Second-Line Metronomic Maintenance for Relapsed Posterior Fossa ATRT: A Case from Iran

Atypical teratoid/rhabdoid tumor (ATRT) is a rare, aggressive embryonal brain tumor of early childhood with poor outcomes after relapse, especially where high-dose chemotherapy and stem cell transplantation are inaccessible. We report a 6-month-old boy in Iran with posterior fossa ATRT treated with gross total resection, focal radiotherapy, and standard chemotherapy, who relapsed locally. Second resection followed by salvage chemotherapy (temozolomide, irinotecan, vincristine, bevacizumab) achieved complete radiological response; his parents then declined high-dose chemotherapy with autologous stem cell transplant. We therefore initiated a 2-year metronomic maintenance regimen (oral temozolomide, bevacizumab, intrathecal cytarabine/dexamethasone, and celecoxib), which was well tolerated, with no grade 3 to 4 toxicity and normal growth and development. He remains in complete remission 2 years after completing therapy. This case supports metronomic maintenance as a durable, low-cost, oral option for relapsed ATRT when standard salvage is refused or unavailable, particularly in low- and middle-income countries with limited transplant access, and underscores the need for systematic study of metronomic strategies in ATRT and other relapsed embryonal brain tumors.