Pembrolizumab effective against mucosal melanoma and bladder cancer

Findings of two studies presented recently at the European Cancer Congress 2017 (ECCO 2017) demonstrates the effect of the PD-1 inhibitor, pembrolizumab, against a rare form of melanoma and bladder cancer.

One study was a post hoc analysis of the KEYNOTE-001, KEYNOTE-002 and KEYNOTE-003 trials, in which 84 of 1,567 (5 percent) patients were diagnosed with mucosal melanoma. Overall response rate (ORR) among these patients who received pembrolizumab was 19 percent, disease control rate (DCR) was 31 percent, median progression-free survival (PFS) was 2.8 months and median overall survival (OS) was 11.3 months. [ECCO 2017, abstract 1142]

Among the 19 percent of patients who responded to pembrolizumab, median time to response was 12.4 weeks, median duration of response was 27.6 months, and 75 percent were still alive without disease progression at the time of analysis.  

For the rest of patients with other forms of melanoma who received pembrolizumab, ORR was 33 percent, DCR was 47 percent, median PFS was 4.2 months and median OS was 23.5 months.

“Immunotherapy has revolutionized the treatment of melanoma. Previously, patients with mucosal melanoma were excluded from anti–PD-1 therapy since it is considered a rare subtype. Our findings suggest that these patients should be offered immunotherapy as well. Response rates may not be as good as with other types of melanoma, so further studies to improve benefit will be needed,” said investigator Dr Marcus Butler of Princess Margaret Cancer Centre, Toronto, Ontario, Canada.

Mucosal melanoma is a rare form of melanoma occurring on the mucosal surfaces of the head and neck, anorectum and vulvovaginal regions. Having no known cause and with no associations with UV reported, it presents late and has a poor prognosis. [Cancer Treat Res 2016;167:295-320]

Another study presented was the phase III KEYNOTE-045 trial, which showed that treatment with pembrolizumab resulted in longer OS with minimal side effects for patients with bladder cancer previously treated with chemotherapy.

In this 2-year study where 542 patients were recruited, patients treated with pembrolizumab fared better than those treated with chemotherapy in terms of OS (median, 10.3 vs 7.4 months; p=0.0022) and objective response rate (21 vs 11 percent). [ECCO 2017, abstract 3LBA; N Engl J Med 2017, doi:10.1056/NEJMoa1613683]

Patients treated with pembrolizumab experienced less treatment-related adverse effects of any grade (61 vs 90 percent) or grade 3–5 (15 vs 49 percent) compared with those who received chemotherapy.

“The superior OS combined with lower rates of adverse effects support pembrolizumab as a new standard of care for advanced urothelial cancer that progressed after chemotherapy,” said Dr Andrea Necchi of the Department of Medical Oncology at the Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.

Bladder cancer is the ninth most common cancer in the world, with 430,000 new cases diagnosed in 2012. [Eur Urol 2017;71:96-108]