ISSN 1866-8836
Клеточная терапия и трансплантация

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D. Minimal residual disease

Detection of minimal residual disease (MRD) by flow cytometry in children with acute lymphoblastic leukemia (ALL)

Margarita G. Bozhieva, Ludmila Y. Grivtsova, Alexander V. Popa, Irina N. Serebryakova, Irina E. Gavrilova, Boris V. Kurdyukov, Rono S. Ravshanova, Georgiy L. Mentkevich, Nikolay N. Tupitsyn

Comparison of MRD data assessed by flow cytometry and RT-PCR of fusion gene transcripts in infants with MLL-rearranged ALL

Alexander M. Popov1,2,3, Grigory A. Tsaur1,2, Anna S. Ivanova1,2, Yulia A. Yakovleva1,2, Tatiana Y. Verzhbitskaya1,2, Tatiana O. Riger1, Egor V. Shorikov1,2, Leonid I. Savelyev1,2,3, Larisa G. Fechina1,2

Slow fusion gene transcript clearance predicts poor outcome in infants with MLL-rearranged acute lymphoblastic leukemia

Grigory A. Tsaur1,2, Tatyana V. Nasedkina3, Alexander M. Popov1,2,4, Anna S. Ivanova1,2, Yulia A. Yakovleva1,2, Tatyana O. Riger1,2, Egor V. Shorikov1,2, Leonid I. Saveliev1,2,4, Larisa G. Fechina1,2

Algorithm for monitoring minimal residual disease on the basis of patient-associated immunophenotypes

Yekaterina E. Zueva, Margarita V. Gorchakova, Ekaterina B. Rusanova, Konstantin U. Slobodnyuk

D. Minimal residual disease

Detection of minimal residual disease (MRD) by flow cytometry in children with acute lymphoblastic leukemia (ALL)

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Margarita G. Bozhieva, Ludmila Y. Grivtsova, Alexander V. Popa, Irina N. Serebryakova, Irina E. Gavrilova, Boris V. Kurdyukov, Rono S. Ravshanova, Georgiy L. Mentkevich, Nikolay N. Tupitsyn

Pediatric Oncology and Hematology Research Institute, N. N. Blokhin RCRC RAMS, Moscow, Russia

Background

The initial response of leukemia cells to treatment has consistently been shown to be a reliable prognostic indicator, and its evaluation has been significantly enhanced by methods that allow detection of submicroscopic levels of leukemia.

Methods

From January 2007 to April 2009, 45 patients with newly-diagnosed ALL were enrolled in ALL-IC BFM 2002 studies at our institution and had residual disease studies by flow cytometry on day 15 and day 33 of treatment. Of the 45 patients, 37 patients (82.2%) had a BCP-ALL and 8 had T-ALL (17.8%). Analyses were performed on a FACScan (Becton Dickinson). We used several standardized antibody combinations to screen ALL samples at diagnosis for leukemia-associated aberrations as well as to investigate BM.

Results

In 40 samples (88.9%) on day 15 we identified at least 0.01% leukemic cells (0.01% – <0.1% in 12 (26.7%), 0.1% – <1% in 16 (35.6%), and  ≥ 1% in 12 (26.7%). Of the 45 bone marrow samples studied by flow cytometry on day 15 of remission–induction therapy, 11 (24.4%) had leukemic lymphoblasts identifiable by morphologic analysis. In all the 11 morphologically positive samples, at least 0.1% cells expressing leukemia-specific immunophenotypes were detected by flow cytometry (median 17.2%, range 0.37% to 82.2%). Among the 34 (75.6%) samples without leukemic lymphoblasts recognizable by their morphologic features, 29 (64.5%) had detectable cells expressing leukemia-associated immunophenotypes (median 1.4%, range 0.01% to 25%).

Conclusion

The proportion of samples that were MRD+ was high on day 15 and decreased to 59.6% on day 33. Children with ALL who achieved an early clearance of leukemic cells had an excellent outcome.

