This is because PD-L1 binding to PD-1 requires complex conformational changes in the ligand, whereas PD-L2 directly binds to PD-1 (59, 60), which demonstrates that PD-L2 would outcompete PD-L1 in binding to PD-1 and could be a means by which cancer cells evade the immune system. The gene discussed is PDCD1LG2; the disease is cancer.