 Months Ended
	Jun. 29, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2007
Income Tax [Line Items]
Increase (decrease) in valuation allowance		$ (6,900,000)	$ 17,200,000
Gross federal R&D tax credit-related deferred tax assets derecognized		15,200,000
Unrecognized tax benefit		2,955,000	1,871,000	$ 1,573,000
Tax-related penalties or interest recognized		0	0
Uncertain tax positions		0	$ 0
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		$ 140,400,000			$ 156,300,000
Net operating loss carryforwards expiration year		2037
Net operating loss carryforwards having indefinite life		$ 132,900,000
Tax credit carryforwards available to offset future federal tax liabilities		$ 5,000,000.0
Credit carryforward, expire period		Dec. 31, 2040
Net operating loss carryforward, derecognized		$ 32,800,000
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		$ 8,000,000.0
Net operating loss carryforwards expiration year		2032
Tax credit carryforwards available to offset future federal tax liabilities		$ 6,800,000
CALIFORNIA
Income Tax [Line Items]
Net operating loss carryforwards		70,800,000
Net operating loss carryforward, derecognized		$ 0
Maximum amount of tax offset per year	$ 5,000,000
Required Minimum Taxable Income	$ 1,000,000

Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Beginning Balance	$ 1,871	$ 1,573
Increase/(Decrease) of unrecognized tax benefits taken in prior years	(295)	45
Increase/(Decrease) of unrecognized tax benefits related to current year	1,379	253
Ending Balance	$ 2,955	$ 1,871

Collaborations - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended			12 Months Ended
	Dec. 18, 2019	Jan. 31, 2020	Dec. 31, 2018	Feb. 28, 2018	Dec. 31, 2020	Dec. 08, 2016
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					$ 20,948
License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					15,100
License \| Transfer of Exclusive License and Related Know-How
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					15,000
Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					100
Collaboration
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					5,848
Collaboration \| Reimbursable Out-of-Pocket and Personnel Costs Incurred Related to Research Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					5,800
Pfizer Inc \| Collaboration Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment				$ 1,000	0
Pfizer Inc \| Collaboration Agreement \| Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Contingent cash payments upon achievement of certain clinical, regulatory and commercial milestones						$ 17,500
ISU Abxis \| Amended and Restated License Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Regulatory and development milestone payment			$ 2,500		0
ISU Abxis \| Amended and Restated License Agreement \| Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment			19,500		0
Commercial milestone payments			$ 17,000		$ 0
Biogen \| License and Collaboration Agreement (the “Biogen Agreement”)
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Research services	30 months
Research services option to extend	12 months
Biogen \| Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Up-front payments received		$ 15,000
Biogen \| Exclusive License \| Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Development and sales milestone payments		$ 340,000

Detail of Interest and Other Income, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other Income And Expenses [Abstract]
Interest income	$ 561	$ 2,145
Miscellaneous income (expense)	659	(39)
Other	(91)	(7)
Total interest and other income, net	$ 1,129	$ 2,099

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jun. 30, 2020	Feb. 29, 2020	Dec. 31, 2020
Stockholders Equity Disclosure [Line Items]
Net proceeds from sale of common stock after deducting underwriting commissions and offering expenses payable	$ 28.0	$ 32.0
Underwriting discounts, commissions and offering expenses payable	$ 2.0	$ 2.5
Common Stock
Stockholders Equity Disclosure [Line Items]
Firm commitment underwritten public offering shares	4,615,384	5,307,692
Issuance of stock, shares			9,923,076
Common stock price, per share	$ 6.50	$ 6.50
Common Stock \| Overallotment Option
Stockholders Equity Disclosure [Line Items]
Issuance of stock, shares		692,307

Summary of Warrant Activity (Detail) - $ / shares	12 Months Ended
Summary of Warrant Activity (Detail) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Warrants And Rights Note Disclosure [Abstract]
Number of Shares Underlying Warrants, Outstanding	7,857	10,194
Number of Shares Underlying Warrants, Forfeited	(7,772)	(2,337)
Number of Shares Underlying Warrants, Outstanding	85	7,857
Warrants Outstanding, Weighted Average Exercise Price	$ 53.61	$ 155.73
Warrants Forfeited, Weighted Average Exercise Price	49.91	499.50
Warrants Outstanding, Weighted Average Exercise Price	$ 392.70	$ 53.61

Basic and Diluted Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (56,241)	$ (55,178)
Weighted-average number of shares used in computing net loss per share, basic and diluted	19,179,299	12,004,489
Net loss per share, basic and diluted	$ (2.93)	$ (4.60)

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
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+ Details

Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,355,700	1,585,398
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,355,615	1,577,541
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	85	7,857

Subsequent Event - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Common stock, shares issued		22,097,820	12,040,835
Scenario Forecast
Subsequent Event [Line Items]
Common stock, shares issued	9,185,000
Sale of stock price per share	$ 5.75
Net proceeds	$ 3.5
Underwriting discounts and offering expenses	$ 49.3
Underwriters' overallotment option \| Scenario Forecast
Subsequent Event [Line Items]
Common stock, shares issued	485,000