Shares of Spain's Zeltia wilted after U.S. regulators raised serious questions regarding its flagship cancer drug Yondelis.
While it's not unusual for regulators to concentrate on areas of concern, the staff review of Yondelis focused on key safety concerns that could pose a serious challenge to the developer when an FDA advisory panel gathers on Wednesday to review the data. Regulators saw added toxicity in an ovarian cancer study that combined Yondelis with another drug and asked if the benefit--a six-week delay in disease progression--was worth the added risk that it posed. Adding J&J's Doxil to docetaxel ended in a "markedly increased incidence and severity of a number of adverse events."
Staffers also questioned whether the data amply demonstrates the benefit, saying they would ask if the agency should wait for a final analysis of the survival benefit before extending an approval.
"This is really negative news for Zeltia if there are doubts over Yondelis for ovarian cancer... A lot of potential revenues are riding on FDA approval," a Madrid-based analyst tells Reuters. Zeltia won its first regulatory approval for ovarian cancer just a few days ago in the Philippines. Its shares dropped about 20 percent on the news of the FDA staffers' concerns.