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

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.

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.

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.

Prognostic value of the immune target CEACAM6 in cancer: a meta-analysis

BACKGROUND

Identification of membrane proteins differentially expressed on tumor cells is a key step in drug development. The carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a cell adhesion protein belonging to the immunoglobulin superfamily. Here, we explore the prognostic role CEACAM6 expression on patient outcome in cancer.

METHODS

A systematic search for studies evaluating the association between tumor expression of CEACAM6 and overall survival (OS) and disease-free survival (DFS) was performed. Hazard ratios (HR) were pooled in a meta-analysis using generic inverse variance and random effect modeling. Subgroup analyses were conducted based on tumor type and method of HR extraction.

RESULTS

Sixteen studies met the inclusion criteria. CEACAM6 expression was associated with worse OS [HR = 1.96, 95% confidence interval (CI) = 1.51-2.53], and DFS (HR = 2.49, 95% CI = 2.01-3.07) with subgroup analysis showing no significant differences between disease site subgroups.

CONCLUSIONS

High expression of CEACAM6 is associated with worse OS and DFS in different malignancies. CEACAM6 is a target for the future development of novel therapeutics.

Adult Ph-positive acute lymphoblastic leukemia-current concepts in cytogenetic abnormalities and outcomes

Recurrent chromosomal and molecular abnormalities characterize acute lymphoblastic leukemia (ALL) subtypes in both adult and pediatric patients and are of great value for diagnosis, risk stratification, disease monitoring and treatment selection. The Philadelphia (Ph) chromosome, which creates a novel hybrid gene called BCR-ABL1, is the most common cytomolecular genetic abnormality in adult ALL patients. As the understanding of the genetic characteristics of Ph-positive ALL continues to improve, the prognostic value of cytogenetic abnormalities is becoming increasingly recognized. It is likely that the clinical guidelines and recommendations will also evolve. Accordingly, it will be very important to effectively and economically utilize current knowledge to guide treatment decisions within the clinical context of each patient. In this review, we will summarize the advances in the understanding of cytogenetic abnormalities in adult patients with Ph+ ALL, with an emphasis on the incidence, characteristics and prognosis of different types of abnormalities, to provide a basis for the clinical prognostic stratification and precise individualized treatment of these patients.

Chronic myeloid leukemia presenting in lymphoblastic crisis, a differential diagnosis with Philadelphia-positive B-lymphoblastic leukemia

Rare patients with chronic myeloid leukemia (CML) can present initially in lymphoblastic crisis (LBC) mimicking Ph + B-lymphoblastic leukemia (B-ALL). We retrospectively reviewed 275 adults who diagnosed initially as Ph + B-ALL and identified 28 patients with at least one of three features supporting the diagnosis of CML-LBC: 1) a large discrepancy between the blast count and Ph + clone; 2) Ph + clone persistent when B-ALL in remission; 3) BCR/ABL1 fusion detected in segmented cells. BCR-ABL1 fusions were p210 in 25 patients and p190 in 3 patients. In comparison to patients with Ph + B-ALL, patients with CML-LBC were older; had higher leukocyte and absolute neutrophil counts; higher immature myeloid cells in peripheral blood; lower blast counts; and inferior outcomes. In addition, we prospectively analyzed 26 patients with Ph + B-lymphoblastic leukemia and identified 8 patients with features more consistent with CML-LBC. These findings highlight the importance of distinguishing CML-LBC from de novo Ph + B-ALL.

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.

Prognostic significance of a normal karyotype in adult patients with BCR-ABL1-positive acute lymphoblastic leukemia in the tyrosine kinase inhibitor era

OBJECTIVE

The occurrence of cryptic Philadelphia (Ph) chromosome translocation is rare in BCR-ABL1-positive acute lymphoblastic leukemia (BCR-ABL1+ ALL) and is of unknown significance in the tyrosine kinase inhibitor (TKI) era.

