Fibroblast growth factor receptor (FGFR) signaling is deregulated in many human cancers and FGFR is considered a valid target in FGFR-deregulated tumors. Here we examine the preclinical profile of futibatinib (TAS-120; 1-[(3S)-[4-amino-3-[(3,5-dimethoxyphenyl)ethynyl]-1Hpyrazolo[3,4-d] pyrimidin-1-yl]-1-pyrrolidinyl]-2-propen-1-one), a structurally novel, irreversible FGFR1-4 inhibitor. Among a panel of 296 human kinases, futibatinib selectively inhibited FGFR1-4 with half-maximal inhibitory concentration (IC 50) values of 1.4-3.7 nmol/L. Futibatinib covalently bound the FGFR kinase domain, inhibiting FGFR phosphorylation and, in turn, downstream signaling in FGFR-deregulated tumor cell lines. Futibatinib exhibited potent, selective growth inhibition of several tumor cell lines (gastric, lung, multiple myeloma, bladder, endometrial, and breast) harboring various FGFR genomic aberrations. Oral administration of futibatinib led to significant dose-dependent tumor reduction in various FGFR-driven human tumor xenograft models and tumor reduction was associated with sustained FGFR inhibition, which was proportional to the administered dose. The frequency of appearance of drug-resistant clones was lower with futibatinib than a reversible ATP-competitive FGFR inhibitor, and futibatinib inhibited several drug-resistant FGFR2 mutants, including the FGFR2 V565I/L gatekeeper mutants, with greater potency than any reversible FGFR inhibitors tested (IC 50 , 1.3-50.6 nmol/L). These results indicate that futibatinib is a novel orally available, potent, selective, and irreversible inhibitor of FGFR1-4 with a broad spectrum of antitumor activity in cell lines and xenograft models. These findings provide a strong rationale for testing futibatinib in patients with tumors oncogenically driven by FGFR genomic aberrations, with phase 1-3 trials ongoing. Research.

NEDD8-activating enzyme (NAE) is an essential E1 enzyme of the NEDD8 conjugation (neddylation) pathway, which controls cancer cell growth and survival through activation of cullin-RING ubiquitin ligase complexes (CRL). In this study, we describe the preclinical profile of a novel, highly potent, and selective NAE inhibitor, TAS4464. TAS4464 selectively inhibited NAE relative to the other E1s UAE and SAE. TAS4464 treatment inhibited cullin neddylation and subsequently induced the accumulation of CRL substrates such as CDT1, p27, and phosphorylated IkBa in human cancer cell lines. TAS4464 showed greater inhibitory effects than those of the known NAE inhibitor MLN4924 both in enzyme assay and in cells. Cytotoxicity profiling revealed that TAS4464 is highly potent with wide-spread antiproliferative activity not only for cancer cell lines, but also patient-derived tumor cells. TAS4464 showed prolonged target inhibition in human tumor xenograft mouse models; weekly or twice a week TAS4464 administration led to prominent antitumor activity in multiple human tumor xenograft mouse models including both hematologic and solid tumors without marked weight loss. As a conclusion, TAS4464 is the most potent and highly selective NAE inhibitor reported to date, showing superior antitumor activity with prolonged target inhibition. It is, therefore, a promising agent for the treatment of a variety of tumors including both hematologic and solid tumors. These results support the clinical evaluation of TAS4464 in hematologic and solid tumors.

