We speculate that cabergoline treatment reduces vascular permeability and inflammation within the SCLC PDX tumour microenvironment, leading to increased expression of D2R on the surface of tumour microenvironment resident endothelial cells, potentially through feedback mechanisms resulting from activation of the Wnt/β-catenin signalling pathway and upregulation of ZO-1. This evidence concerns the gene TJP1 and small cell lung carcinoma.