Cervical Cancer Vaccine 100% Effective

In a phase III clinical trial involving more than 12,000 women, a new vaccine for the prevention of cervical cancer was found to prevent 100% of high-grade cervical pre-cancers and noninvasive cervical cancers associated with human papillomavirus (HPV).

The recombinant investigational vaccine, called Gardasil, was developed by Merck & Co. (Whitehouse Station, NJ, USA). The trial data were announced at the annual meeting of the Infectious Diseases Society of America (IDSA) in San Francisco (CA, USA) in October 2005. This trial is part of an ongoing program that involves more than 25,000 women in 33 countries worldwide.

In the phase III study, two vaccination groups were enrolled. Women aged 16-26, who were not infected with HPV 16 or 18 at enrollment, were randomized to receive a three-dose regimen of either Gardasil or placebo at day one, month 2, and month 6. A total of 6,082 women received Gardasil, while 6,075 received placebo. The trial evaluated the incidence of HPV 16/18 related cervical pre-cancers, known as CIN (cervical intraepithelial neoplasia) 2/3 and noninvasive cancers. CIN 2 is a moderate-grade lesion of the cervix, while CIN 3 represents both high-grade lesions and CIS (carcinoma in situ), the immediate precursor to invasive squamous cell cervical cancer. AIS (adenocarcinoma in situ) is the early development of adenocarcinoma (or glandular cancer) of the cervix. CIN 3 and AIS are defined as stage 0 cancer.

Analysis of the trial evaluated the incidence of CIN 2/3 and AIS in women who received three doses of Gardasil, had no major protocol violations, and remained free of HPV 16 and/or 18 through month seven. The analysis began 30 days after completion of the vaccination regimen and followed women for an average of 17 months. In this group, Gardasil prevented 100% of cases of CIN 2/3 or AIS associated with HPV types 16 and 18. No cases of CIN 2/3 or AIS were observed in the vaccine group, compared to 21 cases in the placebo group. Gardasil is designed to target HPV types 16 and 18, which account for 70% of cervical cancers, and HPV types 6 and 11, which account for 90% of genital warts.

"Merck has been committed to vaccine research and development for over a century,” observed Peter S. Kim, Ph.D., president, Merck Research Laboratories. "We have hope that Gardasil will continue the great Merck tradition of developing medicines and vaccines that make a real difference in people's lives.”




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