Folate-appended cyclodextrin improves the intratumoral accumulation of existing boron compounds

A Critical Review of Radiation Therapy: From Particle Beam Therapy (Proton, Carbon, and BNCT) to Beyond

In this paper, we discuss the role of particle therapy—a novel radiation therapy (RT) that has shown rapid progress and widespread use in recent years—in multidisciplinary treatment. Three types of particle therapies are currently used for cancer treatment: proton beam therapy (PBT), carbon-ion beam therapy (CIBT), and boron neutron capture therapy (BNCT). PBT and CIBT have been reported to have excellent therapeutic results owing to the physical characteristics of their Bragg peaks. Variable drug therapies, such as chemotherapy, hormone therapy, and immunotherapy, are combined in various treatment strategies, and treatment effects have been improved. BNCT has a high dose concentration for cancer in terms of nuclear reactions with boron. BNCT is a next-generation RT that can achieve cancer cell-selective therapeutic effects, and its effectiveness strongly depends on the selective ¹⁰B accumulation in cancer cells by concomitant boron preparation. Therefore, drug delivery research, including nanoparticles, is highly desirable. In this review, we introduce both clinical and basic aspects of particle beam therapy from the perspective of multidisciplinary treatment, which is expected to expand further in the future.

Fructose-functionalized polymers to enhance therapeutic potential of p-boronophenylalanine for neutron capture therapy

In boron neutron capture therapy (BNCT), boron drugs should accumulate selectively within a tumor and be quickly cleared from blood and normal organs. However, it is usually challenging to achieve the efficient tumor accumulation and the quick clearance simultaneously. Here we report the complex composed of a fructose-modified poly(ethylene glycol)-poly(l-lysine) block copolymer and p-boronophenylalanine, termed PEG-P[Lys/Lys(fructose)]-BPA, as a boron delivery system permitting selective accumulation within the target tumor with quick clearance from normal organs as well as blood. Our PEG-P[Lys/Lys(fructose)]-BPA could be internalized into tumor cells through LAT1 amino acid transporter-mediated endocytosis and retain in the targeted cells, thereby accomplishing more efficient accumulation and retention in a subcutaneous tumor than clinically used fructose-BPA complexes. Importantly, the moderately cationic property of the polymer facilitated renal clearance and PEG-P[Lys/Lys(fructose)]-BPA exhibited high accumulation contrast between the target tumor and the blood/normal organ. Finally, upon thermal neutron irradiation, PEG-P[Lys/Lys(fructose)]-BPA significantly inhibited the tumor growth in mice. PEG-P[Lys/Lys(fructose)]-BPA may be a promising boron delivery system for BNCT.