Exploiting Cancer Metabolism and Drug Efflux with Bystander-Assisted Immunotherapy

抽象的。癌症耐药性的两个标志是代谢不规则和药物外流。在多种药物中—— 对于耐药性癌症，这两个过程都会削弱化疗的功效，最终导致癌症的复发。 化疗效果增加，死亡率增加。一些发展战略试图减轻 通过调节特定代谢途径或破坏药物流出来控制耐药性的影响。具体- 具体而言，这些策略包括抑制剂、干扰 RNA 和纳米医学方法。然而，一个根本 这些策略面临的心理挑战是由于破坏新陈代谢或药物外流而产生的脱靶毒性 由 P-糖蛋白 (P-gp) 介导，因为这些机制对于许多健康过程也至关重要 遍布全身。为了解决这个问题，我们的长期目标是开发一种利用 这两种耐药机制协同产生治疗性抗癌免疫反应。 我们的中心假设是，合理设计的前药可以选择癌细胞代谢和药物流出 通过我们称之为“旁观者辅助免疫”的作用机制引起抗癌免疫反应 无治疗（诱饵）。在 BAIT 中，酶引导的前药首先代谢为免疫治疗代谢物 由多重耐药癌细胞的不规则代谢引起。接下来，免疫治疗药物通过 P-gp 介导的药物流出至细胞外空间。这导致旁观者免疫细胞的激活 局部接近，从而启动抗癌免疫反应。因为BAIT需要串联代谢并且 药物流出，我们预计多重耐药表型的特异性会得到独特增强，同时表现出 这些过程。为了开发合理设计的 BAIT 前药，我们首先鉴定小分子免疫疗法 易受药物外流影响的药物。在同时进行的研究中，我们还开发了合成酶引导 调节免疫治疗活性并被表达的酶特异性去除的基团 多重耐药癌细胞的不规则代谢。结合这两个研究领域，我们生成 酶导向的 BAIT 前药，赋予多重耐药癌症免疫原性。在体外，这是反 在表达这些代谢酶和 P-gp 的免疫细胞和癌细胞系的共培养物中得到巩固。在- 在体内，我们使用前列腺癌小鼠模型系统（TRAMP-C2同种异体移植物）来证明 BAIT pro- 相对于其他药物，药物可降低毒性、减小肿瘤体积并增加无进展生存期 免疫活性小鼠的常规免疫治疗。总而言之，我们预计这项研究将 将 BAIT 作为一种治疗策略，通过耐药性来增强而不是解除武装。这是我们的 长期愿景是该策略可以广泛适用于逃避行动的多重耐药癌症 通过改变新陈代谢和药物流出的传统疗法。

ABSTRACT. Two hallmarks of drug resistance in cancers are irregular metabolism and drug efflux. In multidrug- resistant cancers, both of these processes disarm the efficacy of chemotherapeutics, ultimately resulting in de- creased chemotherapeutic efficacy and increased mortality. Several strategies in development attempt to miti- gate the effects of drug resistance by modulating specific metabolic pathways or disrupting drug efflux. Specifi- cally, these strategies include inhibitors, interference RNAs, and nanomedicine approaches. However, a funda- mental challenge to these strategies is the off-target toxicity that arises from disrupting metabolism or drug efflux mediated by P-glycoprotein (P-gp), as these mechanisms are also critical to a number of healthy processes throughout the body. To address this, our long-term objective is to develop a therapeutic strategy that exploits both of these mechanisms of drug resistance in tandem to generate a therapeutic anti-cancer immune repsonse. Our central hypothesis is that rationally designed prodrugs can co-opt cancer cell metabolism and drug efflux to cause an anti-cancer immune response via a mechanism of action we have termed Bystander Assisted Immu- noTherapy (BAIT). In BAIT, an enzyme-directed prodrug is first metabolized to an immunotherapeutic metabolite by the irregular metabolism of multidrug-resistant cancer cells. Next, the immunotherapeutic is transported, via P-gp-mediated drug efflux, to the extracellular space. This results in the activation of bystander immune cells in local proximity, which initiate an anti-cancer immune response. Because BAIT requires tandem metabolism and drug efflux, we anticipate a uniquely enhanced specificity for multidrug-resistant phenotypes that exhibit both of these processes. To develop rationally designed BAIT prodrugs, we first identify small-molecule immunothera- peutics that are susceptible to drug efflux. In concurrent studies, we also develop synthetic enzyme-directing groups that modulate the activity of immunotherapeutics and are specifically removed by enzymes expressed in the irregular metabolism of multidrug-resistant cancer cells. Combining these two research areas, we generate enzyme-directed BAIT prodrugs that confer immunogenicity to multidrug-resistant cancers. In-vitro, this is con- firmed in co-cultures of immune cells and cancer cell lines that express these metabolic enzymes and P-gp. In- vivo, we use a murine model system for prostate cancer (TRAMP-C2 allograft) to demonstrate that BAIT pro- drugs result in lowered toxicity, decreased tumor volume, and increased progression-free survival, relative to conventional immunotherapeutics in immunocompetent mice. Taken together, we envision that this research will establish BAIT as a therapeutic strategy that is enhanced, rather than disarmed, by drug resistance. It is our long-term vision that this strategy could be widely applicable to multidrug-resistant cancers that evade the action of conventional therapies through altered metabolisms and drug efflux.