0001564590-22-029487 | 10-Q | XBRL Viewer

Nature of Operations and Liquidity

6 Months Ended

Jun. 30, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1.	Nature of Operations and Liquidity

Catalyst Biosciences, Inc. and its subsidiary (the “Company” or “Catalyst”) is a biopharmaceutical company with expertise in protease engineering. Prior to ceasing research and development activities in March 2022, the Company had several protease assets that may address unmet medical needs in disorders of the complement or coagulation systems. The Company is exploring several strategic alternatives to monetize the Company’s remaining assets and is focused on distributing its available cash, after paying or reserving for its obligations and liabilities, to stockholders. The Company is located in South San Francisco, California and operates in one segment.

On May 19, 2022, Catalyst entered into and closed on an asset purchase agreement with Vertex Pharmaceuticals Incorporated (“Vertex”), pursuant to which Vertex acquired Catalyst’s complement portfolio, including CB 2782-PEG and CB 4332, as well as its complement-related intellectual property including the ProTUNE^tm and ImmunoTUNE^tm platforms (See Note 12). After the transaction of its complement portfolio, Catalyst’s product candidates consist of the coagulation related assets marzeptacog alfa (activated) (“MarzAA”), dalcinonacog alfa (“DalcA”), and CB 2679d-GT. MarzAA is a SQ administered next generation engineered coagulation Factor VIIa (“FVIIa”) for the treatment of episodic bleeding and prophylaxis in subjects with rare bleeding disorders. DalcA is a next-generation SQ administered FIX. CB 2679d-GT is an AAV-based gene therapy construct harboring the DalcA sequence. Both MarzAA and DalcA have shown sustained efficacy and safety in mid-stage clinical trials and are available for partnering. CB 2679d-GT has obtained preclinical proof-of-concept and is also available for partnering.

The Company had a net income of $37.1 million for the six months ended June 30, 2022 and an accumulated deficit of $365.6 million as of June 30, 2022. As of June 30, 2022, the Company had $75.4 million of cash and cash equivalents. Its primary uses of cash are to fund operating expenses and general and administrative expenditures. The Company believes that its existing cash and cash equivalents as of June 30, 2022 will be sufficient to fund its cash requirements for at least the next 12 months from the date of the filing of this report. The Company will continue to evaluate the impact of the novel coronavirus disease (“COVID-19”) pandemic on its business, operations, and cash requirements.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2022

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

9.	Commitments and Contingencies

Manufacturing Agreements

The Company previously signed an agreement with AGC Biologics, Inc. (“AGC”) to perform certain manufacturing services related to the Company’s collaboration agreement with Biogen, which included firm work orders totaling $0.7 million. The payment obligations were fully paid off as of March 31, 2022, and Vertex assumed responsibility for further complement-related manufacturing in connection with the sale of the Company’s complement portfolio to Vertex (See Note 12). During the quarter ended June 30, 2022, the Company terminated its manufacturing agreement with AGC for Catalyst’s remaining programs and has no remaining obligations under the agreement as of June 30, 2022.

In July 2021, the Company entered into an agreement for the Company’s screening and natural history of disease clinical studies related to CFI deficiency, with total payments of up to $6.5 million. During the quarter ended June 30, 2022, the Company terminated this agreement and incurred $0.8 million for clinical trial services incurred prior to termination and reasonable wind-down expenses. As of June 30, 2022, the Company has no remaining obligations under this agreement.

On September 16, 2021, the Company signed a Manufacturing and Research and Development Studies Agreement to support the lyophilized drug product, CB 4332. The agreement covers analytical method qualification to support good manufacturing practices (“GMP”) manufacturing. The Company had firm work orders related to this agreement totaling $0.3 million. During the quarter ended June 30, 2022, the Company terminated this agreement and the payment obligations were fully paid off as of June 30, 2022.

Legal Proceedings

On June 15, 2022, certain Company stockholders who beneficially hold in the aggregate more than five percent (5%) of the Company’s common stock filed a lawsuit in Delaware Chancery Court, captioned JDS1, LLC v. Catalyst Biosciences, Inc., alleging that the Company violated Section 271 of the Delaware General Corporation Law and breach of fiduciary duty in connection with the Company’s asset sale to Vertex, as well as certain claims related to the alleged failure to disclose information related to the Vertex transaction. See Item 1 in Part II of this Form 10-Q for additional information. The Company believes these claims lack merit. However, should the Company not ultimately prevail, it is not possible to estimate the amount or range of potential loss, if any.

COVID-19

The current COVID-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting the Company’s employees and business operations. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s 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 Company’s ability to out-license any of its remaining assets.

