In Situ Self‐Assembly of Artificial Topological Nanostructures Enhances In Vivo Efficacy of PCSK9 Inhibitory Peptides

Abstract Optimizing the stability and affinity of peptides in vivo is critical for their development as alternatives to approved monoclonal antibodies. In recent years, efforts in academia and industry have focused on modifying Pep2‐8, a classical antagonistic peptide targeting proprotein convertase subtilisin/kexin type 9 (PCSK9), to enhance its specificity and affinity. However, developing effective PCSK9 inhibitory peptides remains challenging, especially given the limited examples of their successful in vivo applications. Here, we designed transformable inhibitory peptide (TIP) against PCSK9 based on the modular structure of Pep2‐8. Upon encountering PCSK9, TIP undergoes in situ self‐assembly at the epidermal growth factor‐like domain A (EGF‐A) binding domain of PCSK9 to form artificial topological nanostructures (ATNs). The ATNs not only enhance peptide stability and prolong in vivo retention time but also strengthen PCSK9 binding through multivalent synergistic effects. We demonstrate that compared to Pep2‐8, TIP forms ATNs which increasing its binding affinity for PCSK9 by approximately 18.7‐fold in vitro. In high‐fat diet mouse models, TIP significantly increase hepatic LDLR levels (2.0‐fold) and reduced LDL‐C and TC levels. We envision that the in situ formation of ATNs by peptides enhances in vivo stability and affinity, which offering an approach for development as antibody alternatives in clinical.