Developing polycistronic replication-defective herpes simplex virus vectors as immunotherapeutic tools for treating melanoma

摘要 最近FDA批准了一种改良的复制型单纯疱疹病毒（HSV），talimogene laherparepvec（T- 编码GM-CSF用于治疗黑色素瘤的VEC是溶瘤病毒治疗领域的突破。 虽然T-VEC的批准是革命性的，但仍有几个方面需要改进。第一，live 病毒不能安全地给予免疫功能低下的患者，包括那些接受类固醇， 传播性疱疹感染的风险。其次，GM-CSF可以诱导免疫抑制性骨髓细胞， 可能不是最佳的插入物。第三，仅一种细胞因子有效载荷的选择是有限的。为此，我们的实验室 利用一种称为d106 S的非复制型HSV病毒，可作为治疗的安全病毒载体 因为它不能复制。HSV-1 d106 S最初被设计为用于瞬时免疫的疫苗载体。 表达的货物，我们已经重新利用作为一个非裂解载体的局部交付的IL-12，一个有效的 能够组织针对肿瘤的Th 1应答的细胞因子。然而，由于IL-12的多效性作用， 剂量限制性毒性常常成为有效治疗的障碍。我们的复制缺陷型d106 S病毒 在肿瘤环境中局部释放大量IL-12，其与I型IFN应答协同作用 由病毒引起的。我们已经表明，d106 S-IL 12诱导肿瘤消退和长期稳定的肿瘤生长。 小鼠B16黑色素瘤免疫平衡这些结果是有希望的，并表明d106 S载体可以 递送免疫活性物质并诱导已建立的肿瘤缩小。有趣的是，大多数老鼠 并没有完全清除肿瘤，而是建立了一个平衡阶段。停止治疗最终导致肿瘤 结果我们已经分析了d106 S-IL 12在几个时间点诱导的免疫应答， 确定了几个潜在干预的关键节点，包括阻断先天性炎症细胞因子IL-1β， TNFα和IL-6。我们还证实了来自编码CD 8 + T细胞的d106 S载体的CD 8 + T细胞浸润增加。 趋化因子CXCL 13。基于d106 S-IL 12的高效力，我们建议添加细胞因子 非复制型多顺反子载体内的阻断或趋化因子分泌将允许串联表达， 局部肿瘤的消退和甚至更强的CD 8 + T细胞应答的引发。这种非复制性 多顺反子HSV-1将是第一个这样的，我们的研究将提供新的见解之间的协同作用， IL-12的不同负性和正性调节因子以及这些细胞因子/趋化因子如何影响抗肿瘤免疫 记忆形成

ABSTRACT The recent FDA-approval of a modified, replicating herpes simplex virus (HSV), talimogene laherparepvec (T- VEC), encoding GM-CSF for the treatment of melanoma, was a breakthrough in the field of oncolytic virotherapy. Although the approval of T-VEC was revolutionary, there are still several areas for improvement. First, the live virus cannot be safely administered to immunocompromised patients, including those receiving steroids, without risk of disseminated herpes infection. Second, GM-CSF can induce immune-suppressive myeloid cells and is likely not the optimal insert. Third, the choice of only one cytokine payload is limiting. To this end, our lab has made use of a non-replicating HSV virus, termed d106S, that can serve as a safe viral vector for the treatment of cancers because it is non-replicating. HSV-1 d106S was originally designed as a vaccine vector for transient expression of cargoes, which we have repurposed as a non-lytic vector for local delivery of IL-12, a potent cytokine capable of organizing a Th1 response against tumors. However, due to the pleiotropic effects of IL-12, dose-limiting toxicities often become a barrier to effective treatment. Our replication-defective d106S virus releases a large burst of IL-12 locally within the tumor environment, which synergizes with a type I IFN response induced by the virus. We have shown that d106S-IL12 induces regression of tumors and long-term stable immune equilibrium in murine B16 melanoma. These results are promising and show that the d106S vector can deliver immunotherapeutic cargo and induce shrinkage of established tumors. Intriguingly, the majority of mice do not fully clear their tumors but establish an equilibrium phase. Withdrawal of therapy eventually leads to tumor outgrowth. We have profiled the immune response induced by d106S-IL12 at several time points, and have identified several key nodes of potential intervention, including blockade of innate inflammatory cytokines IL-1β, TNFα and IL-6. We have also demonstrated increased CD8+ T cell infiltration from a d106S vector encoding the chemokine CXCL13. Based on the high potency of d106S-IL12, and we propose that addition of cytokine blockade or chemokine secretion within a non-replicating polycistronic vector will allow for tandem expression, regression of local tumors and priming of an even more robust CD8+ T cell response. This non-replicating, polycistronic HSV-1 would be one of the first of its kind, and our study will give new insight into synergy between different negative and positive regulators of IL-12 and how these cytokines/chemokines affect anti-tumor immune memory formation.