Lyp1

LyP-1 is a short cyclic peptide used for tumor targeting and tissue penetration. The commonly cited sequence is CGNKRTRGC, cyclized by a disulfide bond between the terminal cysteines. This cyclic structure contributes to its stability and binding properties in biological environments.

LyP-1 was identified by in vivo phage-display screening for peptides that home to tumor tissue and its lymphatics. In preclinical models, it shows selective accumulation in various solid tumors and associated lymphatic vessels. The peptide binds to cells and endothelial cells that express the cell-surface receptor p32 (also known as C1QBP), and this interaction promotes internalization and penetration of the peptide into tumor tissue.

A key application of LyP-1 is as a targeting moiety for delivering imaging agents and therapeutics. It has been conjugated to a range of carriers, including liposomes, polymeric nanoparticles, quantum dots, and cytotoxic drugs, to enhance tumor visualization and selective drug delivery in animal studies.

Advantages of LyP-1 include its tumor selectivity and the ability to facilitate penetration into poorly perfused tumor regions. Limitations noted in the literature involve dependence on the level of p32 expression, potential off-target uptake in normal tissues expressing p32, and challenges related to stability, immunogenicity, and translational translation, as most work to date remains preclinical.