Adult precursor B-ALL with BCR/ABL gene rearrangements displays a unique immunophenotype based on the pattern of CD10, CD34, CD13 and CD38 expresssion

A review of immunotargeted therapy for Philadelphia chromosome positive acute lymphoblastic leukaemia: making progress in chemotherapy-free regimens

Philadelphia chromosome-positive acute lymphoblastic leukemia (PH + ALL) is the most common cytogenetic abnormality of B-ALL in adults and is associated with poor prognosis. Previously, the only curative treatment option in PH + ALL was allogeneic hematopoietic stem cell transplantation (Allo-HSCT). Since 2000, targeted therapy combined with chemotherapy, represented by the tyrosine kinase inhibitor Imatinib, has become the first-line treatment for PH + ALL. Currently, the remission rate and survival rate of Imatinib are superior to those of simple chemotherapy, and it can also improve the efficacy of transplantation. More recently, some innovative immune-targeted therapy greatly improved the prognosis of PH + ALL, such as Blinatumomab and Inotuzumab Ozogamicin. For patients with ABL1 mutations and those who have relapsed or are refractory to other treatments, targeted oral small molecule drugs, monoclonal antibodies, Bispecific T cell Engagers (BiTE), and chimeric antigen receptor (CAR) T cells immunotherapy are emerging as potential treatment options. These new therapeutic interventions are changing the treatment landscape for PH + ALL. In summary, this review discusses the current advancements in targeted therapeutic agents shift in the treatment strategy of PH + ALL towards using more tolerable chemotherapy-free induction and consolidation regimens confers better disease outcomes and might obviate the need for HSCT.

Immunophenotypic Characteristics and Cytogenetic Analysis of Adolescent and Young Adult B-Cell Acute Lymphoblastic Leukemia: Correlations With Clinicopathological Parameters

Introduction Acute lymphoblastic leukemia (ALL) has suboptimal survival rates for adolescents and young adults (AYA) as compared to children. Very limited studies have been conducted on AYA patients in India. This study aimed to identify the cytogenetic and immunophenotype characteristics of B-cell ALL (B-ALL) in AYA patients and determine its correlation with clinicopathological parameters in the Southern India region. Method The study was a prospective study conducted for three years, from June 2019 to May 2022, in India. Newly diagnosed 90 patients with AYA (13-40 years) ALL were recruited. A B-ALL diagnosis was made based on morphology with cytochemical stains and immunophenotype by flow cytometry (FCM). Cytogenetic analysis was also performed using karyotyping and fluorescent in situ hybridization to identify chromosomal aberrations. The cytogenetics results were correlated with immunophenotyping and clinicopathological characteristics. Variables were analyzed using the Mann-Whitney U test and Chi-square test using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, NY, USA). Results The mean age was 22.68 ± 8.06 years. It was observed that the most common structural chromosomal abnormality for AYA was t(9;22) in 14 (15%) cases, followed by 6q deletions in seven (8%) cases, t(1;19) in four (4%) cases, and t(12;17) and t(6;14) in two (2%) cases each. In addition, t(3;12), t(2;11), t(12;21), t(1;9), t(2;12), and t(X;10) were found in one (1%) case each. The most common numerical abnormality was hyperdiploidy (15; 17%), followed by hypodiploidy (10; 11%). Further, myeloid antigen expression of CD33 was the most common aberrantly expressed marker found in 20 (28%) cases, followed by CD15 in three cases (5%), CD13 in three (4%) cases, and CD11b in two (3%) cases. It was also observed that in Ph+ve cases, CD33 and CD13 were most commonly expressed in three (33%) and two (17%) cases, respectively. In contrast, in Ph-ve patients, their expressions were lesser at 17 (27%) and one (2%) cases, respectively. In addition, leukemia-associated immunophenotype pattern (LAIP) markers CD44 6 (86%) and CD123 5 (55%) were also found to be significantly associated with Ph+ve, whereas their values in the Ph-ve group were lesser at 25 (42%) and 9 (17%), respectively. Our data also showed that older age wassignificantly associated with Ph+ve with a median age of 30 years (p = 0.012). In comparison, the median age of Ph-ve was only 21 years. Conclusion Our study established that the incidence of cytogenetic abnormalities for AYA was consistent with previously reported data. This study reaffirms that Ph+ve cases have significant associations with MyAg (CD13), LAIP (CD123 and CD44), and older age for the South Indian population.

Commonly Assessed Markers in Childhood BCP-ALL Diagnostic Panels and Their Association with Genetic Aberrations and Outcome Prediction

Immunophenotypic characterization of leukemic cells with the use of flow cytometry (FC) is a fundamental tool in acute lymphoblastic leukemia (ALL) diagnostics. A variety of genetic aberrations underlie specific B-cell precursor ALL (BCP-ALL) subtypes and their identification is of great importance for risk group stratification. These aberrations include: ETV6::RUNX1 fusion gene, Philadelphia chromosome (BCR::ABL1 fusion gene), rearrangements of the KMT2A, TCF3::PBX1 fusion gene and changes in chromosome number (hyperdiploidy and hypodiploidy). Diagnostic panels for BCP-ALL usually include B-cell lineage specific antigens: CD19, CD10, CD20, maturation stage markers: CD34, CD10, CD38, TdT, IgM and other markers useful for possible genetic subtype indication. Some genetic features of leukemic cells (blasts) are associated with expression of certain antigens. This review comprehensively summarizes all known research data on genotype-immunophenotype correlations in BCP-ALL. In some cases, single molecules are predictive of particular genetic subtypes, i.e., NG2 with KMT2A gene rearrangements or CD123 with hyperdiploidy. However, much more information on possible genotype or prognosis can be obtained with wider (≥8-color) panels. In several studies, a quantitative antigen expression scale and advanced statistical analyses were used to further increase the specificity and sensitivity of genotype/immunophenotype correlation detection. Fast detection of possible genotype/immunophenotype correlations makes multicolor flow cytometry an essential tool for initial leukemia diagnostics and stratification.

Immunophenotypic characteristics of ZNF384 rearrangement compared with BCR-ABL1, KMT2A rearrangement, and other adult B-cell precursor acute lymphoblastic leukemia

BACKGROUND

ZNF384 rearrangement has been recently identified as a new subtype of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, comprehensive studies clarifying immunophenotypic features and discriminating them from non-ZNF384 in adult BCP-ALL remain scarce to date.

METHODS

Flow cytometric assessments were retrospectively performed in 43 patients with ZNF384 rearrangement, 45 with BCR-ABL1, 29 with KMT2A rearrangement and 44 with other BCP-ALL in the analysis cohort.

