Brigitte Mohr

Rapid quantification of mixed chimerism using multiplex amplification of short tandem repeat markers and fluorescence detection

Monitoring the engraftment of donor cells after allogeneic blood stem cell transplantation (BSCT) may be important for the early diagnosis of graft failure or relapse of disease. Several techniques have been reported for this purpose. PCR-based assays analyzing polymorphic short tandem repeat (STR) markers are attractive because they are sensitive and can be performed rapidly. The intent of the present study was to test a novel approach for the quantification of mixed chimerism using a commercial multiplex STR assay with fluorescence-based detection for forensic purposes. The feasibility of this assay and the accuracy of quantitative results was tested using serial cell mixtures of unrelated individuals. Sample preparation was optimized to obtain information from minute amounts of starting material, eg from patients with aplasia or from sorted cell populations. Using the STR-PCR, discrimination between donor and recipient was possible in all patients analyzed (n = 25). Cell dilution experiments showed a linear correlation between the cell numbers added and the proportions found, with the limit of detection for a minor cell population being 5%. Comparison of values obtained with standard FISH analysis in patients transplanted from sex-mismatched donors showed an excellent correlation with the STR-PCR results. Taken together, this procedure allows the rapid, versatile and accurate quantification of mixed chimerism, even with minuscule numbers of cells.

Azacitidine for treatment of imminent relapse in MDS or AML patients after allogeneic HSCT: results of the RELAZA trial

This study evaluated azacitidine as treatment of minimal residual disease (MRD) determined by a sensitive donor chimerism analysis of CD34+ blood cells to pre-empt relapse in patients with CD34+ myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (HSCT). At a median of 169 days after HSCT, 20/59 prospectively screened patients experienced a decrease of CD34+ donor chimerism to <80% and received four azacitidine cycles (75 mg/m2/day for 7 days) while in complete hematologic remission. A total of 16 patients (80%) responded with either increasing CD34+ donor chimerism to ⩾80% (n=10; 50%) or stabilization (n=6; 30%) in the absence of relapse. Stabilized patients and those with a later drop of CD34+ donor chimerism to <80% after initial response were eligible for subsequent azacitidine cycles. A total of 11 patients (55%) received a median of 4 (range, 1–11) additional cycles. Eventually, hematologic relapse occurred in 13 patients (65%), but was delayed until a median of 231 days (range, 56–558) after initial decrease of CD34+ donor chimerism to <80%. In conclusion, pre-emptive azacitidine treatment has an acceptable safety profile and can substantially prevent or delay hematologic relapse in patients with MDS or AML and MRD after allogeneic HSCT.

Sequential monitoring of chimerism and detection of minimal residual disease after allogeneic blood stem cell transplantation (BSCT) using multiplex PCR amplification of short tandem repeat-markers.

Sequential analysis of chimerism after allogeneic blood stem cell transplantation (BSCT) has been shown to be predictive for graft failure and relapse. We have explored the impact of a novel approach for the quantitative determination of chimerism using a commercial PCR assay with multiplex amplification of nine STR-loci and fluorescence detection. The feasibility was studied in 121 patients transplanted from related or unrelated donors. Follow-up investigation was performed in 88 patients. Twenty-eight of these patients had received a transplantation after dose-reduced conditioning therapy. Results were compared to data obtained by FISH analysis in a subgroup of patients receiving grafts from sex-mismatched donors. The analysis was possible in all patients, the median number of informative alleles was 4 (range 1–8) compared to 7 (range 1–9) in the related and unrelated situation, respectively. A good correlation was seen in 84 samples from 14 patients analyzed in parallel with STR-PCR and FISH. Decreasing values of donor chimerism were detected prior to or concomitantly with the occurrence of graft failure and relapse of disease in all patients investigated prospectively. Using FACS-sorted material, eg peripheral blood CD34+ cells, the assay permitted the detection of residual recipient cells with high sensitivity (down to one CD34+ Kasumi cell in 40 000 normal WBC). Evaluation of the inter-laboratory reproducibility revealed that in 20 samples analyzed in three different centers, the median coefficient of variation was 2.1% (range 0.7–9.6%). Taken together, the results support the use of the test as a valuable tool in the follow-up of patients undergoing allogeneic BSCT. In cases lacking PCR-detectable disease-specific gene products, this assay may represent an alternative to recently established real-time PCR methods.

