<SEC-DOCUMENT>0001193125-26-236834.txt : 20260522
<SEC-HEADER>0001193125-26-236834.hdr.sgml : 20260522
<ACCEPTANCE-DATETIME>20260522160416
ACCESSION NUMBER:		0001193125-26-236834
CONFORMED SUBMISSION TYPE:	DEFA14A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20260522
DATE AS OF CHANGE:		20260522

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Sensei Biotherapeutics, Inc.
		CENTRAL INDEX KEY:			0001829802
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		DEFA14A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39980
		FILM NUMBER:		261013580

	BUSINESS ADDRESS:	
		STREET 1:		1405 RESEARCH BLVD, SUITE 125
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850
		BUSINESS PHONE:		(240) 243-8000

	MAIL ADDRESS:	
		STREET 1:		1405 RESEARCH BLVD, SUITE 125
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850
</SEC-HEADER>
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<TYPE>DEFA14A
<SEQUENCE>1
<FILENAME>d151872ddefa14a.htm
<DESCRIPTION>DEFA14A
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<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES
AND EXCHANGE COMMISSION </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center><DIV STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</DIV></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SCHEDULE 14A </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Rule <FONT
STYLE="white-space:nowrap">14a-101)</FONT> </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Proxy Statement Pursuant to Section&nbsp;14(a) of the </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Securities Exchange Act of 1934 </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center><DIV STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</DIV></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Filed by Registrant&#8194;&#9746; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Filed by Party other than
Registrant&#8194;&#9744; </P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box: </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9744;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Preliminary Proxy Statement </P></TD></TR></TABLE>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left"><B></B>&#9744;<B></B><B></B></TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left"><B>Confidential, for Use of the Commission Only (as permitted by Rule
<FONT STYLE="white-space:nowrap">14a-6(e)(2))</FONT> </B></P></TD></TR></TABLE> <P STYLE="font-size:12pt;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">&#9744;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Definitive Proxy Statement </P></TD></TR></TABLE>
<P STYLE="font-size:12pt;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">&#9746;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Definitive Additional Materials </P></TD></TR></TABLE>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Soliciting Materials Pursuant to <FONT STYLE="white-space:nowrap">&#167;240.14a-12</FONT>
</P></TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>Sensei Biotherapeutics, Inc. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Name of Registrant as Specified In Its Charter) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Name of Person(s) Filing Proxy Statement, if other than the Registrant) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Payment of Filing Fee (Check the appropriate box): </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9746;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">No fee required </P></TD></TR></TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Fee paid previously with preliminary materials </P></TD></TR></TABLE>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9744;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules
<FONT STYLE="white-space:nowrap">14a-6(i)(1)</FONT> and <FONT STYLE="white-space:nowrap">0-11</FONT> </P></TD></TR></TABLE>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SENSEI BIOTHERAPEUTICS, INC. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>1405 Research Boulevard, Suite 125 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Rockville, Maryland 20850 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PROXY STATEMENT SUPPLEMENT </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Dated: May&nbsp;22, 2026 </B></P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>The following
disclosures in this proxy supplement (the &#8220;Supplement&#8221;) supplement, and should be read in conjunction with, the disclosures contained in the definitive proxy statement (the &#8220;Definitive Proxy Statement&#8221;) of Sensei
Biotherapeutics, Inc. (the &#8220;Company&#8221;), filed with the Securities and Exchange Commission (the &#8220;SEC&#8221;) on April&nbsp;27, 2026, which in turn should be read in its entirety. The purpose of the Supplement is to provide an update
regarding the expected reconstitution of the board of directors of the Company (the &#8220;Board&#8221;) if the Required Company Stockholder Matters (as defined in the Definitive Proxy Statement) are approved. Due to personal reasons, Karen Vousden,
Ph.D. has requested that her appointment be delayed until later in 2026; the Board intends to consider appointing her in the third or fourth quarter of 2026. If the Required Company Stockholder Matters are approved, the Board intends to appoint Bob
Holmen as chair of the Nominating and Corporate Governance Committee effective June&nbsp;12, 2026, when the other board appointments would become effective. The Board has also approved a Board size of five directors as of that date. To the extent
the information set forth herein differs from or updates information contained in the Definitive Proxy Statement, the information set forth herein shall supersede or supplement the information in the Definitive Proxy Statement. All other information
