SC 13D/A





Washington, DC 20549




(Rule 13d-101)

Information to be Included in Statements Filed Pursuant

to § 240.13d-1(a) and Amendments Thereto Filed

Pursuant to § 240.13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No. 4)



Solid Biosciences Inc.

(Name of Issuer)

Common Stock, $0.001

par value per share

(Title of Class of Securities)

83422E 105

(CUSIP Number)

Bain Capital Life Sciences Investors, LLC

200 Clarendon Street

Boston, MA 02116


(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

August 18, 2022

(Date of Event Which Requires Filing of This Statement)



If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ☐



Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7 for other parties to whom copies are to be sent.



The information required on 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, as amended (“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).





  Names of reporting persons


  BCLS SB Investco, LP


  Check the appropriate box if a member of a group

  (a)  ☐        (b)  ☐



  SEC use only



  Source of funds




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




  Citizenship or place of organization



Number of



owned by







  Sole voting power


  0 shares of Common Stock


  Shared voting power


  7,929,918 shares of Common Stock


  Sole dispositive power


  0 shares of Common Stock


  Shared dispositive power


  7,929,918 shares of Common Stock


  Aggregate amount beneficially owned by each reporting person


  7,929,918 shares of Common Stock


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




  Percent of class represented by amount in Row (11)




  Type of reporting person



This Amendment No. 4 to Schedule 13D relates to the Common Stock of Solid Biosciences Inc. and amends the initial statement on Schedule 13D filed by the Reporting Person on February 1, 2018, as amended by Amendment No. 1 filed on July 30, 2019, Amendment No. 2 filed on December 11, 2020 and Amendment No. 3 filed on March 25, 2021 (the “Initial Statement” and, as further amended by this Amendment No. 4, the “Schedule 13D”). Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Initial Statement.

Item 2. Identity and Background

Item 2 of the Initial Statement is hereby amended and restated as follows:

(a) This Schedule 13D is being filed by BCLS SB Investco, LP, a Delaware limited partnership (the “Reporting Person”).

Bain Capital Life Sciences Investors, LLC, a Delaware limited liability company (“BCLSI”), is the general partner of Bain Capital Life Sciences Partners, LP, a Cayman exempted limited partnership (“BCLSP” and, together with the Reporting Person and BCLSI, the “Bain Capital Life Sciences Entities”), which is the general partner of the Reporting Person. As a result, BCLSI may be deemed to share voting and dispositive power with respect to the securities held by the Reporting Person.

(b) The principal business address for each of the Bain Capital Life Sciences Entities is 200 Clarendon Street, Boston, MA 02116.

(c) Each of the Bain Capital Life Sciences Entities is principally engaged in the business of investment in securities.

(d) During the last five years, none of the Bain Capital Life Sciences Entities has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) During the last five years, none of the Bain Capital Life Sciences Entities has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violation of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

(f) The Reporting Person and BCLSI are organized under the laws of the State of Delaware. BCLSP is organized under the laws of the Cayman Islands.

Item 4. Purpose of Transaction

Item 4 of the Initial Statement is hereby amended and supplemented to add the following:

As previously disclosed by the Issuer, Dr. Adam Koppel, a Managing Director of BCLSI, did not stand for re-election to the Issuer’s board of directors (the “Board”) at the Issuer’s 2022 annual meeting of shareholders. Nevertheless, the Reporting Person is and will continue to be engaged collaboratively and constructively with the Issuer’s management and Board on operational, financial and/or strategic initiatives, including, without limitation, exploring, evaluating, proposing and/or negotiating one or more acquisitions and/or significant financing transactions in which the Reporting Person or its affiliates acquires additional securities of the Issuer and seeks to have one or more representatives serve on the

Board. The Reporting Person reviews and intends to continue to review, on an ongoing basis, its investment in the Issuer. Depending upon the factors discussed below and subject to applicable law, the Reporting Person may from time to time directly or indirectly acquire additional securities of the Issuer, sell or otherwise dispose of some or all of its securities of the Issuer and/or cease any of the activities described above. Any action taken by the Reporting Person may be made at any time and from time to time without prior notice and will depend on a variety of factors, including, without limitation, current and anticipated future trading prices of the securities of the Issuer, the financial condition, results of operations and prospects of the Issuer, available financing sources, general economic, financial market and industry conditions, other investment and business opportunities available to the Reporting Person, tax considerations and other factors.

Item 5. Interest in Securities of the Issuer

Item 5 of the Initial Statement is hereby amended and restated as follows:

The information set forth in or incorporated by reference in Items 2 and 3 and on the cover pages of this Schedule 13D is incorporated by reference in its entirety into this Item 5.


(a)  -

(c) As of the date hereof, the Reporting Person held 7,929,918 shares of Common Stock, representing approximately 7.0% of the Issuer’s outstanding shares of Common Stock. The percentage of the Issuer’s outstanding shares of Common Stock held by the Reporting Person is based on 112,989,773 shares of Common Stock outstanding as of August 8, 2022, as reported in the Issuer’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2022.



Except as otherwise described in this Item 5, no one other than the Reporting Person has the right to receive, or the power to direct the receipt of, dividends from, or the proceeds from the sale of, any of the Common Stock beneficially owned by the Reporting Person as described in this Item 5.



Not applicable.


After reasonable inquiry and to the best of its knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.


Dated: August 18, 2022     BCLS SB Investco, LP

Bain Capital Life Sciences Partners, LP,

its general partner


Bain Capital Life Sciences Investors, LLC,

its general partner


/s/ Adam Koppel

      Name: Adam Koppel
      Title: Managing Director