双膦酸盐（BPs）是保护骨骼的破骨细胞抑制剂，通常用于治疗骨质疏松症和恶性肿瘤的骨骼并发症。当作为辅助治疗时，这些药物也可以预防复发并延长绝经后的早期乳腺癌（EBC）患者的总体生存期。基于这些研究结果，含氮的辅助用双膦酸盐（N-BPs），如左旋激脲（ZOL），现已成为高危EBC患者的标准护理，但缺乏关联受益的生物标志物，并且疗效较低。已经证明BPs具有抗肿瘤活性，但它们在EBC中提供益处的机制尚不明确。我们使用稳定转染的4T1乳腺癌细胞与CD73抑制（sh-CD73）或对照细胞（sh-NT）进行实验。我们使用了两种小鼠模型，比较了ZOL对肿瘤生长和浸润淋巴细胞（TILs）进入肿瘤和肺转移的影响。我们使用抗CD20抗体进行了B细胞耗尽。sh-CD73 4T1细胞对体外n-BPs的生长抑制效果明显更敏感。然而，在体内，尽管ZOL诱导的生长抑制在肿瘤组之间相似，ZOL可以增强CD73抑制下调的同位型肿瘤中的B和T淋巴细胞浸润。类似的趋势在肺转移中也被检测到。在sh-NT肿瘤中，B细胞耗尽增强了ZOL诱导的肿瘤生长抑制，但在sh-CD73肿瘤中没有这种增强效应。作为内部对照，ZOL对骨骼的效果在携带两种肿瘤的小鼠中是相似的。综上所述，这些结果表明ZOL可以调节初级肿瘤和转移灶中的TILs。我们的结果进一步证明B细胞可能会对抗ZOL的生长抑制效果。然而，所有ZOL诱导的TIL效应可能会受肿瘤的免疫调节特性的影响。©2023 Petruk、Siddiqui、Tadayon、Määttä、Mattila、Jukkola、Sandholm和Selander。

Bisphosphonates (BPs) are bone-protecting osteoclast inhibitors, typically used in the treatment of osteoporosis and skeletal complications of malignancies. When given in the adjuvant setting, these drugs may also prevent relapses and prolong overall survival in early breast cancer (EBC), specifically among postmenopausal patients. Because of these findings, adjuvant nitrogen-containing BPs (N-BPs), such as zoledronate (ZOL), are now the standard of care for high-risk EBC patients, but there are no benefit-associated biomarkers, and the efficacy remains low. BPs have been demonstrated to possess anti-tumor activities, but the mechanisms by which they provide the beneficial effects in EBC are not known.We used stably transfected 4T1 breast cancer cells together with suppression of CD73 (sh-CD73) or control cells (sh-NT). We compared ZOL effects on tumor growth and infiltrating lymphocytes (TILs) into tumors and lung metastases using two mouse models. B cell depletion was performed using anti-CD20 antibody.Sh-CD73 4T1 cells were significantly more sensitive to the growth inhibitory effects of n-BPs in vitro. However, while ZOL-induced growth inhibition was similar between the tumor groups in vivo, ZOL enhanced B and T lymphocyte infiltration into the orthotopic tumors with down-regulated CD73. A similar trend was detected in lung metastases. ZOL-induced tumor growth inhibition was found to be augmented with B cell depletion in sh-NT tumors, but not in sh-CD73 tumors. As an internal control, ZOL effects on bone were similar in mice bearing both tumor groups.Taken together, these results indicate that ZOL modifies TILs in breast cancer, both in primary tumors and metastases. Our results further demonstrate that B cells may counteract the growth inhibitory effects of ZOL. However, all ZOL-induced TIL effects may be influenced by immunomodulatory characteristics of the tumor.Copyright © 2023 Petruk, Siddiqui, Tadayon, Määttä, Mattila, Jukkola, Sandholm and Selander.