Third Rock Ventures III SC 13G Decibel Therapeutics / Third Rock Ventures III ownership change

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No.     )*

Decibel Therapeutics, Inc.

(Name of Issuer)

COMMON STOCK, $0.001 PAR VALUE PER SHARE

(Title of Class of Securities)

24343R106

(CUSIP Number)

December 31, 2021

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ 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.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 24343R106 SCHEDULE 13G Page 2 of 11 Pages

1.	NAMES OF REPORTING PERSONS   Third Rock Ventures III, L.P.
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   PN

(1) The percent of class was calculated based on 24,923,363 shares of common stock issued and outstanding as of November 1, 2021, as disclosed in the Issuer’s 10-Q filed with the Securities and Exchange Commission on November 10, 2021.

CUSIP No. 24343R106 SCHEDULE 13G Page 3 of 11 Pages

1.	NAMES OF REPORTING PERSONS   Third Rock Ventures GP III, L.P.
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   PN

CUSIP No. 24343R106 SCHEDULE 13G Page 4 of 11 Pages

1.	NAMES OF REPORTING PERSONS   TRV GP III, LLC
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   OO

CUSIP No. 24343R106 SCHEDULE 13G Page 5 of 11 Pages

1.	NAMES OF REPORTING PERSONS   Mark Levin
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   United States

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   IN

CUSIP No. 24343R106 SCHEDULE 13G Page 6 of 11 Pages

1.	NAMES OF REPORTING PERSONS   Kevin P. Starr
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   United States

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   IN

CUSIP No. 24343R106 SCHEDULE 13G Page 7 of 11 Pages

1.	NAMES OF REPORTING PERSONS   Robert I. Tepper
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP   (a)  ☐        (b)  ☒
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION   United States

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5.	SOLE VOTING POWER   0
	6.	SHARED VOTING POWER   3,139,685
	7.	SOLE DISPOSITIVE POWER   0
	8.	SHARED DISPOSITIVE POWER   3,139,685

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,139,685
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES   ☐
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9   12.6% (1)
12.	TYPE OF REPORTING PERSON   IN

CUSIP No. 24343R106 SCHEDULE 13G Page 8 of 11 Pages

Item 1.		Issuer
	(a)	Name of Issuer:
		Decibel Therapeutics, Inc. (the “Issuer”)
	(b)	Address of Issuer’s Principal Executive Offices:
		1325 Boylston Street, Suite 500 Boston, MA 02215
Item 2.		Filing Person
	(a) – (c)	Name of Persons Filing; Address; Citizenship:
		(i) Third Rock Ventures III, L.P. (“TRV III”); (ii)  Third Rock Ventures GP III, L.P. (“TRV GP III”), which is the sole general partner of TRV III; (iii)  TRV GP III, LLC (“TRV GP III LLC”), which is the sole general partner of TRV GP III; (iv) Mark Levin (“Levin”), a managing member of TRV GP III LLC; (v)   Kevin P. Starr (“Starr”), a managing member of TRV GP III LLC; and (vi) Robert I. Tepper (“Tepper,” and collectively with TRV III, TRV GP III, TRV GP III, Levin and Starr, the “Reporting Persons”), a managing member of TRV GP III LLC. The address of the principal business office of each of the Reporting Persons is Third Rock Ventures, LLC, 29 Newbury Street, 3rd Floor, Boston, MA 02116. Each of TRV III and TRV GP III is a Delaware limited partnership. TRV GP III LLC is a Delaware limited liability company. Levin, Tepper and Starr are United States citizens.
	(d)	Title of Class of Securities:
		Common stock, $0.001 par value per share, (the “Common Stock”)
	(e)	CUSIP Number: 24343R106
Item 3.	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)	☐	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940;
	(j)	☐	A non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J);

CUSIP No. 24343R106 SCHEDULE 13G Page 9 of 11 Pages

	(k)	☐	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
		If filing as a non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J), please specify the type of institution:
Item 4.	Ownership.
	(a) and (b)	Amount beneficially owned:
		(i)	TRV III directly owns 3,139,685 shares of Common Stock (the “Shares”), which represents approximately 12.6% of the outstanding shares of Common Stock.
		(ii)	TRV GP III is the general partner of TRV III and may be deemed to beneficially own the Shares.
		(iii)	TRV GP III LLC is the general partner of TRV GP III and may be deemed to beneficially own the Shares.
		(iv)	As a managing member of TRV GP III LLC, Levin may be deemed to beneficially own the Shares.
		(v)	As a managing member of TRV GP III LLC, Tepper may be deemed to beneficially own the Shares.
		(vi)	As a managing member of TRV GP III LLC, Starr may be deemed to beneficially own the Shares.
	(c)	Number of shares as to which such person has:

	Number of Shares of Common Stock
Reporting Person	(i)		(ii)		(iii)		(iv)
TRV III		0		3,139,685		0		3,139,685
TRV GP III		0		3,139,685		0		3,139,685
TRV GP III LLC		0		3,139,685		0		3,139,685
Levin		0		3,139,685		0		3,139,685
Starr		0		3,139,685		0		3,139,685
Tepper		0		3,139,685		0		3,139,685

	(i) Sole power to vote or direct the vote (ii)  Shared power to vote or to direct the vote (iii)  Sole power to dispose or to direct the disposition of (iv) Shared power to dispose or to direct the disposition of
	The percent of class was calculated based on 24,923,363 shares of common stock issued and outstanding as of November 1, 2021, as disclosed in the Issuer’s 10-Q filed with the Securities and Exchange Commission on November 10, 2021.
Item 5.	Ownership of Five Percent or Less of a Class. Not applicable.
Item 6.	Ownership of More than Five Percent on Behalf of Another Person. Not applicable.

CUSIP No. 24343R106 SCHEDULE 13G Page 10 of 11 Pages

Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person. Not applicable.
Item 8.	Identification and Classification of Members of the Group. Not applicable.
Item 9.	Notice of Dissolution of Group. Not applicable.
Item 10.	Certification. Not applicable.

CUSIP No. 24343R106 SCHEDULE 13G Page 11 of 11 Pages

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.

Date: February 14, 2022

THIRD ROCK VENTURES III, L.P.
By: THIRD ROCK VENTURES GP III, L.P.,
General Partner
By: TRV GP III, LLC,
General Partner
By:	/s/ Kevin Gillis
Kevin Gillis
Chief Operating Officer
THIRD ROCK VENTURES GP III, L.P.
By: TRV GP III, LLC,
General Partner
By:	/s/ Kevin Gillis
Kevin Gillis
Chief Operating Officer
TRV GP III, LLC
By:	/s/ Kevin Gillis
Kevin Gillis
Chief Operating Officer
MARK LEVIN
/s/ Kevin Gillis, As attorney-in-fact
Mark Levin
KEVIN P. STARR
/s/ Kevin Gillis, As attorney-in-fact
Kevin P. Starr
ROBERT I. TEPPER
/s/ Kevin Gillis, As attorney-in-fact
Robert I. Tepper