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Clinical outcome and monitoring of minimal residual disease in patients with acute lymphoblastic leukemia expressing the MLL/ENL fusion gene
Author(s) -
Elia Loredana,
Grammatico Sara,
Paoloni Francesca,
Vignetti Marco,
Rago Angela,
Cenfra Natalia,
Mecarocci Sergio,
Mancini Marco,
Luciani Matteo,
Di Raimondo Francesco,
Cazzaniga Giovanni,
Matarazzo Mabel,
Moleti Maria Luisa,
Santoro Lidia,
Gaidano Gianluca,
Foà Robin,
Mandelli Franco,
Cimino Giuseppe
Publication year - 2011
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.22161
Subject(s) - minimal residual disease , immunophenotyping , fusion gene , medicine , complete remission , leukemia , acute leukemia , gastroenterology , lymphoblastic leukemia , preleukemia , disease , acute lymphocytic leukemia , gene rearrangement , immunology , oncology , gene , biology , flow cytometry , chemotherapy , genetics
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. Am. J. Hematol. 2011. © 2011 Wiley‐Liss, Inc.