Vaccines could be used alongside conventional treatments to combat certain forms of cancer, scientists suggest1.
Results from a new Manchester-based clinical trial have added to the growing evidence on vaccines. A leading Cancer Research UK scientist and his team found that a vaccine targeted against certain forms of the human papillomavirus (HPV) was able to shrink lesions in almost half of women with a precancerous disease of the vulva.
Researchers believe the results will help in the search for vaccines for vulval and cervical cancer – both strongly associated with HPV infection – although they caution that it is too early to know how effective this particular vaccine will be.
Scientists at Cancer Research UK’s Paterson Institute, in collaboration with doctors at St Mary’s Hospital, tested out a vaccine called TA-HPV, which was developed by Xenova Research Ltd and is a modified version of the smallpox vaccine. They gave the vaccine to 18 women with vulval intraepithelial neoplasia (VIN) – a condition in which precancerous lesions appear on the lining of the vulva and are very difficult to treat.
Researchers not only monitored the effect of the vaccine on the size of women’s lesions, but also conducted a series of tests to assess whether the vaccine was stimulating an immune response.
They found that 13 of the 18 women developed a specific immune reaction to HPV following vaccination. In 8 of the patients, the diameter of the lesions shrunk by at least 50 per cent, and another four patients experienced significant symptom relief. This is the first time scientists have used vaccines to produce clinical and immunological responses in women with VIN.
Cancer Research UK’s Professor Peter Stern, lead researcher on the study, says: “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 started generating some kind of immune response against their disease. In the new 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.
Professor Stern adds: “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.
“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.”
Professor Stern and his colleagues are currently testing the effect of repeat vaccination in ongoing clinical trials.
Dr John Toy, Medical Director of Cancer Research UK, says: “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.
“The new trial produced some promising early clinical results and has also provided us with some important information about how vaccines could direct the immune system against cancer.”
- Cancer Research63 (Sept 15)
Local charity Wigan Research Fund provided some of the funding for the study, via a Joseph Starkey Fellowship for researcher Emma Davidson.
Cervical and vulval cancer are both associated with two particular types of human papillomavirus – HPV 16 and HPV 18 – and it was these that the vaccine was targeted against.