Three clinical trials of the immunotherapy pembrolizumab (Keytruda) have shown that it is active against a rare subtype of skin cancer, mucosal melanoma. The findings were presented by Butler et al at the 2017 European Cancer Congress (ECCO).1 Mucosal melanoma has often been excluded from immunotherapy treatments for the disease. Mucosal melanoma occurs in the moist surfaces that line the body’s cavities, such as the airways, digestive tract, and genitourinary tracts; there is no known cause. It makes up about 1% of all melanomas and has a poor prognosis, usually because of late diagnosis—the majority of patients with metastatic disease survive for less than 1 year on conventional treatments.
Marcus Butler, MD
Reporting the results from three trials of pembrolizumab for patients with advanced melanoma, Marcus Butler, MD, a medical oncologist at the Princess Margaret Cancer Centre, Toronto, told ECCO 2017 that 84 of the 1,567 patients in the KEYNOTE-001, KEYNOTE-002, and KEYNOTE-006 studies had advanced mucosal melanoma.
Patients in the KEYNOTE trials received pembrolizumab intravenously at doses of 2 mg/kg or 10 mg/kg every 3 weeks, or 10 mg/kg every 2 weeks. Ninety percent of the mucosal melanoma patients had already received at least one prior treatment, and 39% of them had received the monoclonal antibody ipilimumab (Yervoy).
“Sixteen of these patients (19%) responded to treatment with pembrolizumab, of whom 12 are still alive without their disease progressing and, so far, the longest time some of these patients have continued to be successfully treated is more than 27 months,” he said.
Dr Butler added, “Our results show that patients benefited from pembrolizumab regardless of whether or not they had been pretreated with ipilimumab.”
Of the 1,483 patients in these KEYNOTE trials who had other forms of advanced melanoma and who received at least one dose of pembrolizumab, 33% responded to the treatment; 72% were still alive without their disease progressing; and the median overall survival time was nearly 2 years. Median overall survival for patients with mucosal melanoma was 11.3 months.
“Immunotherapy for melanoma has revolutionized treatment of the disease. There are some patients with mucosal melanoma who have had complete responses to pembrolizumab and essentially return to a normal life. Some have less spectacular responses, but they still benefit from therapy. In earlier studies, mucosal melanoma was excluded since it is a rare subtype. These findings suggest that mucosal melanoma patients should be offered immunotherapy as standard of care and not excluded.” ■
1. Butler M, Hamid O, Ribas A, et al: Efficacy of pembrolizumab in patients with advanced mucosal melanoma enrolled in the KEYNOTE-001, 002, and 006 studies. 2017 European Cancer Congress. Abstract 1142. Presented January 29, 2017.