To address this question, we established a simple, well-defined 3D macrophage-tumor spheroid (MTS) co-culture model consisting of human monocyte-derived macrophages (MDMs) and the human ER+ PR+ HER2+ breast cancer line BT-474 and used it to characterize the effects of CSF1R inhibition and CD40 activation. The gene discussed is CSF1R; the disease is breast carcinoma.