Abstract 2568: S49076, a MET, AXL, FGFR inhibitor, potentiates radiation therapy in subcutaneous and orthotopic models of lung cancer

Abstract

Abstract S49076 is an oral ATP-competitive inhibitor of the receptor tyrosine kinases MET, AXL, and FGFR1-3 currently in phase I/II clinical development in patients with advanced solid tumors. Here, we investigated the effect of S49076 on both MET- and non-MET- dependent cell lines alone and in association with ionizing radiation (IR) both in vitro and in vivo. We performed proliferation and clonogenic survival assays using the low MET-expressing H460 and A549 non-small-cell lung cancer (NSCLC) cell lines, the high MET-expressing H441 NSCLC cell line and the MET-dependent GTL16 gastric cancer cell line. Activity against the MET receptor and Aurora B kinase was assessed by analyzing the phosphorylation status of MET Tyr1234/1235 and Histone H3 Ser10 residues. Pharmacologic and RNA interference approaches against Aurora B and MET were used to determine the molecular mechanism of the cell response to S49076. S49076 inhibited MET activity in the nanomolar range (1 - 100 nM). At higher, but still clinically-relevant concentrations (0.5 - 1 μM), S49076 was also found to inhibit Aurora B kinase activity in all cell lines tested. In non MET-dependent cell lines, the antiproliferative and anti-clonogenic effects of the drug correlated with its activity against Aurora B, whereas in the MET-dependent cell line, these effects could be attributed to direct inhibition of the MET receptor. When treatment with S49076 was combined with IR, an enhancement of IR effects was observed in all cell lines tested in vitro. In vivo, a significant growth delay of subcutaneous tumors was observed at 50 mg/kg bid oral S49076 in non-MET dependent models and at 3 mg/kg bid oral S49076 in the GTL16 MET-dependent model. For non MET-dependent models, immunohistochemistry revealed that treatment with S49076 reduced Histone H3 phosphorylation on Ser10. This is consistent with the finding that S49076 concentrations above 1 μM were attained in the tumors, as determined by LC-MS/MS analysis. In all tumors tested, S49076 treatment significantly delayed tumor growth when combined to a fractionated IR (4 fractions of 2.5 Gy) compared to IR alone. An orthotopic model of lung cancer using luciferase-expressing H460 NSCLC cells was also used to evaluate the combination of S49076 (50mg/kg bid) and locally fractionated thoracic IR (4*2.5 Gy). In this model, the median survival after cell implantation was 22 days for control mice, 29.5 and 29 days for S49076 treated and irradiated mice respectively and 41 days for mice receiving the combined treatment (p<0.002 for combined treatment versus the irradiated arm or the S49076 treated arm). Our findings indicate that S49076 improves the efficacy of radiotherapy in both MET- and non-MET- dependent cell, supporting the use of combined treatment with S49076 and radiation in clinical trials without patient selection. Citation Format: Céline Clémenson, Cyrus Chargari, Michele Mondini, Charles Ferté, Winchygn Liu, Mike Burbridge, Valérie Cattan, Anne Jacquet-Bescond, Eric Deutsch. S49076, a MET, AXL, FGFR inhibitor, potentiates radiation therapy in subcutaneous and orthotopic models of lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2568. doi:10.1158/1538-7445.AM2015-2568