High copy numbers in peripheral blood prior to allogeneic transplantation predict early relapse in acute myeloid leukemia patients.

High expression levels at acute myeloid leukemia diagnosis have been linked to adverse outcomes. Recent data indicate that high expression levels may also be used as marker for residual disease following acute myeloid leukemia treatment. Allogeneic hematopoietic stem cell transplantation (HSCT) offers a curative treatment for acute myeloid leukemia patients. However, disease recurrence remains a major clinical challenge and identification of high-risk patients prior to HSCT is crucial to improve outcomes. We performed absolute quantification of copy numbers in peripheral blood prior (median 7 days) to HSCT in complete remission (CR) or CR with incomplete peripheral recovery in 82 acute myeloid leukemia patients using digital droplet PCR (ddPCR) technology. An optimal cut-off of 0.14 / copy numbers was determined and applied to define patients with high or low / copy numbers. High pre-HSCT / copy numbers significantly associated with higher cumulative incidence of relapse and shorter overall survival in univariable and multivariable models. Patients with high pre-HSCT / copy numbers were more likely to experience relapse within 100 days after HSCT. Evaluation of pre-HSCT / copy numbers in peripheral blood by ddPCR represents a feasible and rapid way to identify acute myeloid leukemia patients at high risk of early relapse after HSCT. The prognostic impact was also observed independently of other known clinical, genetic, and molecular prognosticators. In the future, prospective studies should evaluate whether acute myeloid leukemia patients with high pre-HSCT / copy numbers benefit from additional treatment before or early intervention after HSCT.