RESULTS

CD33- and CD13-positive frequencies were significantly higher in patients with ZNF384 rearrangement than in those with non-ZNF384; however, no significant difference was observed in CD10- and CD123-positive frequencies. Analysis of antigen-positive cell proportion and median fluorescence intensity (MFI) further indicated that patients with ZNF384 rearrangement had significantly lower CD10 and higher CD33, CD13, and CD123 proportion and MFI. However, compared with KMT2A rearrangement, the CD10 expression in patients with ZNF384 rearrangement was higher, with the median percentage and MFI of 36.16 (3.63-94.79)% versus 4.53 (0.03-21.00)%, and 4.50 (0.86-32.26) versus 2.06 (0.87-4.04), respectively (p < 0.0001). Furthermore, compared with BCR-ABL1 and other BCP-ALL, ZNF384 rearrangement had significantly higher CD33 and CD13 proportion and MFI (p < 0.0001 and p < 0.05, respectively). In addition, higher CD123 proportion and MFI in ZNF384 rearrangement than those in the other three groups were reported for the first time (p < 0.01). A flow cytometry scoring system, including CD10%, CD33MFI, CD13%, and CD123MFI, was proposed and verified to predict ZNF384 rearrangement with high sensitivity and specificity, that is, 76.74% and 91.53% in the analysis and 87.50% and 91.30% in the validation cohort.

CONCLUSIONS

The multiparameter immunophenotypic scoring system could suggest ZNF384 rearrangement.

Bcr-Abl drives the formation of Hsp70/Bim PPI to stabilize oncogenic clients and prevent cells from undergoing apoptosis

Although tyrosine kinase inhibitors that inhibit Bcr-Abl kinase activity have shown excellent efficacy in the clinical application of CML patients, it still a challenge to discover alternative targets and novel therapies because of the emergence of Bcr-Abl-independent resistance. Most recently, Hsp70/Bim complex was revealed that driven by Bcr-Abl and testified as a specific target for CML because it folds and stabilizes many Hsp70 oncogenic substrates that mediate CML specific signaling pathways. However, the relationship between Bcr-Abl and Hsp70/Bim complex and how the chaperone complex contributes to Bcr-Abl-driven leukemogenic cells remain unclear. Herein, with the help of S1g-2, a specific small-molecule inhibitor of Hsp70/Bim complex, and Bcr-Abl knockdown to induce a panel of cancer cell lines apoptosis, we illustrated that Bcr-Abl could prevent cells from undergoing apoptosis mainly by driving the formation of Hsp70/Bim complex both in Bcr-Abl positive CML cells and ALL cells. Through cell-based Co-immunoprecipitation experiments, we identified that Bcr-Abl could stabilize oncogenic clients including AKT and eIF4E mainly by driving the formation of Hsp70/Bim complex in Bcr-Abl positive cells. Moreover, we identified that Bim mediates interactions of Hsp70 and Bak in Bcr-Abl positive cells. Together, the target identification of Hsp70/Bim complex could make it as a promising anticancer target for Bcr-Abl positive leukemia treatment.

Updating recommendations of the Brazilian Group of Flow Cytometry (GBCFLUX) for diagnosis of acute leukemias using four-color flow cytometry panels

INTRODUCTION

Flow cytometry has become an increasingly important tool in the clinical laboratory for the diagnosis and monitoring of many hematopoietic neoplasms. This method is ideal for immunophenotypic identification of cellular subpopulations in complex samples, such as bone marrow and peripheral blood. In general, 4-color panels appear to be adequate, depending on the assay. In acute leukemias (ALs), it is necessary identify and characterize the population of abnormal cells in order to recognize the compromised lineage and classify leukemia according to the WHO criteria. Although the use of eight- to ten-color immunophenotyping panels is wellestablished, many laboratories do not have access to this technology.

OBJECTIVE AND METHOD

In 2015, the Brazilian Group of Flow Cytometry (Grupo Brasileiro de Citometria de Fluxo, GBCFLUX) proposed antibody panels designed to allow the precise diagnosis and characterization of AL within available resources. As many Brazilian flow cytometry laboratories use four-color immunophenotyping, the GBCFLUX has updated that document, according to current leukemia knowledge and after a forum of discussion and validation of antibody panels.

RESULTS

Recommendations for morphological analysis of bone marrow smears and performing screening panel for lineage (s) identification of AL were maintained from the previous publication. The lineage-oriented proposed panels for B and T cell acute lymphoblastic leukemia (ALL) and for acute myeloid leukemia (AML) were constructed for an appropriate leukemia classification.

CONCLUSION

Three levels of recommendations (i.e., mandatory, recommended, and optional) were established to enable an accurate diagnosis with some flexibility, considering local laboratory resources and patient-specific needs.

Plasma Neprilysin Displays No Relevant Association With Neurohumoral Activation in Chronic HFrEF

Background

Neprilysin is a transmembrane endopeptidase involved in the breakdown of a variety of vasoactive peptides and serves as a therapeutic target in heart failure with reduced ejection fraction (HFrEF). This study aimed to investigate the relationship of circulating neprilysin with neurohumoral activation and the impact of plasma neprilysin activity on prognosis in HFrEF.

Methods and Results

A total of 369 chronic HFrEF patients were enrolled prospectively. Plasma neprilysin concentration and activity were determined by a specific ELISA and a fluorometric method. The association between plasma neprilysin and heart failure (HF) severity, neurohumoral activation, ie norepinephrine and absolute renin concentration, as well as all‐cause mortality was assessed. Median plasma neprilysin concentrations and activity levels were 413 pg/mL (interquartile range 0–4111) and 2.36 nmol/mL per minute (interquartile range 1.16–4.59). No correlation could be shown between plasma neprilysin concentrations and activity (r_s=0.09, P=0.088). Plasma neprilysin activity correlated with HF severity reflected by New York Heart Association stage (P=0.003) and tertiles of N‐terminal pro‐B‐type natriuretic peptide (P<0.001), whereas neprilysin concentrations did not (P=0.220; P=0.849). There was no relevant relationship between plasma neprilysin concentrations and activity, with neurohumoral activation reflected by absolute renin concentration (r_s=−0.02, P=0.648; r_s=0.03, P=0.574) or norepinephrine levels (r_s=−0.06, P=0.248; r_s=0.20, P<0.001). Neither circulating neprilysin concentrations nor activity were associated with outcome.

Conclusions

Plasma neprilysin concentrations and activity are not directly related to neurohumoral activation, indicating that neprilysin regulation is either more complex or not correctly mirrored by circulating neprilysin as a biomarker. Circulating neprilysin concentrations and activity were not associated with overall survival, implicating limited prognostic value of plasma neprilysin measurements in HFrEF patients.

