Updates from clinical trials of Keytruda (pembrolizumab) for melanoma show that besides its known benefits for people with typical melanoma, the treatment is also effective against mucosal melanoma — a rare version of the cancer, growing in mucosal surfaces of the body.
Researchers shared their updates at the European Cancer Congress 2017 (ECCO), held recently in Amsterdam.
Keytruda is an immunotherapy targeting the PD-1 checkpoint molecule. In this way, it activates immune responses toward the cancer. Both European and U.S. agencies have approved its use for advanced melanoma.
Of the 1,567 patients in three clinical trials including melanoma patients (NCT01295827, NCT01704287, and NCT01866319), 84 had mucosal melanoma, a type of melanoma not caused by UV irradiation. Sixteen of them (19 percent) responded to treatment with pembrolizumab, and 12 showed evidence of no disease progression. Some of these patients are still being successfully treated more than 27 months later, said Dr. Marcus Butler, a medical oncologist at Canada’s Princess Margaret Cancer Centre.
Of the remaining patients with other melanoma types, one-third responded to the treatment and 72 percent did not see their disease progress. The median overall survival was almost two years. Those with mucosal melanoma survived for a median of 11.3 months.
“Immunotherapy for melanoma has revolutionized treatment of the disease,” Butler said in a press release. “Some patients with mucosal melanoma have had complete responses to pembrolizumab and essentially return to a normal life. Some, of course, have less spectacular responses, but they still benefit from therapy.”
Because mucosal melanoma is such a rare condition, making up only 1 percent of all melanomas, such patients have traditionally been excluded from melanoma clinical trials. Since a diagnosis is often set in late stages of the disease, the prognosis is often poor, with patients surviving for less than a year once the cancer starts spreading.
“The data presented here are important because they prove that patients with mucosal melanoma can benefit from anti-PD-1 therapy and should not be excluded from this treatment,” said Butler. “At this stage, we don’t know why some mucosal melanoma patients responded to pembrolizumab while others did not. This is an important question and research is ongoing.”
While 90 percent of patients had received earlier treatment, and 39 percent had been treated with the antibody drug Yervoy (ipilimumab), analyses showed that earlier treatment did not affect their response to Keytruda.
“For rare cancer types, it is difficult to evaluate new treatments in normal-sized trials. But here Butler and colleagues pull three trials together and show that long-lasting responses also occur with pembrolizumab in patients with mucosal melanoma,” said Peter Naredi, ECCO’s president and chair. Naredi, a professor at Sahlgrenska Academy — part of Sweden’s University of Gothenburg — was not involved in the research.
