CTLA4 and type 1 diabetes mellitus: Finally, prior studies have shown PD-1 blockade to be the primary driver of accelerated autoimmunity in adult mice (51–53), but ICI-T1DM can also develop in patients with cancer who are treated with combination ICI regimens (e.g., anti–PD-1 + anti-cytotoxic T lymphocyte antigen [CTLA-4]) (Supplemental Figure 4A) (4–6).