Gyre Therapeutics (GYRE) 10-Q 26 Oct 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 20, 2023
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
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		37,978,142
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	12770 High Bluff Drive
Entity Address, Address Line Two	Suite 150
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	650
Local Phone Number	266-8674
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
Former Address [Member]
Document Information [Line Items]
Entity Address, Address Line One	611 Gateway Blvd.
Entity Address, Address Line Two	Suite 120
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 2,228	$ 21,666
Accounts and other receivables		5,000
Prepaid insurance	1,169	1,136
Prepaid and other current assets	535	404
Total current assets	5,132	28,206
Other assets, noncurrent	168	168
Right-of-use assets		66
Property and equipment, net		4
Total assets	9,964	28,444
Current liabilities:
Accounts payable	158	194
Accrued compensation	708	2,582
Other accrued liabilities	917	1,452
Dividends payable		7,558
CVR derivative liability		5,000
Operating lease liability		38
Total current liabilities	1,783	16,824
CVR derivative liability, noncurrent	4,664
Total liabilities	6,447	16,824
Commitments and Contingencies (Note 8)
Stockholders’ deficit:
Convertible preferred stock, $0.001 par value, 123,418 shares authorized; 12,340 and 0 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	33,309
Common stock, $0.001 par value, 100,000,000 shares authorized, 37,978,142 and 37,756,574 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	37	37
Additional paid-in capital	384,895	389,210
Accumulated deficit	(414,724)	(410,936)
Total stockholders' equity (deficit)	3,517	(21,689)
Total liabilities, redeemable convertible preferred stock, and stockholders' equity (deficit)	9,964	28,444
Redeemable Convertible Preferred Stock
Current liabilities:
Redeemable convertible preferred stock, $0.001 par value, 123,418 shares authorized; 0 and 12,340 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively		$ 33,309
GC Biopharma Corp
Current assets:
Long-term receivable from GCBP	4,664
GNI
Current assets:
Other receivables from GNI	$ 1,200

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Preferred stock par value per share	$ 0.001
Preferred stock shares authorized	5,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	37,978,142	37,756,574
Common stock, shares outstanding	37,978,142	37,756,574
Redeemable Convertible Preferred Stock
Temporary equity,par value	$ 0.001	$ 0.001
Temporary equity, shares authorized	123,418	123,418
Temporary equity, shares outstanding	0	12,340
Temporary equity, shares issued	0	12,340
Preferred stock shares authorized	123,418
Convertible Preferred Stock
Preferred stock par value per share	$ 0.001	$ 0.001
Preferred stock shares authorized	123,418	123,418
Preferred stock shares issued	12,340	0
Preferred Stock, Shares Outstanding	12,340	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses (income):
Research and development	$ 415,000	$ 803,000	$ 1,321,000	$ 12,377,000
General and administrative	2,408,000	4,363,000	8,603,000	13,201,000
GNI cost-sharing reimbursement	(1,200,000)		(1,200,000)
Gain on disposal of assets, net			(4,736,000)	(57,245,000)
Total operating expenses (income)	1,623,000	5,166,000	3,988,000	(30,869,000)
Income (loss) from operations	(1,623,000)	(5,166,000)	(3,988,000)	31,663,000
Interest and other income, net	47,000	282,000	216,000	549,000
Income (loss) before income taxes	(1,576,000)	(4,884,000)	(3,772,000)	32,212,000
Income tax expenses	0	0	16,000	0
Net income (loss) and comprehensive income (loss)	$ (1,576,000)	$ (4,884,000)	$ (3,788,000)	$ 32,212,000
Net income (loss) per share attributable to common stockholders, basic	$ (0.04)	$ (0.16)	$ (0.1)	$ 1.02
Net income (loss) per share attributable to common stockholders, diluted	$ (0.04)	$ (0.16)	$ (0.1)	$ 1.02
Shares used to compute net income (loss) per share attributable to common stockholders, basic	37,976,764	31,484,542	37,845,900	31,472,666
Shares used to compute net income (loss) per share attributable to common stockholders, diluted	37,976,764	31,484,542	37,845,900	31,605,834
Cash dividends paid per common share		$ 1.43	$ 0.24	$ 1.43
Contingent Value Rights Agreement
Operating expenses (income):
Cash dividends paid per common share	$ 0.05		$ 0.17
Collaboration
Revenue:
License and collaboration revenue				$ 794,000
Cost of collaboration
Operating expenses (income):
Cost of license and collaboration				$ 798,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Redeemable Preferred Stock	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit
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, shares					32,684
Issuance of common stock from stock grants	16					16
Issuance of common stock from stock grants, 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)	32,212
Balance at Sep. 30, 2022	29,375				$ 31	399,826	(370,482)
Balance (in shares) at Sep. 30, 2022					31,490,053
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
Stock-based compensation expense	224					224
Issuance of common stock from stock grants	4					4
Issuance of common stock from stock grants, shares					13,000
Cash dividends paid	(45,031)					(45,031)
Net income (loss)	(4,884)						(4,884)
Balance at Sep. 30, 2022	29,375				$ 31	399,826	(370,482)
Balance (in shares) at Sep. 30, 2022					31,490,053
Balance at Dec. 31, 2022	(21,689)				$ 37	389,210	(410,936)
Temporary equity, Balance (in shares) at Dec. 31, 2022		12,340
Temporary equity, Balance at Dec. 31, 2022		$ 33,309
Balance (in shares) at Dec. 31, 2022					37,756,574
Stock-based compensation expense	210					210
Issuance of common stock from stock grants	2					2
Issuance of common stock from stock grants, shares					3,251
Cash dividends paid	(206)					(206)
CVR derivative liability	(4,530)					(4,530)
Net income (loss)	260						260
Balance at Mar. 31, 2023	(25,953)				$ 37	384,686	(410,676)
Temporary Equity, Balance (in shares) at Mar. 31, 2023		12,340
Temporary Equity, Balance at Mar. 31, 2023		$ 33,309
Balance (in shares) at Mar. 31, 2023					37,759,825
Balance at Dec. 31, 2022	$ (21,689)				$ 37	389,210	(410,936)
Temporary equity, Balance (in shares) at Dec. 31, 2022		12,340
Temporary equity, Balance at Dec. 31, 2022		$ 33,309
Balance (in shares) at Dec. 31, 2022					37,756,574
Issuance of common stock from option exercises, shares	215,067
CVR derivative liability	$ (4,530)
Net income (loss)	(3,788)
Balance at Sep. 30, 2023	3,517			$ 33,309	$ 37	384,895	(414,724)
Temporary Equity, Balance (in shares) at Sep. 30, 2023		0
Balance (in shares) at Sep. 30, 2023				12,340	37,978,142
Balance at Mar. 31, 2023	(25,953)				$ 37	384,686	(410,676)
Temporary equity, Balance (in shares) at Mar. 31, 2023		12,340
Temporary equity, Balance at Mar. 31, 2023		$ 33,309
Balance (in shares) at Mar. 31, 2023					37,759,825
Stock-based compensation expense	89					89
Issuance of common stock from option exercises	22					22
Issuance of common stock from option exercises, shares					215,067
Issuance of preferred stock for stock dividends, shares			37,975
Net income (loss)	(2,472)						(2,472)
Balance at Jun. 30, 2023	(28,314)				$ 37	384,797	(413,148)
Temporary Equity, Balance (in shares) at Jun. 30, 2023		12,340	37,975
Temporary Equity, Balance at Jun. 30, 2023		$ 33,309
Balance (in shares) at Jun. 30, 2023					37,974,892
Stock-based compensation expense	98					98
Elimination and redemption of preferred stock, shares			37,975
Issuance of common stock from stock grants, shares					3,250
Temporary equity, Reclassification of preferred stock to permanent equity		$ (33,309)
Temporary equity, Reclassification of preferred stock to permanent equity, shares		(12,340)
Reclassification of preferred stock to permanent equity	33,309			$ 33,309
Reclassification of preferred stock to permanent equity, shares				12,340
Net income (loss)	(1,576)						(1,576)
Balance at Sep. 30, 2023	$ 3,517			$ 33,309	$ 37	$ 384,895	$ (414,724)
Temporary Equity, Balance (in shares) at Sep. 30, 2023		0
Balance (in shares) at Sep. 30, 2023				12,340	37,978,142

