<SEC-DOCUMENT>0001047469-18-004590.txt : 20180620
<SEC-HEADER>0001047469-18-004590.hdr.sgml : 20180620
<ACCEPTANCE-DATETIME>20180620060447
ACCESSION NUMBER:		0001047469-18-004590
CONFORMED SUBMISSION TYPE:	S-1MEF
PUBLIC DOCUMENT COUNT:		6
<REFERENCE-462B>333-225410
FILED AS OF DATE:		20180620
DATE AS OF CHANGE:		20180620
EFFECTIVENESS DATE:		20180620

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CATABASIS PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0001454789
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		S-1MEF
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-225734
		FILM NUMBER:		18908591

	BUSINESS ADDRESS:	
		STREET 1:		ONE KENDALL SQUARE
		STREET 2:		BLDG. 1400E, SUITE B14202
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		617-349-1971

	MAIL ADDRESS:	
		STREET 1:		ONE KENDALL SQUARE
		STREET 2:		BLDG. 1400E, SUITE B14202
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-1MEF
<SEQUENCE>1
<FILENAME>a2236069zs-1mef.htm
<DESCRIPTION>S-1MEF
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</FONT> <FONT SIZE=1><B>As Filed with the Securities and Exchange Commission on June&nbsp;20, 2018  </B></FONT></P>

<P ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=1><B> Registration No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</B></FONT></P>

<P style="font-family:times;"><FONT SIZE=1><B><BR>  </B></FONT></P>

<P style="font-family:times;"><FONT SIZE=1><B> <div style="width:100%;border-top:solid #000000 3.0pt;padding:0in 0in 0in 0in;font-size:3.0pt;"></div>
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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=4><B>UNITED STATES<BR>
SECURITIES AND EXCHANGE COMMISSION<BR>  </B></FONT><FONT SIZE=1><B>Washington, D.C. 20549  </B></FONT></P>

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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=4><B>FORM S-1<BR>  </B></FONT><FONT SIZE=1><B>REGISTRATION STATEMENT<BR>
UNDER<BR>
THE SECURITIES ACT OF&nbsp;1933  </B></FONT></P>

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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=4><B>CATABASIS PHARMACEUTICALS,&nbsp;INC.<BR>  </B></FONT><FONT SIZE=1>(Exact name of registrant as specified in its charter) </FONT></P>

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<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Delaware<BR> </B></FONT><FONT SIZE=1>(State or other jurisdiction<BR>
of&nbsp;incorporation or organization)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B> 2834</B></FONT><FONT SIZE=1><BR>
(Primary Standard<BR>
Industrial&nbsp;Classification&nbsp;Code&nbsp;Number)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B> 26-3687168</B></FONT><FONT SIZE=1><BR>
(I.R.S. Employer<BR>
Identification No.)</FONT></TD>
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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>One Kendall Square<BR>
Bldg. 1400E, Suite B14202<BR>
Cambridge, Massachusetts 02139<BR>
(617)&nbsp;349-1971</B></FONT><FONT SIZE=1><BR>
(Address, including zip code, and telephone number, including area code, of registrant's principal executive offices) </FONT></P>

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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Jill C. Milne, Ph.D.<BR>
President and Chief Executive Officer<BR>
Catabasis Pharmaceuticals,&nbsp;Inc.<BR>
One Kendall Square<BR>
Bldg. 1400E, Suite B14202<BR>
Cambridge, Massachusetts 02139<BR>
(617)&nbsp;349-1971<BR>  </B></FONT><FONT SIZE=1>(Name, address, including zip code, and telephone number, including area code, of agent for service) </FONT></P>

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<TD COLSPAN=3 ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Copies to:</B></FONT></TD>
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<TD ALIGN="CENTER" style="font-family:times;"><BR><FONT SIZE=1><B>Rosemary G. Reilly, Esq.<BR>
WilmerHale<BR>
60 State Street<BR>
Boston, MA 02109<BR>
Telephone: (617)&nbsp;526-6000<BR>
Fax: (617)&nbsp;526-5000</B></FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1><B><BR>&nbsp;</B></FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B><BR>
John D. Hogoboom<BR>
Lowenstein Sandler&nbsp;LLP<BR>
1251 Avenue of the Americas<BR>
New York, NY 10020<BR>
Telephone: (212)&nbsp;262-6700<BR>
Fax: (212)&nbsp;262-7402<BR> </B></FONT></TD>
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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this Registration Statement.  </B></FONT></P>


