意大利卡拉布里亚大学Tommaso Angelone等研究人员合作发现，曲妥珠单抗的重组抗原结合片段（Fab）在成人心肌细胞中表现出较低的细胞毒性特征。2024年10月16日，《中国药理学报》杂志在线发表了这项成果。

研究人员表示，片段结晶γ受体（FcγR）介导多种细胞反应，并对心血管有重要影响。它们参与了曲妥珠单抗（TRZ）的抗癌活性。TRZ是一种重组的人源化单克隆抗体，通过干扰人表皮生长因子受体2（HER2）来阻止其在心肌细胞中的生理功能，这导致了TRZ临床应用中常见的心脏并发症。

研究人员探讨了FcγR在TRZ心脏毒性中的作用。研究人员使用TRZ的重组抗原结合片段（Fab）（rFab-HER2）来检验Fc区的缺失是否能减少心肌细胞毒性，但同时保留TRZ抑制HER2的能力。与TRZ相比，暴露于rFab-HER2的AC16人类成人心室心肌细胞不易受到损伤和死亡。具体而言，TRZ在较低浓度（150 µg/mL，约1 µM）下表现出细胞毒性，而rFab-HER2在较高浓度（250 µg/mL，约5 µM）时才表现出相应的毒性。与TRZ类似，rFab-HER2能够调节心肌细胞中的HER2水平（但不会对HER2表达极低或不表达的BJ人类成纤维细胞产生细胞毒性作用），并抑制下游的ERK/AKT级联反应。

然而，rFab-HER2未改变心肌细胞线粒体动态平衡，也未影响细胞凋亡和炎症反应，同时限制了细胞质和线粒体中的ROS（活性氧）指标。相反，Fc区（50−250 μg/mL）对心肌细胞产生了直接的细胞毒性作用（但对缺乏Fc受体的人类成纤维细胞没有影响）。TRZ（150 μg/mL）显著上调了心肌细胞中FcγRIIA（在TRZ诱导的抗体依赖性细胞毒性中高度参与的FcγR）的表达水平，而Fab片段（150 μg/mL）没有此效果。

这些研究结果表明，Fc区在TRZ诱导的心肌细胞毒性中起着重要的致病作用。此外，靶向FcγRIIA可能有助于减少TRZ治疗中的脱靶效应。

附：英文原文

Title: A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor

Author: De Bartolo, Anna, Romeo, Naomi, Marrone, Alessandro, Rago, Vittoria, Granieri, Maria Concetta, Vommaro, Maria Luigia, Cupelli, Arianna, Cerra, Maria Carmela, Indiveri, Cesare, Ronca, Raffaele, Cantile, Maria, Sanna, Riccardo, Rocca, Carmine, Angelone, Tommaso

Issue&Volume: 2024-10-16

Abstract: Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ’s ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150μg/mL, corresponding to ~1μM) compared to rFab-HER2 (250μg/mL, corresponding to ~5μM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50250μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

DOI: 10.1038/s41401-024-01397-3

Source: https://www.nature.com/articles/s41401-024-01397-3