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                                                                    EXHIBIT 99.1

                       ANTIGENICS COMPLETES ACQUISITION OF
                             ARONEX PHARMACEUTICALS

       COMBINED COMPANY EXPECTS TO FILE TWO NEW DRUG APPLICATIONS IN 2002

NEW YORK, NEW YORK - JULY 12, 2001 - Antigenics Inc. (Nasdaq: AGEN) announced
today the completion of its acquisition of Aronex Pharmaceuticals, Inc. (Nasdaq:
ARNX) following the approval by Aronex Pharmaceuticals' shareholders. The
acquisition adds two advanced-stage cancer products to Antigenics' portfolio of
22 clinical trial programs in cancer, infections, and immune and degenerative
disorders.

The merged company now includes Aronex Pharmaceuticals' four mid- to late-stage
development products: ATRAGEN(R), an intravenous formulation of ATRA
(all-trans-retinoic acid) for the treatment of leukemia and other cancers;
Nyotran(R), a novel formulation of a widely used topical polyene anti-fungal
drug in Phase III development; Aroplatin(TM), a novel platinum analogue designed
to overcome the kidney toxicity and biochemical resistance associated with
current platinum drugs used in the treatment of cancer; and Annamycin, a novel
anthracycline analogue designed to overcome heart toxicity associated with
current anthracyclines. These new drugs support Antigenics' goal to design
safer, less toxic therapies for serious diseases.

"The acquisition of Aronex Pharmaceuticals is a substantial advancement towards
expanding Antigenics' cancer franchise, diversifying our therapy portfolio with
an additional technology platform and accelerating our expected commercial
product introduction by a full year to 2002," said Garo H. Armen, Ph.D.,
chairman and CEO of Antigenics. "Antigenics' world-class immune products in
late-stage development combined with Aronex Pharmaceuticals' liposome delivery
products position us as an industry leader with a deep arsenal of treatments."

Antigenics' experienced regulatory team is working with the U.S. Food and Drug
Administration to address concerns expressed in a non-approval letter for
ATRAGEN(R), which was received by Aronex Pharmaceuticals in January 2001. The
company is optimistic that all its products will continue to move forward
towards regulatory approval.

Under the terms of the merger agreement announced on April 24, 2001, Aronex
Pharmaceuticals' shareholders will receive 0.0594 shares of Antigenics' shares
for each of their Aronex Pharmaceuticals' shares. In addition, each share of
Aronex Pharmaceuticals common stock will be entitled to a contingent value right
potentially worth an additional $0.15. The acquisition is expected to be
accretive to Antigenics' earnings starting in 2003.

Antigenics Inc. is developing treatments for cancer, infection and immune and
degenerative disorders using its proprietary technology platforms. Antigenics'
lead cancer
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vaccine, Oncophage(R), in Phase III clinical development, is based on pioneering
technology that uses HSPs to activate the immune system against cancer.
Antigenics' antibody based products and technologies include Leucogen(R)
vaccination against feline leukemia virus (approved for U.S. and European use in
1991), Quilimmune-P for aiding the prevention of pneumococcal infections in the
elderly, and Quilimmune-M for aiding the prevention of malaria. The company also
licenses its immune enhancement technologies to pharmaceutical partners
including: GlaxoSmithKline, Elan Corporation, plc, Aventis Pasteur, Wyeth
Lederle, VaxGen, Progenics Pharmaceuticals, Green Cross Vaccine Corporation and
Virbac S.A. For more information about Antigenics visit www.antigenics.com.
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This press release contains forward-looking statements. These include statements
about the filing of the NDA's, the future commercialization of Antigenics'
products and when the acquisition will be accretive. Several risks and
uncertainties could cause actual results to differ materially from those
projected in the forward-looking statements. These factors include the ability
to satisfy regulatory requirement (including obtaining FDA approval to market
ATRAGEN(R)), the outcome of clinical trials, the efficacy of products that are
commercialized, the ability to convince the medical community to adopt products,
competition from pharmaceutical and biotechnology companies, the strength of
intellectual property rights, the ability to raise capital and other risks
identified in the Antigenics' SEC filings.