Abstract 788: A novel, potent and selective pan-Trk inhibitor ONO-5390556, demonstrates therapeutic efficacy in cancer cells harboring the TrkA rearrangement
Authors: Tsukamoto Kohki , Yoshizawa Toshio , Kozaki Ryohei , Kawabata Kazuhito 
Published: August 2015

Abstract
Purpose: Fusion genes including EML4-ALK, which have been recognized as driver mutations in cancers, encode chimeric proteins with constitutive kinase activity, which promote tumor cell survival. Patients with ALK-Positive Non-Small Cell Lung Cancer have demonstrated remarkable clinical responses to the ALK tyrosine kinase inhibitor, Crizotinib. TrkA/NTRK1,TrkB/NTRK2 and TrkC/NTRK3 belong to the neurotrophic tyrosine kinase receptor family. Signals from Trk receptors play a role in neuronal survival and differentiation through several signal cascades. Recently, oncogenic rearrangements of TrkA, B and C genes were identified in a variety of cancers, including lung adenocarcinoma, colorectal cancer, glioblastoma and acute myeloid leukemia. Therefore, the oncogenic Trk fusion proteins are attractive therapeutic targets that warrant further investigation. ONO-5390556 is a novel, potent and selective pan-Trk inhibitor with an IC50 in the low nM range. We evaluated the anti-tumor activity of ONO-5390556 against TrkA rearranged cancer cells in vitro and in vivo.
Methods: Phospho-proteins were detected by Western blotting. In a proliferation assay, cells were treated with ONO-5390556 at concentrations ranging from 0.03 to 100 nM for 72h. Cell viability was determined by WST-8 assay. In a KM12 xenograft model, cells were implanted subcutaneously into female nude mice. Mice were randomized when the mean tumor volume was 100-200 mm3. ONO-5390556 was administered orally with doses ranging between 0.1 and 1 mg/kg twice daily (BD) for 14 days. Tumor volumes were measured twice a week after initiation of treatment, and tumor volumes were determined using the formula volume ( = width2 x length)/2.
Results: ONO-5390556 inhibited TrkA autophosphorylation and cell proliferation in BaF3 murine pro B cell lines transformed with a TrkA fusion gene with an IC50 of 0.4 and 0.2 nM, respectively. Similarly, in KM12, human colorectal cancer cell lines harboring TPM3-TrkA fusions, both the autophosphorylation of TrkA and the cell proliferation were strongly inhibited by ONO-5390556 with an IC50 of 0.2 and 0.3 nM, respectively. Interestingly, TrkA autophosphorylation remained strongly inhibited even 24 hours after a washout of ONO-5390556 in KM12, which suggests ONO-5390556 has tight-binding properties. In the KM12 Xenograft model, treatment with ONO-5390556 at doses of 0.1, 0.3 and 1mg (BD) for 14 days resulted in a dose-dependent inhibition of tumor growth with Tumor Growth Inhibition (TGI) of 48.0, 89.2 and 95.6%, respectively.
Conclusion: ONO-5390556 is a highly potent and selective pan-Trk inhibitor with evidence of an excellent anti-tumor activity in cancer cells harboring the TrkA rearrangement. These preliminary results suggest that ONO-5390556 may be an effective therapeutic option in a wide variety of cancers including lung and colorectal cancers with Trk rearrangements.
Citation Format: Kohki Tsukamoto, Toshio Yoshizawa, Ryohei Kozaki, Kazuhito Kawabata. A novel, potent and selective pan-Trk inhibitor ONO-5390556, demonstrates therapeutic efficacy in cancer cells harboring the TrkA rearrangement. [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 788. doi:10.1158/1538-7445.AM2015-788