We report here the development of oncolytic adenoviruses (Ads) that have reduced toxicity, enhanced tumor tropism, produce strong antitumor response, and can overcome resistance to immune checkpoint inhibitor therapy in breast cancer. We have shown that LyP-1 receptor (p32) is highly expressed on the surface of breast cancer cells and tumors from cancer patients, and that increased stromal expression of transforming growth factor β-1 (TGFβ-1) is associated with triple-negative breast cancer. Therefore, we constructed oncolytic Ads, AdLyp.sT and mHAdLyp.sT, in which the p32-binding LyP-1 peptide was genetically inserted into the adenoviral fiber protein. Both AdLyp.sT and mHAdLyp.sT express sTGFβRIIFc, a TGFβ decoy that can inhibit TGFβ pathways. mHAdLyp.sT is an Ad5/48 chimeric hexon virus in which hypervariable regions (HVRs 1–7) of Ad5 are replaced with the corresponding Ad48 HVRs. AdLyp.sT and mHAdLyp.sT exhibited better binding, replication, and produced higher sTGFβRIIFc protein levels in breast cancer cell lines compared with Ad.sT or mHAd.sT control viruses without LyP-1 peptide modification. Systemic delivery of mHAdLyp.sT in mice resulted in reduced hepatic/systemic toxicity compared with Ad.sT and AdLyp.sT. Intravenous delivery of AdLyp.sT and mHAdLyp.sT elicited a strong antitumor response in a human MDA-MB-231 bone metastasis model in mice, as indicated by bioluminescence imaging, radiographic tumor burden, serum TRACP 5b and calcium, and body weight analyses. Furthermore, intratumoral delivery of AdLyp.sT in 4T1 model in immunocompetent mice inhibited tumor growth and metastases, and augmented anti-PD-1 and anti-CTLA-4 therapy. Based on these studies, we believe that AdLyp.sT and mHAdLyp.sT can be developed as potential targeted immunotherapy agents for the treatment of breast cancer.

中文翻译：

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LyP-1 修饰的溶瘤腺病毒靶向转化生长因子 β 抑制肿瘤生长和转移并增强乳腺癌小鼠模型中的免疫检查点抑制剂治疗。

我们在这里报告了溶瘤腺病毒 (Ads) 的发展，它们具有降低的毒性、增强的肿瘤趋向性、产生强烈的抗肿瘤反应，并且可以克服对乳腺癌免疫检查点抑制剂治疗的抵抗。我们已经证明 LyP-1 受体 (p32) 在癌症患者的乳腺癌细胞和肿瘤表面高表达，并且转化生长因子 β-1 (TGFβ-1) 的基质表达增加与三阴性乳腺癌。因此，我们构建了溶瘤 Ads AdLyp.sT 和 mHAdLyp.sT，其中 p32 结合 LyP-1 肽被基因插入到腺病毒纤维蛋白中。AdLyp.sT 和 mHAdLyp.sT 都表达 sTGFβRIIFc，这是一种可以抑制 TGFβ 通路的 TGFβ 诱饵。mHAdLyp。sT 是一种 Ad5/48 嵌合六邻体病毒，其中 Ad5 的高变区（HVR 1-7）被相应的 Ad48 HVR 替换。与没有 LyP-1 肽修饰的 Ad.sT 或 mHAd.sT 对照病毒相比，AdLyp.sT 和 mHAdLyp.sT 在乳腺癌细胞系中表现出更好的结合、复制和产生更高的 sTGFβRIIFc 蛋白水平。与 Ad.sT 和 AdLyp.sT 相比，mHAdLyp.sT 在小鼠体内的全身给药导致肝脏/全身毒性降低。生物发光成像、放射照相肿瘤负荷、血清 TRACP 5b 和钙以及体重分析表明，AdLyp.sT 和 mHAdLyp.sT 的静脉给药在小鼠的人 MDA-MB-231 骨转移模型中引发了强烈的抗肿瘤反应。此外，在免疫活性小鼠的 4T1 模型中瘤内递送 AdLyp.sT 可抑制肿瘤生长和转移，以及增强的抗 PD-1 和抗 CTLA-4 治疗。基于这些研究，我们相信 AdLyp.sT 和 mHAdLyp.sT 可以开发为治疗乳腺癌的潜在靶向免疫治疗药物。