In late-stage testing, Gardasil, a human papillomavirus (HPV) vaccine, was 100 percent effective at preventing infection with four HPV types known to be associated with cervical cancer.
HPV causes cervical cancer. There are over 500,000 cases of cervical cancer diagnosed worldwide, and of those 300,000 women die annually. The lifetime risk around the world of a woman developing cervical cancer is about 70 percent.
Gardasil “offers implications for affecting women’s health care tremendously by preventing cervical cancer and other HPV-related diseases,” said Dr. Diane M. Harper from Dartmouth Medical School in Lebanon, New Hampshire.
Based on these data, Merck submitted Gardasil to the US Food and Drug Association for approval on December 1st.
“In addition to cervical cancer, HPV causes vaginal cancer, vulvar cancer and anal cancers, which are on the increase,” Harper noted, adding that therapy is “pretty effective, but not 100 percent, and there are recurrences.”
HPV 16 and 18 are responsible for about 70 percent of all anal/genital cancers in women. About 25 percent of low-grade lesions and most genital warts are caused by HPV types 6 and 11.
At the 45th Interscience Conference on Antimicrobial Agents and Chemotherapy underway in Washington, D.C., Harper presented the results of the vaccine’s efficacy against types 6, 11, 16 and 18, which are implicated in the whole spectrum of HPV diseases in women.
In the trial, 5,000 women, ages 16 to 24 at over 62 sites from 16 nations, received three vaccines throughout the year. The women who were free of HPV at entry underwent complete genital examinations, six Pap smears and had blood drawn at five different times.
Of the 93 percent of women who received all three vaccinations, “there were no cases in the vaccine group of women developing any 6,- 11,- 16-, 18-related cervical lesions, whereas there were 37 in the placebo group. This gives us a 100 percent efficacy,” Harper said.
“For vulvar/vaginal lesions, there were 40 cases in the placebo group, and in the vaccine group - zero,” she continued, “again giving us 100 percent efficacy.”
When all of the women in the study were included in the analysis - including those who were not compliant to the protocol or did not receive the full vaccine course, reflecting “real life utilization,” the efficacy rate was 97 percent.
The worst side effect was redness and swelling at the injection site, affecting 88 percent in the Gardasil group and 80 percent in the placebo group, a statistically significant difference.
“This vaccine is safe, it’s tolerable and it’s 100 percent effective, when given in the three doses in the protocol,” Harper concluded.
Revision date: July 7, 2011
Last revised: by Sebastian Scheller, MD, ScD