Dendreon Corp., maker of the prostate cancer drug Provenge, fell 7 percent after Johnson & Johnson said its rival product, Zytiga, performed better than a placebo in a trial.
Dendreon dropped to $10.12 at the close of New York trading, its biggest one-day decline since Feb. 27.
An independent monitoring committee recommended halting the study on Zytiga, made by New Brunswick, New Jersey-based J&J, after an interim analysis showed patients taking it were less likely to die or have the cancer worsen. All the patients, who hadn’t yet started chemotherapy, should be switched to Zytiga, the safety board said. The results may make Zytiga more of a threat to Seattle-based Dendreon’s Provenge, wrote Joseph Pantginis, from Roth Capital Partners, in a note to today.
“This news represents a major, at least, headline blow to the Provenge franchise,” Pantginis wrote. “Expansion of Zytiga’s label, which currently includes post-chemotherapy castrate resistant prostate cancer patients, may be perceived as a significant threat to Provenge’s market share.”
Zytiga blocks an enzyme called CYP17 that helps make androgen, the hormone that fuels prostate cancer. Medivation Inc. and Takeda Pharmaceutical Co. are developing similar drugs. Eventually, men with spreading prostate cancer may rely on a mixture of the medications to stop the tumors, analysts said.
Johnson & Johnson plans to file Zytiga for Food and Drug Administration approval in the second half of 2012 for men who haven’t yet received chemotherapy, the same group now approved for Dendreon’s Provenge.
Medivation rose 14 percent to $72.91, while J&J gained less than 1 percent to $64.85 in New York trading.