RADT-46. FIRST STRIKE: PHASE 1 TRIAL OF NEOADJUVANT RADIOTHERAPY IN NEWLY DIAGNOSED HIGH GRADE GLIOMAS

Abstract BACKGROUND Neoadjuvant radiotherapy (NART) in high-grade gliomas (HGG) may improve treatment efficacy by exploiting better oxygenation for enhanced radiosensitivity, allowing better tumor delineation before anatomical distortion by surgery, and enabling earlier initiation of therapy during often lengthy surgical wait times. It may also reduce tumor burden to facilitate surgical ease and help achieve favorable pathological responses. AIM To test the safety and feasibility of NART in newly diagnosed HGG. METHODOLOGY A sample size of 10 patients was determined for this pilot MD thesis study. Patients were selected based on radiological evaluation of Multiparametric CEMRI Brain by multidisciplinary tumor board comprising Radiotherapist, Neuro-radiologist, and Neurosurgeon. Patients then received NART to primary lesion with 45 Grays in 15 fractions over 3 weeks, with concurrent Temozolomide (TMZ) at 75mg/m2. After 4-6 weeks patients underwent Maximum Safe Resection. Following this, after an interval of 4 weeks, patients were started on Adjuvant Temozolomide at 150-200 mg/m2 for 6-12 months. The primary end-point of the study is to assess Safety and Feasibility of NART in HGG. Surgical ease post NART, Quality of Life (QoL), Overall treatment time, Radiation Dosimetry, and Progression-free and Overall Survival are the secondary end-points. Patients are periodically followed up clinically, radiologically, and for QoL assessment with EORTC QLQ-C30 and BN-20. Neurosurgeon(s) are interviewed post-surgery to assess ease of surgery based on self-designed questionnaire. RESULTS This is an ongoing study#. Out of 10, five patients have completed NART. All five patients tolerated the NART without any complications. Two out of these patients, suffered RTOG grade 2 CNS toxicity and required Dexamethasone cover on outpatient basis, during radiation therapy. None of the patients deteriorated during treatment. Three patients have undergone surgery and started adjuvant TMZ. Interim data, although premature, demonstrate encouraging results # Oct’2025, all 10 patients will have undergone NART.