[Minimal residual disease in acute myeloid leukemia in children--standardization and evaluation of immunophenotyping in the AML-BFM-98 study]

Clinical significance of flowcytometric minimal residual disease detection in pediatric acute myeloid leukemia patients treated according to the DCOG ANLL97/MRC AML12 protocol

Analysis of minimal residual disease (MRD) in childhood acute myeloid leukemia (AML) may predict for clinical outcome. MRD levels were assessed by flowcytometric immunophenotyping in 94 children with AML enrolled into a single trial (United Kingdom Medical Research Council AML12 and similar Dutch Childhood Oncology Group ANLL97). An aberrant immunophenotype could be detected in 94% of patients. MRD levels after the first course of chemotherapy predicted for clinical outcome: 3-year relapse-free survival was 85%+/-8% (s.e.) for MRD-negative patients (MRD<0.1%), 64%+/-10% for MRD-low-positive patients (0.1%<or=MRD<0.5%) and only 14+/-9% for MRD-high-positive patients (MRD>or=0.5%; P<0.001), whereas overall survival was 95%+/-5%, 70%+/-10% and 40%+/-13%, respectively, (P<0.001). Multivariate analysis allowing for age, karyotype, FLT3-internal tandem duplications and white blood cell count at diagnosis showed that MRD after the first course of chemotherapy was an independent prognostic factor. Although comparison of paired diagnosis-relapse samples (n=23) showed immunophenotypic shifts in 91% of cases, this did not hamper MRD analysis. In conclusion, flowcytometric MRD detection is possible in children with AML. The level of MRD after the first course of chemotherapy provides prognostic information that may be used to guide therapy.

Detection of residual B precursor lymphoblastic leukemia by uniform gating flow cytometry

BACKGROUND

Residual disease (RD) is an important prognostic factor in acute lymphoblastic leukemia (ALL). Flow cytometry (FC)-based RD detection is easy to perform, but interpretation requires expert analysis due to individual differences among patients.

PROCEDURE

We focused at the design of standardized and reproducible RD monitoring in ALL. RD was investigated by a uniform gating strategy, which was designed internationally and tested in one center by Ig/TCR rearrangements.

RESULTS

For each gate, positivity cutoff value was assigned using quantification of non-leukemic background. Comparing to Ig/TCR at 0.1% level, 80 of 103 specimens were correctly diagnosed by FC. The predictive value of FC RD at day 15 was then analyzed. In B lineage ALL, day 15 FC significantly correlated with Ig/TCR results at day 33 and/or week 12 (P < 0.01). No significant correlation was found in T lineage ALL.

CONCLUSIONS

Thus, FC with preset uniform gating at day 15 predicts PCR-detectable MRD in B precursor ALL. Presented data may be used to define new polychromatic cytometric diagnostics of MRD including semiautomatic assessment. Pediatr Blood Cancer 2010; 54:62-70. (c) 2009 Wiley-Liss, Inc.

Residual Disease Monitoring in Childhood Acute Myeloid Leukemia by Multiparameter Flow Cytometry: The MRD-AML-BFM Study Group

Purpose

Monitoring of residual disease (RD) by flow cytometry in childhood acute myeloid leukemia (AML) may predict outcome. However, the optimal time points for investigation, the best antibody combinations, and most importantly, the clinical impact of RD analysis remain unclear.

Patients and Methods

Five hundred forty-two specimens of 150 children enrolled in the AML-Berlin-Frankfurt-Muenster (BFM) 98 study were analyzed by four-color immunophenotyping at up to four predefined time points during treatment. For each of the 12 leukemia-associated immunophenotypes and time points, a threshold level based on a previous retrospective analysis of another cohort of children with AML and on control bone marrows was determined.

Results

Regarding all four time points, there is a statistically significant difference in the 3-year event-free survival (EFS) in those children presenting with immunologically detectable blasts at 3 or more time points. The levels at bone marrow puncture (BMP) 1 and BMP2 turned out to have the most significant predictive value for 3-year-EFS: 71% ± 6% versus 48% ± 9%, PLog-Rank = .029 and 70% ± 6% versus 50% ± 7%, PLog-Rank = .033), resulting in a more than two-fold risk of relapse. In a multivariate analysis, using a combined risk classification based on morphologically determined blasts at BMP1 and BMP2, French-American-British classification, and cytogenetics, the influence of immunologically determined RD was no longer statistically significant.

Conclusion

RD monitoring before second induction has the same predictive value as examining levels at four different time points during intensive chemotherapy. Compared with commonly defined risk factors in the AML-BFM studies, flow cytometry does not provide additional information for outcome prediction, but may be helpful to evaluate the remission status at day 28.

Immunophenotypic differences between diagnosis and relapse in childhood AML: Implications for MRD monitoring

BACKGROUND

Determination of antigen expression patterns is, in addition to morphologic analysis, essential to the diagnosis of acute myeloid leukemia (AML). The present study was performed to determine (a) the degree of changes in immunophenotype and their consequences on the monitoring of minimal residual disease (MRD) in childhood AML and (b) whether certain clusters of changes in antigen expression patterns exist between diagnosis and relapse.

METHODS

Bone marrow specimens of 48 children enrolled in the German AML-BFM-93/98 (Acute Myeloid Leukemia-Berlin-Frankfurt-Munster) studies were analyzed immunologically, morphologically, and genetically at diagnosis and at first relapse.