<P style="font-family:times;"><FONT SIZE=1>If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule&nbsp;415 under the Securities Act of 1933, check the
following box.&nbsp;&nbsp;&nbsp;&nbsp;<FONT FACE="WINGDINGS">&#253;</FONT> </FONT></P>

<P style="font-family:times;"><FONT SIZE=1>If this Form is filed to register additional securities for an offering pursuant to Rule&nbsp;462(b) under the Securities Act, check the following box and list the Securities
Act registration statement number of the earlier effective registration statement for the same offering.&nbsp;&nbsp;&nbsp;&nbsp;<FONT FACE="WINGDINGS">&#253;</FONT>&nbsp;&nbsp;333-225410 </FONT></P>

<P style="font-family:times;"><FONT SIZE=1>If this Form is a post-effective amendment filed pursuant to Rule&nbsp;462(c) under the Securities Act, check the following box and list the Securities Act registration
statement number of the earlier effective registration statement for the same offering.&nbsp;&nbsp;&nbsp;&nbsp;<FONT FACE="WINGDINGS">&#111;</FONT> </FONT></P>

<P style="font-family:times;"><FONT SIZE=1>If this Form is a post-effective amendment filed pursuant to Rule&nbsp;462(d) under the Securities Act, check the following box and list the Securities Act registration
statement number of the earlier effective registration statement for the same offering.&nbsp;&nbsp;&nbsp;&nbsp;<FONT FACE="WINGDINGS">&#111;</FONT> </FONT></P>

<P style="font-family:times;"><FONT SIZE=1>Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth
company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule&nbsp;12b-2 of the Exchange Act. </FONT></P>
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<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>Large accelerated filer&nbsp;<FONT FACE="WINGDINGS">&#111;</FONT></FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>Accelerated&nbsp;filer&nbsp;<FONT FACE="WINGDINGS">&#111;</FONT></FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>Non-accelerated filer&nbsp;<FONT FACE="WINGDINGS">&#253;</FONT><BR></FONT> <FONT SIZE=1>(Do not check if a<BR>
smaller reporting company)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;text-align:center;"><FONT SIZE=1>


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 Smaller reporting company&nbsp;<FONT FACE="WINGDINGS">&#111;</FONT></font> <p align=center style="font-family:times;margin-top:0pt;margin-left:0pt;"> <FONT SIZE=1> Emerging growth company&nbsp;<FONT FACE="WINGDINGS">&#253;</FONT></FONT></TD>
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 <P style="font-family:times;"><FONT SIZE=1>If
an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards
provided pursuant to Section&nbsp;7(a)(2)(B) of the Securities Act.&nbsp;<FONT FACE="WINGDINGS">&#253;</FONT> </FONT></P>

