Flow cytometry minimal residual disease assessment in peripheral blood of adult acute lymphoblastic leukemia patients.

e18517Background: Multiparametric flow cytometry (FC) of bone marrow aspirate (BM) is a widely used method of minimal residual disease (MRD) assessment in acute lymphoblastic leukemia (ALL). In practice, ALL with hematogone-like phenotype and patients with recurrence of isolated extramedullary disease present challenges in accurate determination of MRD status. We hypothesized that addition of FC MRD of peripheral blood would aid in the interpretation of MRD status. Methods: 76 matched BM and PB specimens were analyzed independently for presence of ALL MRD by 6-color FC. Results: The overall rate of BM MRD-positivity was 24% (18/76) and PB was also MRD-positive in 22% (4/18) of BM-positive cases. PB MRD sensitivity and specificity relative to BM MRD was 13% [95% confident interval (CI) 2%-42%] and 98% [88-100%] for B-ALL samples (n = 65) and 67% [13%-98%] and 75% [36%-95%] for T-ALL samples (n = 11), respectively. We identified 2 cases with evidence of leukemic cells in PB at the time of the extramedullary...