Arsenic Trioxide Combined With Chemotherapy for Relapsed SHH-Activated and/or TP53-Mutant Medulloblastoma

This prospective, open-label, single-arm, multicenter study will evaluate the efficacy and safety of arsenic trioxide (ATO) combined with chemotherapy in pediatric patients with relapsed or refractory SHH-activated medulloblastoma and/or TP53-mutant medulloblastoma. Eligible participants will be 18 months to 18 years of age. Participants will receive six cycles of induction chemotherapy containing ATO in combination with etoposide and either cisplatin or cyclophosphamide. The primary outcome is the objective response rate (ORR), defined as the proportion of participants achieving a complete response or partial response, assessed according to the Response Assessment in Pediatric Neuro-Oncology (RAPNO) criteria by an independent review committee. Secondary outcomes include overall survival, progression-free survival, and treatment-related safety, including adverse events and serious adverse events. A total of 78 participants are planned for enrollment.