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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>CALCULATION OF REGISTRATION FEE  </B></FONT></P>
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<TD VALIGN="BOTTOM" style="font-family:times;"><p style="font-family:times;margin-left:3pt;text-indent:-3pt;"><FONT SIZE=1> </FONT></TD>
<TD VALIGN="BOTTOM" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD VALIGN="BOTTOM" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD VALIGN="BOTTOM" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD VALIGN="BOTTOM" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
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<TH ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Title of Each Class of Securities<BR>
to be Registered</B></FONT><BR></TH>
<TH style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Proposed&nbsp;Maximum<BR>
Aggregate Offering<BR>
Price(1)(2)</B></FONT><BR></TH>
<TH style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1><B>Amount of<BR>
Registration Fee</B></FONT><BR></TH>
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<TD COLSPAN=5 VALIGN="BOTTOM" style="font-family:times;border-bottom:solid #000000 1.0pt;">&nbsp;</TD>
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<TD style="font-family:times;"><p style="font-family:times;margin-left:3pt;text-indent:-3pt;"><FONT SIZE=1><B> </B></FONT><FONT SIZE=1>Common Units, each Common Unit consisting of one share of common stock, par value $0.001 per share, and one warrant to purchase one share of common
stock</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$7,000,000</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$872</FONT></TD>
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<TD style="font-family:times;"><p style="font-family:times;margin-left:10pt;text-indent:-3pt;"><FONT SIZE=1> </FONT><FONT SIZE=1>(i) Common stock included in the Common Units(3)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
</TR>
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<TD COLSPAN=5 VALIGN="BOTTOM" style="font-family:times;border-bottom:solid #000000 1.0pt;">&nbsp;</TD>
</TR>
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<TD style="font-family:times;"><p style="font-family:times;margin-left:10pt;text-indent:-3pt;"><FONT SIZE=1> </FONT><FONT SIZE=1>(ii) Warrants included in the Common Units(3)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
</TR>
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<TD COLSPAN=5 VALIGN="BOTTOM" style="font-family:times;border-bottom:solid #000000 1.0pt;">&nbsp;</TD>
</TR>
<TR VALIGN="BOTTOM">
<TD style="font-family:times;"><p style="font-family:times;margin-left:3pt;text-indent:-3pt;"><FONT SIZE=1> </FONT><FONT SIZE=1>Shares of common stock underlying Warrants included in the Common Units(4)</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$8,400,000</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$1,046</FONT></TD>
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<TD COLSPAN=5 VALIGN="BOTTOM" style="font-family:times;border-bottom:solid #000000 1.0pt;">&nbsp;</TD>
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<TD style="font-family:times;"><p style="font-family:times;margin-left:10pt;text-indent:-3pt;"><FONT SIZE=1> </FONT><FONT SIZE=1>Total</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$15,400,000</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><FONT SIZE=1>$1,918</FONT></TD>
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<TD COLSPAN=5 VALIGN="BOTTOM" style="font-family:times;border-bottom:double #000000 2.25pt;"><p style="font-family:times;margin-left:3pt;text-indent:-3pt;"> &nbsp;</TD>
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<DT style='font-family:times;margin-bottom:-9pt;'><FONT SIZE=1>(1)</FONT></DT><DD style="font-family:times;"><FONT SIZE=1>Estimated
solely for the purpose of calculating the registration fee pursuant to Rule&nbsp;457(o) under the Securities Act of 1933, as amended. Represents only the
additional number of securities being registered. Does not include the securities that the registrant previously registered on the registration statement on Form S-1 (File No. 333-225410). </FONT></DD><DT style='font-family:times;margin-bottom:-9pt;'><FONT SIZE=1>(2)</FONT></DT><DD style="font-family:times;"><FONT
SIZE=1>Pursuant
to Rule&nbsp;416(a) under the Securities Act of 1933, as amended, this registration statement shall also cover an indeterminate number of shares that may
be issued and resold resulting from stock splits, stock dividends or similar transactions.  </FONT></DD><DT style='font-family:times;margin-bottom:-9pt;'><FONT SIZE=1>(3)</FONT></DT><DD style="font-family:times;"><FONT SIZE=1>Filing
fee included with the Common Units.  </FONT></DD><DT style='font-family:times;margin-bottom:-9pt;'><FONT SIZE=1>(4)</FONT></DT><DD style="font-family:times;"><FONT SIZE=1>Pursuant
to Staff Compliance and Disclosure Interpretation 240.06, equals the aggregate exercise price of the Warrants.  </FONT></DD></DL>

<P style="font-family:times;"><FONT SIZE=1><B>This Registration Statement shall become effective upon filing in accordance with Rule 462(b) under the Securities Act of 1933, as amended.</B></FONT></P>
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<A NAME="toc_bb49607_1"> </A>
<BR></FONT><FONT SIZE=3><B>  EXPLANATORY NOTE AND INCORPORATION BY REFERENCE  <BR>  </B></FONT></P>

<P style="font-family:times;"><FONT SIZE=2>This registration statement is being filed with respect to the registration of additional common units (each a "Common Unit"), each Common
Unit consisting of one share of common stock, $0.001 par value per share (each a "Share") and a warrant to purchase one Share, of the Registrant, as set forth in the Registration Statement and the
prospectus contained therein, of Catabasis Pharmaceuticals,&nbsp;Inc., a Delaware corporation, pursuant to Rule&nbsp;462(b) under the Securities Act of 1933, as amended. The contents of the
earlier registration statement on Form&nbsp;S-1 (File No.&nbsp;333-225410), which was declared effective by the Commission on June&nbsp;19, 2018, are incorporated in this registration statement
by reference. </FONT></P>


<P style="font-family:times;"><FONT SIZE=2>The
required opinions and consents are listed on an Exhibit Index attached hereto and filed herewith. </FONT></P>