Income Taxes - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($)
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	$ 185.9
Net operating loss carryforwards having indefinite life	87.1
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	$ 3.4
Net operating loss carryforwards expiration year	2033

Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2022

Investments All Other Investments [Abstract]

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

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

June 30, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	75,394	$	—	$	—	$	75,394
Total financial assets	$	75,394	$	—	$	—	$	75,394
Classified as:
Cash and cash equivalents							$	75,394
Total financial assets							$	75,394

December 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	44,347	$	—	$	—	$	44,347
U.S. government agency securities		2,504		—		—		2,504
Total financial assets	$	46,851	$	—	$	—	$	46,851
Classified as:
Cash and cash equivalents							$	44,347
Short-term investments								2,504
Total financial assets							$	46,851

Nature of Operations and Liquidity - Additional Information (Detail) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2022 USD ($) Segment	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Accounting Policies [Abstract]
Number of operating segment \| Segment					1
Net income (loss)	$ 51,632	$ (14,536)	$ (19,928)	$ (22,438)	$ 37,096	$ (42,366)
Accumulated deficit	365,598				365,598		$ 402,694
Cash and cash equivalents	$ 75,394				$ 75,394		$ 44,347

- 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

Net Income (Loss) Per Share Attributable to Common Stockholders - Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,512,163	3,236,677
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,512,078	3,236,592
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	85	85

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating Activities
Net income (loss)	$ 37,096	$ (42,366)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Stock-based compensation expense	861	2,009
Depreciation and amortization	180	90
Bad debt expense	200
Net gain on disposal of assets	(57,245)
Changes in operating assets and liabilities:
Accounts and other receivables	1,618	1,342
Prepaid and other current assets	2,197	(2,338)
Accounts payable	(5,382)	(4,091)
Accrued compensation and other accrued liabilities	(3,680)	663
Operating lease liability and right-of-use asset	41	157
Deferred revenue	(230)	55
Net cash flows used in operating activities	(24,344)	(44,479)
Investing Activities
Proceeds from maturities of short-term investments	2,504	38,632
Proceeds from the sale of property and equipment	447
Proceeds from the sale of complement portfolio to Vertex	55,000
Payment of transaction costs in connection with sale of complement portfolio to Vertex	(2,576)
Purchases of property and equipment		(347)
Net cash flows provided by investing activities	55,375	38,285
Financing Activities
Issuance of common stock for public offering, net of issuance costs		49,250
Issuance of common stock from stock grants and option exercises	16	205
Net cash flow provided by financing activities	16	49,455
Net increase in cash and cash equivalents	31,047	43,261
Cash and cash equivalents at beginning of the period	44,347	30,360
Cash and cash equivalents at end of the period	$ 75,394	73,621
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Right-of-use assets obtained in exchange for operating lease liabilities		$ 1,850

Lease (Tables)

6 Months Ended

Jun. 30, 2022

Lessee Disclosure [Abstract]

Summary of present value assumptions of lease payments [Table text block]

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

	June 30, 2022			December 31, 2021
Weighted-average remaining lease term	0.8 years			1.3 years
Weighted-average discount rate		4.8	%		4.8	%

Schedule of Maturity of Operating Lease Liabilities

The maturity of the Company’s operating lease liabilities as of June 30, 2022 were as follows (in thousands):

Year Ending December 31,	Amount
Remaining in 2022	$	1,029
2023		410
Total undiscounted lease payments		1,439
Less imputed interest		(24	)
Total operating lease liability	$	1,415

Schedule of Supplemental Cash Flow Information

Supplemental cash flow information related to operating leases was as follows (in thousands):

	Six Months Ended June 30,
	2022		2021
Cash paid for amounts included in the measurement of lease liabilities	$	1,015	$	680

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

Jun. 30, 2022

Dec. 31, 2021

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

Assets, fair value

$ 75,394

$ 46,851

U.S. Government Agency Securities

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

Assets, fair value

^[1]

2,504

Money Market Funds

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

Assets, fair value

^[2]

75,394

44,347

Fair Value, Inputs, Level 1

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

Assets, fair value

75,394

46,851

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

^[1]

2,504

Fair Value, Inputs, Level 1 | Money Market Funds

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

Assets, fair value

^[2]

$ 75,394

$ 44,347

[1]	Included in short-term investments on the accompanying condensed consolidated balance sheets and classified as available-for-sale debt securities
[2]	Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets.

Lease - Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments (Detail)	Jun. 30, 2022	Dec. 31, 2021
Lessee Disclosure [Abstract]
Weighted-average remaining lease term	9 months 18 days	1 year 3 months 18 days
Weighted-average discount rate	4.80%	4.80%

Stock Based Compensation - Additional Information (Detail) - shares	Jun. 09, 2021	Jun. 30, 2022
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Number of common stock available for future grant		3,013,716
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	2,500,000
Common Stock, Capital Shares Reserved for Future Issuance	5,300,000
2018 Omnibus Incentive Plan \| Performance-Based Stock Option Grants
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Issuance of option grants to purchase common stock shares		400,000

- Definition

Disclosure of information about share-based payment arrangement.

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+ Details

Stock Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

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 2018 Plan and related information:

	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)
Outstanding — December 31, 2021		2,603,630		$	7.70		7.46
Options granted		1,314,200		$	0.72
Options forfeited		(1,173,227	)	$	4.19
Options expired		(47,192	)	$	12.84
Outstanding — June 30, 2022		2,697,411		$	5.64		7.85
Exercisable — June 30, 2022		1,375,625		$	9.01

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:

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Employee Stock Options:
Risk-free rate		2.93	%		0.96	%		2.22	%		0.74	%
Expected term (in years)		6.0			5.7			6.0			6.0
Dividend yield	—			—			—			—
Volatility		91.82	%		92.79	%		91.63	%		93.64	%
Weighted-average fair value of stock options granted	$	0.87		$	3.37		$	0.55		$	4.45

Summary of Stock-Based Compensation Expense Recognized

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	83	$	394	$	211	$	763
General and administrative⁽¹⁾		263		589		650		1,246
Total stock-based compensation expense	$	346	$	983	$	861	$	2,009

(1)

Included in general and administrative stock-based compensation for the six months ended June 30, 2022 is stock-based compensation expense related to 32,684 shares of common stock issued to certain board members in lieu of their cash compensation. No shares of common stock were issued to board members for the three months ended June 30, 2022.

