Oncolytic virus therapy has shown activity against primary melanomas; however, its efficacy in brain metastases remains challenging, mainly because of the delivery and immunosuppressive nature of tumors in the brain. To address this challenge, we first established PTEN-deficient melanoma brain metastasis mouse models and characterized them to be more immunosuppressive compared with primary melanoma, mimicking the clinical settings. Next, we developed an allogeneic twin stem cell (TSC) system composed of two tumor-targeting stem cell (SC) populations. One SC was loaded with oncolytic herpes simplex virus (oHSV), and the other SC was CRISPR-Cas9 gene-edited to knock out nectin 1 (N1) receptor (N1 KO ) to acquire resistance to oHSV and release immunomodulators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). Using mouse models of brain metastatic BRAF V600E /PTEN −/− and BRAF V600E/wt /PTEN −/− mutant melanomas, we show that locoregional delivery of TSCs releasing oHSV and GM-CSF (TSC-G) activated dendritic cell– and T cell–mediated immune responses. In addition, our strategy exhibited greater therapeutic efficacy when compared with the existing oncolytic viral therapeutic approaches. Moreover, the TSCs composed of SC-oHSV and SC N1KO –releasing GM-CSF and single-chain variable fragment anti–PD-1 (TSC-G/P) had therapeutic efficacy in both syngeneic and patient-derived humanized mouse models of leptomeningeal metastasis. Our findings provide a promising allogeneic SC-based immunotherapeutic strategy against melanomas in the CNS and a road map toward clinical translation.

中文翻译：

---

基因编辑和工程干细胞平台推动脑转移性黑色素瘤的免疫治疗


溶瘤病毒疗法已显示出对抗原发性黑色素瘤的活性；然而，其对脑转移瘤的疗效仍然具有挑战性，主要是因为脑部肿瘤的传递和免疫抑制性质。为了应对这一挑战，我们首先建立了 PTEN 缺陷的黑色素瘤脑转移小鼠模型，并模仿临床环境，将其表征为比原发性黑色素瘤更具免疫抑制性。接下来，我们开发了由两个肿瘤靶向干细胞（SC）群体组成的同种异体双胞胎干细胞（TSC）系统。一个 SC 装载有溶瘤单纯疱疹病毒 (oHSV)，另一个 SC 经 CRISPR-Cas9 基因编辑以敲除 nectin 1 (N1) 受体 (N1) KO ）以获得对 oHSV 的抵抗力并释放免疫调节剂，例如粒细胞-巨噬细胞集落刺激因子（GM-CSF）。使用脑转移性 BRAF 小鼠模型V600E /PTEN −/−和布拉夫V600E/重量/PTEN −/−在突变黑色素瘤中，我们发现释放 oHSV 和 GM-CSF (TSC-G) 的 TSC 的局部递送激活了树突状细胞和 T 细胞介导的免疫反应。此外，与现有的溶瘤病毒治疗方法相比，我们的策略表现出更好的治疗效果。此外，TSC由SC-oHSV和SC组成N1KO – 释放 GM-CSF 和单链可变片段抗 PD-1 (TSC-G/P) 在同基因和患者来源的人源化小鼠软脑膜转移模型中均具有治疗功效。我们的研究结果提供了一种有前途的基于同种异体 SC 的针对中枢神经系统黑色素瘤的免疫治疗策略，并为临床转化提供了路线图。