Colony stimulating factor-1 (CSF1) is a cytokine that is involved in the recruitment and activation of tissue macrophages. It exerts these effects by binding to its corresponding receptor tyrosine kinase, the cFMS/CSF1 receptor (CSF1R). Pexidartinib is a brain-penetrant inhibitor of CSF1R, as well as c-Kit and FLT3 (IC50s = 20, 10, and 160 nM in vitro, respectively). It has been used in combination with paclitaxel to block macrophage recruitment in mammary tumor-bearing mice, thus slowing primary tumor development and metastasis. Pexidartinib has also been used to block microglial stimulation of glioblastoma invasion in both cell culture and a mouse model of glioblastoma multiforme.
