The FDA has granted orphan drug status to Combretastatin A4P (CA4P) for the treatment of ovarian cancer, OXiGENE announced.

This is the second such designation for CA4P, a vascular disrupting agent that received orphan drug status for certain thyroid cancers in 2003. Early clinical trial results show a 67 percent response rate to a combination of CA4P and chemotherapy among women with advanced ovarian cancer who have previously failed cancer therapy, the company said.

Orphan drug designations, given to drugs that treat conditions affecting fewer that 200,000 people in the U.S., provide the manufacturer with tax credits, funding and a potentially a seven year market exclusivity.