Boron neutron capture therapy for cancer. Realities and prospects

Abstract

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when a stable isotope, boron‐10 (10B), is irradiated with low‐energy thermal neutrons (nth) to yield (4He) α‐particles and 7Li nuclei (10B + nth→ [11B] → 4He + 7Li + 2.31 MeV). The success of BNCT as a tumoricidal modality is dependent on the delivery of a sufficient quantity of 10B and nth to individual cancer cells to sustain a lethal 10B(n, α) 7Li reaction. The current review covered the radiobiologic considerations on which BNCT is based, including a brief discussion of microdosimetry and normal tissue tolerance. The development of tumor‐localizing boron compounds was discussed, including the sulfhydryl‐containing polyhedral borane, sodium borocaptate (Na2 B12 H11 SH), and borono‐phenylalanine [BPA], both of which are currently being used clinically in Japan as capture agents for malignant brain tumors and melanomas, respectively. Compounds currently under evaluation, such as boronated porphy‐rins, nucleosides, liposomes, and monoclonal antibodies (MoAbs), were also considered. Nuclear reactors have been used as the exclusive source of neutrons for BNCT. The use of low‐energy (0.025 eV) thermal neutrons and higher‐energy 1–10, 000 eV) epithermal beams, beam optimization, and possible alternative neutron sources (accelerators) were also discussed. Clinical studies performed in the United States during the 1950s and 1960s for the treatment of malignant brain tumors were reviewed. Current studies in Japan and future studies in Europe and the United States concerning the treatment of glioblastomas and melanomas by BNCT were discussed, as were critical issues that must be addressed if BNCT is ever to be a useful therapeutic modality.

Mechanistic Insights into the Suppression of Drug Resistance by Human Immunodeficiency Virus Type 1 Reverse Transcriptase Using α-Boranophosphate Nucleoside Analogs

“…Such oligonucleotides are resistant to exonucleases and may find applications in direct PCR product sequencing (8 -11). Oligonucleotides bearing a borano (BH 3 ) group on the intermediate linkage have also been used in various applications such as boron neutron capture therapy for cancer treatments or antisense technologies (10,12). Boronated nucleotides were also described to display antineoplastic and hypolipidemic activities (13,14).…”

The Effects of Boron Neutron Capture Therapy on Liver Tumors and Normal Hepatocytes in Mice

“…We examined the effects of BNCT on experimental liver tumors and normal hepatocytes by using two boron compounds which are being used in clinical BNCT trials for malignant glioma and malignant melanoma, [3][4][5] to explore the feasibility of BNCT treatment of liver tumors. was prepared as follows.…”

Utilisation du détecteur solide de traces CR39 à la détermination du10B. Intérêt possible à la boroneutrothérapie

“…La boroneutrothérapie (BNT) est un traitement du cancer qui consiste à incorporer un produit boré dans la tumeur et à l'exposer ensuite aux neutrons (Barth et al, 1992;Dewit et al, 1990). La BNT est fondée sur les réactions nucléaires induites par les neutrons thermiques sur ' OB, isotope du bore à 19,s % d'abondance A. SEGHOüR, J.-C. SENS naturelle.…”

“…Il s'agit des facteurs de fixation et de sélectivité représentés respectivement par la concentration minimale de bore fixée par cellule, estimée à i09 atomeskellule qui assure l'effet létal, et du rapport de la concentration du bore dans la cellule à celle qui peut exister dans le sang et qui assure l'irradiation des cellules cancéreuses seules (Barth et al, 1992;Dewit et al, 1990). La détermination de la cinétique sur cultures de la concentration du bore dans les cellules peut être effectuée par la détection du rayonnement gamma prompt de la réaction 'OB(n, a) 7Li* émis par le noyau excité 7Li* à une énergie de 478 keV (Kobayashi et Kanda, 1983), par spectrométrie d'emission atomique (Barth et al, 1991) ou à l'aide des détecteurs solides de traces nucléaires LRl15 ou CN85 (Duval et al, 1980;Martini et al, 1985;Takagaki et Mishima, 1990).…”