LyP-1 is a cyclic peptide comprised of 9 amino acids, designed to target and bind selectively to p32 receptors that are overexpressed in a range of tumor-associated cells.

LyP-1 (8 weeks) significantly reduces plaque formation and occupation rates in treated groups, alongside increasing the apoptotic rate of macrophages from hypoxic plaques, compared to a control peptide[1]. Furthermore, for optical imaging purposes, LyP-1 is tagged with a near-infrared fluorophore, Cy5.5. In an experiment involving tumor-bearing BALB/C mice, Cy5.5-LyP-1 (0.8 nmol) was administered via the middle phalanges of the upper extremities at intervals following 4T1 cell inoculation. Recorded fluorescence intensities at days 3, 7, 14, and 21 post-inoculation were progressively higher, evidencing incremental accumulation and demonstrating rates significantly surpassing those in the contralateral lymph nodes (LNs). This co-localization of Cy5.5-LyP-1 with LYVE-1 in LNs indicates a lymphatics-specific binding affinity of the LyP-1 peptide[1].