Late immune-related adverse events in long-term responders to PD-1/PD-L1 checkpoint inhibitors: a multicentre study

Abstract

AbstractData on spectrum and grade of immune-related adverse events (irAEs) in long-term responders to immune checkpoint inhibitors (ICI) are lacking.We performed a retrospective multicenter study to characterized irAEs occurring after a 12-months minimum treatment period with PD-(L)1 ICIs in advanced cancer patients. IrAEs were categorized into “early” (≤12 months) and “late” (>12 months).From September 2013 to October 2019, 436 consecutive patients were evaluated. 223 experienced any grade early-irAEs (51.1%), while 132 experienced any grade late-irAEs (30.3%) (p < 0.0001). Among the latter, 29 (22%) experienced a recurrence of an early-irAEs, while 103 (78%) experienced de novo late-irAEs involving different system/organ. Among patients with late-irAEs, 21 experienced G3/G4 irAEs (4.8%). Median time to onset of early-irAEs was 3.4 months (95%CI: 2.8-4.2), while the median time to onset of late-irAEs was 16.6 months (95%CI: 15.8-17.6). Cumulative time-adjusted risk of disease progression according to both the early-irAEs (HR = 0.63 [95%CI: 0.30-1.29], p = 0.204) and late-irAEs occurrence revealed no statistically significant differences (HR = 0.75 [95%CI: 0.37-1.56], p = 0.452). Also the time-adjusted cumulative risk of death according to both early-irAEs (HR = 0.79 [95%CI: 0.34-1.86], p = 0.598) and late-irAEs (HR = 0.92 [95%CI: 0.49-1.74], p = 0.811) did not show statistically significant differences.Although less frequent than early-irAEs, late-irAEs are quite common in long responders to PD-(L)1 ICIs, and are different in terms of spectrum and grade. Time-adjusted analysis revealed that the cumulative risk of disease progression and death were not significantly reduced in patients who experienced late-irAEs.