<SEC-DOCUMENT>0001193125-18-004354.txt : 20180223
<SEC-HEADER>0001193125-18-004354.hdr.sgml : 20180223
<ACCEPTANCE-DATETIME>20180105154202
<PRIVATE-TO-PUBLIC>
ACCESSION NUMBER:		0001193125-18-004354
CONFORMED SUBMISSION TYPE:	CORRESP
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20180105

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Solid Biosciences, LLC
		CENTRAL INDEX KEY:			0001707502
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				900943402

	FILING VALUES:
		FORM TYPE:		CORRESP

	BUSINESS ADDRESS:	
		STREET 1:		141 PORTLAND STREET, FIFTH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		617-337-4682

	MAIL ADDRESS:	
		STREET 1:		141 PORTLAND STREET, FIFTH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Solid Biosciences, LLC
		DATE OF NAME CHANGE:	20170524
</SEC-HEADER>
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<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="right"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>*FOIA&nbsp;Confidential&nbsp;Treatment&nbsp;Request*&nbsp;Confidential</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Treatment Requested by Solid Biosciences, LLC</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>in&nbsp;connection&nbsp;with&nbsp;its&nbsp;Registration&nbsp;Statement on</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Form S-1 filed on December 29, 2017</B></P></TD></TR>
</TABLE> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January&nbsp;5, 2018</P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Division of Corporation
Finance</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">100 F Street, N.E.</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Washington, D.C 20549</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">Julie M. Allen, Esq.</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">Member of the Firm</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">d
212.969.3155</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">f 212.969.2900</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">jallen@proskauer.com</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; margin-left:7.20em; font-size:10pt; font-family:Times New Roman">www.proskauer.com</P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left">Attn:</TD>
<TD ALIGN="left" VALIGN="top">Joseph McCann </TD></TR></TABLE>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left">&nbsp;&nbsp;&nbsp;&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">Christine Westbrook </TD></TR></TABLE>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="5%" VALIGN="top" ALIGN="left">&nbsp;&nbsp;&nbsp;&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">Kevin W. Vaughn </TD></TR></TABLE>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left">&nbsp;&nbsp;&nbsp;&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">Bonnie Baynes </TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left"><B>Re:</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Solid Biosciences Inc. </B></TD></TR></TABLE>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left"><B>&nbsp;&nbsp;&nbsp;&nbsp;</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Registration Statement on Form <FONT STYLE="white-space:nowrap">S-1</FONT> (No. <FONT STYLE="white-space:nowrap">333-222357)</FONT> </B></TD></TR></TABLE>
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<TD WIDTH="5%" VALIGN="top" ALIGN="left"><B>&nbsp;&nbsp;&nbsp;&nbsp;</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Filed on December&nbsp;29, 2017 </B></TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ladies and Gentlemen: </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On behalf of Solid Biosciences, LLC (the &#147;<B>Company</B>&#148;), we submit this supplemental letter to the staff (the
&#147;<B>Staff</B>&#148;)<B> </B>of the Securities and Exchange Commission (the &#147;<B>Commission</B>&#148;) relating to the above referenced registration statement of the Company confidentially submitted to the Commission on Form <FONT
STYLE="white-space:nowrap">S-1</FONT> on August&nbsp;4, 2017 and subsequently resubmitted on October&nbsp;20, 2017 and publicly filed on December&nbsp;29, 2017 (the &#147;<B>Registration Statement</B>&#148;). </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Because of the commercially sensitive nature of information contained herein, this submission is accompanied by the Company&#146;s request for
confidential treatment for selected portions of this letter. The Company has filed a separate letter with the Office of Freedom of Information and Privacy Act Operations in connection with the confidential treatment request, pursuant to Rule 83 of
the Commission&#146;s Rules on Information and Requests, 17 C.F.R. &#167;&nbsp;200.83. For the Staff&#146;s reference, we have enclosed a copy of the Company&#146;s letter to the Office of Freedom of Information and Privacy Act Operations, as well
as a copy of this correspondence, marked to show the portions redacted from the version filed via EDGAR and for which the Company is requesting confidential treatment. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company advises the Staff that the Company preliminarily estimates a price range (assuming a <FONT STYLE="white-space:nowrap"><FONT
STYLE="white-space:nowrap">one-to-one</FONT></FONT> conversion ratio of the Company&#146;s units to shares of common stock to be effective prior to the effectiveness of the Registration Statement) of approximately $[***] to $[***] per share (the
&#147;<B>Price Range</B>&#148;) for its initial public offering (&#147;<B>IPO</B>&#148;).<SUP STYLE="font-size:85%; vertical-align:top">1</SUP> This represents a <FONT STYLE="white-space:nowrap">pre-offering</FONT> equity value of the Company of
$[***] million to $[***]million. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">As is typical in IPOs, the Price Range was not derived using a formal determination of fair value, but
was determined by negotiations between the Company and the underwriters. </P> <P STYLE="line-height:8.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000;width:10%">&nbsp;</P>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><SUP STYLE="font-size:85%; vertical-align:top">1</SUP>&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The Company may adjust the <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">one-to-one</FONT></FONT> conversion ratio prior to the filing of an amendment to the Registration Statement that includes the
Price Range, in which case, proportionate changes would be made to the Price Range. </TD></TR></TABLE> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>

