REMIND Maintenance Radiotherapy for Newly Diagnosed Glioblastoma

Glioblastoma is an aggressive primary brain tumor with high rates of local recurrence despite standard treatment with surgical resection, concurrent temozolomide and radiotherapy, and adjuvant temozolomide. This study is designed to test whether an additional single fraction of maintenance radiotherapy can be delivered safely and feasibly after standard-of-care treatment.

REMIND is a single-center investigator-initiated study enrolling adult patients with newly diagnosed glioblastoma. Eligible participants will be consented before starting standard-of-care concurrent temozolomide and radiotherapy. Following enrollment, participants will enter an observational lead-in phase while receiving their prescribed standard-of-care therapy off study. During this lead-in phase, study data collection will be limited to routine electronic medical record abstraction to confirm standard-of-care treatment administration and monitor basic clinical status.

Active study participation begins approximately 2 weeks after standard-of-care treatment, when participants undergo simulation for maintenance radiotherapy. Approximately 4 weeks after temozolomide, participants will receive maintenance radiotherapy consisting of one 2 Gy fraction delivered using intensity-modulated radiotherapy directed at the post-operative cavity and areas where previous enhancing disease was identified after surgical resection.

The primary objective is to test the safety and feasibility of delivering maintenance radiotherapy. Safety will be evaluated by monitoring toxicities and adverse events, including Grade 4 or 5 toxicities related to the experimental 2 Gy radiotherapy fraction. Feasibility will be evaluated based on treatment completion. The secondary objective is to descriptively compare the frequency of myeloid-derived suppressor cells in peripheral blood before and after maintenance radiotherapy. Participants will be followed for disease response per standard of care every 2 to 4 months until death or for up to 5 years from maintenance radiotherapy.

Inclusion criteria

• Histologically confirmed diagnosis of glioblastoma according to WHO classification criteria for which standard-of-care surgical resection, concurrent temozolomide and radiotherapy, and adjuvant temozolomide is planned
• Planning to receive standard-of-care radiotherapy with a biological effective dose of 60 Gy or less in 30 fractions
• Age 18 years or older at the time of consent
• Karnofsky performance status of 70 or higher
• Life expectancy of 3 months or longer
• Adequate organ function confirmed by laboratory values obtained within 14 days of study enrollment, defined as absolute neutrophil count at least 1.5 × 10^9/L, platelets at least 50 × 10^9/L, and hemoglobin at least 8 g/dL independent of transfusion within 14 days of screening
• Persons of childbearing potential or with partners of childbearing potential must be willing to use contraception during study treatment
• Concurrent use of other investigative treatment is permitted
• Voluntary written consent prior to the performance of any research-related activity

Exclusion criteria

• Pregnant or breastfeeding
• Presence of brain stem involvement within the planning target volume from the initial course of standard-of-care radiotherapy
• Prior radiation therapy to the brain
• Contraindication to MRI or CT
• Uncontrolled intercurrent illness, including ongoing or active infection, hypertension, serious cardiac arrhythmia requiring medication, acute cardiovascular disease or clinically manifested myocardial insufficiency, or psychiatric illness or social situations that would limit compliance with study requirements
• Any medical condition or clinical laboratory abnormality that, in the investigator's judgment, precludes safe participation in and completion of the study or could affect compliance with protocol conduct or interpretation of results