Aberrant TGFβ signaling is linked to metastasis and tumor immune escape of many cancers including metastatic triple negative breast cancer (mTNBC). Previously, we have found that oncolytic adenoviruses expressing a TGFβ signaling inhibitory protein (sTGFβRIIFc) induced immune activation in a mouse TNBC (4T1) immunocompetent subcutaneous model with intratumoral injection. Systemic administration of adenoviruses can be a superior route to treat mTNBC but faces the challenges of increased toxicity and viral clearance. Thus, we created a liver-de-targeted sTGFβRIIFc- and LyP-1 peptide-expressing adenovirus (mHAdLyp.sT) with enhanced breast cancer cell tropism. Its safety and immune response features were profiled in the 4T1 model. Our data showed that the systemic administration of mHAdLyp.sT resulted in reduced hepatic and systemic toxicity. mHAdLyp.sT was also effective in increasing Th1 cytokines and anti-tumor cell populations by cytokine analysis, spleen/tumor qRT-PCR, and flow cytometry. We further tested the therapeutic effects of mHAdLyp.sT alone and in combination with immune checkpoint inhibitors (ICIs). mHAdLyp.sT alone and with all ICI combinations elicited significant inhibition of lung metastasis by histological analysis. When mHAdLyp.sT was combined with both anti-PD-1 and anti-CTLA-4 antibodies, primary 4T1 tumor growth was also significantly inhibited. We are confident in advancing this new treatment option for mTNBC.

异常的 TGFβ 信号传导与许多癌症的转移和肿瘤免疫逃逸有关，包括转移性三阴性乳腺癌 (mTNBC)。此前，我们发现表达TGFβ信号抑制蛋白（sTGFβRIIFc）的溶瘤腺病毒通过瘤内注射在小鼠TNBC（4T1）免疫活性皮下模型中诱导免疫激活。腺病毒的全身给药可能是治疗 mTNBC 的最佳途径，但面临毒性和病毒清除增加的挑战。因此，我们创建了一种表达肝脏去靶向 sTGFβRIIFc 和 LyP-1 肽的腺病毒 (mHAdLyp.sT)，其具有增强的乳腺癌细胞趋向性。4T1 模型描述了其安全性和免疫反应特征。我们的数据表明，mHAdLyp.sT 的全身给药可降低肝脏和全身毒性。通过细胞因子分析、脾/肿瘤 qRT-PCR 和流式细胞术，mHAdLyp.sT 还可有效增加 Th1 细胞因子和抗肿瘤细胞群。我们进一步测试了 mHAdLyp.sT 单独使用以及与免疫检查点抑制剂 (ICIs) 联合使用的治疗效果。通过组织学分析，单独使用 mHAdLyp.sT 以及与所有 ICI 组合可显着抑制肺转移。当mHAdLyp.sT与抗PD-1和抗CTLA-4抗体联合时，原发4T1肿瘤的生长也被显着抑制。我们对推进 mTNBC 的这一新治疗方案充满信心。