ID #731 The role of biopsy in treatment of children with DIPG

Abstract Diffuse Intrinsic pontine gliomas (DIPG) account 10-20% of all brain tumors in children and are one of the most common causes of death in pediatric neuro-oncology. There are no effective treatments for this disease. THE GOALS AND OBJECTIVES are to perform biopsy of DIPG, determine their histological variant and molecular genetic markers for identifying potential mutations for targeted therapy. Materials and Methods From 2021 to 2025, 32 patients were operated on at the Morozovskaya Children’s Clinical Hospital, Moscow. Patient ages ranged from 1.5 to 17 year. The duration of anamnesis varied from 1 week to 96 months (median: 1 month). Sterotactic biopsy (STB) was performed in 30 patients; open biopsy—in 2 patients. Preliminary diagnosis was made based on clinical presentation and MRI findings. Results Tumor verification was achieved in 29 patient. Morphological analysis diagnosed diffuse midline glioma in 78%. One case of ganglioglioma, one high-grade glioma, and one low-grade glioma were identified. 58% (18 samples) were analyzed by NGS. The H3K27M mutation was detected in 75%. BRAF-V600E mutations were found in two patients. FGFR2 gene mutation was identified in one patient. Based on the detected mutations, targeted therapy was prescribed. In 16% of the patients, MRI of the spinal cord revealed metastatic involvement. The overall 2-year survival for the entire group was 20%. Two-year progress-free survival (PFS) was 0%. PFS in a patient with DMG and BRAF-V600E mutation receiving targeted therapy lasted up to 21 months before tumor progression. Conclusions 1. Modern therapy for DIPG patients is ineffective. 2. Targeted therapy may become a promising approach in treating this pathology. 3. Stereotactic biopsy of diffuse brainstem tumors can be performed safely. 4. Identifying molecular targets for personalized therapy could be key to curing patients with this diagnosis.