METHODS

We retrospectively studied a series of adult patients receiving TKI-based therapy to evaluate the prognostic impact of the normal karyotype (NK) (n=22) in BCR-ABL1+ ALL by comparison with the isolated Ph+ karyotype (n=54).

RESULTS

There were no statistically significant differences in clinical characteristics and complete remission rate between the two groups. Compared with the isolated Ph+ group, the NK/BCR-ABL1+ group had a higher relapse rate (55.0% versus 29.4%, p=0.044). Overall survival (OS) and disease-free survival (DFS) were significantly shorter in the NK/BCR-ABL1+ group than in the isolated Ph+ group [median OS: 24.5 versus 48.6 (months), p=0.013; median DFS: 11.0 (months) versus undefined, p=0.008]. The five-year OS and DFS for patients with NK/BCR-ABL1+ were 19.2% and 14.5%, respectively; those for patients with isolated Ph+ were 49.5% and 55.7%, respectively. Thirty-four (44.7%) patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in this study. Among the patients who received allo-HSCT, the median OS and DFS in the NK/BCR-ABL+ group (n=9) were 35.5 and 27.5 months, respectively, while those in the isolated Ph+ group (n=25) were undefined. There was a trend of significant statistical difference in the OS between the two subgroups (p=0.066), but no significant difference in the DFS. Multivariate analysis revealed that NK was independently associated with worse OS and DFS in BCR-ABL1+ ALL patients [Hazard ratio (HR) 2.256 (95% confidence interval (CI), 1.005-5.066), p=0.049; HR 2.711 (95% CI, 1.319-5.573), p=0.007].

CONCLUSION

Our results suggest that the sub-classification of an NK could be applied in the prognostic assessments of BCR-ABL1+ ALL. In addition, allo-HSCT should be actively performed to improve prognosis in these patients.

Chronic Myeloid Leukemia: Beyond BCR-ABL1

PURPOSE OF REVIEW

In this review, we emphasize up-to-date practical cytogenetic and molecular aspects of chronic myeloid leukemia (CML) and summarize current knowledge on tyrosine kinase inhibitor (TKI) resistance and treatment response monitoring of CML.

RECENT FINDINGS

The introduction of TKIs has changed the natural course of CML and markedly improved patient survival. Over the past decades, many research efforts were devoted to elucidating the leukemogenic mechanisms of BCR-ABL1 and developing novel TKIs. More recent studies have attempted to answer new questions that have emerged in the TKI era, such as the cytogenetic and molecular bases of treatment failure and disease progression, the clinical impact of genetic aberrations in Philadelphia chromosome (Ph)-positive and Ph-negative cells, and the biological significance of Ph secondarily acquired during therapy of other hematological neoplasms. Recent progresses in the understanding of the cytogenetic and molecular mechanisms underlying therapeutic failure and disease progression have improved the risk stratification of CML and will be helpful in the design of novel therapeutic strategies.

Lymphoblastic leukemia following myelodysplastic syndromes or myelodysplastic/myeloproliferative neoplasms

Lymphoblastic leukemia (ALL) following myelodysplastic syndrome (MDS) or myelodysplastic/myeloproliferative neoplasm (MDS/MPN) is very rare. We report five cases: four had ALL diagnosed after MDS or MDS/MPN and one had ALL and MDS diagnosed simultaneously. At the onset of ALL, all patients showed co-existing MDS or MDS/MPN. Map-back FISH was performed in four patients, showing that ALL and MDS were cytogenetically related in two patients and unrelated in the other two patients. All five patients were treated with ALL-based chemotherapies, two patients with ALL clonally related to MDS were refractory to the therapies, whereas the other three patients achieved remission. We conclude that ALL developed after MDS is extremely rare. In some patients, ALL is clonally related to MDS and these patients may be refractory to ALL-based chemotherapies. In other patients who have no evidence of clonal relation between ALL and MDS, these patients more likely respond to ALL-based treatment regimens.

