The FGF receptors (FGFR) are tyrosine kinases that are constitutively activated in a subset of tumors by genetic alterations such as gene amplifications, point mutations, or chromosomal translocations/rearrange-

The fibroblast growth factor receptor (FGFR) family of receptor tyrosine kinases regulates multiple biological processes, such as cell proliferation, migration, apoptosis, and differentiation. Various genetic alterations that drive activation of the receptors and the pathway are associated with tumor growth and survival; therefore, the FGFR family represents an attractive therapeutic target for treating cancer. Here, we report the discovery and the pharmacological profiles of 8 (CH5183284/Debio 1347), an orally available and selective inhibitor of FGFR1, FGFR2, and FGFR3. The chemical modifications, which were guided by 3D-modeling analyses of the inhibitor and FGFRs, led to identifying an inhibitor that is selective to FGFR1, FGFR2, and FGFR3. In in vitro studies and xenograft models in mice, 8 shows antitumor activity against cancer cell lines that harbor genetically altered FGFRs. These results support the potential therapeutic use of 8 as a new anticancer agent.

-Anti-angiogenic drugs that target Vascular Endothelial Growth Factor (VEGF) signaling pathways caused hypertension as an adverse effect in clinical studies. Since the hypertension may limit the benefit provided for patients, the demand for non-clinical research that predicts the clinical risk of the hypertension has risen greatly. To clarify whether non-clinical research using rats can appropriately estimate the clinical risk of hypertension caused by VEGF signal inhibitors, we investigated the hemodynamic effects and pharmacokinetics (PK) of the VEGF signal inhibitors cediranib (0.1, 3, and 10 mg/kg), sunitinib (5, 10, and 40 mg/kg), and sorafenib (0.1, 1, and 5 mg/kg) in telemetered rats and examined the correlation between the non-clinical and the clinical hypertensive effect. The VEGF signal inhibitors significantly elevated blood pressure (BP) in rats within a few days of the initiation of dosing, and levels recovered after dosing ended. The trend of the hypertension was similar to that in clinical studies. We found that the AUC at which BP significantly increased by approximately 10 mmHg in rats was comparable to the clinical AUC at which moderate to severe hypertension occurred. These results represent correlations between the non-clinical and the clinical hypertensive effect of VEGF signal inhibitors, suggesting that non-clinical research using telemetered rats would be an effective approach to predict the clinical risk of hypertension caused by VEGF signal inhibitors.

We used motion field imaging to characterize the conduction and contraction of a sheet of cardiomyocytes derived from human induced pluripotent stem cells (hiPS-CMs). A hiPS-CMs sheet of 2.8 mm × 2.8 mm allowed us to simultaneously measure the conduction and the contraction properties in the same cells. Pharmacological responses in the hiPS-CMs of four typical cardiac functional modulators, Na channel blocker (lidocaine), Ca channel blocker (diltiazem), gap-junction inhibitor (carbenoxolone), and β-adrenergic stimulator (isoproterenol), were investigated, and the results were compared to those found using the isolated guinea-pig heart model perfused by the Langendorff method. The conduction speed of excitation waves in hiPS-CMs was decreased by lidocaine, diltiazem, and carbenoxolone, and increased by isoproterenol, and these results were in accordance with the changes in the conduction parameters of electrocardiogram (QRS duration, PR interval, and P duration) in the Langendorff guinea-pig heart model. The maximum speeds for contraction and relaxation, which respectively represent the contraction and relaxation kinetics of hiPS-CMs, were decreased by lidocaine and diltiazem, and increased by isoproterenol. These results also corresponded to alterations in the contractile and relaxation parameters found by measuring left ventricular pressure (LVdP/dt and LVdP/dt) in the Langendorff guinea-pig heart model. From these lines of evidence, it was suggested that hiPS-CMs enable us to evaluate the cardiac toxicities associated with conduction disturbance or contractile dysfunction, and thereby would be useful as an integrated assessment of cardiac function.

Abstract. Our previous study has shown that the corrected QT (QTc) interval of the electrocardiogram is longer during the dark period than during the light period in telemetered common marmosets. In the present study, we investigated the involvement of sympathetic and parasympathetic nervous activities in the changes of QTc interval associated with the light-dark cycle. Telemetry transmitters were implanted in six common marmosets to continuously record the electrocardiogram. The QT intervals obtained were corrected for the RR interval by applying individual probabilistic QT-rate correction formulae. Power spectral analysis of heart rate variability was performed to quantify each autonomic nervous function. Changes in QTc intervals and autonomic nervous tones were associated with the light-dark cycle. Parasympathetic nervous activity and QTc intervals significantly increased by approximately 10 ms during the dark period. Atropine, a muscarinic receptor antagonist, suppressed the increased parasympathetic tone and QTc prolongation during the dark period. In contrast, propranolol, a β-adrenoceptor antagonist, decreased the sympathetic activity and increased QTc intervals during the light period. These results suggest that the parasympathetic nerve functions prolong QTc intervals during the dark period, while the sympathetic nerve functions shorten them during the light period in common marmosets.

