T细胞免疫疗法在治疗实体肿瘤方面具有潜力，但其治疗效果受到肿瘤内免疫抑制的限制。这种免疫抑制性肿瘤微环境主要由肿瘤相关的骨髓细胞介导，包括巨噬细胞。在这里，我们报道了一种名为桃金娘素（TSN）的小分子化合物，通过转录巨噬细胞来增强小鼠模型中胶质母细胞瘤（GBM）的抗肿瘤免疫力。我们使用化学文库筛选了基因探针的功能性巨噬细胞，并发现TSN能够逆转巨噬细胞介导的肿瘤免疫抑制，导致T细胞浸润、激活和减轻疲劳。化学蛋白组学和结构分析表明，TSN与Hck和Lyn相互作用，以消除抑制性巨噬细胞免疫力。此外，免疫检查点阻滞和TSN治疗的组合使小鼠中的同基因GBM肿瘤发生回归。此外，TSN治疗增强了GBM对Egfrviii嵌合抗原受体（CAR）T细胞疗法的敏感性。这些发现表明TSN可能作为一种治疗化合物，阻断肿瘤免疫抑制，规避肿瘤对T细胞免疫疗法的耐药性，并值得进一步研究。

T cell-based immunotherapy holds promise for treating solid tumors, but its therapeutic efficacy is limited by intratumoral immune suppression. This immune suppressive tumor microenvironment is largely driven by tumor-associated myeloid cells, including macrophages. Here, we report that toosendanin (TSN), a small-molecule compound, reprograms macrophages to enforce antitumor immunity in glioblastoma (GBM) in mouse models. Our functional screen of genetically probed macrophages with a chemical library identifies that TSN reverses macrophage-mediated tumor immunosuppression, leading to enhanced T cell infiltration, activation, and reduced exhaustion. Chemoproteomic and structural analyses revealed that TSN interacts with Hck and Lyn to abrogate suppressive macrophage immunity. In addition, a combination of immune checkpoint blockade and TSN therapy induced regression of syngeneic GBM tumors in mice. Furthermore, TSN treatment sensitized GBM to Egfrviii chimeric antigen receptor (CAR) T cell therapy. These findings suggest that TSN may serve as a therapeutic compound that blocks tumor immunosuppression and circumvents tumor resistance to T cell-based immunotherapy in GBM and other solid tumors that warrants further investigation.