Department of Hematology and Oncology, Children's Hospital, University Hospital Tuebingen, 72076 Tuebingen, Germany.
Cells. 2021 Apr 26;10(5):1020. doi: 10.3390/cells10051020.
Melanoma is the most lethal of all skin-related cancers with incidences continuously rising. Novel therapeutic approaches are urgently needed, especially for the treatment of metastasizing or therapy-resistant melanoma. CAR-modified immune cells have shown excellent results in treating hematological malignancies and might represent a new treatment strategy for refractory melanoma. However, solid tumors pose some obstacles for cellular immunotherapy, including the identification of tumor-specific target antigens, insufficient homing and infiltration of immune cells as well as immune cell dysfunction in the immunosuppressive tumor microenvironment (TME).
In order to investigate whether CAR NK cell-based immunotherapy can overcome the obstacles posed by the TME in melanoma, we generated CAR NK-92 cells targeting CD276 (B7-H3) which is abundantly expressed in solid tumors, including melanoma, and tested their effectivity in vitro in the presence of low pH, hypoxia and other known factors of the TME influencing anti-tumor responses. Moreover, the CRISPR/Cas9-induced disruption of the inhibitory receptor NKG2A was assessed for its potential enhancement of NK-92-mediated anti-tumor activity.
CD276-CAR NK-92 cells induced specific cytolysis of melanoma cell lines while being able to overcome a variety of the immunosuppressive effects normally exerted by the TME. NKG2A knock-out did not further improve CAR NK-92 cell-mediated cytotoxicity.
The strong cytotoxic effect of a CD276-specific CAR in combination with an "off-the-shelf" NK-92 cell line not being impaired by some of the most prominent negative factors of the TME make CD276-CAR NK-92 cells a promising cellular product for the treatment of melanoma and beyond.
黑色素瘤是所有皮肤相关癌症中最致命的一种，发病率持续上升。迫切需要新的治疗方法，特别是对于转移性或治疗抵抗性黑色素瘤的治疗。CAR 修饰的免疫细胞在治疗血液恶性肿瘤方面显示出了优异的效果，可能代表了一种治疗难治性黑色素瘤的新策略。然而，实体肿瘤为细胞免疫治疗带来了一些障碍，包括鉴定肿瘤特异性靶抗原、免疫细胞归巢和浸润不足以及免疫抑制肿瘤微环境（TME）中的免疫细胞功能障碍。
为了研究 CAR NK 细胞免疫疗法是否可以克服黑色素瘤 TME 带来的障碍，我们构建了靶向 CD276（B7-H3）的 CAR NK-92 细胞，该抗原在包括黑色素瘤在内的实体肿瘤中大量表达，并在存在低 pH 值、缺氧和其他已知影响抗肿瘤反应的 TME 因素的情况下，在体外测试其有效性。此外，还评估了 CRISPR/Cas9 诱导的抑制性受体 NKG2A 破坏对 NK-92 介导的抗肿瘤活性的潜在增强作用。
CD276-CAR NK-92 细胞诱导了黑色素瘤细胞系的特异性细胞溶解，同时能够克服 TME 通常施加的多种免疫抑制作用。NKG2A 敲除并没有进一步提高 CAR NK-92 细胞介导的细胞毒性。
CD276 特异性 CAR 与“现成的”NK-92 细胞系的强大细胞毒性作用相结合，不受 TME 中一些最显著的负性因素的影响，这使得 CD276-CAR NK-92 细胞成为治疗黑色素瘤及其他疾病的有前途的细胞产品。
