Researchers at Washington University School of Medicine in St. Louis and Harvard Medical School have shown that a combination of two topical drugs triggers a robust immune response against precancerous skin lesions. The therapy, which includes a chemotherapy drug called 5-fluorouracil with a synthetic form of vitamin D called calcipotriol, activates the immune system's T cells, which then attack the abnormal skin cells. The study published in The Journal of Clinical Investigation involved patients with actinic keratosis, a precursor to squamous cell carcinoma. "We looked at precancerous lesions on patients with sun-damaged skin," says Lynn A. Cornelius, M.D., study co-author and director of the division of Dermatology at Washington University. "Most commonly found on the face, scalp, and arms, these lesions appear abnormal by visual examination and under the microscope but are not full-blown skin cancers. But because these lesions have the potential to develop into a true skin cancer, they are commonly treated. Our study shows this combination therapy is more effective and better tolerated than current treatment practices."
On average, the therapy reduced the number of precancerous skin lesions on the face by almost 88 percent compared with a 26 percent reduction using the standard chemotherapy. While some side effects such as skin scaling and itching were similar with both treatments, patients receiving the investigational therapy reported more redness and increased burning sensations, which are consistent with the immune response it triggers. Interestingly, although not specifically measured, patients who had been treated previously with conventional therapies reported decreased pain and discomfort with the combination treatment. "Because calcipotriol has been shown to induce an immune response, we are now interested in seeing if the anti-tumor immunity of the activated T cells can be recalled later to help prevent both precancerous and cancerous skin lesions," says Cornelius. "We are now planning to re-contact our patients to determine whether there are differences in precancerous and skin cancer rates between the two treatment groups."