Clinical Impact of CD25/CD123 Coexpression in Adult B-Cell Acute Lymphoblastic Leukemia Patients

This study aimed to determine the clinical impact of CD25⁺/CD123⁺ coexpression in adult B-cell acute lymphoblastic leukemia (B-ALL) cases. One hundred and twenty newly diagnosed B-ALL patients (≤60 years old) were included in this study. CD123 and CD25 expression on leukemic blast cells were assessed using flow cytometry. CD25⁺/CD123⁺ coexpression was detected in 40/120 B-ALL patients (33.3%). All B-ALL patients showed CD25⁺/CD123⁺ coexpression had lower induction of remission response and shorter overall survival as compared to B-ALL cases lacking coexpression. In conclusion, CD25⁺/CD123⁺ positive coexpression is a reliable flow cytometry marker for prediction of the outcome of adult B-ALL patients and could be used as a novel parameter for risk stratification of adult B-ALL cases.

Poor Prognosis Biomolecular Factors Are Highly Frequent in Childhood Acute Leukemias From Oaxaca, Mexico

OBJECTIVE

To investigate the cellular and molecular epidemiology of acute leukemias in vulnerable populations of children and adolescents in Oaxaca de Juarez, Mexico.

MATERIAL AND METHODS

Descriptive, cross-sectional and retrospective study, conducted from 2014 to 2018 in which profiles of molecular and immunophenotypic aberrations were investigated in children and adolescents diagnosed with acute leukemia, by evaluating 28 molecular abnormalities by HemaVision-Q28 multiplex RT-PCR kit and standardized EuroFlow Immunophenotyping of bone marrow cells.

RESULTS

We included 218 patients, with 82.5% younger than 14 years and 17.5% adolescents. The median age was 9 years and a main peak of incidence was recorded at age of 4 to 5 years. B-cell acute lymphoblastic leukemia was diagnosed in 70.64% of all cases, acute myeloid leukemia was in 22.48%, T-cell acute lymphoblastic leukemia in 6.42%, and mixed lineage acute leukemia in 0.46% of cases. Overall, chromosomal translocations were positive in 29.82% of cases. While 65.31% of patients with acute myeloid leukemia reported aberrancies, only in 18.83% of B-cell acute lymphoblastic leukemia cases genetic abnormalities were obvious. Surprisingly, most prevalent translocations in B-cell acute lymphoblastic leukemia were t(9;22) in 20.7%, followed by t(4;11) in 17.2% and t(6;11) in 13.8%, whereas patients with acute myeloid leukemia showed t(15;17) in 40.6% and t(8;21) in 21.9%. In contrast, an homogeneous expression of t(3;21) and t(6;11) was recorded for T-cell acute lymphoblastic leukemia and mixed lineage acute leukemia cases, respectively. Except for t(1;19), expressed only by pre-B cells, there was no association of any of the studied translocations with differentiation stages of the B-leukemic developmental pathway.

CONCLUSION

Our findings identify near 50% of patients with acute lymphoblastic leukemia at debut with high-risk translocations and poor prognosis in B-cell acute lymphoblastic leukemia as well as an unexpected increase of acute myeloid leukemia cases in young children, suggesting a molecular shift that support a higher incidence of poor prognosis cases in Oaxaca.

Spectrum and Immunophenotypic Profile of Acute Leukemia: A Tertiary Center Flow Cytometry Experience

BACKGROUND

For diagnosis, sub-categorization and follow up of Acute Leukemia (AL), phenotypic analysis using flow cytometry is mandatory.

MATERIAL AND METHODS

We retrospectively analyzed immunophenotypic data along with cytogenetics/molecular genetics data (wherever available) from 631 consecutive cases of AL diagnosed at our flow cytometry laboratory from January 2014 to August 2017.

RESULTS

Of the total 631 cases, 52.9% (n=334) were acute lymphoblastic leukemia (ALL), 43.9% (n=277) acute myeloid leukemia (AML), 2.2% (n=14) mixed phenotypic acute leukemia (MPAL), 0.5% (n=3) acute undifferentiated leukemia (AUL) and 0.5% (n=3) chronic myeloid leukemia in blast crisis (CML-BC). ALL cases comprised of 81.7% (n=273/334) B-cell ALLs (95.2%, n=260/273 common B-ALLs and 4.8%, n=13/273 Pro B-ALLs). CD13 was the commonest cross lineage antigen, expressed in B-ALL (25.6%, n=70/273), followed by CD33 (17.9%, n=49) and combined CD13/CD33 (11.3%, n=31/273) expression. T-ALLs constituted 18.3% (n=61/334) of total ALLs and included 27.9% (n=17/61) cortical T- ALLs. CD13 was commonest (32.7%, n=20/61) aberrantly expressed antigen in T-ALLs, followed by CD117 (19.1%, n=9/47). AML cases included 32.1% (n=89/277) AML with recurrent genetic abnormalities, 9.0% (n=25/277) with FLT3/NPM1c mutation and 58.9% (n=163/277) AML NOS including 14.7% (n=24/163) AML M4/M5, 1.8% (n=3/163) AML M6 and 3.7% (n=6/163) AML M7. In AMLs, CD19 aberrancy was the most common (20.2%, n=56/277) followed by CD56 (15.8%, n=42/265).

CONCLUSIONS

In this study, we document the spectrum, correlate the immunophenotype with genetic data of all leukemias, especially concerning T-ALL where the data from India is scarce.

Daratumumab binds to mobilized CD34+ cells of myeloma patients in vitro without cytotoxicity or impaired progenitor cell growth

Background

The monoclonal antibody daratumumab, approved for treating myeloma, targets CD38, a protein on myeloma and also on CD34+ hematopoietic progenitor cells. Because mobilized CD34+ cells are critical for stem cell transplant, we investigated the in vitro activity of daratumumab on mobilized CD34+ cells from myeloma patients with no prior exposure to daratumumab.

Methods

We determined the number of CD38 molecules per CD34+ cell, and whether daratumumab bound to CD34+ cells, whether C1q bound to daratumumab-coated CD34+ cells and whether daratumumab-related complement-dependent cytotoxicity (CDC) occurred. We also examined CD34+ cell progenitor cell colony capacity in assays with pre-plating incubation of CD34+ cells with daratumumab alone or with daratumumab and the CD59 inhibitory antibody BRIC229, and also assessed CD34+ cell responses to increasing doses of daratumumab in caspase 3/7 activity assays.

Results

Although 75% of mobilized CD34+ cells co-express CD38, CD38 was minimally present on CD34+ cells compared to Daudi and KG-1 controls, C1q did not bind to daratumumab-coated CD34+ cells, and CDC did not occur. CD34+ cells incubated in complement-rich human serum with daratumumab alone or with daratumumab and BRIC229, and then plated in progenitor cell assays, produced similar numbers of colonies as controls. In progenitor cell assays with cryopreserved or fresh unselected or CD34-selected cells, daratumumab did not affect progenitor cell capacity, and in caspase 3/7 activity assays CD34+ cells were not affected by increasing doses of daratumumab.

Conclusion

In vitro, daratumumab is not toxic to mobilized CD34+ progenitor cells from myeloma patients.

