CTLA4 and neoplasm: It has been shown that the combination of CTLA-4 and PD-1 inhibitors is more effective than single therapy, probably because the synergistic effect leads to an increase in the number of tumour-infiltrating lymphocytes, a decrease in regulatory T cells, and an overall improvement in the inhibition of tumour growth, with an overall efficiency of 10.8% (7/65, all in partial remission), a disease control rate of 32.2%, and an overall survival time for cholangiocarcinoma was 10.1 months [8].