Potential for inhibition of checkpoint kinases 1/2 in pulmonary fibrosis and secondary pulmonary hypertension.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterised by exuberant tissue remodelling and associated with high unmet medical needs. Outcomes are even worse when IPF results in secondary pulmonary hypertension (PH). Importantly, exaggerated resistance to cell death, excessive proliferation and enhanced synthetic capacity are key endophenotypes of both fibroblasts and pulmonary artery smooth muscle cells, suggesting shared molecular pathways. Under persistent injury, sustained activation of the DNA damage response (DDR) is integral to the preservation of cells survival and their capacity to proliferate. Checkpoint kinases 1 and 2 (CHK1/2) are key components of the DDR. The objective of this study was to assess the role of CHK1/2 in the development and progression of IPF and IPF+PH. METHODS AND RESULTS: Increased expression of DNA damage markers and CHK1/2 were observed in lungs, remodelled pulmonary arteries and isolated fibroblasts from IPF patients and animal models. Blockade of CHK1/2 expression or activity-induced DNA damage overload and reverted the apoptosis-resistant and fibroproliferative phenotype of disease cells. Moreover, inhibition of CHK1/2 was sufficient to interfere with transforming growth factor beta 1-mediated fibroblast activation. Importantly, pharmacological inhibition of CHK1/2 using LY2606368 attenuated fibrosis and pulmonary vascular remodelling leading to improvement in respiratory mechanics and haemodynamic parameters in two animal models mimicking IPF and IPF+PH. CONCLUSION: This study identifies CHK1/2 as key regulators of lung fibrosis and provides a proof of principle for CHK1/2 inhibition as a potential novel therapeutic option for IPF and IPF+PH.

Preclinical Investigation of Trifluoperazine as a Novel Therapeutic Agent for the Treatment of Pulmonary Arterial Hypertension.

Trifluoperazine (TFP), an antipsychotic drug approved by the Food and Drug Administration, has been show to exhibit anti-cancer effects. Pulmonary arterial hypertension (PAH) is a devastating disease characterized by a progressive obliteration of small pulmonary arteries (PAs) due to exaggerated proliferation and resistance to apoptosis of PA smooth muscle cells (PASMCs). However, the therapeutic potential of TFP for correcting the cancer-like phenotype of PAH-PASMCs and improving PAH in animal models remains unknown. PASMCs isolated from PAH patients were exposed to different concentrations of TFP before assessments of cell proliferation and apoptosis. The in vivo therapeutic potential of TFP was tested in two preclinical models with established PAH, namely the monocrotaline and sugen/hypoxia-induced rat models. Assessments of hemodynamics by right heart catheterization and histopathology were conducted. TFP showed strong anti-survival and anti-proliferative effects on cultured PAH-PASMCs. Exposure to TFP was associated with downregulation of AKT activity and nuclear translocation of forkhead box protein O3 (FOXO3). In both preclinical models, TFP significantly lowered the right ventricular systolic pressure and total pulmonary resistance and improved cardiac function. Consistently, TFP reduced the medial wall thickness of distal PAs. Overall, our data indicate that TFP could have beneficial effects in PAH and support the view that seeking new uses for old drugs may represent a fruitful approach.

Oral Administration of Clinical Stage Drug Candidate SENS-401 Effectively Reduces Cisplatin-induced Hearing Loss in Rats.

HYPOTHESIS: SENS-401, an oral clinical-stage drug, may reduce cisplatin-induced hearing loss and cochlear damage in an in vivo model. BACKGROUND: Cisplatin is commonly associated with hearing loss, causing significant learning and behavioral difficulties in the pediatric cancer population, and for which there are currently no clinical solutions. SENS-401 has previously been shown to improve acoustic trauma-induced hearing loss in vivo. METHODS: The effect of SENS-401 (R-azasetron besylate) on cisplatin IC50 values was evaluated in a panel of cisplatin-sensitive cell lines (NIH:OVCAR-3, SK-N-AS, NCI-H460, FaDu). Auditory brainstem response and distortion product otoacoustic emission tests were performed in a rat model of cisplatin-induced hearing-loss (8 mg/kg, day 1) at baseline, and after 14 days of SENS-401 (6.6, 13.2, 26.4 mg/kg/d). Cochlear outer hair cells were counted after immunolabeling for myosin-VIIa. RESULTS: Cisplatin cytotoxicity was not impacted by the addition of SENS-401 (up to 10 µM) in any of the cell types evaluated. In vivo, all SENS-401 doses significantly improved auditory brainstem response threshold shift (up to 30 dB) and distortion product otoacoustic emission amplitude loss (up to 19 dB) over placebo. Body weight and survival were not significantly different between rats receiving placebo and those receiving 26.4 mg/kg SENS-401. Significantly more surviving outer hair cells were present after SENS-401 treatment compared with placebo (p < 0.001), with up to 11-fold more in the basal turn of the cochlea. CONCLUSION: In vivo and in vitro data support the otoprotective potential and tolerability of SENS-401 without impacting chemotherapeutic potential. Oral SENS-401 is a promising candidate for treating cisplatin-induced ototoxicity.