Boron Neutron Capture Therapy (BNCT) as Treatment of Glioblastoma

Overview

Boron Neutron Capture Therapy (BNCT) is an experimental radiation therapy technique that is based on the principle of irradiating boron atoms with neutrons. When neutrons have relatively low energy, boron atoms that have been targeted to cancerous tissue using a suitable boron carrier (an amino acid derivative called BPA, boronophenylalanine) will capture the neutrons. As a result from the neutron capture the boron atoms will split into two, producing helium and lithium ions. The helium and lithium ions, in turn, have only a short pathlength in tissue (about 5 micrometers) and will deposit their cell damaging effect mainly within the tumor provided that the boron carrier (BPA) has accumulated in the tumor. In practice, the study participants will receive BPA as an approximately 2-hour intravenous infusion, following which the tumor is irradiated with low energy (epithermal) neutrons obtained from a nuclear reactor at the BNCT facility. BNCT requires careful radiation dose planning, but neutron irradiation will last approximately only for one hour. In this study BNCT is given only once. The study hypothesis is that glioblastoma tissue may accumulate the boron carrier compound, and glioblastoma might respond to BNCT.

This is a single BNCT-facility, non-randomized, non-comparative, prospective, open-label, phase I/II trial to determine the value of BNCT in the treatment of subjects who have undergone surgery for glioblastoma, but glioblastoma has not been treated with radiation therapy or chemotherapy. The neutron irradiation site is the FiR 1 reactor site, located at Otaniemi, Espoo, Finland, about 6 kilometers from the Helsinki University Central Hospital, Helsinki, where patient evaluation and post-irradiation care will take place. BPA is infused as a fructose complex (BPA-F) into a peripheral vein over 2 hours prior to neutron irradiation. Blood samples will be taken before starting the BPA infusion, and thereafter at 20 to 40 minute intervals during the infusion, following infusion, and after delivering neutron irradiation to monitor the blood boron concentration. The blood samples will be analyzed for boron to estimate the average blood boron level during neutron irradiation. The first 12 patients are treated using a BPA dose of 290 mg/kg, following which the dose of BPA is increased stepwise to 500 mg/kg, provided that unacceptable toxicity will not occur. All patients will be evaluated for response using CT or magnetic resonance imaging (MRI).