KDR and pemphigus foliaceus: Nintedanib, an FDA-approved drug for the treatment of PF, is a small molecule tyrosine kinase inhibitor (TKI) that binds to a family of growth factor receptors, including platelet-derived growth factor receptors (PDGFR), fibroblast growth factor receptors (FGFR), and vascular endothelial growth factor receptors (VEGFR) [30, 31].