Biodistribution of sodium borocaptate (BSH) for boron neutron capture therapy (BNCT) in an oral cancer model Marcela A. GarabalinoElisa M. HeberAndrea Monti HughesSara J. Gonzalez • Ana J. MolinariEmiliano C. C. PozziSusana NievasMaria E. ItoizRomina F. Aromando • David W. NiggWilliam BauerVeronica A. TrivillinAmanda E. Schwint

Boron neutron capture therapy (BNCT) is based on selective accumulation of 10 B carriers in tumor followed by neutron irradiation. We previously proved the therapeutic success of BNCT mediated by the boron compounds boronophenylalanine and sodium decahyd- rodecaborate (GB-10) in the hamster cheek pouch oral cancer model. Based on the clinical relevance of the boron carrier sodium borocaptate (BSH) and the knowledge that the most effective way to optimize BNCT is to improve tumor boron targeting, the specific aim of this study was to perform biodistribution studies of BSH in the hamster cheek pouch oral cancer model and evaluate the feasibility of BNCT mediated by BSH at nuclear reactor RA-3. The general aim of these studies is to contribute to the knowl- edge of BNCT radiobiology and optimize BNCT for head and neck cancer. Sodium borocaptate (50 mg 10 B/kg) was administered to tumor-bearing hamsters. Groups of 3-5 animals were killed humanely at nine time-points, 3-12 h post-administration. Samples of blood, tumor, precancer- ous pouch tissue, normal pouch tissue and other clinically relevant normal tissues were processed for boron mea- surement by optic emission spectroscopy. Tumor boron concentration peaked to therapeutically useful boron con- centration values of 24-35 ppm. The boron concentration ratio tumor/normal pouch tissue ranged from 1.1 to 1.8. Pharmacokinetic curves showed that the optimum interval between BSH administration and neutron irradiation was 7-11 h. It is concluded that BNCT mediated by BSH at nuclear reactor RA-3 would be feasible.