Recent advances in colony stimulating factor-1 receptor (CSF1R) inhibitors

The colony-stimulating factor-1 receptor (CSF1R), also known as CD115 and M-CSF-R, belongs to the family of type III receptor tyrosine kinases (RTKs). Its natural ligands include Colony Stimulating Factor-1 (CSF-1) and Interleukin-34 (IL-34). CSF1R-mediated signaling regulates the survival, proliferation, and differentiation of mononuclear phagocytic cell populations throughout the body, including microglia, and it triggers the complex signaling networks downstream from RTKsleading to the activation and inhibition of multiple gene. CSF1R is aberrantly expressed in multiple tumors and neurodegenerative diseases. Blocking CSF1R signaling to alleviate immunosuppression within the tumor microenvironment and modulate microglial activity represents a promising strategy for enhancing anti-tumor immune responses, as well as specifically targeting CSF1R-associated neurodegenerative disorders and neuroinflammatory conditions. This review summarizes recent advances in CSF1R inhibitor in clinical applications, disease models, and novel targeted delivery systems, focusing on therapeutic progress in oncology and neurological disorders. The article also discusses the binding modes of the inhibitors to the CSF1R, as well as available methods to increase the selectivity and CNS penetration and to reduce potential systemic toxicity.