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2022

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 and liabilities measured at fair value on a recurring basis as of June 30, 2022 and December 31, 2021 (in thousands):

	June 30, 2022
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	75,394	$	—	$	—	$	75,394
Total financial assets	$	75,394	$	—	$	—	$	75,394

	December 31, 2021
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	44,347	$	—	$	—	$	44,347
U.S. government agency securities⁽²⁾		2,504		—		—		2,504
Total financial assets	$	46,851	$	—	$	—	$	46,851

(1)

Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets.

(2)

Included in short-term investments on the accompanying condensed consolidated balance sheets and classified as available-for-sale debt securities.

Stock Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Parenthetical) (Detail) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares of common stock issued to certain board members in lieu of cash compensation	0	32,684

Stock Based Compensation - Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail) - Employee Stock Option - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Risk-free rate	2.93%	0.96%	2.22%	0.74%
Expected term (in years)	6 years	5 years 8 months 12 days	6 years	6 years
Dividend yield	0.00%	0.00%	0.00%	0.00%
Volatility	91.82%	92.79%	91.63%	93.64%
Weighted-average fair value of stock options granted	$ 0.87	$ 3.37	$ 0.55	$ 4.45

Restructuring - Additional Information (Detail) $ in Thousands	1 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended
	May 31, 2022 USD ($)	Mar. 31, 2022 Employee	Nov. 30, 2021	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Restructuring Cost And Reserve [Line Items]
Percent of employees terminated			35.00%
Severance costs and expenses						$ 400
Charges related to write off of prepaid manufacturing cost						3,800
Restructuring liability						$ 200
Number of employees terminated \| Employee		22
Remaining number of full time employees \| Employee		5
Gain (loss) on disposal				$ 57,245	$ 57,245
Proceeds from the sale of complement portfolio to Vertex					55,000
Dren Bio, Inc. and Copia Scientific, LLC
Restructuring Cost And Reserve [Line Items]
Total consideration for sales agreements				400	400
Gain (loss) on disposal				$ (200)
Vertex Pharmaceuticals Incorporated
Restructuring Cost And Reserve [Line Items]
Gain (loss) on disposal	$ 57,400
Proceeds from the sale of complement portfolio to Vertex	60,000
Upfront payment received	55,000
Post closing indemnification obligation	$ 5,000
Transaction costs					2,600
Operating Expense
Restructuring Cost And Reserve [Line Items]
Severance and other charges					$ 1,000

Lease - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
Lease - Additional Information (Detail) - USD ($)	Mar. 31, 2022	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Lessee Lease Description [Line Items]
Lease expiration date				Apr. 30, 2023
Lessee operating lease renewal term description				no stated renewal options
Operating lease expense		$ 600,000	$ 400,000	$ 1,100,000	$ 600,000
Sublease Arrangement
Lessee Lease Description [Line Items]
Lease expiration date	Apr. 30, 2023
Lease Payments Receivable	$ 200,000
Sublease Income		$ 38,000		$ 38,000

Commitments and Contingencies - Additional Information (Detail) - USD ($)		3 Months Ended
	Jun. 15, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 16, 2021	Jul. 31, 2021
Commitments And Contingencies Disclosure [Line Items]
Percentage of common stock filed a lawsuit	5.00%
A G C Biologics Inc \| Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Remaining obligations		$ 0
A G C Biologics Inc \| Marzeptacog Alfa Activated And Dalcinonacog Alfa \| Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cost of Manufacturing Services			$ 700,000
Dalcinonacog Alfa \| Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Remaining obligations		0
Clinical trial services cost incurred on agreement termination		$ 800,000
Dalcinonacog Alfa \| Service Agreements \| Maximum
Commitments And Contingencies Disclosure [Line Items]
Cost of services as per agreement					$ 6,500,000
Catalent Indiana, LLC. \| Dalcinonacog alfa.
Commitments And Contingencies Disclosure [Line Items]
Firm work order supporting clinical trials				$ 300,000

