Genentech Inc. on Friday said it has begun Phase I clinical trialsof a monoclonal antibody (MAb) to treat 20 patients withbreast and ovarian cancers.

The trial at the UCLA School of Medicine is the South SanFrancisco, Calif., company's first foray into MAb therapeutics,said Genentech spokeswoman Susan Rogers. MAbs areantibodies that recognize and bind to a single site on a foreignsubstance.

Genentech's MAb is targeted against the HER-2 protein, whichcauses a particularly virulent form of cancer that respondspoorly to traditional therapies. The MAb binds to a receptor onthe protein, preventing it from causing the unchecked growthof tumor cells.

Healthy people have a single copy of the HER-2 oncogene,which produces HER-2 protein. But about one-third of cancerpatients have between 20 and 40 extra copies of the gene.These patients produce 50 to 100 times the normal amount ofHER-2 protein, resulting in an aggressive form of cancer.

Breast cancer is the most common form of cancer amongwomen, with an estimated 150,000 new cases annually, and issecond only to lung cancer as a cause of death. Ovarian canceris the fifth most common cancer among women and is fatal in62 percent of cases.

MAbs derived from mice, such as the one Genentech is using,have proven disappointing in human trials to date. Genentechis working on a "humanized" MAb that combines elements ofthe mouse antibody with human immunoglobulin-G. Genentechhopes to have this second-generation MAb within a year, andmay use it in Phase II efficacy trials.

-- Karen Bernstein BioWorld Staff

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