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HPV Vaccine Prevents HPV Lesions and Infection in Men
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XVIII International AIDS Conference, July 18-23, 2010, Vienna
Mark Mascolini
A human papillomavirus (HPV) vaccine designed to protect against four strains of HPV prevented external HPV lesions and new HPV infection in a placebo-controlled trial that enrolled more than 4600 heterosexual and gay men [1].
Infection with HPV, a sexually transmitted virus, may lead to anal, penile, and other cancers in men. An HPV vaccine is licensed to prevent cervical cancer in women and is recommended by the Centers for Disease Control for girls before they become sexually active and exposed to HPV [2]. This is the first trial of an HPV vaccine in men.
Researchers in 18 countries enrolled 4065 healthy men, including 3463 heterosexuals from 16 to 23 years old and 602 gay men from 16 to 26. The investigators randomized them to receive three shots of a quadrivalent HPV vaccine aimed at genotypes 6, 11, 16, 18 (Gardasil) or to receive placebo shots. Neither the men nor their physicians knew whether study participants were getting placebo or the vaccine. The study's primary endpoint was reduced incidence of new HPV-related external genital lesions in a per-protocol analysis and an intention-to-treat analysis.
Men were eligible for the study if they had no evidence of genital lesions and no history of genital warts, and if they had 1 to 5 lifetime sexual partners. The per-protocol analysis included men who were seronegative for the four HPV types on day 1 and PCR negative for the four HPV types through March 7, who received all three vaccinations at the correct time, and who did not deviate from the study protocol.
In the per-protocol analysis, HPV-related external genital lesions arose in 3 men receiving the vaccine and 31 receiving placebo. Those numbers translated into an observed efficacy of 90.4% for the vaccine (95% confidence interval [CI] 69.2 to 98.1). Most lesions were condylomata acuminata, a type of genital wart. No cases of penile, perianal, or intraepithelial neoplasia developed in any man getting the HPV vaccine.
No one got anal cancer during the study. In the per-protocol analysis, anal intraepithelial neoplasia (a prelude to anal cancer) developed in 5 vaccinated men and 24 men receiving placebo for an efficacy of 77.5% (95% CI 39.6 to 93.3, P < 0.001). In the intention-to-treat analysis, the vaccine had an observed efficacy of 65.5% (95% CI 45.8 to 78.6) against external genital lesions. Efficacy against persistent infection was 85.5% (97.5% CI 73.4 to 92.9) in the per-protocol analysis and 47.8% (95% CI 36.0 to 57.6) in the intention-to-treat analysis. Efficacy against HPV DNA detection was 44.7% (95% CI 31.5 to 55.6) in the per-protocol analysis and 27.1% (95% CI 16.6 to 36.3) in the intention-to-treat analysis.
Study participants generally tolerated the vaccine well, although injection site pain occurred significantly more often with the vaccine than with placebo (57% versus 51%, P < 0.001). No serious adverse events occurred in the vaccine group or the placebo group. Rates of systemic adverse experiences were 14.1% with the vaccine and 14.6% with placebo.
Another study is planned for a vaccine designed to protect against nine types of HPV.
References
1. Jessen H, Giuliano A, Palefsky J, et al. Quadrivalent HPV vaccine efficacy against HPV 6/11/16/18 infection and disease in men. XVIII International AIDS Conference. July 18-23, 2010. Vienna. Abstract THLBB101.
2. Centers for Disease Control and Prevention. HPV vaccine information for clinicians. Last modified June 26, 2008.
http://www.cdc.gov/std/hpv/STDFact-HPV-vaccine-hcp.htm#vaccrec
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