MB-51: TANDEM HEMATOPOIETIC STEM CELL TRANSPLANT USING SYNGENEIC CELLS

INTRODUCTION: Survival of central nervous system (CNS) embryonal tumors in infants remains dismal with better outcome being achieved with hematopoietic stem cell transplant (HSCT) consolidation. Tandem HSCT has been studied as a low toxicity alternative with promising survival rates; however it requires larger hematopoietic stem-cell harvesting. OBJECTIVE: To describe a patient submitted to three sequential tandem HSCT, receiving autologous stem cells rescue for the first two procedures and syngeneic for the third. METHODS: Case report with medical records review. RESULTS: Female, 3.9 years old, R0M0 desmoplastic medulloblastoma submitted to modifying HIT-SKK protocol. Relapse occurred at primary site two months after the end of treatment. The patient underwent second surgery followed by tandem HSCT. Peripheral stem-cell harvesting was performed after cisplatin/etoposide chemotherapy, but a low dose cell count was obtained (6,4x10[6] CD34+ cells/kg). To avoid treatment delay for the 3rd transplant, marrow stem-cells were harvested from an identical twin sister. Conditioning treatment was performed according COG99703 protocol (Carboplatin 17mg/kg/day and Thiotepa 6.5mg/kg/day 2 days). The period between 1st and 2nd HSCT was 25 days and 20 days between 2nd and 3rd. Engraftment occurred at D + 10 on the 1st and 2nd HSCT and D + 9 in the 3rd HSCT. Number of infused CD34+ cells for 1st HSCT was 2.53x10(6)/kg, for 2nd 3,08x10(6)/kg and for 3rd (syngeneic cells) 10,3x10(6)/kg. The patient is now three months after HSCT and craniospinal radiotherapy (24Gy). CONCLUSION: Syngeneic transplant seem to be a reasonable strategy for patients unable to harvest enough progenitor cells.