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2020	$ 76,069	$ 22	$ 390,803	$ 5	$ (314,761)
Balance (in shares) at Dec. 31, 2020		22,097,820
Stock-based compensation expense	1,026		1,026
Stock-based compensation expense		10,149
Issuance of common stock from stock grants and option exercises	182		182
Issuance of common stock from stock grants and option exercises, shares		38,058
Issuance of common stock for public offering, net of issuance costs	49,250	$ 9	49,241
Issuance of common stock for public offering, net of issuance costs, shares		9,185,000
Net income (loss)	(22,438)				(22,438)
Balance at Mar. 31, 2021	104,089	$ 31	441,252	5	(337,199)
Balance (in shares) at Mar. 31, 2021		31,331,027
Balance at Dec. 31, 2020	76,069	$ 22	390,803	5	(314,761)
Balance (in shares) at Dec. 31, 2020		22,097,820
Unrealized loss on available-for-sale debt securities	(3)
Net income (loss)	(42,366)
Balance at Jun. 30, 2021	85,164	$ 31	442,258	2	(357,127)
Balance (in shares) at Jun. 30, 2021		31,349,740
Balance at Mar. 31, 2021	104,089	$ 31	441,252	5	(337,199)
Balance (in shares) at Mar. 31, 2021		31,331,027
Stock-based compensation expense	983		983
Stock-based compensation expense		13,713
Issuance of common stock from stock grants and option exercises	23		23
Issuance of common stock from stock grants and option exercises, shares		5,000
Unrealized loss on available-for-sale debt securities	(3)			(3)
Net income (loss)	(19,928)				(19,928)
Balance at Jun. 30, 2021	85,164	$ 31	442,258	$ 2	(357,127)
Balance (in shares) at Jun. 30, 2021		31,349,740
Balance at Dec. 31, 2021	41,089	$ 31	443,752		(402,694)
Balance (in shares) at Dec. 31, 2021		31,409,707
Stock-based compensation expense	515		515
Stock-based compensation expense		32,684
Issuance of common stock from stock grants and option exercises	16		16
Issuance of common stock from stock grants and option exercises, shares		34,662
Net income (loss)	(14,536)				(14,536)
Balance at Mar. 31, 2022	27,084	$ 31	444,283		(417,230)
Balance (in shares) at Mar. 31, 2022		31,477,053
Balance at Dec. 31, 2021	41,089	$ 31	443,752		(402,694)
Balance (in shares) at Dec. 31, 2021		31,409,707
Net income (loss)	37,096
Balance at Jun. 30, 2022	79,062	$ 31	444,629		(365,598)
Balance (in shares) at Jun. 30, 2022		31,477,053
Balance at Mar. 31, 2022	27,084	$ 31	444,283		(417,230)
Balance (in shares) at Mar. 31, 2022		31,477,053
Stock-based compensation expense	346		346
Net income (loss)	51,632				51,632
Balance at Jun. 30, 2022	$ 79,062	$ 31	$ 444,629		$ (365,598)
Balance (in shares) at Jun. 30, 2022		31,477,053

Subsequent Event

6 Months Ended

Jun. 30, 2022

Subsequent Events [Abstract]

Subsequent Event

13.	Subsequent Event

In August 2022, the Company entered into an agreement to terminate its license agreement for the use of laboratory facilities in South San Francisco, CA with a termination date of August 14, 2022.

Interest and Other Income (Expense), Net

6 Months Ended

Jun. 30, 2022

Other Income And Expenses [Abstract]

Interest and Other Income (Expense), Net

11.	Interest and Other Income (Expense), Net

The following table shows the detail of interest and other income (expense), net as follows (in thousands):

	Three Months Ended June 30,					Six Months Ended June 30,
	2022		2021			2022		2021
Interest income	$	85	$	11		$	87	$	28
Gain from extinguishment of liability		—	—				180	—
Other		17		(25	)		—		(42	)
Total interest and other income (expense), net	$	102	$	(14	)	$	267	$	(14	)

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance costs of issuance of common stock for public offering	$ 3,563

Financial Instruments

6 Months Ended

Jun. 30, 2022

Investments All Other Investments [Abstract]

Financial Instruments

4.	Financial Instruments

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

June 30, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	75,394	$	—	$	—	$	75,394
Total financial assets	$	75,394	$	—	$	—	$	75,394
Classified as:
Cash and cash equivalents							$	75,394
Total financial assets							$	75,394

December 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	44,347	$	—	$	—	$	44,347
U.S. government agency securities		2,504		—		—		2,504
Total financial assets	$	46,851	$	—	$	—	$	46,851
Classified as:
Cash and cash equivalents							$	44,347
Short-term investments								2,504
Total financial assets							$	46,851

There have been no material realized gains or losses on available-for-sale debt securities for the periods presented. As of June 30, 2022, the Company had no available-for-sale debt securities.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The Company’s condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s financial information. These interim results and cash flows for any interim period are not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any other future annual or interim period.

The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the consolidated financial statements filed with the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 (“Annual Report”).

Net Income (Loss) Per Share Attributable to Common Stockholders

Basic net income (loss) per share is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is based on the weighted average number of shares of common stock outstanding during the period, adjusted to include the assumed exercise of certain stock options and warrants using the treasury stock method. The calculation assumes that any proceeds that could be obtained upon exercise of options and warrants would be used to purchase common stock at the average market price during the period. Adjustments to the denominator are required to reflect the related dilutive shares.

Accounting Pronouncements Recently Adopted

In May 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options. The amendments in ASU 2021-04 provide guidance to clarify and reduce diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (for example, warrants) that remain equity classified after modification or exchange. The amendments in this ASU 2021-04 are effective for all entities for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years, with early adoption permitted, including interim periods within those fiscal years. The Company adopted ASU 2021-04 and related updates on January 1, 2022, and the adoption did not have a material impact on its condensed consolidated financial statements.

Income Taxes

6 Months Ended

Jun. 30, 2022

Income Tax Disclosure [Abstract]

Income Taxes

10.	Income Taxes

As of June 30, 2022, after consideration of certain limitations (see below), the Company had approximately $185.9 million federal and $3.4 million state net operating loss carryforwards ("NOL") available to reduce future taxable income which, if unused, will carry forward indefinitely for federal and will begin to expire in 2033 for state tax purposes. Contained in the federal NOL carryforward are $87.1 million that will not be immediately available to offset due to 382 limitations but will free up in varying amounts each year.

If the Company experiences a greater than 50 percentage point aggregate change in ownership over a three-year period (a Section 382 ownership change), utilization of its pre-change NOL carry forwards 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 on December 21, 2007, August 20, 2015, April 13, 2017, February 15, 2018, and February 18, 2020. The ability of the Company to use its remaining NOL and tax credit carry forwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership.

