CHICAGO, Sept. 20 -- Immunization with Gardasil, a vaccine designed to prevent infection with human papilloma virus types 6, 11, 16, and 18 may also offer women significant protection against so-called "cousins" of those viral strains, reported researchers here.
In clinical trials of more than 9,000 women randomized to vaccine or placebo, there were only 26 cases of precancerous lesions caused by HPV types 31, 33, 35, 52, and 58-all cousins of HPV type 16-compared with 48 such cases among women in the placebo group (95% CI 10 to 68, P
There was a similar reduction in pre-cancerous lesions caused by HPV types 39, 45, and 59, which are related to HPV type 18 -- eight cases in the vaccine arm versus 15 cases in the control arm -- but the difference was not statistically significant, he said.
Dr. Brown reported results of the pre-planned, subgroup analysis of the FUTURE I and II trials (Females United To Unilaterally Reduce Endo/ectocervical Disease) at the Interscience Conference on Antimicrobial Agents and Chemotherapy.
"We had hoped that we would see some cross-protection against other strains of human papilloma virus," he said. "This is very good news for women because they are getting extra protection with the vaccine."
"The high degree of cross-protection against additional oncogenic human papilloma virus types may provide an extra measure of protection for young women vaccinated with the quadrivalent human papilloma virus vaccine," said Dr. Brown.
The trials randomized 4,616 women to a three-dose regimen of Gardasil and 4,675 to placebo. The vaccine was virtually 100% successful in preventing infection with human papilloma virus types 6, 11, 16, and 18. Types 6 and 11 are responsible for about 90% of genital warts while types 16 and 18 account for 70% of the cancers and pre-cancerous lesions associated with HPV infection.
Overall, looking at 10 oncologic types of HPV -- 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59 -- the vaccine reduced risk of infection by 38%. Dr. Brown said that these additional oncologic types of HPV account for up to 20% of cervical cancers.
"This really is important information for women," said Scott Hammer, M.D., of Columbia University. "[This] study offers strong support that Gardasil is about 35% to 40% effective in preventing infection with other types of human papilloma virus that cause cancer."
Dr. Brown said that the results of the study should be further encouragement for women and girls to become vaccinated with Gardasil. "My daughter who is 26 has been vaccinated and if the vaccine becomes available for men and boys, I will encourage my sons to be vaccinated as well," he said.
Dr. Hammer noted that human papilloma virus is responsible for several diseases specific to men, including penile cancer, and by vaccinating men it would also help to prevent transmission to women.
Dr. Brown said work is under way on potentially breakthrough technology that may allow for a vaccine that would cover all oncological types of human papilloma virus.
The study was funded by Merck, which developed and markets the Gardasil vaccine. Dr. Brown said he consults for Merck. Dr. Hammer has disclosed possible financial conflicts of interest with Boehringer Ingelheim, Bristol-Myers Squibb, Gilead, GlaxoSmithKline, Roche-Trimeris, Shionogi, Shire BioChem, Tibotec-Virco, Triangle.
Complete ICAAC CoveragePrimary source: Online Abstracts: 47th Interscience Conference on Animicrobial Agents and Chemotherapy, Sept.17-20, 2007Source reference: Brown D, et al "HPV Type 6/11/16/18 Vaccine: First Analysis of Cross-Protection against Persistent Infection, Cervical Intraepithelial Neoplasia (CIN), and Adenocarcinoma In Situ (AIS) Caused by Oncogenic HPV Types in Addition to 16/18." Abstract G-1720b: 47th Interscience Conference on Animicrobial Agents and Chemotherapy, Sept.17-20, 2007.
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