The Gardasil vaccine protected most young women from cervical cancer and homosexual men from anal cancer, according to new studies released Wednesday by its maker, Merck&Co.
The vaccine is designed to block four of the most common strains of the sexually transmitted human papilloma virus, or HPV. Two of those HPV strains cause the majority of cases of cervical cancer and anal cancer, and the other two can cause genital warts.
Gardasil, Merck's top-selling vaccine, already is approved for prevention of cervical cancer and genital warts in girls and women aged 9 to 26. It's also approved for preventing genital warts in boys and men aged 9 to 26.
Data from the new studies will be used to seek approval from the Food and Drug Administration to also market Gardasil for preventing cervical cancer and genital warts in women up to age 45 and for preventing anal cancer in males.
Merck, which is based in Whitehouse Station, N.J., funded both studies.
The women's study found three injections of the vaccine over six months prevented precancerous lesions on the cervix, as well as genital warts and persistent infections of HPV, in about 89 percent of the participants, compared to women in a group that got three dummy shots. Altogether, 23 women getting dummy shots and one getting the vaccine developed lesions or warts. That study included 3,819 24- to 45-year-old women, in multiple countries, who did not have cervical disease, genital warts or an HPV infection, which the immune system often eliminates over time. The women were examined periodically for about four years on average.
The second study found three injections of the vaccine prevented anal cancer and precancerous lesions of the anus in about 77 percent of young men, compared with those in a group getting dummy shots. No men in either group developed anal cancer, but 24 who got dummy shots and five who got the vaccine developed precancerous lesions. The men were studied for three years on average, starting with the first dose.
The results were released early Wednesday, in conjunction with their presentation at a European conference of doctors and researchers specializing in cancer and genital infections.
Merck submitted more detailed data from the women's study to the FDA late in 2009 and expects a ruling by June on whether it may market Gardasil for women aged 27 to 45. The regulatory agency previously turned Merck down, asking for longer-term follow-up on the women; this study followed them for an additional year and a half.
The company plans to submit the data on anal cancer in men to the FDA and apply for approval to market the vaccine for that use at some point, said Merck spokeswoman Pam Eisele.
Gardasil, one of Merck's 10 best-selling products, had sales totaling $1.12 billion in 2009.
Side effects of the vaccine include dizziness and fainting, nausea and vomiting, fever, headache and pain, swelling and itching at the injection site. Gardasil cannot be given to women who are pregnant or anyone with a severe allergy to yeast.