Five-year survival rates for patients with advanced melanoma treated with pembrolizumab (Keytruda) are 34%, according to the longest follow-up study to date.
Results from the international KEYNOTE-001 study involving 655 patients also show an estimated five-year overall survival rate of 41% for treatment-naïve patients with the PD-1 inhibitor.
Published in the Annals of Oncology, the results represent the longest follow-up data for the immunotherapy, according to a team of study investigators that included Australian oncologists.
The study also showed positive responses in two of four patients receiving second course pembrolizumab.
In the study, adult patients with advanced/metastatic melanoma received pembrolizumab at doses of 2mg or 10mg/kg every two to three weeks.
After a median follow up of 55 months the estimated five-year progression free survival (PFS) was 21% in all patients and 29% in treatment naïve patients.
Among all 655 treated patients, 104 (16%) achieved complete response (CR), 163 (25%) achieved partial response (PR) and 156 (24%) achieved stable disease, for a disease control rate of 65%.
Response was ongoing in 89% (n = 93) of patients overall who achieved CR, and in 63% (n = 102) of patients who achieved PR. The percentage of patients with an ongoing response (92%) was higher in those who were treatment-naïve.
The study investigators said the estimated five year overall survival rates seen with pembrolizumab compared favourably with those seen in trials of ipilimumab (12.3%-28.4%) and nivolumab (34% after 45 months). The study also confirmed the tolerability of pembrolizumab, with no new safety signals compared to previous shorter term follow-up studies.
And although patient numbers were low, the KEYNOTE-001 findings for second-course pembrolizumab compared favourably with other immunotherapies, said the study investigators, including Professor Richard Kefford, Professor of Cancer Medicine at Macquarie University and a Consultant Medical Oncologist at Westmead Hospital, Sydney.
The results “confirm the durable anti-tumour activity of pembrolizumab in advanced and metastatic melanoma”, they concluded.