CSF1R and osteosarcoma: Interestingly, Fujiwara et al. reported that PLX3397 (pexidartinib) as a potent inhibitor of CSF1R approved by the Food and Drug Administration (FDA) reduced pERK1/2 and M2 polarization induced by CSF1R and also tumor growth and lung metastasis in vivo by depletion of TAMs and FOXP3+ Tregs and enhancement of infiltration of CD8+ T cells into primary and metastatic osteosarcoma [43, 221].