Minimal residual disease by either flow cytometry or cytogenetics prior to an allogeneic hematopoietic stem cell transplant is associated with poor outcome in acute myeloid leukemia

Relapsed acute myeloid leukemia (AML) is a significant challenge after allogeneic hematopoietic cell transplant (HCT). Multiparameter flow cytometry (MFC), conventional cytogenetics (CG), and fluorescence in situ hybridization (FISH) are routinely performed on bone marrow specimens prior to HCT to assess disease status. We questioned the extent by which pre-HCT evidence of minimal residual disease (MRD) detected by these standard assays, corresponded with post-HCT relapse. We conducted a single center, retrospective study of 166 AML patients who underwent HCT. Thirty-eight of one hundred sixty-six (23%) patients in complete remission (CR) or CR with incomplete count recovery (CRi) had MRD detectable by MFC, CG, or FISH. MRD was more frequently seen in patients with poor risk karyotype at diagnosis (P= 0.011). MRD-negative patients (MRDneg) had significantly longer overall survival (OS) and relapse-free survival than patients who were MRD positive (MRDpos) (P = 0.002 and 0.013, respectively). In patients with MRDpos prior to HCT, the presence of acute graft vs. host disease (GVHD) (grade >= 2) or chronic GVHD significantly improved progression free survival (PFS) (hazard ratio (HR) = 0.053 (95% confidence interval (Cl): 0.01-0.279), P= 0.0005) and OS (HR = 0.211 (95% Cl: 0.081-0.547), P = 0.0014).