These findings conclusively demonstrated that pharmacological inhibition of CSF-1R activity by ABSK021 resulted in significant anti-tumor effects in preclinical osteosarcoma models with CSF-1R overexpression. The high prevalence of CSF-1R expression observed in osteosarcoma patient samples highlights the potential clinical use of ABSK021, either as a monotherapy or in combination with chemotherapy, as a promising therapeutic strategy for osteosarcoma patients with CSF-1R as a potential predictive biomarker.