RTID-01. ACCELERATOR-BASED BORON NEUTRON CAPTURE THERAPY, RANDOMIZED CONTROLLED TRIAL FOR RECURRENT AND REFRACTORY HIGH-GRADE MENINGIOMAS

Abstract INTRODUCTION High-grade meningiomas (HGMs) recurred after X-ray treatment showed pessimistic prognosis. We started “A phase II investigator-lead RCT using accelerator-based BNCT system for refractory recurrent high-grade meningioma”. MATERIALS AND METHODS We prepared 2 study arms, BNCT test treatment arm (12 subjects) and control best supportive care arm (6 subjects) in randomized controlled trial (RCT) fashion. PFS judged by the third-party committee was primary endpoint and PFS judged by investigators themselves and OS of BNCT arm were secondary endpoints. Rescue BNCT was permitted for control group patients, if they showed progress disease (PD). RESULTS Three and two grade 3 subjects were included in BNCT and control arm, respectively. Others were grade 2 subjects. As of March 31, 2024, 10 out of 12 in BNCT arm and all 6 cases in control arm were judged as PD. mPFS judged by investigators showed 65 and 8 weeks for BNCT and control arm, respectively (P=0.0002, Wilcoxon). Six out of 12 in BNCT and 4 out of 6 cases in the control arm were dead. OS-2 year rates of BNCT and control arms are 91.7% and 33.3%, respectively (p=0.045, Wilcoxon). Five out of 6 cases in control arm received rescue BNCT after PD assessments. With regard to best response on MRI, PR, SD were 5 and 7 cases in treatment arms (ORR was 41.7%). CONCLUSION mPFS judged by third party committee is still being closed and unknown, so far. With regard to secondary endpoints, there are marked differences in both arms in mPFS judged by investigators. Recently, the results of RCT of “Trabectedine” organized by EORTC was reported. Unfortunately there was no effect of Trabectedine not only in PFS but in OS. In our current RCT results BNCT arm is extremely excellent in comparison with EORTC RCT of “Trabectedine” both in OS and PFS.