Immune Checkpoint Inhibitor Rechallenge Safety and Efficacy in Stage IV Non-Small Cell Lung Cancer Patients After Immune-Related Adverse Events

The decision to resume immune checkpoint inhibitor (ICI) treatment often remains challenging after grade >2 immune-related adverse events (irAEs). We retrospectively studied the outcomes of ICI rechallenge versus permanent discontinuation in 99 stage IV non-small cell lung cancer (NSCLC) patients. Our finding suggests permanent ICI discontinuation is an appropriate strategy after grade >2 irAEs.Background: Despite their anti-tumor efficacy, immune checkpoint inhibitors (ICIs) are associated with a variety of immune-related adverse events (irAEs). Grade > 2 irAEs require ICI discontinuation. The decision to resume ICI treat-ment often remains challenging. Methods: We retrospectively studied 1051 adult patients with stage IV non-small cell lung cancer (NSCLC) treated with ICIs at a single institution between January 2015 and December 2020, and identi-fied 99 (9.4%) patients with grade >2 irAEs necessitating treatment interruption. Forty patients underwent retreatment (rechallenged group), while 59 discontinued the treatment (discontinued group). Results: Baseline characteristics of patients in the 2 groups were similar. Initial irAEs were less severe in the rechallenged group. After rechallenging, 24 of 40 (60%) patients had recurrence of the same or de-novo irAEs. Twenty (50%) developed second grade > 2 irAEs. No grade 4 irAE or irAE-related death occurred after rechallenging. Using multivariate analysis, no statistically significant differences in overall survival (OS) (HR: 1.10, 95% CI: 0.57-2.15, P = .77) or progression-free survival (PFS) (HR: 0.87, 95% CI: 0.45-1.71, P = .69) were noted between the 2 groups, while the best objective response prior to the initial irAEs was the only variable affecting OS and PFS. Conclusions: Rechallenge was associated with a relative high risk of second grade > 2 irAEs. The risk was less if the initial irAEs were resolved. No differences were seen in survival outcomes of patients who had ICI rechallenge and those who did not. Permanent ICI discontinuation is an appropriate strategy after grade > 2 irAEs, especially severe irAEs.