A novel therapeutic strategy to eradicate breast cancer through Hsp90 inhibition and reduced immune tolerance

摘要： 免疫疗法正在成为癌症治疗的支柱，许多有反应的患者经历了 持久的甚至是治愈性的结果。然而，由于尚不清楚的原因，只有少数癌症 患者受益于免疫检查点阻断（ICB）疗法。扩展这个非凡的 目前正在通过多种途径积极寻求对大多数癌症患者的治疗，包括 联合免疫疗法，如阻断PD-1和CTLA-4。此外，令人鼓舞的结果 当ICB疗法与现有的化疗联合使用时， 免疫介导的抗肿瘤应答。这为使用小分子提供了可能性， 恢复免疫系统对癌细胞作为外来实体的识别， 免疫进展。在这种情况下，我们已经确定了一个环肽，EnnA，作为一种新的抑制剂， 热休克蛋白90（Hsp 90），具有释放免疫系统对抗肿瘤细胞的强大能力。 这一发现源于我们努力寻找新的Hsp 90抑制剂，以规避已知的副作用 阻碍了第一代抑制剂的临床进展。特别是，这种化合物 不诱导热休克反应，这降低了早期抑制剂的疗效，通过激活 促生存机制。EnnA诱导免疫原性癌细胞死亡，促进肿瘤免疫细胞 渗透，并释放强大的T细胞介导的免疫反应，导致高度有效的 在同基因小鼠模型中的肿瘤杀伤。在分子水平上，EnnA干扰几种致癌途径 并降低程序性细胞死亡配体-1（PD-L1）的蛋白水平，PD-L1是肿瘤的关键介质， 诱导免疫耐受。因此，我们认为EnnA是一种很有前途的靶向抗肿瘤药物。 热休克蛋白90通过一种新的作用机制，涉及癌细胞毒性，增加其免疫原性 以及调节肿瘤微环境以降低免疫耐受性。在目标1中，我们将 EnnA作为药物的临床前开发，以确定其毒性和EnnA对 小鼠的免疫系统。我们还将通过突变和突变来表征EnnA-Hsp 90相互作用。 生化分析在目标2中，我们将确定EnnA如何抑制Hsp 90干扰PD-L1 陪伴和功能。在目标3中，我们将定义EnnA抗肿瘤的免疫细胞机制。 效果将测试EnnA与抗CTLA-4的组合，并对免疫细胞进行全面分析。 参与抗肿瘤活动将得到实施。在目标4中，我们将测试EnnA的重要性- 诱导的癌细胞自噬和Hsp 90在免疫依赖性肿瘤根除中的细胞表面暴露。 如果成功，这些研究将阐明Hsp 90在促进免疫耐受中的作用， 提供了使用新的Hsp 90抑制剂增强免疫治疗的创新方法。

Abstract: Immunotherapy is becoming a pillar of cancer treatment, and many responsive patients have experienced durable, or even curative, outcomes. For reasons that remain unclear, however, only a minority of cancer patients benefit from immune checkpoint blockade (ICB) therapies. Expanding this remarkable achievement to most cancer patients is being actively sought through multiple avenues, including combined immunotherapy, such as blocking both PD-1 and CTLA-4. In addition, promising results have been observed when ICB therapies were combined with available chemotherapies that potentiate the immune-mediated anti-tumor response. This opens the possibility that the use of small molecules could restore the immune system’s recognition of cancer cells as a foreign entity and thus would potentiate immunotherapeutic progress. In this context, we have identified a cyclic peptide, EnnA, as a novel inhibitor of heat shock protein 90 (Hsp90), with a potent ability to unleash the immune system against tumor cells. This discovery stemmed from our effort to find new Hsp90 inhibitors that circumvent known side effects that have hampered the clinical progress of first-generation inhibitors. In particular, this compound does not induce a heat shock response, which had reduced the efficacy of early inhibitors through activation of pro-survival mechanisms. EnnA induces immunogenic cancer cell death, promotes tumor immune cell infiltration, and unleashes a powerful T cell-mediated immune response, resulting in highly efficacious tumor killing in a syngeneic mouse model. Molecularly, EnnA interferes with several oncogenic pathways and reduces the protein level of the programmed cell death ligand-1 (PD-L1), a key mediator of tumor- induced immune tolerance. We therefore propose that EnnA is a promising anti-tumor agent targeting Hsp90 through a novel mechanism of action involving cancer cell toxicity that increases its immunogenicity and modulation of the tumor microenvironment to reduce immunotolerance. In Aim 1, we will perform preclinical development of EnnA as a drug to determine its toxicity and the potential impact of EnnA on the immune system of mice. We will also characterize the EnnA-Hsp90 interaction through mutational and biochemical analyses. In Aim 2, we will determine how inhibition of Hsp90 by EnnA interferes with PD-L1 chaperoning and function. In Aim 3, we will define immune cell mechanisms underlying EnnA’s anti-tumor effect. Combining EnnA with anti-CTLA-4 will be tested, and comprehensive profiling of immune cells involved in the anti-tumor activity will be implemented. In Aim 4, we will test the importance of EnnA- induced cancer cell autophagy and Hsp90 cell surface exposure in immune-dependent tumor eradication. If successful, these studies will shed light on the role of the Hsp90 in promoting immune tolerance and will provide an innovative approach to potentiate immunotherapy using a novel Hsp90 inhibitor.