Phase I dose escalation study of telatinib, a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 2 and 3, platelet-derived growth factor receptor beta, and c-Kit, in patients with advanced or metastatic solid tumors.

PURPOSE: Telatinib (BAY 57-9352) is an orally available tyrosine kinase inhibitor of vascular endothelial growth factor receptor (VEGFR) -2, VEGFR-3, platelet-derived growth factor receptor-beta, and c-Kit. This phase I dose escalation study was conducted to evaluate the safety and tolerability of telatinib, with additional pharmacokinetic, pharmacodynamic, and efficacy assessments. PATIENTS AND METHODS: Patients with solid tumors refractory to standard therapies or with no standard therapy available were enrolled. Doses of continuously administered telatinib were escalated from 20 mg once daily to 1,500 mg twice daily. RESULTS: Fifty-three patients were enrolled. Most frequently observed drug-related adverse events were nausea (26.4%; grade >or= 3, 0%) and hypertension (20.8%; grade 3, 11.3%; grade 4, 0%). Two dose-limiting toxicities were observed: one poorly controlled hypertension (600 mg twice daily), and one grade 2 weight loss, anorexia, and fatigue (1,500 mg twice daily). A formal maximum-tolerated dose was not reached. Telatinib was rapidly absorbed, with median time to peak concentration (t(max)) lower than 3 hours after dose. A nearly dose-proportional increase in exposure was observed with substantial variability. Telatinib half-life averaged 5.5 hours. Biomarker analyses showed dose-dependent increase in VEGF levels and decrease in plasma soluble VEGFR-2 levels, with a plateau at 900 mg twice daily. A decrease in tumor blood flow (K(trans) and IAUC(60)) was observed with dynamic contrast-enhanced magnetic resonance imaging. Best tumor response was stable disease, observed in 50.9% of patients. CONCLUSION: Telatinib was safe and well tolerated up to 1,500 mg twice daily. Based on pharmacodynamic and pharmacokinetic end points, telatinib 900 mg twice daily is the recommended dose for subsequent phase II studies.

Differential inhibition of inducible T cell cytokine secretion by potent iron chelators.

Effector functions and proliferation of T helper (Th) cells are influenced by cytokines in the environment. Th1 cells respond to a synergistic effect of interleukin-12 (IL-12) and interleukin-18 (IL-18) to secrete interferon-gamma (IFN-gamma). In contrast, Th2 cells respond to interleukin-4 (IL-4) to secrete IL-4, interleukin-13 (IL-13), interleukin-5 (IL-5), and interleukin-10 (IL-10). The authors were interested in identifying nonpeptide inhibitors of the Th1 response selective for the IL-12/IL-18-mediated secretion of IFN-gamma while leaving the IL-4-mediated Th2 cytokine secretion relatively intact. The authors established a screening protocol using human peripheral blood mononuclear cells (PBMCs) and identified the hydrazino anthranilate compound 1 as a potent inhibitor of IL-12/IL-18-mediated IFN-gamma secretion from CD3(+) cells with an IC(50) around 200 nM. The inhibitor was specific because it had virtually no effect on IL-4-mediated IL-13 release from the same population of cells. Further work established that compound 1 was a potent intracellular iron chelator that inhibited both IL-12/IL-18- and IL-4-mediated T cell proliferation. Iron chelation affects multiple cellular pathways in T cells. Thus, the IL-12/IL-18-mediated proliferation and IFN-gamma secretion are very sensitive to intracellular iron concentration. However, the IL-4-mediated IL-13 secretion does not correlate with proliferation and is partially resistant to potent iron chelation.