Given the preclinical and clinical data of trials of multimodal treatments including IDO1 inhibitors [32, 34–38, 55, 56], our data on GLI/STAT-mediated regulation of IDO1 expression and immunosuppressive activity support the evaluation of novel therapies involving combinations of HH/GLI, JAK/STAT and IDO1 inhibitors for the efficient treatment of malignancies such as advanced or metastatic BCC and melanoma [32]. Here, GLI1 is linked to skin basal cell carcinoma.