Background: Management of checkpoint-inhibitor-induced immune-related adverse events (irAEs) is primarily based on expert opinion. Recent studies have suggested detrimental effects of immunosuppressive treatment with anti-TNF on checkpoint-inhibitor efficacy. Methods: Advanced melanoma patients experiencing grade ≥3 irAEs after treatment with first-line ipilimumab-nivolumab between 2015 and 2021 were included from the Dutch Melanoma Treatment Registry. Progression-free survival (PFS), overall survival (OS) and melanoma-specific survival (MSS) were analyzed according to toxicity management regimen. A cox proportional hazards model was used to account for the confounders age, sex, performance status, lactate dehydrogenase, site of metastases and type of irAE. Results: Out of 771 ipilimumab-nivolumab treated patients, 350 were treated with immunosuppression for severe irAEs. Of these patients, 235 received steroids only and 115 received steroids with second-line immunosuppressants consisting of anti-TNF, mycophenolic acid, tacrolimus and other immunosuppressants. Median PFS was significantly longer for patients treated with steroids (11.3 months) than for patients treated with steroids and second-line immunosuppressants (5.4 months; HR 1.43; 95%CI 1.07-1.90; p = 0.01). Median OS was also significantly longer for the steroids group (46.1 months) than for the steroids and second-line immunosuppressants group (22.5 months; HR 1.64; 95%CI 1.16-2.32; p = 0.005). Results for MSS were similar (not reached versus 28.8 months; HR 1.70; 95%CI 1.16-2.49; p = 0.006). Median PFS, OS and MSS are shown in Table 1. After adjustment for potential confounders, patients treated with steroids + second-line immunosuppressants showed a non-significant trend towards a higher risk of progression (HR_adj 1.40; 95%CI 1.00-1.97; p = 0.05), a higher risk of death (HR_adj 1.54; 95%CI 1.03-2.30; p = 0.04) and of melanoma-specific death (HR_adj 1.62; 95%CI 1.04-2.51; p = 0.032) compared to the steroids group. Conclusions: Second-line immunosuppression for irAEs is associated with impaired PFS, OS, and MSS in advanced melanoma patients treated with first-line ipilimumab-nivolumab, irrespective of being anti-TNF or other second-line immunosuppressants. These findings stress the importance of assessing the effects of differential irAE management strategies, not only in melanoma but also in other tumor types.

*Compared to steroids group.