December 3, 1998
Source: Medarex, Inc

Medarex's HER-2 Product Shows Anti-Cancer Activity In Additional Phase II Prostate Studies
ANNANDALE, N.J., Dec. 3 /WiredBird/ -- Medarex, Inc. (Nasdaq: MEDX) announced today that continuing Phase II clinical trials involving its anti-HER-2 cancer product MDX-210 have shown improvements in PSA levels and quality of life in a second group of late stage prostate cancer patients who had failed all standard treatments.

Thirteen of 20 hormone refractory prostate cancer patients (65%) experienced a reduction of serum levels of PSA, a biochemical marker associated with disease progression and death. Seven of the patients (35%) had PSA reductions of 50% to 99%. In some cases, the PSA levels have been reduced for greater than 150 days. Additionally, 27% of patients evaluable for quality of life reported a significant reduction in average pain levels following treatment with MDX-210. Intense debilitating bone pain frequently accompanies advanced prostate cancer following spread of the cancer cells to the bones.

This Phase II study incorporates a revised dosing schedule compared to the one used in the initial Phase II trial, the results of which were reported at the American Society for Clinical Oncology Meeting in May 1998. The earlier results showed that 9 of 22 hormone refractory prostate cancer patients experienced a drop in PSA levels.

"Sixty-five percent of these patients had a reduction of PSA levels, which may correlate with a lower risk of imminent death according to a recent study," said Nicholas James, M.D., Ph.D., Principal Investigator for the Phase II clinical trials.

MDX-210 is a Bispecific antibody that targets the HER-2 receptor. HER-2 is a protein found in excess on the surface of certain cancer cells, including prostate, kidney, colon and breast. Bispecific antibodies are Target-Trigger combinations. One arm of the Bispecific activates and guides immune system killer cells, and the other targets the disease cells.

Patients in both groups were pre-treated with GM-CSF (granulocyte monocyte-colony stimulating factor) which increases production and differentiation of certain white blood cells, such as granulocytes, monocytes, macrophages, and eosinophils. This was followed by administration of the anti-cancer Bispecific antibody MDX-210, which is designed to trigger the killing function of immune cells against the targeted cancer cells.

These results were presented at the 1998 International Antibody Engineering Conference in San Diego by Jan van de Winkel, Ph.D., Vice President and Scientific Director of Medarex Europe and Professor of Immunology, Utrecht University.

Medarex is a biopharmaceutical company developing monoclonal antibody-based therapeutics to fight cancer and other life-threatening and debilitating diseases. The Company has developed a broad platform of patented technologies for antibody discovery and development, including the HuMAb-Mouse(TM) system for the creation of high-affinity human antibodies; Bispecific antibodies, which enhance and direct the body's own immune system to fight disease; and immunotoxin technology. Medarex has six products in clinical development for the treatment of cancers and leukemia, autoimmune diseases and ophthalmic conditions. For more information about the Company visit its web site at http://www.medarex.com.

Certain statements in this press release consist of forward-looking statements that involve risks and uncertainties including, but not limited to, uncertainties regarding the progress of on-going clinical trials and the continuation of business partnerships. Actual results, events or performance may differ materially.

SOURCE Medarex, Inc.
Web site: http://www.medarex.com
CONTACT: Donald L. Drakeman, President and CEO of Medarex, Inc.,908-713-6001, or Kimberly Hofman of Middleberg + Associates,212-888-6610, ext. 544, for Medarex, Inc.