For example, patients with KIT exon 11-mutant GIST have a greater objective response rate (ORR) and longer median progression-free survival (PFS) with front-line imatinib treatment than GIST patients with KIT exon 9-mutant or KIT/PDGFRA “wild-type” (non-mutant) genotypes [8, 9]. Here, PDGFRA is linked to gastrointestinal stromal tumor.