FDA will accept interim data for prostate cancer immunotherapy license

Dendreon Corp. said it has received confirmation that the FDA will accept either a positive interim or final analysis of survival from its ongoing IMPACT (Immunotherapy for Prostate AdenoCarcinoma Treatment) study to amend the biologics license application (BLA) for sipuleucel-T (Provenge), a form of immunotherapy in late-stage development for the treatment of hormone-refractory prostate cancer.

The information was obtained in a recent follow-up meeting with the FDA to discuss the additional clinical data required to support the licensure of the drug requested by the FDA in a complete response letter that Dendreon received on May 8.

"We anticipate completing enrollment in the IMPACT study this year and interim survival results in 2008," said Mitchell H. Gold, MD, of Dendreon. "We are committed to making Provenge available as rapidly as possible to help the many men with late-stage prostate cancer who currently have few appealing treatment options."

The approval process for sipuleucel-T has been surrounded by controversy in recent weeks. The FDA’s complete response ("approvable") letter coincided with an FDA request for additional clinical data in support of the efficacy claim contained in the BLA, effectively delaying the drug’s approval.

A patient advocacy group known as ProvengeNow vowed to fight the ruling, and about 100 members rallied in Washington earlier this week to petition Congress and pressure the FDA to approve sipuleucel-T while Dendreon completes the IMPACT study.

Meanwhile, the New York Times reported that two leading prostate cancer experts received threats for opposing approval of the drug. Howard Scher, MD, of Memorial Sloan-Kettering Cancer Center in New York, and Maha Hussain, MD, of the University of Michigan, Ann Arbor, who both served on the FDA advisory committee examining sipuleucel-T, were protected by bodyguards during the recently concluded American Society of Clinical Oncology annual meeting in Chicago, the newspaper reported.