SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Koppel Adam (Last) (First) (Middle) C/O BAIN CAPITAL LIFE SCIENCES INVESTORS LLC, 200 CLARENDON STREET (Street) BOSTON MA 02116 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Solid Biosciences Inc. [ SLDB ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 01/30/2018
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	01/25/2018		M(3)		1,689,444(3)	A	(3)	1,689,444(3)	I	See Footnotes(1)(2)
Common Stock	01/30/2018		P		300,000(4)	A	$16	1,989,444(3)	I	See Footnotes(1)(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
LLC Units	(3)	10/26/2017		A		1,223,240(3)		(3)	(3)	Common Stock	1,037,919(3)	(3)	1,991,097(3)	I	See footnotes(1)(2)
LLC Units	(3)	01/25/2018		M			1,991,097(3)	(3)	(3)	Common Stock	1,689,444(3)	(3)	0(3)	I	See footnotes(1)(2)

Explanation of Responses:

1. Represents shares held directly by BCLS SB Investco, LP ("BCLS").

2. The governance, investment strategy and decision-making process with respect to investments held by BCLS is directed by Bain Capital Life Sciences Investors, LLC, whose managers are Jeffrey Schwartz and Adam Koppel. By virtue of the relationships described in these footnotes, Dr. Koppel may be deemed to share voting and dispositive power with respect to all of the shares of Common Stock held by BCLS. Dr. Koppel disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

3. In connection with the Issuer's initial public offering, immediately prior to the effectiveness of the Issuer's Registration Statement on Form S-1 relating thereto, the Issuer, which was previously organized as a limited liability company, converted to a corporation (the "Corporate Conversion"). Prior to the Corporate Conversion, BCLS held 1,991,097 LLC Units of the Issuer, including 112,770 Series C Common Units acquired for a total purchase price of $1,249,999.07 and 1,110,470 Series 2 Preferred Units acquired for a total purchase price of $ 12,500,560.97, in each case on October 26, 2017. In connection with the Corporate Conversion, all outstanding units of the Issuer were converted into shares of Common Stock on a one-for-0.8485 basis in an exempt transaction pursuant to Rule 16b-7. As a result, following the Corporate Conversion, BCLS held 1,689,444 shares of Common Stock.

4. Represents shares purchased in the Issuer's initial public offering.

Remarks:

	/s/ Adam Koppel	02/01/2018
	** Signature of Reporting Person	Date
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