Etmr-27. Anti-Angiogenic Metronomic Therapy of Rare Tumours of the Central Nervous System

Abstract BACKGROUND Improvement of molecular diagnostics has led to significant changes in the categorization of paediatric brain tumours, unveiling novel tumour entities in the latest 2021 WHO classification of central nervous system (CNS) tumours (5th edition), particularly within the group of rare tumours of the CNS (encompassing rare embryonal and sarcomatous tumours (REST) and gliomas). However, treatment recommendations are currently based on small patient cohorts lacking standardized protocols, with even more limited options for progressive or relapsed disease. METHODS Patients from specialized European oncologic centres diagnosed or reclassified as REST receiving anti-angiogenic therapy after relapse (Medulloblastoma European Multitarget Metronomic Anti-Angiogenic Trial - MEMMAT) will be analysed. RESULTS So far, 14 patients from Austria, Czech Republic, Denmark and France were identified, with molecularly reclassified 4 CNS tumours with BCOR/BCORL1 alteration (CNS BCOR/BCORL1), 4 CNS astroblastomas, MN1-altered (ABMMN1), 3 embryonal tumours with multi-layered rosettes (ETMR) and 1 DICER1-mutated intracranial sarcoma (CNS DICER1) as well as 2 primitive neuroectodermal tumours (PNETs, reclassification ongoing). Initial histological classifications ranged from ependymoma group 3, ETMR, malignant peripheral nerve sheath tumour (MPNST) to EGFR-positive glioblastoma. In 2 cases categorization was unclear with either anaplastic ependymoma, plexus carcinoma or ETMR. 10 patients received standard MEMMAT protocol (biweekly intravenous Bevacizumab with oral drugs: Celebrex, Thalidomide, Fenofibrate, Cyclophosphamide/Etoposide alternating and intrathecal Etoposide and Cytarabine). In 4 cases therapy was modified with an individualized metronomic treatment regimen. CONCLUSION Therapy at initial diagnosis, duration of relapse-treatment, clinical as well as radiological response, overall survival, progression-free survival and molecular hallmarks will be presented.