PDCD1 and cancer: In cancer immunotherapy, glycolysis inhibitors (e.g., 2-DG) or monocarboxylate transporter 1 (MCT1) inhibitors (AR-C155858, MCT1i) synergize with anti-PD-1 antibodies to alleviate lactate-driven immunosuppression and reverse T cell exhaustion, enhancing antitumor responses 144, 145.