Presence of minimal residual disease (MRD) in acute myelogenous leukemia (AML) patients preallogeneic bone marrow transplantation (BMT) is associated with a lower relapse-free survival (RFS)

We evaluated whether the presence of MRD detected by flow cytometry pre-BMT in patients (pts) with AML who were in complete remission (CR) by morphologic criteria was associated with an increased relapse rate after related allogeneic HLA-identical BMT Twenty-eight consecutive pts who had undergone allogeneic BMT with a median follow up of 31 months, (range, 10-64) were evaluated. The treatment regimen was either busulfan (Bu) and Cyclophosphamide (Cy) (n=2) or Bu, Cy and cytarabine (n=26). Twenty-one patients were in first CR (CRI) and 7 were in CR2. Disease status by FAB classification were 4 MO, 5 Ml, 7 M2, 3 M3, 6 M4, 1 M5, 1 M6 and I unclassified. Their median age was 46 yr (range, 20-62). All pts had bone marrow aspirates performed within 4 weeks before BMT and had flow cytometry analysis performed using a panel of monoclonal antibodies to myeloid antigens. The sensitivity of identifying a clonal cell population was approximately 0.1% of gated cells. For this analysis, the bone marrow results for the detection of MRD were grouped as being either negative (n = 11), < 1% (n = II), or 1% to 3% (n = 6). The RFS for pts without detectable MRD versus detectable MRD were 80% and 65%, respectively (p = .06). The RFS for patients with no MRD versus <1% MRD were 80% and 85%, respectively (p = >0.5). The RFS for patients with either no MRD and < 1% MRD versus > 1% MRD were 83% and 50%, respectively (p = .01); however, presence or absence of MRD did not influence overall survival: (53% versus 50%, respectively; p = 0.51). In summary, the detection of ?1% MRD was associated with a significantly lower RFS. There was no adverse outcome observed with patients who had < 1% MRD detected when compared to patients with no detectable MRD.