© 2005 Oxford University Press
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Two HPV Vaccines Yielding Similar Success
New Jersey-based Merck & Co., and GlaxoSmithKline (GSK), based in England, are in the final phase of clinical trials of their vaccines against human papillomavirus (HPV) types 16 and 18, which are associated with 70% of all cases of cervical cancer.
Merck's Gardasil vaccine also provides immunity against HPV 6 and 11, which cause 90% of all cases of genital warts, whereas GSK's Cervarix vaccine provides immunity against only HPV 16 and 18.
Earlier trials of both vaccines have been promising. Randomized, double-blind, placebo-controlled studies involving more than 2,200 young women at several sites have shown both vaccines to be at least 90% effective in protecting against infection with the targeted viruses. Preliminary data suggest that immunized young women followed for more than 2 years showed no evidence of precancerous lesions caused by these HPV types, whereas women in the placebo groups did develop lesions. Merck published the results of its phase II clinical trials in 2002 and 2005, and GSK's results were published in 2004.
Merck's phase III trial involves more than 20,000 women at more than 100 sites worldwide and is expected to provide results later this year. GSK enrolled about 30,000 women in its phase III trial. Both companies are also testing the vaccines on men and adolescent boys and girls. In tests in adolescents, researchers are analyzing only the vaccine's safety and the subjects' immune response, not cervical changes associated with HPV infection.
The National Cancer Institute is conducting a long-term, independent trial in 9,000 women in Costa Rica using GSK's vaccine. NCI researchers are using the trial to help develop second-generation HPV vaccines. Future vaccines are expected to target additional carcinogenic HPV types.
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  I. de Melo-Martin The promise of the human papillomavirus vaccine does not confer immunity against ethical reflection. Oncologist, April 1, 2006; 11(4): 393 - 396. [Abstract] [Full Text] [PDF]
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