<SEC-DOCUMENT>0001104659-20-073505.txt : 20200615
<SEC-HEADER>0001104659-20-073505.hdr.sgml : 20200615
<ACCEPTANCE-DATETIME>20200615202629
ACCESSION NUMBER:		0001104659-20-073505
CONFORMED SUBMISSION TYPE:	S-3MEF
PUBLIC DOCUMENT COUNT:		3
<REFERENCE-462B>333-235399
FILED AS OF DATE:		20200615
DATE AS OF CHANGE:		20200615
EFFECTIVENESS DATE:		20200615

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Celldex Therapeutics, Inc.
		CENTRAL INDEX KEY:			0000744218
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				133191702
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		S-3MEF
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-239199
		FILM NUMBER:		20964703

	BUSINESS ADDRESS:	
		STREET 1:		53 FRONTAGE ROAD
		STREET 2:		SUITE 220
		CITY:			HAMPTON
		STATE:			NJ
		ZIP:			08827
		BUSINESS PHONE:		908-200-7500

	MAIL ADDRESS:	
		STREET 1:		53 FRONTAGE ROAD
		STREET 2:		SUITE 220
		CITY:			HAMPTON
		STATE:			NJ
		ZIP:			08827

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	AVANT IMMUNOTHERAPEUTICS INC
		DATE OF NAME CHANGE:	19980828

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	T CELL SCIENCES INC
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-3MEF
<SEQUENCE>1
<FILENAME>tm2022604-5_s3mef.htm
<DESCRIPTION>S-3MEF
<TEXT>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<!-- Field: Rule-Page --><DIV STYLE="margin-top: 12pt; margin-bottom: 3pt; width: 100%"><DIV STYLE="font-size: 1pt; border-top: Black 2pt solid; border-bottom: Black 1pt solid">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;<FONT STYLE="font-size: 10pt"><B>As
filed with the Securities and Exchange Commission on June 15, 2020</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right"><B>Registration Statement No. 333-</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>UNITED STATES<BR>
SECURITIES AND EXCHANGE COMMISSION<BR>
Washington, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B><BR>
FORM S-3<BR>
REGISTRATION STATEMENT<BR>
UNDER<BR>
THE SECURITIES ACT OF 1933</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><FONT STYLE="font-size: 14pt"><B>CELLDEX
THERAPEUTICS, INC.</B></FONT><B><BR>
</B>(Exact name of Registrant as Specified in Its Charter)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; width: 45%"><FONT STYLE="font-size: 10pt"><B>Delaware</B></FONT></TD>
    <TD STYLE="width: 10%">&nbsp;</TD>
    <TD STYLE="text-align: center; width: 45%"><FONT STYLE="font-size: 10pt"><B>13-3191702</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center"><FONT STYLE="font-size: 10pt">(State of Incorporation)</FONT></TD>
    <TD>&nbsp;</TD>
    <TD STYLE="text-align: center"><FONT STYLE="font-size: 10pt">(I.R.S. Employer<BR>
Identification Number)</FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Perryville III Building, 53 Frontage
Road, Suite 220<BR>
Hampton, New Jersey 08827<BR>
(908) 200-7500<BR>
</B>(Address, including zip code and telephone number, including area code, of Registrant's principal executive offices)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Sam Martin<BR>
Chief Financial Officer<BR>
CELLDEX THERAPEUTICS, INC.<BR>
Perryville III Building, 53 Frontage Road, Suite 220<BR>
Hampton, New Jersey 08827<BR>
(908) 200-7500<BR>
</B>(Name, address, including zip code and telephone number, including area code, of agent for service)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Copies to:</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Anthony O. Pergola, Esq.<BR>
Lowenstein Sandler LLP<BR>
1251 Avenue of the Americas<BR>
New York, New York 10020<BR>
(212) 262-6700</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Approximate date of commencement of proposed
sale to the public:<BR>
From time to time after this registration statement becomes effective, as determined by the registrant.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If the only securities being registered on this Form are being
offered pursuant to dividend or interest reinvestment plans, please check the following box:&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If any of the securities being registered on this Form are to
be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered
only in connection with dividend or interest reinvestment plans, check the following box:&nbsp;<FONT STYLE="font-family: Wingdings">x
</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If this Form is filed to register additional securities for
an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration
statement number of the earlier effective registration statement for the same offering.&nbsp;<FONT STYLE="font-family: Wingdings">x
</FONT>File No. 333-235399</P>




