ATRT-09. Atypical teratoid/rhabdoid tumor: Can it become a chronic active disease?

Abstract Atypical teratoid/rhabdoid tumor (ATRT) is a rare and aggressive pediatric brain tumor with poor long-term survival. We present the case of an 8-year-old girl who has survived seven years since her ATRT diagnosis at 12 months of age. She initially presented with progressive ataxia and obstructive hydrocephalus, necessitating gross total resection of a posterior fossa tumor in January 2018. Histopathology confirmed ATRT with a somatic, non-germline SMARCB1 mutation. Post-surgery, she underwent the Dana-Farber ATRT regimen with focal proton radiation, achieving remission. Recurrence with spinal cord lesions and leptomeningeal disease was noted eight months later and managed with Ommaya reservoir placement, intrathecal Topotecan, Etoposide, Thiotepa, and a metronomic antiangiogenesis regimen. Compassionate use of Alisertib was initiated but halted due to pancytopenia. Subsequent bone marrow analysis revealed myelodysplastic syndrome with an 11q23 alteration, treated with 5-azacytidine and prolonged Alisertib, leading to resolution of the cytogenetic anomaly. Thoracic spine radiation and Omburtamab monoclonal antibody therapy were administered; however, metastatic disease in the right Sylvian fissure developed and was treated with whole-brain radiation and additional Alisertib. Further metastatic disease in the brain was addressed with stereotactic radiosurgery, followed by sequential interventions including gemcitabine-bevacizumab, oral metronomic therapy with thalidomide, celecoxib, fenofibrate, sirolimus, and Tazemetostat. Gamma knife radiation and focused spinal radiation were also utilized for progressive lesions. DFMO and Paxalisib were attempted but discontinued due to toxicity. Spinal radiation and a prolonged course of biweekly intraventricular chemotherapy with alternating Topotecan and Thiotepa were well-tolerated without significant side effects. This case underscores the integration of advanced therapies, personalized medicine, and multidisciplinary care in achieving long-term survival in ATRT. Over seven years of survival with an adequate quality of life highlights significant progress in treating this aggressive malignancy, offering hope for improved outcomes in high-risk pediatric tumors.