DataSheet_1_Characterization of anti-drug antibody responses to the T-cell engaging bispecific antibody cibisatamab to understand the impact on exposure.docx

An appropriately designed pharmacokinetic (PK) assay that is sensitive for anti-drug antibody (ADA) impact on relevant exposure is an alternative strategy to understand the neutralizing potential of ADAs. However, guidance on how to develop such PK assays and how to confirm the functional ADA impact on exposure is missing. Here, the PK assay of a T-cell-engaging bispecific antibody, cibisatamab, was developed based on its mechanism of action (MoA). Using critical monoclonal anti-idiotypic (anti-ID) antibody positive controls as ADA surrogates, the impact on exposure was evaluated pre-clinically. In a phase I clinical trial (NCT02324257), initial data suggest that the combination of ADA and PK assays for correlation of the ADA response with cibisatamab exposure. To understand the neutralizing potential of patient-derived ADAs on drug activity, advanced ADA characterization has been performed. Structural binding analysis of ADAs to antibody domains of the drug and its impact on targeting were assessed. For this purpose, relevant patient ADA binding features were identified and compared with the specific monoclonal anti-ID antibody-positive controls. Comparable results of target binding inhibition and similar impacts on exposure suggest that the observed reduction of Cmax and Ctrough levels in patients is caused by the neutralizing potential of ADAs and allows a correlation between ADA response and loss of exposure. Therefore, the described study provides important functional aspects for the development of an appropriately designed PK assay for bispecific antibodies as an alternative option towards understanding the neutralizing ADA impact on exposure.

一款可灵敏检测抗药抗体（anti-drug antibody, ADA）对药物相关暴露量影响的合理设计型药代动力学（pharmacokinetic, PK）测定法，是解析ADA中和潜力的替代研究策略。但目前尚缺乏关于此类PK测定法的开发规范，以及确证ADA对药物暴露量产生功能性影响的相关指导原则。本研究基于T细胞衔接型双特异性抗体西萨妥单抗（cibisatamab）的作用机制（mechanism of action, MoA），开发了其专属PK测定法。以关键单克隆抗独特型（anti-idiotypic, anti-ID）抗体作为ADA替代阳性对照，在临床前阶段评估了其对药物暴露量的影响。在一项I期临床试验（NCT02324257）中，初步数据表明，联合应用ADA与PK测定法可实现ADA应答与西萨妥单抗暴露量的相关性分析。为解析患者来源ADA对药物活性的中和潜力，研究团队开展了精细化的ADA表征工作：对ADA与药物抗体结构域的结构结合特征，及其对药物靶向能力的影响进行了评估。为此，研究人员鉴定了患者来源ADA的关键结合特性，并与前述单克隆抗独特型抗体阳性对照进行了比对分析。二者在靶标结合抑制效果及对药物暴露量的影响方面表现一致，提示患者体内观测到的峰浓度（Cmax）与谷浓度（Ctrough）水平下降，系ADA的中和活性所致，同时证实了ADA应答与药物暴露量损失之间存在相关性。综上，本研究为双特异性抗体的合理设计型PK测定法开发提供了重要的功能性依据，为解析ADA对药物暴露量的中和影响提供了可行的替代方案。