CTLA4 and cancer: Immune checkpoint inhibitors (CPI) are transforming the landscape of cancer care and are even approved for tumor-agnostic indications.1-3 These medications block the interaction of immune checkpoint proteins on tumor cells, thus allowing for immune activation4; they include inhibition of programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T lymphocyte-associated 4 (CTLA-4), and most recently, lymphocyte activation gene-3 (LAG3).5