Dasatinib as an investigational drug for the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults

INTRODUCTION

Acute lymphoblastic leukemia (ALL) with BCR-ABL1 translocation is an aggressive malignancy that is usually treated with intensive chemotherapy with the possibility of allogeneic stem cell transplantation. The encoded fusion protein may be important for leukemogenesis; clinical studies show that dasatinib has an antileukemic effect in combination with steroids alone or intensive chemotherapy. Areas covered: Relevant publications were identified through literature searches (the used terms being acute lymphoblastic leukemia plus dasatinib) in the PubMed database. We searched for original articles and reviews describing the pharmacology and clinical use of dasatinib in ALL with BCR-ABL1. The mechanism of action, pharmacology and clinical study findings are examined. Expert opinion: Dasatinib is associated with a high complete remission rate in ALL when used alone and in combination with steroids or intensive chemotherapy. However, mutations at T315 and F317 are associated with dasatinib resistance. Overall toxicity has been acceptable in these studies and no unexpected toxicity was observed. It is not known whether the antileukemic effect of dasatinib differs between subsets of BCR-ABL1⁺ patients or is attributed to inhibition of the fusion protein alone, or a combined effect on several kinases, and whether dasatinib-containing combination treatment should be preferred in these patients instead of other emerging strategies, e.g. monoclonal antibodies.

Identification of chromosomal abnormalities and genomic features in near-triploidy/tetraploidy-acute leukemia by fluorescence in situ hybridization

Background

Near-triploidy/tetraploidy is rarely found in acute leukemia. Only limited data are available to characterize this condition, and it remains largely unknown.

Patients and methods

In our study, we performed karyotype analysis on 1,031 patients diagnosed with acute leukemia from 2006 to 2018. A total of 10 patients of near-triploidy/tetraploidy karyotype were enrolled. Two cases of near-triploidy (66-79 chromosomes) and eight cases of near-tetraploidy (84-100 chromosomes) were identified. Bone marrow samples of these 10 patients were analyzed by fluorescence in situ hybridization with 19 commercially available probes that detected a small portion of gene alterations and large regions of chromosome amplifications.

Results

Of the six patients with acute myelocytic leukemia, we detected three cases of double t(8;21)(q22;q22) that have not been previously reported, and one of them demonstrated ins(21;8) (q22;q24q22). We also describe a novel pediatric case carrying double t(15;17)(q22;q21) and receiving targeted treatment with all-trans retinoic acid therapy. To date, this case has responded well to the regimen and has shown continuous complete remission. All patients received chemotherapy. One of them received allogeneic hematopoietic stem cell transplant (HSCT) and survived for 22 months. Eight of the 10 patients died, and the median overall survival was 11 months.

Conclusion

Using fluorescence in situ hybridization, we identified the distinct complex karyotype of near-triploidy/tetraploidy and provided further prognostic information. Tetraploidy acute promyelocytic leukemia had favorable prognosis; thus, HSCT was not necessary. The case of insertion t(21;8)(q22;q24q22) in tetraploidy responded poorly to chemotherapy and achieved molecular remission with difficultly. Data from patients in this group indicated that near-triploidy/tetraploidy acute leukemia has poor prognosis and new therapy is urgently needed.

Flow cytometric predictive scoring systems for common fusions ETV6/RUNX1, BCR/ABL1, TCF3/PBX1 and rearrangements of the KMT2A gene, proposed for the initial cytogenetic approach in cases of B-acute lymphoblastic leukemia

INTRODUCTION

In B-acute lymphoblastic leukemia (B-ALL), the identification of cytogenetic prognostic factors is important for stratifying patients into risk groups and tailoring treatment accordingly. The purpose of this study was to propose flow cytometric (FCM) scoring systems (SSs) for predicting t(12;21)(p13;q22), t(9;22)(q34;q11), t(11q23), and t(1;19)(q23;p13.3) translocations.