Keywords

acute lymphoblastic leukemia, children, minimal residual disease, flow cytometry

D. Minimal residual disease

Comparison of MRD data assessed by flow cytometry and RT-PCR of fusion gene transcripts in infants with MLL-rearranged ALL

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Alexander M. Popov1,2,3, Grigory A. Tsaur1,2, Anna S. Ivanova1,2, Yulia A. Yakovleva1,2, Tatiana Y. Verzhbitskaya1,2, Tatiana O. Riger1, Egor V. Shorikov1,2, Leonid I. Savelyev1,2,3, Larisa G. Fechina1,2

1Pediatric Oncology and Hematology Center, Regional Children’s Hospital, Ekaterinburg, Russia; 2Research Institute of Medical Cell Technologies, Ekaterinburg, Russia; 3Ural State Medical Academy, Ekaterinburg, Russia

Correspondence
Alexander M. Popov, Regional Children’s Hospital, Pediatric Oncology & Hematology Center, S. Deryabina Street 32, 620149 Ekaterinburg, Russia, Phone: +7 (908) 9037736, Fax: +7 (343) 2162517
E-mail: uralflow@spam is badgmail.com

Aim

To evaluate qualitative and quantitative concordance between MRD data assessed by flow cytometry (FC) and fusion gene transcript (FGt) copy number (CN) measured by real-time quantitative PCR (RQ-PCR) in infants with primary and relapsed MLL-rearranged ALL during treatment.

Methods

A tandem application of multicolor FC for MRD detection and RQ-PCR for FGt CN was performed in 72 follow-up bone marrow samples from 15 infants with MLL-rearranged B-lineage ALL. Twenty samples were obtained during remission induction, 36 during postinduction, and 16 during relapse treatment.

Results

Of the 72 samples, 7 (9.72%) were MRD-negative by both methods, while 2 (2.78%) were negative by FC but positive by RQ-PCR. The remaining 63 samples (87.50%) were MRD-positive by both methods. High qualitative concordance (97.22%) between FC and RQ-PCR was obtained. In contrast, low quantitative concordance was found (r=0.54). The significant quantitative difference in FC and RQ-PCR data could be associated with variability of FG expression during treatment that does not correspond to the cell number. Moreover, during FC the MRD detection percentage of tumor blasts among all nucleated cells is calculated, while the MRD value in RQ-PCR of FGt corresponds to the initial FGt and control gene levels. FC appears to be better for a quantitative MRD assessment; however FGt detection in RQ-PCR is more appropriate for MRD qualitative analysis because of its higher sensitivity. Hence, FC is more applicable for early treatment stratification and RQ-PCR of FGt for later time points.

Conclusion

A tandem application of FC at early time points and FGt detection by RQ-PCR at later time  points seems to be a useful tool for MRD monitoring in infants with MLL rearranged ALL.

Keywords

MRD, MLL, infants, flow cytometry, fusion gene transcript

D. Minimal residual disease

Slow fusion gene transcript clearance predicts poor outcome in infants with MLL-rearranged acute lymphoblastic leukemia

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Grigory A. Tsaur1,2, Tatyana V. Nasedkina3, Alexander M. Popov1,2,4, Anna S. Ivanova1,2, Yulia A. Yakovleva1,2, Tatyana O. Riger1,2, Egor V. Shorikov1,2, Leonid I. Saveliev1,2,4, Larisa G. Fechina1,2

1Regional Children Hospital 1, Ekaterinburg, Russia; 2Research Institute of Medical Cell Technologies, Ekaterinburg, Russia; 3Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia; 4Ural State Medical Academy, Ekaterinburg, Russia

Correspondence
Grigory Tsaur, Regional Children Hospital №1, Pediatric Oncology & Hematology Center
S. Deryabina Street 32, 620149 Ekaterinburg, Russia, Phone: +7-343-216-2517, Fax: +7-343-216-2517
E-mail: grigory.tsaur@spam is badgmail.com

Objective

To find out a single time point (TP) for fusion gene transcript (FGt) monitoring by RT-PCR that clearly predicts the outcome in infants with MLL-rearranged ALL. All patients (pts) were treated by MLL-Baby protocol, containing all-trans retinoic acid (ATRA).

