ASCO 2016: Melanoma 3-year survival is robust after pembrolizumab treatment

by Bruce Sylvester: A follow-up evaluation of subjects from the phase 1b trial (KEYNOTE-001) of newly diagnosed and previously treated patients with advanced melanoma revealed a 40% survival rate three years after initiating pembrolizumab therapy.

Notably, the finding did not vary significantly between treatment naive subjects and those who had already received other treatments.

The findings were presented in June, 2016 at the ASCO/American Society of Clinical Oncology annual meeting.

“New therapies that block the PD-1 are extending survival for many patients, and for some may offer the prospect of living longer than ever after a diagnosis with advanced melanoma. In a matter of a few years, these therapies have truly transformed the outlook for patients with melanoma and many other hard-to-treat cancers,” said ASCO spokesperson Don S. Dizon, MD, Associate Professor at Harvard Medical School and Clinical Co-Director of Gynecologic Oncology at the Massachusetts General Hospital (MGH) Cancer Center in Boston.

Investigators enrolled 655 subjects diagnosed with advanced melanoma, and 75% had already received other treatments, including ipilimumab.

Subjects received pembrolizumab at 2 or 10 mg/kg every three weeks, or 10 mg/kg every two weeks. They remained on treatment until showing disease progression, intolerable toxicity or there was an investigator decision to withdraw the subject.

Three-year overall survival rate for patients treated with pembrolizumab was 40%. Median overall survival was 24.4 months.

Survival rates varied slightly according to prior treatment for melanoma.

For treatment naïve subjects, survival was higher, at 45%.

Three-year survival rates were the same, 41%, for those who had received ipilimumab and those who had not.

Average time of pembrolizumab treatment was 11.3 months.

Sixty-one (9%) subjects stopped pembrolizumab after achieving complete response, and 97% remained in remission at time of the new analysis.

Among subjects in remission after stopping pembrolizumab, median time in remission after stopping treatment was 10 months and ongoing.

Pembrolizumab was generally well tolerated.

The researchers noted that even though it is difficult to make any definitive conclusions based on this single-arm, early phase trial, the survival data suggest a benefit from pembrolizumab regardless of prior treatments.

Pembrolizumab was initially approved in the United States in September 2014 for the treatment of advanced melanoma, based on data from KEYNOTE-001.