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NAME="ja49607_exhibit_index"> </A>
<A NAME="toc_ja49607_1"> </A>
<BR></FONT><FONT SIZE=3><B>  EXHIBIT INDEX  <BR>  </B></FONT></P>
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<TH COLSPAN=2 ALIGN="CENTER" style="font-family:times;border-bottom:solid #000000 1.0pt;"><FONT SIZE=1><B>Exhibit<BR>
Number </B></FONT></TH>
<TH style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH ALIGN="CENTER" style="font-family:times;border-bottom:solid #000000 1.0pt;"><FONT SIZE=1><B>Description of Exhibit </B></FONT></TH>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=2>5.1</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><A HREF="a2236069zex-5_1.htm">Opinion of Wilmer Cutler Pickering Hale and Dorr&nbsp;LLP</A></FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=2>23.1</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><A HREF="a2236069zex-23_1.htm">Consent of Ernst&nbsp;&amp; Young&nbsp;LLP, independent registered public accounting firm</A></FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=2>23.2</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><A HREF="a2236069zex-5_1.htm">Consent of Wilmer Cutler Pickering Hale and Dorr&nbsp;LLP (included in Exhibit&nbsp;5.1)</A></FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=2>24.1</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>*</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><A HREF="http://www.sec.gov/Archives/edgar/data/1454789/000104746918004247/a2235913zs-1.htm#sig">Power of Attorney</A></FONT></TD>
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<DT style='font-family:times;margin-bottom:-9pt;'><FONT SIZE=1>*</FONT></DT><DD style="font-family:times;"><FONT SIZE=1>Filed
as Exhibit&nbsp;24.1 to the Registrant's Registration Statement on Form&nbsp;S-1 (File No.&nbsp;333-225410) filed with the Commission on June&nbsp;4,
2018. </FONT></DD></DL>
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<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=3><B> <A NAME="sig"></A>SIGNATURES  </B></FONT></P>

<P style="font-family:times;"><FONT SIZE=2>Pursuant to the requirements of the Securities Act of 1933, the registrant has duly caused this Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on this 20<SUP>th</SUP> day of June, 2018. </FONT></P>
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<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD COLSPAN=3 style="font-family:times;"><FONT SIZE=2>Catabasis Pharmaceuticals,&nbsp;Inc.</FONT></TD>
</TR>
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<TD style="font-family:times;"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD style="font-family:times;"><BR><FONT SIZE=2>By:</FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><BR><FONT SIZE=2>/s/&nbsp;JILL C. MILNE<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Jill C. Milne<BR></FONT> <FONT SIZE=2><I>President and Chief Executive Officer</I></FONT></TD>
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 <P style="font-family:times;"><FONT SIZE=2>Pursuant
to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated. </FONT></P>
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<TH style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TH>
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<TH style="font-family:times;"><FONT SIZE=1>&nbsp;</FONT></TH>
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<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2>/s/&nbsp;JILL C. MILNE<BR>



<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Jill C. Milne</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2>President and Chief Executive Officer and Director (Principal Executive Officer)</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
/s/&nbsp;DEIRDRE CUNNANE<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Deirdre Cunnane</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Chief Legal Officer and Treasurer (Principal Financial Officer)</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
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<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
/s/&nbsp;NOAH CLAUSER<BR>


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</FONT> <FONT SIZE=2> Noah Clauser</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Vice President of Finance (Principal Accounting Officer)</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
*<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Michael Ross</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Co-Chairman of the Board of Directors</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
*<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Kenneth Bate</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Co-Chairman of the Board of Directors</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
*<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Burt Adelman</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Director</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
*<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Jean George</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Director</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD COLSPAN=3 ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>
*<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Michael Kishbauch</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>Director</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>June&nbsp;20, 2018</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>*By:</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" style="font-family:times;"><BR><FONT SIZE=2>/s/&nbsp;DEIRDRE A. CUNNANE<BR>


