PDGFRA and melanoma: By comparing the TIS score in our GIST series with the TIS score distribution in several tumor types (collected in TCGA database), we can see that the SDH-deficient TIS score is closer to that of glioblastoma multiforme and kidney renal papillary cell carcinoma, emerging as the lowest with respect to other GIST molecular subgroups (both KIT-mutant and PDGFRA-mutant) that showed a TIS score more similar to hot tumors (such as melanoma and lung cancer).