By Debbie Strickland

Right on schedule, Medarex Inc. has launched its first Phase III trial, a 60-site study of an immunotoxin designed to prevent secondary cataracts.

The company gained the product, MDX-RA, earlier this year by buying Houston Biotechnology Inc., of The Woodlands, Texas, for $9.1 million.

MDX-RA is a monoclonal antibody linked to ricin, a plant-derived toxin. At the close of primary cataract surgery, the immunotoxin is delivered directly into the eye, where it binds to and destroys lens epithelial cells. Those cells can otherwise proliferate and lead to secondary cataracts.

In a placebo-controlled Phase I/II trial, the product achieved the primary endpoint by significantly reducing opacification.

The Phase III trial will enroll 680 patients over the course of nine to 12 months, with a two-year follow up. A new drug application filing could come as early as the end of 2000 or early 2001.

MDX-RA has a development and distribution partner in Japan, Santen Pharmaceuticals Co. Ltd., of Osaka. Medarex has exclusive rights to all other territories.

About half of primary cataract surgery patients will at some point develop secondary cataracts. According to the company, there is currently no method to predict or prevent the occurrence of secondary cataracts, which usually require neodymium-YAG laser surgery.

Medarex has four other clinical stage products: MDX-210, at the Phase II level in prostate, colon and renal cancer; MDX 447, in Phase I/II trials for head and neck cancer; MDX-33, an autoimmune drug that has completed Phase I trials and will soon enter Phase II; and MDX-22, a Phase II stage drug for acute myeloid leukemia.

A couple of the drugs are partnered with pharmaceutical firms: MDX-210, with Novartis AG, of Basel, Switzerland; and MDX-447, with Merck KGaA, of Darmstadt, Germany.

"We think MDX-210 will be moving towards Phase III in 1998, and that all of the products will be advancing their clinical status over the next year," reported Donald Drakeman, president and CEO. "We anticipate initiating clinical trials for one new cancer product and one new autoimmune product."

Medarex had $21.1 million as of Sept. 30, following a nine-month net loss of $2.7 million. *