PDGFRA and gastrointestinal stromal tumor: In vitro models of KIT/PDGFRA WT GISTs are still lacking, but Flavahan et al. developed an SDH-deficient GIST PDX model carrying epigenetic alterations and consequent overexpression of FGF4 and demonstrated that it was responsive to BGJ-398, a selective inhibitor of FGFR1–4.