PLX5622

PLX5622 is a highly selective, brain-penetrant, and orally active small molecule inhibitor of the colony stimulating factor 1 receptor (CSF1R), also known as FMS. It is used primarily in research to deplete microglia and study their role in central nervous system (CNS) biology and disease. By inhibiting CSF1R kinase activity with high potency (IC50 = 0.016 μM), PLX5622 leads to the elimination of microglia and certain other myeloid cell populations in the CNS. Its effects extend beyond microglial depletion, impacting monocyte production and recruitment during neuroinflammation. The drug has demonstrated protective effects in animal models of CNS viral infection by reducing inflammatory monocyte infiltration into the brain[1][3][4][6][7][8]. PLX5622 was initially developed by Daiichi Sankyo.