SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Polaris Management Co. VII, L.L.C.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 3,023,161.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 3,023,161.00

11

Aggregate amount beneficially owned by each reporting person

3,023,161.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.8 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

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").

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Polaris Partners VII, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,825,500.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,825,500.00

11

Aggregate amount beneficially owned by each reporting person

2,825,500.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.5 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Polaris Entrepreneurs' Fund VII, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 197,661.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 197,661.00

11

Aggregate amount beneficially owned by each reporting person

197,661.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.3 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Polaris Partners GP X, L.L.C.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 909,090.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 909,090.00

11

Aggregate amount beneficially owned by each reporting person

909,090.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.4 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Polaris Partners X, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 909,090.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 909,090.00

11

Aggregate amount beneficially owned by each reporting person

909,090.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.4 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Amir Nashat

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 3,932,251.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 3,932,251.00

11

Aggregate amount beneficially owned by each reporting person

3,932,251.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

6.3 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Brian Chee

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 909,090.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 909,090.00

11

Aggregate amount beneficially owned by each reporting person

909,090.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.4 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

CUSIP No.

1

Name of reporting person

Amy Schulman

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 909,090.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 909,090.00

11

Aggregate amount beneficially owned by each reporting person

909,090.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.4 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

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.

SCHEDULE 13D

Item 1.

Security and Issuer

(a)

Title of Class of Securities:

Common Stock, par value $0.0001 per share

(b)

Name of Issuer:

Camp4 Therapeutics Corporation

(c)

Address of Issuer's Principal Executive Offices:

100 Talcott Avenue, Suite 201, Watertown, MASSACHUSETTS , 02472.

Item 1 Comment:

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.

Item 5.

Interest in Securities of the Issuer

(a)

See Items 7-11 and 13 of the cover pages of this Statement for each Reporting Person and the corresponding comments.

(b)

See Items 7-11 and 13 of the cover pages of this Statement for each Reporting Person and the corresponding comments.

(e)

Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Polaris Management Co. VII, L.L.C.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Attorney-in-Fact
Date:	08/19/2026

Polaris Partners VII, L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Attorney-in-Fact for Polaris Management Co. VII, L.L.C. the general partner of Polaris Partners VII, L.P.
Date:	08/19/2026

Polaris Entrepreneurs' Fund VII, L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Attorney-in-Fact for Polaris Management Co. VII, L.L.C. the general partner of Polaris Entrepreneurs' Fund VII, L.P.
Date:	08/19/2026

Polaris Partners GP X, L.L.C.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, General Counsel
Date:	08/19/2026

Polaris Partners X, L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, General Counsel of Polaris Partners GP X, L.L.C. the general partner of Polaris Partners X, L.P.
Date:	08/19/2026

Amir Nashat

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Authorized Signatory
Date:	08/19/2026

Brian Chee

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Authorized Signatory
Date:	08/19/2026

Amy Schulman

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett, Authorized Signatory
Date:	08/19/2026

Comments accompanying signature:

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.