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Analysis: More Uses for Gardasil Vaccine?

Posted on: Wednesday, 7 June 2006, 00:00 CDT

By ED SUSMAN

An anti-cancer vaccine that may someday relegate cervical cancer to the history books also silences two other disfiguring and dangerous malignancies of the woman's genital tract.

In reviewing results in which more than 17,000 women participated, researchers at the American Society of Clinical Oncology said that vulvar cancer and vaginal cancer -- diseases that strike about 6,000 American women each year -- are prevented by the vaccine against infection with human papillomavirus.

The vaccine, Merck's Gardasil, could be approved before the end of this month, doctors said at the cancer meeting in Atlanta that attracted more than 25,000 oncologists, scientists and allied health care workers.

Hopefully, Gardasil will be given as a childhood vaccine to everyone, said Robert Ozols, senior vice president of the medical science division at Fox Chase Cancer Center, Philadelphia.

It is particularly exciting to see that the human papillomavirus vaccine may also be effective in preventing vaginal cancers, he told United Press International. I don't think you can overestimate the benefit that this vaccine is going to have.

Already shown to prevent cervical cancer, doctors said new figures indicate that vulvar cancer and vaginal cancer have roots in human papillomavirus and preventing infection with the vaccine stops those cancers, too.

Jorma Paavonen, professor of obstetrics and gynecology at the University of Helsinki, Helsinki, Finland, reported that in the trial of women 15 to 26 years of age who had not been exposed to the sexually transmitted virus, no cases of dangerous pre-cancerous changes occurred among 8,641 women who completed the three-injection vaccine course. The results were analyzed 18 months after the women were inoculated.

However, among the 8,667 women who were given sham vaccine injections, there were 24 cases of the pre-cancerous lesions, said Paavonen at a press briefing during the ASCO meeting that ended Tuesday.

These findings support the prophylactic efficacy of Gardasil in preventing virus- related vulvar and vaginal cancer, he told UPI. The vaccine targets four of the major types of human papillomavirus. Types 16 and 18 are responsible for 70 percent of cervical cancer in the United States, while type 6 and 11 cause most of the cases of genital warts, another disfiguring, uncomfortable and psychologically upsetting skin condition.

Paavonen said the results represented outcomes that pooled data from three clinical trials that were testing Gardasil. Human papillomavirus is detected in 75 percent to 100 percent of vulvar cancers in younger women, he said. He said the virus is closely associated with about two-thirds of vaginal cancers.

In the study group, five women who were vaccinated with Gardasil developed precancerous vulvar and vaginal lesions, but Paavonen said they were caused by human papillomavirus of types other than the ones that the women were vaccinated against. There are 100 different types of human papillomavirus. The vaccine is initially administered, given again two months later, with a final inoculation administered at six months.

Ozols said he was told that approval of the vaccine by the Food and Drug Administration was imminent. He said the decision as to who should get the vaccine would be up to discussions between the FDA and the Centers for Disease Control and Prevention.

Ozols suggested that boys as well as girls should be vaccinated. The ongoing studies suggest that the vaccine is effective in preventing cancer if it is administered before infection with human papillomavirus occurs, and research suggests that infection which is ubiquitous in the world occurs within 18 months of the beginning of sexual activity.

Of course we tested all the participants in the trials to determine if they were na&175;ve -- or uninfected with the virus -- before including them in the study, Paavonen told UPI. We found that about 73 percent of the young women aged 15 to 26 were not infected with the virus and were eligible to participate.

Source: United Press International

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