RESULTS

The immunophenotypes by flow cytometry differed by at least one antigen between samples at presentation and relapse in 42 of 48 children (88%). More children displayed an immature phenotype at relapse (43 of 47, 91.5%, vs. 37 of 48, 77%; P = 0.05) with expression of CD34 and/or CD117. This was reflected by a gain of markers that are associated with lineage immaturity in 18 of 25 (72%) of cases, whereas the loss of such antigens was observed in 6 of 25 (24%) patients. We did not observe significant changes for lineage specific markers, with comparable occurrences of loss or gain of myeloid and lymphoid antigens in the sample pairs. Only minimal changes were seen for morphologic and genetic features.

CONCLUSION

An antigenic shift was observed in 88% of cases in this study. The antibody panels used for MRD monitoring in childhood AML should therefore not be restricted to the immunophenotype detected at presentation but should include in particular markers of lineage immaturity. The clinical observation of a shift toward a more immature phenotype of the myeloblasts is consistent with the model of a clonal evolution of a leukemic stem cell.

Aseptic osteonecrosis in children and adolescents treated for hemato-oncologic diseases: a 13-year longitudinal observational study

Aseptic osteonecrosis (AON) is a serious long-term complication of childhood cancer therapy. A retrospective study was undertaken to describe treatment and long-term follow-up of patients with AON. Between 1990 and 2003, 630 consecutive children with various malignancies were treated at the University Children's Hospital in Graz, Austria. In nine of these patients presenting with skeletal symptoms, MRI revealed AON. All nine had hematologic malignancies. The median age at diagnosis of malignancy was 15.8 years (range 13.7-18.6 years), and the median interval between diagnosis of malignancy and onset of osteonecrosis-related symptoms was 16 months (range 6-53 months). All patients had received previous corticosteroid therapy. Treatment of AON included restriction of weight-bearing, physiotherapy, and analgesics. Three patients were treated with hyperbaric oxygen therapy combined with the prostacyclin analog iloprost, and one patient also received pamidronate, a second-generation bisphosphonate. This conservative treatment resulted in alleviation of symptoms in all patients. One patient had to undergo bilateral hip replacement and two had to undergo arthrotomy with sequestrotomy due to subsequent deterioration of symptoms. Close monitoring for skeletal symptoms is mandatory during follow-up of patients with hematologic malignancies. Previous corticosteroid treatment and age older than 10 years seem to be major risk factors. Early detection of AON leading to prompt intervention may prevent more severe morbidity.

Impact of the New Beckman Coulter Cytomics FC 500 5-Color Flow Cytometer on a Regional Flow Cytometry Clinical Laboratory Service

Calgary Laboratory Services (CLS) in Alberta, Canada, is the regional reference laboratory providing flow cytometry services for southern Alberta and southeastern British Columbia. As a busy reference flow laboratory we provide flow cytometry immunophenotyping for investigation and diagnosis of acute and chronic leukemias, lymphomas, immunodeficiencies, neuroblastoma, platelet disorders, and interstitial lung disease (ILD). Because of increasing workload and the continual effort to improve the service to our health care providers, CLS invested in the new Beckman Coulter Cytomics FC 500 5-color flow cytometer. In addition to time and labor savings due to reduced maintenance and operating system design, this new flow cytometer automates many of the previous manual steps involved in quality control and flow cytometric analysis. It also incorporates 2 lasers and is capable of measuring 5-color antibody combinations in a single tube, enabling us to reduce the number of tubes and overall costs, giving us better gating options for minimal residual disease analysis. We present the first published evaluation, an assessment of the overall productivity and cost impact of the new state-of-the-art Cytomics FC 500 flow cytometer. Implementation of the Cytomics FC 500 has resulted in a 20% reduction in reagent costs and shorter turnaround time for analysis and diagnosis. This instrument has allowed us to reduce our acute leukemia panel from 17 to 13 tubes, our lymphoma panel from 13 to 7 tubes, and our ILD panel from 4 to 2 tubes. The availability of 2 lasers provides more flexibility in choosing antibodies and conjugates to customize immunophenotyping panels. It also allows us to use the DRAQ5 dye and simultaneously analyze the immunophenotype and DNA content of cells with very little compensation. Many of the arduous, time-consuming flow operator tasks often associated with previous generation flow cytometry instruments, such as color compensation, list mode analysis, sample repeats, and interpretations, have been substantially reduced with the Cytomics FC 500 5-color flow cytometer. In conclusion the Cytomics FC 500 5-color flow cytometer is a major advance in flow cytometry instrumentation and has reduced our overall reagent costs by 20%, provided better information and speedier turnaround time to our health care professionals. It is an ideal flow cytometer for any busy clinical or research flow cytometry service.

Long-term remission of APL with a second allogeneic BMT after CNS relapse following HLA-identical allogeneic BMT

Second allogeneic bone marrow transplantation (BMT) for AML relapsing after an initial BMT has a poor prognosis, with a probability of a 2-y disease-free survival below 30 per cent, caused both by treatment-related mortality (TRM) and high relapse rate. While TRM is most likely due to heavy pretreatment, AML relapse after BMT may be due to resistant disease or to a poor graft-versus-leukaemia (GvL) effect of the transplant. The degree of GvL may depend on individual donor/recipient immunoreactivity. In most published cases of second allogeneic BMT, both transplants were performed from the same donor. Here, we describe a patient who was first transplanted for acute promyelocytic leukaemia (APL) (AML FAB M3v) from his HLA-identical brother and received intensive immunotherapy including donor lymphocytes and IL2. He remained free from GvHD >I degrees, but developed CNS relapse. After a second BMT from another HLA-identical brother, he spontaneously developed GvHD III degrees, and has now been disease free for nearly 3 years. In this patient, long-term remission of AML relapsing after BMT was achieved by combining remission induction using an individual chemotherapy protocol with a second BMT from an alternative matched related donor and transient GvHD III degrees, which probably conferred a GVL effect.