<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If this Form is a post-effective amendment filed pursuant to
Rule 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;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If this Form is a registration statement pursuant to General
Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to
Rule 462(e) under the Securities Act, check the following box.&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If this Form is a post-effective amendment to a registration
statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities
pursuant to Rule 413(b) under the Securities Act, check the following box.&nbsp;<FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">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 &quot;large accelerated filer,&quot; &quot;accelerated filer&quot;, &quot;smaller reporting company,&quot; and &quot;emerging
growth company&quot; in Rule 12b-2 of the Exchange Act.&nbsp;&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD STYLE="width: 18%">&nbsp;</TD>
    <TD STYLE="vertical-align: bottom; width: 1%">&nbsp;</TD>
    <TD STYLE="width: 57%">&nbsp;</TD>
    <TD STYLE="vertical-align: bottom; width: 1%">&nbsp;</TD>
    <TD STYLE="width: 21%">&nbsp;</TD>
    <TD STYLE="vertical-align: bottom; width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD><FONT STYLE="font-size: 10pt">Large&nbsp;accelerated&nbsp;filer</FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Accelerated&nbsp;filer</FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD><FONT STYLE="font-size: 10pt">Non-accelerated filer</FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#120;</FONT></FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Smaller&nbsp;reporting&nbsp;company</FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#120;</FONT></FONT></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt">Emerging growth company</FONT></TD>
    <TD>&nbsp;</TD>
    <TD><FONT STYLE="font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">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 to Section&nbsp;7(a)(2)(B) of the Securities Act.&nbsp;<FONT STYLE="font-family: Wingdings">&#168;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="border-top: Black 1pt solid; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="text-align: center; font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><B>CALCULATION OF REGISTRATION FEE </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD STYLE="border-top: Black 1pt solid; width: 77%">&nbsp;</TD>
    <TD STYLE="border-top: Black 1pt solid; vertical-align: bottom; width: 1%">&nbsp;</TD>
    <TD STYLE="border-top: Black 1pt solid; width: 10%">&nbsp;</TD>
    <TD STYLE="border-top: Black 1pt solid; vertical-align: bottom; width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="border-top: Black 1pt solid; width: 10%">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Title of Each Class&nbsp;of</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Securities to be Registered</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P></TD>
    <TD STYLE="border-top: black 1pt solid; border-left: black 1pt solid">&nbsp;</TD>
    <TD STYLE="white-space: nowrap; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Proposed</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Maximum</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Aggregate</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Offering&nbsp;Price(1)</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P></TD>
    <TD STYLE="border-top: black 1pt solid; border-left: black 1pt solid">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="white-space: nowrap; border-top: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Amount of</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Registration Fee(2)</B>&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-top: black 1pt solid; padding-left: 10pt; text-indent: -10pt"><FONT STYLE="font-size: 10pt">Common Stock, par value $0.001 per share</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-top: black 1pt solid; border-left: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; white-space: nowrap; vertical-align: bottom; text-align: right"><FONT STYLE="font-size: 10pt">&mdash;</FONT></TD>
    <TD STYLE="vertical-align: bottom; border-top: black 1pt solid; border-left: black 1pt solid">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="border-top: black 1pt solid; white-space: nowrap; vertical-align: bottom; text-align: right"><FONT STYLE="font-size: 10pt">&mdash;</FONT></TD></TR>
<TR>
    <TD STYLE="border-top: black 1pt solid; vertical-align: top; padding-left: 10pt"><FONT STYLE="font-size: 10pt">Total</FONT></TD>
    <TD STYLE="border-top: black 1pt solid; border-left: black 1pt solid; vertical-align: bottom">$</TD>
    <TD STYLE="border-top: black 1pt solid; white-space: nowrap; vertical-align: bottom; text-align: right">25,000,000</TD>
    <TD STYLE="border-top: black 1pt solid; border-left: black 1pt solid; vertical-align: bottom">&nbsp;</TD>
    <TD>$</TD>
    <TD STYLE="border-top: black 1pt solid; white-space: nowrap; vertical-align: bottom; text-align: right">3,245</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD COLSPAN="6">
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</TABLE>

<P STYLE="border-bottom: Black 1pt solid; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 4%"><FONT STYLE="font-size: 10pt">(1)</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">The Registrant previously registered an aggregate of $150,000,000.00 of Common Stock, Preferred Stock, Warrants, Depositary Shares and Units on a Registration Statement on Form S-3 (File No.&nbsp;333-235399), as amended, which was declared effective on June 12, 2020 (the &#8220;Related Registration Statement&#8221;), and for which a filing fee of $19,470.00 was previously paid. As of the date hereof, a balance of $125,000,000 of such securities remains to be offered and sold under the Related Registration Statement. In accordance with Rule 462(b) promulgated under the Securities Act, an additional amount of Common Stock, having a proposed maximum aggregate offering price of $25,000,000 is hereby registered. </FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 4%"><FONT STYLE="font-size: 10pt">(2)</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">The registration fee has been calculated pursuant to Rule 457(o) promulgated under the Securities Act of 1933, as amended (the &#8220;Securities Act&#8221;). </FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="border-bottom: Black 1pt solid; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>






