CTLA4 and liver cancer: For example, CD8+T cells often display a state of dysfunction and turn into depleted T cells, which cannot effectively eliminate the tumor cells and promote the immune escape reaction of the tumor; In addition, depleted T cells also express programmed death protein 1 (PD1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and other inhibitory receptors, driving the progression of liver cancer (37).