These systems faithfully recapitulate key components of the tumor-immune microenvironment—such as tumor-associated fibroblasts, dendritic cells, macrophages, and cytotoxic T lymphocytes—and enable direct testing of how interventions targeting TGF-β, IDO1, or CSF1R can reverse immune suppression and restore anti−tumor cytotoxicity. The gene discussed is CSF1R; the disease is neoplasm.