Combination 5-FU and synthetic vitamin D found to be effective AK treatment

Washington University dermatologist Dr. Lynn Cornelius, MD, (left) conducts a skin exam with a patient. Photo by Robert J. Boston, Washington University School of Medicine

A combination of two topical drugs—chemotherapeutic agent 5-flourouracil (5-FU) and the psoriasis treatment calcipotriol (synthetic vitamin D)—triggered a robust immune response against actinic keratosis (AK) in a study published online in The Journal of Clinical Investigation (Nov. 21, 2016).

The researchers, from Washington University School of Medicine in St. Louis and Harvard Medical School in Boston, found that the investigational treatment activates the immune system’s T cells, which then attack the abnormal skin cells.

“We looked at precancerous lesions on patients with sun-damaged skin,” said Washington University dermatologist and study co-author Dr. Lynn A. Cornelius, director of the Division of Dermatology, in a press release. “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.”

“The idea behind this study was to induce a heightened immune response in the skin using calcipotriol combined with the 5-fluorouracil that works to destroy the precancerous cells,” Dr. Cornelius said. “In so doing, the destroyed precancerous cells release cell proteins, or antigens, and facilitate the heightened immune system to respond. We compared the two-drug formulation to 5-fluorouracil alone over a shorter application period—four days as opposed to two to four weeks that is typical for the standard treatment of 5-fluorouracil alone.”

The randomized, double-blind clinical trial involved 132 patients with AKs treated at Washington University School of Medicine in St. Louis. Sixty-five of these patients were randomly assigned to receive 5-FU plus 0.005% calcipotriol. The remaining 67 patients served as a control group and received the standard 5-fluorouracil plus Vaseline petroleum jelly. Patients applied the assigned cream twice daily for four days.

Patients in the investigational and control groups began the trial with similar numbers of AKs on each part of the body examined. At each body site evaluated, there were on average about 15 lesions on the face, 22 lesions on the scalp, 14 lesions on the right arm, and 12 on the left arm. Following treatment, facial lesions were reduced by 87.8% in the investigational group versus 26.3% in the control group. On the scalp, lesions were reduced by 76.4% compared with 5.7%. On the right arm, the reduction was 68.8% for the investigational treatment versus 9.6% for the control. On the left arm, the precancerous lesions were reduced by 79% for the investigational treatment compared with 16.3% for the control.

“Because calcipotriol has been shown to induce an immune response, we are now interested in seeing if the anti-tumour immunity of the activated T cells can be recalled later to help prevent both precancerous and cancerous skin lesions,” Dr. Cornelius said.

“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.”