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<SEC-DOCUMENT>0001104659-08-018093.txt : 20080317
<SEC-HEADER>0001104659-08-018093.hdr.sgml : 20080317
<ACCEPTANCE-DATETIME>20080317171719
ACCESSION NUMBER:		0001104659-08-018093
CONFORMED SUBMISSION TYPE:	SC 13D
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20080317
DATE AS OF CHANGE:		20080317

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AVANT IMMUNOTHERAPEUTICS 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:		SC 13D
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-37761
		FILM NUMBER:		08693988

	BUSINESS ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			02494
		BUSINESS PHONE:		7814330771

	MAIL ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			021942725

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	T CELL SCIENCES INC
		DATE OF NAME CHANGE:	19920703

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MEDAREX INC
		CENTRAL INDEX KEY:			0000874255
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731]
		IRS NUMBER:				222822175
		STATE OF INCORPORATION:			NJ
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D

	BUSINESS ADDRESS:	
		STREET 1:		707 STATE ROAD 206
		CITY:			PRINCETON
		STATE:			NJ
		ZIP:			08540
		BUSINESS PHONE:		9087136001

	MAIL ADDRESS:	
		STREET 1:		707 STATE ROAD 206
		CITY:			PRINCETON
		STATE:			NJ
		ZIP:			08540
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13D
<SEQUENCE>1
<FILENAME>a08-8339_1sc13d.htm
<DESCRIPTION>SC 13D
<TEXT>

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  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">UNITED STATES</font></b></p>
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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>
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  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
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  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">SECURITIES AND EXCHANGE COMMISSION</font></b></p>
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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>
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 </tr>
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  <td width="54%" valign="top" style="padding:0in .7pt .7pt .7pt;width:54.02%;">
  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Washington, D.C. 20549</font></b></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in .7pt .7pt .7pt;width:22.98%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="23%" valign="top" style="padding:0in .7pt .7pt .7pt;width:23.0%;">
  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="54%" valign="top" style="padding:0in .7pt .7pt .7pt;width:54.02%;">
  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in .7pt .7pt .7pt;width:22.98%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr height="19" style="height:.2in;">
  <td width="23%" height="19" valign="top" style="height:.2in;padding:0in .7pt .7pt .7pt;width:23.0%;">
  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="54%" height="19" valign="top" style="height:.2in;padding:0in .7pt .7pt .7pt;width:54.02%;">
  <p align="center" style="margin:0in 0in .0001pt 10.0pt;text-align:center;text-indent:-10.0pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">SCHEDULE 13D</font></b></p>
  </td>
  <td width="22%" height="19" valign="bottom" style="height:.2in;padding:0in .7pt .7pt .7pt;width:22.98%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
</table>

<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;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Under the Securities Exchange Act
of 1934 <br>
(Amendment No.&#160;&#160;&#160;&#160; )*</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<div style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in;">

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">AVANT
Immunotherapeutics, Inc.</font></b></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name of Issuer)</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<div style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in;">

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Common
Stock, par value $0.001 per share</font></b></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Title of Class of
Securities)</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<div style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in;">

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">053491205</font></b></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(CUSIP Number)</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in;">

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Ursula
B. Bartels</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Senior
Vice President, General Counsel and Secretary</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Medarex,
Inc.</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">707
State Road</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Princeton,
NJ 08540</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(609)
430-2880<br><br></font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;font-weight:bold;">With a Copy to:</font></i></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Nancy
H. Wojtas</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Cooley
Godward Kronish LLP</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Five
Palo Alto Square</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">3000
El Camino Real</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Palo
Alto, CA 94306</font></b></p>

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(650)
843-5000</font></b></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name, Address and
Telephone Number of Person<br>
Authorized to Receive Notices and Communications)</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<div style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in;">

<p align="center" style="border:none;margin:0in 0in .0001pt;padding:0in;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">March
7, 2008</font></b></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Date of Event Which
Requires Filing of this Statement)<br><br></font></p>

<p style="margin:0in .5in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">If the filing person has previously filed a statement
on Schedule 13G to report the acquisition that is the subject of this Schedule
13D, and is filing this schedule because of &#167;&#167;240.13d-1(e), 240.13d-1(f) or
240.13d-1(g), check the following box. </font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>

<p style="margin:5.0pt .5in;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Note</font></b><font size="2" style="font-size:10.0pt;">: Schedules filed in paper format shall include a signed original and
five copies of the schedule, including all exhibits. See Rule 13d-7 for other
parties to whom copies are to be sent. </font></p>

<p style="margin:5.0pt .5in;"><sup><font size="2" face="Times New Roman" style="font-size:10.0pt;">*</font></sup><font size="2" style="font-size:10.0pt;"> The remainder of this cover page shall
be filled out for a reporting person's initial filing on this form with respect
to the subject class of securities, and for any subsequent amendment containing
information which would alter disclosures provided in a prior cover page. </font></p>

<p style="margin:0in .5in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The information required on the remainder of this
cover page shall not be deemed to be &quot;filed&quot; for the purpose of
Section 18 of the Securities Exchange Act of 1934 (&quot;Act&quot;) or
otherwise subject to the liabilities of that section of the Act but shall be
subject to all other provisions of the Act (however, see the Notes).</font></p>

<p style="margin:0in .5in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<div style="font-family:Times New Roman;">

