CTLA4 and cancer: Cancer immunotherapy, particularly immune checkpoint blockade (e.g., anti-PD-1/PD-L1, anti-CTLA-4 antibodies), aims to reinvigorate these exhausted or suppressed CD8+ T cells by blocking inhibitory signals, thereby restoring their anti-tumor activity and leading to durable responses in various cancers, though efficacy varies and resistance can occur (95, 96).