The immunophenotypic characteristics and flow cytometric scoring system of acute myeloid leukemia with t(8;21) (q22;q22); RUNX1-RUNX1T1

INTRODUCTION

The translocation t(8;21) is one of the most frequent chromosome translocations in AML. Molecular (cyto)genetics is regarded as the gold standard for diagnosis. However, due to the complicated variety of AML-related genetic abnormalities, comprehensive screening for all of these abnormalities may not be cost-effective. Therefore, a flow cytometric (FC) scoring system was generated in this study for rapid screening and diagnosis of t(8;21)AML.

METHODS

The immunophenotypic characteristics of leukemic cells and neutrophils in cases with t(8;21) AML or other subtypes of AML were analyzed to find a method for the flow diagnosis of t(8;21) AML.

RESULTS

In this study, we picked six FC features pointing to the diagnosis of t(8;21) AML: The blasts show high-intensity expression of CD34; aberrant expression of CD19, cCD79a, and CD56 in myeloblasts; co-expression of CD56 in neutrophils, especially in immature neutrophils; and a maturity disturbance in granulocytes. A six-point score was devised using these features. By ROC analysis, the AUC was 0.952, and the sensitivity, specificity, PPV, and NPV were 0.86, 0.90. 0.91, and 0.84 when the score was ≥3 points. The score was then prospectively validated on an independent cohort, and the AUC of the ROC curve for the validation cohort was 0.975. When the cutoff value was set at 3, the obtained sensitivity and specificity values were 0.91 and 0.94, respectively.

CONCLUSIONS

The FC score described can be used for the identification and rapid screening of t(8;21) AML.

Primary testicular Ph-positive B lymphoblastic lymphoma: an unusual presentation and review

Primary testicular B-lymphoblastic lymphoma is a rare entity. Primary testicular Ph-positive B lymphoblastic lymphoma was not reported before. We reported a 27-year-old man with primary testicular Ph-positive B lymphoblastic lymphoma, for which fluorescent in-situ hybridization (FISH) for the Philadelphia chromosome was not performed at the initial hospitalization. The patient showed manifestation of Ph-positive acute lymphoblastic leukemia at relapse. In this report, we reviewed the current literature about primary testicular B-lymphoblastic lymphoma, Ph-positive lymphoma and Ph-positive clone evolution. This report has 3 meanings. First: This is first report on primary testicular Ph-positive B lymphoblastic lymphoma. Second: This shows the importance of cytogenics for lymphoma treatment. Third: This implies Philadelphia-positive subclone evolution.

B-acute lymphoblastic leukemia/lymphoblastic lymphoma

OBJECTIVES

This session of the 2013 Society of Hematopathology/European Association for Haematopathology Workshop was dedicated to B-acute lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (LBL) with recurrent translocations and not otherwise specified.

METHODS

In this review, we summarize the cases discussed during the workshop, review the pertinent and most recent literature on the respective topics, and provide a few key points that may aid in the workup of patients with B-ALL/LBL.

RESULTS

Many of the submitted cases showed interesting diagnostic, immunophenotypic, or clinical aspects of B-ALL with BCR/ABL1, MLL-associated, and other recurrent chromosomal abnormalities. Several cases showed rare aberrancies such as coexistent IGH/BCL2 and MYC rearrangements and raised issues in classification. Other cases had unusual clinical presentations, including B-ALL with hypereosinophilia and therapy-related B-ALL. Several cases highlighted the role of flow cytometry immunophenotyping in distinguishing benign B-cell precursors from aberrant lymphoblasts, and other cases raised questions regarding the clinical importance of myeloperoxidase positivity in acute lymphoblastic leukemia.

CONCLUSIONS

The complexity and spectrum of cases presented in this review highlight the importance of clinicopathologic correlation and the value of ancillary studies in the classification and workup of patients with B-ALL/LBL.

Advances and issues in flow cytometric detection of immunophenotypic changes and genomic rearrangements in acute pediatric leukemia

Flow cytometry with its rapidly increasing applications has been using to aid the diagnosis of hematological disorders for more than two decades. It is also the most commonly used technology in childhood leukaemia diagnosis, characterization, prognosis prediction and even in the decision making of targeted therapy. Leukemia cells can be recognized by virtue of unique cell marker combinations, visualized with monoclonal antibodies conjugated and detected by flow cytometry. Currently, such instruments allow the detection of eight or more markers by providing a comprehensive description of the leukemic cell phenotype to facilitate their identification, especially in detecting and monitoring of minimal residual disease (MRD) during treatment. Additionally, the flow cytometric DNA index (DI) can identify biclonality at diagnosis and distinguish persistent aneuploid leukemia during induction therapy, when the standard cytogenetic and morphologic techniques fail to do so. This review focuses on the latest advances and application issues about some of flow cytometric diagnostic and prognostic applications for acute pediatric leukemia.

Current and future management of Ph/BCR-ABL positive ALL

Following the introduction of targeted therapy with tyrosine kinase inhibitors (TKI) at the beginning of the past decade, the outcome of patients with Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) has dramatically improved. Presently, the use of refined programs with first/second generation TKI's and chemotherapy together with allogeneic stem cell transplantation allow up to 50% of all patients to be cured. Further progress is expected with the new TKI ponatinib, overcoming resistance caused by T315I point mutation, other targeted therapies, autologous transplantation in molecularly negative patients, therapeutic monoclonal antibodies like inotuzumab ozogamicin and blinatumomab, and chimeric antigen receptor-modified T cells. Ph+ ALL could become curable in the near future even without allogeneic stem cell transplantation, minimizing the risk of therapy-related death and improving greatly the quality of patients' life.

Acute Leukemia Subclassification: A Marker Protein Expression Perspective

Improved leukemia classification and tailoring of therapy have greatly improved patient outcome particularly for children with acute leukemia (AL). Using immunophenotyping, molecular genetics and cytogenetics the low hanging fruits of biomedical research have been successfully incorporated in routine diagnosis of leukemia subclasses. Future improvements in the classification and understanding of leukemia biology will very likely be more slow and laborious. Recently, gene expression profiling has provided a framework for the global molecular analysis of hematological cancers, and high throughput proteomic analysis of leukemia samples is on the way. Here we consider classification of acute leukemia samples by flow cytometry using the marker proteins of immunophenotyping as a component of the proteome. Marker protein expressions are converted into quantitative expression values and subjected to computational analysis. Quantitative multivariate analysis from panels of marker proteins has demonstrated that marker protein expression profiles can distinguish MLLre from non-MLLre ALL cases and also allow to specifically distinguish MLL/AF4 cases. Potentially, these quantitative expression analyses can be used in clinical diagnosis. Immunophenotypic data collection using flow cytometry is a fast and relatively easily accessible technology that has already been implemented in most centers for leukemia diagnosis and the translation into quantitative expression data sets is a matter of flow cytometer settings and output calibration. However, before application in clinical diagnostics can occur it is crucial that quantitative immunophenotypic data set analysis is validated in independent experiments and in large data sets.

