title: Improved flow cytometric detection of minimal residual disease in childhood acute lymphoblastic leukemia.
abstract: Most current treatment protocols for acute lymphoblastic leukemia (ALL) include minimal residual disease (MRD) diagnostics, generally based on PCR analysis of rearranged antigen receptor genes. Although flow cytometry (FCM) can be used for MRD detection as well, discordant FCM and PCR results are obtained in 5-20% of samples. We evaluated whether 6-color FCM, including additional markers and new marker combinations, improved the results. Bone marrow samples were obtained from 363 ALL patients at day 15, 33 and 78 and MRD was analyzed using 6-color (218 patients) or 4-color (145 patients) FCM in parallel to routine PCR-based MRD diagnostics. Compared with 4-color FCM, 6-color FCM significantly improved the concordance with PCR-based MRD data (88% versus 96%); particularly the specificity of the MRD analysis improved. However, PCR remained more sensitive at levels <0.01%. MRD-based risk groups were similar between 6-color FCM and PCR in 68% of patients, most discrepancies being medium risk by PCR and standard risk by FCM. Alternative interpretation of the PCR data, aimed at prevention of false-positive MRD results, changed the risk group to standard risk in half (52%) of these discordant cases. In conclusion, 6-color FCM significantly improves MRD analysis in ALL but remains less sensitive than PCR-based MRD-diagnostics.
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Denys
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Sluijs-Gelling
authors.forename: C
authors.initials: C
authors.lastname: Homburg
authors.forename: C E
authors.initials: CE
authors.lastname: van der Schoot
authors.forename: V
authors.initials: V
authors.lastname: de Haas
authors.forename: J
authors.initials: J
authors.lastname: Philippé
authors.forename: R
authors.initials: R
authors.lastname: Pieters
authors.forename: J J M
authors.initials: JJ
authors.lastname: van Dongen
authors.forename: V H J
authors.initials: VH
authors.lastname: van der Velden
mesh_terms: D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology; D002648:Child; D004273:DNA, Neoplasm / Q000235:genetics; D005434:Flow Cytometry; D005500:Follow-Up Studies; D006801:Humans; D016130:Immunophenotyping; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D004273:DNA, Neoplasm