ETMR-15. USE OF HIGH-DOSE CHEMOTHERAPY FOR TWO CHILDREN WITH EMBRYONAL TUMOR WITH MULTILAYERED ROSETTES

Embryonal tumor with multilayered rosettes (ETMR) is new entity defined in the 4(th) revised edition of the WHO classification of tumors of the central nervous system. Although radical resection, radiotherapy, and multiagent chemotherapy are considered to be necessary for ETMR, the efficacy of chemotherapy for ETMR in Japan has not been established. Here, we report different clinical courses for two children with localized ETMR treated with the St. Jude medulloblastoma-96 (SJMB96) regimen, which consists of four cycles of high-dose chemotherapy with autologous peripheral blood stem cell transplantation. For both children, the diagnosis of ETMR, C19MC-altered was confirmed after gross total tumor resection. Multiagent chemotherapy was administered following cranio-spinal irradiation with local boost. One month after completion of the treatment, one patient experienced local recurrence but has been in remission for over 2 years after tumor resection and stereotactic irradiation with a CyberKnife and treatment every three weeks with bevacizumab. The other patient also experienced local recurrence after the third cycle of chemotherapy and several times thereafter. Although she again underwent tumor resection and local irradiation, her tumor grew larger and invaded. Because her prognosis was very poor, her parents choose only palliative care. Based on our experience, we believe that continuous chemotherapy at conventional doses is preferred over intensive-dose chemotherapy such as SJMB96. However, the number of reports on chemotherapy for ETMR is still small, and a prospective multicenter trial is needed to establish effective chemotherapy for ETMR.