Kuhn Philipp, Petralla Sabrina, Dabbagh Fatemeh, Pegoretti Valentina, Muranyi Walter, Ishikawa Hiroshi, Schroten Horst, Fischer Roman, Frenzel André, Schirrmann Thomas, Rehm Markus, Schwerk Christian, Fricker Gert, Kontermann Roland, Fullstone Gavin
YUMAB GmbH, Braunschweig, Germany.
Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Heidelberg, Germany.
MAbs. 2025 Dec;17(1):2563758. doi: 10.1080/19420862.2025.2563758. Epub 2025 Sep 22.
Efficient delivery of therapeutics to the central nervous system (CNS) is one of the major challenges in treating neurological diseases due to brain barriers, which prevent entry of almost all potential therapeutic agents into the CNS. Targeting receptors that induce receptor-mediated transcytosis (RMT) across brain barriers has long been heralded as a potential solution to this problem, but this approach has yet to deliver clinical improvements for patients. Here, we set out to identify and characterize bivalent antibodies against the transferrin receptor 1 (TfR) as mediators of RMT. We identified the antibody YU904-F06 (hereafter referred to as F06) that showed efficient transcytosis as a bivalent IgG in two independent in vitro models of brain barriers. Despite its high affinity at extracellular pH levels, we determined that F06's binding to TfR was greatly reduced at lower pH levels expected during endocytic acidification. We postulated, with the support of a validated predictive mathematical model of RMT, that the pH-sensitivity of F06 allowed it to overcome the lysosomal degradation that has been previously reported for high affinity bivalent binders of TfR. Finally, we demonstrated that F06 could mediate the transcytosis of scFvs that target TREM2 or EGFRvIII as potential therapeutic cargos. In conclusion, we present a proof-of-concept antibody and rationale for the design of high affinity bivalent anti-TfR antibodies that effectively induce RMT by exploiting pH-sensitivity in binding.
由于存在脑屏障，将治疗药物有效递送至中枢神经系统（CNS）是治疗神经疾病的主要挑战之一，脑屏障会阻止几乎所有潜在治疗药物进入中枢神经系统。长期以来，靶向诱导跨脑屏障受体介导转胞吞作用（RMT）的受体一直被视为解决这一问题的潜在方案，但这种方法尚未为患者带来临床改善。在此，我们着手鉴定和表征针对转铁蛋白受体1（TfR）的二价抗体，作为RMT的介质。我们鉴定出抗体YU904-F06（以下简称F06），在两种独立的脑屏障体外模型中，该抗体作为二价IgG表现出高效的转胞吞作用。尽管F06在细胞外pH水平具有高亲和力，但我们确定在胞吞酸化预期的较低pH水平下，F06与TfR的结合大大减少。在一个经过验证的RMT预测数学模型的支持下，我们推测F06的pH敏感性使其能够克服先前报道的TfR高亲和力二价结合物的溶酶体降解。最后，我们证明F06可以介导靶向TREM2或EGFRvIII的单链抗体片段（scFv）作为潜在治疗货物的转胞吞作用。总之，我们提出了一种概念验证抗体以及设计高亲和力二价抗TfR抗体的基本原理，该抗体通过利用结合中的pH敏感性有效诱导RMT。
