Exhibit 99.1


                    Antigenics Updates Business Strategy and
     Outlines Timeline for the Analysis of Its Phase 3 Kidney Cancer Trial

    NEW YORK--(BUSINESS WIRE)--Dec. 6, 2005--Antigenics Inc.:

    --  Company Presents Clinical Development and Funding Scenarios

    --  Interim Strategy Will Result in Significant Reduction in Burn
        Rate to Approximately $40 Million

    --  Results of Phase 3 Kidney Cancer Trial Expected in March 2006

    Antigenics Inc. (NASDAQ: AGEN) today announced that the analysis
of data from its kidney cancer trial of Oncophage(R) (vitespen;
formerly HSPPC-96) will be completed in March 2006, and that an
interim strategy designed to maximize shareholder value will be
implemented. This strategy will significantly reduce burn rate and
focus operations on the company's highest potential products and
programs.
    "We have elected to take decisive and prudent actions now in order
to preserve our cash and position the company to maximize the full
value of our diverse portfolio," said Garo H. Armen, PhD, chairman and
CEO of Antigenics.
    The company indicated that the blinded review by an independent
panel of three radiologists and an oncologist of its Phase 3 trial in
renal cell carcinoma (RCC; the most common form of kidney cancer) is
expected to be completed in March 2006, with top-line data available
shortly thereafter.
    If the data from this 728-patient trial are positive, Antigenics
will pursue partnering and/or financing transactions that put the
company in a position to (1) bring Oncophage to the market
expeditiously; and (2) develop the company's priority programs in
clinical and preclinical research, with an aim to rapidly partner
these products.
    Alternatively, if the kidney cancer trial results are not
positive, the company will continue to pursue Phase 2 trials of
Oncophage in combination therapy. This effort is supported by
significant activity demonstrated in preclinical studies of Oncophage
combined with chemotherapeutic and biological agents. In addition, the
company will continue with its other priority preclinical and clinical
research programs, financed initially through the company's own cash
reserves.
    The company also plans to submit to the US Food and Drug
Administration (FDA) the results of its tests measuring the potency of
Oncophage from both the kidney cancer and melanoma Phase 3 trials.
These tests have been completed on all patient product samples; the
results indicate that 96 percent of the Oncophage vaccines used in
these trials met potency specifications, as measured by two different
assays.
    Independent of the outcome of the kidney cancer trial, Antigenics
is working to bring to the clinic Oncophage made through an improved
manufacturing process. Product made with this process has shown
significantly higher activity than that made with the current process.
    The company's strategy also calls for the continued use of company
funds for clinical development of Aroplatin in cancer and AG-707 in
genital herpes. Preclinical research will focus on autoimmune diseases
with the goal of bringing a lead compound to the clinic in the first
half of 2007. All other clinical and preclinical or research programs
have been either postponed or decelerated.
    The company today has also taken steps to reduce its headcount
from 251 at the end of the third quarter to approximately 170
employees. The company estimates that severance and other costs will
be approximately $2 million, the majority of which will be incurred by
December 31, 2005.
    Antigenics anticipates that these cost-cutting measures will
result in significant cost savings, starting immediately, and that the
company's net cash burn rate (cash used in operating activities plus
cash from investing activities and debt repayments), exclusive of any
program sponsorship from third party sources, will be reduced for the
near term to approximately $40 million per year by the second quarter
of 2006.
    "We are streamlining our operations and narrowing our focus to
those compounds that can generate meaningful and measurable milestones
within the next 24 months," said Dr. Armen. "We believe our updated
business strategies give us a realistic and attainable approach for
the various contingencies that may arise in the coming period."

    Top priorities for clinical and preclinical research programs are:

    --  Phase 3 analysis evaluating Oncophage in kidney cancer is
        expected in late March 2006.

    --  Phase 3 final Oncophage data in melanoma are expected in March
        2006.

    --  Combination therapies with Oncophage and other agents in small
        clinical trials will evaluate tumor response in patients with
        stage IV disease. The first investigational new drug (IND)
        application will be filled by year-end, with additional INDs
        to be filed in 2006. Data should be available within 12 to 18
        months of first patient enrollment.

    --  Phase 1 dose-escalating trial of the reformulated Aroplatin in
        solid malignancies and B-cell lymphoma is ongoing. This trial
        will also measure tumor response in stage IV patients, with
        data expected within 12 to 18 months of trial commencement.

    --  Phase 1 trial with AG-707, a therapeutic vaccine directed at
        the virus that causes genital herpes, is ongoing. This trial
        measures immunological responses and recurrence of herpes.
        Data are expected in early to mid 2007, with the goal of
        partnering this program upon positive outcomes.

    --  Preclinical studies of higher-activity Oncophage made through
        an improved process are to be completed by the third quarter
        of 2006. Antigenics plans to initiate clinical trials with
        this product in stage IV cancer patients in the first half of
        2007.

    --  Clinical trials of AU-801 for the treatment of autoimmune
        diseases are slated for the first half of 2007.

    About Antigenics

    Antigenics is working to develop patient-specific
immunotherapeutics and revolutionary treatments for cancers,
infectious diseases and autoimmune disorders. The company's lead
product candidate is Oncophage(R) (vitespen; formerly HSPPC-96), a
late-stage, patient-specific cancer vaccine being evaluated in several
indications, including renal cell carcinoma and metastatic melanoma.
Antigenics' portfolio of investigational products also includes AG-858
(HSPPC-70), a patient-specific cancer vaccine in Phase 2 development;
two liposomal cancer treatments, Aroplatin(TM) and ATRA-IV; and
AG-707, a Phase 1 genital herpes vaccine.

    This press release contains forward-looking statements, including
statements regarding Antigenics' potential commercialization of
Oncophage if the Phase 3 RCC trial results are positive, the timing of
final analysis of the data from the Phase 3 trials in melanoma and
RCC, plans to commence and timing of new clinical trials, expectation
that trials will support regulatory filings, timing of regulatory
submissions, projected enrollment in trials, the magnitude of cost
reductions, and that the steps described in this press release will
maximize the value of the product portfolio and shareholder value. It
also contains forward-looking statements regarding preclinical and
manufacturing process development as well as partnering and financing
opportunities. All of these forward-looking statements are subject to
risks and uncertainties that could cause actual results to differ
materially. These risks and uncertainties include, among others, the
timing of events in the RCC trial, the results of clinical trials,
decisions by regulatory agencies, the cost of additional clinical
trials, the outcome of process and preclinical development activities,
the ability to raise additional capital, and the factors described
under Factors That May Impact Future Results in the Management's
Discussion and Analysis of Financial Condition and Results of
Operations section of Antigenics' Form 10-Q as filed with the
Securities and Exchange Commission on November 4, 2005. Antigenics
cautions investors not to place considerable 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. Antigenics' business is subject to
substantial risks and uncertainties, including those identified above.
When evaluating Antigenics' business and securities, investors should
give careful consideration to these risks and uncertainties.


    CONTACT: Antigenics Inc.
             Corporate Communications:
             Sunny Uberoi, 212-994-8206
             suberoi@antigenics.com
             or
             Investor Relations:
             Shalini Sharp, 800-962-2436
             ir@antigenics.com