The EU-supported EuroFlow Consortium aimed at innovation and standardization of immunophenotyping for diagnosis and classification of hematological malignancies by introducing 8-color flow cytometry ...with fully standardized laboratory procedures and antibody panels in order to achieve maximally comparable results among different laboratories. This required the selection of optimal combinations of compatible fluorochromes and the design and evaluation of adequate standard operating procedures (SOPs) for instrument setup, fluorescence compensation and sample preparation. Additionally, we developed software tools for the evaluation of individual antibody reagents and antibody panels. Each section describes what has been evaluated experimentally versus adopted based on existing data and experience. Multicentric evaluation demonstrated high levels of reproducibility based on strict implementation of the EuroFlow SOPs and antibody panels. Overall, the 6 years of extensive collaborative experiments and the analysis of hundreds of cell samples of patients and healthy controls in the EuroFlow centers have provided for the first time laboratory protocols and software tools for fully standardized 8-color flow cytometric immunophenotyping of normal and malignant leukocytes in bone marrow and blood; this has yielded highly comparable data sets, which can be integrated in a single database.
Most modern treatment protocols for acute lymphoblastic leukaemia (ALL) include the analysis of minimal residual disease (MRD). To ensure comparable MRD results between different MRD-polymerase chain ...reaction (PCR) laboratories, standardization and quality control are essential. The European Study Group on MRD detection in ALL (ESG-MRD-ALL), consisting of 30 MRD-PCR laboratories worldwide, has developed guidelines for the interpretation of real-time quantitative PCR-based MRD data. The application of these guidelines ensures identical interpretation of MRD data between different laboratories of the same MRD-based clinical protocol. Furthermore, the ESG-MRD-ALL guidelines will facilitate the comparison of MRD data obtained in different treatment protocols, including those with new drugs.
Background
Amino acidopathies are a class of inborn errors of metabolism (IEM) that can be diagnosed by analysis of amino acids (AA) in plasma. Current strategies for AA analysis include cation ...exchange HPLC with post-column ninhydrin derivatization, GC-MS, and LC-MS/MS-related methods. Major drawbacks of the current methods are time-consuming procedures, derivative problems, problems with retention, and MS-sensitivity. The use of hydrophilic interaction liquid chromatography (HILIC) columns is an ideal separation mode for hydrophilic compounds like AA. Here we report a HILIC-method for analysis of 36 underivatized AA in plasma to detect defects in AA metabolism that overcomes the major drawbacks of other methods.
Methods
A rapid, sensitive, and specific method was developed for the analysis of AA in plasma without derivatization using HILIC coupled with tandem mass-spectrometry (Xevo TQ, Waters).
Results
Excellent separation of 36 AA (24 quantitative/12 qualitative) in plasma was achieved on an Acquity BEH Amide column (2.1×100 mm, 1.7 μm) in a single MS run of 18 min. Plasma of patients with a known IEM in AA metabolism was analyzed and all patients were correctly identified.
Conclusion
The reported method analyzes 36 AA in plasma within 18 min and provides baseline separation of isomeric AA such as leucine and isoleucine. No separation was obtained for isoleucine and allo-isoleucine. The method is applicable to study defects in AA metabolism in plasma.
Monitoring of minimal residual disease (MRD) has become routine clinical practice in frontline treatment of virtually all childhood acute lymphoblastic leukemia (ALL) and in many adult ALL patients. ...MRD diagnostics has proven to be the strongest prognostic factor, allowing for risk group assignment into different treatment arms, ranging from significant treatment reduction to mild or strong intensification. Also in relapsed ALL patients and patients undergoing stem cell transplantation, MRD diagnostics is guiding treatment decisions. This is also why the efficacy of innovative drugs, such as antibodies and small molecules, are currently being evaluated with MRD diagnostics within clinical trials. In fact, MRD measurements might well be used as a surrogate end point, thereby significantly shortening the follow-up. The MRD techniques need to be sensitive (≤10−4), broadly applicable, accurate, reliable, fast, and affordable. Thus far, flow cytometry and polymerase chain reaction (PCR) analysis of rearranged immunoglobulin and T-cell receptor genes (allele-specific oligonucleotide ASO-PCR) are claimed to meet these criteria, but classical flow cytometry does not reach a solid 10−4, whereas classical ASO-PCR is time-consuming and labor intensive. Therefore, 2 high-throughput technologies are being explored, ie, high-throughput sequencing and next-generation (multidimensional) flow cytometry, both evaluating millions of sequences or cells, respectively. Each of them has specific advantages and disadvantages.
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.
Abstract
Background
Triazole resistance is an increasing problem in invasive aspergillosis (IA). Small case series show mortality rates of 50%–100% in patients infected with a triazole-resistant ...Aspergillus fumigatus, but a direct comparison with triazole-susceptible IA is lacking.
Methods
A 5-year retrospective cohort study (2011–2015) was conducted to compare mortality in patients with voriconazole-susceptible and voriconazole-resistant IA. Aspergillus fumigatus culture-positive patients were investigated to identify patients with proven, probable, and putative IA. Clinical characteristics, day 42 and day 90 mortality, triazole-resistance profiles, and antifungal treatments were investigated.
