Purpose

Treatment-associated upregulation of suppressive checkpoints and a lack of costimulatory signals compromise the antitumor efficacy of oncolytic virus immunotherapy. Therefore, we aimed to identify highly effective therapeutic targets to provide a proof-of-principle for immune checkpoint together with oncolytic virus-mediated viro-immunotherapy for cancer.

Methods

A fusion protein containing both the extracellular domain of programmed death-1 (PD-1) and the poliovirus receptor (PVR) was designed. Next, the corresponding expression fragment was inserted into the genome of a replication-competent adenovirus to generate Ad5sPD1PVR. The infection, expression, replication and oncolysis of Ad5sPD1PVR were investigated in hepatocellular carcinoma (HCC) cell lines. Immune activation and the antitumor efficacy of Ad5sPD1PVR were examined in HCC tumor models including a humanized immunocompetent mouse model.

Results

Ad5sPD1PVR effectively infected and replicated in HCC cells and secreted sPD1PVR. In a H22 ascitic HCC mouse model, intraperitoneal injection of Ad5sPD1PVR markedly recruited lymphocytes and activated antitumor immune responses. Ad5sPD1PVR exerted a profound antitumor effect on ascitic HCC. Furthermore, we found that Ad5sPD1PVR-H expressing sPD1PVR of human origin exhibited potent antitumor effects in a HCC humanized mouse model. We also found that CD8⁺ T cells mediated the antitumor effects and long-term tumor-specific immune surveillance induced by Ad5sPD1PVR. Finally, when combined with fludarabine, the antitumor efficacy of Ad5sPD1PVR was found to be further improved in the ascitic HCC model.

Conclusions

From our data we conclude that the newly designed recombinant Ad5sPD1PVR virus significantly enhances CD8⁺ T cell-mediated antitumor efficacy with long-term tumor-specific immune surveillance in hepatocellular carcinoma, and that fludarabine is a promising therapeutic partner for Ad5sPD1PVR.

中文翻译：

---

表达融合蛋白 PD1PVR 的重组腺病毒通过对肝细胞癌的长期肿瘤特异性免疫监测提高 CD8+ T 细胞介导的抗肿瘤功效

目的

抑制检查点的治疗相关上调和缺乏共刺激信号会损害溶瘤病毒免疫疗法的抗肿瘤功效。因此，我们旨在确定高效的治疗靶点，为免疫检查点和溶瘤病毒介导的癌症病毒免疫疗法提供原理证明。

方法

设计了一种同时包含程序性死亡细胞外结构域 1 (PD-1) 和脊髓灰质炎病毒受体 (PVR) 的融合蛋白。接下来，将相应的表达片段插入具有复制能力的腺病毒的基因组中以产生Ad5sPD1PVR。在肝细胞癌 (HCC) 细胞系中研究了 Ad5sPD1PVR 的感染、表达、复制和溶瘤作用。在包括人源化免疫活性小鼠模型在内的 HCC 肿瘤模型中检查了 Ad5sPD1PVR 的免疫激活和抗肿瘤功效。

结果

Ad5sPD1PVR 有效感染并在 HCC 细胞中复制并分泌 sPD1PVR。在 H22 腹水 HCC 小鼠模型中，腹腔注射 Ad5sPD1PVR 显着募集淋巴细胞并激活抗肿瘤免疫反应。Ad5sPD1PVR 对腹水型 HCC 具有显着的抗肿瘤作用。此外，我们发现表达人源 sPD1PVR 的 Ad5sPD1PVR-H 在 HCC 人源化小鼠模型中表现出有效的抗肿瘤作用。我们还发现 CD8 ⁺ T 细胞介导了 Ad5sPD1PVR 诱导的抗肿瘤作用和长期的肿瘤特异性免疫监视。最后，当与氟达拉滨联合使用时，发现 Ad5sPD1PVR 在腹水 HCC 模型中的抗肿瘤功效进一步提高。

结论

从我们的数据中，我们得出结论，新设计的重组 Ad5sPD1PVR 病毒显着增强了 CD8 ⁺ T 细胞介导的抗肿瘤功效，并在肝细胞癌中具有长期的肿瘤特异性免疫监视，并且氟达拉滨是 Ad5sPD1PVR 的有希望的治疗伙伴。