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div align="center">

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="100%" colspan="6" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">CUSIP No.&nbsp; </font><font size="2" style="font-size:10.0pt;">&nbsp;583916101</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Names of Reporting Persons<br>
  Medarex, Inc.</font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">I.R.S. Employer Identification Number: 22-2822175</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2.</font></p>
  </td>
  <td width="91%" colspan="4" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check the Appropriate Box
  if a Member of a Group (See Instructions)</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="8%" colspan="3" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.36%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(a)</font></p>
  </td>
  <td width="82%" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:82.74%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="8%" colspan="3" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.36%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(b)</font></p>
  </td>
  <td width="82%" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:82.74%;">
  <p style="margin:4.0pt 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font><font size="2" face="Wingdings" style="font-size:10.0pt;">x</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">SEC Use Only </font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Source of Funds (See
  Instructions)<br>
  OO</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check if Disclosure of Legal Proceedings Is
  Required Pursuant to Items 2(d) or 2(e)&nbsp;
  </font><font size="2" style="font-size:10.0pt;">&nbsp;&nbsp;&nbsp;</font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">6.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Citizenship or Place of Organization<br>
  New Jersey</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="12%" colspan="3" rowspan="7" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:12.04%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Number of<br>
  Shares<br>
  Beneficially<br>
  Owned by<br>
  Each<br>
  Reporting<br>
  Person With</font></p>
  </td>
  <td width="4%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:4.46%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">7.</font></p>
  </td>
  <td width="83%" colspan="2" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:83.5%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Sole Voting Power <br>
  5,312,539</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="87%" colspan="3" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:87.96%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="4%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:4.46%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">8.</font></p>
  </td>
  <td width="83%" colspan="2" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:83.5%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Shared Voting Power</font><font size="2" style="font-size:10.0pt;">  <br>
  0</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="87%" colspan="3" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:87.96%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="4%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:4.46%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">9.</font></p>
  </td>
  <td width="83%" colspan="2" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:83.5%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Sole Dispositive Power</font><font size="2" style="font-size:10.0pt;">  <br>
  5,312,539</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="87%" colspan="3" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:87.96%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr style="page-break-inside:avoid;">
  <td width="4%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:4.46%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">10.</font></p>
  </td>
  <td width="83%" colspan="2" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:83.5%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Shared Dispositive Power</font><font size="2" style="font-size:10.0pt;">  <br>
  0</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">11.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Aggregate Amount
  Beneficially Owned by Each Reporting Person</font><font size="2" style="font-size:10.0pt;">  <br>
  5,312,539</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">12.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check if the Aggregate Amount
  in Row (11) Excludes Certain Shares (See Instructions)</font><font size="2" style="font-size:10.0pt;">&nbsp;&nbsp;
  </font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">13.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Percent of Class
  Represented by Amount in Row (11)</font><font size="2" style="font-size:10.0pt;">  <br>
  35.6%</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="6" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="3%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:3.32%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="5%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:5.58%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">14.</font></p>
  </td>
  <td width="91%" colspan="4" style="border:none;border-bottom:solid windowtext 1.0pt;padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:4.0pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Type of Reporting Person
  (See Instructions)</font><font size="2" style="font-size:10.0pt;"><br>
  CO</font></p>
  </td>
 </tr>
 <tr height="0">
  <td width="25" style="border:none;"></td>
  <td width="42" style="border:none;"></td>
  <td width="23" style="border:none;"></td>
  <td width="33" style="border:none;"></td>
  <td width="6" style="border:none;"></td>
  <td width="619" style="border:none;"></td>
 </tr>
</table>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<br clear="all" style="page-break-before:always;">


