No abstract

BMS-986094, the prodrug of a guanosine nucleotide analogue (2'-C-methylguanosine), was withdrawn from clinical trials due to serious safety issues. Nonclinical investigative studies were conducted as a follow up to evaluate the potential for BMS-986094-related mitochondrial-toxicity. In vitro, BMS-986094 was applied to human hepatoma cells (HepG2 and Huh-7) or cardiomyocytes (hiPSCM) up to 19 days to assess mitochondrial DNA content and specific gene expression. There were no mitochondrial DNA changes at concentrations ≤10 µM. Transcriptional effects, such as reductions in Huh-7 MT-ND1 and MT-ND5 mRNA content and hiPSCM MT-ND1, MT-COXII, and POLRMT protein expression levels, occurred only at cytotoxic concentrations (≥10 µM) suggesting these transcriptional effects were a consequence of the observed toxicity. Additionally, BMS-986094 has a selective weak affinity for inhibition of RNA polymerases as opposed to DNA polymerases. In vivo, BMS-986094 was given orally to cynomolgus monkeys for 3 weeks or 1 month at doses of 15 or 30 mg/kg/day. Samples of heart and kidney were collected for assessment of mitochondrial respiration, mitochondrial DNA content, and levels of high energy substrates. Although pronounced cardiac and renal toxicities were observed in some monkeys at 30 mg/kg/day treated for 3-4 weeks, there were no changes in mitochondrial DNA content or ATP/GTP levels. Collectively, these data suggest that BMS-986094 is not a direct mitochondrial toxicant.

The results of these studies indicated that dasatinib did not induce physiological changes or molecular signatures consistent with PAH when compared to positive controls. Instead, dasatinib induced changes consistent with imatinib. Both dasatinib and imatinib induced biochemical and structural changes consistent with a protective effect for PAH. These data suggest that other factors of unclear etiology contributed to the development of PAH in patients treated with dasatinib.

The objective of this study was to evaluate potential protective effects of vehicles containing d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), which may impact nonclinical safety assessments of oxidative processes. This was achieved by evaluating plasma, liver and adrenal gland concentrations of d-α-tocopheryl succinate (TS) and d-α-tocopherol as well as oxidative status of plasma following oral dosing of TPGS-containing vehicles, intraperitoneal (IP) dosing of TS or ex vivo treatment of blood with H2O2. Male and female rats were dosed orally with formulations containing 5% or 40% TPGS (70 or 550 mg kg(-1) day(-1) TS, respectively) for 1 week. A control group was dosed orally with polyethylene glycol-400 (PEG-400; no vitamin E) and positive control animals received a single 100 mg kg(-1) day(-1) IP injection of TS. Whole blood from untreated animals was treated ex vivo with 5 or 50 mm H(2)O(2), with or without TS (0.5, 5, 50 or 500 μm) or ascorbate (1 mm), for 1 h. Oral TPGS treatments did not affect d-α-tocopherol concentrations in plasma or adrenal glands and caused only transient increases in liver. Concentrations of TS in plasma, liver and adrenal glands were undetectable in control animals, but increased in all other groups. Oral administration of TPGS did not reduce plasma lipid peroxidation in vivo. Substantially greater TS concentrations used ex vivo (100× greater than in vivo) were also unable to reduce lipid peroxidation in H2O2 -treated whole blood. These results provide evidence that administration of oral TPGS vehicles is unlikely to impact nonclinical safety assessments of pharmaceuticals.

Pulmonary arterial hypertension (PAH), defined by increase in mean pulmonary arterial pressure (PAP), results from occlusion or vasoconstriction of the pulmonary veins and can lead to progressive right ventricular failure. The tyrosine kinase inhibitor (TKI) imatinib, indicated for chronic myelogenous leukemia (CML) is being investigated as a potential treatment for PAH, due to its anti-vasoproliferative properties. However, the TKI dasatinib also used for CML is associated with PAH in a small percentage of heavily pre-treated patients although partial or complete reversibility is seen after discontinuation of treatment. Despite the different kinase profiles, studies in rat models of PAH have shown that both TKIs are equally efficacious in reversing functional and structural PAH-related changes. Therefore, nonclinical in vivo (SD rat) and in vitro (human pulmonary artery endothelial cells/smooth muscle cells [hPAEC/hPASM) studies evaluating direct effects of the two TKIs were conducted to understand the potential mechanistic differences for the apparently different clinical effect. The in vivo study explored direct effects of vehicle (80 mM citric acid; control), clinically relevant doses of imatinib and dasatinib (30 or 8 mg/kg/day, oral) and monocrotaline (single i.p. dose, 70 mg/kg; positive control) on PAH-related pulmonary changes in rats (1-month treatment). Monocrotaline reduced nitric oxide (NO; vasodilation) and increased endothelin-1 (ET-1; vasoconstriction) levels in plasma, induced structural changes (perivascular inflammation, EC injury and SMC proliferation) in PA and lungs, and increased (2-5× control) systolic and diastolic PAP and right ventricular pressure. In contrast, both imatinib and dasatinib increased NO in plasma (2.5×), did not any induce PAH-related structural changes (PA or lungs) and did not alter hemodynamic function compared to controls. The in vitro hPAEC/PASM co-culture model demonstrated that imatinib and dasatinib at clinically relevant (Cmax) concentrations increased NO and decreased ET-1 protein and mRNA. Our results demonstrate that dasatinib, as imatinib, does not have the potential to directly induce PAH-related changes in vivo or in vitro. In addition, both molecules induce biochemical changes in vivo and in vitro consistent with a protective effect on PAP. Citation Format: Mausumee Guha, James Hennan, Julia Li, Damir Simic, Jochen Woiche, Bethany Baumgart, Thomas Sanderson, Michael Graziano, Roderick Bunch. In vitro and in vivo evaluation of dasatinib and imatinib on physiological parameters of pulmonary arterial hypertension . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2426. doi:10.1158/1538-7445.AM2013-2426 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.