Patients with advanced melanoma treated with a Programmed cell death protein-1 (PD-1) immune checkpoint inhibitor have longer survival than historically treated patients, according to results from a phase 1 clinical trial presented at the American Society of Clinical Oncology annual meeting (June 3-7, 2016; Chicago IL).
Investigators led by Caroline Robert, MD, PhD, Institut Gustave Roussy in Villejuif, France, enrolled 655 patients for the trial and divided them into two groups: one where patients received ipilimumab—a monoclonal antibody—in addition to pembrolizumab and one where patients were ipilimumab-naïve. Participants were treated until intolerable toxicity, progression, or investigator decision. Response was assessed every 12 weeks. After treatment discontinuation, patients were contacted to assess survival every 3 months, with overall survival estimated using a statistical model.
As of September 18, 2015, the data cutoff date, median follow-up duration was 32 months and 358 patients (55%) had died. The estimated rate of 3-year overall survival was 40% with a median of 23.8 months. Interestingly, similar results were observed in both the ipilimumab-treated and ipilimumab-naïve groups where the 3-year overall survival rates were 41% and 45%, respectively.
Further, the overall response rate was 33%, with 73% of responding patients experiencing a response duration of 2 years or longer. Complete responses were also observed in 95 patients (15%), 61 of whom ceased treatment after a median of 23 months. Response duration ranged from 17 to 43 months.
Treatment with prembrolizumab was also well tolerated, with only 8% of patients having to discontinue treatment due to adverse events.
Investigators concluded that prembrolizumab provided long-term survival benefit in patients with ipilimumab-treated and ipilimumab-naïve advanced melanoma, supporting use of the drug in patients with melanoma regardless of prior treatment.
In commenting on the results, ASCO’s chief medical officer Richard Schilsky, MD, said the results of the study add to the growing evidence that “PD-1 inhibitors can produce long-duration disease control and long-term survival for a proportion of patients with melanoma, which is a very exciting and promising development.”