EuroFlow antibody panels for standardized n-dimensional flow cytometric immunophenotyping of normal, reactive and malignant leukocytes

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.

Prognostic significance of immunophenotypic and karyotypic features of Philadelphia positive B-lymphoblastic leukemia in the era of tyrosine kinase inhibitors

BACKGROUND

Philadelphia chromosome (Ph)-positive B-lymphoblastic leukemia exhibits immunophenotypic, karyotypic, and molecular genetic heterogeneity. The prognostic significance of these parameters was assessed in the context of intensive tyrosine kinase inhibitor (TKI)-based chemotherapy.

METHODS

The authors studied 65 adult patients with Ph-positive acute lymphoblastic leukemia (ALL) who received treatment with TKI-based therapy, correlated their clinicopathologic heterogeneity with patient outcome, and compared the findings with those from 60 adult patients with diploid B-cell ALL who received similar chemotherapy without a TKI.

RESULTS

Ph-positive ALL was associated with older age (P = .01), the common-B immunophenotype characterized by a greater frequency of CD13 (alanine aminopeptidase) coexpression (P = .004), CD66c (carcinoembryonic antigen-related cell adhesion molecule 3) expression (P = .007), and CD25 (interleukin-2 receptor alpha chain) expression (P < .001) and with a lower frequency of CD15 (3-fucosyl-N-acetyl-lactosamine) expression (P < .001). Conventional karyotypic analyses indicated that the Ph chromosome was the sole abnormality in 19 patients (30%), was present with other aberrancies in 43 patients (65%), and was absent (detectable only by fluorescence in situ hybridization [FISH] or quantitative reverse transcriptase-polymerase chain reaction [RT-PCR] analysis) in 3 patients (5%). The presence of the breakpoint cluster region-v-Abelson murine leukemia viral oncogene homolog fusion gene (BCR-ABL) was confirmed in all patients by FISH or RT-PCR (the 190-kDa protein [p190] construct was present in 49 patients [77%], and the p210 fusion transcript construct was present in 15 patients [23%]). The presence of a supernumerary Ph chromosome was correlated with a higher incidence of CD20 (B-lymphocyte antigen, nonglycosylated phosphoprotein) expression (P < .001), whereas the p210 construct was correlated with aberrant CD25 expression (P = .05). Outcomes were not influenced by the degree of karyotypic complexity (including the presence or absence of a supernumerary Ph chromosome), CD20 expression, or myeloid antigen expression (CD13, CD33 [myeloid lineage transmembrane receptor], CD66c). CD25 expression was associated with inferior survival in univariate analysis (P = .051) but not in multivariate analysis (P = .092).

CONCLUSIONS

In the context of intensive, TKI-based chemotherapy, the immunophenotypic, karyotypic, and molecular heterogeneity of Ph-positive ALL no longer influences outcome.

Flow cytometric study of potential target antigens (CD19, CD20, CD22, CD33) for antibody-based immunotherapy in acute lymphoblastic leukemia: analysis of 552 cases

Monoclonal antibody (MoAb)-based therapies have opened innovative treatment avenues that have impacted on the management of patients with both neoplastic and non-neoplastic hematological diseases. The aim of our study was to evaluate in a large series of cases of acute lymphoblastic leukemia (ALL) the expression of specific antigens, CD19, CD20, CD22, and CD33, for which MoAbs are available for clinical use. For each antigen, evaluation was based on the percentage of positive leukemic cells and the degree of antigen expression by mean fluorescence intensity (MFI) and antibody binding capacity (ABC) that were correlated with age, immunophenotype, and presence/absence of particular molecular markers. We can document that some of the analyzed antigens showed a degree of expression related to the B-cell maturation profile, and that the antigen expression intensity appeared to vary according to the presence of specific genetic markers. These findings suggest that the possible clinical use of a given MoAb in patients with ALL should take into account both the maturation profile of the leukemic cells and the presence of a given molecular transcript. Only clinical studies will conclusively demonstrate whether the differences in antigenic expression truly correlate with the different therapeutic efficacies of the various clinical grade MoAbs.

Surrogate marker profiles for genetic lesions in acute leukemias

The basic hypothesis of surrogate marker profiles is that individual genetic lesions result in characteristic distortions of the cellular phenotype with some predictable consistency that can be exploited by sophisticated immunophenotyping. While cytogenetic and molecular aberrancies currently are accepted prognostic predictors in acute leukemias, single antigen expression and even antigenic profiles rarely impact on prognosis. However, increasingly, phenotypes are delineated which can serve as surrogates for underlying genetic aberrations of clinical importance. This development is of particular significance as antileukemic therapy becomes available that targets any component of the disturbed molecular pathways associated with these genetic lesions. This chapter will focus on established surrogate marker profiles, such as those for PML/RARα, AML1/ETO, FLT3-gene mutated acute lymphocytic leukemia (ALL), and BCR/ABL(POS) ALL. As the list of therapeutic targets grows, the role of surrogate antigen profiles will grow, as they can predict for the efficacy of targeted approaches in lieu of expensive, time-consuming and not always accessible genetic analyses.

A unique complex translocation involving six different chromosomes in a case of childhood acute lymphoblastic leukemia with the Philadelphia chromosome and adverse prognosis

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Approximately 84% of cases of ALL are classified as B-precursor ALL, 14% of cases are T-cell and 2% of cases are B-cell (B-)ALL. About one third of B-ALL cases show an abnormal karyotype. Combining data obtained by immunophenotyping, karyotyping and molecular cytogenetic analyses allows for a better understanding of this heterogeneous disease. This study reports an exceptional B-ALL case with a poor prognosis and unique complex chromosomal aberrations not previously observed, i.e., a translocation involving the six chromosomal regions 1q42, 4q21, 4q24, 4q35 (twice), 8q22 and 10p15.3 besides 9q34 and 22q11.2.

Flow minimal residual disease monitoring of candidate leukemic stem cells defined by the immunophenotype, CD34+CD38lowCD19+ in B-lineage childhood acute lymphoblastic leukemia

Flow cytometric minimal residual disease (MRD) monitoring could become more powerful if directed towards the disease-maintaining leukemic stem cell (LSC) compartment. Using a cohort of 48 children with B-lineage acute lymphoblastic leukemia (ALL), we sought the newly proposed candidate-LSC population, CD34(+)CD38(low)CD19(+), at presentation and in end of induction bone marrow samples. We identified the candidate LSC population in 60% of diagnostic samples and its presence correlated with expression of CD38, relative to that of normal B-cell progenitors. In addition, the candidate LSC was not detectable in all MRD positive samples. The absence of the population in 40% of diagnostic and 40% of MRD positive samples does not support the use of this phenotype as a generic biomarker to track LSCs and suggests that this phenotype may be an artifact of CD38 underexpression rather than a biologically distinct LSC population. ClinicalTrials.gov Identifier: NCT00222612.