<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 1.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Security and Issuer</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This Statement on
  Schedule 13D relates to the Common Stock, par value $0.001 per share (the
  &#147;Common Stock&#148;), of AVANT Immunotherapeutics, Inc., a Delaware corporation
  (&#147;AVANT&#148;). AVANT&#146;s principal executive offices are located at 119 Fourth Avenue,
  Needham, Massachusetts 02494.</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 2.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Identity and Background</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This statement is filed
  by Medarex, Inc., a New Jersey corporation (&#147;Medarex&#148; or the &#147;Reporting
  Person&#148;). Medarex is a biopharmaceutical company focused on the discovery,
  development and commercialization of fully human antibody-based therapeutic
  product candidates for the treatment of a wide range of diseases, including
  cancer, inflammation, autoimmune disorders and other life-threatening and
  debilitating diseases. Medarex&#146;s principal place of business and executive
  offices are located at 707 State Road, Princeton, New Jersey 08540.</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;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The name, business
  address, and principal occupation of each executive officer and director of
  the Reporting Person is as set forth on <u>Appendix A</u> attached hereto.
  Each executive officer and director of the Reporting Person is a United
  States citizen.</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;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">During the past five
  years, neither Medarex nor, to Medarex&#146;s knowledge, any of the directors and
  executive officers of Medarex, (1) has been convicted in a criminal
  proceeding (excluding traffic violations and similar misdemeanors) or (2) was
  a party to a civil proceeding of a judicial or administrative body of
  competent jurisdiction and as a result of such proceeding were or are subject
  to a judgment, decree or final order enjoining future violations of, or
  prohibited or mandating activities subject to, U.S. federal or state
  securities laws or finding any violations with respect to such laws.&nbsp; </font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 3.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Source and Amount of Funds or Other
  Consideration</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">On March 7, 2008, AVANT
  announced the closing of a business combination transaction (the &#147;Merger&#148;)
  pursuant to a certain Agreement and Plan of Merger, dated October 19, 2007
  (the &#147;Merger Agreement&#148;) by and among AVANT, Callisto Merger Corporation
  (&#147;Callisto&#148;), a wholly-owned subsidiary of AVANT, and Celldex Therapeutics,
  Inc. (&#147;Celldex&#148;).&nbsp; Pursuant to the
  terms of the Merger Agreement, Callisto merged with and into Celldex, with
  Celldex as the surviving company and a wholly-owned subsidiary of AVANT.&nbsp; Medarex owned approximately 60% of Celldex
  prior to the Merger and, as a result of the Merger and pursuant to the terms
  of the Merger Agreement, Medarex received approximately 4.9 shares of AVANT&#146;s
  Common Stock in exchange for each share it held in Celldex prior to the
  Merger, subject to adjustment to account for a 1-for-12 reverse stock split
  approved by AVANT&#146;S board of directors on the closing date of the Merger
  Agreement.&nbsp; As a result of the Merger
  and pursuant to the terms of the Merger Agreement, Medarex was issued
  4,960,848 shares of AVANT Common Stock in exchange for the shares it
  previously held in Celldex and 351,691 shares of AVANT Common Stock in
  settlement&nbsp;of a prior dispute between Medarex and Celldex which
  obligation was assumed by AVANT in the Merger.</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 4.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Purpose of Transaction</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The shares of Common
  Stock owned by Medarex were acquired as the result of the Merger described in
  Item 3 above.&nbsp; Medarex holds such
  shares of Common Stock for investment purposes.</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">As part of the terms of
  the Merger Agreement, AVANT assumed Celldex&#146;s obligations with respect to
  each outstanding option to purchase shares of Celldex common stock under
  Celldex&#146;s 2005 Equity Incentive Plan.&nbsp;
  Prior to the closing of the Merger, Charles Schaller, Chairman of the
  Board of Directors of Celldex and member of the Board of Directors of
  Medarex, held an option to purchase shares of Celldex common stock which was
  assumed by AVANT and is exercisable for up to 14,882 shares of AVANT Common
  Stock (on a post-split basis).&nbsp; </font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Except as described
  above, the Reporting Person does not have any plans or proposals which relate
  to or would result in:</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1) the acquisition by
  any person of additional securities of AVANT or the disposition of additional
  securities of AVANT;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2) an extraordinary corporate
  transaction such as a merger, reorganization or liquidation of AVANT, </font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">3</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">involving AVANT or any of its subsidiaries;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3) the sale or
  transfer of a material amount of assets of AVANT or any of its subsidiaries;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(4) any change in the
  present board of directors or management of AVANT;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5) any material change
  in AVANT&#146;s present capitalization or dividend policy;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(6) any other material
  change in AVANT&#146;s business or corporate structure;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(7) changes in AVANT&#146;s
  charter, bylaws or instruments corresponding thereto or other actions which
  may impede the acquisition of control of AVANT by any person;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(8) causing a class of
  securities of AVANT to be delisted from a national securities exchange or to
  cease to be authorized to be quoted in an inter-dealer quotation system of a
  registered national securities association;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(9) a class of
  securities of AVANT becoming eligible for termination of registration
  pursuant to Section 12(g)(4) of the Act; or</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(10) any action similar
  to any of those enumerated above.</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Although there is no
  present intention to do so, the Reporting Person and/or any person named on <u>Appendix
  A</u> attached hereto may decide to make additional purchases or dispose of
  its Common Stock in the future either in the open market or in private
  transactions, subject to its or their evaluation of the AVANT&#146;s business,
  prospects and financial condition, the market for the Common Stock, other
  opportunities available to the Reporting Person or any person named on <u>Appendix
  A</u> attached hereto, prospects for the respective business&#146; of the
  Reporting Person or any person named on <u>Appendix A</u> attached hereto,
  general economic conditions, money and stock market conditions and other
  future developments.</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  <p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Depending upon the
  results of the reviews and the other factors mentioned above, the Reporting
  Person or any person named on <u>Appendix A</u> attached hereto, at any time,
  may decide to change its or his intention with respect to the acquisition
  and/or retention of shares of Common Stock, including, without limitation, a
  determination to increase, decrease or entirely dispose of its or his
  holdings of Common Stock, although neither the Reporting Person nor, to the
  knowledge of the Reporting Person, any of the persons named on <u>Appendix A</u>
  attached hereto has any current intention to do so.</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 5.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Interest in Securities of the Issuer</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt .55in;text-indent:-.55in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(a) &#150; (b) &nbsp;&nbsp;&nbsp;&nbsp;Set
  forth below is information concerning the beneficial ownership of AVANT
  Common Stock, as determined in accordance with Rule 13d-3(d) of the
  Securities and Exchange Act, by the Reporting Person and each other person
  for which disclosure is required under this Schedule 13D pursuant to General
  Instruction C.</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="53%" style="border-collapse:collapse;margin-left:.6in;width:53.34%;">
 <tr>
  <td width="70%" valign="bottom" style="padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="4%" valign="bottom" style="padding:0in 0in 0in 0in;width:4.68%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="22%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Medarex,&nbsp;Inc.</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Beneficial Ownership</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;border:none;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5,312,539</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" style="padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="4%" valign="bottom" style="padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Percentage of Class</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">35.6</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" style="padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="4%" valign="bottom" style="padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Sole Voting Power</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5,312,539</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" style="padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="4%" valign="bottom" style="padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Shared Voting Power</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">-0-</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <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 align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">4</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<br clear="all" style="page-break-before:always;">


