鼠李糖脂重构单域抗体Fc段生物学功能及其作用机制研究

单域抗体因其独特的性质，已经被广泛用于开发新的肿瘤治疗策略，并取得显著成效。然而，单域抗体缺乏传统抗体的可结晶片段（Fragment crystallizable, Fc），无法发挥相应的Fc段生物学功能，即一方面不能通过介导免疫效应功能高效杀伤肿瘤细胞；一方面血浆半衰期极短，难以稳定发挥药效。因此，本项目拟以抗EGFR单域抗体为研究对象，通过Sortase A介导的连接反应对其进行鼠李糖脂定点修饰，有望利用鼠李糖脂的抗鼠李糖抗体募集能力和白蛋白结合能力，达到重构单域抗体Fc段生物学功能的目的。同时，申请人将通过表面等离子共振和流式细胞术等手段对鼠李糖脂重构单域抗体Fc段生物学功能的作用机制进行探索研究，并对单域抗体-鼠李糖脂缀合物的构效关系、体内抗肿瘤活性和安全性进行综合评价分析。本研究的开展将为新一代工程抗体以及肿瘤免疫治疗策略的开发提供新思路。

Single domain antibodies (sdAbs) exhibit many advantages, consequently, sdAb-based therapeutic strategies have been widely developed and have made great achievements. However, due to the lack of fragment crystallizable (Fc) of conventional antibodies, sdAbs can not exert the corresponding Fc functions, i.e., sdAbs are unable to evoke immune functions to kill tumor cells efficiently, and have poor pharmaceutical stability with a very short serum half-life. Hence, the present project is aimed to further improve the antitumor efficiency of sdAbs, with EGFR as a target, by site-specific modification of the anti-EGFR sdAb with rhamnolipid through Sortase A-mediated ligation. We hope that the Fc functions of sdAbs will be reconstituted through the conjugation of rhamnolipid, which is capable of recruiting anti-rhamnose antibodies and binding serum albumins. Moreover, by performing surface plasmon resonance and flow cytometry analysis, we will further explore the mechanisms of action underlying the reconstitution of Fc functions of sdAbs with rhamnolipid conjugation. Finally, we will comprehensively study the structure-activity relationship of these sdAb-rhamnolipid conjugates and evaluate their anti-tumor activity and safety in vivo. We believe that this study will provide novel strategies for developing effective engineering antibodies and cancer immunotherapies.