Allogeneic Hematopoietic Stem-Cell Transplantation for Chronic Lymphocytic Leukemia With 17p Deletion: A Retrospective European Group for Blood and Marrow Transplantation Analysis

PURPOSE Patients with chronic lymphocytic leukemia (CLL) and 17p deletion (17p-) have a poor prognosis. Although allogeneic hematopoietic stem-cell transplantation (HCT) has the potential to cure patients with advanced CLL, it is not known whether this holds true for patients with 17p-CLL. PATIENTS AND METHODS Baseline data from patients, for whom information on the presence of 17p-CLL was available, were downloaded from the European Group for Blood and Marrow Transplantation database. Additional information on the course of CLL and follow-up was collected with a questionnaire. RESULTS A total of 44 patients with 17p-CLL received allogeneic HCT between March 1995 and July 2006 from a matched sibling (n = 24) or an alternative donor (n = 20). 17p-CLL had been diagnosed by fluorescent in situ hybridization in 82% of patients and by conventional banding in 18% of patients. The median age was 54 years. Before HCT, a median of three lines of chemotherapy had been administered. At HCT, 53% of patients were in remission. Reduced-intensity conditioning was applied in 89% of patients. Acute, grade 2 to 4 graft-versus-host disease (GVHD) occurred in 43% of patients, and extensive chronic GVHD occurred in 53% of patients. At last follow-up, 19 patients were alive, with a median observation time of 39 months (range, 18 to 101 months). Three-year overall survival and progression-free survival rates were 44% and 37%, respectively. The cumulative incidence of progressive disease at 4 years was 34%. No late relapse occurred in nine patients with a follow-up longer than 4 years. CONCLUSION Allogeneic HCT has the potential to induce long-term disease-free survival in patients with 17p-CLL.

Long-Term Prognosis of Acute Myeloid Leukemia According to the New Genetic Risk Classification of the European LeukemiaNet Recommendations: Evaluation of the Proposed Reporting System

PURPOSE The current European LeukemiaNet (ELN) recommendations for acute myeloid leukemia (AML) propose a new risk reporting system, integrating molecular and cytogenetic factors and subdividing the large heterogenous group of intermediate-risk patients into intermediate-I (IR-I) and intermediate-II (IR-II). We assessed the prognostic value of the new risk classification in a large cohort of patients. PATIENTS AND METHODS Complete data for classification were available for 1,557 of 1,862 patients treated in the AML96 trial. Patients were assigned to the proposed genetic groups from the ELN recommendations, and survival analyses were performed using the Kaplan-Meier method and log-rank test for significance testing. RESULTS The median age of all patients was 67 years. With a median follow-up of 8.3 years, significant differences between all risk categories were observed in patients age ≤ 60 years regarding the time to relapse, relapse-free survival, and overall survival (OS). Patients in the IR-II group had a better prognosis than patients in the IR-I group. The median OS times in young patients with favorable risk (FR), IR-I, IR-II, and adverse risk (AR) were 5.3, 1.1, 1.6, and 0.5 years, respectively. Separate analyses in the age group older than 60 years revealed significant differences between FR, AR, and IR as a whole, but not between IR-I and IR-II. CONCLUSION In younger patients with AML, the ELN classification seems to be the best available framework for prognostic estimations to date. Caution is advised concerning its use for prospective treatment allocation before it has been prospectively validated. In elderly patients, alternative prognostic factors are desirable for further risk stratification of IR.

The prognostic impact of 17p ( p53 ) deletion in 2272 adults with acute myeloid leukemia

Loss of p53—a tumor suppressor gene located on the short arm of chromosome 17 (band 17p13.1)—was detected in 105 out of 2272 (5%) adult acute myeloid leukemia (AML) patients who took part in the Study Alliance Leukemia AML96 and AML2003 multi center trials. There were 85 patients with 17p (p53) deletion with multiple aberrations and 20 patients with a 17p (p53) deletion as single aberration or with only one additional chromosomal abnormality. None of the p53-deleted patients displayed additional low-risk aberrations, like t(8;21) or inv(16). Significant positive association between p53 deletion and other high-risk factors was identified for del(5q) (P<0.001), −5 (P<0.001) and −7 (P<0.05). The molecular risk factors FLT3-ITD and NPM1 mutation showed an inverse correlation to the p53 deletion in complex aberrant patients (P<0.001). The multivariate analysis revealed p53 deletion without multiple aberrations as an independent negative prognostic factor for disease-free survival (P<0.001), relapse risk (P=0.028) and overall survival (P<0.001). Thus, the single p53 deletion should be considered as a high-risk aberration for future risk-adapted treatment strategies in AML.