<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="53%" style="border-collapse:collapse;margin-left:.6in;width:53.34%;">
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Sole Dispositive Power</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5,312,539</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" style="padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="4%" valign="bottom" style="padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" style="padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="70%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:70.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Shared Dispositive Power</font></b></p>
  </td>
  <td width="4%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:4.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="22%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:22.5%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">-0-</font></p>
  </td>
  <td width="1%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:1.88%;">
  <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;"><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;">Except as noted in the above table, none of the individuals listed on <u>Appendix
A</u> hereto beneficially own any securities of AVANT.</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;">Medarex may be deemed to have sole voting power and the sole power to
dispose of the Common Stock acquired by Medarex in the Merger. To the extent
that each of Medarex&#146;s directors may be deemed to share the power to vote (and
direct the vote of) or dispose of (or direct the disposition of) the shares of
Common Stock owned of record by Medarex, each such director disclaims
beneficial ownership of the shares of Common Stock owned by Medarex.</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;">(c)&#160; Except as otherwise
described in this Schedule 13D, there have been no transactions in the Common
Stock of AVANT by the Reporting Person or any of its executive officers or
directors in the sixty days prior to the date of filing this Schedule 13D.</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;">(d)&#160; Not applicable.</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;">(e)&#160; Not applicable.</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 6.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Contracts, Arrangements, Understandings or
  Relationships with Respect to Securities of the Issuer</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="2" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;">Lock-up Agreements</font></i></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;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Under the terms of the
  Merger Agreement, Medarex and each continuing executive officer and director
  of AVANT and Celldex were required to deliver to AVANT a &#147;lock-up&#148; agreement
  (each, a &#147;Lock-up Agreement&#148;). Pursuant to Medarex&#146;s Lock-up Agreement, a
  portion of the shares of Common Stock issued to Medarex in the Merger may not
  be, directly or indirectly, sold for a period of three months following
  completion of the Merger and the balance of the shares may not be, directly
  or indirectly, sold for a period of twelve months following the closing of
  the Merger. Mr. Schaller may not, directly or indirectly, sell any shares of
  Common Stock, including any shares of Common Stock issuable upon exercise of
  his option, during the six month period following the closing of the
  Merger.&nbsp; The description contained in
  this Schedule 13D of each Lock-up Agreement is qualified in its entirety by
  reference to the full text of each Lock-up Agreement, a copy of which is
  incorporated by reference in this Schedule 13D &#151; See Exhibits 2 and 3.</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;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;">Board Representative</font></i></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;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the Merger
  Agreement, Mr. Schaller was designated as a member of AVANT&#146;s board of
  directors simultaneous with the closing of the Merger.&nbsp; Mr. Schaller is also a member of the board
  of directors of Medarex.</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" valign="top" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:8.9%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 7.</font></b></p>
  </td>
  <td width="91%" style="padding:3.0pt 3.0pt 3.0pt 3.0pt;width:91.1%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Material to be Filed as Exhibits</font></b></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="8%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:8.64%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit<br>
  Number</font></b></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.22%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="89%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:89.14%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit&nbsp;Description</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="8%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:8.64%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1&#134;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="89%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:89.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Agreement
  and Plan of Merger dated as of October&nbsp;19, 2007 by and among AVANT
  Immunotherapeutics,&nbsp;Inc., Callisto Merger Corporation and Celldex
  Therapeutics,&nbsp;Inc.</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.64%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.64%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Lock-up
  Agreement between Medarex,&nbsp;Inc. and AVANT Immunotherapeutics,&nbsp;Inc.</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">5</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.64%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Lock-up
  Agreement between Charles R. Schaller and AVANT Immunotherapeutics,&nbsp;Inc.</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="1" width="25%" noshade color="black" align="left"></div>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&#134;Incorporated by reference to Annex A of the Registration Statement on
Form S-4 (File No. 333-148291), filed by AVANT Immunotherapeutics, Inc. with
the SEC on December 12, 2007.</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">6</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Signature</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.6in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">After reasonable inquiry and to the best of my
knowledge and belief, I certify that the information set forth in this statement
is true, complete and correct.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="45%" valign="top" style="padding:0in 0in 0in 0in;width:45.84%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="54%" valign="top" style="padding:0in 0in 0in 0in;width:54.16%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">MEDAREX,
  INC.</font></b></p>
  </td>
 </tr>
 <tr>
  <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;">&nbsp;</font></p>
  </td>
  <td width="54%" valign="top" style="padding:0in 0in 0in 0in;width:54.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <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;">Date:
  March&nbsp;17, 2008</font></p>
  </td>
  <td width="54%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:54.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;/s/ Howard H. Pien</font></p>
  </td>
 </tr>
 <tr>
  <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:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="54%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:54.16%;">
  <p style="margin:0in 0in .0001pt 20.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Howard H. Pien,</font></p>
  </td>
 </tr>
 <tr>
  <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:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="54%" valign="top" style="padding:0in 0in 0in 0in;width:54.16%;">
  <p style="margin:0in 0in .0001pt 20.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">President and Chief Executive Officer</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">7</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">APPENDIX A</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">LIST OF EXECUTIVE OFFICERS AND DIRECTORS OF THE
REPORTING PERSON</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Directors
of Medarex,&nbsp;Inc.</font></b></p>

<p style="margin:0in 0in .0001pt 29.7pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Patricia
  M. Danzon</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540</font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Celia Moh Professor, Health Care Systems, Insurance and Risk
  Management at the Wharton School of the University of Pennsylvania.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Robert
  C. Dinerstein</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Mr.&nbsp;Dinerstein has served as the Global Co-Chair and New
  York Chair of the Financial Institutions Practice at Greenberg Traurig, LLP,
  an international law firm, where he focuses on banking and securities
  regulation, new product development and international capital markets issues.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Abhijeet
  J. Lele</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Managing Member of EGS Healthcare Capital Partners, a venture
  capital firm that focuses on investments in biopharmaceutical, specialty
  pharmaceutical and medical device companies.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Irwin
  Lerner</font></b><font size="2" style="font-size:10.0pt;"> (Chairman) </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Independent consultant.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Marc
  Rubin</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: President and Chief Executive Officer of Titan
  Pharmaceutical,&nbsp;Inc., a biopharmaceutical company publicly traded on the
  American Stock Exchange.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Ronald
  J. Saldarini</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Associate at Naimark&nbsp;&amp; Associates, a healthcare
  consulting firm.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Charles
  R. Schaller</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Chemical industry management consultant.</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Julius
  A. Vida</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Address:
  707 State Road, Princeton, NJ 08540 </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Principal
  Employment: Pharmaceutical consultant with VIDA International Pharmaceutical
  Consultants.</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">8</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Executive Officers of Medarex,&nbsp;Inc.&#134;</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Ursula
  B. Bartels</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President, General Counsel and Secretary</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Nils
  Lonberg</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President and Scientific Director</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">W.
  Bradford Middlekauff</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President, Strategic Planning</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Geoffrey
  M. Nichol</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President, Product Development</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Ronald
  A. Pepin</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President, Business Development</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Howard
  H. Pien&#135;</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">President
  and Chief Executive Officer</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Christian
  S. Schade</font></b><font size="2" style="font-size:10.0pt;">  </font></p>
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior
  Vice President, Finance and Administration, and Chief Financial Officer</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="1" width="25%" noshade color="black" align="left"></div>