Mast cells from different molecular and prognostic subtypes of systemic mastocytosis display distinct immunophenotypes

BACKGROUND

Systemic mastocytosis (SM) is a heterogeneous group of disorders with distinct clinical and biological behavior. Despite this, little is known about the immunophenotypic features of the distinct diagnostic categories of SM.

OBJECTIVE

To analyze the immunophenotypic characteristics of bone marrow (BM) mast cells (MCs) of different subtypes of SM.

METHODS

Bone marrow samples from 123 patients with different subtypes of SM and 92 controls were analyzed for a broad panel of immunophenotypic markers by flow cytometry.

RESULTS

Three clearly different maturation-associated immunophenotypic profiles were found for BMMCs in SM. These different profiles were associated with both genetic markers of the disease and its clinical behavior. BMMCs from poor-prognosis categories of SM (aggressive SM and MC leukemia) typically showed an immature phenotype with clonal involvement of all myeloid lineages by the D816V stem cell growth factor receptor gene (KIT) mutation. In turn, a mature activated versus resting BMMC immunophenotype was commonly found among patients with good-prognosis subtypes of SM depending on whether they carried (indolent SM and clonal MC activation disorders) or not (well differentiated SM) the D816V KIT mutation.

CONCLUSION

Bone marrow MCs from SM show 3 different maturation-related immunophenotypic profiles that are associated with both the genetic markers of the disease and its clinical behavior.

Concurrent intensive chemotherapy and imatinib before and after stem cell transplantation in newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia. Final results of the CSTIBES02 trial

BACKGROUND

Imatinib, given concurrently or alternating with chemotherapy, has improved the response and survival of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) but relapses are still frequent. The aim of this study was to evaluate the feasibility and results of giving imatinib concurrently with intensive chemotherapy, stem cell transplantation and post-transplant imatinib maintenance therapy in patients with newly diagnosed Ph(+) ALL.

DESIGN AND METHODS

This was a phase II study of patients with newly diagnosed Ph(+) ALL given standard chemotherapy, together with imatinib (400 mg/day) until stem cell transplantation, followed by imatinib maintenance therapy for all patients regardless of the molecular status of the disease.

RESULTS

Of the 30 patients included, 27 (90%) achieved complete remission, one was resistant to treatment and two died during induction therapy. The percentages of major and complete molecular responses were 86% and 21% after induction, and 81% and 65% after consolidation, respectively. Similar results were observed assessing minimal residual disease by flow cytometry. Of the 27 patients who achieved complete remission, 21 underwent stem cell transplantation (16 allogeneic, 5 autologous). Imatinib (400 mg/day) could be administered after transplantation for a median of 3.9 months in 12 patients, although it was interrupted in 10 patients (in 2 cases because of side effects of the drug). Nine patients relapsed, four before and five after stem cell transplantation and eight patients died of transplant-related causes. With a median follow-up of 4.1 years, the probabilities (95% CI) of disease-free and overall survival were 30% (15% to 45%) and 30% (16% to 45%), respectively.

CONCLUSIONS

These results confirm that imatinib is an effective first-line treatment for adult Ph(+) ALL when given concurrently with chemotherapy, making stem cell transplantation feasible in a high proportion of patients. However, post-transplantation imatinib administration was limited, mainly because of transplantation-derived complications rather than drug-specific toxicity.

Quantitative flow cytometric analysis of membrane antigen expression

Immunological analysis for cell antigens has been performed by flow cytometry in a qualitative fashion for over thirty years. During that time it has become increasingly apparent that quantitative measurements such as number of antigens per cell provide unique and useful information. This unit on quantitative flow cytometry (QFCM) describes the most commonly used protocols, both direct and indirect, and the major methods of analysis for the number of antibody binding sites on a cell or particle. Practical applications include detection of antigen under- or overexpression in hematological malignancies, distinguishing between B cell lymphoproliferative disorders, and precise diagnosis of certain rare diseases.

Prognostic Value of Immunophenotyping in Multiple Myeloma: A Study by the PETHEMA/GEM Cooperative Study Groups on Patients Uniformly Treated With High-Dose Therapy

Purpose

To analyze the prognostic impact of immunophenotyping in patients with multiple myeloma (MM).

Patients and Methods

We have prospectively analyzed the prognostic impact of antigenic markers, assessed by multiparametric flow cytometry, in a series of 685 newly diagnosed MM patients that were uniformly treated according to the GEM 2000 protocol.

Results

Our results show that expression of both CD19 and CD28 as well as the absence of CD117 were associated with a significantly shorter progression free-survival (PFS) and overall survival (OS). Interestingly, the CD28 expression correlated with t(14;16) and del(17p), while CD117-negative patients were associated with t(4;14) and del(13q). Simultaneous assessment of CD28 and CD117 antigens allowed stratification of patients with MM into three risk categories: poor risk (CD28 positive CD117 negative), intermediate (either both markers negative or both positive), and good risk (CD28 negative CD117 positive), with PFS rates of 30, 37, and 45 months, respectively (P = .01), and OS rates of 45, 68, and not reached, respectively (P = .0001).

Conclusion

To the best of our knowledge, this is the first prospective analysis in which the prognostic impact of a relatively high number of antigenic markers has been simultaneously analyzed in a large series of uniformly treated patients, showing that the expression of several antigens (particularly CD28 and CD117) on bone marrow plasma cells from patients with MM can help to identify patients at high risk of progression.

Acute Lymphoblastic Leukemia: Diagnosis and Detection of Minimal Residual Disease Following Therapy

Flow cytometric immunophenotyping (FCI) is an important diagnostic modality in the evaluation of patients who have suspected or known acute lymphoblastic leukemia (ALL). It enables rapid identification, quantification, and immunophenotypic characterization of leukemic blasts, permitting accurate and timely diagnosis. Beyond facilitating the classification of ALL into fundamental diagnostic categories, FCI may anticipate recurrent cytogenetic and molecular abnormalities. FCI permits the detection of leukemic blasts after therapy at a level lower than that achievable by conventional microscopic examination. Flow cytometric detection of minimal residual disease is among the strongest prognostic factors in patients who have ALL and may provide an opportunity for more precise risk-adapted therapies.