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 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">
Among the factors that were considered in setting the Price Range were: (i)&nbsp;the general conditions of the securities market and the recent market prices of, and the demand for, publicly
traded common stock of comparable companies: (ii)&nbsp;the Company&#146;s financial condition and prospects; (iii)&nbsp;estimates of business potential and earnings prospects for the Company and the industry in which it operates; (iv)&nbsp;recent
performance of IPOs of companies in the biotechnology sector; and (v)&nbsp;input received from the lead underwriters, including discussions that took place on December&nbsp;11, 2017 between senior management of the Company and representatives of
J.P. Morgan Securities LLC. The Price Range does not take into account the current lack of liquidity for the Company&#146;s Series D Common Units and assumes a successful IPO with no weighting attributed to any other outcome for the Company&#146;s
business, such as remaining a privately held company or being sold in an acquisition transaction. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company expects to include the
Price Range in an amendment to the Registration Statement that would shortly precede the commencement of the Company&#146;s road show. The Company confirms to the Staff that in accordance with Item 501(b)(3) of Regulation <FONT
STYLE="white-space:nowrap">S-K</FONT> and CD&amp;I 134.04, the Price Range will not be in excess of 20% of the high end of the range, as adjusted to give effect to any change in the conversion ratio. The parameters of the narrower price range to be
included in an amendment to the Registration Statement that would shortly precede the road show will be subject to then-current market conditions, continuing discussions with the underwriters and any business developments impacting the Company. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Equity-Based Compensation Transactions since January&nbsp;1, 2016 </U></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company is supplementally providing information and analysis with respect to equity-based compensation granted to employees and consultants
under its equity incentive plans since January&nbsp;1, 2016. The Company believes that this time period is relevant because it covers a period of more than 18 months prior to Company&#146;s initial confidential submission of the Registration
Statement to the Staff. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>Equity Awards Granted Prior to Merger and Recapitalization </I></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company adopted the Solid Ventures, LLC Equity Incentive Plan (the &#147;<B>Solid Ventures Plan</B>&#148;) on January&nbsp;1, 2015. Under
the Solid Ventures Plan, the Company granted restricted Series A Common Units to certain of its employees and consultants (the &#147;Series A Common Units&#148;). The Series A Common Units are designated as &#147;profit interests&#148; as the common
units receive distributions only if a certain threshold, which was set to equal the then total fair value of the Company&#146;s equity as of the grant date for such grant (the &#147;<B>Applicable Grant Date Threshold</B>&#148;), is exceeded. The
Applicable Grant Date Threshold impacts the fair value of the Company&#146;s Series A Common Units because distributions, if any, are made in accordance with the priorities set forth in the Company&#146;s limited liability company agreement. Series
A Common Units with a lower Applicable Grant Date Threshold are entitled to receive distributions before Series A Common Unit holders with a higher Applicable Grant Date Threshold. </P>
<p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>

