Survivals following discontinuation of PD-1 inhibitor treatment in advanced melanoma patients

The aim of this study was to evaluate overall survival post-treatment discontinuation survival (OS PTD ) in advanced melanoma patients started on immunotherapy. This retrospective study included all unresectable advanced or metastatic melanoma patients who had permanent treatment discontinuation after receiving at least one cycle of palliative-intent programmed death-1 ± cytotoxic T-lymphocyte associated protein-4 inhibitor treatment from 2014 to 2019. Indications of permanent treatment discontinuation included treatment completion, toxicity or progression. OS PTD was defined as a time of permanent treatment discontinuation to the time of death. Our study ( N  = 96) had 27, 12 and 57 patients who discontinued PD-1 inhibitor treatment due to treatment completion, toxicity and progression, respectively. Median treatment durations received for the treatment completion, toxicity and progression groups were 24, 6 and 3 months, respectively. As expected those patients who had disease progression on immunotherapy had very poor survival compared to those that completed treatment or stopped due to toxicity. A multivariable Cox model excluding the patients who progressed indicated no significant OS PTD differences between the toxicity and treatment completion group (HR, 0.894; 95% CI, 0.232-3.449; P  = 0.871) who received single or dual immunotherapy. Our real-world study highlighted similar, durable survival at PD-1 inhibitor discontinuation due to either toxicity or treatment completion, despite longer treatment duration received in the completion group than toxicity group. Patients with progression on PD-1 inhibitor treatment have very poor survival. Our findings must be interpreted with caution due to its retrospective nature and small sample size.