Diagnostic pathways in acute leukemias: a proposal for a multimodal approach

Acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) each represent a heterogeneous complex of disorders, which result from diverse mechanisms of leukemogenesis. Modern therapeutic concepts are based on individual risk stratification at diagnosis and during follow-up. For some leukemia subtypes such as AML M3/M3v with t(15;17)/PML-RARA or Philadelphia-positive ALL targeted therapy options are available. Thus, optimal therapeutic conditions are based on exact classification of the acute leukemia subtype at diagnosis and are guided by exact and sensitive quantification of minimal residual disease during complete hematologic remission. Today, a multimodal diagnostic approach combining cytomorphology, multiparameter flow cytometry, chromosome banding analysis, accompanied by diverse fluorescence in situ hybridization techniques, and molecular analyses is needed to meet these requirements. As the diagnostic process becomes more demanding with respect to experience of personnel, time, and costs due to the expansion of methods, algorithms, which guide the diagnostic procedure from basic to more specific methods and which lead finally to a synopsis of the respective results, are essential for modern diagnostics and therapeutic concepts.

Sustained leukaemic phenotype after inactivation of BCR-ABLp190 in mice

Pharmacological inactivation of cancer genes or products is being used as a strategy for therapy in oncology. To investigate the potential role of BCR-ABLp190 cessation in leukaemia development, we generated mice carrying a tetracycline-repressible BCR-ABLp190 transgene. These mice were morphologically normal at birth, and developed leukaemias. Disease was characterized by the presence of B-cell blasts co-expressing myeloid markers, reminiscent of the human counterpart. BCR-ABLp190 activation can initiate leukaemia in both young and adult mice. Transitory expression of BCR-ABLp190 is enough to develop leukaemia. Suppression of the BCR-ABLp190 transgene in leukaemic CombitTA-p190 mice did not rescue the malignant phenotype, indicating that BCR-ABLp190 is not required to maintain the disease in mice. Similar results were obtained by inactivation of BCR-ABLp190 with STI571 (Gleevec; Novartis, East Hanover, NJ, USA) in leukaemic CombitTA-p190 mice. However, gradual suppression of BCR-ABLp190 in leukaemic CombitTA-p190 mice identified a minimum level of BCR-ABLp190 expression necessary to revert the specific block in B-cell differentiation in the leukaemic cells. Overall, the findings indicate that BCR-ABLp190 appears to cause epigenetic and/or genetic changes in tumour-maintaining cells that render them insensitive to BCR-ABLp190 inactivation.

Flow Cytometric Analysis of Normal and Neoplastic Mast Cells: Role in Diagnosis and Follow-Up of Mast Cell Disease

Human mast cells (MCs) are directly derived from human pluripotent CD34+ stem and progenitor hematopoietic cells with stem cell factor being a critical growth factor supporting human MC proliferation, differentiation, and survival. Because of the advantages that flow cytometry offers (it allows rapid, objective, and sensitive multiparameter analysis of high numbers of cells from a sample, with information being provided on the basis of a single cell), it has become the method of choice in the past decade for immunophenotypic identification, enumeration, and characterization of human MCs in bone marrow and other tissue specimens.

The chemosensitivity to therapy of childhood early B acute lymphoblastic leukemia could be determined by the combined expression of CD34, SPI-B and BCR genes

We have identified genes differentially expressed in childhood early B acute lymphoblastic leukemia at diagnosis, according to chemosensitivity. Chemosensitive (M1) and chemoresistant (M3) patients present <5% and >25% of residual leukemic blasts at 21 days of treatment, respectively. The expression profiles of 4205 genes for 32 patients included in the FRALLE93 protocol have been determined using microarray. From differential analysis, CD34, SPI-B and BCR distinguished M1 from M3 patients using microarray and RT-PCR data. Linear discriminant analysis (LDA) and cross-validation show that the combined expression of these three genes classify and predict correctly around 90% and 80% of patients, respectively.

Genetic heterogeneity of BCR/ABL+ adult B-cell precursor acute lymphoblastic leukemia: impact on the clinical, biological and immunophenotypical disease characteristics

Philadelphia-positive (Ph(+)) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a genetically heterogeneous disease with a very poor prognosis. In this study, we analyzed the frequency of supernumerary Ph, trisomy 8, monosomy 7, and del(9p21) by FISH and its relationship with the characteristics of the disease, in 46 BCR/ABL(+) adult BCP-ALL patients. The frequency of supernumerary Ph, trisomy 8, monosomy 7 and del(9p21) was 30%, 20%, 15%, and 24%, respectively. Although all patients displayed a BII/common phenotype, supernumerary Ph and trisomy 8 were associated with higher expression of CD19 and CD22 and of CD19, CD34, CD45, and HLA-DR, respectively; in turn, cases with monosomy 7 showed lower CD19, CD22, CD34, and cCD79a and del(9p21)(+) blasts were CD13(-) and CD33(-). Overall, similar clinical and hematological features were observed at presentation, independently of the underlying genetic abnormalities. However, relapse-free survival (RFS) was significantly shorter in cases with supernumerary Ph, trisomy 8, and del(9p21), the latter being the most powerful independent prognostic factor for RFS.

SLUG in cancer development

The SNAIL-related zinc-finger transcription factor, SLUG (SNAI2), is critical for the normal development of neural crest-derived cells and loss-of-function SLUG mutations have been proven to contribute to piebaldism and Waardenburg syndrome type 2 in a dose-dependent fashion. While aberrant induction of SLUG has been documented in cancer cells, relatively little is known about the consequences of SLUG overexpression in malignancy. To investigate the potential role of SLUG overexpression in development and in cancer, we generated mice carrying a tetracycline-repressible Slug transgene. These mice were morphologically normal at birth, and developed mesenchymal tumours (leukaemia and sarcomas) in almost all cases examined. Suppression of the Slug transgene did not rescue the malignant phenotype. Furthermore, the BCR-ABL oncogene, which induces Slug expression in leukaemic cells, did not induce leukaemia in Slug-deficient mice, implicating Slug in BCR-ABL leukaemogenesis in vivo. Overall, the findings indicate that while Slug overexpression is not sufficient to cause overt morphogenetic defects in mice, they demonstrate a specific and critical role for Slug in the pathogenesis of mesenchymal tumours.

Genetic Abnormalities and Patterns of Antigenic Expression in Multiple Myeloma

Myelomatous plasma cells show a high heterogeneity both in their immunophenotypic characteristics as well as in their cytogenetic features. Thus far, no extensive studies have been carried out to explore whether such antigenic diversity is associated with specific genetic characteristics. We have investigated the relationship between the immunophenotypic profile at plasma cell and both their DNA ploidy status (evaluated by flow cytometry) and specific genetic features (ascertained by fluorescence in situ hybridization) in a large series of 915 patients with newly diagnosed multiple myeloma. The non-hyperdiploid multiple myeloma group (n = 454, 52%) was associated with a significantly higher frequency of positivity for CD28 and CD20 as well as a higher incidence of CD56(-) and CD117(-) cases (P < 0.001). Remarkably, 13q deletion and immunoglobulin heavy chain (IGH) gene rearrangements, which were significantly more common in non-hyperdiploid multiple myeloma, showed a strong association with CD117(-) cases. IGH translocation to 11q13 was associated with reactivity for CD20 (P < 0.001), down-regulation of CD56 (P < 0.001), and lack of expression of CD117 (P = 0.001). By contrast, IGH translocations to other chromosome partners were almost exclusively found among CD20(-) and CD117(-) cases (P < 0.001). These results suggest that genetic categories in multiple myeloma exhibit particular immunophenotypic profiles which in turn are strongly associated with the DNA ploidy status.