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 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 3
 </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In order to equate the value of these Series A Common Units to the common stock of a
corporation, the Company believes that the appropriate comparison is to the fair value of the Series A Common Units, as of each respective grant date, at a zero threshold level (the &#147;<B>Zero Threshold</B>&#148;) because the Applicable Grant
Date Thresholds and the distribution preferences will terminate upon the Company&#146;s conversion to a corporation. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The table below sets
forth a summary of the Series A Common Units granted under the Solid Ventures Plan, since January&nbsp;1, 2016. Included in the summary table is the Applicable Grant Date Threshold, the per unit fair value at the Zero Threshold and the per unit fair
value at the Applicable Grant Date Threshold. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" ROWSPAN="3" ALIGN="center"><FONT STYLE="font-size:8pt"><B>Grant Date</B></FONT></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="7" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Original Issuance</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Solid Biosciences, LLC &#150; <BR>Series A Common Units)</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="7" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>After Giving Effect to Merger and Recapitalization</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Solid Biosciences, LLC &#150; <BR>Series D Common Units)</B></P></TD></TR>
<TR STYLE="font-size:1px; ">
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD COLSPAN="7" VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD COLSPAN="7" VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Applicable<BR>Grant Date<BR>Threshold<BR>(millions)</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair Value&nbsp;<BR>per Unit at<BR>Zero<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Number of<BR>Units<BR>Underlying<BR>Grants</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair&nbsp;Value&nbsp;<BR>per Unit at<BR>Applicable<BR>Grant Date<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Applicable<BR>Grant Date<BR>Threshold<BR>(millions)</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair Value&nbsp;<BR>per Unit at<BR>Zero<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Number of<BR>Units<BR>Underlying<BR>Grants</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair&nbsp;Value&nbsp;<BR>per Unit at<BR>Applicable<BR>Grant Date<BR>Threshold</B></TD></TR>
<TR STYLE="font-size:1px; ">
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">01/29/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">05/12/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">09/14/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">12/06/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On March&nbsp;29, 2017, in connection with the Company&#146;s merger with Solid GT, LLC (&#147;<B>Solid
GT</B>&#148;) and its concurrent recapitalization (collectively, the &#147;<B>Merger and Recapitalization</B>&#148;), the Company amended the Solid Ventures Plan and changed the name of the Solid Ventures Plan to the Solid Biosciences, LLC Amended
and Restated Equity Incentive Plan (the &#147;<B>Amended Plan</B>&#148;). On such date, all of the Company&#146;s Series A Common Units included in the table above were exchanged for Series D Common Units. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Under the Solid GT LLC Agreement, Solid GT granted Class&nbsp;C Restricted Common Units to certain of its employees and consultants. Solid
GT&#146;s Class&nbsp;C Restricted Common Units are similar to the Company&#146;s Series A Common Units as the Class&nbsp;C Restricted Common Units are also designated as &#147;profit interests&#148; and the Applicable Grant Date Threshold for each
grant of Solid GT Class&nbsp;C Restricted Common Units was set to equal the then total fair value of Solid GT&#146;s equity as of the grant date for such grant. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The table below sets forth a summary of the Class&nbsp;C Restricted Common Units granted under the Solid GT LLC Agreement, since
January&nbsp;1, 2016. Included in the summary table is the Applicable Grant Date Threshold, the per unit fair value at the Zero Threshold and the per unit fair value at the Applicable Grant Date Threshold. </P>
<p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>

