IDO1/TDO双靶点小分子抑制剂的设计、合成及成药性研究

Cancer immunotherapy targeting immune checkpoint is considered as an exciting approach for cancer treatment. Recent studies demonstrated that indoleamine 2,3-dioxygenase 1 (IDO1) and trytophan 2,3-dioxygenase (TDO) were the novel type of immune checkpoints. IDO1 and TDO have emerged as attractive targets in cancer immunotherapy, which were favored by more and more pharmaceutical companies and research institutions, showing a trend of vigorous development in recent years. Currently, several inhibitors have been reported for IDO1 or TDO, but there is only one dual inhibitor has been reported in the literature with poor activity.Recent studies showed that the inhibitors that target both IDO1 and TDO have greater advantages than only IDO1 or TDO inhibitors, respectively. This study will start from four hit compounds, namely P01-P04, discovered in our previous research work. We shall first adopt structure-based drug design methods to design new dual IDO1/TDO inhibitors, which will be synthesized by chemical means. Then, in-depth studies including structure optimization and structure-activity relationship (SAR) analysis will be carried out on the synthesized compounds. Next, we shall evaluate the preliminary druggability of these compounds, and explore their antitumor response in the LL2 and Hepa1-6 xenograft mouse model. Through the studies, we hope to obtain a number of new dual IDO1 and TDO inhibitors with independent intellectual property rights, highly potent , selectivity and good druggability. It is expected that this study will be lay a solid foundation for the subsequent novel cancer immunotherapy drug development of targeting both IDO1 and TDO.

针对免疫检查点的免疫疗法被认为是未来肿瘤治疗的方向。IDO1和TDO是近年来发现的新型免疫检查点，引起了世界各大制药公司和研究机构的高度关注。目前已有多个分别针对IDO1 和TDO 的小分子抑制剂报道，而同时针对IDO1和TDO的双靶点抑制剂直到最近才有报道，但其活性较差。最近研究表明，相比于IDO1 或TDO 的单靶点抑制剂，双靶标抑制剂具有更大的优势。本研究以前期发现的4个具有IDO1/TDO双重抑制活性的苗头化合物（P01-P04）为基础，综合运用药物分子设计、化学合成、生物活性测试等方法，开展结构优化和构效关系研究。评价小分子的初步成药性，并探索其在LL2及Hepa1-6小鼠模型中的抗肿瘤效果。以期最终获得具有自主知识产权的新颖高活性、选择性，并具有良好成药性的IDO1/TDO的双靶点的小分子抑制剂，为后续展开靶向IDO1/TDO的新型肿瘤免疫治疗药物研发打下坚实基础。

针对免疫检查点的免疫疗法被认为是未来肿瘤治疗的方向。IDO1和TDO作为新型免疫检查点，引起了世界各大制药公司和研究机构的高度关注。单一靶向IDO1和TDO的小分子抑制剂已有大量文献报道，而同时靶向IDO1和TDO的小分子抑制剂直到最近才有所报道，但其活性、成药性均较差。研究表明，相比单一靶向IDO1和TDO的小分子抑制剂，双靶点抑制剂具有更大的优势。在本研究中，我们虚拟筛选商业化合物库（包括Specs、Chembridge、Enamine等），发现了4个活性化合物（P01-P02）。然后我们对活性最高的化合物进行进一步的结构优化，共合成了39个衍生物，通过生物活性测试和构效关系研究，最后发现了化合物38的活性和选择性较好，并排除其为PAINS的可能性。该化合物对IDO1和TDO的IC50分别为5 nM和4 nM，在HeLa（IDO1高表达）和A172（TDO高表达）细胞中呈现出潜在的IDO1和TDO抑制活性。Western Blot分析表明38可有效抑制HeLa细胞中IDO1和A172细胞中TDO的犬尿氨酸代谢途径。38在LL2 和 Hepa1-6 两种异种移植小鼠模型呈现出潜在的抗肿瘤效果，并在 IDO1和TDO 同时高表达的 Hepa1-6 肿瘤模型中呈现出比单靶点抑制剂 INCB024360 更好的抗肿瘤效果。证实，IDO1/TDO 双靶点的抑制剂与其单靶点抑制剂相比具有一定的优势。总之，我们通过虚拟筛选和结构优化，获得了一个具有较高活性和选择性的IDO1/TDO 双靶点的抑制剂，为针对IDO1/TDO 双靶点的抑制剂的小分子靶向药物研发提供了一个良好的先导化合物。