Early clinical data suggest good tolerability of CSF1/CSF1R-targeting compounds; however, available efficacy data are still limited, with the exception of compelling anti-tumor activity observed in diffuse-type tenosynovial giant cell tumors (dt-GCT), a benign connective tissue disorder driven by CSF1 in an autocrine fashion [12]. The gene discussed is CSF1; the disease is tenosynovial giant cell tumor, diffuse type.