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) - $ / shares					3 Months Ended		9 Months Ended
	Aug. 21, 2023	Jun. 05, 2023	Mar. 08, 2023	Jan. 12, 2023	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Cash dividends paid per common share				$ 0.24		$ 1.43	$ 0.24	$ 1.43
Contingent Value Rights Agreement
Cash dividends paid per common share	$ 0.05	$ 0.11	$ 0.01		$ 0.01

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities
Net income (loss)	$ (3,788)	$ 32,212
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Stock-based compensation expense	397	1,085
Depreciation and amortization	4	220
Change in fair value of long-term receivables	(134)
Change in fair value of derivative liabilities	134
Bad debt expense		200
Loss on lease termination		110
Net gain on disposal of assets	(4,736)	(57,245)
Changes in operating assets and liabilities:
Accounts and other receivables		1,618
Other receivables from GNI	(1,200)
Prepaid insurance	(33)
Prepaid and other current assets	(131)	993
Accounts payable	(36)	(6,378)
Accrued compensation and other accrued liabilities	(2,409)	(4,317)
Operating lease liability and right-of-use asset	28	111
Deferred revenue		(230)
Net cash used in operating activities	(11,904)	(31,621)
Investing Activities
Proceeds from maturities of short-term investments		2,504
Proceeds from the sale of property and equipment		447
Proceeds from the sale of complement portfolio to Vertex	5,000	55,000
Payment of transaction costs in connection with the sale of complement portfolio to Vertex		(2,576)
Proceeds from the sale of legacy rare bleeding disorder program to GCBP	1,000
Payment of transaction costs in connection with the sale of legacy rare bleeding disorder program to GCBP	(794)
Net cash provided by investing activities	5,206	55,375
Financing Activities
Payment of dividends	(12,764)	(45,031)
Issuance of common stock from stock grants and option exercises	24	20
Net cash used in financing activities	(12,740)	(45,011)
Net decrease in cash and cash equivalents	(19,438)	(21,257)
Cash and cash equivalents at beginning of the period	21,666	44,347
Cash and cash equivalents at end of the period	2,228	$ 23,090
Supplemental Disclosure on Non-Cash Investing and Financing Activities:
CVR derivative liability	$ 4,530

Nature of Operations and Liquid

Nature of Operations and Liquidity	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations and Liquidity	1. Nature of Operations and Liquidity Catalyst Biosciences, Inc. and its subsidiary (the “Company” or “Catalyst”) was 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 were designed to address unmet medical needs in disorders of the complement or coagulation systems. The Company was located in South San Francisco, California during the quarter ended September 30, 2023 and operates in one segment. As discussed below, the Company recently completed a purchase agreement to acquire a clinical-stage drug candidate for the treatment of NASH (nonalcoholic steatohepatitis, a severe form of nonalcoholic fatty liver disease). Concurrent with this purchase agreement, the Company entered into a separate business combination agreement to acquire an indirect controlling interest in a China-based pharmaceutical company. On May 19, 2022, Catalyst entered into and closed on an asset purchase agreement with Vertex Pharmaceuticals Inc. (“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 11, Restructuring. On February 27, 2023, Catalyst entered into and closed on an asset purchase agreement with GC Biopharma Corp. (“GCBP”), pursuant to which GCBP acquired Catalyst’s legacy rare bleeding disorder program, including the coagulation related assets marzeptacog alfa (activated) (“MarzAA”), dalcinonacog alfa (“DalcA”), and CB-2679d-GT. See Note 11, Restructuring. Reclassifications Prepaid insurance has been reclassified out of prepaid and other current assets to conform to the current period presentation in the accompanying notes. F351 Asset Acquisition and Series X Redeemable Convertible Preferred Stock On December 26, 2022, the Company executed and closed an Asset Purchase Agreement, which was amended on March 29, 2023 (the “F351 Agreement”), with GNI Group Ltd. (“GNI Japan”) and GNI Hong Kong Limited ("GNI Hong Kong") to purchase all of the assets and intellectual property rights primarily related to the proprietary Hydronidone compound (collectively, the “F351 Assets”), other than such assets and intellectual property rights located in the People’s Republic of China ("PRC"). At the closing of the agreement on December 26, 2022, the Company paid $ 35.0 million in the form of 6,266,521 shares of Catalyst common stock and 12,340 shares of newly designated Series X redeemable convertible preferred stock (“Catalyst Convertible Preferred Stock”). Each share of Catalyst Convertible Preferred Stock is convertible into 10,000 shares of common stock, subject to stockholder approval under Nasdaq rules and subject to a beneficial ownership conversion blocker. For additional information, see Note 3, F351 Asset Acquisition . At its 2023 Annual Meeting of Stockholders on August 29, 2023, the Company's stockholders approved the conversion of the Catalyst Convertible Preferred Stock into shares of the Company's common stock in accordance with Nasdaq Listing Rule 5635(a) (the "Conversion Proposal"), and approved an amendment to the Company's certificate of incorporation to authorize sufficient shares of common stock for the conversion of the Catalyst Convertible Preferred Stock issued pursuant to the F351 Agreement. Following stockholder approval of the Conversion Proposal, each share of Catalyst Convertible Preferred Stock is convertible at the option of the holder into 10,000 shares of the Company's common stock, subject to a beneficial ownership conversion blocker. Prior to stockholder approval of the Conversion Proposal, the terms of the Catalyst Convertible Preferred Stock included a cash redemption feature. Upon stockholder approval of the Conversion Proposal, the cash redemption feature was eliminated and the Catalyst Convertible Preferred Stock was reclassified to stockholders' equity. Business Combination Agreement Concurrent with the F351 Asset acquisition, the Company signed a definitive agreement, dated as of December 26, 2022, and as amended on March 29, 2023 and August 30, 2023 , with GNI Japan, GNI Hong Kong, GNI USA, Inc. ("GNI USA"), Continent Pharmaceuticals Inc. and Shanghai Genomics, Inc. (collectively, “GNI”) and other minority stockholders to acquire an indirect controlling interest in Beijing Continent Pharmaceutical Co., Ltd. (“BC”), a commercial-stage pharmaceutical company based in China and a majority-owned subsidiary of GNI, in exchange for newly issued shares of common stock (the “Business Combination Agreement”). The closing of the transactions under the Business Combination Agreement are subject to stockholder approval and certain customary closing conditions. Catalyst stockholders approved the transactions under the Business Combination Agreement at the 2023 Annual Meeting of Stockholders on August 29, 2023, however, as of September 30, 2023 the transactions had not closed. On October 20, 2023, BC received approval from the China Securities Regulatory Commission ("CSRC") with respect to the business combination pursuant to the Business Combination Agreement. Catalyst and GNI anticipate the business combination will be completed by the Outside Date (as defined in the Business Combination Agreement). For additional information, see Note 8, Commitments and Contingencies . Contingent Value Rights Agreement Pursuant to the Business Combination Agreement, on December 26, 2022, Catalyst and the Rights Agent (as defined therein) executed a contingent value rights agreement, as amended on March 29, 2023 (the “CVR Agreement”), pursuant to which each holder of Catalyst common stock as of January 5, 2023, excluding GNI (the “CVR Holders”), received one contractual contingent value right (a “CVR”) issued by the Company for each share of Catalyst common stock held by such holder. Each CVR entitles the holder thereof to receive certain cash payments in the future. For additional information, see Note 8, Commitments and Contingencies . Liquidity On January 12, 2023 , the Company paid a one-time cash dividend of $ 0.24 per share to the CVR Holders. The aggregate amount of the special dividend payment was approximately $ 7.6 million. On March 8, 2023, the Company distributed the net cash proceeds received from the GCBP asset sale of $ 0.2 million, or $ 0.01 per share, to the CVR Holders. See Note 11, Restructuring , for additional information regarding this distribution. On June 5, 2023, the Company distributed the net cash proceeds received from the Vertex hold-back amount of $ 3.5 million, or $ 0.11 per share, to the CVR Holders. See Note 11, Restructuring , for additional information regarding this distribution. On August 21, 2023, the Company distributed the remaining net cash proceeds received from the Vertex hold-back amount of $ 1.5 million, or $ 0.05 per share, to the CVR Holders. See Note 11, Restructuring , for additional information regarding this distribution. The Company had a net loss of $ 3.8 million for the nine months ended September 30, 2023. As of September 30, 2023, the Company had an accumulated deficit of $ 414.7 million and cash and cash equivalents of $ 2.2 million. Its primary uses of cash are to fund operating expenses and general and administrative expenditures. As part of the Business Combination Agreement, GNI agreed to share certain ongoing operating expenses incurred by the Company until the Business Combination Agreement closes. See Note 12, Related Parties , for additional information regarding this arrangement. The actual amount and timing of the cost sharing payments from GNI is outside of the control of the Company. Given the uncertainties related to the pending Business Combination Agreement, there is substantial doubt about the Company's ability to continue as a going concern for at least 12 months following the issuance of these condensed consolidated financial statements. The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The condensed consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
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 condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated 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 consolidated financial information. These condensed consolidated results of operations and cash flows for any interim period are not necessarily indicative of the results to be expected for the year ending December 31, 2023, 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, 2022 (the “Annual Report”). Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance for doubtful accounts, long-term receivable, CVR derivative liabilities, 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 June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments . 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 is effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, using a modified retrospective approach. The Company adopted ASU 2016-13 and related updates as of January 1, 2023 and the adoption did not have a material impact on its condensed consolidated financial statements. Long-Term Receivable The Company determined that the hold-back from the GCBP asset sale in February 2023 qualified as a long-term receivable. The receivable is considered a loan held for investment since the Company has the intent and ability to hold to maturity. Catalyst has elected to account for the receivable under the fair value option method of accounting and any changes in fair value are recorded in interest and other income, net on the condensed consolidated statement of operations and comprehensive income (loss). Refer to Note 4, Fair Value Measurements and Note 11, Restructuring , for additional information regarding the long-term receivable and GCBP asset sale. Net Income (Loss) per Share Attributable to Common Stockholders The Company calculates basic and diluted net income (loss) per share attributable to common stockholders in conformity with the two-class method required for participating securities. The Catalyst Convertible Preferred Stock contractually entitles the holders of such shares to participate in dividends, but such participation is contingent upon the completion of the transactions under the Business Combination Agreement with GNI. As a result, the Catalyst Convertible Preferred Stock is excluded from the basic EPS calculation, as these shares are not participating securities until the Business Combination Agreement with GNI closes. During periods of loss, the Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. Basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Participating securities are excluded from the basic weighted average common shares outstanding. Diluted net income (loss) per share attributable to common stockholders is based on the weighted average number of common shares outstanding during the period, including potential dilutive common shares. For purposes of this calculation, outstanding stock options and warrants are considered potential dilutive common shares. The calculation of diluted EPS also considers the effect of the Catalyst Convertible Preferred Stock since conversion is no longer contingent after the stockholders approved the Conversion Proposal on August 29, 2023.

