MBCL-04. 5 – AZACYTIDINE IN TREATMENT OF CHILDREN WITH DE NOVO AND RELAPSED METASTATIC MEDULLOBLASTOMA: RESULTS OF INTERCENTER PILOT STUDY

The aim of this study was to estimate treatment toxicity and event-free survival (EFS) according to therapeutic program, MYC/MYC-N gene amplification and MGMT/DNMT (1, 3a, 3b) proteins expression in tumor cells. From 2016 to 2018 twenty four patients were included in trial. Children underwent adjuvant therapy: craniospinal radiation (CSI) or local radiation therapy (RT) to the relapsed site up to 23.4Gy with 5-azacytidine, 2 cycles methotrexate/5-azacytidine/cisplatin/etoposide, 3 cycles 5-azacytidine/temozolomide - for relapsed group (arm A, n = 5); for patients with de novo medulloblastoma: arm B, n = 11 – vincristine/cyclophosphamide/cisplatin/etoposide (OPEC) - based induction, CSI 36Gy + local RT to the tumor bed up to 54Gy with 5-azacytidine, 1 cycle OPEC and 2 cycles thiophosphamide/carboplatin with auto stem cell transplantation (auto-SCT); arm C, n = 8 – cyclophosphamide/cisplatin - based induction, CSI 23.4 Gy followed by 2 cycles 5-azacytidine/thiophosphamide/carboplatin with auto-SCT, local RT with 5-azacytidine. The combination of 5-azacytidine with local RT or temozolomide was safety and tolerability. Arm C was discontinued due to severe gastrointestinal grade 3/4 toxicity, hemorrhagic syndrome after combination of 5-azacytidine with thiophosphamide/carboplatin. EFS was 0% in arm A, 53.0 ± 15.5%, 50.0 ± 17.7% in arms B and C, a median follow-up 8.8 ± 1.1 months (arm A), 18.8 ± 2.5 months (arm B), 25.0 ± 4.4 months (arm C). Addition of 5-azacytidine to RT or chemotherapy did not improve EFS of patients with MYC/MYC-N gene amplification positive tumor. There was not determined any prognostic significance of MGMT/DNMT (1, 3a, 3b) proteins expression in this cohort.