Medarex, Inc. (Nasdaq: MEDX) today presented preclinical data demonstrating potent anti- tumor activity from two separate studies exploring the efficacy and safety in animal models of anti-CD19 and anti-CD70 antibody-drug conjugates. CD19 and CD70 are both attractive targets for an antibody-drug conjugate approach to cancer therapy. They are expressed on cancer cells with limited normal patterns of expression and are rapidly internalized when bound to antibody. Data from the studies were presented at the American Association for Cancer Research (AACR) annual meeting, April 14-18, 2007, in Los Angeles, CA.

Efficacy study of anti-CD19 antibody drug conjugates in Raji tumor xenograft and systemic model (Abstract #4104)

CD19 is expressed on B cell cancers, including non-Hodgkin's lymphoma, chronic lymphocytic leukemia and acute lymphocytic leukemia. Single dose treatments of a fully human anti-CD19 antibody drug conjugate demonstrated in vivo anti-tumor efficacy leading to the regression of established subcutaneous tumors and systemic tumors in leukemia xenograft models. Anti-CD19 antibody- drug conjugate was well-tolerated and without toxicity in the animal models.

Single, low dose treatment of lymphoma and renal cancer xenografts with human anti-CD70 antibody toxin conjugates, results in long term cures (Abstract #4112)

CD70 is highly expressed in multiple tumor types, including many lymphomas and clear cell renal cancer. Single, low dose treatments of a fully human anti-CD70 antibody drug conjugate demonstrated in vivo anti-tumor efficacy in both preclinical lymphoma and renal cancer xenograft animal models. The anti- CD70 antibody drug conjugate demonstrated a high specificity for its target, a wide therapeutic window of activity, and a favorable toxicity and safety profiles in larger animals at dose levels which are in excess of an efficacious dose determined in the xenograft models.

"Antibody-drug conjugates exploit the specificity of antibodies and the potency of cytotoxic agents to destroy cancer cells," said Nils Lonberg, PhD, Senior Vice President and Science Director at Medarex. "We believe that the anti-tumor activity from these preclinical antibody-drug conjugate studies is quite compelling, and we look forward to fully exploring the safety and therapeutic activity and application of these programs in future clinical trials."

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 and 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. More than 30 of these therapeutic product candidates derived from Medarex technology are in human clinical testing or have had INDs submitted for such trials, with six of the most advanced product candidates currently 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 medarex.

Medarex Statement on Cautionary Factors

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 development, risks that favorable efficacy and safety results in animal models will not be replicated in humans, unforeseen safety issues resulting from the administration of antibody products in humans, 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, 2006. 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.

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