METHODS

We analyzed retrospectively the FCM immunophenotype of 377 patients with B-ALL with regard to the major cytogenetic findings revealed by interphase fluorescence in situ hybridization (i-FISH). Comparing descriptive data on the expression of each antigen and performing receiver operating characteristic (ROC) analysis, we identified the most reliable predictive markers for each translocation and sought to establish a specific SS for each translocation, based on specific antibody panels.

RESULTS

CD27, CD9, CD66c, CD10, CD25, and CD34 were employed for the prediction of t(12;21), CD25, CD38, CD34, and CD66c for t(9;22), NG2, CD10, CD15, CD34, and CD20 for t(11q23), and CD34, cμ, CD123, and CD66c for t(1;19). The sensitivity and specificity, respectively, of each predictive score were 89.29% and 96.15% for t(12;21), 75.00% and 88.19% for t(9;22), 84.21% and 99.04% for t(11q23), and 85.71% and 92.71% for t(1;19).

CONCLUSION

Four highly specific and significantly sensitive FCM-obtained SSs are proposed for the prediction of the four major translocations observed in patients with B-ALL. Prospective evaluation of the proposed SSs could lead to a better targeted cytogenetic investigation and therefore to more cost-effective laboratory practice.

An Unsuspected Finding of t(9;22): A Rare Case of Philadelphia Chromosome-Positive B-Lymphoblastic Lymphoma

While rare, cases of isolated extramedullary disease of B-cell Lymphoblastic Lymphoma (B-LBL) without morphologic bone marrow involvement have been described. In this report, we illustrate the case of an elderly gentleman who presented with isolated testicular and vertebral LBL involvement but had no morphologic bone marrow involvement. The initial plan of treatment was to treat along the lines of Philadelphia negative B-ALL/LBL. During this time, fluorescence in situ hybridization (FISH) and PCR testing for BCR-ABL1 rearrangements were being performed on the marrow specimens as a part of routine diagnostic workup. While the FISH returned negative, PCR testing unexpectedly detected BCR-ABL1 fusion transcripts at a low level of 0.48%. Given their presence, we performed FISH for BCR/ABL1 rearrangement in both testicular and L5 vertebral specimens which were 80–90% positive. He subsequently received rituximab, hyper-CVAD, and dasatinib, along with prophylactic intrathecal prophylactic chemotherapy. The patient achieved a prolonged remission but eventually relapsed, 4 years later. Had it not been for this fortuitous discovery, the patient would not have been treated with tyrosine kinase inhibitors. We emphasize that FISH and PCR testing for BCR-ABL1 rearrangement are integral to arriving at an accurate diagnosis and should be routinely tested on B-LBL biopsy specimens.

Tetraploidy/near-tetraploidy acute myeloid leukemia

A tetraploid/near tetraploid (T/NT) karyotype is a rare finding in acute myeloid leukemia (AML). Here we report 38 AML patients with a T/NT karyotype, including 26 men and 12 women with a median age of 65 years. T/NT karyotype was detected at initial diagnosis of AML in 16 patients, and acquired during the course of disease in 22 patients. All patients showed large blasts with frequent prominent nucleoli, cytoplasmic vacuoles and/or inclusions, nuclear irregularity and/or budding. Eleven patients had a non-complex and 27 had a complex T/NT karyotype; 21 patients also had pseudodiploid and/or triploid clones. After T/NT karyotype detection, 32 patients received chemotherapy and 10 also received stem cell transplant. After a median of 6.2 months follow-up, 32 patients died of disease or complications, 5 were alive with complete remission, and 1 alive with persistent AML. Median overall survival (OS) was 5 months. Patients with a non-complex T/NT karyotype had a significantly superior OS compared to those with a complex T/NT karyotype (10.7 vs. 3.4 months, p=0.0280). We conclude that T/NT karyotype in AML is often associated with distinctive morphologic features and conveys generally poor outcomes. Distinction of complex versus non-complex T/NT karyotype provides further prognostic information.