VEGF receptor (VEGFR) signaling plays a key role in tumor angiogenesis. Although some VEGFR signaltargeted drugs have been approved for clinical use, their utility is limited by associated toxicities or resistance to such therapy. To overcome these limitations, we developed TAS-115, a novel VEGFR and hepatocyte growth factor receptor (MET)-targeted kinase inhibitor with an improved safety profile. TAS-115 inhibited the kinase activity of both VEGFR2 and MET and their signal-dependent cell growth as strongly as other known VEGFR or MET inhibitors. On the other hand, kinase selectivity of TAS-115 was more specific than that of sunitinib and TAS-115 produced relatively weak inhibition of growth (GI 50 > 10 mmol/L) in VEGFR signal-or MET signalindependent cells. Furthermore, TAS-115 induced less damage in various normal cells than did other VEGFR inhibitors. These data suggest that TAS-115 is extremely selective and specific, at least in vitro. In in vivo studies, TAS-115 completely suppressed the progression of MET-inactivated tumor by blocking angiogenesis without toxicity when given every day for 6 weeks, even at a serum-saturating dose of TAS-115. The marked selectivity of TAS-115 for kinases and targeted cells was associated with improved tolerability and contributed to the ability to sustain treatment without dose reduction or a washout period. Furthermore, TAS-115 induced marked tumor shrinkage and prolonged survival in MET-amplified human cancer-bearing mice. These data suggest that TAS-115 is a unique VEGFR/MET-targeted inhibitor with improved antitumor efficacy and decreased toxicity. Mol Cancer Ther; 12(12); 2685-96. Ó2013 AACR.

Background: FGFs (fibroblast growth factors) and their receptors (FGFRs) play crucial roles in regulation of cell proliferation, survival, migration and differentiation. The FGFRs are comprised of four subtypes (FGFR1∼4) and their gene abnormalities such as gene amplification, translocation and mutations have been reported in multiple cancers including breast, bladder, lung, gastric, endometrial and multiple myeloma. We have identified a highly potent and selective irreversible FGFR inhibitor, TAS-1201) which inhibits all 4 subtypes of FGFR. In this report, we present the in vitro efficacy of this compound in tumor cells harboring the various FGFR gene abnormalities. In addition, we present the antitumor efficacy and pharmacodynamic (PD) activity of in vivo xenograft models. Materials and Methods: For a growth inhibition assay, various tumor cells with FGFR gene abnormalities were treated with TAS-120 for 3 days, and living cells were determined by using CellTiter-Glo™ which measures cellular ATP. Cellular phosphorylation of FGFR and its inhibition by TAS-120 were assayed using ELISA (R&D Systems) or western blotting method. For analysis of in vivo antitumor efficacy, various tumor cell lines were subcutaneously implanted into the side flank of nude mice. Dosing of compound was started when transplanted tumor size reached > ∼ 200 mm3 and tumor size was measured with digital calipers for the entire treatment period. To confirm target engagement by TAS-120 in human tumor xenograft models, we determined FGFR phosphorylation in tumor as a pharmacodynamic marker. FGFR phoshorylation in tumor was determined by ELISA or western blotting. Results: In a cell proliferation assay, TAS-120 selectively inhibited growth of human cancer cell lines with FGFR gene abnormalities. Growth of cell lines without FGFR abnormalities were not inhibited by TAS-120 treatment. TAS-120 inhibited cellular phosphorylation of FGFR as well as intercellular signaling pathways downstream of FGFR in these cells. In addition, TAS-120 inhibited tumor growth in human tumor xenograft mouse models and FGFR phosphorylation in tumor in a dose-dependent manner. Conclusion: TAS-120 is a highly potent irreversible FGFR inhibitor. It selectively inhibited growth of human cancer cell lines selectively, in a FGFR gene abnormality-dependent manner. In addition, TAS-120 demonstrated tumor growth inhibition in mice xenograft models. PD assays suggested this compound inhibits FGFR activity in human tumor xenograft models. 1) 24th EORTC-NCI-AACR Symposium (2012) abstract #380 & #383 Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A270. Citation Format: Hiroaki Ochiiwa, Hidenori Fujita, Kimihiro Itoh, Hiroshi Sootome, Akihiro Hashimoto, Yayoi Fujioka, Yoko Nakatsuru, Nobuyuki Oda, Kazuhiko Yonekura, Hiroshi Hirai, Teruhiro Utsugi. TAS-120, a highly potent and selective irreversible FGFR inhibitor, is effective in tumors harboring various FGFR gene abnormalities. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A270.