A Phase I/II clinical trial of
boron neutron capture therapy (BNCT) for
glioblastoma multiforme is underway using the
amino acid analog
p-boronophenylalanine (BPA) and the epithermal neutron beam at the Brook-haven Medical Research Reactor. Biodistribution studies were carried out in 18 patients at the time of
craniotomy using an i.v. infusion of BPA, solubilized as a
fructose complex (
BPA-F). There were no toxic effects related to the
BPA-F administration at doses of 130, 170, 210, or 250 mg BPA/kg
body weight. The
tumor/ blood, brain/blood and scalp/blood
boron concentration ratios were approximately 3.5:1, 1:1 and 1.5:1, respectively. Ten patients have received BNCT following 2-hr infusions of 250 mg BPA/kg
body weight. The average
boron concentration in the blood during the irradiation was 13.0 +/- 1.5 micrograms 10B/g. The prescribed maximum dose to normal brain (1 cm3 volume) was 10.5 photon-equivalent Gy (Gy-Eq). Estimated maximum and minimum doses (mean +/- sd, n = 10) to the
tumor volume were 52.6 +/- 4.9 Gy-Eq (range: 64.4-47.6) and 25.2 +/- 4.2 Gy-Eq (range: 32.3-20.0), respectively). The estimated minimum dose to the target volume (
tumor +2 cm margin) was 12.3 +/- 2.7 Gy-Eq (range: 16.2-7.8). There were no adverse effects on normal brain. The scalp showed mild
erythema, followed by
epilation in the 8 cm diameter field. Four patients developed recurrent
tumor, apparently in the lower dose (deeper) regions of the target volume, at post-BNCT intervals of 7,5,3.5 and 3 months, respectively. The remaining patients have had less than 4 months of post-BNCT follow-up. BNCT, at this starting dose level, appears safe. Plans are underway to begin the dose escalation phase of this protocol.