CD25 Expression in B Lymphoblastic Leukemia/Lymphoma Predicts t(9;22)(q34;q11)/Philadelphia Chromosome Translocation (Ph) and Is Associated With Residual Disease in Ph-Negative Patients

OBJECTIVES

CD25 expression is associated with t(9;22)(q34;q11)/Philadelphia chromosome translocation (Ph); BCR-ABL1 rearrangement in B lymphoblastic leukemia/lymphoma (B-LL). However, the significance of CD25 expression in Ph negative (Ph-) B-LL regarding residual disease (RD) and genetic abnormalities is largely unknown.

METHODS

CD25 expression by flow cytometry (FC) was correlated with Ph status in 95 newly diagnosed B-LL patients and with RD status in day 29 marrow measured by FC in the context of cytogenetic risk stratification in Ph- patients.

RESULTS

CD25 expression was greater in Ph positive (Ph+) patients (80%) than in Ph- patients (17%), predicting Ph+ with 80% sensitivity and 86% specificity. In Ph- patients, CD25 expression (in 14 patients, 16%) was associated with RD in the cytogenetic intermediate-risk group: detectable RD in 50% of CD25+ patients vs 14% of CD25- patients. Interestingly, one CD25+/Ph- patient had a Ph-like genotype ( ZC3HAV1-ABL2 rearrangement), and another had dual MYC-IGH and BCL2-IGH rearrangements.

CONCLUSIONS

Our findings not only confirm the predictive power of CD25 expression for Ph+ but also demonstrate that CD25 expression is associated with RD (a biomarker correlated with prognosis) in Ph- patients. The latter finding is likely associated with underlying molecular abnormalities, including Ph-like genotype.

Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Is Separated into Two Subgroups Associated with Survival by BCR-ABL Fluorescence in situ Hybridization of Segmented Cell Nuclei: Report from a Single Institution

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) may include the lymphoid blast crisis of chronic myeloid leukemia (CML-BC). We applied fluorescence in situ hybridization (FISH) of the BCR-ABL fusion gene to peripheral blood and/or bone marrow smears to determine whether the fusion was restricted to mononuclear cell nuclei or if segmented cell nuclei representing mature neutrophils also carried the fusion (Seg-FISH). Among 20 patients with Ph+ ALL without a prior diagnosis of CML, 9 were Seg-FISH+ and 11 were Seg-FISH-. Seg-FISH+ cases were characterized by a higher rate of p210-type BCR-ABL transcripts, higher white cell and blast counts, and a higher rate of myeloid and T-lymphoid antigen expression than Seg-FISH- cases, in addition to 'major route' cytogenetic abnormalities associated with CML-BC. Eighteen patients were treated with tyrosine kinase inhibitors (TKIs) either alone or in combination with multiagent chemotherapy, and 7 underwent allogeneic hematopoietic stem cell transplantation. Progression-free and overall survivals were greater in the Seg-FISH+ group than in the Seg-FISH- group. These results suggest that the Seg-FISH+ group represents lymphoid CML-BC that occurs de novo, while the Seg-FISH- represents Ph+ ALL in the strict sense, and the two groups are associated with survival when treated with TKIs or TKI-combined therapy.

Acute leukaemia and myelodysplastic syndromes with chromosomal rearrangement involving 11q23 locus, but not MLL gene

AIMS

Chromosome 11q23 translocations, resulting in MLL (KMT2A) rearrangement, have been well characterised in acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). However, little is known of haematopoietic neoplasms associated with 11q23 translocation but without MLL rearrangement (11q23+/MLL-). The aim of this study is to characterise such cases with 11q23+/MLL-.

