• Daisuke Tomizawa, Katsuyoshi Koh, Masahiro Hirayama, Takako Miyamura, Michiki Hatanaka, Yutaka Saikawa, and Eiichi Ishii.
• Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan. dtomizawa.ped@tmd.ac.jp
• Pediatr Blood Cancer. 2009 Jul 1; 52 (7): 808-13.

BackgroundDespite the poor outcome of recurrent or refractory acute lymphoblastic leukemia (ALL) in infants with MLL gene rearrangement, few studies have focused on this specific group. We conducted a retrospective analysis of infants with recurrent or refractory ALL from two previous consecutive Japanese studies to clarify the characteristics and prognostic factors among these patientsProcedureAll recurrent or refractory ALL infants with MLL gene rearrangement (MLL-R) who were registered in two consecutive Japanese nation-wide multicentric trials (MLL96 and MLL98; between 1995 and 2001) were eligible for the study.ResultsAmong 80 MLL-R ALL infants, 34 cases of recurrence and 5 induction failures occurred. The median duration of first remission was 5 months (range, 0-28 months). All patients underwent various salvage chemotherapies; remission was achieved in 40.5% (15/37). A total of 23 patients received subsequent hematopoietic stem cell transplantations (HSCT): 9 in remission, 12 without remission, and 2 with unknown status. With median follow-up period of 5.5 years, the 5-year overall survival (OS) rate after the second-line treatment was 25.6% +/- 6.9%. Young age (<3 months) and central nervous system involvement at initial diagnosis were associated with poor outcome; however, failure to achieve remission after salvage therapy was the sole independent poor prognostic factor in multivariate analysis (P = 0.01).ConclusionsThe prognosis of infants with recurrent or refractory MLL-R ALL is extremely poor despite alternative treatments including HSCT; therefore, it is necessary to develop novel treatment strategies.(c) 2009 Wiley-Liss, Inc.

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