Immune checkpoint inhibitors have advanced the treatment of melanoma. Nevertheless, a majority of patients are resistant, or develop resistance, to immune checkpoint blockade, which may be related to prevailing immune suppression by myeloid regulatory cells in the tumor microenvironment (TME). ORCA-010 is a novel oncolytic adenovirus that selectively replicates in, and lyses, cancer cells. We previously showed that ORCA-010 can activate melanoma-exposed conventional dendritic cells (cDCs). To study the effect of ORCA-010 on melanoma-conditioned macrophage development, we used an in vitro co-culture model of human monocytes with melanoma cell lines. We observed a selective survival and polarization of monocytes into M2-like macrophages (CD14⁺CD80⁻CD163⁺) in co-cultures with cell lines that expressed macrophage colony-stimulating factor. Oncolysis of these melanoma cell lines, effected by ORCA-010, activated the resulting macrophages and converted them to a more proinflammatory state, evidenced by higher levels of PD-L1, CD80, and CD86 and an enhanced capacity to prime allogenic T cells and induce a type-1 T cell response. To assess the effect of ORCA-010 on myeloid subset distribution and activation in vivo, ORCA-010 was intratumorally injected and tested for T cell activation and recruitment in the human adenovirus nonpermissive B16-OVA mouse melanoma model. While systemic PD-1 blockade in this model in itself did not modulate myeloid or T cell subset distribution and activation, when it was preceded by i.t. injection of ORCA-010, this induced an increased rate and activation state of CD8α⁺ cDC1, both in the TME and in the spleen. Observed increased rates of activated CD8⁺ T cells, expressing CD69 and PD-1, were related to both increased CD8α⁺ cDC1 rates and M1/M2 shifts in tumor and spleen. In conclusion, the myeloid modulatory properties of ORCA-010 in melanoma, resulting in recruitment and activation of T cells, could enhance the antitumor efficacy of PD-1 blockade.

中文翻译：

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溶瘤腺病毒 ORCA-010 在黑色素瘤中通过 PD-1 阻断激活促炎性骨髓细胞并促进 T 细胞募集和激活

免疫检查点抑制剂促进了黑色素瘤的治疗。然而，大多数患者对免疫检查点阻断产生抗药性或产生抗药性，这可能与肿瘤微环境 (TME) 中骨髓调节细胞的普遍免疫抑制有关。ORCA-010 是一种新型溶瘤腺病毒，可选择性地在癌细胞中复制和裂解。我们之前表明，ORCA-010 可以激活暴露于黑色素瘤的常规树突状细胞 (cDC)。为了研究 ORCA-010 对黑色素瘤条件巨噬细胞发育的影响，我们使用了人单核细胞与黑色素瘤细胞系的体外共培养模型。我们观察到单核细胞选择性存活和极化成 M2 样巨噬细胞（CD14 ⁺ CD80 ^- CD163⁺ ) 与表达巨噬细胞集落刺激因子的细胞系共培养。在 ORCA-010 的影响下，这些黑色素瘤细胞系的溶瘤作用激活了产生的巨噬细胞并将它们转化为更促炎的状态，这可以通过更高水平的 PD-L1、CD80 和 CD86 以及增强的启动同种异体 T 细胞和诱导1 型 T 细胞反应。评估 ORCA-010 对体内骨髓亚群分布和激活的影响, ORCA-010 被肿瘤内注射并在人腺病毒非许可 B16-OVA 小鼠黑色素瘤模型中测试 T 细胞活化和募集。虽然该模型中的全身性 PD-1 阻断本身并不能调节骨髓或 T 细胞亚群的分布和激活，但在它之前注射 ORCA-010 时，这会导致 CD8α ⁺ cDC1 的速率和激活状态增加，两者都在TME 和脾脏。观察到的表达 CD69 和 PD-1的活化 CD8 ^{+ T 细胞的比率增加与 CD8α +的增加有关}肿瘤和脾脏中的 cDC1 率和 M1/M2 变化。总之，ORCA-010 在黑色素瘤中的骨髓调节特性，导致 T 细胞的募集和活化，可以增强 PD-1 阻断的抗肿瘤功效。