Prognostic Impact of Blood Copy Numbers Before Allogeneic Stem Cell Transplantation in Patients With Acute Myeloid Leukemia.

High expression of the leukemia-associated gene meningioma-1 () is frequently found at diagnosis of acute myeloid leukemia (AML) and associates with adverse outcomes. The presence of measurable residual disease (MRD) in complete remission (CR) indicates high risk of relapse and worse outcome in AML patients. However, the prognostic impact of expression levels as MRD marker has not been evaluated. Digital droplet polymerase chain reaction (ddPCR) is a novel technique allowing sensitive and specific absolute gene expression quantification. We retrospectively analyzed 124 AML patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in CR or CR with incomplete peripheral recovery. Absolute copy numbers in peripheral blood were assessed prior to HSCT (median 7; range 0-29 days) using ddPCR. High pre-HSCT /Abelson murine leukemia viral oncogene homolog 1 gene () copy numbers associated with a higher cumulative incidence of relapse after HSCT and-in relapsing patients-shorter time to relapse. In multivariable analysis, high pre-HSCT / copy numbers remained an independent prognosticator for relapse after HSCT. Patients with the highest pre-HSCT / copy numbers also had the highest risk of relapse. copy number assessment also added prognostic information to nucleophosmin 1 gene () mutation- and brain and acute leukemia, cytoplasmic () and Wilm's tumor gene 1 () expression-based MRD evaluation. Our study demonstrates the feasibility of the novel ddPCR technique for / copy number assessment as a marker for MRD. Evaluation of / copy numbers allows the identification of patients at high risk of relapse, independently of other diagnostic risk factors and MRD markers.