Additional clonal abnormalities in Philadelphia-positive ALL and CML demonstrate a different cytogenetic pattern at diagnosis and follow different pathways at progression

The cytogenetic patterns in addition to the Philadelphia translocation in Philadelphia-positive (Ph+) ALL and chronic myeloid leukemia (CML) is heterogenous. We investigated 154 patients with Ph+ ALL at diagnosis or at relapse and 174 patients with different phases of CML. Ph+ ALL at diagnosis demonstrated a heterogenous pattern with a high frequency of numerical and structural chromosomal aberrations. CML at diagnosis presented with rare additional chromosomal changes. In Ph+ ALL, the pathway from diagnosis to relapse was characterized by the acquisition of a higher number of chromosomal aberrations, but the pattern of frequent aberrations at relapse did not differ from that observed at diagnosis. In contrast, in CML the pathway from chronic to the advanced phases was characterized by the acquisition of new chromosomal changes and by the development of karyotype complexity. In addition, the investigation of 10 cases of lymphoid blast crisis of CML showed significant differences in the karyotype in comparison to Ph+ ALL at diagnosis. Therefore, the karyotype can be helpful in discriminate de novo lymphoid blast crisis of CML from de novo Ph+ ALL. In conclusion, we were able to demonstrate that the cytogenetic patterns of Ph+ ALL and of CML are different at diagnosis and furthermore follow different pathways during progression or relapse.

Adult acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) in adults is a relatively rare neoplasm with a curability rate around 30% at 5 years. This consideration makes it imperative to dissect further the biological mechanisms of disease, in order to selectively implement an hitherto unsatisfactory success rate. The recognition of discrete ALL subtypes (some of which deserve specific therapeutic approaches, like T-lineage ALL (T-ALL) and mature B-lineage ALL (B-ALL)) is possible through an accurate combination of cytomorphology, immunophenotytpe and cytogenetic assays and has been a major result of clinical research studies conducted over the past 20 years. Two-three major prognostic groups are now easily identifiable, with a survival probability ranging from <10 to 20% (Philadelphia-positive ALL) to about 50-60% (low-risk T-ALL and selected patients with B-lineage ALL). These issues are extensively reviewed and form the basis of current knowledge. The second major point relates to the emerging importance of studies that reveal a dysregulated gene activity and its clinical counterpart. It is now clear that prognostication is a complex matter ranging from patient-related issues to cytogenetics to molecular biology, including the evaluation of minimal residual disease (MRD) and possibly gene array tests. On these bases, the role of a correct, highly personalised therapeutic choice will soon become fundamental. Therapeutic progress may be obtainable through a careful integration of chemotherapy, stem cell transplantation, and the new targeted treatments with highly specific metabolic inhibitors and humanised monoclonal antibodies.

Correlation between karyotype and quantitative immunophenotype in acute myelogenous leukemia with t(8;21)

Acute myelogenous leukemia with t(8;21) is a distinct clinicopathologic entity in which the malignant myeloblasts display a characteristic pattern of surface antigen expression. Quantitative analysis of surface marker expression in patients with this chromosomal abnormality compared to acute myelogenous leukemia patients with a different karyotype has not been reported. From 305 consecutive newly diagnosed acute myelogenous leukemia patients underwent immunophenotyping and cytogenetic analysis at our center; 16 patients (5.2%) had a t(8;21). Fluorescence intensity values were obtained, using a set of reference microbeads, by conversion of mean channel fluorescence to molecular equivalent of soluble fluorochrome. Patients with t(8;21) displayed higher levels of CD34, HLA-DR and MPO expression (P < 0.001 for each) and lower levels of CD13 (P = 0.03) and CD33 (P = 0.02) expression. In order to study the sensitivity, specificity and predictive value of these markers, molecular equivalent of soluble fluorochrome thresholds were statistically determined. The statistically established threshold for each of the individual markers (CD34 > 60.5 x 10(3), HLA-DR > 176.1 x 10(3), MPO > 735.1 x 10(3), CD13 < 24.3 x 10(3) and CD33 < 17.3 x 10(3)) had a sensitivity of 100%, a specificity of 62-92% and a positive predictive value of 7-45%. In multivariate analysis, two quantitative patterns (CD34 > 60.5 x 10(3) and MPO > 176.1 x 10(3); CD33 < 17.3 x 10(3) and MPO > 176.1 x 10(3)) had a sensitivity, specificity and positive predictive value of 100%. These aberrant phenotypic patterns might help identify patients with t(8;21) at diagnosis and could be useful in minimal residual disease monitoring.

Trisomy 4 as the sole cytogenetic abnormality in a patient with T-cell acute lymphoblastic leukemia

Trisomies as sole cytogenetic abnormalities are extremely rare in acute lymphoblastic leukemia (ALL). We describe here the clinical features and immunophenotyping, cytogenetic, and fluorescence in situ hybridization (FISH) findings in a T-cell ALL patient with trisomy 4 as the sole cytogenetic abnormality. The leukemic clone was positive for CD2, CD7, CD34, and terminal deoxynucleotidyl transferase (TdT); CD13 was weakly expressed. Data on the tracking of the leukemic clone with immunophenotyping, cytogenetic, and FISH studies are discussed. The present case is compared with the three previous reported cases of trisomy 4 in ALL. Due to the rarity of this cytogenetic abnormality, its prognostic significance in ALL remains unclear.

Flow cytometric detection of minimal residual disease in acute lymphoblastic leukemia

Assessment of minimal residual disease (MRD) during the first months of therapy gives information on the timely response to treatment, and proves to be a powerful and independent indicator of treatment outcome in patients with acute lymphoblastic leukemia (ALL). Immunological evaluation by flow cytometry (FCM) is one of the most attractive approaches to this. The present review summarizes the historical development of this approach over the last 20 years, and shows that current methodology is based on the existence of leukemia-associated patterns of derangement in antigen expression with respect to normal differentiation or location of occurrence. Recent clinical studies are summarized which proved that FCM is applicable to more than 90% of patients with ALL and gives prognostic information comparable to polymerase chain-reaction (PCR)-based technology. Ongoing efforts based on parallel application of both technologies are explained which are designed to clarify which approach bears the best cost-relevance ratio in order to be broadly used in the future for risk assessment and tailoring of treatment modalities. Concluding perspectives relate to further technical developments like usage of peripheral blood (PB) instead of bone marrow (BM), absolute quantification, or strategic placement of investigative time-points, which may allow to simplify the MRD approach and thus augment it's economic efficiency.