Boron lipid-based liposomal boron delivery system for neutron capture therapy: recent development and future perspective

Recent development of boron cluster lipids and their liposomal boron delivery system (BDS) are summarized in this article. Boron compounds used in boron neutron capture therapy (BNCT) are, in general, nontoxic unless neutron capture reaction of boron takes place. Therefore, the boron compounds accumulated into other organs would not cause such side effects for patient. Selective and sufficient delivery of boron-10 to tumor results in the successful BNCT. There are two approaches for BDS: encapsulation of boron compounds into liposomes and incorporation of boron-conjugated lipids into the liposomal bilayer, both of which have been significantly investigated. The combination of both approaches displayed potency and, hence, the ability to reduce the total dose of liposomes without reducing the efficacy of BNCT. Boron compounds that have no affinity to tumor can potentially be delivered to tumor tissues by liposomes, therefore, liposomal BDS would be one of the most attractive approaches for efficient BNCT of various cancers.