Glesatinib Exhibits Antitumor Activity in Lung Cancer Models and Patients Harboring Exon 14 Mutations and Overcomes Mutation-mediated Resistance to Type I MET Inhibitors in Nonclinical Models.

exon 14 deletion (ex14 del) mutations represent a novel class of non-small cell lung cancer (NSCLC) driver mutations. We evaluated glesatinib, a spectrum-selective MET inhibitor exhibiting a type II binding mode, in ex14 del-positive nonclinical models and NSCLC patients and assessed its ability to overcome resistance to type I MET inhibitors. As most MET inhibitors in clinical development bind the active site with a type I binding mode, we investigated mechanisms of acquired resistance to each MET inhibitor class utilizing and models and in glesatinib clinical trials. Glesatinib inhibited MET signaling, demonstrated marked regression of ex14 del-driven patient-derived xenografts, and demonstrated a durable RECIST partial response in a ex14 del mutation-positive patient enrolled on a glesatinib clinical trial. Prolonged treatment of nonclinical models with selected MET inhibitors resulted in differences in resistance kinetics and mutations within the activation loop (i.e., D1228N, Y1230C/H) that conferred resistance to type I MET inhibitors, but remained sensitive to glesatinib. models exhibiting ex14 del/A-loop double mutations and resistance to type I inhibitors exhibited a marked response to glesatinib. Finally, a ex14 del mutation-positive NSCLC patient who responded to crizotinib but later relapsed, demonstrated a mixed response to glesatinib including reduction in size of a Y1230H mutation-positive liver metastasis and concurrent loss of detection of this mutation in plasma DNA. Together, these data demonstrate that glesatinib exhibits a distinct mechanism of target inhibition and can overcome resistance to type I MET inhibitors. .