CTLA4 and cancer: Monoclonal antibodies targeting programmed cell death protein-1 (PD-1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) revolutionized the field by demonstrating that reinvigorating exhausted T cells in cancer patients was not only a viable strategy, but also was capable of inducing durable remissions in a subset of patients with diverse malignancies [22].