<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>This Registration Statement shall become effective upon filing
with the Securities and Exchange Commission in accordance with Rule 462(b) promulgated under the Securities Act. </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>










<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EXPLANATORY NOTE AND INCORPORATION OF
CERTAIN INFORMATION BY REFERENCE </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">This Registration Statement is being filed with the Securities
and Exchange Commission (the &#8220;SEC&#8221;) pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the &#8220;Securities
Act&#8221;). This Registration Statement relates to the public offering of Common Stock of Celldex Therapeutics, Inc. (the &#8220;Registrant&#8221;)
contemplated by the <A HREF="http://www.sec.gov/Archives/edgar/data/744218/000104746919006714/a2240232zs-3.htm" STYLE="-sec-extract: exhibit">Registration Statement on Form S-3, as amended (File No.&nbsp;333-235399), initially filed with the SEC by the</A> <A HREF="http://www.sec.gov/Archives/edgar/data/744218/000104746919006714/a2240232zs-3.htm" STYLE="-sec-extract: exhibit">Registrant on December 6, 2019</A> (as amended on <A HREF="http://www.sec.gov/Archives/edgar/data/744218/000110465920072503/tm2022403-1_s3a.htm" STYLE="-sec-extract: exhibit">June 12, 2020</A>, the &#8220;Related Registration Statement&#8221;), pursuant to
the Securities Act, which was declared effective by the SEC on June 12, 2020. The contents of the Related Registration Statement,
including all amendments and exhibits thereto, are incorporated by reference into this Registration Statement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The Registrant is filing this Registration Statement for the
sole purpose of increasing the aggregate offering price of securities to be offered in the public offering by $25,000,000. The additional
securities that are being registered for issuance and sale are in an amount and at a price that together represent no more than
20% of the maximum aggregate offering price set forth in the Calculation of Registration Fee table contained in the Related Registration
Statement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The required opinion and consents are listed in Part II, Item
16 of this Registration Statement and filed herewith.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Exhibit Index</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="white-space: nowrap; width: 10%"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 1pt solid"><B>Exhibit<BR>
        Number</B></P></TD>
    <TD STYLE="width: 2%">&nbsp;</TD>
    <TD STYLE="white-space: nowrap; width: 88%"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; border-bottom: black 1pt solid"><B>Description of Exhibit</B></P></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="white-space: nowrap; vertical-align: top"><A HREF="tm2022604d5_ex5-1.htm"><FONT STYLE="font-size: 10pt">5.1</FONT></A></TD>
    <TD STYLE="vertical-align: bottom">&nbsp;</TD>
    <TD STYLE="vertical-align: top"><A HREF="tm2022604d5_ex5-1.htm"><FONT STYLE="font-size: 10pt"><U>Opinion of Lowenstein Sandler LLP</U></FONT></A></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="white-space: nowrap; vertical-align: top"><A HREF="tm2022604d5_ex23-1.htm"><FONT STYLE="font-size: 10pt">23.1</FONT></A></TD>
    <TD STYLE="vertical-align: bottom">&nbsp;</TD>
    <TD STYLE="vertical-align: top"><A HREF="tm2022604d5_ex23-1.htm"><FONT STYLE="font-size: 10pt">Consent of Independent Registered Public Accounting Firm </FONT></A></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="white-space: nowrap; vertical-align: top"><A HREF="tm2022604d5_ex5-1.htm"><FONT STYLE="font-size: 10pt">23.2</FONT></A></TD>
    <TD STYLE="vertical-align: bottom">&nbsp;</TD>
    <TD STYLE="vertical-align: top"><A HREF="tm2022604d5_ex5-1.htm"><FONT STYLE="font-size: 10pt">Consent
of Lowenstein Sandler LLP (included in Exhibit 5.1)</FONT></A></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="white-space: nowrap; vertical-align: top"><A HREF="https://www.sec.gov/Archives/edgar/data/744218/000104746919006714/a2240232zs-3.htm#sig" STYLE="-sec-extract: exhibit"><FONT STYLE="font-size: 10pt">24.1(1)</FONT></A></TD>
    <TD STYLE="vertical-align: bottom">&nbsp;</TD>
    <TD STYLE="vertical-align: top"><A HREF="https://www.sec.gov/Archives/edgar/data/744218/000104746919006714/a2240232zs-3.htm#sig" STYLE="-sec-extract: exhibit"><FONT STYLE="font-size: 10pt">Power of Attorney</FONT></A></TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="border-bottom: Black 1pt solid; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 4%"><FONT STYLE="font-size: 10pt">(1)</FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">Previously filed on the signature page to the Registrant&#8217;s Registration Statement on Form S-3, as amended (File No.&nbsp;333-235399), initially filed with the Securities and Exchange Commission on December 6, 2019, as amended on June 12, 2020, and incorporated by reference herein. </FONT></TD></TR>
</TABLE>




