Two not-yet-approved vaccines that fight the leading cause of cervical cancer may hold broader promise than researchers had previously noted.
The vaccines are Gardasil, made by Merck, and Cervarix, made by GlaxoSmithKline. The vaccines both target types of human papillomavirus (HPV) that can -- but don’t always -- lead to cervical cancer. Merck and GlaxoSmithKline are WebMD sponsors.
New data on the vaccines include these findings:
--Gardasil may offer some protection against cervical cancer, precancerous lesions, and genital warts in women previously exposed to certain types of HPV.
--Gardasil may protect against cervical cancer, genital warts, and persistent infection with four types of HPV for five years.
· Cervarix may be effective for more than four years and may offer broader protection against HPV infection than previously thought.
About HPV and Cervical Cancer
HPV is transmitted through sexual contact. It’s very common; many people are infected and don’t know it.
HPV is a leading cause of cervical cancer, the No. 2 cause of cancer deaths among women worldwide. But HPV doesn’t always lead to cervical cancer.
The American Cancer Society estimates that 9,710 women in the U.S. will be diagnosed with invasive cervical cancer in 2006. Cervical cancer is a major problem in developing countries that don’t have good access to screening tests, such as the Pap test, which checks for abnormalities of the cervix (the narrow neck of a woman’s uterus) that may be cancerous or precancerous.
About the Vaccines
There are more than 100 types of HPV. Gardasil targets four high-risk types (types 6, 11, 16, and 18). Cervarix targets HPV types 16 and 18, the highest-risk types.
The vaccines would not wipe out cervical cancer, since not all cervical cancers are caused by HPV. Gardasil has gone through phase II and phase III trials, which are required for FDA approval. Phase III trials of Cervarix are under way.
Both vaccines are given in three doses. The second dose is given two months after the first dose. The third dose is given four months after the second dose.
Neither vaccine has been approved in the U.S. yet. Gardasil is currently getting a priority review by the FDA, and Cervarix is expected to be submitted for FDA approval by the end of 2006.
Other HPV vaccines are also in the works.
Gardasil: 5 Years of Protection?
Gardasil may protect against cervical cancer, genital warts, and persistent infection with HPV types 6, 11, 16, and 18 for five years, a new study shows.
The study included 552 women in Brazil and Europe. The women, who were 16-23 years old, either got three doses of a placebo (empty vaccine) or Gardasil.
All of the women were studied for at least three years; 241 were followed for five years. The researchers found “highly effective” protection against persistent infection with HPV types 6, 11, 16, or 18, cervical cancer, and genital warts through five years.
The researchers who worked on the study included L.L. Villa, PhD, of the Ludwig Institute for Cancer Research in Sao Paolo, Brazil. The study was presented in Paris at the European Research Organization on Genital Infection and Neoplasia’s sixth international multidisciplinary congress.
Gardasil & Women With HPV Exposure
Daron Ferrris, MD, of the Medical College of Georgia in Augusta, studied a subset of the nearly 18,000 women who participated in the Gardasil vaccination trials.
Ferris focused on more than 4,700 women who had previous exposure to at least one of the HPV types covered by Gardasil, following them for an average of two years.
During that time, Gardasil was “100% effective” in protecting against cancerous and precancerous lesions and “highly effective” in preventing genital warts and vaginal and vulvar lesions in those women, Ferris writes.
Ferris’ findings were presented in Paris at the European Research Organization on Genital Infection and Neoplasia’s sixth international multidisciplinary congress.
Cervarix: More Than 4 Years of Protection?
Cervarix may be effective for more than four years, states a study in The Lancet.
The researchers included Diane Harper, MD, of New Hampshire’s Dartmouth Medical School. Harper and colleagues followed about 800 women who had participated in a 2003-2004 Cervarix study conducted in the U.S., Canada, and Brazil. Participants either got three doses of Cervarix or a placebo on the same dosing schedule used in the Gardasil trials.
The women who got Cervarix continued to have high levels of antibodies against the HPV types targeted by Cervarix -- HPV types 16 and 18 -- “for up to 4.5 years,” write Harper and colleagues.
The researchers also found some evidence that Cervarix may also protect against infection with HPV types 45 and 31. However, Harper’s team notes that a high frequency of multiple infections complicated those analyses and that the vaccine hasn’t shown protection against HPV types beyond types 16 and 18 in other trials.
Merck funded both Gardasil studies. The Cervarix study was funded by GlaxoSmithKline Biologicals.
By Miranda Hitti, reviewed by Ann Edmundson, MD
SOURCES: European Research Organization on Genital Infection and Neoplasia’s 6th International Multidisciplinary Congress, Paris, April 23-26, 2006. WebMD Medical News: “Cervical Cancer Vaccine Nearing FDA Review.” American Cancer Society: “What are the Key Statistics about Cervical Cancer?” WebMD Medical News: “Cervical Cancer Vaccine Shows Promise.” News release, Merck. Harper, D. The Lancet, April 6, 2006; online edition.