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<IMG SRC="g404258g51i15.gif" ALT="LOGO">
 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 4
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<TD WIDTH="13%"></TD>
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<TD WIDTH="7%"></TD>
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<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ROWSPAN="3" ALIGN="center"><FONT STYLE="font-size:8pt"><B>Grant Date</B></FONT></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="7" ALIGN="center"><FONT STYLE="font-size:8pt"><B>Original Issuance Amounts<BR>(Solid GT, LLC &#150; <BR>Class&nbsp;C Restricted Common Units)</B></FONT></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="7" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>After Giving Effect to Merger and Recapitalization</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Solid Biosciences, LLC &#150; <BR>Series D Common Units)</B></P></TD></TR>
<TR STYLE="font-size:1px; ">
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD COLSPAN="7" VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD COLSPAN="7" VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Applicable<BR>Grant Date<BR>Threshold<BR>(millions)</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair Value&nbsp;<BR>per Unit at<BR>Zero<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Number of<BR>Units<BR>Underlying<BR>Grants</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair&nbsp;Value&nbsp;<BR>per Unit at<BR>Applicable<BR>Grant Date<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Applicable<BR>Grant Date<BR>Threshold<BR>(millions)</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair Value&nbsp;<BR>per Unit at<BR>Zero<BR>Threshold</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Number of<BR>Units<BR>Underlying<BR>Grants</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Fair&nbsp;Value&nbsp;<BR>per Unit at<BR>Applicable<BR>Grant Date<BR>Threshold</B></TD></TR>
<TR STYLE="font-size:1px; ">
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">01/04/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">03/23/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">05/12/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">08/22/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">09/14/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center">12/06/2016</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">[***]</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center">$[***]</TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On March&nbsp;29, 2017, in connection with the Merger and Recapitalization, all Class&nbsp;C Restricted Common
Units of Solid GT were exchanged for Series D Common Units of the Company as indicated in the table above. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>Equity Awards Granted Subsequent to Merger
and Recapitalization </I></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Under the Amended Plan, the Company granted Series D Common Units to certain of its employees and consultants.
The table below sets forth a summary of the equity awards granted under the Amended Plan, since March&nbsp;29, 2017. Included in the summary table is the Applicable Grant Date Threshold, the per unit fair value at the Zero Threshold and the per unit
fair value at the Applicable Grant Date Threshold. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="18%"></TD>
<TD VALIGN="bottom"></TD>
<TD WIDTH="19%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="20%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="20%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="19%"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ROWSPAN="2" NOWRAP ALIGN="center"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; border-bottom:1.00pt solid #000000; width:38.85pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Grant Date</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ROWSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Applicable Grant Date<BR>Threshold</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(millions)</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="5" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Solid Biosciences, LLC &#150; Series D Common
Units</B></P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Fair Value&nbsp;<BR>per Unit at Zero Threshold</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Number of Units Underlying<BR>Grants</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Fair&nbsp;Value&nbsp;<BR>per Unit at Applicable Grant<BR>Date
Threshold</B></P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>03/29/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>05/31/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>06/01/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>06/12/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>06/19/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>07/10/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>07/17/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>08/01/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>09/12/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>09/20/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>10/05/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom" ALIGN="center"><B>12/7/2017</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>[***]</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>$[***]</B></TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential
treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>

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<IMG SRC="g404258g51i15.gif" ALT="LOGO">
 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 5
 </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company has not granted any additional equity awards since December&nbsp;7, 2017. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Company Methodology in Determining Fair Value </U></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">As described beginning on page 73 of the Registration Statement, the Company regularly performs contemporaneous valuations of its units to
assist the Company&#146;s Board of Managers (the &#147;<B>Board</B>&#148;) in determining the fair value of the common units for purposes of granting equity-based awards. The Board has generally considered numerous objective and subjective factors,
including the factors set forth on page 74 of the Registration Statement, and contemporaneous reports prepared by an independent third-party valuation specialist. As disclosed in the Registration Statement, the Company&#146;s common unit valuations
were prepared using a market approach based on the most recent rounds of equity financing and an option pricing method (&#147;<B>OPM</B>&#148;), with the exception of the December&nbsp;6, 2016 valuation, which was performed using the hybrid method
and the expected probability of closing a financing round. The hybrid method was used in anticipation of an anticipated equity financing transaction, which had not closed as of the valuation date. The OPM treats common units and preferred units as
call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the various holders of a company&#146;s securities changes. Under this method, the common unit has value only if
the funds available for distribution to stockholders exceed the value of the preferred stock liquidation preference at the time of the liquidity event, such as a strategic sale, merger or public offering. The hybrid method is a probability-weighed
expected return method (&#147;<B>PWERM</B>&#148;) where the equity value in one or more scenarios is calculated using an OPM. The PWERM is a scenario-based methodology that estimates the fair value of common units based upon an analysis of future
values for the Company, assuming various outcomes. The common unit value is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes available as well as the rights of each class
of units. The values of the common unit under each outcome are probability weighted to arrive at an indication of value for the common unit. The OPM and hybrid methods were selected to properly account for the Company&#146;s limited liability
company structure, in which the value of the units received in a waterfall scenario is contractually preserved in all exit scenarios, including the initial public offering. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In addition to assumptions related to the allocation of value between different classes of securities, the valuation analyses also considered
changes in the value of equity of the Company between the different measurement dates.&nbsp;Specifically, the valuation analyses considered any Company-specific factors that may have occurred between valuation dates, as well as market-driven changes
in value.&nbsp;The Company-specific factors were based on discussions with the Company&#146;s management and review of documents, as applicable.&nbsp;The market-driven changes in value were based on changes in value of the Nasdaq Biotechnology Index
as well as consideration of the relative importance of Company-specific and market-driven factors.&nbsp;In the valuations, a portion of the change in value of the Nasdaq Biotechnology Index was reflected in the valuation directly by adjusting the
equity value between measurement dates. </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested
pursuant to 17 C.F.R. &#167;200.83. </B></P>