<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&#134; </font></b><font size="2" style="font-size:10.0pt;">The principal employment of each executive officer
is with Medarex,&nbsp;Inc.&#160; The business
address of each executive officer with Medarex is: Medarex,&nbsp;Inc. 707 State
Road, Princeton, NJ 08540.</font></p>

<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&#135;&#160; </font></b><font size="2" style="font-size:10.0pt;">Mr.&nbsp;Pien is also a
member of the Board of Directors of Medarex,&nbsp;Inc.</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><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" style="font-size:10.0pt;">9</font></p>

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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;2</font></b></p>

<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<h1 align="center" style="font-weight:normal;margin:0in 0in .0001pt;text-align:center;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">October&nbsp;19, 2007</font></h1>

<h1 align="center" style="font-weight:normal;margin:0in 0in .0001pt;text-align:center;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></h1>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Avant Immunotherapeutics,&nbsp;Inc.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">119 Fourth Avenue</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Needham, MA 02194</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<h1 style="font-weight:normal;margin:0in .5in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Re:&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <u>Lockup
Agreement (the &#147;<b>Agreement</b>&#148;)</u></font></h1>

<h1 style="font-weight:normal;margin:0in .5in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></h1>

<h1 style="font-weight:normal;margin:0in .5in .0001pt;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Ladies and Gentlemen:</font></h1>

<h1 style="font-weight:normal;margin:0in .5in .0001pt;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></h1>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The undersigned
stockholder of Celldex Therapeutics,&nbsp;Inc., Delaware corporation (&#147;<b>Celldex</b>&#148;), understands that Avant Immunotherapeutics,&nbsp;Inc.,
a Delaware corporation (&#147;<b>Avant</b>&#148;), and
Callisto Merger Corporation, a Delaware corporation and a wholly-owned
subsidiary of Avant (the &#147;<b>Merger Sub</b>&#148;),
have entered into an Agreement and Plan of Merger, dated as of October&nbsp;19,
2007 (as the same may be amended and restated from time to time, the &#147;<b>Merger Agreement</b>&#148;), with Celldex, pursuant to which the
Merger Sub will merge with and into Celldex, and, in connection therewith,
holders of the outstanding shares of capital stock of Celldex (the &#147;<b>Shares</b>&#148;) will receive the right to receive shares of common
stock of the Avant (the &#147;<b>Avant Common Stock</b>&#148;)
and, at the Effective Time (as defined in the Merger Agreement), options (the &#147;<b>Celldex Options</b>&#148;) to purchase Celldex common stock
outstanding will be assumed by Avant.&#160;
Capitalized terms used but not defined herein shall have the meanings
ascribed to them in the Merger Agreement.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; In order to
facilitate the transactions contemplated by the Merger Agreement, the undersigned
agrees that the undersigned will not, during the applicable Restriction Period
(as defined below), offer, sell, contract to sell, transfer, pledge, make any
short sale, hypothecate or otherwise dispose of, or reduce the undersigned&#146;s
interest in or risk relating to (each, a &#147;<b>Transfer</b>&#148;) any
shares of Avant Common Stock: (i)&nbsp;issued to the undersigned in connection
with the Merger in accordance with the terms of the Merger Agreement; (ii)&nbsp;issued
to the undersigned upon the exercise of any Celldex Options assumed by Avant in
accordance with the terms of the Merger Agreement; or (iii)&nbsp;otherwise
acquired or beneficially owned by the undersigned as a result of the
transactions contemplated by the Merger Agreement (collectively, the &#147;<b>Restricted
Shares</b>&#148;).&#160; For purposes
of this Agreement, the term &#147;<b>Restriction
Period</b>&#148; shall mean (i)&nbsp;with respect to the Restricted Shares
received by the undersigned pursuant to that certain Settlement Agreement,
dated as of October&nbsp;19, 2007 by and between the undersigned and Celldex (the
&#147;<b>Carve-Out Shares</b>&#148;), three months
after the Closing Date and (ii)&nbsp;with respect to the remaining Restricted
Shares, the first anniversary of the Closing Date.&#160; The undersigned will not have any
restrictions under this Agreement regarding the Transfer of the undersigned&#146;s
Restricted Shares after the expiration of the applicable Restriction Period;
provided, however, that the undersigned shall comply with all applicable laws,
including Rule&nbsp;144 promulgated</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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<div style="font-family:Times New Roman;">

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">under the Securities Act of 1933, in connection with
any Transfer of Carve-Out Shares prior to the first anniversary of the Closing
Date.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:34.55pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The foregoing
restriction is expressly agreed to preclude the undersigned from engaging in
any hedging or other transaction which is designed to or reasonably expected to
lead to, or result in, a sale or disposition of the Shares even if such shares
would be disposed of by someone other than the undersigned.&#160; Such prohibited hedging or other transactions
would include without limitation any short sale (whether or not against the
box) or any purchase, sale or grant of any right (including without limitation
any put or call option) with respect to any of the Shares or with respect to
any security that includes, relates to, or derives any significant part of its
value from such shares.&#160; Notwithstanding
the foregoing, nothing in this agreement shall prohibit (i)&nbsp;any grant or
exercise of options to purchase Common Stock pursuant to Avant&#146;s option plans
or (ii)&nbsp;the conversion of any equity security held by the undersigned into
Common Stock.</font></p>

