ATRT-03. Adapted Treatment Protocol: Synchronous Atypical Teratoid/Rhabdoid CNS Tumor and Extra CNS Disease

Abstract Atypical teratoid/rhabdoid tumors (AT/RTs) of the central nervous system (CNS) are rare, aggressive, early childhood with unfavorable prognosis. There have been 31 cases reported children AT/RT CNS and extra primary tumors. In addition to its aggressive tendencies, malignant rhabdoid (MRTs) kidney also shown a common genetic abnormality-inactivating mutation SMARC B1/INI-gene. We report 22-month-old male who presented at 15 months age metastatic posterior fossa synchronous tumor left kidney. MRI brain demonstrated midline mass renal was noted incidentally on imaging spine. Pathology consistent MRT pathogenic variant found in sample, specifically SMARCB1 homozygous/biallelic deletion. Patient underwent subtotal resection subsequent radical tumor. He treated as per ACNS033 protocol 2 cycles induction high-dose methotrexate followed by vincristine, cyclophosphamide, cisplatin, etoposide complete response three tandem stem cell transplants thiotepa carboplatin for which he has tolerating responding favorably. Focal radiation therapy flank area is planned end therapy. large series AT/RTs 2017 only 3 patients were considered long-term survivors. All received combination high dose intrathecal or intravenous chemotherapy, total least one tumors, focal radiation, autologous peripheral blood transplant. case favorable our treatment. Treatment continues be challenging given tumor’s rarity mortality there no standardized protocols randomized controlled trials.