Medarex Initiates Phase I Clinical Trial of MDX-010 in HIV

Medarex Initiates Phase I Clinical Trial of MDX-010 in HIV
    PRINCETON, N.J., June 11 /PRNewswire-FirstCall/ --
Medarex, Inc. (Nasdaq: MEDX) today announced the initiation of a Phase I
clinical trial of MDX-010, a fully human anti-CTLA-4 antibody, for patients
infected with HIV, the causative agent of AIDS.

    This multi-center, open-label clinical trial is expected to enroll up to
18 patients with HIV who have an extensive treatment history but whose virus
is no longer suppressed by highly active antiretroviral therapy (HAART).
Patients are expected to receive two monthly doses of the MDX-010 antibody in
this dose-escalation study. The trial is designed to establish safety and
tolerability of MDX-010 in patients infected with HIV, and to preliminarily
evaluate clinical efficacy.  The trial will include assessments of viral load
and CD4 counts in patients, as well as immune responses to HIV and other
antigens.

    "We believe that MDX-010 is showing promise in cancer treatment, and that
it may also have the potential to enhance the immune systems of AIDS
patients," said Donald L. Drakeman, President and CEO of Medarex.

    "The ability to boost the potency of the cellular immune response against
HIV could be crucial in allowing patients to control the virus with their own
immune systems," said Israel Lowy, M.D. Ph.D., Director of Infectious Diseases
at Medarex. "If MDX-010 can boost anti-HIV immunity, this may allow patients
to require less medication, or perhaps be weaned from the necessity of
lifelong HAART, with its attendant challenges of treatment toxicities and
requirements for strict adherence."

    About MDX-010 and HIV

    CTLA-4 is believed to be an important molecule in regulating an immune
response. Expressed on CD4 and CD8 T cells, CTLA-4 is believed to be
responsible for suppressing the defensive activities of these T cells against
disease or infectious agents. In HIV-infected patients, where T cell response
is poor in controlling the virus, excess amounts of CTLA-4 have been found on
the T cells; this overexpression of CTLA-4 may facilitate susceptibility to
the HIV virus and contribute to the immune suppression found in AIDS patients.
Pre-clinical studies have shown that blocking CTLA-4 with an antibody can lead
to potent immune responses to various types of viruses, bacteria and cancer.

    MDX-010 is a fully human anti-CTLA-4 antibody. By blocking the suppressive
activity of CTLA-4 in HIV-infected patients, MDX-010 may enhance an anti-HIV
immune response and the ability to control HIV.

    According to the Centers for Disease Control, at the end of 2001 there
were 160,000 people in the U.S. living with HIV infection and 342,000 living
with AIDS.

    About MDX-010 and Cancer

    The use of MDX-010 to block CTLA-4 also has the potential to enable the
immune systems of cancer patients to more effectively fight tumors.  MDX-010
is currently in multiple Phase II clinical trials to test the product for use
in patients with melanoma and prostate cancer.  A webcast presentation
discussing the potential use of MDX-010 to treat cancer can be found at
www.medarex.com/Investor/Webcasts.htm.

    About Medarex

    Medarex is a biopharmaceutical company focused on the discovery and
development of therapeutics to treat life-threatening and debilitating
diseases. Medarex's UltiMAb Human Antibody Development System(SM) is a unique
combination of human antibody technologies that the Company believes enables
the rapid creation and development of fully human antibodies to a wide range
of potential disease targets for therapeutic antibody products, including
products for the treatment of cancer, inflammation, autoimmune and infectious
diseases.  Medarex's product pipeline is based on a variety of therapeutic
antibody products developed through the use of its UltiMAb technology.
Medarex creates and develops fully human antibodies for itself and others,
offering a full range of antibody related capabilities, including pre-clinical
and clinical development supported by cGMP manufacturing services.  For more
information about Medarex, visit its Web site at www.medarex.com.

    Except for the historical information presented herein, matters discussed
herein may constitute forward-looking statements that are subject to certain
risks and uncertainties that could cause actual results to differ materially
from any future results, performance or achievements expressed or implied by
such statements.  Statements that are not historical facts, including
statements preceded by, followed by, or that include the words "potential;"
"believes;" "anticipates;" "intends;" "plans;" "expects;" "estimates;"
"could;" "may;" or similar statements are forward-looking statements. Medarex
disclaims, however, any intent or obligation to update these forward-looking
statements. Risks and uncertainties include risks associated with product
discovery and development as well as risks detailed from time to time in
Medarex's public disclosure filings with the U.S. Securities and Exchange
Commission (SEC), including its Annual Report on Form 10-K for the fiscal year
ended December 31, 2002 and subsequent Quarterly Reports on Form 10-Q.  There
can be no assurance that such development efforts will succeed, that such
products will receive required regulatory clearance or that, even if such
regulatory clearance were received, such products would ultimately achieve
commercial success. Copies of Medarex's public disclosure filings are
available from its investor relations department.

    Medarex(R), the Medarex logo, UltiMAb(TM) and UltiMAb Human Antibody
Development System(SM) are trademarks and service marks of Medarex, Inc. All
rights are reserved.

SOURCE  Medarex, Inc.