Lower frequencies of circulating suppressive regulatory T cells and higher frequencies of CD4 + naïve T cells at baseline are associated with severe immune-related adverse events in immune checkpoint inhibitor-treated melanoma.

This study demonstrates that high-dimensional immune profiling can reveal novel blood-based immune signatures associated with risk and mechanism of severe irAEs. Development of severe irAEs in melanoma could be the result of reduced immune inhibitory capacity pre-ICI treatment, resulting in more activated TCM cells after treatment.