Clayton D. Harro, MD, ScM, research associate at the Johns Hopkins University's Center for Immunization Research, and his research team published a report on safety tests of a cervical cancer vaccine in the Feb. 21 issue of the Journal of the National Cancer Institute (JNCI). The vaccine is meant to fend off the disease by preventing infection with the common human papillomavirus (HPV), which is known to be the cause of 90% of all cervical cancers. Not all strains of HPV cause cervical cancer, but infection with a strain known as HPV-16 is thought to be a cause of about half of all cervical cancer cases.

When researchers gave the vaccine to 58 women and 14 men who volunteered for the study, it produced an immune system response in most of them that was 40 times higher than a typical immune response to a natural HPV infection. In the three-month follow-up period, the most serious side effect was mild irritation at the site where the vaccine was injected.

"This is the first preventive cancer vaccine candidate of this type (HPV-16) that has been developed and tested in humans and found to be both well-tolerated and capable of inducing a strong immune response," Harro says. "We look forward to ultimately developing a preventive vaccine that provides a new tool in our preventive portfolio for HPV disease; the desire is to develop one that both prevents infections as well as limits disease."

The vaccine is made mainly of proteins from HPV-16, in the same way that flu vaccines are made from parts of influenza viruses. It's meant to stimulate the immune system to produce antibodies to HPV, preventing infection by the virus and the cervical cancer that could develop because of it.

A cancer vaccine expert with the American Cancer Society (ACS) says Harro's report is good news. "The immune system responds to and eliminates many HPV infections on its own, so if you increase the immune response 40-fold, that may make a huge difference in how many people exposed to HPV actually become infected, and so become at risk of developing cervical cancer," says T.J. Koerner, PhD, scientific program director in the research department of the ACS.

In the same issue of JNCI, researchers led by Allan Hildesheim, PhD, of the National Cancer Institute's Division of Epidemiology and Genetics, report evidence that some variants (subtypes) of HPV-16 put women at greater risk for cervical cancer than other variants.

In a study involving more than 10,000 women in Costa Rica, Hildesheim's team learned that women infected with a variant of HPV-16 known as NE (non-European) were 11 times more likely to develop cervical cancer than those exposed to other variants of HPV-16.

Koerner says this new information will likely lead scientists to include the NE variant in the design of future cervical cancer vaccines which most likely will include a "cocktail" of HPV proteins for the widest possible protection against the virus.

Much work remains to be done before these vaccines are perfected and become widely available, Koerner says. But he adds that with cervical cancer striking more than 12,000 women in the United States every year and hundreds of thousands worldwide, the vaccines may make "an enormous difference" in the fight against the disease in the future.

"Developing a vaccine has great potential for becoming one of the new prevention strategies for cervical cancer," says Koerner. "This is a heartening development in the fight against a major cancer, and is very encouraging work."