In a study appearing in the April 19 issue of JAMA, Antoni Ribas, M.D., Ph.D., of the University of California – Los Angeles, and colleagues examined tumor response and overall survival following administration of the antibody pembrolizumab among patients with advanced melanoma.
Pembrolizumab, an antibody against programmed cell death protein 1 (PD-1), is an approved treatment for unresectable or metastatic melanoma. The PD-1 pathway limits immune responses to melanoma and can be blocked with pembrolizumab. In this phase 1 clinical trial, 655 patients with advanced or metastatic melanoma received pembrolizumab intravenously of varying doses and duration. Median duration of follow-up was 21 months. The study was performed in medical centers in Australia, Canada, France, and the United States.
The researchers found that pembrolizumab treatment was associated with an objective response rate (best overall response of complete response or partial response) of 33 percent, 12-month progression-free survival rate of 35 percent, a 23-month median overall survival, and a grade 3 or 4 adverse event rate of 14 percent, regardless of previous treatment with the antibody ipilimumab or pembrolizumab dose or schedule. In treatment-naive patients, the overall response rate was 45 percent, the 12-month progression free survival rate was 52 percent, and the median overall survival was 31 months with a 12-month survival rate of 73 percent and a 24-month survival rate of 60 percent.
Four percent of patients discontinued treatment because of a treatment-related adverse event. Treatment-related serious adverse events were reported in 9 percent of patients. There were no drug-related deaths.