抗体疗法显示出治疗多种疾病的巨大潜力。通常，可以安全施用的剂量受到与患病组织外的靶标相互作用所产生的副作用的限制。条件活性抗体提供额外一层选择性以提高安全性。不同的外部刺激或内部线索可以实现不同的控制策略和应用。然而，当前的抗体掩蔽策略在刺激之间的可转移性较低。在这里，我们提出了一种有条件掩蔽抗体衍生物的通用方法，并将其应用于针对多种肿瘤中癌症干细胞表达的受体的单链可变片段（scFv）。我们的策略依赖于聚合物通过化学合成的接头与工程化的半胱氨酸残基进行位点特异性缀合，该接头可以响应目标刺激而被裂解。我们表明，掩蔽效率取决于缀合位点和掩蔽的大小。优化的掩模可将抗原结合减少高达 20 倍，并且通过暴露于 365 nm 光或与实体瘤中过表达的基质金属蛋白酶一起孵育激活后，亲和力可完全恢复。这种方法为快速设计可通过任何内部或外部刺激激活的抗体提供了可能性。版权所有 © 2023。由 Elsevier B.V. 出版。

Antibody therapeutics show great potential to treat a variety of diseases. Often, the dose that can be safely administered is limited by side effects that arise from the interaction with the target outside the diseased tissue. Conditionally-active antibodies provide an additional layer of selectivity to improve safety. Distinct external stimuli or internal cues enable different control strategies and applications. However, current antibody masking strategies have low transferability across stimuli. Here we propose a versatile approach to conditionally mask antibody derivatives and its application to a single chain variable fragment (scFv) against a receptor expressed on cancer stem cells in several tumours. Our strategy relies on the site-specific conjugation of a polymer to an engineered cysteine residue through a chemically-synthesised linker that can be cleaved in response to the target stimulus. We show that the masking efficiency depends on the conjugation site and the size of the mask. An optimised mask decreases antigen binding by up to 20-fold and affinity can be fully recovered upon activation by exposure to light at 365 nm or by incubation with matrix metalloproteinases overexpressed in solid tumours. This approach opens up the possibility to rapidly engineer antibodies activatable with any internal or external stimulus.Copyright © 2023. Published by Elsevier B.V.