<HR NOSHADE SIZE="1.0pt" WIDTH="100%" COLOR="#000000">

</FONT> <FONT SIZE=2> Deirdre A. Cunnane<BR></FONT> <FONT SIZE=2><I>Attorney-in-fact</I></FONT></TD>
<TD style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>&nbsp;</FONT></TD>
<TD VALIGN="MIDDLE" style="font-family:times;"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD ALIGN="CENTER" VALIGN="MIDDLE" style="font-family:times;"><BR><FONT SIZE=2>&nbsp;</FONT></TD>
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<P><br><A NAME="18ZBT49607_1">QuickLinks</A><br></P><!-- TOC_BEGIN -->
<FONT SIZE=2 style="font-family:times;"><A HREF="#toc_bb49607_1">EXPLANATORY NOTE AND INCORPORATION BY REFERENCE</A></FONT><BR>
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<FONT SIZE=2 style="font-family:times;"><A HREF="#toc_ja49607_1">EXHIBIT INDEX</A></FONT><BR>

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<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>a2236069zex-5_1.htm
<DESCRIPTION>EX-5.1
<TEXT>
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<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Exhibit&nbsp;5.1</font></b><a name="14696-2-KQ_Exhibit5_1_102459"></a></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman"><img width="123" height="16" src="g146962kqi001.gif"></font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman"><img width="81" height="34" src="g146962kqi002.gif"></font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">June&nbsp;20, 2018</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Catabasis Pharmaceuticals,&nbsp;Inc.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">One Kendall Square</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Building 1400E, Suite&nbsp;B14202</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Cambridge, Massachusetts 02139</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Re:&nbsp;&nbsp; <u>Registration Statement on Form&nbsp;S-1</u></font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Ladies and Gentlemen:</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This opinion is furnished to you in connection with &nbsp;the Registration Statement on Form&nbsp;S-1 (the &#147;Registration Statement&#148;) filed by Catabasis Pharmaceuticals,&nbsp;Inc., a Delaware corporation (the &#147;Registrant&#148;), with the Securities and Exchange Commission (the &#147;Commission&#148;) under the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), pursuant to Rule 462(b) of the Securities Act, for the purpose of registering with the Commission under the Securities Act a proposed maximum aggregate offering price of $15,400,000 of common units (each a &#147;Common Unit&#148;), each Common Unit consisting of one share of common stock, $0.001 par value per share (each a &#147;Share&#148;) and a warrant to purchase one Share (each a &#147;Common Warrant&#148; and each Share underlying a Common Warrant, a &#147;Common Warrant Share&#148;) of the Registrant, as set forth in the Registration Statement and the prospectus contained therein. The Common Units, the Shares, the Common Warrants and the Common Warrant Shares are collectively referred to as the &#147;Securities.&#148;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The Securities are to be sold by the Registrant pursuant to an underwriting agreement (the &#147;Underwriting Agreement&#148;) entered into by and among the Registrant and Oppenheimer&nbsp;&amp; Co. Inc., as the sole underwriter, the form of which has been incorporated by reference into the Registration Statement.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">We are acting as counsel for the Registrant in connection with the issue and sale by the Registrant of the Securities.&#160; We have examined signed copies of the Registration Statement as filed with the Commission.&#160; We have also examined and relied upon the Underwriting Agreement, minutes of meetings and actions of the stockholders and the Board of Directors of the Registrant as provided to us by the Registrant, stock record books of the Registrant as provided to us by the Registrant, the Certificate of Incorporation and By-laws of the Registrant, each as restated and/or amended to date, and such other documents as we have deemed necessary for purposes of rendering the opinions hereinafter set forth.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as copies, the authenticity of the originals of such latter documents and the legal competence of all signatories to such documents.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Our opinions set forth below are qualified to the extent that they may be subject to or affected by (i)&nbsp;applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or similar laws relating to or affecting the rights of creditors generally, (ii)&nbsp;statutory or decisional law concerning recourse by creditors to security in the absence of notice or hearing, (iii)&nbsp;duties and standards imposed on creditors and parties to contracts, including,</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman"><img width="622" height="26" src="g146962kqi003.gif"></font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<div style="font-family:Times New Roman;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">without limitation, requirements of good faith, reasonableness and fair dealing, and (iv)&nbsp;general equitable principles.&#160; We express no opinion as to the availability of any equitable or specific remedy upon any breach of any of the agreements as to which we are opining herein, or any of the agreements, documents or obligations referred to therein, or to the successful assertion of any equitable defenses, inasmuch as the availability of such remedies or the success of any equitable defense may be subject to the discretion of a court.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">We also express no opinion herein as to any provision of any agreement (a)&nbsp;which may be deemed to or construed to waive any right of the Company, (b)&nbsp;to the effect that rights and remedies are not exclusive, that every right or remedy is cumulative and may be exercised in addition to or with any other right or remedy and does not preclude recourse to one or more other rights or remedies, (c)&nbsp;relating to the effect of invalidity or unenforceability of any provision of the Common Warrants on the validity or enforceability of any other provision thereof, (d)&nbsp;which is in violation of public policy, including, without limitation, any provision relating to indemnification and contribution with respect to securities law matters, (e)&nbsp;which provides that the terms of the Common Warrants may not be waived or modified except in writing or (f)&nbsp;relating to choice of law or consent to jurisdiction.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">We express no opinion herein as to the laws of any state or jurisdiction other than the General Corporation Law of the State of Delaware.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Based upon and subject to the foregoing, we are of the opinion that:</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1.</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The Shares have been duly authorized for issuance and, when the Shares are issued and paid for in accordance with the terms and conditions of the Underwriting Agreement, the Shares will be validly issued, fully paid and non-assessable.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2.</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The Common Units and the Common Warrants have been duly authorized for issuance and, when the Common Units and the Common Warrants are issued and paid for in accordance with the terms and conditions of the Underwriting Agreement, the Common Units and the Common Warrants will have been duly executed and delivered by the Registrant and will constitute valid and legally binding obligations of the Company.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3.</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The Common Warrant Shares have been duly authorized for issuance and, when issued and paid for in accordance with the provisions of the Common Warrants, including the payment of the exercise price therefor, the Common Warrant Shares will be validly issued, fully paid and non-assessable.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Please note that we are opining only as to the matters expressly set forth herein, and no opinion should be inferred as to any other matters. This opinion is based upon currently existing statutes, rules, regulations and judicial decisions, and we disclaim any obligation to advise you of any change in any of these sources of law or subsequent legal or factual developments which might affect any matters or opinions set forth herein.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement in accordance with the requirements of Item&nbsp;601(b)(5)&nbsp;of Regulation S-K under the Securities Act and to the use of our name therein and in the related Prospectus under the caption &#147;Legal Matters.&#148; In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section&nbsp;7 of the Securities Act or the rules&nbsp;and regulations of the Commission.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Very truly yours,</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">WILMER CUTLER PICKERING   HALE AND DORR LLP</font></p>    </td>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>    </td>
<td width="45%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:45.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ Rosemary G. Reilly</font></p>    </td>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="45%" valign="top" style="padding:0in 0in 0in 0in;width:45.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Rosemary G. Reilly, a   Partner</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>  </table>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<P ALIGN="RIGHT" style="font-family:times;"><FONT SIZE=2><A
NAME="kg49607_exhibit_23.1"> </A>
<A NAME="toc_kg49607_1"> </A>
<BR></FONT><FONT SIZE=2><B>  Exhibit&nbsp;23.1    <BR>    </B></FONT></P>

