Preclinical assessment of efficacy and tumor microenvironment alterations by PPRX-1701 in glioblastoma

项目总结/摘要 恶性脑肿瘤胶质母细胞瘤（GBM）仍然无法治愈，患者结局几乎没有改善 几十年来。免疫治疗的成功，如免疫检查点阻断（ICB）在其他疾病中的应用 迄今为止，在GBM中还没有复制癌症。GBM免疫疗法的有效应用可能需要 基于对分子生物学和免疫抑制的详细了解的联合疗法 肿瘤微环境（TME）中的机制，以及合理的协同作用的临床前研究 治疗组合，为未来的临床试验提供信息和开发有效的临床试验。在重新提交的R21提案中， 我们将建立在显示药物抑制IDO 1表达和改变GBM中TME的初步数据上， PPRX-1701是一种新开发的靛玉红衍生物6-溴靛玉红-3 '- 丙酮肟（BiA），以了解其作用机制，并提供可能支持其使用的临床前数据 在人类GBM患者中。BiA是靛玉红的化学修饰形式，靛玉红是从靛蓝中提取的天然产物。 一种植物，是抗炎中药的活性成分，已被用于 治疗慢性粒细胞白血病和牛皮癣。我们先前发表的研究表明，BiA可以 通过对侵袭、增殖和血管生成的影响延长人GBM异种移植物在小鼠中的存活。 然而，我们没有研究BiA的潜在免疫学作用，以及这种作用的进一步发展。 概念受到溶解度差的阻碍，这限制了在患者中的适用性。 PPRX-1701是一种BiA/共聚物纳米颗粒混悬液，可通过以下方式安全有效地全身递送： 静脉内注射，其中它增加携带GBM的免疫活性小鼠的存活率。我们最初的研究 PPRX-1701在鼠GBM中显示出颅内肿瘤的靶向作用和TME组成的改变，包括 增加的CD 8 + T细胞和减少的肿瘤促进巨噬细胞。我们还表明，BiA/PPRX- 1701有效地阻断了干扰素-γ-干扰素对免疫抑制酶IDO 1的诱导，因此， 假设BiA/PPRX-1701促进TME的改变是由于免疫抑制剂的抑制， 途径，提高动物生存率和抗肿瘤免疫力。在这里，我们在目标1中提出， 在多种鼠GBM模型中的给药、生物分布、毒性和功效。在目标2中，我们将描述 详细描述了与体内PPRX-1701治疗相关的分子和细胞变化，以及试验组合 如果数据支持的话，我们将研究免疫疗法，以期进行临床转化。 本文描述的实验将快速建立PPRX-1701用于GBM的机制和适用性 治疗，并为未来的详细研究和知情的临床试验提供平台。

Project Summary/Abstract The malignant brain tumor glioblastoma (GBM) remains incurable with little improvement in patient outcomes over many decades. The success of immunotherapies such as immune checkpoint blockade (ICB) in other cancers has not been replicated so far in GBM. Effective application of immunotherapy for GBM may need combination therapies based on detailed understanding of molecular biology and immunosuppressive mechanisms in the tumor microenvironment (TME), as well as preclinical studies of rational synergistic therapeutic combinations to inform and develop effective future clinical trials. In this resubmitted R21 proposal we will build on preliminary data showing inhibition of expression of IDO1 and altered TME in GBM by the drug PPRX-1701, a newly developed bioavailable formulation of the indirubin derivative 6-bromoindirubin-3'- acetoxime (BiA), to understand its mechanism of action and provide preclinical data which may support its use in human GBM patients. BiA is a chemically modified form of indirubin, a natural product derived from the indigo plant which is an active component of anti-inflammatory Traditional Chinese Medicines, which has been used to treat chronic myelogenous leukemia and psoriasis. Our previously published studies showed that BiA could prolong survival of human GBM xenografts in mice via effects on invasion, proliferation and angiogenesis. However, we did not examine the potential immunological effects of BiA, and the further development of this concept was hampered by poor solubility which limits applicability in patients. PPRX-1701 is a BiA/copolymer nanoparticle suspension that can be efficiently systemically delivered safely by intravenous injection, where it increases survival in GBM-bearing immunocompetent mice. Our initial studies of PPRX-1701 in murine GBM show targeting of intracranial tumors and alterations in TME composition including increased CD8+ T cells, and decreased tumor promoting macrophages. We have also shown that BiA/PPRX- 1701 potently blocks induction of the immunosuppressive enzyme IDO1 by interferon- We therefore hypothesize that BiA/PPRX-1701 promotes alterations in the TME as a result of inhibition of immunosuppressive pathways, increasing animal survival and anti-tumor immunity. Here we propose in Aim 1 to determine optimal dosing, biodistribution, toxicity and efficacy in multiple murine GBM models. In Aim 2 we will characterize in detail the molecular and cellular alterations associated with PPRX-1701 treatment in vivo, and test combination immunotherapies with a view to clinical translation if data supports. The experiments described here will rapidly establish mechanism and applicability of PPRX-1701 for GBM treatment, and provide a platform for future detailed studies and informed clinical trials.