A vaccine that could protect against cervical cancer has shown impressive efficacy in a Phase III trial, raising the hope that women could have access to effective prevention for the disease in as little as a year.

Merck & Co and partner Sanofi Pasteur MSD reported yesterday that the vaccine, called Gardasil, was 100% effective in the study in preventing the development of pre-cancerous cervical lesions that can develop into full-blown cervical cancer.

Gardasil is designed to protect against two forms of the human papillomavirus, types 16 and 18, which are spread by sexual contact. Together these two forms of HPV are responsible for 70% of all cervical cancers. It also contains antigens for two other strains, HPV 6 and 11, that cause genital warts.

Merck and Sanofi Pasteur now say they hope to file for approval of the vaccine before the end of the year in the USA, with a European submission occurring a little later, and this will nudge them ahead in the race to bring an effective HPV vaccine to market. Their main rival is GlaxoSmithKline, which said earlier this year it plans to file its HPV vaccine Cervarix in Europe during the first half of 2006, and in international markets over the remainder of the year [[01/07/05b]].

Analysts have suggested that the market for an effective HPV vaccination would be worth upwards of $4 billion dollars a year, although it remains to be seen which of the front-line candidates will garner the greatest share.

The latest study included 12,000 women, aged between 16 and 25 and enrolled at more than 90 clinical centres worldwide, who were not infected with either types 16 or 18 of the human papillomavirus at the start of the study. Half of them received three doses of Gardasil over a six-month period, while the remainder received a placebo.

After 17 months’ follow-up, all the women on Gardasil remained free of any signs of HPV lesions, while 21 of the women in the control group had developed pre-cancerous lesions or non-invasive cancer. Earlier studies have also shown that Gardasil can stimulate a protective immune response in females as young as 10, as well as in males, and so could be used to protect children before they become sexually active [[20/05/05a]].

Cervical cancer kills 274,000 women worldwide every year, including 33,000 in Europe.