WEDNESDAY, Feb. 27, 2019 (HealthDay News) — For patients with advanced Merkel cell carcinoma (aMCC), pembrolizumab is associated with durable tumor control and favorable overall survival, according to a study published online Feb. 7 in the Journal of Clinical Oncology.

Paul Nghiem, M.D., Ph.D., from the University of Washington in Seattle, and colleagues treated 50 adults (median age, 70.5 years) naive to systemic therapy for aMCC with pembrolizumab for up to two years.

The researchers found that the objective response rate (ORR) to pembrolizumab was 56 percent (complete response, 24 percent; partial response, 32 percent), with ORRs of 59 and 53 percent in virus-positive and virus-negative tumors, respectively. Patients were followed for a median of 14.9 months. The median response duration was not reached in the 28 responders. The median progression-free survival (PFS) was 16.8 months; the 24-month PFS rate was 48.3 percent. There was a 68.7 percent rate of 24-month overall survival (OS), and median OS time was not reached. There was no correlation for tumor viral status with ORR, PFS, or OS; patients with programmed death ligand-1-positive tumors had a trend toward improved PFS and OS. Overall, 28 percent of the 50 patients had grade 3 or greater treatment-related adverse events, resulting in discontinuation in seven patients and one death related to treatment.

“Immunotherapy has revolutionized the treatment landscape for patients with aMCC, which until recently carried a uniformly poor prognosis,” the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including Merck, which manufactures pembrolizumab and provided funding for the study.

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