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Detection of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia by 4color Cytometry in International Multicenter Trial Minimini (CROSBI ID 511044)

Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija

Mejstrikova, Ester ; Batinic, Drago ; Dubravcic, Klara et al. Detection of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia by 4color Cytometry in International Multicenter Trial Minimini // Blood. 2004

Podaci o odgovornosti

Mejstrikova, Ester ; Batinic, Drago ; Dubravcic, Klara et al.

engleski

Detection of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia by 4color Cytometry in International Multicenter Trial Minimini

Although flow cytometry (FC) has the capacity to be a standardized technique, most published studies are limited to one laboratory and despite encouraging published studies, FC is usually not considered a method of choice for minimal residual disease (MRD) evaluation (e.g. Dworzak at al., 2002). One problem is that the specific route to the MRD results is often unclear in the published FC trials. Therefore, we established a MiniMini Project, an international collateral study within the ALL IC BFM 2002 treatment protocol for childhood acute lymphoblastic leukemia (ALL). The MiniMini Project provides a mainframe of minimal panel of monoclonal antibody combinations to evaluate MRD by FC (4 combinations in B lineage and 3 combinations in T lineage). Uniform templates are used for analyses. The ALL IC BFM 2002 protocol started in November 2002. Patients are stratified according to non-MRD criteria (prednisone response at day 8, percentage of blasts at day 15 and day 33 in bone marrow (BM), leucocytosis, and age at diagnosis and presence of BCR/ABL or MLL/AF4 fusions). In parallel to the MiniMini Project, a MiniRisk Project is running that evaluates MRD by standard PCR-based immunoreceptor gene rearrangements quantification. Reference labs from Croatia, Czech Republic, Hong Kong, Hungary and Israel participate in the Project. Identical immunophenotypic populations (31 populations in B lineage, 8 in T lineage) are reported in all patients regardless presenting phenotype. In addition, each laboratory investigates at least 2 patients with B lineage ALL by the T ALL combinations and vice versa. These “ cross-lineage controls” together with data on subpopulations that are negative at diagnosis were used to set the specificity cutoff values at each time point (diagnosis, day 8 peripheral blood, day 15, day 33 day 52 BM). The knowledge on MRD levels obtained by PCR in 32 patients (24 pts BCP ALL, 8 pts T ALL) was used to define specificity thresholds. Gate positions where antigen overexpression (CD10, CD66c and CD58) is considered are synchronized using QSC beads with defined capacity to bind mAb molecules. We correlated all values with PCR, morphology and definitive patient’ s stratification. At the time of abstract submission, 185 patients were investigated in the participating laboratories (160 B lineage, 25 T lineage). We used data from first Czech cohort of patients (92 pts in total, 16 pts T lineage, 74 pts B lineage, in standard risk group (SRG, n=36), IRG, n=40 and HRG, n=16) in whom clinical data as well as standard FC analysis results were available. The stratification is partly based on BM morphology at day 15 and day 33. We compared percentage of blasts by morphology at day 15 and 33 with level of residual disease by FC. At day 15, 4 patients in the SRG had FC BM involvement between 5 and 25% (corresponding to the M2 definition by morphology). In addition, one patient was redirected into the IRG because of M3 BM, whereas her FC involvement reached only 14%. Three other patients in the IRG (7.5%) BM involvement by FC higher than 25% but their BM morphology was M2. All other differences between FC and morphology did not have an impact on RG assignment. Although FC data confirm a significant difference between PGR and PPR in PB specimens of day 8 (p=0.0014), there is an overlap in percentage of leukemic cells between these categories. In total, MRD level above 0.1% was observed in BM of 100, 99, 84, 32 and 3.5 % patients in days 0, 8, 15, 33 and 52, respectively and in PB of 95% patients at day 8. Regeneration pattern at day 52 reduces specificity of particular populations. Our first results show feasibility of FC standardization. The choice of subpopulations and the cutoff points will be validated in an independent cohort within the same Project.

Standardization; Flow cytometry

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Podaci o prilogu

2004.

objavljeno

Podaci o matičnoj publikaciji

Blood

Podaci o skupu

46th ASH meeting

poster

04.12.2004-07.12.2004

San Diego (CA), Sjedinjene Američke Države

Povezanost rada

Temeljne medicinske znanosti