December 2007

Dear Shareholders,

The fourth quarter of 2007 was transformative for AVANT Immunotherapeutics, Inc. On October 22, we announced a proposed merger with privately held Celldex Therapeutics, Inc. to create a fully integrated biopharmaceutical company with a deep pipeline of high value product candidates diversified across multiple therapeutic areas and stages of development. We are very excited about this opportunity and believe it will accelerate growth and product development—resulting in increasing value for our investors. We look forward to shareholder and SEC approval in the New Year.

The combined company will build on the deep immunology expertise of both AVANT and Celldex to develop vaccine and human monoclonal antibodies product candidates in high-value underserved markets, including oncology, infectious and inflammatory diseases. The most advanced candidates include:

• CDX-110, a novel cancer immunotherapy, currently enrolling patients in a Phase 2/3 trial for the treatment of brain cancer (glioblastoma multiforme); and
• CholeraGarde®, a single-dose oral vaccine, entering Phase 2 and 3 field trials in India and Bangladesh, supported by $21 million in funding from the Gates Foundation through the International Vaccine Institute’s (IVI) Cholera Vaccine Initiative; and
• Ty800, a single-dose oral typhoid fever vaccine, expecting clinical results in the first half of 2008 from a fully enrolled Phase 2 trial in the U.S.

Our deep clinical-stage pipeline also includes multiple products in the areas of cancer immunotherapy, as well as AVANT’s ETEC-cholera combination vaccine for travelers, and TP10 in transplantation, age-related macular degeneration (AMD) and other inflammatory indications. This pipeline will be fueled internally by two strong technology platforms:

• Celldex’s proprietary APC Targeting Technology™, which utilizes human monoclonal antibody (mAb) technology to generate tumor-specific immune responses, enabling the development of targeted immunotherapeutics for a variety of tumor types; and
  
• AVANT’s innovative vector vaccine delivery, manufacturing and preservation technologies—the technology behind our single dose, oral, rapidly protecting vaccines for cholera and typhoid fever.

The first product candidate generated through APC Targeting Technology, CDX-1307, has already entered clinical trials and is being studied in a variety of solid tumor types including colorectal, bladder, pancreas and breast. AVANT also recently announced the application of our vector vaccine technology toward the development of a “super-enteric” vaccine designed to combine protection against multiple diseases in a single product. The National Institute of Allergy & Infectious Disease will sponsor a Phase 1 clinical trial to begin in early 2008 studying an initial combination cholera and enterotoxigenic E. coli (ETEC) vaccine. Ultimately, our goal is to develop a single oral dose vaccine that combines the ETEC-cholera construct with the Ty800 vaccine construct to provide rapid protection against the three major causes of severe diarrheal illness for travelers, the military and global health needs. We recently presented preclinical data supporting the feasibility of such an approach at a leading international research meeting.

In addition to our deep pipeline, the proposed merger will create a management team with significant depth in both corporate leadership and the clinical development of innovative products. The merger also maximizes AVANT’s expertise in manufacturing. Upon closing of the merger, manufacturing of Celldex candidates will be brought in-house to AVANT’s Fall River facility eliminating the uncertainties, risks and costs of contract management and ensuring the highest level of quality control.

As we look to the New Year, we anticipate a great deal of exciting news from our promising clinical programs. We thank you for your continued support and look forward to reporting significant progress at AVANT in 2008.

Yours sincerely,

Una S. Ryan, Ph.D., O.B.E.
President and CEO
AVANT Immunotherapeutics, Inc.