Merck's Investigational HPV-Vaccine Reduced Infection in Clinical Study

Gardasil, the investigational vaccine against human papillomavirus (HPV) from Merck, has been found to significantly reduce the combined incidence of persistent HPV 6, 11, 16, or 18 infection and related diseases, including new cervical pre-cancers and genital warts compared to placebo in a Phase II study published for the first time in The Lancet Oncology.

This Phase II, randomized, double-blind, placebo-controlled study evaluated the efficacy of Gardasil in preventing infection from the types of HPV responsible for 70 percent of all cases of cervical cancer and 90 percent of all cases of genital warts. In the study, 552 women in the U.S., Europe and Brazil between the ages of 16 and 23 were randomized to receive vaccine or placebo at Day 1, Month 2, and Month 6.

The primary endpoint of the study was to assess the efficacy of the investigational vaccine in reducing the combined incidence of persistent HPV 6, 11, 16, and 18 infections and related diseases, including cervical pre-cancers (cervical intraepithelial neoplasia, or CIN), cervical cancer, and/or external genital lesions (genital warts).

Over the two and a half years of follow-up after vaccination, Gardasil reduced the combined incidence of persistent infection from HPV 6, 11, 16, or 18 and related genital disease including new cervical pre-cancers and genital warts by 90 percent compared with placebo among women who were naive to the relevant HPV types at baseline (p<0.001).

Thirty-six cases of either disease, persistent infection, or detection of HPV on the last visit on record were seen in the placebo group compared to four in the group who received Gardasil. Of the four cases seen in the group who received Gardasil, one was confirmed as persistent infection; in the other three cases HPV was detected on the last study visit but was not later confirmed as a persistent infection.