METHODS AND RESULTS

We retrospectively searched our database for cases with haematopoietic malignancies with 11q23+/MLL-. We identified nine patients, two with AML, two with B-lymphoblastic leukaemia (B-ALL); two with T-lymphoblastic leukaemia (T-ALL), two with myelodysplastic syndrome (MDS) and one with chronic myelomonocytic leukaemia (CMML). The translocations included t(X;11)(p11.2;q23), t(2;11)(p21;q23), t(6;11)(q27;q23), t(8;9;11)(q13;q13;q23), t(11;11)(p15;q23), t(11;14)(q23;q24) and t(11;15)(q23;q14). Five of six patients with acute leukaemia had received chemotherapy and detection of 11q23 translocation occurred at time of disease relapse. Both patients with MDS and the patient with CMML had 11q23 translocation detected at time of initial diagnosis, all three patients progressed to AML after >1 year on hypomethylating agent therapy. All patients received risk-adapted therapies, including stem cell transplant in five patients. At the last follow-up, eight patients died with a median overall survival of 14 months.

CONCLUSIONS

11q23+/MLL- occurs rarely, involving different partner chromosomes and showing clinical and pathological features and disease subtypes different from those cases with MLL rearrangement. 11q23+/MLL- appears to be associated with clonal evolution/disease progression in acute leukaemia, a high risk for AML progression in MDS/CMML and a high incidence of disease relapse.

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.

ADAM28 overexpression regulated via the PI3K/Akt pathway is associated with relapse in de novo adult B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) in adults is a very challenging disease. Relapse following remission after induction chemotherapy remains the major barrier to patient survival. ADAM28 is overexpressed in several human tumors and is related to cell proliferation and lymph node metastasis. To date, no information has been available on the prognostic role of ADAM28 in B-ALL. Fifty consecutive patients with de novo B-ALL and 22 healthy donors were enrolled in this study and were followed for 2.8 years. Our data suggested that ADAM28 expression in B-ALL patients was significantly increased (P<0.0001). Patients experiencing disease relapse exhibited significantly increased ADAM28 expression, compared with those with favorable outcomes (P=0.0094). Notably, ADAM28 overexpression was associated with lower probabilities of relapse-free survival (RFS) and event-free survival (EFS) (P<0.001) and was a significant prognostic factor (P<0.001). In vitro, the PI3K/Akt pathway inhibitor, as well as arsenic trioxide (ATO), down-regulated ADAM28 expression. Our results were the first to indicate that ADAM28 overexpression in B-ALL patients is correlated with relapse. ADAM28 overexpression is potentially regulated by the PI3K/Akt pathway. These data demonstrate that ADAM28 might serve as a novel biomarker for evaluating relapse in B-ALL and as a potential therapeutic target in B-ALL patients.

The functional interplay between the t(9;22)-associated fusion proteins BCR/ABL and ABL/BCR in Philadelphia chromosome-positive acute lymphatic leukemia

The hallmark of Philadelphia chromosome positive (Ph⁺) leukemia is the BCR/ABL kinase, which is successfully targeted by selective ATP competitors. However, inhibition of BCR/ABL alone is unable to eradicate Ph⁺ leukemia. The t(9;22) is a reciprocal translocation which encodes not only for the der22 (Philadelphia chromosome) related BCR/ABL, but also for der9 related ABL/BCR fusion proteins, which can be detected in 65% of patients with chronic myeloid leukemia (CML) and 100% of patients with Ph⁺ acute lymphatic leukemia (ALL). ABL/BCRs are oncogenes able to influence the lineage commitment of hematopoietic progenitors. Aim of this study was to further disclose the role of p96^ABL/BCR for the pathogenesis of Ph⁺ ALL. The co-expression of p96^ABL/BCR enhanced the kinase activity and as a consequence, the transformation potential of p185^BCR/ABL. Targeting p96^ABL/BCR by RNAi inhibited growth of Ph⁺ ALL cell lines and Ph⁺ ALL patient-derived long-term cultures (PD-LTCs). Our in vitro and in vivo stem cell studies further revealed a functional hierarchy of p96^ABL/BCR and p185^BCR/ABL in hematopoietic stem cells. Co-expression of p96^ABL/BCR abolished the capacity of p185^BCR/ABL to induce a CML-like disease and led to the induction of ALL. Taken together our here presented data reveal an important role of p96^ABL/BCR for the pathogenesis of Ph⁺ ALL.

