In a race to market the first vaccine against the virus that causes cervical cancer and genital warts drug manufacturers Merck & Co Inc. and GlaxoSmithKline plc are in head-to-head competition.
The pioneering vaccine could dramatically reduce the incidence of cervical cancer and researchers say it is also effective against genital warts, a sexually-transmitted infection affecting 1 per cent to 2 per cent of adults.
The vaccine, made from a non-infectious virus-like particle, is also said to be 100 per cent effective at preventing the appearance of pre-cancerous cells. After 277 women were given the vaccine overall rates of persistent infection and disease both fell by 90 per cent.
Merck's vaccine, Gardasil, is in direct competition with Cervarix, the vaccine produced by UK-based GlaxoSmithKline plc. Both protect against the two strains of human papillomavirus (HPV) responsible for 70 per cent of cervical cancers.
Gardasil protects against two further strains that cause genital warts and the new results mean that Gardasil could be on the market within two years. A final-stage trial involving more than 25,000 participants worldwide is underway and should yield data later this year.
The vaccine which wins the race is set to become one of the biggest-selling drugs of all time. Not only would it prevent cervical cancer, but it would mark a medical milestone by being the first anti-cancer vaccine prescribed to non-trial patients.
Cervical cancer affects some 470,000 women a year, and survival chances are good if the disease is detected and treated early.
Most deaths occur in the developing world where there are no organised screening programmes but each year in Europe and the United States about 35,000 women die from cervical cancer The Phase II trial led by Dr Luisa Villa from the Ludwig Institute for Cancer Research in Brazil, tested the effectiveness of Gardasil on 277 healthy women aged 16 to 23, another 275 women were randomly assigned to a dummy "placebo" treatment. The women, from Brazil, Europe and the USA, were not pregnant, had no previous abnormal cervical smears, and reported a history of four or fewer partners.
The women received three injections of the vaccine over a period of six months and were monitored for three years undergoing regular gynaecological examinations.
Cervical cancer is caused by HPV strains 16 and 18, and genital warts by strains six and 11. Combined incidence of persistent infection or disease from all four strains fell by 90 per cent in women given the vaccine and the vaccine was also 100 per cent effective at preventing the abnormalities that precede cervical cancer.
In the trial 36 cases of either disease, persistent infection or detection of HPV on a last recorded visit occurred in the placebo group, compared with four in the vaccine group. The researchers say that HPV vaccination would be most effective if given to 10 to 13-year-olds who are likely to be free of the virus.