ENHANCED BORON UPTAKE IN RG-2 RAT GLIOMAS BY ELECTROPERMEABILIZATION IN-VIVO - A NEW POSSIBILITY IN BORON NEUTRON-CAPTURE THERAPY

Accumulation of boron in tumor tissue is an indispensable requirement for boron neutron capture therapy and it is important that the uptake is as high as possible. In this work we have studied the influence of electropermeabilization in vivo on the uptake of boron in normal and R G 2 glioma bearing Fischer 344 rats. Two different boron compounds, a sulfhydryl boron hydride (BSH) and a boronated porphyrin (BOPP), have been investigated. The rats were infused intravenously during 5 min wi th 175 mug BSH/g body weight or 12 mug BOPP/g body weight. Two electro des were placed 5 mm apart in the brain and electropermeabilization wa s performed with eight square 400 V pulses at 4 and 7 min after the en d of the infusion. After 6 h the animals were killed, and the boron co ntent in the tumors and the surrounding brain was measured with neutro n-activated autoradiography. In electropermeabilized healthy animals t he BOPP uptake was low and limited to the electrode lessons, whereas B SH was spread extensively throughout the hemisphere. Rats with gliomas showed doubled (BOPP) to 10-fold (BSH) uptake of boron in the tumor w hen electropermeabilization was performed as compared with untreated a nimals. We conclude that electropermeabilization in the future may pro vide an interesting possibility to increase the uptake of certain boro n compounds before neutron capture therapy.