Gurbatri Candice R, Lia Ioana, Vincent Rosa, Coker Courtney, Castro Samuel, Treuting Piper M, Hinchliffe Taylor E, Arpaia Nicholas, Danino Tal
Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
Department of Comparative Medicine, University of Washington, Seattle, WA 98195, USA.
Sci Transl Med. 2020 Feb 12;12(530). doi: 10.1126/scitranslmed.aax0876.
Checkpoint inhibitors have revolutionized cancer therapy but only work in a subset of patients and can lead to a multitude of toxicities, suggesting the need for more targeted delivery systems. Because of their preferential colonization of tumors, microbes are a natural platform for the local delivery of cancer therapeutics. Here, we engineer a probiotic bacteria system for the controlled production and intratumoral release of nanobodies targeting programmed cell death-ligand 1 (PD-L1) and cytotoxic T lymphocyte-associated protein-4 (CTLA-4) using a stabilized lysing release mechanism. We used computational modeling coupled with experimental validation of lysis circuit dynamics to determine the optimal genetic circuit parameters for maximal therapeutic efficacy. A single injection of this engineered system demonstrated an enhanced therapeutic response compared to analogous clinically relevant antibodies, resulting in tumor regression in syngeneic mouse models. Supporting the potentiation of a systemic immune response, we observed a relative increase in activated T cells, an abscopal effect, and corresponding increases in systemic T cell memory populations in mice treated with probiotically delivered checkpoint inhibitors. Last, we leveraged the modularity of our platform to achieve enhanced therapeutic efficacy in a poorly immunogenic syngeneic mouse model through effective combinations with a probiotically produced cytokine, granulocyte-macrophage colony-stimulating factor (GM-CSF). Together, these results demonstrate that our engineered probiotic system bridges synthetic biology and immunology to improve upon checkpoint blockade delivery.
检查点抑制剂彻底改变了癌症治疗方式，但仅对一部分患者有效，且会引发多种毒性反应，这表明需要更具靶向性的递送系统。由于微生物能够优先在肿瘤中定殖，因此它们是局部递送癌症治疗药物的天然平台。在此，我们构建了一种益生菌系统，利用稳定的裂解释放机制，实现对靶向程序性细胞死亡配体1（PD-L1）和细胞毒性T淋巴细胞相关蛋白4（CTLA-4）的纳米抗体进行可控生产和瘤内释放。我们通过计算建模并结合裂解电路动力学的实验验证，来确定实现最大治疗效果的最佳基因电路参数。与类似的临床相关抗体相比，单次注射这种工程系统显示出增强的治疗反应，在同基因小鼠模型中导致肿瘤消退。为支持全身免疫反应的增强，我们在用益生菌递送的检查点抑制剂治疗的小鼠中观察到活化T细胞相对增加、远隔效应以及全身T细胞记忆群体相应增加。最后，我们利用平台的模块化特性，通过与益生菌产生的细胞因子粒细胞-巨噬细胞集落刺激因子（GM-CSF）有效组合，在免疫原性较差的同基因小鼠模型中实现了增强的治疗效果。总之，这些结果表明，我们的工程益生菌系统将合成生物学和免疫学相结合，改进了检查点阻断递送。
