Differential Mechanisms of the Effect of Peroxisome Proliferator-Activated Receptor Gamma Agonists on Bleomycin-Induced Lung Fibrosis

Background and Objectives: Peroxisome proliferator-activated receptor-g (PPAR-g) is a nuclear receptor whose activation regulates inflammation and fibrosis in various organs. We aimed to investigate the effect of two PPAR-g ligands, telmisartan and rosiglitazone, on lung injury and fibrosis induced by intratracheal bleomycin (BLM). Methods: Lung injury and fibrosis was induced in female C57Bl/6 mice by intratracheal instillation of 1.0 mg/kg of BLM. Some of the animals received rosiglitazone intraperitoneally or telmisartan in drinking water. Bronchoalveolar lavage (BAL) was performed 2, 7, 14 or 21 days after BLM instillation for cell counting and measurement of mediators in the lung. In a separate series, the lungs were sampled for collagen assay and histopathological evaluation. Results: Treatment with rosiglitazone or telmisartan significantly attenuated the BLM-induced increases in lung collagen content, pathological score, and inflammatory cells in BAL fluid. Rosiglitazone significantly suppressed BLM-induced elevation of TGF-b1, MCP-1, and IL-6 levels in the lung. In contrast, telmisartan made no changes in these cytokines, whereas it mitigated the BLM-induced increase in prostaglandin F2a in the lung. Higher concentrations of rosiglitazone and telmisartan attenuated proliferation of lung fibroblasts in vitro. Conclusions: Two PPAR-g ligands, rosiglitazone and telmisartan, exert protective effects on BLM-induced lung fibrosis through the suppression of different profibrotic mediators.

Activity and bioavailability of tepotinib for leptomeningeal metastasis of NSCLC with MET exon 14 skipping mutation

Tepotinib is a key drug for cancer patients with mesenchymal-epithelial transition receptor tyrosine kinase proto-oncogene(MET)exon 14 skipping mutation.However,its bioavailability in the cerebrospinal fluid(CSF)in humans has not been fully elucidated.Moreover,information about the efficacy of tepotinib in patients with leptomeningeal metastasis is limited.Here,we present the case of a 56-year-old man who was diagnosed with lung adenocarcinoma with MET exon 14 skipping mutation.He was urgently hospitalized due to leptomeningeal metastasis.We administered tepotinib 500 mg/day as the second-line therapy and observed improvement in leptomeningeal metastasis and performance status.The tepotinib concentrations reached 1,648 ng/mL in the plasma and 30.6 ng/mL in the CSF,with a penetration rate(CSF/plasma)of 1.83%.These demonstrate tepotinib could achieve a high rate of central nervous system transition and could be effective against leptomeningeal metastasis.