<p style="margin:0in 0in .0001pt;page-break-after:avoid;text-indent:.5in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Notwithstanding</font><font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>foregoing,<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>restrictions<font size="1" style="font-size:8.0pt;">  </font>on<font size="1" style="font-size:8.0pt;">  </font>Transfer<font size="1" style="font-size:8.0pt;">  </font>set<font size="1" style="font-size:8.0pt;">  </font>forth<font size="1" style="font-size:8.0pt;">  </font>in<font size="1" style="font-size:8.0pt;">  </font>this<font size="1" style="font-size:8.0pt;">  </font>Agreement<font size="1" style="font-size:8.0pt;">  </font>shall<font size="1" style="font-size:8.0pt;">  </font>not<font size="1" style="font-size:8.0pt;">  </font>apply<font size="1" style="font-size:8
.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>(i)<font size="1" style="font-size:8.0pt;">  </font>transactions<font size="1" style="font-size:8.0pt;">  </font>relating<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>shares<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>Avant<font size="1" style="font-size:8.0pt;">  </font>Common<font size="1" style="font-size:8.0pt;">  </font>Stock<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>other<font size="1" style="font-size:8.0pt;">  </font>securities<font size="1" style="font-size:8.0pt;">  </font>acquired<font size="1" style="font-size:8.0pt;">  </font>in<font size="1" style="font-size:8.0pt;">  </font>open<font size="1" style="font-size:8.0pt;">  </font>market<font size="1" style="font-size:8.0pt;">  </font>transactions<font size="1" style="font-size:8.0pt;">  </font>after<font size="1" style
="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>Closing<font size="1" style="font-size:8.0pt;">  </font>Date,<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>(ii)<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>following<font size="1" style="font-size:8.0pt;">  </font>Transfers:<font size="1" style="font-size:8.0pt;">  </font>(A)<font size="1" style="font-size:8.0pt;">  </font><i>bona</i><i><font size="1" style="font-size:8.0pt;font-style:italic;">  </font>fide</i><font size="1" style="font-size:8.0pt;">  </font>gifts<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>family<font size="1" style="font-size:8.0pt;">  </font>members<font size="1" style="font-size:8.0pt;">  </font>(or<font size="1" style="font-size:8.0pt;">  </font>trusts<font size="1" style="font-size:8.0pt;">  </font>for<font size="1" style="font-size:8.0pt;">  <
/font>the<font size="1" style="font-size:8.0pt;">  </font>direct<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>indirect<font size="1" style="font-size:8.0pt;">  </font>benefit<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>family<font size="1" style="font-size:8.0pt;">  </font>members);<font size="1" style="font-size:8.0pt;">  </font>(B)<font size="1" style="font-size:8.0pt;">  </font><i>bona</i><i><font size="1" style="font-size:8.0pt;font-style:italic;">  </font>fide</i><font size="1" style="font-size:8.0pt;">  </font>charitable<font size="1" style="font-size:8.0pt;">  </font>contributions<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>Restricted<font size="1" style="font-size:8.0pt;">  </font>Shares<font size="1" style="font-size:8.0pt;">  </font>made<font size="1" style="font-size:8.0pt;">  </font>by<font size="1" style="font-size:8.0pt;">  </font>th
e<font size="1" style="font-size:8.0pt;">  </font>holder<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>such<font size="1" style="font-size:8.0pt;">  </font>Restricted<font size="1" style="font-size:8.0pt;">  </font>Shares;<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>(C)<font size="1" style="font-size:8.0pt;">  </font>Transfers<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>&#147;affiliates&#148;,<font size="1" style="font-size:8.0pt;">  </font>limited<font size="1" style="font-size:8.0pt;">  </font>partners,<font size="1" style="font-size:8.0pt;">  </font>members<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>stockholders<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>undersigned;<font size="1" sty
le="font-size:8.0pt;">  </font>provided<font size="1" style="font-size:8.0pt;">  </font>that<font size="1" style="font-size:8.0pt;">  </font>in<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>case<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>any<font size="1" style="font-size:8.0pt;">  </font>Transfer<font size="1" style="font-size:8.0pt;">  </font>pursuant<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>clause<font size="1" style="font-size:8.0pt;">  </font>(A),<font size="1" style="font-size:8.0pt;">  </font>(B)<font size="1" style="font-size:8.0pt;">  </font>or<font size="1" style="font-size:8.0pt;">  </font>(C),<font size="1" style="font-size:8.0pt;">  </font>each<font size="1" style="font-size:8.0pt;">  </font>transferee<font size="1" style="font-size:8.0pt;">  </font>agrees<font size="1" style="font-size:8.0pt;">  </font>in<font size="1" style="fon
t-size:8.0pt;">  </font>writing<font size="1" style="font-size:8.0pt;">  </font>as<font size="1" style="font-size:8.0pt;">  </font>a<font size="1" style="font-size:8.0pt;">  </font>condition<font size="1" style="font-size:8.0pt;">  </font>precedent<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>such<font size="1" style="font-size:8.0pt;">  </font>Transfer<font size="1" style="font-size:8.0pt;">  </font>to<font size="1" style="font-size:8.0pt;">  </font>be<font size="1" style="font-size:8.0pt;">  </font>bound<font size="1" style="font-size:8.0pt;">  </font>by<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>terms<font size="1" style="font-size:8.0pt;">  </font>hereof.<font size="1" style="font-size:8.0pt;">  </font>The<font size="1" style="font-size:8.0pt;">  </font>term<font size="1" style="font-size:8.0pt;">  </font>&#147;affiliate&#148;<font size="1" style="font-size:8.0pt;">  </font>shall<font size="1" s
tyle="font-size:8.0pt;">  </font>have<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>meaning<font size="1" style="font-size:8.0pt;">  </font>given<font size="1" style="font-size:8.0pt;">  </font>such<font size="1" style="font-size:8.0pt;">  </font>term<font size="1" style="font-size:8.0pt;">  </font>in<font size="1" style="font-size:8.0pt;">  </font>Rule<font size="1" style="font-size:8.0pt;">  </font>144<font size="1" style="font-size:8.0pt;">  </font>under<font size="1" style="font-size:8.0pt;">  </font>the<font size="1" style="font-size:8.0pt;">  </font>Securities<font size="1" style="font-size:8.0pt;">  </font>Act<font size="1" style="font-size:8.0pt;">  </font>of<font size="1" style="font-size:8.0pt;">  </font>1933,<font size="1" style="font-size:8.0pt;">  </font>as<font size="1" style="font-size:8.0pt;">  </font>amended.</p>