in the Definitive Proxy Statement remains unchanged. Terms used herein, unless otherwise defined, have the meanings set forth in the Definitive Proxy Statement. </I></P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>The Board of Directors&#8217; recommendation with respect to each proposal set forth in the Definitive Proxy Statement remains unchanged. </I></P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>Additional Information and Where You Can Find It </U></B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The Company has filed with the SEC the Definitive Proxy Statement and proxy cards with respect to the solicitation of proxies for its 2026 Annual Meeting of
Stockholders to be held on June&nbsp;10, 2026 at 11:00 a.m. Eastern Daylight Time through a live webcast at www.proxydocs.com/SNSE (the &#8220;Annual Meeting&#8221;). STOCKHOLDERS OF THE COMPANY ARE URGED TO READ THE DEFINITIVE PROXY STATEMENT, THIS
SUPPLEMENT AND ANY OTHER RELEVANT DOCUMENTS THAT THE COMPANY HAS FILED OR WILL FILE WITH THE SEC BECAUSE THEY CONTAIN OR WILL CONTAIN IMPORTANT INFORMATION ABOUT THE COMPANY AND THE MATTERS TO BE VOTED ON AT THE ANNUAL MEETING. You may obtain these
documents free of charge on the SEC&#8217;s website at www.sec.gov and on the Company&#8217;s website at www.senseibio.com. Stockholders may also obtain copies of the Definitive Proxy Statement and this Supplement, without charge, by contacting the
Company&#8217;s Corporate Secretary at 1405 Research Boulevard, Suite 125, Rockville, Maryland 20850. The record date for the Annual Meeting is April&nbsp;13, 2026. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Pursuant to SEC rules, the Company has elected to provide access to its proxy materials on the Internet instead of mailing printed copies of its proxy
materials to all of its stockholders. Accordingly, the Company has sent a separate Notice of Internet Availability of Proxy Materials (the &#8220;Notice&#8221;) to its stockholders of record as of the record date. All stockholders of record will
have the ability to access the proxy materials and the Company&#8217;s 2025 Annual Report on the website referred to in the Notice or request to receive a printed copy of the proxy materials and 2025 Annual Report. Instructions on how to access the
proxy materials and the 2025 Annual Report on the Internet or request a printed copy may be found in the Notice. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">No proxy cards are being furnished by
this communication. Stockholders may vote their shares by using the directions on the Notice, or, if they elected to receive printed proxy materials by mail, on their proxy card, to vote by one of the following methods: (1)&nbsp;over the Internet
before the Annual Meeting at www.proxypush.com/SNSE and during the Annual Meeting at www.proxydocs.com/SNSE, (2)&nbsp;by telephone by calling the toll-free number (866) <FONT STYLE="white-space:nowrap">284-5317,</FONT> or (3)&nbsp;if they elected to
receive printed proxy materials by mail, by marking, dating, and signing their proxy card and returning it in the accompanying postage-paid envelope. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>Participant Information </U></B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The Company and its
directors, executive officers and certain of its employees are deemed to be &#8220;participants&#8221; (as defined in Section&nbsp;14(a) of the Securities Exchange Act of 1934, as amended) in the solicitation of proxies from the Company&#8217;s
stockholders in connection with the matters to be considered at the Annual Meeting. Information about the compensation of the Company&#8217;s named executive officers and <FONT STYLE="white-space:nowrap">non-employee</FONT> directors is set forth in
the sections titled &#8220;Executive Compensation&#8221; and &#8220;Director Compensation&#8221; in the Definitive Proxy Statement. Information regarding the participants&#8217; holdings of the Company&#8217;s securities can be found in the section
titled &#8220;Security Ownership of Certain Beneficial Owners and Management&#8221; in the Definitive Proxy Statement. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>Forward-Looking Statements
</U></B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">This Supplement contains forward-looking statements within the meaning of Section&nbsp;27A of the Securities Act of 1933, as amended, and
Section&nbsp;21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements include, but are not limited to, statements regarding: (i)&nbsp;the expected reconstitution of the Board if the Required Company Stockholder
Matters are approved; (ii)&nbsp;the anticipated timing and effectiveness of Board appointments, including the appointment of Bob Holmen as chair of the Nominating and Corporate Governance Committee; (iii)&nbsp;the Board&#8217;s intention to consider
the appointment of Karen Vousden, Ph.D. in the third or fourth quarter of 2026; (iv) the anticipated size of the Board; and (v)&nbsp;other statements that are not historical facts. Forward-looking statements are generally identified by the use of
words such as &#8220;anticipate,&#8221; &#8220;believe,&#8221; &#8220;could,&#8221; &#8220;estimate,&#8221; &#8220;expect,&#8221; &#8220;intend,&#8221; &#8220;may,&#8221; &#8220;plan,&#8221; &#8220;potential,&#8221; &#8220;predict,&#8221;
&#8220;project,&#8221; &#8220;should,&#8221; &#8220;will,&#8221; &#8220;would,&#8221; and similar expressions. These forward-looking statements are based on the Company&#8217;s current expectations and assumptions and are subject to risks and
uncertainties that could cause actual results to differ materially from those anticipated. Factors that could cause or contribute to such differences include, but are not limited to: (i)&nbsp;the receipt of stockholder approval of the Required
Company Stockholder Matters; (ii)&nbsp;changes in the expected timing or composition of the reconstituted Board; and (iii)&nbsp;other risks and uncertainties described in the Company&#8217;s filings with the SEC, including the Definitive Proxy
Statement. The Company undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by applicable law. </P>
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