ABSTRACT
Merestinib is an oral multi-kinase inhibitor targeting a limited number of oncokinases including MET, AXL, RON and MKNK1/2. Here, we report that merestinib inhibits neurotrophic receptor tyrosine kinases NTRK1/2/3 which are oncogenic drivers in tumors bearing NTRK fusion resulting from chromosomal rearrangements. Merestinib is shown to be a type II NTRK1 kinase inhibitor as determined by x-ray crystallography. In KM-12 cells harboring TPM3-NTRK1 fusion, merestinib exhibits potent p-NTRK1 inhibition in vitro by western blot and elicits an anti-proliferative response in two- and three-dimensional growth. Merestinib treatment demonstrated profound tumor growth inhibition in in vivo cancer models harboring either a TPM3-NTRK1 or an ETV6-NTRK3 gene fusion. To recapitulate resistance observed from type I NTRK kinase inhibitors entrectinib and larotrectinib, we generated NIH-3T3 cells exogenously expressing TPM3-NTRK1 wild-type, or acquired mutations G595R and G667C in vitro and in vivo. Merestinib blocks tumor growth of both wild-type and mutant G667C TPM3-NTRK1 expressing NIH-3T3 cell-derived tumors. These preclinical data support the clinical evaluation of merestinib, a type II NTRK kinase inhibitor (NCT02920996), both in treatment naïve patients and in patients progressed on type I NTRK kinase inhibitors with acquired secondary G667C mutation in NTRK fusion bearing tumors.
ABSTRACT
BACKGROUND: LY2584702 tosylate (hereafter referred to as LY2584702) is a potent, highly selective adenosine triphosphate (ATP) competitive inhibitor against p70 S6 kinase, a downstream component of the phosphatidylinositol-3-kinase signalling pathway which regulates cell proliferation and survival. LY2584702 exhibited anti-tumour activity in preclinical analysis. METHODS: Patients with advanced solid tumours were treated with LY2584702 orally on a 28-day cycle until the criteria for maximum tolerated dose (MTD) were met. Skin biopsies were collected for pharmacodynamic analysis, and levels of phospho-S6 protein were examined. The primary objective was to determine a phase II dose and schedule with secondary objectives of observing safety and tolerability. Dose escalation was based upon Common Terminology Criteria for Adverse Events Version 3.0. RESULTS: Thirty-four patients were enrolled onto this phase I study and treated with LY2584702 on a QD (once-daily) or BID (twice-daily) dosing schedule. Part A dose escalation (n=22) began with 300 mg BID (n=2). Due to toxicity, this was scaled back to doses of 25mg (n=3), 50 mg (n=8), 100mg (n=3), and 200 mg (n=6) QD. Part B dose escalation (n=12) included 50 mg (n=3), 75 mg (n=3), and 100 mg (n=6) BID. Seven patients experienced dose-limiting toxicity (DLT). All DLTs were Grade 3 and included vomiting, increased lipase, nausea, hypophosphataemia, fatigue and pancreatitis. CONCLUSION: The MTD was determined to be 75 mg BID or 100mg QD. No responses were observed at these levels. Pharmacokinetic analysis revealed substantial variability in exposure and determined that LY2584702 treatment was not dose proportional with increasing dose.
