Clinical Analysis of Adult Acute Leukemia with Rearrangements of the 11q23/MLL: Multicenter Co-Operative Study.

Background AL(acute leukemias) with 11q23 abnormalities involving the MLL (mixed lineage leukemia) gene comprise one category of recurring genetic abnormalities in the WHO classification. However, the prognosis of adult AL with 11q23/MLL between fusion partners are controversial especially in Asia.

Methods We analyzed data on 61 Japanese adult patients diagnosed as AL with 11q23/MLL abnormalities, including the translocations t(4;11), t(9;11), t(6;11), t(11;19) between 1990 and 2006.

Results Median age of the 61 patients was 48 years (range, 17–79 years). 54 patients were AML (acute myeloid leukemia) and 7 patients were ALL (acute lymphoblastic leukemia).The incidence by fusion partners in AML were as follows; t(9;11) in 29.6%, t(11;19) in 24.0%, t(6;11) in 18.5%. The incidence of patients with t(11;19) was higher than that in Caucasian and t(4;11) was lower than that in childhood. As for the FAB (French-American-British) subtype, 68.5% of the 11q23/MLL patients were M4/M5. Organ involvement was observed commonly (46.2%) in AML with 11q23/MLL patients except for t(11;19) (7.6%).The CR (complete remission) rate of AML with 11q23/MLL was not low (78.7%), but the CR duration was very short (10 months).The DFS (disease free survival) at 1year and the OS (overall survival) at 2 years were 20% and 30% in AML with t(9;11), 10% and 19% in AML with t(11;19), 10% and 30% in AML with t(6;11). In total, the DFS at 1year and the OS at 2 years were 26% and 25% in AML patients, respectively, while 50% and 50% in ALL patients, respectively. The DFS and the OS at 2 years were 44% and 53% in AML patients with 11q23/MLL who were treated with HSCT(hematopoietic stem cell transplantations), while 14% and 21% in those without HSCT respectively.

Conclusions Although there were reports that the prognosis of AML with t(9;11) was not bad in Caucasian, the present study showed poor prognosis of AML with 11q23/MLL in Japanese adult patients regardless of the fusion partners. Our study revealed the short CR duration of the AML patients with 11q23/MLL in the face of the high CR rate. AML patients with 11q23/MLL who were treated with HSCT had superior outcomes to those without HSCT (P=.04 for DFS and P=.04 for OS) .This findings suggest that treatment strategies including HSCT should be considered for AML with 11q23/MLL during the first CR.