Medarex Announces Allowance of Investigational New Drug Application for Wholly-Owned...

Medarex Announces Allowance of Investigational New Drug Application for
Wholly-Owned Fully Human Anti-CXCR4 Antibody, MDX-1338

-Clinical study planned for relapsed / refractory acute myelogenous leukemia-

PRINCETON, N.J., May 27 /PRNewswire-FirstCall/ -- Medarex, Inc. (Nasdaq: MEDX)
announced today the allowance of an investigational new drug application (IND)
filed with the U.S. Food & Drug Administration (FDA) for MDX-1338, for the
treatment of patients with acute myelogenous leukemia (AML). MDX-1338 is a
fully human antibody that targets CXCR4, a chemokine receptor found on the
surface of many cancer cells, including certain leukemias, lymphomas and other
cancers. Preclinical laboratory experiments have shown that MDX-1338 can block
the growth of, and even directly kill, selected human tumor cells.

The Phase 1, open-label, multicenter, dose-escalation study of MDX-1338 as a
monotherapy and in combination with chemotherapy is expected to enroll up to
34 patients with relapsed/ refractory AML. This trial is designed to establish
and evaluate the safety, tolerability and maximum tolerated dose, as well as
preliminary pharmacodynamics and efficacy of MDX-1338.

"We are pleased that MDX-1338 has progressed into the clinic, representing our
eighth development candidate in oncology and further enhancing our focus on
oncology/immunology therapeutic indications," said Howard H. Pien, Chairman
and CEO of Medarex. "We believe that MDX-1338 could have potential activity in
multiple cancers. Our first Phase 1 study will be conducted in AML and future
studies are expected to target a variety of other leukemias and solid tumors
and may involve monotherapy and combination therapy."

The American Cancer Society estimates that in 2008, approximately 13,290
patients in the United States will be diagnosed with AML.

About Medarex
Medarex is a biopharmaceutical company focused on the discovery, development
and potential commercialization of fully human antibody-based therapeutics to
treat life-threatening and debilitating diseases, including cancer,
inflammation, autoimmune disorders and infectious diseases. Medarex applies
its UltiMAb(R) technology, product development and clinical manufacturing
experience to generate, support and potentially commercialize a broad range of
fully human antibody product candidates for itself and its partners. Over
forty of these therapeutic product candidates derived from Medarex technology
are in human clinical testing or have had INDs submitted for such trials, with
the most advanced product candidates currently approved for commercial sale,
the subject of regulatory applications for marketing authorization or in Phase
3 clinical trials. Medarex is committed to building value by developing a
diverse pipeline of antibody products to address the world's unmet healthcare
needs. For more information about Medarex, visit its website at
www.medarex.com.

Medarex Statement on Cautionary Factors
Except for the historical information presented herein, the statements
relating to MDX-1338 in this press release may constitute forward-looking
statements, as defined in the Private Securities Litigation Reform Act of
1995, 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. Medarex disclaims,
however, any intent or obligation to update these forward-looking statements.
Risks and uncertainties include risks associated with product discovery and
development of MDX-1338, 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, 2008 and its quarterly reports on Form 10-Q. There can be
no assurance that such development efforts will succeed or that developed
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 and UltiMAb(R) are registered trademarks of
Medarex, Inc. All rights are reserved.

SOURCE Medarex, Inc.

Laura S. Choi, Investor Relations, +1-609-430-2880, x2216; or Nichol Ochsner,
Corporate Communications (media), +1-609-430-2880, x2214