Background: Lung cancer is the most lethal form of cancer in the world.Sunitinib is a promising multi-targeted receptor tyrosine kinase (RTK) inhibitor with activity against vascular endothelial growth factor receptors (VEGFR-1 and-2), platelet-derived growth factor receptors (PDGFR-α and-β), stem-cell factor receptor (KIT), etc.However, drug resistance has limited its clinical application.In order to investigate the possibility of reversion of multidrug resistance in lung adenocarcinoma cell line A549, the study attempted to explore the anti-tumor synergistic effect of dopamine on sunitinib in a human non-small lung cancer xenograft, as well as to develop the PK/PD models of this combination therapy.