Study protocol: PreOperative Brain Irradiation in Glioblastoma (POBIG)-A phase I trial

Background: Glioblastoma is a high-grade aggressive neoplasm whose outcomes have not changed in decades. In the current treatment pathway, tumour growth continues and remains untreated for several weeks post -diagnosis. Intensified upfront therapy could target otherwise untreated tumour cells and improve the treat-ment outcome. POBIG will evaluate the safety and feasibility of single-fraction preoperative radiotherapy for newly diagnosed glioblastoma, assessed by the maximum tolerated dose (MTD) and maximum tolerated irra-diation volume (MTIV).Methods: POBIG is an open-label, dual-centre phase I dose and volume escalation trial that has received ethical approval. Patients with a new radiological diagnosis of glioblastoma will be screened for eligibility. This is deemed sufficient due to the high accuracy of imaging and to avoid treatment delay. Eligible patients will receive a single fraction of preoperative radiotherapy ranging from 6 to 14 Gy followed by their standard of care treatment comprising maximal safe resection and postoperative chemoradiotherapy (60 Gy/30 fr) with con-current and adjuvant temozolomide). Preoperative radiotherapy will be directed to the part of the tumour that is highest risk for remaining as postoperative residual disease (hot spot). Part of the tumour will remain unirra-diated (cold spot) and sampled separately for diagnostic purposes. Dose/volume escalation will be guided by a Continual Reassessment Method (CRM) model. Translational opportunities will be afforded through comparison of irradiated and unirradiated primary glioblastoma tissue.Discussion: POBIG will help establish the role of radiotherapy in preoperative modalities for glioblastoma. Trial registration: NCT03582514 (clinicaltrials.gov).

Automated summary

The POBIG trial aims to evaluate the safety and feasibility of single-fraction preoperative radiotherapy for newly diagnosed glioblastoma by assessing the maximum tolerated dose and maximum tolerated irradiation volume. The study includes delivering radiation ranging from 6 to 14 Gy in combination with standard care treatment. The objective is to establish the role of radiotherapy in preoperative modalities for glioblastoma.