Methods

The monitoring of FGt was performed in 18 infants with defined MLL translocation partner genes and more than 4 follow-up samples. MRD-negativity was defined as an absence of FGt in nested RT-PCR with sensitivity of 1E-5. The median of follow-up was 25 months. There were
11 MLL-AF4-positive pts, 3 MLL-MLLT10-positive, 2 MLL-EPS15-positive, 1 MLL-MLLT1-positive patient, and 1 MLL-MLLT3-positive patient. Bone marrow samples were obtained at diagnosis, on day 15 of remission induction (TP1), end of remission induction (TP2), one week after first ATRA administration (TP3). In MLL-AF4-positive pts following TPs (TP4–TP9) were scheduled before each HR block. In all other pts the presence of FGt was estimated before each reinduction (TP4-TP6).

Results

FGt elimination speed does not correlate to any known prognostic factors. Retrospectively, patients were divided into 2 groups. The first group included 14 patients who achieved molecular remission by TP4, while 2 relapses occurred (MLL-AF4-positive and MLL-EPS15-positive). The second group consisted of 4 MLL-AF4-positive pts who did not achieve molecular remission by TP4; there were 3 relapses. The number of relapses in this group was significantly higher (p=0.04). The 70-month RFS in the first group was 0.84, in the second group 0.25 (p=0.02). The cumulative incidence of relapse in the first group was 0.15, in the second group 0.75 (p=0.02)

Conclusions

The presence of FGt by TP4 helps to identify pts with a high risk of relapse.

Keywords

ALL, infants, MLL rearrangements, fusion gene transcripts, MRD monitoring

D. Minimal residual disease

Algorithm for monitoring minimal residual disease on the basis of patient-associated immunophenotypes

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Yekaterina E. Zueva, Margarita V. Gorchakova, Ekaterina B. Rusanova, Konstantin U. Slobodnyuk

Department of Clinical Laboratory Diagnostics, Center for Laboratory Diagnostics, St. Petersburg Pavlov State Medical University,
St. Petersburg, Russia

Correspondence
Yekaterina E. Zueva, Department of Clinical Laboratory Diagnostics, Center for Laboratory Diagnostics, St. Petersburg Pavlov State Medical University, 6/8, Tolstoy str., St. Petersburg, 199044, Russia
E-mail: yekaterina.zueva@spam is badgmail.com

Aims

Algorithm for monitoring MRD on the basis of patient-associated immunophenotypes.

MRD monitoring aims to identify cells with aberrant or rare phenotypes. It is appropriate to use patient-associated panels for MRD monitoring, which include: (i) phenotypic markers of transformed cells identified at the date of primary diagnostics, and (ii) markers often occurring in a particular variant of AL. Immunological MRD monitoring is an individualized laboratory diagnostic, since individual patients could have a complete preservation of aberrant phenotypes of transformed cells, as well as changes in the expression of some markers.

Methods

A multicolor flow cytometry was used.

Results

Seventy-five cases of primary pediatric AL were studied. Among them were 53 cases of B-ALL, 8 cases of T-ALL, and 13 cases of AML. Monitoring of MRD was performed in 23 B-ALL cases, 6 T-ALL cases, and 5 AML cases.

During MRD monitoring, we observed the complete preservation of phenotypes of transformed cells in 11 cases of B-ALL (48% of cases) and 4 cases of a change in expression (17%). In other cases, MRD of B-ALL was not detected (35%). Complete preservation of phenotypes of transformed cells was observed in 3 cases of T-ALL (50%) and in 3 cases MRD was not identified (50%). Complete preservation of cell phenotypes was observed in 3 cases of AML (60%), while in 2 cases (40%) a change in expression was revealed.

Summary

An algorithm for monitoring MRD on the basis of patient-associated immunophenotypes allows the verification of MRD through the presence of malignant cells with a sensitivity up to 10-5. This algorithm provides full information to clinicians, and thus the possibility to plan transplantations.

Keywords

MRD, flow cytometry, ALL, patient-associated algorithm, monitoring