A humanized immunoglobulin (Ig) G4 monoclonal antibody directed against colony-stimulating factor 1 receptor (CSF-1R), with potential antineoplastic activity. Upon intravenous administration, axatilimab binds to the ligand binding domain of CSF-1R, preventing binding and consequent activation by its natural ligands, IL-34 and colony-stimulating factor 1 (CSF-1). Inhibition of CSF-1R activation may disrupt the activity of tumor-associated macrophages (TAMs), which promote initiation and metastasis of tumor cells, inhibit T-cell responses, and stimulate tumor angiogenesis and disease progression. CSF-1R, also known as macrophage colony-stimulating factor receptor (M-CSFR) and cluster of differentiation 115 (CD115), is a tyrosine-protein kinase that plays an essential role in the regulation, proliferation, survival and differentiation of tissue macrophages as well as TAMs.