Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

  NAMES OF REPORTING PERSONS

  Third Rock Ventures III, L.P.

  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

  (a)  ☐        (b)  ☒

  SEC USE ONLY

  CITIZENSHIP OR PLACE OF ORGANIZATION

  Delaware

NUMBER OF

SHARES

 BENEFICIALLY 

OWNED BY

EACH

REPORTING

PERSON

WITH

  SOLE VOTING POWER

  0

  SHARED VOTING POWER

  0

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  0

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  0

  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

  0% (1)

  TYPE OF REPORTING PERSON

  PN

The percent of class was calculated based on 47,147,781 shares of common stock issued and outstanding as of September 30, 2022, as disclosed in the Issuer’s 10-Q filed with the Securities and Exchange Commission on October 6, 2022.

  NAMES OF REPORTING PERSONS

  Third Rock Ventures GP III, L.P.

  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

  (a)  ☐        (b)  ☒

  SEC USE ONLY

  CITIZENSHIP OR PLACE OF ORGANIZATION

  Delaware

NUMBER OF

SHARES

 BENEFICIALLY 

OWNED BY

EACH

REPORTING

PERSON

WITH

  SOLE VOTING POWER

  0

  SHARED VOTING POWER

  0

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  0

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  0

  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

  0% (1)

  TYPE OF REPORTING PERSON

  PN

  NAMES OF REPORTING PERSONS

  TRV GP III, LLC

  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

  (a)  ☐        (b)  ☒

  SEC USE ONLY

  CITIZENSHIP OR PLACE OF ORGANIZATION

  Delaware

NUMBER OF

SHARES

 BENEFICIALLY 

OWNED BY

EACH

REPORTING

PERSON

WITH

  SOLE VOTING POWER

  0

  SHARED VOTING POWER

  0

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  0

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  0

  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

  0% (1)

  TYPE OF REPORTING PERSON

  OO

  NAMES OF REPORTING PERSONS

  Robert I. Tepper

  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

  (a)  ☐        (b)  ☒

  SEC USE ONLY

  CITIZENSHIP OR PLACE OF ORGANIZATION

  United States

NUMBER OF

SHARES

 BENEFICIALLY 

OWNED BY

EACH

REPORTING

PERSON

WITH

  SOLE VOTING POWER

  184,544

  SHARED VOTING POWER

  0

  SOLE DISPOSITIVE POWER

  184,544

  SHARED DISPOSITIVE POWER

  0

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  184,544

  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

  0.4%

  TYPE OF REPORTING PERSON

  IN

Issuer

Name of Issuer:

Address of Issuer’s Principal Executive Offices:

Filing Person

Third Rock Ventures III, L.P. (“TRV III”);

Third Rock Ventures GP III, L.P. (“TRV GP III”), which is the sole general partner of TRV III;

TRV GP III, LLC (“TRV GP III LLC”), which is the sole general partner of TRV GP III; and

Robert I. Tepper (“Tepper,” and collectively with TRV III, TRV GP III and TRV GP III, the “Reporting Persons”), the managing member of TRV GP III LLC.

Title of Class of Securities:

CUSIP Number:

If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under Section 15 of the Act;

(b)

Bank as defined in Section 3(a)(6) of the Act;

(c)

Insurance company as defined in Section 3(a)(19) of the Act;

(d)

Investment company registered under Section 8 of the Investment Company Act of 1940;

(e)

An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

(j)

A non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J);

(k)

Ownership.

and (b) Amount beneficially owned:

TRV III directly owns 0 shares of Common Stock (the “Shares”), which represents approximately 0% of the outstanding shares of Common Stock.

TRV GP III is the general partner of TRV III and may be deemed to beneficially own the Shares.

TRV GP III LLC is the general partner of TRV GP III and may be deemed to beneficially own the Shares.

As a managing member of TRV GP III LLC, Tepper may be deemed to beneficially own the Shares. Additionally, Tepper directly owns 44,878 shares of Common Stock and owns 139,666 shares of Common Stock through a trust.

Number of shares as to which such person has:

TRV III

TRV GP III

TRV GP III LLC

Tepper

Sole power to vote or direct the vote

Shared power to vote or to direct the vote

Sole power to dispose or to direct the disposition of

Shared power to dispose or to direct the disposition of

Ownership of Five Percent or Less of a Class.

Ownership of More than Five Percent on Behalf of Another Person.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Identification and Classification of Members of the Group.

Notice of Dissolution of Group.

Certification.

THIRD ROCK VENTURES III, L.P.

By: THIRD ROCK VENTURES GP III, L.P.,

General Partner

By: TRV GP III, LLC,

General Partner

THIRD ROCK VENTURES GP III, L.P.

General Partner

TRV GP III, LLC

ROBERT I. TEPPER

/s/ Kevin Gillis, As attorney-in-fact

Robert I. Tepper