Background: The impact of immune-related adverse events (irAEs) occurring from adjuvant use of immunotherapy and of their management on relapse-free survival (RFS) and overall survival (OS) outcomes is currently not well understood.
Patients and methods: E1609 enrolled 1673 patients with resected high-risk melanoma and evaluated adjuvant ipilimumab 3 mg/kg (ipi3) and 10 mg/kg (ipi10) versus interferon-α. We investigated the association of irAEs and of use of immunosuppressants with RFS and OS for patients treated with ipilimumab (n=1034).
Results: Occurrence of grades 1-2 irAEs was associated with RFS (5 years: 52% (95% CI 47% to 56%) vs 41% (95% CI 31% to 50%) with no AE; p=0.006) and a trend toward improved OS (5 years: 75% (95% CI 71% to 79%) compared with 67% (95% CI 56% to 75%) with no AE; p=0.064). Among specific irAEs, grades 1-2 rash was most significantly associated with RFS (p=0.002) and OS (p=0.003). In multivariate models adjusting for prognostic factors, the most significant associations were seen for grades 1-2 rash with RFS (p<0.001, HR=0.70) and OS (p=0.01, HR=0.71) and for grades 1-2 endocrine+rash with RFS (p<0.001, HR=0.66) and OS (p=0.008, HR=0.7). Overall, grades 1-2 irAEs had the best prognosis in terms of RFS and OS and those with grades 3-4 had less RFS benefits and no OS advantage over no irAE. Patients experiencing grades 3-4 irAE had significantly higher exposure to corticosteroids and immunosuppressants than those with grades 1-2 (92% vs 60%; p<0.001), but no significant associations were found between corticosteroid and immunosuppressant use and RFS or OS. In investigating the impact of non-corticosteroid immunosuppressants, although there were trends toward better RFS and OS favoring cases who were not exposed, no significant associations were found.
Conclusions: Rash and endocrine irAEs were independent prognostic factors of RFS and OS in patients treated with adjuvant ipilimumab. Patients experiencing lower grade irAEs derived the most benefit, but we found no significant evidence supporting a negative impact of high dose corticosteroids and immunosuppressants more commonly used to manage grades 3-4 irAEs.
Keywords: melanoma.
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