Mutations within the catalytic domain of the histone methyltransferase EZH2 have been identified in subsets of patients with non-Hodgkin lymphoma (NHL). These genetic alterations are hypothesized to confer an oncogenic dependency on EZH2 enzymatic activity in these cancers. We have previously reported the discovery of EPZ005678 and EPZ-6438, potent and selective S-adenosyl-methionine-competitive small molecule inhibitors of EZH2. Although both compounds are similar with respect to their mechanism of action and selectivity, EPZ-6438 possesses superior potency and drug-like properties, including good oral bioavailability in animals. Here, we characterize the activity of EPZ-6438 in preclinical models of NHL. EPZ-6438 selectively inhibits intracellular lysine 27 of histone H3 (H3K27) methylation in a concentration-and time-dependent manner in both EZH2 wild-type and mutant lymphoma cells. Inhibition of H3K27 trimethylation (H3K27Me3) leads to selective cell killing of human lymphoma cell lines bearing EZH2 catalytic domain point mutations. Treatment of EZH2-mutant NHL xenograft-bearing mice with EPZ-6438 causes dose-dependent tumor growth inhibition, including complete and sustained tumor regressions with correlative diminution of H3K27Me3 levels in tumors and selected normal tissues. Mice dosed orally with EPZ-6438 for 28 days remained tumor free for up to 63 days after stopping compound treatment in two EZH2-mutant xenograft models. These data confirm the dependency of EZH2-mutant NHL on EZH2 activity and portend the utility of EPZ-6438 as a potential treatment for these genetically defined cancers. Mol Cancer Ther; 13(4); 842-54. Ó2014 AACR.

E7080 is an orally active inhibitor of multiple receptor tyrosine kinases including VEGF, FGF and SCF receptors. In this study, we show the inhibitory activity of E7080 against SCF-induced angiogenesis in vitro and tumor growth of SCF-producing human small cell lung carcinoma H146 cells in vivo. E7080 inhibits SCF-driven tube formation of HUVEC, which express SCF receptor, KIT at the IC 50 value of 5.2 nM and it was almost identical for VEGFdriven one (IC 50 5 5.1 nM). To assess the role of SCF/KIT signaling in tumor angiogenesis, we evaluated the effect of imatinib, a selective KIT kinase inhibitor, on tumor growth of H146 cells in nude mice. Imatinib did not show the potent antitumor activity in vitro (IC 50 5 2,200 nM), because H146 cells did not express KIT. However, oral administration of imatinib at 160 mg/kg clearly slowed tumor growth of H146 cells in nude mice, accompanied by decreased microvessel density. Oral administration of E7080 inhibited tumor growth of H146 cells at doses of 30 and 100 mg/kg in a dose-dependent manner and caused tumor regression at 100 mg/kg. While anti-VEGF antibody also slowed tumor growth, it did not cause tumor regression. These results indicate that KIT signaling has a role in tumor angiogenesis of SCF-producing H146 cells, and E7080 causes regression of H146 tumors as a result of antiangiogenic activity mediated by inhibition of both KIT and VEGF receptor signaling. E7080 may provide therapeutic benefits in the treatment of SCF-producing tumors. ' 2007 Wiley-Liss, Inc.

Purpose: Vascular endothelial growth factor (VEGF)-C/VEGF-receptor 3 (VEGF-R3) signal plays a significant role in lymphangiogenesis and tumor metastasis based on its effects on lymphatic vessels. However, little is known about the effect of inhibiting VEGF-R3 on lymphangiogenesis and lymph node metastases using a small-molecule kinase inhibitor. Experimental Design: We evaluated the effect of E7080, a potent inhibitor of both VEGF-R2 and VEGF-R3 kinase, and bevacizumab on lymphangiogenesis and angiogenesis in a mammary fat pad xenograft model of human breast cancer using MDA-MB-231 cells that express excessive amounts of VEGF-C. Lymphangiogenesis was determined by lymphatic vessel density (LVD) and angiogenesis by microvessel density (MVD). Results: In contrast to MDA-MB-435 cells, which expressed a similar amount of VEGF to MDA-MB-231 cells with an undetectable amount of VEGF-C, only MDA-MB-231 exhibited lymphangiogenesis in the primary tumor. E7080 but not bevacizumab significantly decreased LVD within the MDA-MB-231 tumor. E7080 and bevacizumab decreased MVD in both the MDA-MB-231 and MDA-MB-435 models. E7080 significantly suppressed regional lymph nodes and distant lung metastases of MDA-MB-231, whereas bevacizumab significantly inhibited only lung metastases. E7080 also decreased both MVD and LVD within the metastatic nodules at lymph nodes after resection of the primary tumor. Conclusions: Inhibition of VEGF-R3 kinase with E7080 effectively decreased LVD within MDA-MB-231 tumors, which express VEGF-C. Simultaneous inhibition of both VEGF-R2 and VEGF-R3 kinases by E7080 may be a promising new strategy to control regional lymph node and distant lung metastases.

Purpose: Cancer cell microenvironments, including host cells, can critically affect cancer cell behaviors, including drug sensitivity. Although crizotinib, a dual tyrosine kinase inhibitor (TKI) of ALK and Met, shows dramatic effect against EML4-ALK lung cancer cells, these cells can acquire resistance to crizotinib by several mechanisms, including ALK amplification and gatekeeper mutation. We determined whether microenvironmental factors trigger ALK inhibitor resistance in EML4-ALK lung cancer cells.Experimental Design: We tested the effects of ligands produced by endothelial cells and fibroblasts, and the cells themselves, on the susceptibility of EML4-ALK lung cancer cell lines to crizotinib and TAE684, a selective ALK inhibitor active against cells with ALK amplification and gatekeeper mutations, both in vitro and in vivo.Results: EML4-ALK lung cancer cells were highly sensitive to ALK inhibitors. EGF receptor (EGFR) ligands, such as EGF, TGF-a, and HB-EGF, activated EGFR and triggered resistance to crizotinib and TAE684 by transducing bypass survival signaling through Erk1/2 and Akt. Hepatocyte growth factor (HGF) activated Met/Gab1 and triggered resistance to TAE684, but not crizotinib, which inhibits Met. Endothelial cells and fibroblasts, which produce the EGFR ligands and HGF, respectively, decreased the sensitivity of EML4-ALK lung cancer cells to crizotinib and TAE684, respectively. EGFR-TKIs resensitized these cells to crizotinib and Met-TKI to TAE684 even in the presence of EGFR ligands and HGF, respectively.Conclusions: Paracrine receptor activation by ligands from the microenvironment may trigger resistance to ALK inhibitors in EML4-ALK lung cancer cells, suggesting that receptor ligands from microenvironment may be additional targets during treatment with ALK inhibitors. Clin Cancer Res; 18(13); 3592-602. Ó2012 AACR.