F351 Asset Acquisition

F351 Asset Acquisition	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
F351 Asset Acquisition	3. F351 Asset Acquisition On December 26, 2022, the Company acquired the F351 Assets from GNI in accordance with the terms of the F351 Agreement as discussed in Note 1, Nature of Operations and Liquidity . Under the terms of the F351 Agreement, the Company issued 6,266,521 shares of common stock and 12,340 shares of Catalyst Convertible Preferred Stock. The Company concluded that the F351 acquisition was not the acquisition of a business, as substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable asset, the intellectual property rights (outside of the PRC) to a clinical stage drug candidate for the treatment of liver fibrosis, or the F351 Assets. The acquisition cost of $ 35.4 million attributable to the acquired in-process research and development ("IPR&D") was expensed in the Company's consolidated statements of operations for the year ended December 31, 2022 since the acquired IPR&D had no alternative future use, as determined by the Company in accordance with GAAP.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. 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 nine months ended September 30, 2023. The following tables present the fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 ( in thousands ): September 30, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 2,228 $ — $ — $ 2,228 Long-term receivable from GCBP — — 4,664 4,664 Total financial assets $ 2,228 $ — $ 4,664 $ 6,892 Financial liabilities: CVR derivative liability, noncurrent $ — $ — $ 4,664 $ 4,664 Total financial liabilities $ — $ — $ 4,664 $ 4,664 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 21,666 $ — $ — $ 21,666 Total financial assets $ 21,666 $ — $ — $ 21,666 Financial liabilities: CVR derivative liability $ — $ — $ 5,000 $ 5,000 Total financial liabilities $ — $ — $ 5,000 $ 5,000 (1) Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets. The carrying amounts of accounts and other receivables, other receivables from GNI, accounts payable, and accrued liabilities approximate their fair values due to the short-term maturity of these instruments. Derivative Liabilities and Long-term Receivables The CVR derivative liability relates to the CVR Agreement executed in connection with the Business Combination Agreement. The fair value of this derivative liability is based on significant unobservable inputs, which represent Level 3 measurements within the fair value hierarchy. The estimated fair value of the CVR liability was determined based on the anticipated amount and timing of projected cash flows to be received from Vertex pursuant to the Vertex asset purchase agreement. The CVR liability was initially recorded at $ 5.0 million at issuance on December 26, 2022 and in May 2023, the Company received a $ 5.0 million hold-back payment from Vertex, which was distributed, net of expenses and a reserve for potential tax liabilities, to the CVR Holders. There was no change in the estimated fair value of the CVR liability prior to the distribution. The long-term receivable and the corresponding CVR derivative liability, noncurrent relate to the asset purchase agreement with GCBP. The fair value of this long-term receivable and derivative liability is based on significant unobservable inputs, which represent Level 3 measurements within the fair value hierarchy. The estimated fair value of the long-term receivable and CVR derivative liability, noncurrent was determined based on the anticipated amount and timing of projected cash flows to be received from GCBP pursuant to the GCBP asset purchase agreement discounted to their present values using an estimated discount rate of 5.05 %. As of September 30, 2023, the Company expects to receive a $ 5.0 million hold-back payment from GCBP in the first quarter of 2025, which will be distributed, net of expenses, to the CVR Holders. The change in fair value of the long-term receivable from GCBP and the corresponding CVR derivative liability, noncurrent was recorded in interest and other income, net on the condensed consolidated statement of operations and comprehensive income (loss). The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial assets and liabilities ( in thousands ): Long-term receivable CVR derivative from GCBP liability, noncurrent Balance at December 31, 2022 $ — $ — Additions in the period 4,530 4,530 Changes in fair value 134 134 Balance at September 30, 2023 $ 4,664 $ 4,664

Lease

Lease	9 Months Ended
	Sep. 30, 2023
Lessee Disclosure [Abstract]
Lease	5. Lease The Company leased office space for its prior corporate headquarters located in South San Francisco, CA. The lease term expired on April 30, 2023 , and since then the Company had a month-to-month lease for its prior corporate headquarters. The month-to-month lease ended on September 30, 2023. In March 2022, the Company entered into a sublease agreement for its leased facility that commenced in April 2022 . Under the terms of the sublease agreement, the Company received $ 0.2 million in base lease payments over the term of the sublease, which ended in April 2023 . No sublease income was recognized for the three months ended September 30, 2023. For the nine months ended September 30, 2023, the Company recognized sublease income of $ 0.1 million. For the three and nine months ended September 30, 2022, the Company recognized sublease income of $ 38,000 and $ 0.1 million, respectively. No significant operating lease expense was recorded for the three months ended September 30, 2023. For the nine months ended September 30, 2023, the Company’s operating lease expense was $ 0.1 million. For the three and nine months ended September 30, 2022, the Company’s operating lease expense was $ 0.4 million and $ 1.5 million, respectively. Since the operating lease expired on April 30, 2023, the present value assumptions for the current period were not applicable. The present value assumptions used in calculating the present value of the lease payments were as follows: September 30, 2023 December 31, 2022 Weighted-average remaining lease term n/a 0.3 years Weighted-average discount rate n/a 4.3 % Supplemental cash flow information related to operating leases was as follows (in thousands) : Nine Months Ended September 30, 2023 2022 Cash paid for amounts included in the measurement of lease liabilities $ 39 $ 1,422

