Merck's HPV Vaccine in Phase III Trial 100% Effective for Two Strains Causing 70% of Cervical Cancer Cases

Main Category: Women's Health / Gynecology
Article Date: 09 Oct 2005 - 19:00 PST

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Pharmaceutical company Merck on Thursday announced that a Phase III, multinational study of its experimental vaccine Gardasil was 100% effective in preventing transmission of two strains of the sexually transmitted disease human papillomavirus, which together cause about 70% of cervical cancer cases, the Los Angeles Times reports. Merck said it will seek FDA approval of Gardasil this year and could begin marketing the drug late next year. The study, which is scheduled to be presented on Friday at a meeting of the Infectious Diseases Society of America in San Francisco, was led by Laura Koutsky of University of Washington and enrolled 12,167 women ages 16 to 26 in 13 countries -- none of whom tested positive for HPV strains 16 or 18 at the time of enrollment (Maugh, Los Angeles Times, 10/7). To be most effective, the vaccine would have to be administered to males and females before they become sexually active (Vrazo, Knight Ridder/Wichita Eagle, 10/7). About 20 million people in the U.S. have a form of HPV; cervical cancer, often caused by HPV, causes the death of about 300,000 people annually worldwide, including roughly 3,700 in the U.S. (Johnson, AP/Long Island Newsday, 10/6).

Study Details, Previous Study
In the study, Gardasil was given to 6,082 women and a placebo was given to 6,075, both in a three dose regimen over six months. Women were followed for an average of two years after enrollment, and none in Gardasil group contracted HPV strains 16 or 18 (Merck release, 10/6). Efficacy fell to 97% in the women who did not receive all of the Gardasil doses or did not follow the study protocol (Los Angeles Times, 10/7). None of the women stopped participating in the study "due to serious vaccine-related adverse events," Merck said (Howard Price, Washington Times, 10/7). A Phase III trial of the vaccine presented in May found that all participants experienced 100% antibody responses to the HPV strains 6, 11 and 16, 99.9% of boys and girls ages 10 to 15 developed antibody responses to HPV strain 18, and 99.1% of 16- to 23-year-old women developed strain 18 antibodies. Strains 6, 11, 16 and 18 of HPV are the most likely to cause cervical cancer or genital warts (Kaiser Daily Women's Health Policy Report, 5/20).

Reaction
"These are stunning results," Margaret Stanley -- an HPV and cervical cancer specialist at the University of Cambridge, who was not involved with the trial -- said, adding, "For a vaccine to show 100% efficacy, even over a short time like two years, is a really good result" (Hawkes, London's Times, 10/7). Deborah Saslow, director of breast and gynecological cancer at the American Cancer Society, said, "The potential, particularly in the undeveloped world, particularly if they can overcome logistics and get the vaccine to those women, could be enormous" (Grady, New York Times, 10/7). Eliav Barr, Merck head of clinical development for the vaccine, said, "To have 100% efficacy is something that you have vary rarely," adding, "We're breaking out the champagne" (AP/Long Island Newsday, 10/6). However, groups including the Family Research Council said giving a vaccine for an STD to young people might encourage them to have sex (Knight Ridder/Wichita Eagle, 10/7).

GSK Competing Vaccine
Pharmaceutical company GlaxoSmithKline is "[h]ot on Merck's heels" with its own HPV vaccine, which it plans to submit for approval in Europe and elsewhere in 2006, GSK CEO Jean-Pierre Garnier told CNBC, the Wall Street Journal reports (Chase, Wall Street Journal, 10/7). GSK's experimental HPV vaccine Cervarix has shown to be 100% effective in preventing transmission of strains 16 and 18 in earlier stage clinical trials (Pierson, Reuters, 10/7). GSK said it plans to recommend Cervarix for girls as young as age 10, while Merck has said it plans to lobby states to require the vaccine for all 12-year-old children before they can enter school. Some parents and health officials object to standardized vaccinations for teenagers and are concerned that children would interpret them as permission to have sex (Kaiser Daily Women's Health Policy Report, 7/6).

Several broadcast programs reported on the cervical cancer vaccine:

• ABCNews' "World News Tonight": The segment includes comments from Carol Brown of Memorial Sloan-Kettering Cancer Center; Christopher Crum of Brigham and Women's Hospital; and Diane Harper of Dartmouth Medical School (McKenzie, "World News Tonight," ABCNews, 10/6).
  


• CBS' "Evening News": The segment includes comments from Barr, Jacob Lalezari, assistant clinical professor of medicine at University of California-San Francisco Mount Zion Hospital, and a woman who participated in the study (Kaledin, "Evening News," CBS, 10/6). The complete segment is available online in RealPlayer.
  


• NBC's "Nightly News": NBC's Robert Bazell discusses the study (Bazell, "Nightly News," NBC, 10/6). The complete segment is available online in Windows Media.
  

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