Clinical outcome and monitoring of minimal residual disease in patients with acute lymphoblastic leukemia expressing the MLL/ENL fusion gene

Loredana Elia, Sara Grammatico, Francesca Paoloni, Marco Vignetti, Angela Rago, Natalia Cenfra, Sergio Mecarocci, Marco Mancini, Matteo Luciani, Francesco Di Raimondo, Giovanni Cazzaniga, Mabel Matarazzo, Maria Luisa Moleti, Lidia Santoro, Gianluca Gaidano, Robin Foà, Franco Mandelli, Giuseppe Cimino

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Abstract

We analyzed 12 MLL/ENL positive ALL patients consecutively diagnosed between 1999 and 2009. The MLL/ENL fusion was identified in 4/150 (2.6%), 8/993 (0.8%), and 0/70 of pediatric, adult, and elderly patients, respectively. Eight patients had a WBC count >50 × 10 9/L. Ten cases had an evaluable immunophenotyping. A B or T precursor ALL occurred in 7 and 3 patients, respectively. Eleven/12 patients (92%) achieved CR. At 48 months, overall survival and event-free survival rates were 73.3% and 67%, respectively. At CR, a parallel RT-PCR evaluation of the MLL/ENL expression was available in 5 cases. Of these latter, 2 tested MLL/ENL-negative and 3 positive. The minimal residual disease molecular monitoring showed that MLL/ENL status did not correlate with outcome. In fact, all the 2 PCR-negative and 1 of the 3 PCR-positive cases relapsed. Further, a MLL/ENL expression, not preceding a relapse, was detected several times during the follow-up of five long-survivors. In conclusion, also in adults, the MLL/ENL fusion identifies a rare leukemic entity with a favorable prognosis. The observed inconsistency between the clinical cure and the presence of detectable MLL/ENL transcript suggests the existence of a MLL/ENL-expressing "preleukemia" stem cells, similar to what demonstrated for the AML1/ETO-positive leukemia setting.

Original languageEnglish
Pages (from-to)993-997
Number of pages5
JournalAmerican Journal of Hematology
Volume86
Issue number12
DOIs
Publication statusPublished - Dec 2011

ASJC Scopus subject areas

  • Hematology

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    Elia, L., Grammatico, S., Paoloni, F., Vignetti, M., Rago, A., Cenfra, N., Mecarocci, S., Mancini, M., Luciani, M., Di Raimondo, F., Cazzaniga, G., Matarazzo, M., Moleti, M. L., Santoro, L., Gaidano, G., Foà, R., Mandelli, F., & Cimino, G. (2011). Clinical outcome and monitoring of minimal residual disease in patients with acute lymphoblastic leukemia expressing the MLL/ENL fusion gene. American Journal of Hematology, 86(12), 993-997. https://doi.org/10.1002/ajh.22161