Tryptophan 2,3-dioxygenase (TDO), an immunosuppressive enzyme, can involve in immune evasion and tumor tolerance. TDO inhibitors can boost the efficacy of chemotherapeutics by promoting immunity. Herein, a strategy to introduce a TDO inhibitor into Pt(IV) complexes for reversing tumor immune suppression was adopted. A mono-modified Pt(IV) complex, 3, displayed significant antitumor activity against human liver cancer cells. Flow cytometry study revealed that complex 3 could induce cell death via a mitochondrial-dependent apoptosis pathway and arrest the cell cycle at S phase. Furthermore, complex 3 was effective to enhance T-cell immune responses by inhibiting the TDO enzyme expression to block the kynurenine production and inactivating the downstream of aryl hydrocarbon receptor (AHR).

色氨酸2,3-二加氧酶（TDO）是一种免疫抑制酶，可能参与免疫逃逸和肿瘤耐受性。TDO抑制剂可通过增强免疫力来增强化学疗法的功效。在本文中，采用了将TDO抑制剂引入Pt（IV）复合物中以逆转肿瘤免疫抑制的策略。单修饰的Pt（IV）配合物3对人肝癌细胞显示出显着的抗肿瘤活性。流式细胞仪研究表明复合物3可以通过线粒体依赖性细胞凋亡途径诱导细胞死亡，并使细胞周期停留在S期。此外，复杂3 通过抑制TDO酶表达来阻断犬尿氨酸的产生并使芳烃受体（AHR）的下游失活，从而有效地增强了T细胞的免疫反应。