Results
Of 196 patients with IA, 37 (19%) harbored a voriconazole-resistant infection. Hematological malignancy was the underlying disease in 103 (53%) patients, and 154 (79%) patients were started on voriconazole. Compared with voriconazole-susceptible cases, voriconazole resistance was associated with an increase in overall mortality of 21% on day 42 (49% vs 28%; P = .017) and 25% on day 90 (62% vs 37%; P = .0038). In non-intensive care unit patients, a 19% lower survival rate was observed in voriconazole-resistant cases at day 42 (P = .045). The mortality in patients who received appropriate initial voriconazole therapy was 24% compared with 47% in those who received inappropriate therapy (P = .016), despite switching to appropriate antifungal therapy after a median of 10 days.
Conclusions
Voriconazole resistance was associated with an excess overall mortality of 21% at day 42 and 25% at day 90 in patients with IA. A delay in the initiation of appropriate antifungal therapy was associated with increased overall mortality.
A multicenter, retrospective, cohort study showed a 21% higher day 42 mortality in voriconazole-resistant invasive aspergillosis compared with voriconazole-susceptible cases. In resistant cases, switch to appropriate antifungal therapy was associated with increased mortality compared with patients who directly received appropriate antifungal therapy.
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.
MicroRNAs (miRNAs) control the expression of protein-coding genes in normal hematopoietic cells and, consequently, aberrant expression may contribute to leukemogenesis. To identify miRNAs relevant to ...pediatric acute lymphoblastic leukemia (ALL), we cloned 105 known and 8 new miRNA genes expressed in patients' leukemia cells. Instead of known miRNA genes, new miRNA genes were not evolutionarily conserved. Quantification of 19 selected miRNA genes revealed an aberrant expression in ALL as compared with normal CD34+ cells (P <or= 0.02); both upregulated (14/19) and downregulated (5/19) expressions were observed. Eight miRNAs were differentially expressed between MLL and non-MLL precursor B-ALL cases (P<0.05). Most remarkably, miR-708 was 250- up to 6500-fold higher expressed in 57 TEL-AML1, BCR-ABL, E2A-PBX1, hyperdiploid and B-other cases than in 20 MLL-rearranged and 15 T-ALL cases (0.0001<P<0.01), whereas the expression of miR-196b was 500-fold higher in MLL-rearranged and 800-fold higher in 5 of 15 T-ALL cases as compared with the expression level in the remaining precursor B-ALL cases (P<0.001). The expression did not correlate with the maturation status of leukemia cells based on immunoglobulin and T-cell receptor rearrangements, immunophenotype or MLL-fusion partner. In conclusion, we identified new miRNA genes and showed that miRNA expression profiles are ALL subtype-specific rather than linked to the differentiation stadium associated with these subtypes.
Detection of minimal residual disease (MRD) has proven to provide independent prognostic information for treatment stratification in several types of leukemias such as childhood acute lymphoblastic ...leukemia (ALL), chronic myeloid leukemia (CML) and acute promyelocytic leukemia. This report focuses on the accurate quantitative measurement of fusion gene (FG) transcripts as can be applied in 35-45% of ALL and acute myeloid leukemia, and in more than 90% of CML. A total of 26 European university laboratories from 10 countries have collaborated to establish a standardized protocol for TaqMan-based real-time quantitative PCR (RQ-PCR) analysis of the main leukemia-associated FGs within the Europe Against Cancer (EAC) program. Four phases were scheduled: (1) training, (2) optimization, (3) sensitivity testing and (4) patient sample testing. During our program, three quality control rounds on a large series of coded RNA samples were performed including a balanced randomized assay, which enabled final validation of the EAC primer and probe sets. The expression level of the nine major FG transcripts in a large series of stored diagnostic leukemia samples (n=278) was evaluated. After normalization, no statistically significant difference in expression level was observed between bone marrow and peripheral blood on paired samples at diagnosis. However, RQ-PCR revealed marked differences in FG expression between transcripts in leukemic samples at diagnosis that could account for differential assay sensitivity. The development of standardized protocols for RQ-PCR analysis of FG transcripts provides a milestone for molecular determination of MRD levels. This is likely to prove invaluable to the management of patients entered into multicenter therapeutic trials.
Most consensus leukemia & lymphoma antibody panels consist of lists of markers based on expert opinions, but they have not been validated. Here we present the validated EuroFlow 8-color antibody ...panels for immunophenotyping of hematological malignancies. The single-tube screening panels and multi-tube classification panels fit into the EuroFlow diagnostic algorithm with entries defined by clinical and laboratory parameters. The panels were constructed in 2-7 sequential design-evaluation-redesign rounds, using novel Infinicyt software tools for multivariate data analysis. Two groups of markers are combined in each 8-color tube: (i) backbone markers to identify distinct cell populations in a sample, and (ii) markers for characterization of specific cell populations. In multi-tube panels, the backbone markers were optimally placed at the same fluorochrome position in every tube, to provide identical multidimensional localization of the target cell population(s). The characterization markers were positioned according to the diagnostic utility of the combined markers. Each proposed antibody combination was tested against reference databases of normal and malignant cells from healthy subjects and WHO-based disease entities, respectively. The EuroFlow studies resulted in validated and flexible 8-color antibody panels for multidimensional identification and characterization of normal and aberrant cells, optimally suited for immunophenotypic screening and classification of hematological malignancies.
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