Abstract LB-239: Inhibition of MET/RON in lung cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Introduction: Lung cancer can be a heterogeneous group of disorders. We have identified that the MET receptor tyrosine kinase is overexpressed, mutated, and/or amplified in various subsets of lung cancer. Several clinical trials of MET inhibitors that are underway have documented cases of acquired resistance. Based on evidence that the RON tyrosine kinase receptor (family member of MET receptor) can also be overexpressed in NSCLC, we determined the effect of sequential and concurrent inhibition of MET and RON with gene silencing. We identified that both MET and RON gene silencing led to inhibition of signal transduction, but that the combination was more effective. We evaluated the potent MET/RON dual kinase inhibitor LY2801653 in this setting and found it to be more efficacious than the MET/ALK/RON/ROS inhibitor crizotinib with a distinct pattern of changes in downstream signaling. Using the protein phosphorylation detection platform PamGene®, we found that inhibition of MET and RON was associated with decreased phosphorylation of CBL, PI3K and STAT3. A systematic analysis of the PamGene® data allowed us to define abnormalities of the signal transduction pathways. We further report that LY2801653 also has biological and tumor inhibitory effect both in vitro and in vivo. In mouse flank and orthotopic lung xenografts of NSCLC, LY2801653 decreased tumor growth, dramatically inhibiting mitotic events and angiogenesis.. Taken together, our results argued that specific targeting of the MET/RON kinases could provide robust inhibition of cell proliferation and tumor growth in multiple in vitro and in vivo models of NSCLC. These findings offer a robust preclinical proof of concept for MET/RON targeting by LY2801653 as a promising small molecule treatment modality. Methods: LY2801653 was provided by Eli Lilly and Company (Indianapolis, IN). NSCLC cell lines purchased from ATCC were utilized to conduct in vitro and in vivo studies. Cell proliferation assays were performed using MTT, standard immunoblot assays and the high-throughput protein phosphorylation detection platform PamGene® was used to demonstrate phosphorylation events. To determine drug effects in vivo, the mouse flank xenograft model and an orthotopic lung tumor model was used. In the orthotopic model, tumor progression was monitored by bioluminescence using Xenogen IVIS®. Results: We have reported that LY2801653 specifically inhibited proliferation of NSCLC cell lines at IC50 as low as 6-600 nM with inhibition of phosphorylation in downstream signaling of MET/RON. The PamGene® platform also showed a network of downstream signaling molecules affected by MET/RON inhibition, such as CBL, PI3K and STAT3. We further report that LY2801653 also has tumor growth inhibitory effects in mouse xenografts and dramatic effects on mitosis and angiogenesis. Conclusions: Specific inhibition of MET/RON by a small molecule inhibitor LY2801653 was able to abrogate cell proliferation, tumor growth, as well as affect downstream signal transduction of MET/RON in NSCLC. These results demonstrate the promising therapeutic potential of LY2801653 in treating lung cancer. Citation Format: Rifat Hasina, Ichiro Kawada, Qudsia Arif, Jeffrey Mueller, Aliya N. Husain, Everett E. Vokes, Ravi Salgia. Inhibition of MET/RON in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-239. doi:10.1158/1538-7445.AM2014-LB-239