Phase III study: GARDASIL prevents 77.5% of pre-cursor lesions to anal cancer

In a new phase III study, GARDASIL(R) (Quadrivalent Human Papillomavirus (Types 6, 11, 16 and 18) Recombinant Vaccine) prevented 77.5 per cent of anal intraepithelial neoplasia (AIN) associated with human papillomavirus (HPV) types 6, 11, 16 and 18 in 16-to-26 year-old men who have sex with men. The data are being presented on February 20, 2010 at the European Research Organization on Genital Infection and Neoplasia (EUROGIN) conference in Monte Carlo, Monaco.

"The quadrivalent HPV vaccine targets HPV types 6, 11, 16 and 18, which cause over 85% of anal cancers, as well as 90% of genital warts cases," said Dr. François Coutlée, professor at the University of Montreal, study investigator and Clinical Researcher at the Molecular Virology Laboratory, CHUM - Hôpital Notre-Dame. "Previous studies have shown the quadrivalent vaccine's efficacy in men against genital warts and now we have these results concerning anal cancer. This is encouraging, since HPV-related diseases are on the rise among men in North America."

GARDASIL(R) was approved for use in Canada in July 2006. GARDASIL(R) is indicated in girls and women 9 through 26 years of age for the prevention of infection caused by HPV types 6, 11, 16 and 18 and the following diseases associated with these types: cervical cancer, vulvar cancer, vaginal cancer, their precancerous lesions and genital warts. Currently, GARDASIL(R) is not indicated for use in boys and men in Canada.

GARDASIL prevented 77.5 per cent of pre-cursor lesions to anal cancer

The ability of the quadrivalent HPV vaccine (GARDASIL(R)) to prevent HPV 6, 11, 16 and 18-AIN and anal cancer in males was evaluated in a randomized, double-blind, placebo-controlled trial. A total of 598 16-to-26 year-old men who have sex with men received at least one dose of the quadrivalent HPV vaccine or placebo at the time of enrollment, and then again at two and six months.

This evaluation of efficacy of GARDASIL(R) against HPV-related anal disease was conducted in a population of men having sex with men because of the known high risk of anal infection that occurs in this group.

The study group included men who were not infected with the relevant HPV vaccine type at the start of the study, and who did not become infected with that HPV vaccine type during the course of the vaccination series (seronegative and HPV DNA-negative to the relevant HPV vaccine type at day one, and HPV DNA-negative through the vaccination series to month seven). The cases of the primary endpoint of AIN and anal cancer were counted starting after month seven with an average follow up of 2.5 years.

In this analysis, the quadrivalent HPV vaccine (GARDASIL(R)) prevented 77.5 percent (95 percent CI: 39.6, 93.3) of HPV 6, 11, 16, and 18-related AIN and anal cancer. A total of 29 men were diagnosed with HPV 6, 11, 16 or 18-related AIN during the study, with 24 cases in the placebo group and five in the vaccine group. No cases of HPV 11 or 18-related AIN were observed in the vaccine group. No cases of anal cancer were seen in either the placebo or vaccine group.

Administration of GARDASIL(R) was generally well tolerated in men 16-26 years of age. The proportion of subjects who reported serious adverse experiences or who discontinued due to an adverse experience was low and comparable between vaccination groups.

The burden of HPV-related anal cancer and genital warts

Three in four (75 per cent) sexually active Canadians will have at least one HPV infection in their lifetime. Most people who get HPV never develop any symptoms or health problems.

HPV types 16 and 18 cause approximately 90% of HPV-related anal cancers and their precursor lesions. In the year 2003-04, there were 491 new cases of anal cancer (203 in men, 288 in women) in Canada.

HPV types 6 and 11 cause 90% of genital warts cases. The lifetime risk of developing genital warts is approximately one in 10. In Canada in 2006, there were an estimated 41,450 new cases of genital warts in both men and women, with 48,600 ongoing cases at any one time.

Source: MERCK FROSST CANADA LTD.