Optimizing Therapeutic STING Agonism in Triple Negative Breast Cancer

项目总结 尽管STING激动剂在癌症中有治疗希望，但首先在人类研究中受到阻碍 缺乏精确的治疗和药物输送方面的问题。我的实验室研究三重阴性乳腺癌 (TNBC)是一种高度侵袭性的乳腺癌，治疗选择有限，预后差。最近， 我们在TNBCs的一个主要亚群中揭示了过度活跃的天然免疫信号的机制基础。 具体地说，我们发现PTEN的丢失与TBK1/IKKepsilon激酶共同失活Rab7，这限制了 刺痛的溶酶体降解。这使得PTEN缺失的TNBCs对刺痛激动剂特别敏感。我们的 长期目标是利用这一知识为TNBC开发有效的基于刺激剂的免疫疗法。 总体目标是以我们的初步发现为基础，更全面地提高刺激剂的疗效。 在TNBCs中，通过防止STING降解和改善STING激动剂的输送。我们的中心假设是 延长肿瘤细胞的刺激性将更有效地抑制TNBC的生长并增强抗肿瘤作用 豁免权。这个项目的基本原理是，在肿瘤微环境中保留刺痛激动感的能力 将有助于在临床环境下提高其治疗效果。中心假设将是 通过追求三个特定目标进行测试：1)通过抑制Rab7增加刺细胞留存；2)靶自适应 TREX1上调促进cGAS-STING上游激活；3)体内检测和比较 STING激动剂瘤内注射与对照的药代动力学和抗肿瘤效应 在聚乙二醇化的乳腺活检标记物中受孕。鉴于我们的发现，PTEN缺失的TNBCs可以防止 通过保持Rab7处于非活动状态来降解刺，我们将首先研究Rab7是否 抑制剂CID1067700和Rab7基因敲除可扩大对PTEN WT TNBCs的刺激性。在第二个下面 目的：我们将测试通过抑制TREX1而增加胞浆dsDNA水平是否会进一步过度激活。 CGAS-STING函数。在第三个目标中，使用4T1 TNBC小鼠模型，我们计划嵌入刺激剂 将含有聚乙二醇聚合物的现有乳腺活检标记物立即用于临床 与瘤内注射相比，在肿瘤微环境中维持刺激性的可行方法。这个 申请人认为，本申请中提出的研究是创新的，因为它代表了一项实质性的 通过解决刺痛降解和激动剂持续时间这一根本问题来改变现状 通过多方面的方法进行曝光。这项拟议的研究意义重大，因为它预计将有一个 重要的积极影响，通过提供强有力的循证方法在临床上保留刺痛的激动感 试验环境，以使结果的治疗结果是可解释的，并且不将负面结果归因于 要药物渗漏还是要细胞固有降解的刺痛。归根结底，这样的知识有可能 为有未得到满足的需求的TNBC患者揭示新的治疗策略。

PROJECT SUMMARY Despite the therapeutic promise of STING agonists in cancer, first in human studies have been hampered by lack of precision therapy and issues with drug delivery. My laboratory studies triple negative breast cancer (TNBC), a highly aggressive breast malignancy with limited therapeutic options and a poor prognosis. Recently, we uncovered the mechanistic basis for hyperactive innate immune signaling in a major subset of TNBCs. Specifically, we found that PTEN loss conspires with the kinases TBK1/IKKepsilon to inactivate Rab7, which limits lysosomal degradation of STING. This renders PTEN null TNBCs particularly sensitive to STING agonists. Our long-term goal is to utilize this knowledge to develop effective STING agonist-based immunotherapy for TNBC. The overall objectives are to build upon our initial findings and enhance STING agonist efficacy more generally in TNBCs by preventing STING degradation and improving STING agonist delivery. Our central hypothesis is that prolonged STING agonism in tumor cells will more effectively abrogate TNBC growth and boost anti-tumor immunity. The rationale for this project is that the ability to retain STING agonism in the tumor microenvironment will be instrumental to enhancing its therapeutic efficacy in the clinical setting. The central hypothesis will be tested by pursuing three specific aims: 1) Increase STING cellular retention by inhibiting Rab7; 2) Target adaptive TREX1 upregulation to boost cGAS-STING activation upstream; and 3) Examine and compare in vivo pharmacokinetics and anti-tumor efficacy of STING agonist when delivered via intra-tumoral injection versus impregnation in a PEGylated breast biopsy marker. Given our findings that PTEN null TNBCs prevent degradation of STING by maintaining Rab7 in an inactive state, we will study in the first aim whether the Rab7 inhibitor CID1067700 and Rab7 knockout can broaden STING agonism to PTEN WT TNBCs. Under the second aim, we will test whether increasing levels of cytosolic dsDNA through TREX1 inhibition will further hyperactivate cGAS-STING function. In the third aim, using the 4T1 TNBC mouse model, we plan to embed STING agonists into pre-existing breast biopsy markers containing polyethylene glycol polymers as an immediate clinically actionable way to maintain STING agonism in the tumor microenvironment versus intratumoral injection. The research proposed in this application is innovative, in the applicant's opinion, because it represents a substantive departure from the status quo by tackling this essential problem of STING degradation and duration of agonist exposure via a multifaceted approach. The proposed research is significant because it is expected to have an important positive impact by providing a strong evidence-based method to retain STING agonism in the clinical trial setting, such that resultant therapeutic findings are interpretable and negative outcomes are not attributed to drug leakage or to cell intrinsic degradation of STING. Ultimately, such knowledge has the potential of uncovering a new therapeutic strategy for patients with TNBC where there is an unmet need.