Human Papillomavirus: Scientists Announce Vaccine Hope

Scientists at Cancer Research UK's Paterson Institute, in collaboration with doctors at St. Mary's Hospital, tested a vaccine, TA-HPV, and found that it shrank lesions in almost half of women with a precancerous disease of the vulva. The scientists believe the results of their study will help in the search for vaccines against vulval and cervical cancer, both strongly associated with HPV infection, although they caution that it is too early to know how effective TA-HPV will be.

Eighteen women with vulval intraepithelial neoplasia (VIN), a condition in which precancerous lesions appear on the lining of the vulva and are difficult to treat, took TA-HPV, a modified version of the smallpox vaccine. The researchers monitored the vaccine's effect on the size of the women's lesions and conducted tests to assess whether the vaccine was stimulating an immune response.

Thirteen of the 18 women developed a specific immune reaction to HPV following vaccination. In eight of the patients, the diameter of the lesions shrank by at least 50 percent. Another four patients experienced significant symptom relief. The study marks the first time scientists have used vaccines to produce clinical and immunological responses in women with VIN.

Professor Peter Stern, lead researcher, said, "Our results were encouraging, with more than half the women in the trial gaining some clinical benefit, although I think vaccines will prove most useful as part of a combination of treatments. The big advantage vaccines have is that they are relatively free of side effects and have far less impact on a woman's quality of life than surgery, which is currently one of the mainstays of treatment for this condition."

Scientists believe vaccines may be particularly useful in women whose bodies have already begun to generate an immune response against HPV. In this study, women with high levels of immune cells within their lesions before vaccination were significantly more likely to respond to treatment than women with low levels.

"The suggestion is that vaccines work better in some patients than others because there is a need for active immune cells or their products in the vicinity of a lesion. It could be that we'll need to test women beforehand, to identify a group who are most likely to benefit from vaccination," said Stern.

"It's also possible that repeated vaccination may build up the immune response against cancer, in which case it might be necessary to give women a number of shots of vaccine during a course of treatment," Stern explained.

Stern and colleagues are currently testing the effect of repeat vaccination in ongoing clinical trials.

Dr. John Toy, medical director of Cancer Research UK, said, "There are two kinds of cancer vaccines being investigated at the moment: prevention vaccines, to try to stop the disease from developing in the first place, and treatment vaccines, like this one. In the future it's likely that vaccines will play an important role in helping us control certain cancers, particularly those like vulval and cervical cancer which are associated with persistent HPV infection," Toy said.

The study, "Immunological and Clinical Responses in Women with Vulval Intraepithelial Neoplasia Vaccinated with a Vaccinia Virus Encoding Human Papillomavirus 16/18 Oncoproteins," appeared in Cancer Research (2003;63:6032-6041).

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