Abstract LB-295: Detection of oncogenic kinase mutations in circulating plasma DNA and correlation with clinical benefit in the phase III GRID study of regorafenib vs placebo in TKI-refractory metastatic GIST.

Abstract Background: GRID is a phase III study for patients with advanced gastrointestinal stromal tumors (GIST) following failure of imatinib (I) and sunitinib (S) who were randomized to receive either the multikinase inhibitor regorafenib (R) or placebo (P). R demonstrated a highly significant improvement in progression-free survival compared with P (HR 0.27, p<0.0001). A preplanned retrospective biomarker analysis was conducted to assess GIST genotypes in GRID patients and to explore the possible impact of different driver oncogene mutations on clinical outcomes. Methods: DNA was isolated from archival tumor tissue and analyzed for KIT mutations via Sanger sequencing. The expectat…