Preclinical Development of U3-1784, a Novel FGFR4 Antibody Against Cancer, and Avoidance of Its On-target Toxicity.

The FGFR4/FGF19 signaling axis is overactivated in 20% of liver tumors and currently represents a promising targetable signaling mechanism in this cancer type. However, blocking FGFR4 or FGF19 has proven challenging due to its physiological role in suppressing bile acid synthesis which leads to increased toxic bile acid plasma levels upon FGFR4 inhibition. An FGFR4-targeting antibody, U3-1784, was generated in order to investigate its suitability as a cancer treatment without major side effects.U3-1784 is a high-affinity fully human antibody that was obtained by phage display technology and specifically binds to FGFR4. The antibody inhibits cell signaling by competing with various FGFs for their FGFR4 binding site thereby inhibiting receptor activation and downstream signaling via FRS2 and Erk. The inhibitory effect on tumor growth was investigated in 10 different liver cancer models in vivo The antibody specifically slowed tumor growth of models overexpressing FGF19 by up to 90% whereas tumor growth of models not expressing FGF19 was unaffected. In cynomolgus monkeys, intravenous injection of U3-1784 caused elevated serum bile acid and liver enzyme levels indicating potential liver damage. These effects could be completely prevented by the concomitant oral treatment with the bile acid sequestrant colestyramine, which binds and eliminates bile acids in the gut. These results offer a new biomarker-driven treatment modality in liver cancer without toxicity and they suggest a general strategy for avoiding adverse events with FGFR4 inhibitors.

[Therapeutic efficacy of levofloxacin against a model of replicable Legionella pneumophila lung infection in DBA/2 mice].

The in vitro and in vivo antibacterial activities of levofloxacin (LVFX), a quinolone antibacterial, against clinically isolated Legionella pneumophila were investigated in comparison with those of existing antimicrobial agents approved for legionnaires disease. The minimum inhibitory concentrations (MICs) of the agents against 42 strains of L. pneumophila isolated in Japan were determined using agar dilution methods with buffered starch yeast extract agar. MIC90 of LVFX was 0.03 microg/ml and this activity was similar to ciprofloxacin and pazufloxacin, and higher than telithromycin and minocycline. Therapeutic efficacy of LVFX was studied against a pneumonia model induced by intranasal of L. pneumophila strain suzuki serogoup 1 in DBA/2 mice. Therapeutic doses in mice were selected that would closely match human exposure profile, area under the concentration-time curve (AUC) for a human oral dose of LVFX at 500 mg once a day. LVFX decreased significantly the bacterial burden in the lungs from the next day of commencing treatment. These results, including in vitro antibacterial activity against clinical isolates and therapeutic efficacy of a humanized dosing regimen, provide good evidence to support the use of LVFX at 500 mg once a day for treating patient with legionnaires disease.

Olfactory epithelium as a novel toxic target following an intravenous administration of vincristine to mice.

To delineate morphological characteristics of olfactory lesions induced by vincristine (VCR), a vinca alkaloid derivative with antitumor activity, male BALB/c mice were given a single intravenous injection of 1.95 mg/kg, an estimated 10% lethal dose (designated as day 1). The animals were serially sacrificed on days 2, 3, 5, 10, 15 and 60, and the nasal mucosa was examined histopathologically. Cell death was noted in the olfactory epithelia adjacent to the respiratory epithelia from days 2 to 5. Inflammatory responses were not detected throughout the observation periods. Cell death was identified as apoptotic by the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay and electron microscopy. Mitotic figures and proliferating cell nuclear antigen (PCNA)-positive reactions were diffusely scattered in both the basal and sensory cells. On days 10 or after, no prominent histological abnormalities were noted in the olfactory epithelia, which suggests the aforementioned lesions were completely recovered. These results demonstrate that it is essential to perform histopathological evaluation of the nasal mucosa during an early preclinical stage for novel antitumor drugs, since olfactory lesions due to the certain compounds like VCR may not be detected by any other procedure.