Immunotherapy discontinuation and outcome: A multicenter real-life experience.

Abstract

e14075 Background: Unlike chemotherapy, the optimum treatment duration with Immune checkpoint inhibitors (ICIs) is not clearly established. The aim of this study was to assess the outcome of patients (pts) who discontinued immune-based therapies for any reason except progressive disease. Methods: We conducted an observational, retrospective analysis of 46 consecutive pts with advanced cancer who received ICIs as clinically indicated, at eight Italian institutions. Tumor response to treatment was defined according to RECIST. Median overall survival (OS) and the 95% confidence interval (CI) were estimated with the Kaplan -Meier method. Results: 46 pts (median age 68 years [range 41-86]; male: 65.2%) with advanced cancer (n.39 non-small-cell lung cancer, n.15 renal cell carcinoma and n.2 melanoma) were treated with ICIs: 44 pts received programmed death 1 (PD-1) inhibitors (n.31 nivolumab, n.13 pembrolizumab) and 2 pts programmed death ligand 1 (PD-L1) (n.1 durvalumab, n.1 atezolizumab). A median of 8 cycles were administered [range 1 to 52]. 36 pts discontinued ICIs due to toxicities (diarrhoea, pneumonitis, hepatotoxicity) and 10 pts for reasons non immune-related. The median progression free survival (PFS) from the beginning of ICIs was 12.4 months (mo) [95% CI: 8.2-16.6] and the median OS was 20.0 mo (95% CI: 11.8-28.2). Median PFS from discontinuation of therapy was 5.0 mo [95% CI: 2.7-7.3] and median OS was 16.1 mo (95% CI: 5.4-26.8). Best response achieved according RECIST criteria were: 1 complete response (CR), 18 partial response, 21 stable disease (SD), 2 progressive disease (PR) and 3 non evaluable (NE). During interruption of ICIs 1 pts achieved a PR. Conclusions: This study shows the activity of ICIs, in terms of outcome and durable immune-response, in pts with advanced cancer even after treatment discontinuation.