CHICAGO — At 3 years, 40% of patients with advanced melanoma treated with pembrolizumab are alive regardless of whether they had been treated with ipilimumab or not, follow-up results from the KEYNOTE-001 study reported at the American Society of Clinical Oncology (ASCO) 2016 Annual Meeting.1

Among treatment-naïve patients, the survival rate is 45%, said Caroline Robert, MD, PhD, Gustave Roussy and Paris-Sud University, Villejuif-Paris-Sud, France, adding that “pembrolizumab continues to demonstrate safety and tolerability.”

Most importantly, “complete responses are durable after pembrolizumab discontinuation, with 97% ongoing,” she said.

The phase 1 KEYNOTE-001 study enrolled 655 patients. A total of 135 patients were nonrandomized, ipilimumab-naïve and ipilimumab-treated and received pembrolizumab 2 mg/kg every 3 weeks, 10 mg/kg, every 3 weeks, and 10 mg/kg every 2 weeks.

An additional 173 ipilimumab-treated, 103 ipilimumab-naïve, and 244 ipilimumab-naïve and ipilimumab-treated patients were randomly assigned to receive pembrolizumab 2 mg/kg every 3 weeks vs 10 mg/kg every 3 weeks.

Patients with radiographic progression who were clinically stable could remain on pembrolizumab until progression was confirmed.

A total of 24% of patients had BRAFV600 mutation, 78% had stage M1c disease, 38% had elevated LDH, 75% receive 1 or more prior therapies, and 52% had prior ipilimumab.

As of the September 18, 2015, data cutoff date, median follow-up duration was 32 months (range, 24-46 months) and 358 (55%) patients had died.

For all patients, median overall survival was 24.4 months (95% CI, 20.2-29.0), “with similar results for each dose,” Dr. Robert said. For treatment-naïve patients, median overall survival was 32.3 months (95% CI, 27.2-NR). The 36-month overall survival rate was 41% in both ipilimumab-treated and ipilimumab-naive patients.

Progression-free survival at 36 months was 4.9 months (95% CI, 3.1-5.5) and, for the treatment-naïve patients, 5.0 months (95% CI, 3.7-14.0).

“Responses are durable,” Dr. Robert said. The median duration of response was not reached, and response was ongoing in 66% of all and 69% of treatment-naïve responses.

Grade 3/4 treatment-related adverse events were reported in 17% of patients, compared with 14% at the previous 2014 analysis, with 8% (vs 4% in 2014) leading to discontinuation; to date, no deaths have been reported.

Pembrolizumab is approved for treating advanced melanoma at a dose of 2 mg/kg every 3 weeks.

 

Reference

1. Robert C, Ribas A, Hamid O, et al. Three-year overall survival for patients with advanced melanoma treated with pembrolizumab in KEYNOTE-001. Oral presentation at: ASCO 2016 Annual Meeting; June 3-7, 2016; Chicago, IL.