Comparison of spectral karyotyping and conventional cytogenetics in 39 patients with acute myeloid leukemia and myelodysplastic syndrome

Spectral karyotyping (SKY) was performed in patients with acute myeloid leukemia (AML; n = 25), secondary AML (s-AML; n = 7), myelodysplastic syndrome (MDS; n = 6) and s-MDS (n = 1) to complement conventional cytogenetic investigations. According to the results of conventional cytogenetics the patients were subdivided into three groups: group 1, normal karyotype, n = 19 cases, median age = 64 years; group 2, patients displaying either one or two single aberrations, n = 10 cases, median age = 54 years; group 3, patients with ⩾3 independent aberrations, n = 10 cases, median age = 61.5 years. SKY identified no abnormal metaphases in group 1. In one patient of group 2 a hidden translocation t(7;14)(q3?1;q2?2) could be revealed with SKY. Conventional cytogenetics had only shown trisomy 8. A similar t(7;14) was also detected in one patient of group 3. SKY was helpful for the delineation of marker chromosomes and additional material. Furthermore, SKY could distinguish between partial and total monosomies or real existing and apparent deletions. The combination of G-banding, FISH and SKY was found very useful for the precise delineation of the karyotype. As a result of our study we recommend SKY investigation as an important additional tool for accurate chromosome analysis. The detected t(7;14) might represent a novel recurrent translocation in acute myeloid leukemias.

Monitoring of donor chimerism in sorted CD34+ peripheral blood cells allows the sensitive detection of imminent relapse after allogeneic stem cell transplantation

Detection of impending relapse following allogeneic stem cell transplantation in cases of acute leukemia or myelodysplastic syndrome is desirable for planning treatment intervention. Genetic changes harbored by tumor cells are ideal for monitoring, but are not always available. Interestingly, analysis of serial donor chimerism in CD34+ cells sorted from blood may provide an alternative. Analysis of donor chimerism is an important diagnostic tool to assess the risk of relapse after allogeneic stem cell transplantation, especially in patients lacking a specific marker suitable for monitoring of minimal residual disease. We prospectively investigated the predictive value of donor chimerism analyses in sorted CD34+ peripheral blood cells in 90 patients with acute leukemia and myelodysplastic syndrome. The cumulative incidence of relapse after four years was significantly increased in cases with decreasing or incomplete CD34+ donor chimerism (57% vs. 18%, p=0.0001). Multivariate analysis confirmed decreasing CD34+ donor chimerism as an independent predictor of relapse and inferior survival. The interval between a decrease of CD34+ chimerism of less than 80% and hematologic relapse was 61 days (range 0–567). Monitoring of CD34+ donor chimerism in the peripheral blood allows prediction of imminent relapse after allogeneic stem cell transplantation even when a disease-specific marker is lacking.

Cytarabine Dose of 36 g/m2 Compared With 12 g/m2 Within First Consolidation in Acute Myeloid Leukemia: Results of Patients Enrolled Onto the Prospective Randomized AML96 Study

PURPOSE To assess the optimal cumulative dose of cytarabine for treatment of young adults with acute myeloid leukemia (AML) within a prospective multicenter treatment trial. PATIENTS AND METHODS Between 1996 and 2003, 933 patients (median age, 47 years; range 15 to 60 years) with untreated AML were randomly assigned at diagnosis to receive cytarabine within the first consolidation therapy at either a intermediate-dose of 12 g/m² (I-MAC) or a high-dose of 36 g/m² (H-MAC) combined with mitoxantrone. Autologous hematopoietic stem-cell transplantation or intermediate-dose cytarabine (10 g/m²) were offered as second consolidation. Patients with a matched donor could receive an allogeneic transplantation in a risk-adapted manner. RESULTS After double induction therapy including intermediate-dose cytarabine (10 g/m²), mitoxantrone, etoposide, and amsacrine, complete remission was achieved in 66% of patients. In the primary efficacy analysis population, a consolidation with either I-MAC or H-MAC did not result in significant differences in the 5-year overall (30% v 33%; P = .77) or disease-free survival (37% v 38%; P = .86) according to the intention-to-treat analysis. Besides a prolongation of neutropenia and higher transfusion demands in the H-MAC arm, rates of serious adverse events were comparable in the two groups. CONCLUSION In young adults with AML receiving intermediate-dose cytarabine induction, intensification of the cytarabine dose beyond 12 g/m² within first consolidation did not improve treatment outcome.

Concurrent JAK2(V617F) mutation and BCR-ABL translocation within committed myeloid progenitors in myelofibrosis

Concurrent JAK2(V617F) mutation and BCR-ABL translocation within committed myeloid progenitors in myelofibrosis