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-The aims of this study were to determine a suitable method to correct the ventricular repolarization period against the RR interval in isolated perfused Langendorff guinea pig heart and to clarify the reliability of this model using several drugs. QT and RR intervals from an electrocardiogram and the epicardial monophasic action potential duration (MAP 90 ) were measured. Two drugs clinically known to be QT-prolonging (E-4031, moxifloxacin) and two known to be non-QT-prolonging (verapamil, zatebradine) were used for the study. To determine a method of correcting the ventricular repolarization period against RR interval, heart rates were slowed with 0.3 µM zatebradine, a specific bradycardiac agent, and then accelerated with atrial pacing to obtain a wide range of MAP 90 /RR relationships. An exponential rate-correction model elicited the most appropriate algorithm for the relationship among the four models tested. Based on linear regression analysis, the exponential showed superior dissociation of corrected MAP 90 s against RR intervals than generic Bazett's and Fridericia's formulae. E-4031 and moxifloxacin prolonged the corrected QT (QTc) intervals and MAP 90 under atrial pacing at a cycle length of 0.25 sec (MAP 90(pacing) ) dose-dependently; verapamil and zatebradine failed to prolong them, indicating that the reliability of this model was excellent. MAP 90(pacing) prolongation by moxifloxacin, the positive compound in the clinical "Thorough QT/QTc Study", was seen at around QTc-prolonging concentrations in clinic, suggesting that the sensitivity would be appropriate for QT evaluation. We therefore concluded that the isolated guinea pig heart model is sufficiently sensitive and useful for assessing the potential QT prolongation of drugs.

The fibroblast growth factor receptors (FGFR) are tyrosine kinases that are constitutively activated in a subset of tumors by genetic alterations such as gene amplification, point mutation, or chromosomal translocation/rearrangement. Recently, small-molecule inhibitors that can inhibit the FGFR family as well as the VEGFR or PDGFR family showed some clinical benefits in FGFR genetically altered patient populations. However, to achieve more potent and prolonged efficacy in such populations, a selective FGFR inhibitor is still needed. Here, we report identifying CH5183284/Debio 1347, a selective and orally available FGFR1, FGFR2, and FGFR3 inhibitor that has a unique chemical scaffold as a FGFR inhibitor. By interacting with unique residues in the ATP binding site of FGFR1, FGFR2, or FGFR3, CH5183284/Debio 1347 selectively inhibits FGFR1, FGFR2, and FGFR3 (IC50: 9.3 nM, 7.6 nM, and 22 nM), but does not effectively inhibit FGFR4 (IC50: 290 nM ), KDR (IC50: 2,100 nM) or other 34 kinases. At 100 nM, CH5183284/Debio 1347 only binds to 5 kinases in the KinomeScan panel, including FGFR1, FGFR2, and FGFR3. Consistent with its high selectivity for FGFR enzymes, CH5183284/Debio 1347 does not lead to significant changes in blood pressure in telemetry-instrumented rats. In addition, CH5183284/Debio 1347 has a preferential antitumor activity against cancer cells with FGFR genetic alterations in a panel of 327 cancer cell lines. Among them, 4 cancer cell lines have copy number variations (CNV) of FGFR1 (>2.2 fold), 2 cancer cell lines have chromosomal translocation of FGFR1 (FGFR1OP-FGFR1), 6 cancer cell lines have CNV of FGFR2 (>2.2 fold), 3 cancer cell lines have point mutation of FGFR2 (S252W, K310R, N549K), 3 cancer cell lines have chromosomal translocation of FGFR3 (FGFR3-TACC3, FGFR3-BAIAP2L1), and 2 cancer cell lines have point mutation of FGFR3 (S249C, Y373C). This preferential efficacy against cancers harboring genetic alterations in FGFR was also confirmed in mouse xenograft studies. These findings warrant further investigation of CH5183284/Debio 1347 in patients harboring FGFR genetic alterations. Clinical studies have been initiated. Citation Format: Yoshito Nakanishi, Nukinori Akiyama, Toshiyuki Tsukaguchi, Yukako Tachibana-Kondo, Toshihiko Fujii, Kiyoaki Sakata, Hitoshi Sase, Takehito Isobe, Yasuko Sato, Kenji Morikami, Hidetoshi Shindoh, Toshiyuki Mio, Hirosato Ebiike, Naoki Taka, Yuko Aoki, Nobuya Ishii. FGFR genetic alterations as a potential predictor of the sensitivity to CH5183284/Debio 1347, a selective FGFR inhibitor with a novel chemical scaffold. [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 2729. doi:10.1158/1538-7445.AM2014-2729