Since the clinical relevance of circulating immune checkpoints as predictors of clinical outcome has yet to be defined in GIST patients, we carried out a Kaplan–Meier survival analysis in order to understand the potential prognostic value of plasma PD-1, PD-L1, BTN3A1, and pan-BTN3As in advanced GIST patients, suggesting that their plasma concentrations could be helpful, in the future, for predicting patient survival (Figure 4). This evidence concerns the gene BTN3A1 and gastrointestinal stromal tumor.