A Selective Carborane-Functionalized Gastrin-Releasing Peptide Receptor Agonist as Boron Delivery Agent for Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) allows the selective elimination of malignant tumor cells without affecting healthy tissue. Although this binary radiotherapy approach has been known for decades, BNCT failed to reach the daily clinics to date. One of the reasons is the lack of selective boron delivery agents. Using boron loaded peptide conjugates, which address G protein-coupled receptors overexpressed on tumor cells allow the intracellular accumulation of boron. The gastrin-releasing peptide receptor (GRPR) is a well-known target in cancer diagnosis and can potentially be used for BNCT. Here, we present the successful introduction of multiple bis-deoxygalactosyl-carborane building blocks to the GRPR-selective ligand [d-Phe