ZD2 peptide

ZD2 peptide is a polypeptide capable of binding EDB-FN, with a Kd value of 3.45 μM. It specifically targets the EDB protein segment of extradomain B fibronectin, which serves as a biomarker for the tumor microenvironment. Additionally, ZD2 peptide can be conjugated with imaging agents and is applicable in cancer research.

The cyclic ZD2 peptide exhibits moderate binding affinity to the EDB-FN protein fragment with a Kd of 11 μM measured by surface plasmon resonance. In contrast, the Linear ZD2 peptide conjugated with Gd (HP-DO3A) shows higher affinity, with a Kd of 1.7 μM determined through the same method. ZD2-N3-Gd (HP-DO3A) (MT218), another linear ZD2 peptide conjugated with Gd (HP-DO3A), displays a moderate binding affinity to the EDB-FN protein fragment with a Kd of 3.45 μM as measured by surface plasmon resonance. The ability of the cyclic ZD2 peptide to specifically bind to EDB-FN in invasive human prostate cancer sections has been validated through competitive blockade experiments with anti-EDB-FN monoclonal antibody.

ZD2−N3-Gd(HP-DO3A) administered intravenously at a single dose of 0.02-0.04 mmol/kg induces a dose-dependent enhancement in MRI signals in rat PC3 prostate cancer xenograft tumors. Specifically, at 0.02 mmol/kg, the CNR increases threefold, while at 0.04 mmol/kg, the CNR rises sixfold. No significant enhancement is observed in EDB-FN low tumors.