The Development of Boron Analysis and Imaging in Boron Neutron Capture Therapy (BNCT)

Abstract

Boron neutron capture therapy (BNCT) is a selective biological targeted nuclide technique for cancer therapy. It has the following attractive features: good targeting, high effectiveness, and causes slight damage to surrounding healthy tissue compared with other traditional methods. It has been considered as one of the promising methods for the treatment of various cancers. Measuring 10B concentrations is vital for BNCT. However, the existing technology and equipment cannot satisfy the real-time and accurate measurement requirements, and more efficient methods are in demand. The development of methods and imaging applied in BNCT to help measure boron concentration is described in this review.

Polyglycerol Functionalized 10B Enriched Boron Carbide Nanoparticle as an Effective Bimodal Anticancer Nanosensitizer for Boron Neutron Capture and Photothermal Therapies

“…After the 10 B 4 C‐PG injection from the tail vein of the mice we implanted CT26 cells subcutaneously, 10 B concentrations of major organs, blood and tumor were determined by ex vivo analysis using the prompt γ‐ray microanalysis (PGRA) system. [ 5,43 ]…”

“…After the 10 B 4 C-PG injection from the tail vein of the mice we implanted CT26 cells subcutaneously, 10 B concentrations of major organs, blood and tumor were determined by ex vivo analysis using the prompt γ-ray microanalysis (PGRA) system. [5,43] The time course of the biodistribution (Figure 2a) shows that 10 B concentrations in spleen, liver, and blood are much higher than those in kidney and tumor at the early stage. While 10 B concentration in blood (B) decreases continuously with the halflife of 7.3 h (Figure 2b), those in spleen and liver are kept to be relatively high for 48 h. In spite of the trap by liver and spleen, enough amount of 10 B 4 C-PG still circulates in the blood to accumulate in the tumor.…”

“…Under such circumstances, growing numbers of reviews about BNCT has been published for the last few years, reflecting the increasing expectations. [1][2][3][4][5][6][7][8][9][10][11][12] In view of clinical applications, most of the reviews claim the need for novel 10 B carriers to meet the following requirements; 1) low intrinsic toxicity, 2) high boron accumulation in tumor ( 10 B/tumor tissue (wt/wt) ≥ 20 ppm), and 3) rapid clearance from blood and long persistence in tumor ( 10 B concentration ratio in tumor/blood (T/B ratio) ≥ 3). In light of low tumor specificity and retentivity of the two clinically used drugs, sodium borocaptate (BSH) and boronophenylalanine (BPA), [8] the 10 B carriers have been designed toward a nanometer size by conjugating boron agents with (bio)polymers and relatively large molecules, [13][14][15] encapsulating boron agents in micelles, [16,17] and incorporating boron atoms in nanoparticles (NPs).…”

Design, Synthesis, and Biological Applications of Boron-Containing Polyamine and Sugar Derivatives

“…It is well established that macrocyclic polyamine ligands such as 1,4,7-triazacyclononane ( [9]aneN 3 ) 1, 1,4,7,10-tetraazacyclododecane ( [12]aneN 4 , cyclen) 2, and 1,4,7,10,13-pentaazacyclopentadecane ([15]aneN 5 ) 3 are able to form more stable complexes 4-6 with metal ions such as Cu 2+ , Ni 2+ , and Zn 2+ in aqueous solution (Figure 1) than metal complexes of linear polyamine types [16,17]. In addition, metal ions in these complexes, especially the Zn 2+ ion in Zn 2+ -cyclen complex (5), possess strong Lewis acidity and the deprotonated Zn 2+ -bound H 2 O (HO − ) functions as a nucleophile and a base in aqueous solution at neutral pH [18][19][20][21][22][23].…”

“…The selective and efficient accumulation of boron into tumor tissues is one of the important clues for successful BNCT and, as described below, two boron compounds have been approved for use as BNCT drugs. In addition, monitoring the distribution of boron in patients is required for planning treatment protocols to determine the irradiation doses and positions of the patient [9].…”