199P Suppression of mutant Kirsten-RAS (KRAS G12C) non-small cell lung cancer (NSCLC) resistance to KRAS G12C inhibitors by dual inhibition of hepatocyte growth factor receptor (MET) and V-ATPase

Rapid reactivation of KRAS guanosine triphosphate (GTP) resistance to covalent KRAS G12C inhibitors in NSCLC cells is possibly associated with lower expression of regulator RGS3 GTPase-activating protein. Enhanced MET expression is essential for anchorage-independent growth of KRAS-mutant NSCLC cells. Increased MET levels have been reported in sotorasib resistant cells. Establishment of sotorasib and trametinib resistant H358, H23, A549, H460 NSCLC cells lines were performed. In vitro growth inhibitory assays determined cell viability after 3-day treatment with omeprazole, tepotinib or combination. Western blotting was carried out with antibodies specific for phospho-AKT, phospho-ERK1/2, phospho-MET, enolase 1 (ENO1), RGS3, and actin. In vivo tumor growth inhibitory assay was performed with H358 in female BALB/c-Nude mice. Pretreatment with omeprazole + tepotinib shows broad-spectrum tumor shrinkage in KRAS G12C sensitive and resistant to sotorasib (H358, H23) and in KRAS non-G12C cell lines (A549, H460). Synergism was sustained with HGF stimulation in H358 resistant cell line (CI = 0.790). Colony formation assay shows similar growth inhibition in KRAS G12C and non G12C parental and resistant. In H358 xenograft mice model tumors were efficiently suppressed with omeprazole+tepotinib combination. Cell signaling analysis revealed that the combination shut down crosstalk between MET and Wnt signaling by downregulating enolase 1 and lipoprotein receptor-related protein (LRP5/6), enhancing RGS3 expression. Co-treatment with v-ATPase and MET inhibitors is active in KRAS-mutant G12C and non-G12C NSCLC parental and resistant to covalent KRAS G12C inhibitors and MEK inhibitors. Intracellular signaling identifies interplay within MET and Wnt pathway and glycolysis inhibition. A clinical protocol was set up to test ex-vivo (patient derived lung tumor organoid fresh biopsy collection) in KRAS-mutant NSCLC patients.