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 (OSPTD) 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. OSPTD 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 OSPTD 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.