AVANT ANNOUNCES COMPLETED MERGER

AVANT ANNOUNCES COMPLETED MERGER

AND 1-FOR-12 REVERSE STOCK SPLIT

Results of Shareholder Meeting also Announced All Resolutions

MA (March 7, 2008): AVANT Immunotherapeutics, Inc. (Nasdaq:

AVAN) announced today the completed merger of Callisto Merger Corporation, its

wholly-owned subsidiary, with and into Celldex Therapeutics, Inc.,

resulting in the combined company which will continue to be named AVANT and

trade under the NASDAQ ticker symbol AVAN.

are extremely pleased that our shareholders recognized the intrinsic value of

this merger and believe that with the closing of this transaction we have built

a strong, diversified company, said Dr. Una Ryan, President and CEO of

AVANT. We look forward to making substantial progress in the development of

our portfolio of immunotherapy candidates and communicating this progress to

our shareholders throughout the year. We thank them for their continued

The combined company is built on mutual expertise in

developing novel immunotherapy products and brings together an exceptional

management team with proven experience in all aspects of drug development. We

believe that these key attributes create a stronger AVANT to realize the

potential of our novel immunotherapy candidates, said Charles Schaller,

Chairman of Celldex. I look forward to working with the new AVANT team to

advance the Company s promising pipeline.

104.8 million shares (on a pre-split basis) are being issued to the former

Celldex shareholders in connection with the merger, having a value of

approximately $75 million.

the terms of the merger agreement, Celldex shareholders will receive approximately

4.96 shares of common stock in exchange for each share of Celldex common stock

and Class A common stock they own.

AVANT stockholders will retain 42% of, and the former Celldex

stockholders will own 58% of, the outstanding shares of AVANT s common stock on

a fully-diluted basis. AVANT will also assume all of Celldex s stock options

outstanding at the time of the merger.

the special meeting of AVANT shareholders held on March 6, 2008 in

connection with the merger, shareholders approved four proposals: (i) the

issuance of shares of AVANT common stock pursuant to

NEEDHAM, MA 02494-2725 USA 781-433-0771 FAX

781-433-0262 www.avantimmune.com

merger agreement in the amount necessary to result in the Celldex stockholders

owning 58% of AVANT common stock on a fully diluted basis, (ii) an

amendment to AVANT s Third Restated Certificate of Incorporation to increase

the number of authorized shares to 300,000,000, (iii) an amendment to

AVANT s Third Restated Certificate of Incorporation to effect a reverse stock

split in a ratio ranging from one-for-twelve to one-for-twenty of all issued

and outstanding shares of AVANT common stock, the final ratio to be determined

within the discretion of the AVANT board of directors and (iv) adoption of

the 2008 stock option and incentive plan.

board of directors has approved a 1-for-12 reverse stock split of AVANT s

common stock, which became effective today, March 7, 2008. As a result of

the reverse stock split, each twelve shares of common stock will be combined

and reclassified into one share of common stock and the total number of shares

outstanding will be reduced from approximately 180 million shares (including

the shares issued to Celldex shareholders in connection with the merger) to

approximately 15 million shares.

AVANT common stock will trade under the symbol AVAND for 20 trading days

beginning on March 10, 2008 to designate that it is trading on a

post-reverse split basis, and will resume trading under the symbol AVAN after

the 20-day period has expired.

AVANT Immunotherapeutics, Inc.:

Immunotherapeutics, Inc. is a NASDAQ-listed company discovering and

developing innovative vaccines and targeted immunotherapeutics for the

treatment of cancer, infectious and inflammatory diseases. AVANT focuses on the use of tumor-specific

targets and human monoclonal antibodies (mAbs) to precisesly deliver

therapeutic agents through its novel targeted immunization approach. AVANT also possesses innovative bacterial

vector delivery technologies with unique manufacturing and preservation

processes that offer the potential for a new generation of infectious disease

vaccines. AVANT has three commercialized products, including Rotarix

for the prevention of rotavirus infection and two human food safety vaccines

for reducing salmonella infection in chickens and eggs. AVANT s deep product

pipeline consists of products in varying stages of development, with its lead

candidate, CDX-110, currently undergoing evaluation in a Phase 2/3 clinical

trial in newly diagnosed glioblastoma multiforme, one of the most aggressive

forms of brain cancer. AVANT also has

five product candidates in its development pipeline including:

CDX-1307, a product based on its proprietary APC Targeting Technology(TM), which is in two Phase 1 clinical trials for patients with advanced pancreatic, bladder, breast and colon cancer;

a complement inhibitor, TP10, in development for transplantation and other indications; and

three candidates based on its oral, rapidly-protecting, single-dose and temperature-stable vaccine technology, including combination vaccines for travelers, the military and global health needs.

information on AVANT Immunotherapeutics, Inc. can be obtained through our

site on the World Wide Web: http://www.avantimmune.com.

Safe Harbor Statement Under the Private

Securities Litigation Reform Act of 1995: The

statements made in this press release which are not statements of historical

fact are forward-looking statements within the meaning of Section 27A of

the Securities Act of 1933 and Section 21E of the Securities Exchange Act

of 1934, including, without limitation, statements that may be identified by

words such as expectations, remains, focus, expected, prospective, expanding,

building, continue, progress, plan, efforts, hope, believe, objectives,

opportunities, will, seek, and other expressions which are predictions of

or indicate future events and trends and which do not constitute historical

matters identify forward-looking statements. These statements also include statements regarding: (i) AVANT s

expectations regarding its integration with Celldex following the merger and (ii) statements

made regarding AVANT s goals for its programs and products. This release

includes forward-looking statements that are subject to a variety of risks and

uncertainties and reflect AVANT s current views with respect to future events

and financial performance. There

are a number of important factors that could cause the actual future experience

and results to differ materially from those expressed in any forward-looking

statement made by AVANT, including, but are not limited to: (i) costs

related to the merger; (ii) the risk that AVANT s and Celldex s businesses

will not be integrated successfully; (iii) the combined company s