COPENHAGEN, Denmark; May 17, 1999 - Genmab A/S announced today that it has obtained exclusive rights to patents to develop antibodies against IL15, a cytokine implicated in a variety of inflammatory conditions including arthritis, psoriasis and inflammatory bowel disease. Genmab is developing a portfolio of fully human antibodies derived from Medarex's (Nasdaq: MEDX) HuMAb-Mouse™ technology.

These rights were obtained from Immunex Corporation (Nasdaq: IMNX) through a sub-license from Medarex. Immunex retains an option to commercialize the resulting fully human IL15 antibody and, in that event would provide a license fee, milestone payments and profit sharing to Genmab. If Genmab commercializes the IL15 antibody, it would pay Immunex milestone fees and royalties. Immunex will also provide scientific and technical assistance to Genmab with respect to IL15. Immunex has retained its rights to IL15 for therapeutic and diagnostic purposes.

In a separate transaction not involving Immunex, Genmab has also increased its capital resources as a result of an additional $2 million investment by current shareholders, led by BankInvest Biomedical Development Fund. At the same time, Genmab has received a license to an additional target from Medarex, in exchange for equity, and will use the additional capital to expand product development activities.

"A human antibody against IL15 has the potential to treat diseases that affect millions of people," said Lisa N. Drakeman, Ph.D., Chief Executive Officer of Genmab. "We look forward to moving this product into clinical trials."

Immunex is a biopharmaceutical company dedicated to developing immune system science to protect human health. The company's products offer hope to patients with cancer, inflammatory and infectious diseases.