PDGFRA and gastrointestinal stromal tumor: The patient was treated with imatinib for 3 years and the survival from the time of metastatic relapse lasted for 40.5 months, an interval that is comparable to the median survival time of KIT/PDGFRA-mutant metastatic patients (56.6 months) and definitely higher than that of quadruple-WT GIST (25.2 months) (Supplementary Figure 3), thus reinforcing the relevance of low-allele-fraction KIT mutations in driving TKI-response in GIST.