<p style="margin:0in 0in .0001pt;text-indent:34.2pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The undersigned
also agrees and consents to Avant entering stop transfer instructions with its
transfer agent and registrar against the Transfer of the Shares except in
compliance with the foregoing restrictions.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:34.2pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The undersigned
further represents and agrees that the undersigned has not taken and will not
take, directly or indirectly, any action which is designed to or which has
constituted or which would reasonably be expected to cause or result in
stabilization or manipulation of the price of any security of Avant to
facilitate the sale or resale of the Shares, or which has otherwise constituted
or will constitute any prohibited bid for or purchase of the Shares or any
related securities.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">6.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; It is understood
that if the Merger Agreement shall be terminated in accordance with the
provisions thereof at any time prior to the Closing Date, this Agreement shall terminate.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">7.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; This Agreement
shall be governed by and construed in accordance with the laws of the State of
Delaware.&#160; This Agreement may not be
amended, modified, revoked or terminated </font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>

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<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">in any respect without the written consent of the
undersigned and Avant.&#160; This Agreement
shall be binding upon the undersigned and the undersigned&#146;s heirs, successors
and assigns.</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3</font></p>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This agreement is executed as of the date first set forth above.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Very truly yours,</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">MEDAREX, INC.</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="51%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:51.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.44%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>
  </td>
  <td width="48%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:48.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ Howard H. Pien</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.44%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:48.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;Name: Howard H. Pien</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.44%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;Title: President and CEO</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.44%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;(if applicable)</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4</font></p>

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<DESCRIPTION>EX-99.3
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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 3</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">October&nbsp;19, 2007</font></p>

<p style="margin:0in 0in .0001pt 2.5in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 4.5in .0001pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.25pt;">AVANT Immunotherapeutics,&nbsp;Inc. </font></p>

<p style="margin:0in 4.5in .0001pt 0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">119
Fourth Avenue</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Needham,
MA 02194</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt 1.45in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Re:</font><font size="1" style="font-size:8.5pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><u style="letter-spacing:-.2pt;">Lockup Agreement (the </u><u style="letter-spacing:-.2pt;">&#147;<b>Agreement</b>&#148;)</u></p>

<p style="margin:0in 0in .0001pt .95in;"><font size="2" face="Times New Roman">&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">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.25pt;">1.</font><font size="1" style="font-size:8.5pt;letter-spacing:-.25pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:-.25pt;">The undersigned stockholder of Celldex Therapeutics,&nbsp;Inc.,
Delaware corporation </font>(&#147;Celldex&#148;),
understands that AVANT Immunotherapeutics,&nbsp;Inc., a Delaware corporation (&#147;AVANT&#148;),
and Callisto Merger Corporation., a Delaware corporation and a wholly-owned <font style="letter-spacing:-.1pt;">subsidiary of AVANT (the &#147;<b>Merger Sub</b>&#148;)<b>, </b>have entered into an Agreement and
Plan of Merger, dated as of October&nbsp;</font><font style="letter-spacing:-.1pt;">19</font><font style="letter-spacing:-.1pt;">,
2007 (as the same may be amended and restated from time to time, the </font><font style="letter-spacing:.1pt;">&#147;<b>Merger Agreement</b>&#148;)<b>, </b></font><font style="letter-spacing:.1pt;">with Celldex, pursuant to which the Merger Sub will
merge with and </font>into Celldex,
and, in connection therewith, holders of the outstanding shares of capital
stock of <font style="letter-spacing:.05pt;">Celldex (the &#147;<b>Shares</b>&#148;)
will receive the right to receive shares of common stock of the AVANT </font><font style="letter-spacing:.2pt;">(the &#147;<b>AVANT Common Stock</b>&#148;) and, at the
Effective Time (as defined in the Merger </font><font style="letter-spacing:.05pt;">Agreement), options (the &#147;<b>Celldex Options</b>&#148;) to purchase
Celldex common stock outstanding </font><font style="letter-spacing:.15pt;">will
be assumed by AVANT. Capitalized terms used but not defined herein shall have
the </font>meanings ascribed to them in the Merger Agreement.</p>

<p style="margin:0in .5in .0001pt 0in;text-indent:.5in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.25pt;">2.</font><font size="1" style="font-size:8.5pt;letter-spacing:-.25pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:-.2pt;">In order to facilitate the transactions contemplated by
the Merger Agreement, the </font>undersigned
agrees that the undersigned will not, until the six-month anniversary of the
Closing <font style="letter-spacing:.1pt;">Date (the &#147;<b>Restriction Period</b>&#148;), offer,
sell, contract to sell, transfer, pledge, make any short </font><font style="letter-spacing:-.1pt;">sale, hypothecate or otherwise dispose of, or reduce the undersigned&#146;s interest in or
risk relating<b>  </b></font><font style="letter-spacing:-.15pt;">to (each, a &#147;<b>Transfer</b>&#148;) any
shares of AVANT Common Stock: (i)&nbsp;issued to the undersigned in </font>connection
with the Merger in accordance with the terms of the Merger Agreement; (ii)&nbsp;issued
to <font style="letter-spacing:.1pt;">the undersigned upon the exercise of any
Celldex Options assumed by AVANT in accordance </font><font style="letter-spacing:-.2pt;">with the terms of the Merger Agreement; or (iii)&nbsp;otherwise acquired
or beneficially owned by the </font>undersigned as a result of the transactions
contemplated by the Merger Agreement (collectively, <font style="letter-spacing:-.1pt;">the &#147;<b>Restricted Shares</b>&#148;), The undersigned will not have any
restrictions under this Agreement </font><font style="letter-spacing:.25pt;">regarding
the Transfer of the undersigned&#146;s Restricted Shares after the expiration of the
</font>Restriction Period.</p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<div style="font-family:Times New Roman;">

