IDO1 and Immunotolerance in Glioblastoma

项目摘要 该R 01更新提案旨在扩展PI过去的生产力，包括自 2016年，包括3篇临床癌症研究中的高级作者手稿和2篇其他作品 正在《神经肿瘤学》和《自然》杂志上进行评论。PI更新申请的科学前提是 连续NIH/NINDS F32（博士后NRSA），NIH/NINDS K99/R 00（Pathway To Independence）和NIH/NINDS R 01支持，共同关注吲哚胺的研究 2，3双加氧酶1（IDO; IDO 1）在胶质母细胞瘤（GBM）中的作用。IDO在>90%的所有患者切除的GBM中表达 并有效抑制抗GBM免疫应答。IDO表达通过GBM浸润T细胞增加， 细胞，因此代表了对基于免疫的疗法的抗性的关键机制，因为靶向 旨在增强T细胞浸润到GBM中的方法将反过来导致IDO的代偿性增加。 抗GBM免疫应答的表达和抑制。重要的是，高肿瘤内IDO 表达与GBM患者存活率显著降低和免疫抑制性增加相关。 调节性T细胞（CD 4 + CD 25 + FoxP 3+）。由于IDO被规范地表征为限速酶， 将必需氨基酸色氨酸（Trp）代谢成下游代谢物犬尿氨酸（Kyn）， Trp的耗尽和/或Kyn的积累是IDO如何抑制细胞凋亡的假定机制。 抗GBM免疫反应。然而，我们的工作挑战了这一假设，部分支持通过 用（i）空表达载体，（ii）载体， 表达野生型IDO，（iii）或表达酶失活IDO的载体。当颅内植入 同基因小鼠脑GBM细胞IDO表达增加TcR并降低存活率， 色氨酸代谢我们的集体结果表明，GBM细胞IDO代表了一种复杂的机制， 免疫抗性促使我们开发IDO-蛋白水解靶向嵌合体（IDO-PROTAC） - 在一些实施方案中，本发明涉及与IDO蛋白结合并募集E3泛素连接酶以促进蛋白酶体降解的化合物。 IDO-PROTAC使实验能够解决不依赖于酶的IDO免疫抑制作用。 因此，我们的建议的目的是（i）调查负责GBM细胞IDO酶的机制， 独立免疫抑制和（ii）设计、产生和优化介导IDO的新型IDO-PROTAC 人GBM细胞中的蛋白质降解。确定IDO如何抑制免疫应答组合 随着有效IDO-PROTAC的产生，将解决有关GBM免疫生物学的知识空白，同时还 改善用免疫疗法和IDO-PROTAC共同治疗的GBM患者的治疗结果。

PROJECT SUMMARY This R01 renewal proposal intends to extend the PI's past productivity that includes 35 publications since the year, 2016, including 3 senior-authored manuscripts in Clinical Cancer Research and 2 additional bodies of work that are under review in Neuro-Oncology and Nature. The scientific premise of the PI's renewal application is an extension of continuous NIH/NINDS F32 (Postdoctoral NRSA), NIH/NINDS K99/R00 (Pathway To Independence) and NIH/NINDS R01 support that have collectively focused on the investigation of indoleamine 2,3 dioxygenase 1 (IDO; IDO1) in glioblastoma (GBM). IDO is expressed in >90% of all patient-resected GBM and potently suppresses the anti-GBM immune response. IDO expression is increased by GBM-infiltrating T cells and therefore represents a key mechanism of resistance to immune-based therapies, since targeted approaches that aim to enhance T cell infiltration into GBM, will in-turn, result in a compensatory increase of IDO expression and suppression of the anti-GBM immune response. Importantly, the high intratumoral IDO expression is associated with significantly decreased GBM patient survival and increased immunosuppressive regulatory T cells (CD4+CD25+FoxP3+). Since IDO is canonically characterized as a rate-limiting enzyme that metabolizes the essential amino acid, tryptophan (Trp), into the downstream metabolite, kynurenine (Kyn), the depletion of Trp and/or accumulation of Kyn has been the presumed mechanism of how IDO suppresses the anti-GBM immune response. However, our work has challenged this hypothesis, supported in-part through the creation of IDO-deficient murine GBM cells reconstituted with either (i) empty expression vector, (ii) a vector expressing wild-type IDO, (iii) or a vector expressing enzyme-inactive IDO. When intracranially-engrafted into the syngeneic mouse brain, GBM cell IDO expression increases Tregs and decreases survival independent of tryptophan metabolism. Our collective results indicate that GBM cell IDO represents a complex mechanism of immune resistance that has motivated our development of IDO-proteolysis targeting chimeras (IDO-PROTACs) - compounds that bind to IDO protein and recruit an E3 ubiquitin ligase to facilitate proteasome degradation. IDO-PROTACs enable experiments to address IDO immunosuppressive effects that are enzyme independent. The aims of our proposal are therefore to (i) investigate the mechanism responsible for GBM cell IDO enzyme independent immunosuppression and (ii) design, create and optimize novel IDO-PROTACs that mediate IDO protein degradation in human GBM cells. Determination of how IDO suppresses the immune response combined with the generation of potent IDO-PROTACs will address knowledge gaps about GBM immunobiology while also improving treatment outcomes of GBM patients that are co-treated with immunotherapy and IDO-PROTACs.