Discontinuation of anti-PD-1 monotherapy in advanced melanoma-Outcomes of daily clinical practice.

There is no consensus on the optimal treatment duration of anti-PD-1 for advanced melanoma. The aim of our study was to gain insight into the outcomes of anti-PD-1 discontinuation, the association of treatment duration with progression and anti-PD-1 re-treatment in relapsing patients. Analyses were performed on advanced melanoma patients in the Netherlands who discontinued first-line anti-PD-1 monotherapy in the absence of progressive disease (n = 324). Survival was estimated after anti-PD-1 discontinuation and with a Cox model the association of treatment duration with progression was assessed. At the time of anti-PD-1 discontinuation, 90 (28%) patients had a complete response (CR), 190 (59%) a partial response (PR) and 44 (14%) stable disease (SD). Median treatment duration for patients with CR, PR and SD was 11.2, 11.5 and 7.2 months, respectively. The 24-month progression-free survival and overall survival probabilities for patients with a CR, PR and SD were, respectively, 64% and 88%, 53% and 82%, 31% and 64%. Survival outcomes of patients with a PR and CR were similar when anti-PD-1 discontinuation was not due to adverse events. Having a PR at anti-PD-1 discontinuation and longer time to first response were associated with progression [hazard ratio (HR) = 1.81 (95% confidence interval, CI = 1.11-2.97) and HR = 1.10 (95% CI = 1.02-1.19; per month increase)]. In 17 of the 27 anti-PD-1 re-treated patients (63%), a response was observed. Advanced melanoma patients can have durable remissions after (elective) anti-PD-1 discontinuation.