The blood-brain barrier (BBB) is a major obstacle for delivering therapeutic agents to the central nervous system (CNS), posing significant challenges for treating neurological disorders. Among current strategies to improve brain drug exposure, hijacking physiological pathways involved in receptor-mediated transcytosis has emerged as a promising strategy. While targeting transferrin receptor 1 (TfR1) is widely explored, many TfR1- antibodies lack cross-species reactivity, limiting translational ...