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<IMG SRC="g404258g51i15.gif" ALT="LOGO">
 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 6
 </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In connection with the valuation reports prepared by an unrelated third-party valuation
specialist, the Board has also determined that the assumptions and inputs used in connection with such contemporaneous valuations reflect the Board&#146;s and management&#146;s best estimate of the business condition, prospects and operating
performance of the Company at each valuation date. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Factors Contributing to the Difference </U><U>Between</U><U> the Grant Date Estimated Fair Value
and the Price Range</U> </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">As discussed above, the Company&#146;s Series D Common Units do not result in any value to the holder until a
certain threshold of the total fair value of the Company is met, similar to an option exercise price. The threshold for each grant of Series D Common Units was set to equal the then total fair value of the Company&#146;s equity as of the grant date
for such grant. As a result, the Company believes it is appropriate to compare the fair value of the Company&#146;s Series D Common Units at Zero Threshold to the Price Range. Similarly, the total fair value of the Company&#146;s equity at such
grant date may be compared with the estimated <FONT STYLE="white-space:nowrap">pre-offering</FONT> equity value of the Company, estimated to be between $[***] million and $[***] million. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On October&nbsp;26, 2017, the Company sold Series 2 Senior Preferred Units at a price of $11.26 per unit raising net proceeds of
$55.0&nbsp;million. The Company and its Board believe that the price for the Series 2 Senior Preferred Units of $11.26 provides evidence of a freely negotiated, <FONT STYLE="white-space:nowrap">arm&#146;s-length</FONT> transaction with knowledgeable
buyers. The Series 2 Senior Preferred Units retained preferences over the Company&#146;s Series D Common Units, pursuant to the Company&#146;s limited liability company agreement, resulting in a difference in the purchase price of the Series 2
Senior Preferred Units and fair value of the Series D Common Units. The Company had a third-party valuation performed in conjunction with the Series 2 Preferred Unit financing which indicated a fair value of the Company&#146;s Common Units at Zero
Threshold to be $[***] per unit. The third-party valuation used a post-offering equity value of the Company of approximately $[***] million. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Company believes that the differences between the October&nbsp;26, 2017 valuation, which reflects a total equity value of approximately
$[***] million and a fair value of the Series D Common Units at Zero Threshold of $[***] per unit, and the estimated Price Range are primarily the result of the following factors: </P>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The Price Range represents a future price for the Company&#146;s shares of common stock that, if issued in the IPO, will be immediately freely tradable in a public market, whereas the estimated fair value of the
Company&#146;s Series D Common Units represented a contemporaneous estimate of the fair value of the Series D Common Units that were then illiquid, might never become liquid, might be for units that are never publicly traded and, even if an IPO is
successfully completed, would remain illiquid at least until the expiration of the <FONT STYLE="white-space:nowrap">180-day</FONT> <FONT STYLE="white-space:nowrap">lock-up</FONT> period following the IPO. Accordingly, the Company&#146;s valuation
analysis, as of October&nbsp;26, 2017, appropriately applied a discount for lack of marketability for a <FONT STYLE="white-space:nowrap">non-controlling</FONT> interest in the Series D Common Units. </TD></TR></TABLE>
<p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>

