Targeted Delivery of Paclitaxel to EphA2-Expressing Cancer Cells

Purpose: YSA is an EphA2-targeting peptide that effectively delivers anticancer agents to prostate cancer tumors. Here, we report on how we increased the drug-like properties of this delivery system. Experimental Design: By introducing non-natural amino acids, we have designed two new EphA2 targeting peptides: YNH, where norleucine and homoserine replace the two methionine residues of YSA, and dYNH, where a D-tyrosine replaces the L-tyrosine at the first position of the YNH peptide. We describe the details of the synthesis of YNH and dYNH paclitaxel conjugates (YNH-PTX and dYNH-PTX) and their characterization in cells and in vivo. Results: dYNH-PTX showed improved stability in mouse serum and significantly reduced tumor size in a prostate cancer xenograft model and also reduced tumor vasculature in a syngeneic orthotopic allograft mouse model of renal cancer compared with vehicle or paclitaxel treatments. Conclusion: This study reveals that targeting EphA2 with dYNH drug conjugates could represent an effective way to deliver anticancer agents to a variety of tumor types. Clin Cancer Res; 19(1); 128-37. (C) 2012 AACR.