Zhang Yenan, He Bohao, Zou Peng, Wu Mengdi, Wei Min, Xu Chuning, Dong Jie, Wei Jiwu
State Key Laboratory of Pharmaceutical Biotechnology, The Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, Jiangsu, China.
Jiangsu Key Laboratory of Molecular Medicine, Nanjing University Medical School, Nanjing, Jiangsu, China.
J Immunother Cancer. 2025 Apr 1;13(4):e010767. doi: 10.1136/jitc-2024-010767.
The pleiotropic roles of tumor-associated macrophages (TAMs) render them attractive targets in antitumor drug development. CD47/SIRPα (signal regulatory protein alpha) and CD24/Siglec-10 (sialic acid-binding immunoglobulin-like lectin 10) signaling pathways have been found to suppress macrophage phagocytosis of malignant cells. Systemic blockade of CD47/SIRPα has shown severe side effects. Intratumoral delivery of a CD47 inhibitor by oncolytic viruses (OVs) may circumvent this hurdle.
To identify the characteristics of recombinant adenovirus (AdV)-SIRPα/Siglec-10, we conducted CCK8 assay, quantitative PCR, western blot, competitive binding assay, in vitro cytotoxicity assay, ELISA and phagocytosis assay. We investigated the antitumor immune responses of AdV-SIRPα/Siglec-10 using flow cytometry, various tumor-bearing mouse models, humanized tumor-bearing mouse models, immune cell depletion, RNA sequencing, and in vitro T cell activation assay.
Here, we developed a novel AdV encoding a fusion protein composed of the extracellular domains of murine or human SIRPα and Siglec-10 (SIRPα/Siglec-10), termed AdV-mSS or AdV-huSS. The SIRPα/Siglec-10 was effectively secreted by cells infected with AdV-mSS and functioned as a dual blocker of CD47 and CD24, thereby significantly enhancing macrophage phagocytosis. In a series of tumor models, including subcutaneous and ascitic H22 hepatocellular carcinoma (HCC), subcutaneous Hepa1-6 HCC, MC38 colorectal carcinoma, and Lewis lung carcinoma, AdV-mSS treatment markedly enhanced antitumor efficacy. Mechanistically, AdV-mSS reprogrammed TAMs toward an antitumor phenotype and enhanced the expression of major histocompatibility complex (MHC)-I/II, promoting CD8+T cell proliferation and activation. Depletion of either macrophages or CD8+T cells abrogated the antitumor efficacy of AdV-mSS. Similarly, in a humanized LM3 HCC mouse model, AdV-huSS significantly inhibited tumor growth and prolonged survival.
Dual SIRPα/Siglec-10 inhibitor delivered intratumorally by AdV not only reinvigorated the TAM-CD8+T cell axis but also potentially reduced the risk of off-target effects. Further investigation of AdV-huSS in patients with cancer is warranted in the near future.
肿瘤相关巨噬细胞（TAM）的多效性作用使其成为抗肿瘤药物研发中具有吸引力的靶点。已发现CD47/SIRPα（信号调节蛋白α）和CD24/Siglec-10（唾液酸结合免疫球蛋白样凝集素10）信号通路可抑制巨噬细胞对恶性细胞的吞噬作用。CD47/SIRPα的全身阻断已显示出严重的副作用。通过溶瘤病毒（OV）在肿瘤内递送CD47抑制剂可能会克服这一障碍。
为了鉴定重组腺病毒（AdV）-SIRPα/Siglec-10的特性，我们进行了CCK8测定、定量PCR、蛋白质印迹、竞争结合测定、体外细胞毒性测定、酶联免疫吸附测定和吞噬作用测定。我们使用流式细胞术、各种荷瘤小鼠模型、人源化荷瘤小鼠模型、免疫细胞耗竭、RNA测序和体外T细胞活化测定来研究AdV-SIRPα/Siglec-10的抗肿瘤免疫反应。
在此，我们开发了一种新型AdV，其编码由小鼠或人SIRPα和Siglec-10的细胞外结构域组成的融合蛋白（SIRPα/Siglec-10），称为AdV-mSS或AdV-huSS。SIRPα/Siglec-10由感染AdV-mSS的细胞有效分泌，并作为CD47和CD24的双重阻断剂发挥作用，从而显著增强巨噬细胞的吞噬作用。在一系列肿瘤模型中，包括皮下和腹水型H22肝细胞癌（HCC）、皮下Hepa1-6 HCC、MC38结直肠癌和Lewis肺癌，AdV-mSS治疗显著增强了抗肿瘤疗效。从机制上讲，AdV-mSS将TAM重编程为抗肿瘤表型，并增强主要组织相容性复合体（MHC）-I/II的表达，促进CD8+T细胞增殖和活化。巨噬细胞或CD8+T细胞的耗竭消除了AdV-mSS的抗肿瘤疗效。同样，在人源化LM3 HCC小鼠模型中，AdV-huSS显著抑制肿瘤生长并延长生存期。
通过AdV在肿瘤内递送的双重SIRPα/Siglec-10抑制剂不仅重振了TAM-CD8+T细胞轴，还可能降低脱靶效应的风险。在不久的将来有必要对癌症患者中的AdV-huSS进行进一步研究。