Stock Based Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [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. After the option modification (as discussed below), the number of shares of common stock reserved for issuance under the 2018 Plan increased to a total of 31,456,403 . As of September 30, 2023, there were 25,521,867 shares of common stock available for future grant. Performance-Based Stock Option Grants In June 2022, the Committee approved the issuance of an option grant to purchase 400,000 shares ( 2,457,917 shares after the option modification discussed below) 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 grantee’s continued employment during the service period. During the three months ended March 31, 2023, this award was cancelled. Prior to cancellation, no expense has been recognized related to this award and no options have vested. Special Cash Dividend On January 12, 2023 , the Company paid a special, one-time cash dividend of $ 7.6 million (or $ 0.24 per share) to the CVR Holders. The Company determined, in accordance with the adjustment provision of the 2018 Plan, that the special cash dividend was unusual and non-recurring and that appropriate adjustment to the stock options to purchase shares of the Company’s common stock outstanding under the 2018 Plan was required. The Company treated this adjustment as a modification to the original stock option grants because the terms of the agreements were modified in order to preserve the value of the option awards after a large non-recurring cash dividend. These options were amended to decrease the exercise price and increase the number of shares subject to the stock option on a proportionate basis. No incremental value was provided to the option holders as a result of the modification and no additional compensation cost was recorded by the Company. The following table summarizes stock option activity under the Company’s 2018 Plan and related information: Number of Shares Weighted- Weighted- Outstanding — December 31, 2022 8,678,767 $ 1.42 7.47 Options granted (1) 14,008,093 $ 0.86 Options exercised ( 215,067 ) $ 0.10 Options forfeited and cancelled (1) ( 14,210,119 ) $ 0.91 Options expired ( 14,729 ) $ 34.33 Outstanding — September 30, 2023 8,246,945 $ 1.32 5.43 Exercisable — September 30, 2023 7,609,393 $ 1.37 (1) Includes options that were cancelled and re-granted as part of the option modification from the special cash dividend, as further discussed above. 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 only options granted during the nine months ended September 30, 2023 were as a result of the option modification. Since no new stock options were granted during the three and nine months ended September 30, 2023, all weighted-average assumptions for the period were not applicable. The fair value of employee stock options was estimated using the following weighted-average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Employee Stock Options: Risk-free interest rate n/a 3.02 % n/a 2.25 % Expected term (in years) n/a 6.1 n/a 6.0 Dividend yield n/a — n/a — Volatility n/a 91.61 % n/a 91.63 % Weighted-average fair value of stock options granted n/a $ 1.34 n/a $ 0.58 Total stock-based compensation expense recognized was as follows ( in thousands ): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Research and development $ — $ 78 $ 67 $ 289 General and administrative (1) 98 146 330 796 Total stock-based compensation expense $ 98 $ 224 $ 397 $ 1,085 (1) No shares of common stock were issued to Board members for the three and nine months ended September 30, 2023.

Net Income (Loss) per Share Att

Net Income (Loss) per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Income (Loss) per Share Attributable to Common Stockholders	7. Net Income (Loss) per Share Attributable to Common Stockholders Potentially dilutive securities are excluded from the calculation of diluted net income (loss) per share attributable to common stockholders if their inclusion is anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: Nine Months Ended September 30, 2023 2022 Catalyst Convertible Preferred Stock (1) 123,400,000 — Options to purchase common stock 8,246,945 7,034,805 Total 131,646,945 7,034,805 (1) Shown as common stock equivalents The following is a reconciliation of the numerator (net income or loss) and denominator (number of shares) used in the calculation of basic and diluted net income (loss) per share attributable to common stockholders (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Numerator Net income (loss) $ ( 1,576 ) $ ( 4,884 ) $ ( 3,788 ) $ 32,212 Denominator Weighted-average number of shares used in 37,976,764 31,484,542 37,845,900 31,472,666 Effect of dilutive stock options — — — 133,168 Weighted-average number of shares used in 37,976,764 31,484,542 37,845,900 31,605,834 Net income (loss) per share available for common $ ( 0.04 ) $ ( 0.16 ) $ ( 0.10 ) $ 1.02 Net income (loss) per share available for common $ ( 0.04 ) $ ( 0.16 ) $ ( 0.10 ) $ 1.02

