Women taking GlaxoSmithKline's experimental human papillomavirus vaccine, Cervarix -- which has been shown in studies to be 100% effective in preventing infection with HPV strains 16 and 18 -- have high levels of antibodies against the strains for up to four-and-a-half years after receiving the drug, according to a study published in the April 6 online edition of the journal Lancet, BBC News reports (BBC News, 4/5). The two HPV strains together cause about 70% of cervical cancer cases (Kaiser Daily Women's Health Policy Report, 2/23). Diane Harper, director of the Gynecologic Cancer Prevention Research Group at Dartmouth Medical School, and colleagues also found that Cervarix has been shown to prevent HPV strains 31 and 45, which together with strains 16 and 18 cause more than 80% of cervical cancer cases (Hall, Toronto Star, 4/6). According to a GSK release, the study shows that protection against strains 31 and 45 also lasts up to four-and-a-half years. Harper and colleagues for up to 53 months followed 776 of the girls and women enrolled in an earlier study on the vaccine (GSK release, 4/6). The results of the previous study were published in the Nov. 13, 2004, issue of the Lancet. The earlier study tested the vaccine on 1,113 girls and women ages 15 to 25 in the U.S., Canada and Brazil. The women were given three doses of Cervarix or a placebo and followed for up to 27 months (Kaiser Daily Women's Health Policy Report, 11/15/04).

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"These findings set the stage for widescale adoption of HPV vaccination for prevention of cervical cancer," Harper said (Reuters, 4/5). GSK has submitted Cervarix for European approval and expects to file for FDA approval in the second half of 2006, Dow Jones reports (Berton, Dow Jones, 4/5). Gary Dubin, GSK vice president for HPV vaccine clinical development and co-author of the study, said the study indicates Cervarix could be a "broader" vaccine, protecting against 80% of cervical cancer cases, the Philadelphia Inquirer reports. However, Merck HPV researcher Eliav Barr said Dubin's analysis is "unorthodox," adding that Merck is testing its experimental HPV vaccine, Gardasil, for protection against additional HPV strains (Ginsberg, Philadelphia Inquirer, 4/6). Merck in October 2005 announced that Gardasil in clinical trials was 100% effective in preventing infection with strains 16 and 18. The company in February announced that FDA had granted priority review for Gardasil (Kaiser Daily Women's Health Policy Report, 2/9). Merck said it expects FDA to act on its application by June 8. Although Merck's and GSK's vaccines are "moving closer to the U.S. market," it will be "years" before researchers know if booster shots of the vaccines will be necessary, USA Today reports. "It's not surprising that there's still a strong immune response four years out, Christopher Crum -- director of women's and perinatal pathology at Brigham and Women's Hospital in Boston who was not involved in the trials -- said, adding, "The real question is whether that will be maintained decades later" (Rubin, USA Today, 4/6).