<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURES </B></P>




<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Pursuant to the requirements of the Securities Act, the Registrant
has duly caused this Registration Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto duly authorized,
in the City of Hampton, New Jersey, on this 15th day of June, 2020.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt"><B>CELLDEX THERAPEUTICS, INC.</B></FONT></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 52%">&nbsp;</TD>
    <TD STYLE="vertical-align: top; width: 2%"><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD STYLE="vertical-align: top; width: 46%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; border-bottom: black 0.75pt solid">/s/ Anthony S. Marucci</P></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD STYLE="vertical-align: top"><FONT STYLE="font-size: 10pt">Anthony S. Marucci</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 10pt; text-indent: -10pt"><FONT STYLE="font-size: 10pt">President and Chief Executive Officer</FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURES </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Pursuant to the requirements of the Securities Act, this Registration
Statement on Form S-3 has been signed by the following persons in the capacities held on the dates indicated.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; white-space: nowrap; border-bottom: black 1pt solid; padding-bottom: 2pt; text-align: center; width: 45%"><FONT STYLE="font-size: 10pt"><B>Signature</B></FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; border-bottom: black 1pt solid; padding-bottom: 2pt; text-align: center; width: 36%"><FONT STYLE="font-size: 10pt"><B>Title</B></FONT></TD>
    <TD STYLE="padding-top: 2pt; width: 1%; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; border-bottom: black 1pt solid; padding-bottom: 2pt; text-align: center; width: 17%"><FONT STYLE="font-size: 10pt"><B>Date</B></FONT></TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">/s/
Anthony S. Marucci</P></TD>
    <TD ROWSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD ROWSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">President, Chief Executive Officer and Director (<I>Principal Executive Officer</I>)</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Anthony S. Marucci</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">/s/
Sam Martin</P></TD>
    <TD ROWSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD ROWSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Senior Vice President, Chief Financial Officer and Treasurer (<I>Principal Financial and Accounting Officer</I>)</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Sam Martin</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">*</P></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Director, Chair of the Board of Directors</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Karen L. Shoos</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">*</P></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Keith L. Brownlie</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">*</P></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Herbert J. Conrad</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">*</P></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">James J. Marino</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: black 0.75pt solid">*</P></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Director</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">June 15, 2020</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding-top: 2pt; text-align: center; padding-bottom: 2pt"><FONT STYLE="font-size: 10pt">Harry H. Penner, Jr.</FONT></TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD>
    <TD STYLE="padding-top: 2pt; padding-bottom: 2pt">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD STYLE="vertical-align: top; width: 3%"><FONT STYLE="font-size: 10pt">*By:</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid; vertical-align: top; width: 47%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">/s/ Sam Martin</P></TD>
    <TD STYLE="vertical-align: top; width: 50%"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top"><FONT STYLE="font-size: 10pt">Sam Martin</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top"><FONT STYLE="font-size: 10pt">Attorney-in-fact</FONT></TD></TR>
</TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right"></P>

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<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>tm2022604d5_ex5-1.htm
<DESCRIPTION>EXHIBIT 5.1
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
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<BODY STYLE="font: 10pt Times New Roman, Times, Serif">