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies As of September 30, 2023 and December 31, 2022, the Company had cash deposited in certain financial institutions in excess of federally insured levels. The Company regularly monitors the financial stability of these financial institutions and believes that it is not exposed to any significant credit risk in cash and cash equivalents. However, in March and April 2023, certain U.S. government banking regulators took steps to intervene in the operations of certain financial institutions due to liquidity concerns, which caused general heightened uncertainties in financial markets. While these events have not had a material direct impact on the Company’s operations, if further liquidity and financial stability concerns arise with respect to banks and financial institutions, either nationally or in specific regions, the Company’s ability to access cash or enter into new financing arrangements may be threatened, which could have a material adverse effect on its business, financial condition and results of operations. Business Combination Agreement Concurrent with the F351 Asset acquisition, the Company entered into the Business Combination Agreement with GNI and other minority stockholders (“Sellers” and each a “Seller”) to acquire an indirect controlling interest in BC, a commercial-stage pharmaceutical company based in China and majority-owned subsidiary of GNI, in exchange for newly issued shares of Catalyst common stock. The closing of the transactions under the Business Combination Agreement are subject to stockholder approval and certain customary closing conditions. Catalyst stockholders approved the transactions under the Business Combination Agreement at the 2023 Annual Meeting of Stockholders on August 29, 2023, however, as of September 30, 2023 the transactions had not closed. On October 20, 2023, BC received approval from the CSRC with respect to the business combination pursuant to the Business Combination Agreement. Catalyst and GNI anticipate the business combination will be completed by the Outside Date (as defined in the Business Combination Agreement). Once the transaction closes, the Company will issue at closing a total of up to 1,110,776,224 shares of Catalyst common stock for an indirect controlling interest in BC. Each Seller may elect to be issued Catalyst Convertible Preferred Stock in lieu of the Company’s common stock. The Business Combination Agreement contains certain termination rights, including the right for Catalyst to terminate the Business Combination Agreement to enter into a definitive agreement for a superior proposal. Upon termination of the Business Combination Agreement under specified circumstances, the Company may be required to pay a termination fee of $ 2.0 million and either party, as the case may be, may be required to reimburse the other party for reasonable out-of-pocket fees and expenses incurred by such party in connection with the Business Combination Agreement, up to a maximum amount of $ 2.0 million. Contingent Value Rights Agreement Pursuant to the Business Combination Agreement, on December 26, 2022, Catalyst and the Rights Agent (as defined therein) executed the CVR Agreement, as amended on March 29, 2023, pursuant to which the CVR Holders received one contractual CVR issued by the Company, subject to and in accordance with the terms and conditions of the CVR Agreement, for each share of Catalyst common stock held by such holder. Each CVR entitles the holder thereof to receive (i) certain cash payments from the net proceeds related to the disposition of the Company’s legacy assets (MarzAA, DalcA, and CB 2679d-GT), (ii) 100 % of the excess cash (net of all current or contingent liabilities, including transaction-related expenses) retained by the Company in excess of $ 1.0 million as of the closing date of the transactions under the Business Combination Agreement, (iii) 100 % of the amount actually received by the Company, net of expenses, pursuant to the Vertex asset purchase agreement and (iv) 100 % of the excess, by which the preapproved costs to manage, negotiate, settle and finalize certain third party claims exceed the costs actually incurred with respect to such claims. The CVRs are not transferable, except in certain limited circumstances as provided for in the CVR Agreement, will not be certificated or evidenced by any instrument, and will not be registered with the SEC or listed for trading on any exchange. In December 2022, the Company recorded a $ 5.0 million short-term CVR derivative liability related to the Vertex asset purchase agreement. On June 5, 2023, the Company distributed the net cash proceeds received from Vertex of $ 3.5 million, which reflected the amount received from Vertex less expenses and a reserve for potential tax liabilities, to the CVR Holders. On August 21, 2023, the Company distributed the remaining net cash proceeds received from Vertex of $ 1.5 million to the CVR Holders. Refer to Note 4, Fair Value Measurements and Note 11, Restructuring , for additional information regarding the CVR derivative liability and Vertex hold-back payment. In February 2023, the Company sold its legacy rare bleeding disorder program to GCBP. As a result, the Company distributed the net cash proceeds received from the GCBP asset sale of $ 0.2 million to the CVR Holders as well as recorded a $ 4.5 million long-term CVR derivative liability for the future distribution of the hold-back amount to be received in May 2025. Refer to Note 4, Fair Value Measurements and Note 11, Restructuring, for additional information regarding the CVR derivative liability and GCBP asset sale. As of September 30, 2023, no liability was recorded for the CVR payment related to the distribution of the excess cash retained by the Company in excess of $ 1.0 million as of the closing date of the Business Combination Agreement. Cost Sharing and Agency Agreement with GNI On April 13, 2023, the Company entered into a Cost Sharing and Agency Agreement with GNI, whereas GNI will pay for certain costs related to the development of the F351 Assets in the U.S. and the Company will make certain repayments under different circumstances. As of September 30, 2023, GNI had paid $ 0.3 million of the reimbursable development costs related to the F351 Assets, and the Company had a future repayment obligation of up to $ 0.3 million, which was included in other accrued liabilities on the balance sheet. Refer to Note 12, Related Parties for additional information regarding the Cost Sharing and Agency Agreement with GNI. Manufacturing Agreements On April 18, 2023, the Company entered into two separate agreements to support the F351 Assets acquired from GNI. One agreement will cover analytical method process familiarization and validation to support good manufacturing practices (“GMP”) manufacturing, and the other agreement will cover non-GMP manufacturing services and clinical supply batch GMP manufacturing of the F351 Assets, with total payments of up to $ 0.3 million and $ 0.2 million, respectively. The Company can terminate these agreements at any time upon 90 days written notice. Upon termination, the Company will be responsible to pay for services incurred prior to termination and any non-cancellable obligations in connection with such services.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes During the three months ended September 30, 2023, no income tax expense was recorded. During the nine months ended September 30, 2023, the Company recorded an income tax expense of $ 16,000 . No income tax expense was recognized during the three and nine months ended September 30, 2022. The Company recorded no income tax benefits for the net operating losses incurred or for the research and development tax credits generated in each period due to its uncertainty of realizing a benefit from those items. All of the Company’s operating losses since inception have been generated in the United States. As of September 30, 2023, after consideration of certain limitations (see below), the Company had approximately $ 193.7 million federal and $ 3.7 million state net operating loss carryforwards (“NOL”) available to reduce future taxable income which, if unused, the majority will carry forward indefinitely for federal and will begin to expire in 2034 for state tax purposes. 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 on December 31, 2007, August 20, 2015, April 13, 2017, February 15, 2018, February 18, 2020, and December 26, 2022. 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.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Stockholders' Equity (Deficit)	10. Stockholders ’ Equity (Deficit) The Company is authorized to issue 5,000,000 shares of preferred stock with a par value of $ 0.001 per share under its restated certificate of incorporation. The Company has designated 123,418 shares to be Catalyst Convertible Preferred Stock and in June 2023, designated 161,160 shares as Series Y redeemable preferred stock (“Series Y Preferred Stock”). On August 29, 2023, the Company's stockholders approved the adoption of an amendment to Catalyst's restated certificate of incorporation to increase the number of authorized shares of common stock from 100,000,000 shares to 400,000,000 shares. Redeemable Preferred Stock On June 20, 2023, the Board declared a dividend of one one-thousandth of a share of Series Y Preferred Stock, par value $ 0.001 per share, for each outstanding share of common stock to stockholders of record as of June 30, 2023. This Series Y Preferred Stock entitled its holder to 250,000 votes per share exclusively on the vote for the proposal to approve the reverse stock split (as defined in the Series Y Preferred Stock Certificate of Designation). The Company held its 2023 Annual Meeting of Stockholders on August 29, 2023, which included the reverse stock split as a proposal to be voted on at the meeting. All shares of Series Y Preferred Stock that were not present to vote on the reverse stock split were redeemed by the Company (the “Initial Redemption”). Any outstanding shares of Series Y Preferred Stock that were not redeemed pursuant to an Initial Redemption would be redeemed in whole, but not in part, (i) if such redemption is ordered by the Board in its sole discretion, automatically and effective on such time and date specified by the Board in its sole discretion or (ii) automatically upon the effectiveness of the amendment to the certificate of incorporation implementing the reverse stock split. At the August 29, 2023 meeting of the Company's stockholders, the holders of 25,256 shares of Series Y Preferred Stock were represented in person or by proxy and their shares were redeemed thereafter. Immediately prior to the meeting, all 135,904 shares of Series Y Preferred Stock that were not represented were redeemed. On August 31, 2023, the Company filed a Certificate of Elimination of Series Y Preferred Stock with the Secretary of State of the State of Delaware, which, effective immediately upon filing, eliminated all matters set forth in the Certificate of Designation of Series Y Preferred Stock filed with the Secretary of State of the State of Delaware on June 20, 2023.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Restructuring	11. Restructuring 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. 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 condensed consolidated statements of operations and comprehensive income (loss), which the Company paid during 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 a total consideration of $ 0.4 million. The Company recorded a loss on disposal of $ 0.2 million during the nine months ended September 30, 2022, which is included in gain on disposal of assets, net in the condensed consolidated statements of operations and comprehensive income (loss). 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 was received in May 2023 upon satisfaction of certain post-closing indemnification obligations. The hold-back amount was initially recorded within accounts and other receivables on the condensed consolidated balance sheet. In June 2023, the Company distributed $ 3.5 million, which reflected the hold-back amount received from Vertex less expenses and a reserve for potential tax liabilities, to the CVR Holders pursuant to the CVR Agreement. In August 2023, the Company distributed the remaining $ 1.5 million initially withheld as a reserve for potential tax liabilities to the CVR Holders pursuant to the CVR Agreement, see Note 8, Commitments and Contingencies . 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 during the second quarter of 2022. In February 2023, Catalyst entered into an asset purchase agreement with GCBP, pursuant to which GCBP acquired the Company’s legacy rare bleeding disorders programs, including MarzAA, DalcA and CB-2679d-GT, for $ 6.0 million in cash consideration. Cash of $ 1.0 million was received upfront in February 2023 and the remaining $ 5.0 million will be paid two years after the closing upon satisfaction of certain post-closing indemnification obligations. The hold-back amount is recorded as a long-term receivable on the condensed consolidated balance sheet. In March 2023, the Company distributed the net cash proceeds received upfront of $ 0.2 million to the CVR Holders. Once received, the remaining net proceeds, net of expenses, from the hold-back amount will be distributed to the CVR Holders pursuant to the CVR Agreement, see Note 8, Commitments and Contingencies . There were no carrying amounts associated with the intellectual property sold to GCBP, and, therefore, Catalyst recorded a gain of $ 4.7 million related to the disposal, net of $ 0.8 million of transaction costs, which is included in gain on disposal of assets, net in the condensed consolidated statements of operations and comprehensive income (loss) for the nine months ended September 30, 2023.

