FDA Advisory Committee Votes against Two Drugs for Prostate Cancer Prevention
An advisory committee to the Food and Drug Administration (FDA) has recommended against agency approval of two drugs for the prevention of prostate cancer. On December 1, the agency’s Oncologic Drugs Advisory Committee heard presentations about two large clinical trials, REDUCE and the NCI-supported PCPT, which found regular use of the drugs dutasteride (Avodart) and finasteride (Proscar), respectively, decreased the risk of prostate cancer in men undergoing regular prostate-specific antigen (PSA) screening and/or prostate biopsies. Both drugs are already FDA approved for the treatment of benign prostatic hyperplasia.
Based on the REDUCE results published in April, dutasteride’s manufacturer, GlaxoSmithKline, submitted a supplemental New Drug Application (NDA) to the FDA to market the drug for the reduction of prostate cancer risk. Although a similar NDA has not been submitted for finasteride, the committee was asked to vote on whether each drug had a favorable risk/benefit ratio for prostate cancer prevention in healthy men. In the case of finasteride, the claim was for prevention in men age 55 or older with a PSA of 3 ng/ml or less, and with dutasteride, the claim was for use in men with an elevated PSA but a previous biopsy that was negative for prostate cancer.
Much of the debate focused on the clinical significance of the cancers prevented by these drugs, as well as the concern that these agents may increase the risk of high-grade cancer, both of which were highlighted in a briefing document prepared by FDA staff. Dr. Ian Thompson of the University of Texas Health Science Center at San Antonio and the PCPT’s principal investigator presented follow-up analyses that suggested a substantial proportion of cancers prevented by finasteride are, in fact, clinically significant and the observed increase in high-grade disease was due, at least in part, to enhanced detection. Finasteride and dutasteride both shrink the prostate, making it easier to detect high-grade cancers with a needle biopsy.
The vote against finasteride was unanimous, while the vote against dutasteride was nearly unanimous. Although the FDA is not bound by the committee’s recommendations, in most cases the agency’s approval decisions are in line with advisory committee votes.