First clinical results on the Finnish study on BPA-mediated BNCT in glioblastoma

An open phase I dose-escalation boron neutron capture therapy (BNCT) study on glioblastoma multiforme (GBM) was initiated at the FiR 1 BNCT facility, Espoo, Finland, in May 1999. The aim of the study is to investigate the safety of boronophenylalanine (BPA)-mediated BNCT. Ten GBM patients were treated with a 2-field treatment plan using one fraction. BPA-F was used as the 10B carrier infused as a fructose solution 290 mg BPA/kg over 2-hours prior to irradiation with epithermal neutrons. Average doses to the normal brain, contrast enhancing tumor, and the target volume ranged from 3.0 to 5.6 Gy (W), from 35.1 to 66.7 Gy (W), and from 29.6 to 53.6 Gy (W), respectively. BNCT was associated with acceptable toxicity. The median follow-up is 9 months (range, 3 to 16 months) post diagnosis in July 2000. Seven of the 10 patients have recurrent or persistent GBM, and the median time to progression is 8 months. Only one patient has died, and the estimated 1-year overall survival is 86%. Five of the recurrent tumors were treated with external beam photon radiation therapy to the total dose of 30-40 Gy with few acute side-effects. These preliminary findings suggest that acute toxicity of BPA-mediated BNCT is acceptable when average brain doses of 5.6 Gy (W) or less are used. The follow-up time is too short to evaluate survival, but the estimated 1-year survival of 86% achieved with BNCT followed by conventional photon irradiation at the time of tumor progression is encouraging and emphasizes the need of further investigation of BPA-mediated BNCT.