Related Parties

Related Parties	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Related Parties	12. Related Parties Following the closing of the F351 Agreement on December 26, 2022, GNI owned 100 % of the Catalyst Convertible Preferred Stock as well as 16.6 % and 16.5 % of Catalyst common stock outstanding as of December 31, 2022 and September 30, 2023, respectively. Overall, GNI owned 80.5 % and 80.3 % of the outstanding shares of capital stock of the Company, on an as converted basis, as of December 31, 2022 and September 30, 2023, respectively. In addition, Ying Luo and Thomas Eastling became directors of the Company. They serve as a director, representative executive officer, President and Chief Executive Officer, and an outside member, respectively, of GNI Japan, a greater than 5 % stockholder of the Company. Dr. Luo also serves as a director of the board and President of GNI USA. GNI is considered a related party of the Company. On April 13, 2023, the Company entered into a Cost Sharing and Agency Agreement with GNI. Under the Cost Sharing and Agency Agreement, GNI will pay for certain costs related to the development of the F351 Assets in the U.S. incurred from December 26, 2022 until the Business Combination Agreement closes. Following the closing of the Business Combination Agreement, the Company will be required to reimburse GNI for such costs. If the Business Combination Agreement is terminated, the Company's repayment obligation varies depending on the clinical development of the F351 Assets. During the three and nine months ended September 30, 2023, the costs incurred for the development of the F351 Assets under the Cost Sharing and Agency Agreement were approximately $ 0.4 million and $ 0.7 million, respectively. As of September 30, 2023, GNI paid $ 0.3 million of the reimbursable development costs related to the F351 Assets, and the Company had a future repayment obligation of up to $ 0.3 million to this related party which was included in other accrued liabilities on the balance sheet. As part of the Business Combination Agreement, GNI agreed to share certain ongoing operating expenses of the Company that are incurred from December 26, 2022 until the Business Combination Agreement closes. All expenses required to be reimbursed as part of this agreement will be paid by GNI no later than three business days prior to the close of the Business Combination Agreement. All costs subject to reimbursement under the Business Combination Agreement must be approved by GNI. As of September 30, 2023, GNI had approved reimbursable operating costs incurred by Catalyst through June 30, 2023 in the amount of $ 1.2 million which the Company recognized as GNI cost-sharing reimbursement in the condensed consolidated statements of operations and comprehensive income (loss). As of September 30, 2023, the Company had amounts receivable from this related party of $ 1.2 million, which was included in other receivables from GNI on the condensed consolidated balance sheet. The Company has not recognized a receivable for operating costs incurred during the quarter ended September 30, 2023, since such reimbursement of costs remain subject to approval by GNI. Once GNI approves these costs, the Company will record the reimbursement in its condensed consolidated financial statements.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events On October 20, 2023, BC received approval from the CSRC with respect to the business combination pursuant to the Business Combination Agreement. Catalyst and GNI anticipate the business combination will be completed by the Outside Date (as defined in the Business Combination Agreement).

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
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 condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated 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 consolidated financial information. These condensed consolidated results of operations and cash flows for any interim period are not necessarily indicative of the results to be expected for the year ending December 31, 2023, 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, 2022 (the “Annual Report”).
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance for doubtful accounts, long-term receivable, CVR derivative liabilities, 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 June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments . 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 is effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, using a modified retrospective approach. The Company adopted ASU 2016-13 and related updates as of January 1, 2023 and the adoption did not have a material impact on its condensed consolidated financial statements.
Long-Term Receivable	Long-Term Receivable The Company determined that the hold-back from the GCBP asset sale in February 2023 qualified as a long-term receivable. The receivable is considered a loan held for investment since the Company has the intent and ability to hold to maturity. Catalyst has elected to account for the receivable under the fair value option method of accounting and any changes in fair value are recorded in interest and other income, net on the condensed consolidated statement of operations and comprehensive income (loss). Refer to Note 4, Fair Value Measurements and Note 11, Restructuring , for additional information regarding the long-term receivable and GCBP asset sale.
Net Income (Loss) per Share Attributable to Common Stockholders	Net Income (Loss) per Share Attributable to Common Stockholders The Company calculates basic and diluted net income (loss) per share attributable to common stockholders in conformity with the two-class method required for participating securities. The Catalyst Convertible Preferred Stock contractually entitles the holders of such shares to participate in dividends, but such participation is contingent upon the completion of the transactions under the Business Combination Agreement with GNI. As a result, the Catalyst Convertible Preferred Stock is excluded from the basic EPS calculation, as these shares are not participating securities until the Business Combination Agreement with GNI closes. During periods of loss, the Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. Basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Participating securities are excluded from the basic weighted average common shares outstanding. Diluted net income (loss) per share attributable to common stockholders is based on the weighted average number of common shares outstanding during the period, including potential dilutive common shares. For purposes of this calculation, outstanding stock options and warrants are considered potential dilutive common shares. The calculation of diluted EPS also considers the effect of the Catalyst Convertible Preferred Stock since conversion is no longer contingent after the stockholders approved the Conversion Proposal on August 29, 2023.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
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 September 30, 2023 and December 31, 2022 ( in thousands ): September 30, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 2,228 $ — $ — $ 2,228 Long-term receivable from GCBP — — 4,664 4,664 Total financial assets $ 2,228 $ — $ 4,664 $ 6,892 Financial liabilities: CVR derivative liability, noncurrent $ — $ — $ 4,664 $ 4,664 Total financial liabilities $ — $ — $ 4,664 $ 4,664 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds (1) $ 21,666 $ — $ — $ 21,666 Total financial assets $ 21,666 $ — $ — $ 21,666 Financial liabilities: CVR derivative liability $ — $ — $ 5,000 $ 5,000 Total financial liabilities $ — $ — $ 5,000 $ 5,000 (1) Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets.
Changes in Estimated Fair Value of Level 3 Financial Assets and Liabilities	The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial assets and liabilities ( in thousands ): Long-term receivable CVR derivative from GCBP liability, noncurrent Balance at December 31, 2022 $ — $ — Additions in the period 4,530 4,530 Changes in fair value 134 134 Balance at September 30, 2023 $ 4,664 $ 4,664

Lease (Tables)

Lease (Tables)	9 Months Ended
	Sep. 30, 2023
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: September 30, 2023 December 31, 2022 Weighted-average remaining lease term n/a 0.3 years Weighted-average discount rate n/a 4.3 %
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information related to operating leases was as follows (in thousands) : Nine Months Ended September 30, 2023 2022 Cash paid for amounts included in the measurement of lease liabilities $ 39 $ 1,422

Stock Based Compensation (Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [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 Weighted- Weighted- Outstanding — December 31, 2022 8,678,767 $ 1.42 7.47 Options granted (1) 14,008,093 $ 0.86 Options exercised ( 215,067 ) $ 0.10 Options forfeited and cancelled (1) ( 14,210,119 ) $ 0.91 Options expired ( 14,729 ) $ 34.33 Outstanding — September 30, 2023 8,246,945 $ 1.32 5.43 Exercisable — September 30, 2023 7,609,393 $ 1.37 (1) Includes options that were cancelled and re-granted as part of the option modification from the special cash dividend, as further discussed above.
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 September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Employee Stock Options: Risk-free interest rate n/a 3.02 % n/a 2.25 % Expected term (in years) n/a 6.1 n/a 6.0 Dividend yield n/a — n/a — Volatility n/a 91.61 % n/a 91.63 % Weighted-average fair value of stock options granted n/a $ 1.34 n/a $ 0.58
Summary of Stock-Based Compensation Expense Recognized	Total stock-based compensation expense recognized was as follows ( in thousands ): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Research and development $ — $ 78 $ 67 $ 289 General and administrative (1) 98 146 330 796 Total stock-based compensation expense $ 98 $ 224 $ 397 $ 1,085 (1) No shares of common stock were issued to Board members for the three and nine months ended September 30, 2023.

Net Income (Loss) per Share A_2

Net Income (Loss) per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2023
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: Nine Months Ended September 30, 2023 2022 Catalyst Convertible Preferred Stock (1) 123,400,000 — Options to purchase common stock 8,246,945 7,034,805 Total 131,646,945 7,034,805 (1) Shown as common stock equivalents
Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders	The following is a reconciliation of the numerator (net income or loss) and denominator (number of shares) used in the calculation of basic and diluted net income (loss) per share attributable to common stockholders (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Numerator Net income (loss) $ ( 1,576 ) $ ( 4,884 ) $ ( 3,788 ) $ 32,212 Denominator Weighted-average number of shares used in 37,976,764 31,484,542 37,845,900 31,472,666 Effect of dilutive stock options — — — 133,168 Weighted-average number of shares used in 37,976,764 31,484,542 37,845,900 31,605,834 Net income (loss) per share available for common $ ( 0.04 ) $ ( 0.16 ) $ ( 0.10 ) $ 1.02 Net income (loss) per share available for common $ ( 0.04 ) $ ( 0.16 ) $ ( 0.10 ) $ 1.02

Nature of Operations and Liqu_2

Nature of Operations and Liquidity - Additional Information (Detail) $ / shares in Units, $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

Aug. 29, 2023 shares

Aug. 21, 2023 USD ($) $ / shares

Jun. 05, 2023 USD ($) $ / shares

Mar. 08, 2023 USD ($) $ / shares

Jan. 12, 2023 USD ($) $ / shares

Dec. 26, 2022 USD ($) shares

Jun. 30, 2023 USD ($)

