ACT-02 BORON NEUTRONS CAPTURE THERAPY FOR RECURRENT HIGH-GRADE MENINGIOMAS, FROM REACTOR TO ACCELERATOR

INTRODUCTION: Recurrent high-grade meningiomas (rHGM) are difficult to control. We have applied tumor-selective particle radiation, reactor-based boron neutron capture therapy (BNCT) with excellent tumor control. METHODS: Forty-six recurrent and treatment-refractory high grade meningiomas were treated with reactor-based BNCT by Osaka Medical College (OMC) and Kyoto University Research Reactor team collaboratively until February 2019. Tumor shrinkage, overall survival (OS), progression free survival (PFS), Lesion/Normal (L/N) ratio in boronophenylalanine positron emission tomography (BPA-PET) and causes of treatment failures are analyzed. RESULTS: Subjects had been almost always treated heavily, high-risk patients for prognosis. They were received surgery 3 times and some radiotherapy 2 times averagely, prior to BNCT. All cases responded well and markedly shrunk by BNCT. The mean L/N ratio in BPA-PET was 4.0 which is higher than glioblastomas. Two-year PFS was 49.0% (95% CI: 28.84–66.49). Unfortunately follow-up was insufficient and 2 year OS was very similar to 2 year PFS. Treatment failures were observed as recurrence out of fields of neutron irradiation, systemic metastasis and in field local recurrence almost equally. SUMMARY AND PROSPECTS: Median PFS and OS of rHGM are 5 months and 2 years respectively in literatures. We achieved relatively favorable results by reactor-based BNCT. On the other hand, we performed accelerator-based BNCT clinical trial for recurrent glioblastomas steadily first in the world. Based on these backgrounds, we applied investigator-lead, clinical trial of accelerator-based BNCT for rHGM as RCT design. Government (PMDA and AMED) has approved our proposal. We start this trial with the primary endpoint as PFS, from August 2019. Treatment arm is BNCT and control one is best-supportive care. If the subjects in control arm show progress disease in follow-up, they can be treated by BNCT as rescue treatments. We will introduce details of this trial in our presentation.