Gardasil (quadrivalent human papillomavirus types 6, 11, 16, 18, recombinant vaccine), an investigational vaccine from Merck & Co Inc. prevented 100 per cent of high-grade cervical pre-cancers and non-invasive cervical cancers associated with human papillomavirus (HPV) types 16 and 18 in a new phase III study.

The analysis compared Gardasil to placebo in women who were not infected with HPV 16 and 18 at enrollment and who remained free of infection through the completion of the vaccination regimen. The data will be presented for the first time at the Infectious Diseases Society of America (IDSA) annual meeting, claims a company release.

This trial is part of the ongoing phase III programme for Gardasil, which involves over 25,000 people in 33 countries worldwide. Merck remains on track to submit a biologics license application for Gardasil to the Food and Drug Administration in the fourth quarter of 2005.

"These are the first pivotal data to show that vaccination with Gardasil reduced HPV 16 and18-related cervical pre-cancer and non-invasive cervical cancer," said Laura Koutsky, principal investigator, HPV research group, University of Washington, Seattle.

Gardasil was designed to target HPV types 16 and 18, which account for 70 per cent of cervical cancers, and HPV types 6 and 11, which account for 90 per cent of cases of genital warts. These four types also cause benign cervical changes that result in abnormal Pap tests.