Therapy-induced Acute Lymphocytic Leukemia with the 11q23 Translocation: 2 Cases and a Review of the Literature

We report two cases of therapy-induced ALL (t-ALL) with the 11q23 translocation (Mixed Lineage Leukemia or MLL rearrangement). Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are well known to occur in patients who had previously received topoisomerase II inhibitors or alkylating agents for the treatment of a prior malignancy. t- ALL, however, is a rare entity. Similar to therapy- induced AML (t-AML) or MDS; t-ALL can also be associated with the11q23 translocation. This translocation typically occurs in t-AML secondary to prior DNA topoisomerase II inhibitor therapy. We present two uniquecases of t-ALL along with the literature review of 30 previously reported t-ALL cases associated with the 11q23 translocation. A balanced translocation at the 11q23 region was observed in most cases as in our review. The MLL gene at locus 11q23 was observed to have a break point in the majority of analyzed cases at a site similar to t-AML. All the t-ALL cases reviewedwith the 11q23 translocation were secondary to prior topoisomerase II inhibitor therapy. The diagnosis of t-ALL was made at a median time point of 19 months from prior therapy. t-ALL, similar to t-AML with an 11q23 translocation, is associated with a poor prognosis. These patients should be considered for allogeneic stem cell transplantation in first complete remission. This therapeutic approach may improve the long term overall survival. However, given the dearth of clinical trials in this select population, further clinical studies need to be done to validate this approach.