Medarex Announces Phase I Clinical Trial of MDX-1100, a Fully Human Anti-IP10 Antibody, for the Treatment of Ulcerative Colitis

PRINCETON, N.J., May 11 /PRNewswire-FirstCall/ — Medarex, Inc. today announced the allowance of an Investigational New Drug (IND) application filed with the U.S. Food and Drug Administration (FDA) to initiate a Phase I clinical trial for MDX-1100, a fully human monoclonal antibody that targets IP-10 (also known as CXCL10), for the treatment of ulcerative colitis. IP-10 is a chemokine that that is associated with the pathogenesis of multiple inflammatory diseases, including ulcerative colitis.

The multi-center, single-dose, dose-escalation Phase I clinical trial is expected to enroll up to 32 patients with ulcerative colitis. The trial is designed to collect safety and initial efficacy data. Subject to patient enrollment, data from the Phase I clinical trial is expected in the second half of 2006.

“We are pleased to see MDX-1100, the twenty-third UltiMAb(R)-derived antibody product candidate, enter into the clinic,” said Donald L. Drakeman, President and CEO of Medarex. “We believe that by targeting IP-10, MDX-1100 has the broad potential to address multiple autoimmune and inflammatory diseases.”

About MDX-1100

MDX-1100 is a fully human antibody that is designed to target IP-10 (also known as CXCL10), a chemokine involved in the migration of activated T cells and monocytes into sites of inflammation and associated with multiple autoimmune disorders and inflammatory diseases such as rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease. Preclinical studies demonstrate that antibodies targeting IP-10 neutralize the effects of IP-10 and attenuate disease progression in animal models of ulcerative colitis and inflammatory bowel disease, as well as multiple sclerosis and rheumatoid arthritis.

Medarex acquired full rights to MDX-1100 as part of its acquisition of Ability Biomedical Corporation in August 2004.

About Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of the colon and is characterized by inflammation and ulceration of the colon’s innermost lining. Symptoms typically include bloody diarrhea and abdominal pain. According to the Crohn’s & Colitis Foundation of America, it is estimated that there are up to approximately 500,000 Americans with ulcerative colitis.

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 technology and product development and clinical manufacturing experience to generate, support and potentially commercialize a broad range of fully human antibody products for itself and its partners. Twenty-three of these therapeutic products derived from Medarex technology are currently in human clinical testing, with two of the most advanced products presently in Phase III 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 http://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”; “believe”; “anticipate”; “intend”; “plan”; “expect”; “estimate”; “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, uncertainties related to the outcome of clinical trials, slower than expected rates of patient recruitment, unforeseen safety issues resulting from the administration of MDX-1100 in patients, uncertainties related to product manufacturing 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, 2004 and subsequent Quarterly Reports on Form 10-Q. There can be no assurance that such development efforts will succeed or that other 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.

Medarex, Inc.

CONTACT: Laura S. Choi, Investor Relations, +1-609-430-2880, x2216, orJean Mantuano, Corporate Communications (media), +1-609-430-2880, x2221, bothof Medarex, Inc.

Web site: http://www.medarex.com/

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