<P STYLE="text-align: right; margin: 0"><B>Exhibit 5.1 </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">June 15, 2020</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Celldex Therapeutics, Inc.<BR>
Perryville III Building<BR>
53 Frontage Road, Suite 220<BR>
Hampton, NJ 08827</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 10pt; text-indent: -10pt"><B>Re: Shelf Registration Statement
of Celldex Therapeutics, Inc. on Form S-3 </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 10pt; text-indent: -10pt">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Ladies and Gentlemen:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">We have acted as counsel to Celldex Therapeutics, Inc., a Delaware
corporation (the &quot;Company&quot;), in connection with its filing of a registration statement on Form S-3 (the &quot;Registration
Statement&quot;) filed by the Company pursuant to Rule 462(b) promulgated under the Securities Act of 1933, as amended (the &quot;Securities
Act&quot;), relating to an aggregate of $25,000,000 of shares of common stock, par value $0.001 per share, of the Company (the
 &quot;Common Stock&quot;). The Registration Statement incorporates by reference the registration statement on Form S-3 (File No.333-235399),
which was declared effective on June 12, 2020 (the &ldquo;Prior Registration Statement&rdquo;), including the prospectus which
forms a part of the Prior Registration Statement (the &ldquo;Base Prospectus&rdquo;), which provides that it will be supplemented
in the future by one or more prospectus supplements (each a &ldquo;Prospectus Supplement&rdquo;). We have been requested by the
Company to render this opinion in connection with the filing of the Registration Statement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">In rendering our opinion, we have reviewed the Registration
Statement and the exhibits thereto. We have also reviewed such corporate documents and records of the Company, such certificates
of public officials and officers of the Company and such other matters as we have deemed necessary or appropriate for purposes
of this opinion.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">We have assumed that all documents referenced below are the
valid and binding obligations of and enforceable against the parties thereto. We have also assumed the authenticity of all documents
submitted to us as originals, the genuineness of all signatures, the conformity to authentic original documents of all documents
submitted to us as certified, conformed or photostatic copies and the legal capacities of all natural persons.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Based on the foregoing, and subject to the assumptions, limitations
and qualifications set forth herein, we are of the opinion that:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Upon adoption by the Board of Directors of the Company of a
resolution in form and content as required by applicable law authorizing the issuance and sale of Common Stock, and (b) assuming
that the Registration Statement and any required post-effective amendment(s) thereto and any and all Prospectus Supplement(s) required
by applicable laws have become effective under the Securities Act, and (c) assuming that upon the issuance of such Common Stock,
the total number of issued and outstanding shares of Common Stock will not exceed the total number of shares of Common Stock that
the Company is then authorized to issue under the restated certificate of incorporation of the Company, as amended (&quot;Charter&quot;),
then upon issuance and delivery of and payment for such shares in the manner contemplated by the Registration Statement, the Base
Prospectus and the related Prospectus Supplement(s) and by such resolution, such shares of Common Stock being issued by the Company,
will be validly issued, fully paid and non-assessable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The opinions set forth above are subject to the following exceptions,
limitations and qualifications: (i) the effect of bankruptcy, insolvency, reorganization, arrangement, moratorium, fraudulent conveyance,
fraudulent transfer and other similar laws relating to or affecting the rights of creditors; (ii) the effect of general principles
of equity (including, without limitation, concepts of materiality, reasonableness, good faith and fair dealing and the possible
unavailability of specific performance, injunctive relief and other equitable remedies), regardless of whether considered in a
proceeding at law or in equity, (iii) the effect of public policy considerations that may limit the rights of the parties to obtain
further remedies, (iv) we express no opinion with respect to the enforceability of provisions relating to choice of law, choice
of venue, jurisdiction or waivers of jury trial, and (v) we express no opinion with respect to the enforceability of any waiver
of any usury defense.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Our opinion is limited to the federal laws of the United States
and to the Delaware General Corporation law. We express no opinion as to the effect of the law of any other jurisdiction. Our opinion
is rendered as of the date hereof, and we assume no obligation to advise you of changes in law or fact (or the effect thereof on
the opinions expressed herein) that hereafter may come to our attention.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">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 601(b)(5) of Regulation S-K under the Securities
Act and to the use of our name therein and in the related Base Prospectus and any Prospectus Supplement under the caption &quot;Legal
Matters.&quot; In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required
under Section 7 of the Securities Act or the Rules and Regulations of the Commission promulgated thereunder.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Very truly yours,</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">LOWENSTEIN SANDLER LLP</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">/s/ Lowenstein Sandler LLP</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<FILENAME>tm2022604d5_ex23-1.htm
<DESCRIPTION>EXHIBIT 23.1
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<P STYLE="text-align: right; margin-top: 0; margin-bottom: 0"><B>Exhibit 23.1</B></P>

<P STYLE="margin: 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">CONSENT OF INDEPENDENT REGISTERED PUBLIC
ACCOUNTING FIRM</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">We hereby consent to the incorporation by reference in this
Registration Statement on Form&nbsp;S-3 of our report dated March 26, 2020 relating to the financial statements, which is incorporated
by reference in Amendment No. 1 to the Registration Statement on Form S-3 (No. 333-235399) of Celldex Therapeutics, Inc. We also
consent to the reference to us under the heading &ldquo;Experts&rdquo; in Amendment No. 1 to the Registration Statement on Form
S-3 (No. 333-235399) incorporated by reference in this Registration Statement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">/s/ PricewaterhouseCoopers LLP</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Boston, MA<BR>
June 15, 2020</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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