Bottlebrush polymer prodrugs for targeted delivery of combination therapies and in vivo imaging of pharmacological response

摘要： 胰腺导管腺癌(PDA)是一种致命性疾病，治疗效果不佳。药效不佳 目前的治疗方法包括免疫检查点抑制剂(ICIS)，部分归因于这种特征 纤维炎性促结缔组织增生性肿瘤微环境。因此，克服这些基质障碍的战略 有可能深刻改善PDA的治疗结果。为此，表观遗传疗法 这广泛地改变了细胞基因表达程序，代表了一种有希望的靶向PDA基质的方法 障碍。溴结构域和末端外域(BET)蛋白抑制剂的初步研究 识别增强子和超级增强子驱动细胞特异性功能，揭示了一种潜在的丧失 多种基质细胞群和肿瘤细胞内的免疫抑制程序。此外， 临床BET抑制剂OTX-015OTX与无效的αPD-L1免疫检查点抑制协同作用 促进瘤内细胞毒性T细胞活化，减轻PDA肿瘤负担。然而，OTX的负面影响 影响次级淋巴组织中T细胞的启动，长期治疗受到全身毒性的限制。至 克服这些限制，这项提议将开发瓶刷聚合物前药(BPDs)，以选择性地提供 药物运往PDA肿瘤。BPD是一种小的圆柱形大分子，其中含有多个结合药物 他们的核心。这种独特的结构可提高组织渗透率并独立于可预测的特性 分子连接物有助于药物在靶组织中的高度选择性释放。在目标1中， 含有可切割连接物的OTX-BPD结合物选择性地将药物输送到肿瘤的能力将是 在临床相关的PDA小鼠模型中进行评估。随后，铅OTX-BPD的协同作用能力 对于α，PD-L1将在短期干预和长期生存研究中确定。治疗性 目标2将确定多种药物与BPD结合的效用。具体地说，发现了化疗药物 以游离药物的形式与OTX协同作用，将OTX-BPDs偶联到OTX-BPDs上，这些多药载药的能力 将确定与αPD-L1联合用于抑制肿瘤生长和增强抗肿瘤免疫的BPD 在PDA小鼠模型中。同时，通过以下方式积极靶向这些携带多种药物的BPD的治疗益处 将评估与识别PDA癌细胞蛋白的抗体的结合情况。此外，最优比例 将建立与单个BPD结合以实现最大疗效的药物，这将是独特的 免费的药物。结合起来，靶向多药载药的BPD的开发将促进理性 利用表观遗传疗法和化学疗法来增强免疫检查点的联合疗法 抑制剂。在第三个目标中，将开发用于药物诱导的细胞凋亡和细胞毒T细胞活性的BPD记者 通过加入不含金属的磁共振有机自由基造影剂。这些报告器BPD将用于验证 在目标1和目标2中发展的联合疗法的作用方法。重要的是，这种能力 快速报告治疗效果的BPD有可能为随后的治疗决定提供信息。

ABSTRACT: Pancreatic ductal adenocarcinoma (PDA) is a lethal disease with few effective treatments. The poor efficacy of current therapies including immune checkpoint inhibitors (ICIs) is partly attributed to the characteristic fibroinflammatory desmoplastic tumor microenvironment. Thus, strategies that overcome these stromal barriers have the potential to profoundly improve therapeutic outcomes in PDA. Towards this end, epigenetic therapies that broadly rewire cellular gene expression programs represent a promising approach for targeting PDA stromal barriers. Preliminary studies with inhibitors of Bromodomain and Extra-Terminal domain (BET) proteins, whose recognition of enhancer and super-enhancers drive cell-specific function, reveal a potent loss of immunosuppressive programs within multiple stromal cell populations as well as tumor cells. In addition, the clinical BET inhibitor OTX-015 (OTX) synergized with otherwise ineffective αPD-L1 immune checkpoint inhibition to promote intra-tumoral cytotoxic T cell activation and decrease PDA tumor burden. However, OTX negatively impacts T cell priming in secondary lymphoid tissue and long-term treatment is limited by systemic toxicities. To overcome these limitations, this proposal will develop bottlebrush polymer prodrug (BPDs) to selectively deliver drug cargoes to PDA tumors. BPDs are small, cylindrical macromolecules with multiple conjugated drugs within their cores. This unique architecture enables improved tissue penetration and predictable properties independent of drug composition, while molecular linkers facilitate highly selective drug release in target tissues. In Aim 1, the ability of OTX-BPD conjugates incorporating cleavable linkers to selectively deliver drugs to tumors will be evaluated in clinically relevant PDA mouse models. Subsequently, the ability of lead OTX-BPDs to synergize with αPD-L1 will be determined in both short-term intervention and long-term survival studies. The therapeutic utility of conjugating multiple drugs to BPDs will be determined in Aim 2. Specifically, chemotherapeutics found to synergize with OTX as free drugs will be conjugated to OTX-BPDs, and the abilities of these multidrug laden BPDs to reduce tumor growth and enhance anti-tumor immunity in combination with αPD-L1 will be determined in PDA mouse models. In parallel, the therapeutic benefits of actively targeting these multidrug-laden BPDs by conjugating to antibodies that recognize PDA cancer cell proteins will be assessed. In addition, the optimal ratio of drugs conjugated to individual BPDs to achieve maximal efficacy will be established, which will be distinct from free drugs. In combination, the development of targeted multidrug-laden BPDs will promote rational combination therapies that leverage both epigenetic- and chemo-therapies to potentiate immune checkpoint inhibitors. In the third aim, BPD reporters for drug-induced apoptosis and cytotoxic T cell activity will be developed by incorporating metal-free MRI organic radical contrast agents. These reporter BPDs will be used to validate the method-of-action of combination therapies developed in Aim 1 and Aim 2. Importantly, the ability of such BPDs to rapidly report on treatment efficacies has the potential to inform subsequent treatment decisions.