Sep. 30, 2023 USD ($) shares

Jun. 30, 2023 USD ($)

Mar. 31, 2023 USD ($) $ / shares

Sep. 30, 2022 USD ($) $ / shares

Jun. 30, 2022 USD ($)

Mar. 31, 2022 USD ($)

Sep. 30, 2023 USD ($) Segment $ / shares shares

Sep. 30, 2022 USD ($) $ / shares

Dec. 31, 2022 USD ($) shares

Organization and Nature of Operations [Line Items]

Number of operating segment | Segment

1

Dividends Payable, date declared

Jan. 12, 2023

Dividends paid | $ / shares

$ 0.24

$ 1.43

$ 0.24

$ 1.43

Amount of dividend payment

$ 7,600

Net income (loss)

$ (1,576)

$ (2,472)

$ 260

$ (4,884)

$ 51,632

$ (14,536)

$ (3,788)

$ 32,212

Accumulated deficit

414,724

414,724

$ 410,936

Cash and cash equivalents

$ 2,228

$ 2,228

$ 21,666

F351 Agreement

Organization and Nature of Operations [Line Items]

Assets acquisition, paid

$ 35,000

Purchase agreement amendment date

Mar. 29, 2023

Business Combination Agreement

Organization and Nature of Operations [Line Items]

Purchase agreement amendment date

Aug. 30, 2023

Mar. 29, 2023

Contingent Value Rights Agreement

Organization and Nature of Operations [Line Items]

Purchase agreement amendment date

Mar. 29, 2023

Dividends paid | $ / shares

$ 0.05

$ 0.11

$ 0.01

$ 0.01

Amount of dividend payment

$ 1,500

$ 3,500

$ 200

$ 3,500

Catalyst Convertible Preferred Stock

Organization and Nature of Operations [Line Items]

Preferred stock shares issued | shares

12,340

12,340

0

Catalyst Convertible Preferred Stock | F351 Agreement

Organization and Nature of Operations [Line Items]

Preferred stock shares issued | shares

12,340

Preferred stock, shares issued upon conversion of common stock | shares

10,000

10,000

Common Stock | F351 Agreement

Organization and Nature of Operations [Line Items]

Assets acquisition, shares issued | shares

6,266,521

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - ASU 2016-13	Sep. 30, 2023
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2023
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true

F351 Asset Acquisition - Additi

F351 Asset Acquisition - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Dec. 26, 2022	Dec. 31, 2022	Sep. 30, 2023
Convertible Preferred Stock
Asset Acquisition [Line Items]
Preferred stock shares issued		0	12,340
F351 Agreement | Convertible Preferred Stock
Asset Acquisition [Line Items]
Preferred stock shares issued	12,340
F351 Agreement | In-process Research and Development ("IPR&D")
Asset Acquisition [Line Items]
Acquisition cost		$ 35.4
Common Stock | F351 Agreement
Asset Acquisition [Line Items]
Assets acquisition, shares issued	6,266,521

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands		Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		$ 6,892	$ 21,666
Liabilities, fair value		4,664	5,000
Long-term receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		4,664
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	[1]	2,228	21,666
CVR Derivative Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value			5,000
CVR Derivative Liability non current
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value		4,664
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		2,228	21,666
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]	2,228	21,666
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		4,664
Liabilities, fair value		4,664	5,000
Fair Value, Inputs, Level 3 | Long-term receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value		4,664
Fair Value, Inputs, Level 3 | CVR Derivative Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value			$ 5,000
Fair Value, Inputs, Level 3 | CVR Derivative Liability non current
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value		$ 4,664
[1] Included in cash and cash equivalents on the accompanying condensed consolidated balance sheets.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Contingent Value Rights Agreement	9 Months Ended
	Sep. 30, 2023 USD ($)	Mar. 31, 2025 USD ($)	May 31, 2023 USD ($)	Dec. 26, 2022 USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Initial derivative liability				$ 5,000,000
Change in the estimated fair value	$ 0
Vertex Asset Purchase Agreement
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amount to be received under agreement			$ 5,000,000
GCBP Asset Purchase Agreement | CVR Derivative Liability non current | Estimated Discount Rate
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative liability measurement input	0.0505
GCBP Asset Purchase Agreement | Long-term receivable | Estimated Discount Rate
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative asset measurement input	0.0505
GCBP Asset Purchase Agreement | Forecast
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amount to be received under agreement		$ 5,000,000

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Estimated Fair Value of Level 3 Financial Assets and Liabilities (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Long-term receivable
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Additions in the period	$ 4,530
Changes in fair value	134
Balance at September 30, 2023	4,664
CVR Derivative Liability non current
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Additions in the period	4,530
Changes in fair value	134
Balance at September 30, 2023	$ 4,664

Lease - Additional Information

Lease - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessee Lease Description [Line Items]
Lease expiration date				Apr. 30, 2023
Operating lease expense		$ 0	$ 400,000	$ 100,000	$ 1,500,000
Sublease Arrangement
Lessee Lease Description [Line Items]
Lease commencement month and year	2022-04
Lease expiration month and year	2023-04
Lease payments receivable	$ 200,000
Sublease Income		$ 0	$ 38,000	$ 100,000	$ 100,000

Lease - Summary of Present Valu

Lease - Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments (Detail)	Dec. 31, 2022
Lessee Disclosure [Abstract]
Weighted-average remaining lease term	3 months 18 days
Weighted-average discount rate	4.30%

Lease - Schedule of Supplementa

Lease - Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 39	$ 1,422

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
	Jan. 12, 2023	Jun. 09, 2021	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock available for future grant					25,521,867
Options vested			0
Aggregate amount of special dividend payment	$ 7.6
Dividends paid	$ 0.24			$ 1.43	$ 0.24	$ 1.43
Dividends Payable, date declared	Jan. 12, 2023
Stock options granted during quarter					0
2018 Omnibus Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
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			31,456,403
2018 Omnibus Incentive Plan | Performance Based Stock Option Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of option grants to purchase common stock shares					400,000
2018 Omnibus Incentive Plan | Accounting Standards Update 2021-04 | Performance Based Stock Option Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of option grants to purchase common stock shares					2,457,917

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Option Activity Under Company's Equity Incentive Plans (Detail) - $ / shares		9 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2022
Number of Shares Underlying Outstanding Options
Number of Shares Underlying Outstanding Options, Beginning Balance		8,678,767
Number of Shares Underlying Outstanding Options, Options granted	[1]	14,008,093
Number of Shares Underlying Outstanding Options, Options exercised		(215,067)
Number of Shares Underlying Outstanding Options, Options forfeited and cancelled	[1]	(14,210,119)
Number of Shares Underlying Outstanding Options, Options expired		(14,729)
Number of Shares Underlying Outstanding Options, Ending Balance		8,246,945	8,678,767
Number of Shares Underlying Outstanding Options, Exercisable- June 30, 2023		7,609,393
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning Balance		$ 1.42
Weighted- Average Exercise Price, Options granted	[1]	0.86
Weighted- Average Exercise Price, Options Exercised		0.1
Weighted- Average Exercise Price, Options forfeited and cancelled	[1]	0.91
Weighted- Average Exercise Price, Options expired		34.33
Weighted- Average Exercise Price, Ending Balance		1.32	$ 1.42
Weighted- Average Exercise Price, Exercisable - June 30, 2023		$ 1.37
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding Balance		5 years 5 months 4 days	7 years 5 months 19 days
[1] Includes options that were cancelled and re-granted as part of the option modification from the special cash dividend, as further discussed above.

Stock Based Compensation - Fair

Stock Based Compensation - Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail) - Employee Stock Option - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Risk-free interest rate	3.02%	2.25%
Expected term (in years)	6 years 1 month 6 days	6 years
Dividend yield	0%	0%
Volatility	91.61%	91.63%
Weighted-average fair value of stock options granted	$ 1.34	$ 0.58

Stock Based Compensation - Su_2

Stock Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation		$ 98	$ 224	$ 397	$ 1,085
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation			78	67	289
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	[1]	$ 98	$ 146	$ 330	$ 796
[1] No shares of common stock were issued to Board members for the three and nine months ended September 30, 2023.