- Definition

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

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-Subparagraph (b)
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Paragraph 1
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

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-Paragraph 2
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+ Details

Financial Instruments - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($)
Fair Value Disclosures [Abstract]
Material realized gains or losses on available-for-sale securities	$ 0
Available-for-sale debt securities current	$ 0

Interest and Other Income (Expense), Net - Detail of Interest and Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Other Income And Expenses [Abstract]
Interest income	$ 85	$ 11	$ 87	$ 28
Gain from extinguishment of liability			180
Other	17	(25)		(42)
Total interest and other income (expense), net	$ 102	$ (14)	$ 267	$ (14)

Financial Instruments - Cash Equivalents and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 75,394	$ 46,851
Estimated Fair Value	75,394	46,851
Money Market Funds \| Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	75,394	44,347
Estimated Fair Value	75,394	44,347
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	$ 75,394	44,347
U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		2,504
Estimated Fair Value		2,504
Short-Term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value		$ 2,504

Net Income (Loss) Per Share Attributable to Common Stockholders - Basic and Diluted Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income (loss) attributable to common stockholders	$ 51,632	$ (19,928)	$ 37,096	$ (42,366)
Weighted-average number of shares used in computing net loss per share, basic	31,477,053	31,348,602	31,466,630	29,875,202
Effect of dilutive stock options	5,872		2,936
Weighted-average number of shares used in computing net loss per share, diluted	31,482,925	31,348,602	31,469,566	29,875,202
Net income (loss) per share, basic	$ 1.64	$ (0.64)	$ 1.18	$ (1.42)
Net income (loss) per share, diluted	$ 1.64	$ (0.64)	$ 1.18	$ (1.42)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- 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
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+ Details

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating expenses (income):
Research and development	$ 1,871	$ 15,389	$ 11,574	$ 32,402
General and administrative	3,844	4,518	8,838	9,930
Gain on disposal of assets, net	(57,245)		(57,245)
Total operating expenses (income)	(51,530)	21,046	(36,035)	44,951
Income (loss) from operations	51,530	(19,914)	36,829	(42,352)
Interest and other income (expense), net	102	(14)	267	(14)
Net income (loss)	$ 51,632	$ (19,928)	$ 37,096	$ (42,366)
Net income (loss) per share attributable to common stockholders, basic	$ 1.64	$ (0.64)	$ 1.18	$ (1.42)
Net income (loss) per share attributable to common stockholders, diluted	$ 1.64	$ (0.64)	$ 1.18	$ (1.42)
Shares used to compute net income (loss) per share attributable to common stockholders, basic	31,477,053	31,348,602	31,466,630	29,875,202
Shares used to compute net income (loss) per share attributable to common stockholders, diluted	31,482,925	31,348,602	31,469,566	29,875,202
Collaboration
Revenue:
License and collaboration revenue		$ 1,132	$ 794	$ 2,599
Cost of collaboration
Operating expenses (income):
Cost of license and collaboration		$ 1,139	$ 798	$ 2,619

Interest and Other Income (Expense), Net (Tables)

6 Months Ended

Jun. 30, 2022

Other Income And Expenses [Abstract]

Detail of Interest and Other Income (Expense), Net

The following table shows the detail of interest and other income (expense), net as follows (in thousands):

	Three Months Ended June 30,					Six Months Ended June 30,
	2022		2021			2022		2021
Interest income	$	85	$	11		$	87	$	28
Gain from extinguishment of liability		—	—				180	—
Other		17		(25	)		—		(42	)
Total interest and other income (expense), net	$	102	$	(14	)	$	267	$	(14	)

Net Income (Loss) per Share Attributable to Common Stockholders (Tables)

6 Months Ended

Jun. 30, 2022

Earnings Per Share [Abstract]

Anti-dilutive Security not Included in Diluted per Share Calculations

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	Six Months Ended June 30,
	2022		2021
Options to purchase common stock		2,512,078		3,236,592
Common stock warrants		85		85
Total		2,512,163		3,236,677

Basic and Diluted Net Income (Loss) Per Common Share

The following table sets forth the computation of the basic and diluted net income (loss) per common share as follows (in thousands, except share and per share data):

	Three Months Ended June 30,					Six Months Ended June 30,
	2022		2021			2022		2021
Net income (loss) attributable to common stockholders	$	51,632	$	(19,928	)	$	37,096	$	(42,366	)
Weighted-average number of shares used in computing net loss per share, basic		31,477,053		31,348,602			31,466,630		29,875,202
Effect of dilutive stock options		5,872		—			2,936		—
Weighted-average number of shares used in computing net loss per share, diluted		31,482,925		31,348,602			31,469,566		29,875,202
Net income (loss) per share, basic	$	1.64	$	(0.64	)	$	1.18	$	(1.42	)
Net income (loss) per share, diluted	$	1.64	$	(0.64	)	$	1.18	$	(1.42	)

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s financial information. These interim results and cash flows for any interim period are not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any other future annual or interim period. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the consolidated financial statements filed with the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 (“Annual Report”).
Net Income (Loss) Per Share Attributable to Common Stockholders	Net Income (Loss) Per Share Attributable to Common Stockholders Basic net income (loss) per share is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is based on the weighted average number of shares of common stock outstanding during the period, adjusted to include the assumed exercise of certain stock options and warrants using the treasury stock method. The calculation assumes that any proceeds that could be obtained upon exercise of options and warrants would be used to purchase common stock at the average market price during the period. Adjustments to the denominator are required to reflect the related dilutive shares.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted In May 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options. The amendments in ASU 2021-04 provide guidance to clarify and reduce diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (for example, warrants) that remain equity classified after modification or exchange. The amendments in this ASU 2021-04 are effective for all entities for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years, with early adoption permitted, including interim periods within those fiscal years. The Company adopted ASU 2021-04 and related updates on January 1, 2022, and the adoption did not have a material impact on its condensed consolidated financial statements.

