Analytical Excellence and Program Management, Merck Serono S.p.A., Rome, Italy.
Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy.
Front Immunol. 2024 Aug 8;15:1429600. doi: 10.3389/fimmu.2024.1429600. eCollection 2024.
N-glycosylation is a post-translational modification that is highly important for the development of monoclonal antibodies (mAbs), as it regulates their biological activity, particularly in terms of immune effector functions. While typically added at the Fc level, approximately 15-25% of circulating antibodies exhibit glycosylation in the Fab domains as well. To the best of our knowledge, cetuximab (Erbitux) is the only therapeutic antibody presenting Fab glycosylation approved world-wide targeting the epidermal growth factor receptor for the treatment of metastatic-colorectal and head and neck cancers. Additionally, it can trigger antibody-dependent cell cytotoxicity (ADCC), a response that typically is influenced by N-glycosylation at Fc level. However, the role of Fab glycosylation in cetuximab remains poorly understood. Hence, this study aims to investigate the structural role of Fab glycosylation on the conformational behavior of cetuximab.
The study was performed via accelerated molecular dynamics simulations. The commercial cetuximab was compared to its form without Fab glycosylation and structural descriptors were evaluated to establish conformational differences.
The results clearly show a correlation between the Fab glycosylation and structural descriptors that may modulate the conformational freedom of the antibody, potentially affecting Fc effector functions, and suggesting a negative role of Fab glycosylation on the interaction with FcγRIIIa.
Fab glycosylation of cetuximab is the most critical challenge for biosimilar development, but the differences highlighted in this work with respect to its aglycosylated form can improve the knowledge and represent also a great opportunity to develop novel strategies of biotherapeutics.
糖基化是一种翻译后修饰，对单克隆抗体（mAbs）的发展非常重要，因为它调节其生物活性，特别是在免疫效应功能方面。虽然通常在 Fc 水平添加，但大约 15-25%的循环抗体在 Fab 结构域中也表现出糖基化。据我们所知，西妥昔单抗（Erbitux）是唯一一种在全球范围内批准用于治疗转移性结直肠癌和头颈部癌症的靶向表皮生长因子受体的 Fab 糖基化的治疗性抗体。此外，它可以触发抗体依赖性细胞细胞毒性（ADCC），这一反应通常受 Fc 水平的 N-糖基化影响。然而，西妥昔单抗 Fab 糖基化的作用仍知之甚少。因此，本研究旨在研究 Fab 糖基化对西妥昔单抗构象行为的结构作用。
该研究通过加速分子动力学模拟进行。将商业西妥昔单抗与其无 Fab 糖基化的形式进行比较，并评估结构描述符以确定构象差异。
结果清楚地表明 Fab 糖基化与结构描述符之间存在相关性，这可能调节抗体的构象自由度，潜在影响 Fc 效应功能，并表明 Fab 糖基化对与 FcγRIIIa 的相互作用具有负作用。
西妥昔单抗的 Fab 糖基化是生物类似药开发的最关键挑战，但与无糖基化形式相比，本工作中突出的差异可以提高知识水平，并代表开发新型生物治疗策略的巨大机会。
