In the last years, the idea of the presence of a highly immunosuppressive environment that participates in the malignant transformation of normal cells, and in tumor onset and progression, has led to an increase in the clinical practice of the use of immune checkpoint inhibitors (ICI), such as anti-PD-1, anti-PD-L1, and anti-CTLA4 immunotherapies, which has been particularly consolidated for melanoma and non-small lung carcinoma treatment. This evidence concerns the gene CTLA4 and neoplasm.