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2022	Dec. 31, 2021
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	31,477,053	31,409,707
Common stock, shares outstanding	31,477,053	31,409,707

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

3 Months Ended

6 Months Ended

Jun. 30, 2022

Jun. 30, 2021

Jun. 30, 2022

Jun. 30, 2021

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

Total stock-based compensation expense

$ 346

$ 983

$ 861

$ 2,009

Research and development

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

Total stock-based compensation expense

394

211

763

General and Administrative

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

Total stock-based compensation expense

^[1]

$ 263

$ 589

$ 650

$ 1,246

[1]

Net Income (Loss) per Share Attributable to Common Stockholders

6 Months Ended

Jun. 30, 2022

Earnings Per Share [Abstract]

Net Income (Loss) per Share Attributable to Common Stockholders

8.	Net Income (Loss) Per Share Attributable to Common Stockholders

The dilutive effect of outstanding stock options and warrants is calculated using the treasury stock method. Stock options and warrants are anti-dilutive and excluded from the diluted net income (loss) per share calculation if the exercise price exceeds the average market price of the common shares.

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	Six Months Ended June 30,
	2022		2021
Options to purchase common stock		2,512,078		3,236,592
Common stock warrants		85		85
Total		2,512,163		3,236,677

The following table sets forth the computation of the basic and diluted net income (loss) per common share as follows (in thousands, except share and per share data):

	Three Months Ended June 30,					Six Months Ended June 30,
	2022		2021			2022		2021
Net income (loss) attributable to common stockholders	$	51,632	$	(19,928	)	$	37,096	$	(42,366	)
Weighted-average number of shares used in computing net loss per share, basic		31,477,053		31,348,602			31,466,630		29,875,202
Effect of dilutive stock options		5,872		—			2,936		—
Weighted-average number of shares used in computing net loss per share, diluted		31,482,925		31,348,602			31,469,566		29,875,202
Net income (loss) per share, basic	$	1.64	$	(0.64	)	$	1.18	$	(1.42	)
Net income (loss) per share, diluted	$	1.64	$	(0.64	)	$	1.18	$	(1.42	)

Lease

6 Months Ended

Jun. 30, 2022

Lessee Disclosure [Abstract]

Lease

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.

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.

In March 2022, the Company entered into a sublease agreement for one of its leased facilities that commenced in April 2022. Under the terms of the sublease agreement, the Company will receive $0.2 million in base lease payments over the term of the sublease, which ends in April 2023. For the three and six months ended June 30, 2022, the Company recognized sublease income of $38,000.

For the three and six months ended June 30, 2022, the Company’s operating lease expense was $0.6 million and $1.1 million, respectively. For the three and six months ended June 30, 2021, the Company’s operating lease expense was $0.4 million and $0.6 million, respectively.

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

	June 30, 2022			December 31, 2021
Weighted-average remaining lease term	0.8 years			1.3 years
Weighted-average discount rate		4.8	%		4.8	%

The maturity of the Company’s operating lease liabilities as of June 30, 2022 were as follows (in thousands):

Year Ending December 31,	Amount
Remaining in 2022	$	1,029
2023		410
Total undiscounted lease payments		1,439
Less imputed interest		(24	)
Total operating lease liability	$	1,415

Supplemental cash flow information related to operating leases was as follows (in thousands):

	Six Months Ended June 30,
	2022		2021
Cash paid for amounts included in the measurement of lease liabilities	$	1,015	$	680

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2022	Jul. 29, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	CBIO
Entity Registrant Name	Catalyst Biosciences, Inc.
Entity Central Index Key	0001124105
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		31,477,053
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	000-51173
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
Entity Interactive Data Current	Yes
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock

Subsequent Events - Additional Information (Detail)	Aug. 15, 2022
Subsequent Event
Subsequent Event [Line Items]
License agreement termination date	Aug. 14, 2022

Collaborations - Additional Information (Detail) - USD ($)		1 Months Ended			3 Months Ended		6 Months Ended
	May 08, 2020	Jun. 30, 2022	Jan. 31, 2020	Dec. 31, 2018	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Research and development					$ 1,871,000	$ 15,389,000	$ 11,574,000	$ 32,402,000
Deferred revenue, recognized							200,000
Mosaic Biosciences Inc \| Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment related to regulatory and clinical development events	$ 4,000,000.0
ISU Abxis \| Amended and Restated License Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Regulatory and development milestone payment				$ 2,500,000			0
ISU Abxis \| Maximum \| Amended and Restated License Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment				19,500,000			0
Commercial milestone payments				$ 17,000,000.0			0
Biogen \| Collaboration
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Research and development						$ 1,100,000	700,000	$ 2,600,000
Biogen \| Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Up-front payments received			$ 15,000,000.0
Biogen \| Termination Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Forgiveness of accounts receivable, net		$ 600,000			600,000		$ 600,000
Payments to cash		$ 10,000
Biogen \| Termination Agreement \| General and Administrative
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Settlement expense					$ 600,000
Biogen \| Maximum \| Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Development and sales milestone payments			$ 340,000,000.0

