It binds to the PD-1 receptor on T cells, blocking the interaction with PD-L1 on tumor cells, thereby disrupting the immune suppression reaction, promoting T lymphocyte activation, increasing CD4+/CD8+ and Th1/Th2, reducing Treg levels, reconstructing the tumor immune surveillance mechanism, preventing tumor cells from evading the immune system, and ultimately exerting anti-tumor effects (47). This evidence concerns the gene CD4 and neoplasm.