Data from Phase I Trial of Oncophage Cancer Vaccine in Pancreatic Cancer Highlighted at European Cancer Conference -ECCO 12-.

Business Editors/Health/Medical Writers

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COPENHAGEN, Denmark--(BUSINESS WIRE)--Sept. 22, 2003

         Overall Survival of 2.5 Years Reported in Pancreatic
      Cancer Patients Receiving Oncophage; Findings From Phase II
      Trial of Aroplatin(TM) in Colorectal Cancer Also Presented

Antigenics Inc. (NASDAQ: AGEN), the world leader in heat shock protein technology, announced results from a Phase I clinical trial of the company's personalized cancer vaccine Oncophage(R) (HSPPC-96) in patients with nonmetastatic pancreatic cancer, which were highlighted today in an oral presentation at the annual European Cancer Conference (ECCO 12) as well as in a press release issued by the Federation of European Cancer Societies.

In the pilot study, which included 10 evaluable patients, manufacture of personalized Oncophage vaccines was feasible and no toxicity associated with vaccination was observed. Patients in the trial experienced a median overall survival of 2.5 years, with one patient still alive and disease-free after more than five years, and two other patients alive and disease-free 2.5 and 2.2 years after treatment.

"What is notable about these findings is the duration of survival observed in the study, as more than 90 percent of patients with pancreatic cancer die within two years of diagnosis despite surgical treatment," said Robert G. Maki, MD, PhD, Assistant Member of the Department of Medicine at Memorial Sloan-Kettering Cancer Center, and lead investigator on the study. "Combined with the lack of dose-limiting toxicity observed in the trial, the preliminary results are promising and support the further evaluation of Oncophage in pancreatic cancer."

The trial evaluated 10 patients with pancreatic cancer who had undergone pancreatic resection (removal of part of the pancreas), the standard operative treatment for pancreatic cancer. Cancerous tissue obtained from the surgery was used to produce personalized Oncophage vaccine for each patient. Within eight weeks of surgery, study subjects began Oncophage treatment, which consisted of one vaccination per week for four weeks.

"Compared with an historical median survival of about 16 months for patients with resected pancreatic cancer, the median survival of 30 months observed in the trial is encouraging," said Jonathan J. Lewis, MD, PhD, chief medical officer of Antigenics and co-author on the study. "These early data are promising and consistent with what we have observed in many different cancers."

Derived from each individual's tumor, Oncophage contains the 'antigenic fingerprint' of the patient's particular cancer, and is designed to reprogram the body's immune system to target and destroy only cancer cells bearing this fingerprint. Oncophage is intended to leave healthy tissue unaffected and limit the debilitating side effects associated with traditional cancer treatments such as chemotherapy and radiation therapy. Currently in late-stage development, Oncophage has been granted fast track and orphan drug designations from the US Food and Drug Administration in both metastatic melanoma and kidney cancer.

Encouraging Phase II Data on Aroplatin in Colorectal Cancer Also Presented

Antigenics also presented findings from a Phase II trial of Aroplatin in metastatic colorectal cancer refractory to standard therapy. Aroplatin is a novel liposomal formulation of a third-generation platinum chemotherapeutic that is structurally similar to oxaliplatin, a recently approved treatment for colorectal cancer.

The single-arm, open-label trial, being conducted at the Arizona Cancer Center, is evaluating the effect of Aroplatin monotherapy in patients whose disease is not responsive to standard first-line cancer treatments (5-fluorouracil/leucovorin or capecitabine and irinotecan). To date, one out of the 15 evaluable patients has demonstrated a partial clinical response and two have experienced disease stabilization. In addition, researchers observed that Aroplatin appears well tolerated in this heavily pretreated patient population.

About Pancreatic and Colorectal Cancers

The American Cancer Society estimates that 30,700 people in the United States will be diagnosed with pancreatic cancer this year and that about 30,000 will die of the disease, making it the fourth leading cause of cancer death in men and women. Most people with pancreatic cancer are over 60 years old when the cancer is found, and the disease is somewhat more common in men than in women.

Together, cancers of the colon and rectum are among the most common cancers in the United States. This year, it is estimated that there will be about 107,300 new cases of colon cancer and 41,000 new cases of rectal cancer, together causing almost 57,000 deaths. They occur in both men and women and are most often found among people who are over the age of 50. The three main types of treatment for colorectal cancer are surgery, radiation therapy and chemotherapy.

About Antigenics

Antigenics is working to develop personalized immunotherapeutics and revolutionary treatments for cancers, infectious diseases and autoimmune disorders. The company's lead product candidate is Oncophage, a late-stage, personalized cancer vaccine being evaluated in several indications, including kidney cancer and metastatic melanoma. Antigenics' portfolio also includes AG-858, a personalized cancer vaccine in Phase II development; Aroplatin and ATRA-IV, two Phase II liposomal chemotherapeutics; and AG-702/AG-70X, a Phase I genital herpes immunotherapeutic. For more information about Antigenics, please visit www.antigenics.com.

This press release contains forward-looking statements, including the statements regarding the implications of the preliminary results of the pilot study of Oncophage in pancreatic cancer; the potential of Oncophage to address a medical need for patients with pancreatic cancer; and the planned continued enrollment for the Phase II trial of Aroplatin in metastatic colorectal cancer. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in these forward-looking statements. Although the data for the Phase I pancreatic trial are encouraging, later trials may fail to duplicate these results. Phase I trials are not designed to establish efficacy of a product candidate. Significant additional trials and regulatory approvals would be required prior to commercializing Oncophage in patients with nonmetastatic pancreatic cancer. Similarly, the preliminary findings from the Phase II trial of Aroplatin in metastatic colorectal cancer may not be indicative of the final results of the trial or results obtained in any future trials. Risks and uncertainties associated with biotechnology product development and commercialization activities include, among others, that our clinical trials may not demonstrate that our products are both safe and more effective than current standards of care; that we may be unable to obtain the regulatory approvals necessary to conduct additional clinical trials or to market our products; that budget constraints will limit or slow down our development programs; that we may fail to adequately protect our intellectual property or are determined to infringe on the intellectual property of others; and the factors described in the company's periodic filings with the Securities and Exchange Commission. Please see Exhibit 99.1 of the Antigenics Quarterly Report on Form 10-Q for the quarter ending June 30, 2003, for a discussion of these and other risk factors. In addition, Antigenics announced on September 3 that the FDA has requested additional product characterization information and that, pending receipt and acceptance of such information, the FDA placed on partial clinical hold the Phase III trials of Oncophage under its investigational new drug (IND) application, which includes trials in kidney cancer and metastatic melanoma. Antigenics cautions investors not to place undue reliance on the forward-looking statements contained in this press release. These statements speak only as of the date of this document, and Antigenics undertakes no obligation to update or revise the statements. All forward-looking statements are expressly qualified in their entirety by this cautionary statement.