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.05pt;">The foregoing restriction is expressly agreed to preclude
the undersigned from engaging </font><font style="letter-spacing:.1pt;">in any hedging or other transaction which is
designed to or reasonably expected to lead to, or </font><font style="letter-spacing:-.05pt;">result in, a sale or
disposition of the Shares even if such shares would be disposed of by someone </font><font style="letter-spacing:-.15pt;">other than the
undersigned. Such prohibited hedging or other transactions would include
without </font><font style="letter-spacing:.1pt;">limitation
any short sale (whether or not against the box) or any purchase, sale or grant
of any right (including without limitation any put or call option) with respect
to any of the Shares or with respect to any security that includes, relates to,
or derives any significant part of its value </font><font style="letter-spacing:-.05pt;">from such shares. Notwithstanding the foregoing,
nothing in this agreement shall prohibit (i)&nbsp;any </font><font style="letter-spacing:.1pt;">grant or exercise of
options to purchase Common Stock pursuant to AVANT&#146;s option plans or </font>(ii)&nbsp;the conversion of any equity
security held by the undersigned into Common Stock.</p>

<p style="margin:0in .05in .0001pt 0in;text-indent:.45in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.15pt;">3.</font><font size="1" style="font-size:8.5pt;letter-spacing:.15pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:.15pt;">Notwithstanding the foregoing, the restrictions on
Transfer set forth in this </font><font style="letter-spacing:.1pt;">Agreement shall not apply to (i)&nbsp;transactions
relating to shares of AVANT Common Stock or </font><font style="letter-spacing:-.15pt;">other securities acquired in open market
transactions after the Closing Date, or (ii)&nbsp;the following </font><font style="letter-spacing:.1pt;">Transfers: (A)&nbsp;<i>bona fide </i>gifts to family members (or
trusts for the direct or indirect benefit of </font><font style="letter-spacing:.05pt;">family members); (B)&nbsp;<i>bona </i></font><i style="letter-spacing:.55pt;">fide </i><font style="letter-spacing:.05pt;">charitable contributions
of Restricted Shares made by the holder </font><font style="letter-spacing:.25pt;">of such Restricted Shares; or (C)&nbsp;Transfers
to &#147;affiliates&#148;, limited partners, members </font><font style="letter-spacing:.25pt;">or </font><font style="letter-spacing:.1pt;">stockholders of the undersigned; provided that in the case
of any Transfer pursuant to clause </font>(A),
(B)&nbsp;or (C), each transferee agrees in writing as a condition precedent to
such Transfer to be <font style="letter-spacing:.25pt;">bound by the terms
hereof. The term &#147;affiliate&#148; shall have the meaning given such term in </font>Rule&nbsp;144
under the Securities Act of 1933, as amended.</p>

<p style="margin:0in .05in .0001pt 0in;text-indent:.55in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.15pt;">4.</font><font size="1" style="font-size:8.5pt;letter-spacing:.15pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:-.25pt;">The undersigned also agrees and consents to AVANT
entering stop transfer </font><font style="letter-spacing:-.2pt;">instructions with its transfer agent and registrar
against the Transfer of the Shares except in </font>compliance with the foregoing restrictions.</p>

<p style="margin:0in .45in .0001pt 0in;text-indent:.55in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.15pt;">5.</font><font size="1" style="font-size:8.5pt;letter-spacing:.15pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:-.05pt;">The undersigned further represents and agrees that the
undersigned has not taken </font><font style="letter-spacing:.05pt;">and will not take, directly or indirectly, any action
which is designed to or which has constituted </font>or which would reasonably be expected to cause or result in
stabilization or manipulation of the <font style="letter-spacing:.2pt;">price of
any security of AVANT to facilitate the sale or resale of the Shares, or which
has </font>otherwise constituted or will constitute any prohibited bid for or
purchase of the Shares or any related securities.</p>

<p style="margin:0in .05in .0001pt 0in;text-indent:.55in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.15pt;">6.</font><font size="1" style="font-size:8.5pt;letter-spacing:.15pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>It
is understood that if the Merger Agreement shall be terminated in accordance <font style="letter-spacing:.05pt;">with the provisions thereof at any time prior to
the Closing Date, this Agreement shall terminate.</font></p>

<p style="margin:0in .05in .0001pt 0in;text-indent:.55in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:.15pt;">7.</font><font size="1" style="font-size:8.5pt;letter-spacing:.15pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:.05pt;">This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware. This Agreement may not be
amended, modified, revoked or terminated </font><font style="letter-spacing:.2pt;">in any respect without the written consent of the
undersigned and AVANT. This Agreement </font><font style="letter-spacing:.05pt;">shall be binding upon the undersigned and the
undersigned&#146;s heirs, successors and assigns.</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

</div>
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<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This agreement
is executed as of the date first set forth above.</font></p>

<p style="margin:0in 0in .0001pt .45in;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Very truly
  yours,</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">CHARLES R.
  SCHALLER</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="border:none;padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(print name
  of stockholder above)</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:48.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.34%;">
  <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:45.54%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ Charles
  R. Schaller</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.34%;">
  <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="border:none;padding:0in 0in 0in 0in;width:45.54%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:&nbsp;CHARLES
  R. SCHALLER</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.34%;">
  <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:45.54%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&nbsp;CHAIRMAN,
  CELLDEX</font></p>
  </td>
 </tr>
 <tr>
  <td width="51%" valign="top" style="padding:0in 0in 0in 0in;width:51.12%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.34%;">
  <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:45.54%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(if applicable)</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3</font></p>

<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>

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