B cell maturation antigen (BCMA) is a membrane-bound receptor that is overexpressed on multiple myeloma cells and can be targeted with biotherapeutics. Soluble shed forms of membrane-associated receptors in circulation can act as a drug sink, especially when it is present in high molar ratio compared to drug concentration, potentially derailing the intended pharmacological mechanism and impacting pharmacokinetic (PK) measurements and efficacious dose predictions. In this study, we present a bioanalytical strategy for assessing dynamic levels of total soluble BCMA before and during treatment with a bispecific antibody targeting BCMA and CD3. Implementation of a ligand binding assay was not successful due to extensive bispecific antibody interference. Instead, we explored two types of immunoaffinity (IA) liquid chromatography–tandem mass spectrometry (LC-MS/MS) assays, one at the protein level and one at the surrogate peptide level. Ultimately, the protein-level IA-LC-MS/MS method was optimized for use in a cynomolgus monkey PK/pharmacodynamic study. In addition, we demonstrated that the method was easily adapted for use with human samples in preparation for translation to the clinic. This work demonstrates the benefit of flexibility and agility in bioanalytical method development in early drug development. Multiplatform suitability assessments enable rapid, resource-sparing identification and qualification of clinically translatable assays. We recommend early adoption of this strategy to provide enough time for critical reagent development and assay validation for analysis of shed targets.

中文翻译：

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一种用于测量总循环棚靶受体的灵活多平台生物分析策略：在双特异性抗体药物存在下对可溶性 B 细胞成熟抗原水平的应用

B 细胞成熟抗原 (BCMA) 是一种膜结合受体，在多发性骨髓瘤细胞上过度表达，可作为生物治疗药物的靶点。循环中可溶性脱落形式的膜相关受体可以充当药物吸收器，特别是当它与药物浓度相比以高摩尔比存在时，可能会破坏预期的药理学机制并影响药代动力学 (PK) 测量和有效剂量预测。在这项研究中，我们提出了一种生物分析策略，用于在使用靶向 BCMA 和 CD3 的双特异性抗体治疗之前和期间评估总可溶性 BCMA 的动态水平。由于广泛的双特异性抗体干扰，配体结合测定的实施不成功。反而，我们探索了两种类型的免疫亲和 (IA) 液相色谱-串联质谱 (LC-MS/MS) 分析，一种在蛋白质水平，一种在替代肽水平。最终，蛋白质水平 IA-LC-MS/MS 方法被优化用于食蟹猴 PK/药效学研究。此外，我们证明该方法很容易适用于人类样本，为临床翻译做准备。这项工作证明了在早期药物开发中生物分析方法开发的灵活性和敏捷性的好处。多平台适用性评估能够快速、节省资源地识别和鉴定临床可翻译的检测方法。我们建议尽早采用此策略，以便为分析脱落目标的关键试剂开发和测定验证提供足够的时间。