Moreover, the expression of immune checkpoints, such as PD-L1, PD-1, and CTLA-4, and their relationship to the clinical phenotype in GIST are emerging as potential prognostic biomarkers and could lead to improved prognostication in GIST, traditionally based on mitotic indices, tumor location, and tumor size [5,11,12,13]. This evidence concerns the gene CTLA4 and gastrointestinal stromal tumor.