Exhibit 99.1

Shalini Sharp to Succeed Peter Thornton as Antigenics' Chief Financial Officer

    NEW YORK--(BUSINESS WIRE)--July 24, 2006--Antigenics Inc. (NASDAQ:
AGEN) today announced that Shalini Sharp, currently senior director of
strategic planning and corporate development, will be appointed as the
company's chief financial officer and vice president as of September
30. Peter Thornton, who has been CFO since 2004, will be stepping down
and plans to return to Ireland with his family.
    "The decision to leave Antigenics has been a difficult one. It has
been both a pleasure and a privilege to work with Antigenics,
surrounded by people of integrity and enormous energy and vision,"
said Mr. Thornton.
    "Peter has done an outstanding job in bringing Antigenics'
financial capabilities to the top tier. Just as importantly, he is
also an individual of incomparable integrity and personal and
management qualities," said Garo H. Armen, PhD, chairman and CEO of
Antigenics. "Shalini has provided us with indispensable strategic and
financial counsel over the years. With her impeccable credentials and
knowledge of our company, we anticipate a particularly seamless
transition. As a member of our executive management team, she will
continue to contribute in her exceptional strategic capacity as well
as assuming the additional operational role with which she has worked
so closely in the past."
    Since joining Antigenics in 2003, Ms. Sharp has been a member of
the senior management team, managing strategic planning, investor
relations, and financing and acquisition transactions. Prior to this,
she was director of strategic planning at Elan Corporation, plc.,
where she served as chief of staff to the chairman of the board during
the restructuring process and drove to completion a number of
strategic corporate and financial transactions. Ms. Sharp was
previously a management consultant at McKinsey & Company, specializing
in pharmaceuticals and medical devices. She has also worked in
investment banking at Goldman, Sachs & Company, primarily in the
health care field. She received her BA and MBA from Harvard
University.
    Antigenics also announced that Christine Klaskin has been promoted
from director to vice president of finance. Ms. Klaskin joined
Antigenics in 1996, after working as an audit manager at Arthur
Andersen. A certified public accountant, she earned her Bachelor of
Accountancy from The George Washington University. Ms. Klaskin will
report in to Ms. Sharp.

    About Antigenics

    Antigenics (NASDAQ: AGEN) is working to develop treatments for
cancers, infectious diseases and autoimmune disorders. The company's
investigational product portfolio includes Oncophage(R) (vitespen), a
patient-specific therapeutic cancer vaccine being evaluated in several
indications; Aroplatin(TM), a liposomal, third-generation platinum
chemotherapeutic; ATRA-IV, a liposomal retinoic acid; AG-707, a
therapeutic vaccine for the treatment of genital herpes; AU-801, a
preclinical program targeting autoimmune disorders; and QS-21, an
adjuvant being evaluated by Antigenics' corporate partners in several
late-stage clinical trials. For more information, please visit
www.antigenics.com.

    This press release contains forward-looking statements, including
statements regarding the transition of responsibilities from Mr.
Thornton to Ms. Sharp, and Ms. Sharp's anticipated future
contributions to the company's strategy and operations. These
statements are subject to risks and uncertainties that could cause
actual results to differ materially from those projected in these
forward-looking statements. Risks and uncertainties include, among
others, the risk of disruption or loss of continuity that may be
associated with management transition; 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 May 12, 2006. 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. The prior track record of Ms. Sharp does not assure
Antigenics' future success.

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