DataSheet_1_In Vivo Priming of Peritoneal Tumor-Reactive Lymphocytes With a Potent Oncolytic Virus for Adoptive Cell Therapy.zip

Adoptive cell therapy (ACT) using autologous tumor infiltrating lymphocytes (TIL) achieves durable clinical benefit for patients from whom these cells can be derived in advanced metastatic melanoma but is limited in most solid tumors as a result of immune escape and exclusion. A tumor microenvironment (TME) priming strategy to improve the quantity and quality of TIL represents an important tactic to explore. Oncolytic viruses expressing immune stimulatory cytokines induce a potent inflammatory response that may enhance infiltration and activation of T cells. In this study, we examined the ability of an attenuated oncolytic vaccinia virus expressing IL15/IL15Rα (vvDD-IL15/Rα) to enhance recovery of lavage T cells in peritoneal carcinomatosis (PC). We found that intraperitoneal (IP) vvDD-IL15/Rα treatment of animals bearing PC resulted in a significant increase in cytotoxic function and memory formation in CD8+ T cells in peritoneal fluid. Using tetramers for vaccinia virus B8R antigen and tumor rejection antigen p15E, we found that the expanded population of peritoneal CD8+ T cells are specific for vaccinia or tumor with increased tumor-specificity over time, reinforced with viral clearance. Application of these vvDD-IL15/Rα induced CD8+ T cells in ACT of a lethal model of PC significantly increased survival. In addition, we found in patients with peritoneal metastases from various primary solid tumors that peritoneal T cells could be recovered but were exhausted with infrequent tumor-reactivity. If clinically translatable, vvDD-IL15/Rα in vivo priming would greatly expand the number of patients with advanced metastatic cancers responsive to T cell therapy.

过继细胞疗法（Adoptive cell therapy, ACT）采用自体肿瘤浸润淋巴细胞（autologous tumor infiltrating lymphocytes, TIL），可让晚期转移性黑色素瘤中可分离获取此类细胞的患者获得持久临床获益，但在多数实体瘤中因免疫逃逸与免疫排斥而应用受限。旨在提升TIL数量与质量的肿瘤微环境（tumor microenvironment, TME）致敏策略，是一项值得探索的重要研究方向。表达免疫刺激细胞因子的溶瘤病毒可诱导强效炎症反应，从而增强T细胞的浸润与活化。本研究探究了表达IL15/IL15Rα的减毒溶瘤痘苗病毒vvDD-IL15/Rα，对腹膜癌（peritoneal carcinomatosis, PC）模型动物腹腔灌洗液T细胞回收率的提升作用。研究发现，对携带腹膜癌的动物进行腹腔内（intraperitoneal, IP）vvDD-IL15/Rα治疗，可显著提升腹水中CD8+ T细胞的细胞毒性功能与记忆细胞形成能力。通过使用痘苗病毒B8R抗原与肿瘤排斥抗原p15E的四聚体进行检测，我们发现扩增的腹腔CD8+ T细胞可特异性识别痘苗病毒或肿瘤抗原，且随时间推移肿瘤特异性不断增强，这一效应伴随病毒清除得到进一步验证。将此类vvDD-IL15/Rα诱导的CD8+ T细胞应用于致死性腹膜癌模型的过继细胞疗法，可显著延长模型动物的生存期。此外，我们在来自多种实体瘤原发灶的腹膜转移患者中发现，尽管可回收腹腔T细胞，但此类细胞呈现耗竭表型，肿瘤反应性极低。若该疗法可实现临床转化，体内应用vvDD-IL15/Rα进行致敏，将极大拓展可响应T细胞疗法的晚期转移性癌症患者群体。