RADT-18. PARTICLE BEAM RADIATION THERAPY PLUS TUMOR TREATING FIELDS IN THE TREATMENT OF NEWLY DIAGNOSED WHO GRADE 4 GLIOMAS: AN EARLY RESULT OF PHASE 2 SINGLE-ARM TRIAL

• Published in: Neuro-oncology (Charlottesville, Va.) Vol. 24; no. Supplement_7; pp. vii52 - vii53
• Main Authors: Qiu, Xianxin, Gao, Jing, Yang, Jing, Hu, Jiyi, Hu, Weixu, Huang, Qingting, Zhang, Haojiong, Kong, Lin, Lu, Jiade
• Format: Journal Article
• Language: English
• Published: 14.11.2022
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noac209.208

Abstract OBJECTIVES Tumor Treating Fields (TTFields) is increasingly provided to patients with WHO grade 4 gliomas following radiotherapy. Particle beam radiotherapy (PBRT) represents a novel promising radiation approach with improved therapeutic ratio. This study was aimed to report an early result of TTFields in combination with PBRT for treating WHO grade 4 gliomas based on a prospective phase 2 trial from Shanghai Proton and Heavy Ion Center. METHODS This phase 2 trial was designed as a single-arm study to test the outcome of PBRT plus TTFields. Six patients with newly diagnosed WHO grade 4 gliomas receiving surgery, PBRT, temozolomide, and TTFields, from August 2021 to May 2022, were enrolled and analyzed. Tumor histologies based on the WHO CNS5 classification system were IDH-wild glioblastoma (n=4), IDH-mutant astrocytoma (n=1), and H3G34-mutant diffuse hemispheric glioma (n=1). For PBRT, all patients were irradiated with a baseline standard dose of 60GyE/30 utilizing proton. Carbon-ion boost of 15GyE/3 for tumor residual was performed for one patient prior to proton radiation. TTFields treatment was recommended to start soon after PBRT. RESULTS With a median follow-up of 5.5 months, all patients were alive at the time of this analysis; one patient with left thalamic glioblastoma had tumor progression of distant failure outside the radiation field at 4 months after partial tumor resection. The median interval between PBRT and TTFields was 2 days (range 1-22 days). No patient had dermatitis during PBRT. No severe TTField-related skin toxicity (Grade 3 or above) was observed. Five patients (83.3%, 5/6) developed mild skin toxicities (Grade 1) during TTField treatments. CONCLUSIONS Starting TTField early following PBRT is feasible for treating WHO grade 4 gliomas, the overall side effects are mild. Prospective studies with further follow-up are warranted to identify the outcomes of PBRT in combination with TTField in terms of survival and side effects.