<P ALIGN="CENTER" style="font-family:times;"><FONT SIZE=2><A
NAME="kg49607_consent_of_independent__kg402328"> </A>
<A NAME="toc_kg49607_2"> </A></FONT> <FONT SIZE=3><B>  Consent of Independent Registered Public Accounting Firm  <BR>  </B></FONT></P>

<P style="font-family:times;"><FONT SIZE=2>We consent to the incorporation by reference in the Registration Statement on Form&nbsp;S-1 filed pursuant to Rule&nbsp;462(b) of the
Securities Act of 1933 of the reference to our firm under the caption "Experts" and to the incorporation by reference of our report dated March&nbsp;15, 2018, with respect to the consolidated
financial statements of Catabasis Pharmaceuticals,&nbsp;Inc. included in its Annual Report (Form&nbsp;10-K) for the year ended December&nbsp;31, 2017, filed with the Securities and Exchange
Commission and incorporated by reference in Amendment No.&nbsp;3 to the Registration Statement (Form&nbsp;S-1 No.&nbsp;333-225410) and related Prospectus of Catabasis
Pharmaceuticals,&nbsp;Inc. for the registration of common units, pre-funded units and shares of common stock issuable upon exercise of warrants included in such common units and pre-funded units. </FONT></P>

<P style="font-family:times;"><FONT SIZE=2>/s/
Ernst&nbsp;&amp; Young&nbsp;LLP </FONT></P>

<P style="font-family:times;"><FONT SIZE=2>Boston,
Massachusetts<BR>
June&nbsp;17, 2018 </FONT></P>

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