Abstract

Immunotherapies are changing the landscape of melanoma treatment, but 70% of the melanoma patients have no response to immune checkpoint inhibitors or oncolytic virus therapy. Thus, novel formulations are needed to improve the population benefiting from immunotherapy. Here, we report a combined therapeutic modality based on oncolytic virus nanovesicles composed of CaCl₂, oncolytic virus Ad5, lecithin and cholesterol (Lipo-Cap–Ad5) with immune checkpoint blockade (anti-PD-1 antibody). We investigated in vivo antitumour activity, systemic toxicity and mechanism of antitumour immune responses of Lipo-Cap–Ad5 + anti-PD-1 blockade, in a murine B16F10 tumour xenograft model. Through a series of in vivo studies, we found that Lipo-Cap–Ad5 in combination with anti-PD-1 blockade drastically reduced the tumour growth by 76.6%, and prolonged animals’ survival with no obvious toxicity observed in heart, liver and kidney. The combination therapy facilitates tumour infiltration of effector CD4⁺, CD8⁺ T cells and increases secretion of TNF-α and IFN-γ. Therefore, Lipo-Cap–Ad5 in combination with anti-PD-1 blockade can potentiate and activate the immune system synergistically, ultimately creating a pro-inflammatory environment. These results suggest that combination immunotherapy of Lipo-Cap–Ad5 and anti-PD-1 blockade developed in this study has promising applications to enhance therapeutic efficacy with the potential of being translated into clinical practice.

摘要

免疫疗法正在改变黑色素瘤治疗的格局，但 70% 的黑色素瘤患者对免疫检查点抑制剂或溶瘤病毒疗法没有反应。因此，需要新的制剂来改善受益于免疫疗法的人群。在这里，我们报告了一种基于溶瘤病毒纳米囊泡的联合治疗方式，该溶瘤病毒纳米囊泡由 CaCl ₂、溶瘤病毒 Ad5、卵磷脂和胆固醇（Lipo-Cap–Ad5）组成，并具有免疫检查点阻断（抗 PD-1 抗体）。我们在小鼠 B16F10 肿瘤异种移植模型中研究了 Lipo-Cap–Ad5 + 抗 PD-1 阻断的体内抗肿瘤活性、全身毒性和抗肿瘤免疫反应机制。通过一系列体内研究中，我们发现 Lipo-Cap-Ad5 与抗 PD-1 阻断剂联合使用可显着降低肿瘤生长 76.6%，并延长动物的存活时间，并且在心脏、肝脏和肾脏中未观察到明显的毒性。联合治疗促进效应 CD4 ⁺、CD8 ⁺ T 细胞的肿瘤浸润并增加 TNF-α 和 IFN-γ 的分泌。因此，Lipo-Cap-Ad5 结合抗 PD-1 阻断剂可以协同增强和激活免疫系统，最终创造一个促炎环境。这些结果表明，本研究中开发的 Lipo-Cap-Ad5 和抗 PD-1 阻断剂的联合免疫疗法在提高治疗效果方面具有广阔的应用前景，并具有转化为临床实践的潜力。