Late-onset adverse events of anti-PD1 therapy in melanoma patients: An observational study from MELBASE, a nationwide prospective cohort

Background: Late-onset adverse events (AEs) of anti-programmed cell death 1 (anti-PD1) antibodies have not been systematically described. Objectives: The purpose was to evaluate late-onset AEs in melanoma patients treated with anti-PD1 administered for at least 2 years in a real-life setting. Methods: Patients were screened from MelBase, a French multicentric biobank dedicated to the prospective follow up of unresectable stage III or IV melanoma. The study included 119 patients who received anti-PD1 during at least 2 years from January 2013 to November 2019. Median follow up was 41.7 months (range, 25.2-57.5 months). Fifty-three patients received nivolumab and 66 patients received pembrolizumab. Results: AEs occurred in 99 patients (83%) with a median time of 13.3 months (range, 0-53.9 months), including severe AEs (grade 3 or 4) in 30 patients (30%). Late-onset AEs, mostly grades 1 or 2, occurred in 51 (43%) patients and led to 5 (4%) hospitalizations, of which 4 were severe. Factors associated with lateonset AEs in multivariate analysis were early-onset AEs (within the first 2 years of treatment) and treatment duration (P = .02 and P = .03, respectively). Conclusions: Our data demonstrate the possibility of late-onset AEs occurring after 2 years of anti-PD1 therapy. Late-onset AEs appear frequently and were mostly mild or moderate. Early-onset AEs and prolonged anti-PD1 treatment may increase the risk of late-onset AEs.