Small-Molecule CSF1R Inhibitors as Anticancer Agents

: Persuasive evidence has been presented linking the infiltration of tumor-associated macrophages (TAMs) with the driving force of tumorigenesis and in the suppression of antitumor immunity. In this context CSF1R, the cellular receptor for colony stimulating factor-1 (CSF1) and interleukin 34 (IL-34), occupies a central role in manipulating the behavior of TAMs and the dysregulation of CSF1R signaling has been implicated in cancer progression and immu-nosuppression in many specific cancers. Consequently, CSF1R kinase has been a target of great interest in cancer treatment and significant research efforts have focused on development of small-molecule CSF1R inhibitors. In this review, we highlight current progress on the development of these small molecule CSF1R inhibitors as anticancer agents. Special attention is paid to the compounds available in advanced clinical trials.