A Phospholipid-PEG2000 Conjugate of a Vascular Endothelial Growth Factor Receptor 2 (VEGFR2)-Targeting Heterodimer Peptide for Contrast-Enhanced Ultrasound Imaging of Angiogenesis

The transition Of a targeted ultrasound contrast agent front animal imaging to testing ill clinical studies requires considerable Chemical development. The nature of the Construct changes from an agent that is chemically attached to microbubbles to one where the targeting group is Coupled to a phospholipid, for direct incorporation to the bubble surface. We provide in efficient Method to attach it heterodimeric peptide to it pegylated phospholipid and show that the resulting Construct retains nanomolar affinity for its target. vascular endothelial growth factor receptor, 2 (VEGFR2), for both the human (kinase insert domain-containing receptor - KDR) and the mouse (fetal liver kinase I - Flk-1) receptors. The purified phospholipid-PFG-peptide isolated from TFA-based eluents is not stable with respect to hydrolysis of the fatty ester moieties. This leads to the time-dependent formation of the lysophospholipid and the phosphoglycerylamide derived front the degradation of the product. Purification of [lie product using neutral eluent Systems provides a stable product. Methods to prepare the lysophospholipid (hydrolysis product) are also included. Biacore binding data demonstrated the retention Of binding, of the lipopeptide to the KDR receptor. The phospholipid-PEG2000-peptide is smoothly incorporated into gas-filled microbubbles and provides imaging of angiogenesis in it rat tumor model.