Stock Based Compensation - Su_3

Stock Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2023 shares
Share-Based Payment Arrangement [Abstract]
Number of shares of common stock issued to certain board members in lieu of cash compensation	0

Net Income (Loss) per Share A_3

Net Income (Loss) per Share Attributable to Common Stockholders - Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti dilutive securities		131,646,945	7,034,805
Catalyst Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti dilutive securities	[1]	123,400,000
Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti dilutive securities		8,246,945	7,034,805
[1] Shown as common stock equivalents

Net Income (Loss) per Share A_4

Net Income (Loss) per Share Attributable to Common Stockholders - Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net income (loss)	$ (1,576)	$ (4,884)	$ (3,788)	$ 32,212
Weighted-average number of shares used in computing net income (loss) per share available to common stockholders, basic	37,976,764	31,484,542	37,845,900	31,472,666
Effect of dilutive stock options				133,168
Weighted-average number of shares used in computing net income (loss) per share available to common stockholders, diluted	37,976,764	31,484,542	37,845,900	31,605,834
Net income (loss) per share available for common stockholders, basic	$ (0.04)	$ (0.16)	$ (0.1)	$ 1.02
Net income (loss) per share available for common stockholders, dilutive	$ (0.04)	$ (0.16)	$ (0.1)	$ 1.02

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)				1 Months Ended		9 Months Ended
	Aug. 21, 2023 USD ($)	Jun. 05, 2023 USD ($)	Apr. 18, 2023 USD ($) Agreement	Mar. 31, 2023 USD ($)	Feb. 28, 2023 USD ($)	Sep. 30, 2023 USD ($) shares	Dec. 31, 2022 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Long-term CVR derivative liability						$ 4,664,000
CVR derivative liability							$ 5,000,000
Number of separate agreements | Agreement			2
Non GMP Manufacturing Services
Commitments And Contingencies Disclosure [Line Items]
Cost of services as per agreement			$ 300,000
Clinical Supply Batch GMP Manufacturing
Commitments And Contingencies Disclosure [Line Items]
Cost of services as per agreement			$ 200,000
Contingent Value Rights Agreement
Commitments And Contingencies Disclosure [Line Items]
Percentage of excess cash on dispositions net						100%
Percentage of excess cash on dispositions net						$ 1,000,000
Percentage of excess preapproved costs						100%
Short-term CVR derivative liability							$ 5,000,000
Long-term CVR derivative liability					$ 4,500,000
CVR derivative liability						$ 0
Distribution to CVR holders from asset sale proceeds	$ 1,500,000	$ 3,500,000		$ 200,000	$ 200,000
Related Party | Non GMP Manufacturing Services | Other Accrued Liabilities
Commitments And Contingencies Disclosure [Line Items]
Future repayment obligation to related party						300,000
GNI | Related Party | Non GMP Manufacturing Services
Commitments And Contingencies Disclosure [Line Items]
Reimbursable development costs						$ 300,000
Vertex Asset Purchase Agreement | Contingent Value Rights Agreement
Commitments And Contingencies Disclosure [Line Items]
Percentage of amount received on agreement, net of expenses						100%
F351 | GNI | Business Combination Agreement
Commitments And Contingencies Disclosure [Line Items]
Termination fee required to pay upon termination of agreement						$ 2,000,000
F351 | GNI | Maximum | Business Combination Agreement
Commitments And Contingencies Disclosure [Line Items]
Common stock, shares issued | shares						1,110,776,224
Reimbursement for out-of-pocket fees and expenses						$ 2,000,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Tax [Line Items]
Income tax expense (benefits)	$ 0	$ 0	$ 16,000	$ 0
Research and Development Tax Credits
Income Tax [Line Items]
Income tax expense (benefits)			0
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	193,700,000		193,700,000
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	$ 3,700,000		$ 3,700,000
Net operating loss carryforwards expiration year			2034

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) - Additional Information (Detail) - $ / shares		9 Months Ended
	Aug. 28, 2023	Sep. 30, 2023	Aug. 29, 2023	Jun. 20, 2023	Dec. 31, 2022
Stockholders Equity Disclosure [Line Items]
Preferred stock shares authorized		5,000,000
Preferred stock par value per share		$ 0.001
Common stock, shares authorized	100,000,000	100,000,000	400,000,000		100,000,000
Redeemable Convertible Preferred Stock
Stockholders Equity Disclosure [Line Items]
Preferred stock shares authorized		123,418
Series Y Redeemable Preferred Stock
Stockholders Equity Disclosure [Line Items]
Preferred stock shares authorized		161,160
Preferred stock, voting rights		250,000 votes per share
Number of shares of the stockholders represented in person or by proxy			25,256
Redeemed stock	135,904
Series Y Redeemable Preferred Stock | One One-Thousandth Share Dividend Declared
Stockholders Equity Disclosure [Line Items]
Dividend declared, per share				$ 0.001

Restructuring - Additional Info

Restructuring - Additional Information (Detail) $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

Aug. 21, 2023 USD ($)

Jun. 05, 2023 USD ($)

Mar. 08, 2023 USD ($)

Jan. 12, 2023 USD ($)

Jun. 30, 2023 USD ($)

Mar. 31, 2023 USD ($)

Feb. 28, 2023 USD ($)

May 31, 2022 USD ($)

Mar. 31, 2022 Employee

Nov. 30, 2021

Jun. 30, 2022 USD ($)

Mar. 31, 2022 USD ($)

Sep. 30, 2023 USD ($)

Sep. 30, 2022 USD ($)

Restructuring Cost And Reserve [Line Items]

Percent of employees terminated

35%

Number of Employees terminated | Employee

22

Remaining number of full time employees | Employee

5

Proceeds from Sale of Intangible Assets

$ 1,000

Gain (loss) on disposal

4,736

$ 57,245

Amount of dividend payment

$ 7,600

Contingent Value Rights Agreement

Restructuring Cost And Reserve [Line Items]

Distribution to CVR holders from asset sale proceeds

$ 1,500

$ 3,500

$ 200

$ 200

Amount of dividend payment

$ 1,500

$ 3,500

$ 200

$ 3,500

Vertex Pharmaceuticals Incorporated

Restructuring Cost And Reserve [Line Items]

Proceeds from Sale of Intangible Assets

$ 60,000

Upfront payment received

55,000

Post closing indemnification obligation

5,000

Gain (loss) on disposal

$ 57,400

Transaction costs

$ 2,600

GCBP Asset Purchase Agreement

Restructuring Cost And Reserve [Line Items]

Proceeds from Sale of Intangible Assets

6,000

Upfront payment received

1,000

Post closing indemnification obligation

5,000

Gain (loss) on disposal

$ 4,700

Transaction costs

800

Dren Bio, Inc. and Copia Scientific, LLC

Restructuring Cost And Reserve [Line Items]

Total consideration for sales agreements

$ 400

Gain (loss) on disposal

$ (200)

Operating Expense

Restructuring Cost And Reserve [Line Items]

Restructuring costs

$ 1,000

Related Parties - Additional In

Related Parties - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 26, 2022	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
GNI cost-sharing reimbursement		$ 1,200	$ 1,200
GNI
Related Party Transaction [Line Items]
Percentage of convertible preferred stock owned	100%
Percentage of common stock outstanding			16.50%	16.60%
Percentage of outstanding shares of capital stock			80.30%	80.50%
Minimum percentage of director to stockholder of the company			5%
Related Party
Related Party Transaction [Line Items]
Amounts receivable from related party		1,200	$ 1,200
Business Combination Agreement
Related Party Transaction [Line Items]
GNI cost-sharing reimbursement			1,200
Business Combination Agreement | Related Party | Accounts And Other Receivables
Related Party Transaction [Line Items]
Amounts receivable from related party		1,200	1,200
Non GMP Manufacturing Services
Related Party Transaction [Line Items]
Cost of services as per agreement		400	700
Non GMP Manufacturing Services | Related Party | Other Accrued Liablities | Maximum
Related Party Transaction [Line Items]
Future repayment obligation to related party		$ 300	300
Non GMP Manufacturing Services | Related Party | GNI
Related Party Transaction [Line Items]
Reimbursable development costs			$ 300

Condensed Consolidated Financia

Condensed Consolidated Financial Statements Detail - Schedule of Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Condensed Financial Information Disclosure [Abstract]
Total other accrued liabilities	$ 917	$ 1,452