Determination of Camlipixant (BLU-5937) P2X3 antagonist activity in a sensory neuronal model and bronchial epithelial cells

The P2X3 receptor is a promising target for the treatment of chronic cough. Camlipixant (BLU-5937) is a non-competitive P2X3 homotrimeric receptor antagonist and evidence from early clinical trials suggests antitussive activity in patients with refractory and unexplained chronic cough. The objective of this study was to better characterize the mechanism of action of camlipixant in a human in vitro sensory neuronal model and human primary bronchial epithelial cells (PBECs). A model of sensory nerves, termed peripheral neuronal equivalents (PNEs), were differentiated from fibronectin enriched human dental pulp stem cells isolated from dental pulp of extracted third molar teeth. The neuronal profile of PNE cultures was confirmed by immunocytochemistry for the neuronal markers, MAP2, βIII-tubulin and S100. PBECs were obtained from individuals undergoing bronchoscopy and cultured using submerged culture techniques. P2X3 expression in both PNEs and PBECs were investigated by qPCR and immunocytochemistry. Functional P2X3 protein responses in PBECs and PNEs were determined by live-cell calcium imaging using the P2X3 agonist α,βmeATP [400 µM] and antagonist camlipixant [0.1, 0.5 & 2.5 µM]. PNEs express neuronal markers. P2X3 gene and protein expression was observed in both PNEs and PBECs (N=3). PNE calcium mobilisation responses to α,βmeATP were blocked by camlipixant (0.1 µM(P<0.01), 0.5 µM(P<0.01) & 2.5 µM(P<0.001), (N=8–25 cells). PBEC calcium mobilisation responses to 400 µM α,βmeATP were blocked by camlipixant (0.1 µM(P<0.001), 0.5 µM(P<0.01) & 2.5 µM(P<0.001), (N=11–31 cells). Both PNEs and PBECs express functional P2X3 receptors. Camlipixant acted as a potent P2X3 antagonist of receptor excitation in both cell types.