<p Style='page-break-before:always'>
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 <P STYLE="margin-top:0pt;margin-bottom:0pt">


<IMG SRC="g404258g51i15.gif" ALT="LOGO">
 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 7
 </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>

<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The Price Range represents a future price for the Company&#146;s shares of common stock that, if issued in the IPO, will have voting rights whereas the estimated fair value of the Company&#146;s Series D Common Units
represented a contemporaneous estimate of the fair value that did not have voting rights. Accordingly, the Company&#146;s analysis, as of October&nbsp;26, 2017, appropriately applied a discount for lack of voting rights for the Company&#146;s Series
D Common Units. </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">If the October&nbsp;26, 2017 valuation did not apply a discount for lack of marketability for a <FONT STYLE="white-space:nowrap">non-controlling</FONT> interest or lack of voting rights for the Company&#146;s Series D
Common units, the fair value of the Company&#146;s Series D Common Units at Zero Threshold would be approximately $[***]. In addition, if this valuation had been done assuming that the Company had converted to a corporation and that the preferred
unit holders forfeited their liquidation preferences, the fair value of the Company&#146;s Series D Common Units at Zero Threshold would be $[***] per unit. </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The Price Range represents a future price for the Company&#146;s shares of common stock that, if issued in the IPO, will give effect to the Company&#146;s conversion from a limited liability company to a corporation,
which will result in the conversion of all outstanding preferred units and common units of the Company into a single class of common stock and the termination of the Company&#146;s limited liability company structure and the related waterfall
scenario of liquidation and distribution preferences (including the applicable thresholds on the Series D Common Units) that are set forth in the Company&#146;s limited liability company agreement. </TD></TR></TABLE>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">In determining the Price Range, the Company considered the median step up in valuation of 15 recent biotechnology initial public offerings and their respective prior financing rounds. </TD></TR></TABLE>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The Company received positive feedback during <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">&#147;testing-the-waters&#148;</FONT></FONT> meetings which occurred late in 2017. These meetings
reinforced the Company&#146;s belief that investors view the Company as having made significant and continued progress through 2017. </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="5%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top">The successful completion of the IPO would strengthen the Company&#146;s balance sheet and provide the Company with access to the public company equity and debt markets to fund the research and development of its
product candidates. </TD></TR></TABLE> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested
pursuant to 17 C.F.R. &#167;200.83. </B></P>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


 <P STYLE="margin-top:0pt;margin-bottom:0pt">


<IMG SRC="g404258g51i15.gif" ALT="LOGO">
 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">U.S. Securities and Exchange Commission </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">January 5, 2018 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"> Page
 8
 </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Please contact me at (212) <FONT STYLE="white-space:nowrap">969-3155</FONT> with any
questions or further comments regarding our response to the Staff&#146;s comment. </P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="100%"></TD></TR>


<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Sincerely,</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000">/s/ Julie Allen</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Julie Allen, Esq.</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Proskauer Rose
LLP</P></TD></TR>
</TABLE> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">cc:</TD>
<TD ALIGN="left" VALIGN="top">Ilan Ganot, Solid Biosciences, LLC </TD></TR></TABLE> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Jennifer Ziolkowski, Solid Biosciences, LLC </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Daniel Finkelman, Solid Biosciences, LLC </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Daniel Forman, Proskauer Rose LLP </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Deanna Kirkpatrick, Davis Polk&nbsp;&amp; Wardwell LLP </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:4%; font-size:10pt; font-family:Times New Roman">Yasin Keshvargar, Davis Polk&nbsp;&amp; Wardwell LLP </P> <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>[***] Confidential treatment requested pursuant to 17 C.F.R. &#167;200.83. </B></P>
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end
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
