Clarifying the Issues Surrounding Dendreon’s Provenge
Posted on Apr 16th, 2007 with stocks: DNDN
Wall Diver submits: Rebuttal to article, “Dendreon’s Provenge Apart by ODAC Member”:
On April 13, 2007, in Volume 33, No. 14 of The Cancer Letter, a letter was published which the Editor, Paul Goldberg, attributed to Howard Scher, MD, of the Memorial Sloan-Kettering Cancer Center. In this letter, the author warned the FDA about flaws in the Provenge (Sipuleucel-T) trial data (sponsor, Dendreon Corporation (DNDN); this, while the FDA decision about Provenge approval is pending.
Dr. Scher served as a member of the Cellular, Tissue and Gene Therapy Advisory Committee (CTGTAC), which, on March 29, 2007, voted positively on the FDA questions placed before it. The Advisory Committee efficacy vote was 13-4 in favor of Sipuleucel-T; Dr. Scher was among the four committee members who voted in disapproval on that point. The Advisory Committee safety vote was a unanimous 17-0.
In Dr. Scher’s letter, there were a number of questionable, or debatable, assertions, and a number of seeming logical flaws and contradictions, to the extent that it seems possible that he was not the actual author of this letter. However, for the sake of discussion, the authorship attribution by The Cancer Letter is considered to be factual. This response to Dr. Scher’s purported letter is an attempt to address some of those items, both to clarify the issues, and to encourage debate about them.
In addressing his efficacy concerns, Dr. Scher reportedly stated:
My vote was based on the fact that neither of the two trials presented met their primary endpoint, which renders the significance of results from any subsequent analyses as “exploratory†and “hypothesis generating.†As such, the results do not constitute “proof†of benefit or justify a conclusi