Lease - Schedule of Maturity of Operating Lease Liabilities (Detail) $ in Thousands	Jun. 30, 2022 USD ($)
Operating Lease Liabilities Payments Due [Abstract]
Remaining in 2022	$ 1,029
2023	410
Total undiscounted lease payments	1,439
Less imputed interest	(24)
Total operating lease liability	$ 1,415

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 51,632	$ (19,928)	$ 37,096	$ (42,366)
Other comprehensive loss:
Unrealized loss on available-for-sale debt securities		(3)		(3)
Total comprehensive income (loss)	$ 51,632	$ (19,931)	$ 37,096	$ (42,369)

- Definition

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

+ References

+ Details

Fair Value Measurements

6 Months Ended

Jun. 30, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

For a description of the fair value hierarchy and the Company’s fair value methodology, see “Part II - Item 8 - Financial Statements and Supplementary Data - Note 3 – Summary of Significant Accounting Policies” in the Company’s Annual Report. There were no significant changes in these methodologies during the six months ended June 30, 2022.

The following tables present the fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of June 30, 2022 and December 31, 2021 (in thousands):

	June 30, 2022
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	75,394	$	—	$	—	$	75,394
Total financial assets	$	75,394	$	—	$	—	$	75,394

	December 31, 2021
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds⁽¹⁾	$	44,347	$	—	$	—	$	44,347
U.S. government agency securities⁽²⁾		2,504		—		—		2,504
Total financial assets	$	46,851	$	—	$	—	$	46,851

(1)

Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets.

(2)

Included in short-term investments on the accompanying condensed consolidated balance sheets and classified as available-for-sale debt securities.

The carrying amounts of cash and cash equivalents, accounts and other receivables, 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

Stock Based Compensation

6 Months Ended

Jun. 30, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Compensation

6.	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 (the “Committee”) of the Board, subject to stockholder approval. The 2018 Plan became effective on June 13, 2018. On June 9, 2021, 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 2,500,000 to a total of 5,300,000 shares. The amendment became effective immediately upon stockholder approval.

Performance-Based Stock Option Grant

In June 2022, the Committee approved the issuance of an option grant to purchase 400,000 shares of common stock to the Chief Executive Officer pursuant to the 2018 Plan, which will vest upon (a) the achievement of a specified performance goal and (b) the grantees’ continued employment during the service period. For the six months ended June 30, 2022, no expense has been recognized related to this award.

The following table summarizes stock option activity under the Company’s 2018 Plan and related information:

	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)
Outstanding — December 31, 2021		2,603,630		$	7.70		7.46
Options granted		1,314,200		$	0.72
Options forfeited		(1,173,227	)	$	4.19
Options expired		(47,192	)	$	12.84
Outstanding — June 30, 2022		2,697,411		$	5.64		7.85
Exercisable — June 30, 2022		1,375,625		$	9.01

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 relevant historical data, 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 relevant 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:

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Employee Stock Options:
Risk-free rate		2.93	%		0.96	%		2.22	%		0.74	%
Expected term (in years)		6.0			5.7			6.0			6.0
Dividend yield	—			—			—			—
Volatility		91.82	%		92.79	%		91.63	%		93.64	%
Weighted-average fair value of stock options granted	$	0.87		$	3.37		$	0.55		$	4.45

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	83	$	394	$	211	$	763
General and administrative⁽¹⁾		263		589		650		1,246
Total stock-based compensation expense	$	346	$	983	$	861	$	2,009

(1)

As of June 30, 2022, 3,013,716 shares of common stock were available for future grant.

Collaborations

6 Months Ended

Jun. 30, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaborations

7.	Collaborations

Mosaic

In October 2017, the Company entered into a strategic research collaboration with Mosaic Biosciences (“Mosaic”) to develop intravitreal anti-complement factor 3 (C3) products for the treatment of dry Age-related Macular Degeneration (AMD) and other retinal diseases. The Company subsequently amended this agreement in December 2018, December 2019 and May 2020.

Under the as amended Mosaic collaboration agreement, 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 prior 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.

As a result of the sale of the Company’s complement portfolio, including CB 2782-PEG and other assets, to Vertex in May 2022, the Mosaic collaboration agreement was transferred to Vertex (see Note 12).

ISU Abxis

In December 2018, the Company entered into an amended and restated license agreement with ISU Abxis (the “A&R 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 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 June 30, 2022, 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 performed certain pre-clinical and manufacturing activities (“Research Services”), and Biogen was solely responsible for funding the pre-clinical and manufacturing activities and performing IND-enabling activities, worldwide clinical development, and commercialization.

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 was eligible to receive development milestones and sales milestones of up to $340.0 million. In addition, the Company was 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 also received 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.

In March 2022, the Company received written notice from Biogen declaring intent to terminate the Biogen Agreement which was effective as of May 2022. As a result of the termination, Biogen no longer has the Exclusive License to develop, manufacture and commercialize CB 2782-PEG and other anti-C3 proteases for potential treatment of dry AMD and other disorders. In March 2022, Biogen returned full rights to CB 2782-PEG.

