X0202 SCHEDULE 13D/A 0001678203 XXXXXXXX LIVE 2 Common Stock, par value $0.0001 per share 08/13/2026 false 0001736730 13463J101 Camp4 Therapeutics Corporation

100 Talcott Avenue Suite 201 Watertown MA 02472

Lauren Crockett (781) 290-0770 Polaris Partners One Marina Park Drive, 8th Floor Boston MA 02210 0001678203 N Polaris Management Co. VII, L.L.C. b AF N DE 0 3023161 0 3023161 3023161 N 4.8 OO Consists of (i) 2,825,500 shares of Common Stock (as defined in Item 1 of the Original Schedule 13D (as defined below)) held of record by PP VII (as defined in Item 2(a) of the Original Schedule 13D) and (ii) 197,661 shares of Common Stock held of record by PEF VII (as defined in Item 2(a) of the Original Schedule 13D). PMC VII (as defined in Item 2(a) of the Original Schedule 13D) is the general partner of each of PP VII and PEF VII and may be deemed to have voting, investment and dispositive power with respect to these securities. The PMC VII Managing Members (as defined in Item 2(a) of the Original Schedule 13D), including Mr. Nashat (as defined in Item 2(a) of the Original Schedule 13D) who is a member of the Issuer's board of directors, are the managing members of PMC VII and may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as reported by the Issuer in its Quarterly Report on Form 10-Q for the quarter-ended June 30, 2026, filed with the Securities and Exchange Commission (the "Commission") on August 13, 2026 (the "Form 10-Q"). 0001611189 N Polaris Partners VII, L.P. b WC N DE 0 2825500 0 2825500 2825500 N 4.5 PN All shares of Common Stock are held of record by PP VII. PMC VII is the general partner of PP VII and may be deemed to have voting, investment and dispositive power with respect to these securities. The PMC VII Managing Members, including Mr. Nashat who is a member of the Issuer's board of directors, are the managing members of PMC VII and may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001615991 N Polaris Entrepreneurs' Fund VII, L.P. b WC N DE 0 197661 0 197661 197661 N 0.3 PN All shares of Common Stock are held of record by PEF VII. PMC VII is the general partner of PEF VII and may be deemed to have voting, investment and dispositive power with respect to these securities. The PMC VII Managing Members, including Mr. Nashat who is a member of the Issuer's board of directors, are the managing members of PMC VII and may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001910575 N Polaris Partners GP X, L.L.C. b AF N DE 0 909090 0 909090 909090 N 1.4 OO Consists of 909,090 shares of Common Stock held of record by PP X (as defined in Item 2(a) of the Original Schedule 13D). PPGP X (as defined in Item 2(a) of the Original Schedule 13D) is the general partner of PP X and may be deemed to have voting, investment and dispositive power with respect to these securities. Each of Ms. Schulman and Mr. Chee (both as defined in Item 2(a) of the Original Schedule 13D) are the managing members of PPGP X. Mr. Nashat, a member of the Issuer's board of directors, holds an interest in PPGP X. Each of the PPGP X Managing Members (as defined in Item 2(a) of the Original Schedule 13D) and Mr. Nashat may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001910577 N Polaris Partners X, L.P. b WC N DE 0 909090 0 909090 909090 N 1.4 PN All shares of Common Stock are held of record by PP X. PPGP X is the general partner of PP X. The PPGP X Managing Members are the managing members of PPGP X. Mr. Nashat, a member of the Issuer's board of directors, is an interest holder of PPGP X. Each of the PPGP X Managing Members and Mr. Nashat may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001575843 N Amir Nashat b AF N X1 0 3932251 0 3932251 3932251 N 6.3 IN Consists of (i) 2,825,500 shares of Common Stock held of record by PP VII, (ii) 197,661 shares of Common Stock held of record by PEF VII, and (iii) 909,090 shares of Common Stock held of record by PP X. PMC VII is the general partner of each of PP VII and PEF VII and may be deemed to have voting, investment and dispositive power with respect to these securities. The PMC VII Managing Members, including Mr. Nashat who is a member of the Issuer's board of directors, are the managing members of PMC VII and may be deemed to share voting, investment and dispositive power with respect to these securities. PPGP X is the general partner of PP X. The PPGP X Managing Members are the managing members of PPGP X. Mr. Nashat, a member of the Issuer's board of directors, is an interest holder of PPGP X. Each of the PPGP X Managing Members and Mr. Nashat may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001295675 N Brian Chee b AF N X1 0 909090 0 909090 909090 N 1.4 IN All shares of Common Stock are held of record by PP X. PPGP X is the general partner of PP X. The PPGP X Managing Members are the managing members of PPGP X. Mr. Nashat, a member of the Issuer's board of directors, is an interest holder of PPGP X. Each of the PPGP X Managing Members and Mr. Nashat may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. 0001438226 N Amy Schulman b AF N X1 0 909090 0 909090 909090 N 1.4 IN All shares of Common Stock are held of record by PP X. PPGP X is the general partner of PP X. The PPGP X Managing Members are the managing members of PPGP X. Mr. Nashat, a member of the Issuer's board of directors, is an interest holder of PPGP X. Each of the PPGP X Managing Members and Mr. Nashat may be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 13 is based on 62,753,200 shares of Common Stock outstanding as of August 12, 2026, as set forth in the Form 10-Q. Common Stock, par value $0.0001 per share Camp4 Therapeutics Corporation 100 Talcott Avenue Suite 201 Watertown MA 02472 This Amendment No. 2 (this "Amendment") amends and supplements the Schedule 13D originally filed by the Reporting Persons with the Commission on October 22, 2024 as amended by Amendment No. 1 filed with the Commission on September 11, 2025 (collectively, the "Original Schedule 13D"). Only those items that are hereby reported are amended; all other items reported in the Original Schdule 13D remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment have the meanings ascribed to them in the Original Schedule 13D. This Amendment is being filed to update the aggregate percentage of Common Stock owned by the Reporting Persons due to dilution caused by the Issuer's sales of additional shares of its Common Stock from time to time since the date of the filing of Amendment No. 1. Such transactions resulted in a decrease of over one percent (1%) in the aggregate percentage ownership reported by the Reporting Persons in Amendment No. 1. See Items 7-11 and 13 of the cover pages of this Statement for each Reporting Person and the corresponding comments. See Items 7-11 and 13 of the cover pages of this Statement for each Reporting Person and the corresponding comments. Not applicable. Polaris Management Co. VII, L.L.C. /s/ Lauren Crockett 08/19/2026 Polaris Partners VII, L.P. /s/ Lauren Crockett 08/19/2026 Polaris Entrepreneurs' Fund VII, L.P. /s/ Lauren Crockett 08/19/2026 Polaris Partners GP X, L.L.C. /s/ Lauren Crockett 08/19/2026 Polaris Partners X, L.P. /s/ Lauren Crockett 08/19/2026 Amir Nashat /s/ Lauren Crockett 08/19/2026 Brian Chee /s/ Lauren Crockett 08/19/2026 Amy Schulman /s/ Lauren Crockett 08/19/2026 This Amendment was executed with respect to each of Amir Nashat, Brian Chee, and Amy Schulman pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are already on file with the appropriate agencies.