KDR and neoplasm: Similar to nintedanib, regorafenib (RG) is an oral multi-kinase inhibitor that can effectively block multiple protein kinases of tumor angiogenesis, tumorigenesis, tumor metastasis, and tumor immunity, such as VEGFR (vascular endothelial growth factor receptor), TIE2 (endothelial tyrosine kinase Tie2), c-KIT (c-kit proto-oncogene), RET (RET proto-oncogene) and CSF1R (Colony-stimulating factor 1 receptor) [20,21].