CSF1R-IN-26 (Compound III-1) is an inhibitor of CSF-1R with an IC50 of 20.07 nM. It promotes the polarization of M2 macrophages to M1 macrophages, inducing apoptosis in MC-38 cancer cells. CSF1R-IN-26 inhibits the activation of the AKT/ERK/STAT3 signaling pathways, remodels the tumor immune microenvironment, and exhibits antitumor activity in mouse models. In SD rats, CSF1R-IN-26 demonstrates favorable pharmacokinetic properties, with a half-life of 1.86 hours and an oral bioavailability of 79.22%.