Cyclic RGD-Functionalized closo-Dodecaborate Albumin Conjugates as Integrin Targeting Boron Carriers for Neutron Capture Therapy

• Published in: Molecular pharmaceutics Vol. 17; no. 10; pp. 3740 - 3747
• Main Authors: Kawai, Kazuki, Nishimura, Kai, Okada, Satoshi, Sato, Shinichi, Suzuki, Minoru, Takata, Takushi, Nakamura, Hiroyuki
• Format: Journal Article
• Language: English
• Published: American Chemical Society 05.10.2020
• Subjects: boron neutron capture therapy; closo-dodecaborate; cyclic RGD; integrin; tumor; albumin
• ISSN: 1543-8384; 1543-8392
• DOI: 10.1021/acs.molpharmaceut.0c00478

Cyclic RGD (cRGD) peptide-conjugated boronated albumin was developed to direct toward integrin αvβ3, which overexpresses on many cancer cells. A stepwise conjugation of c­[RGDfK­(Mal)] and maleimide-conjugated closo-dodecaborate (MID) to bovine serum albumin (BSA) afforded cRGD-MID-BSA, which was noncytotoxic toward both U87MG and A549 cells. As compared with l-BPA, selective antitumor activity of cRGD-MID-BSA toward U87MG cells overexpressing integrin αvβ3 was identified after thermal neutron irradiation. In vivo fluorescence live imaging of Cy5-conjugated cRGD-MID-BSA and MID-BSA revealed that both cRGD-MID-BSA and MID-BSA similarly reached the maximum accumulation during 8–12 h after injection. The selective accumulation and retention of Cy5-cRGD-MID-BSA was more pronounced than Cy5-MID-BSA after 24 h. An in vivo boron neutron capture therapy (BNCT) study revealed that the cRGD peptide ligand combination enhanced accumulation of MID-BSA into tumor cells in U87MG xenograft models. The significant tumor growth suppression was observed in U87MG xenograft models at a dose of 7.5 mg [10B]/kg after neutron irradiation.