The vaccine, manufactured by Merck & Co. Inc., is approved for the prevention of cervical, vulvar, and vaginal cancers and precancerous lesions in females aged 9-26 years, and for the prevention of genital warts in males and females aged 9-26 years. The company is seeking an indication for the prevention of anal cancer in males and females aged 9-26 years.
Previous studies have shown that anal cancer and cervical cancer are biologically similar, and both are associated with HPV infections, Dr. Joel Palefsky, professor of medicine at the University of California, San Francisco, said at the meeting.
The primary data supporting an anal cancer indication for Gardasil came from a randomized, controlled trial of 602 men who have sex with men (MSM), who were part of the larger study that led to the indication for preventing genital warts in boys and men. The participants received three doses of vaccine or a placebo.
The vaccine showed 78% effectiveness, compared with placebo in preventing anal intraepithelial neoplasms related to human papillomavirus types 6, 11, 16, and 18. These lesions are considered precursors to anal cancer, Dr. Palefsky said.
Although MSM are at increased risk for HPV-associated anal cancer, they are not the only population at risk. Data from the National Cancer Institute presented at the meeting showed that anal cancer incidence in the United States is increasing by a rate of approximately 2% per year, and that approximately 60% of cases and deaths occur in women. 
A majority of the committee members expressed opinions in favor of the indication, but no formal vote was taken. The FDA will consider the committee’s recommendations. If the indication is approved before the February 2011 meeting of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, the ACIP might revisit its previous recommendation against routine HPV vaccination for boys and men for genital wart prevention. ACIP has given a permissive recommendation for HPV vaccination for boys and men aged 9-26 years at the discretion of the physician.
Dr. Palefsky has served as a consultant and clinical investigator for Merck & Co. Inc.