In June 2022, Biogen and the Company reached an agreement to resolve the outstanding obligations and monetary disputes between the parties. The Company agreed to forgive approximately $0.6 million of accounts receivable, net due from Biogen and to pay Biogen $10,000 in cash. This resulted in the Company recognizing a $0.6 million settlement expense for the three months ended June 30, 2022, which is included in general and administrative operating expenses in the condensed consolidated statements of operations.

The Company recognized $0.7 million of research and development expense as cost of collaboration revenue for the six months ended June 30, 2022. The Company recognized $1.1 million and $2.6 million for the three and six months ended June 30, 2021, respectively, of research and development expense as cost of collaboration revenue related to the Biogen Agreement. Research and development expenses were reimbursed by Biogen in accordance with the agreement.

For the six months ended June 30, 2022, the Company recognized $0.2 million of revenue from the beginning of period deferred revenue balance.

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 75,394	$ 44,347
Short-term investments		2,504
Accounts and other receivables, net	5,000	1,818
Prepaid and other current assets	914	2,807
Total current assets	81,308	51,476
Other assets, noncurrent	168	472
Right-of-use assets	1,733	2,744
Property and equipment, net	164	970
Total assets	83,373	55,662
Current liabilities:
Accounts payable	1,037	6,419
Accrued compensation	911	1,467
Deferred revenue		230
Other accrued liabilities	948	4,072
Operating lease liability	1,415	1,977
Total current liabilities	4,311	14,165
Operating lease liability, noncurrent		408
Total liabilities	4,311	14,573
Commitments and contingencies (Note 9)
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; 31,477,053 and 31,409,707 shares issued and outstanding at June 30, 2022 and December 31, 2021, respectively	31	31
Additional paid-in capital	444,629	443,752
Accumulated deficit	(365,598)	(402,694)
Total stockholders’ equity	79,062	41,089
Total liabilities and stockholders’ equity	$ 83,373	$ 55,662

Stock Based Compensation - Summary of Option Activity Under Company's 2018 Plan (Detail) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Number of Shares Underlying Outstanding Options
Number of Shares Underlying Outstanding Options, Beginning Balance	2,603,630
Number of Shares Underlying Outstanding Options, Options granted	1,314,200
Number of Shares Underlying Outstanding Options, Options forfeited	(1,173,227)
Number of Shares Underlying Outstanding Options, Options expired	(47,192)
Number of Shares Underlying Outstanding Options, Ending Balance	2,697,411	2,603,630
Number of Shares Underlying Outstanding Options, Exercisable - June 30, 2022	1,375,625
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning Balance	$ 7.70
Weighted- Average Exercise Price, Options granted	0.72
Weighted- Average Exercise Price, Options forfeited	4.19
Weighted- Average Exercise Price, Options expired	12.84
Weighted- Average Exercise Price, Ending Balance	5.64	$ 7.70
Weighted- Average Exercise Price, Exercisable - June 30, 2022	$ 9.01
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding Balance	7 years 10 months 6 days	7 years 5 months 15 days

Restructuring

6 Months Ended

Jun. 30, 2022

Restructuring And Related Activities [Abstract]

Restructuring

12.	Restructuring

Reduction-in-Force

In November 2021, the Board approved a restructuring of its business based on its decision to stop the clinical development of MarzAA and focus solely on its complement programs and protease medicines platform. The restructuring included a reduction-in-force whereby approximately 35% of employees were terminated. During the year ended December 31, 2021, the Company recorded charges of $0.4 million related to one-time severance costs and related expenses in connection with the workforce reduction, and charges of $3.8 million related to the write-off of prepaid manufacturing costs that will no longer be used for the clinical development of MarzAA. The remaining restructuring liability of $0.2 million was paid during the second quarter of 2022.

In March 2022, the Board approved a further reduction of its workforce as part of its restructuring plan whereby 22 full-time employees were terminated. Following this reduction, the Company had five full-time employees remaining. During the quarter ended March 31, 2022, the Company recorded additional charges of $1.0 million for severance and other costs related to the reduction-in-force, recognized as an operating expense within the consolidated statements of operations, which the Company paid in the second quarter of 2022.

Sale of Assets

During the quarter ended June 30, 2022, the Company entered into sales agreements with Dren Bio, Inc. and Copia Scientific, LLC, pursuant to which the Company sold various lab equipment, consumables, and furniture and fixtures for total consideration of $0.4 million. The Company recorded a loss on disposal of $0.2 million, which is included in gain on disposal of assets, net in the condensed consolidated statements of operations.

In May 2022, the Company entered into an asset purchase agreement with Vertex, pursuant to which Vertex purchased the Company’s complement portfolio, including CB 2782-PEG and CB 4332, as well as its complement-related intellectual property including the ProTUNE^TM and ImmunoTUNE^TM platforms for $60.0 million in cash consideration. Cash of $55.0 million was received upfront in May 2022 and the remaining $5.0 million will be paid one year after the closing upon satisfaction of certain post-closing indemnification obligations. The hold-back amount is recorded within accounts and other receivables, net on the condensed consolidated balance sheet. There were no carrying amounts associated with the intellectual property sold to Vertex, and, therefore, the Company recorded a gain of $57.4 million related to the disposal, net of $2.6 million of transaction costs, which is included in gain on disposal of assets, net in the condensed consolidated statements of operations.

Lease - Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating Lease Liabilities Payments Due [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 1,015	$ 680