The t(9;22) is a reciprocal translocation, which causes chronic myeloid leukemia (CML) and a subset of high risk acute lymphatic leukemia (ALL). The derivative chromosome 22 is the so called Philadelphia chromosome (Ph) which encodes the BCR/ABL kinase. Targeting BCR/ABL by selective ATP competitors, such as imatinib or nilotinib, is a well validated therapeutic concept, but unable to definitively eradicate the disease. Little is known about the role of the fusion protein encoded by the reciprocal derivative chromosome 9, the ABL/BCR. In models of Ph⁺ ALL we show that the functional interplay between ABL/BCR and BCR/ABL not only increases the transformation potential of BCR/ABL but is also indispensable for the growth and survival of Ph⁺ ALL leukemic cells. The presence of ABL/BCR changed the phenotype of the leukemia most likely due to its capacity to influence the stem cell population as shown by our in vivo data. Taken together our here presented data reveal an important role of p96^ABL/BCR for the pathogenesis of Ph⁺ ALL.

MLL gene amplification in acute myeloid leukemia and myelodysplastic syndromes is associated with characteristic clinicopathological findings and TP53 gene mutation

MLL gene rearrangements are well-recognized aberrations in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). In contrast, MLL gene amplification in AML/MDS remains poorly characterized. Here, we report a series of 21 patients with myeloid neoplasms associated with MLL gene amplification from 1 institution. This series included 13 men and 8 women, with a median age of 64 years. Eleven patients presented as AML with myelodysplasia-related changes, 6 as therapy-related AML, and 4 as therapy-related MDS. All patients had a highly complex karyotype, including frequent -5/del(5q), -18, and -17/del(17p) abnormalities; 16 patients were hypodiploid. TP53 mutations were detected in all 12 patients tested, and 3 patients showed TP53 mutation before MLL amplification. Morphologically, the leukemic cells frequently showed cytoplasmic vacuoles, bilobed nuclei, and were associated with background dyspoiesis. Immunophenotypically, 15 patients had a myeloid and 4 had myelomonocytic immunophenotype. Laboratory coagulopathies were common; 7 patients developed disseminated intravascular coagulopathy, and 3 died of intracranial bleeding. All patients were refractory to therapy; the median overall survival was 1 month, after MLL gene amplification was detected. We concluded that AML/MDS with MLL gene amplification is likely a subset of therapy-related AML/MDS or AML with myelodysplasia-related changes, associated with distinct clinicopathological features, frequent disseminated intravascular coagulopathy, a highly complex karyotype, TP53 deletion/mutation, and an aggressive clinical course.

Expression of CD25 is a specific and relatively sensitive marker for the Philadelphia chromosome (BCR-ABL1) translocation in pediatric B acute lymphoblastic leukemia

BACKGROUND

Precursor B acute lymphoblastic leukemia (B-ALL) is the most common cancer in children and overall, has an excellent prognosis. However, the Philadelphia chromosome translocation (Ph+), t(9;22)(q34;q11), is present in a small subset of patients and confers poor outcomes. CD25 (IL-2 receptor alpha chain) expression has been associated with Ph+ B-ALL in adults, but no similar study has been performed in pediatric B-ALL.

METHODS

A retrospective analysis of 221 consecutive pediatric patients with a diagnosis of B-ALL (blood and/or bone marrow) from 2009 to 2012 was performed to determine an association between Ph+ B-ALL and CD25 expression. A threshold of 25% was used to define positive cases for CD25 expression by flow cytometry.

RESULTS

There were 221 patients with a diagnosis of B-ALL ranging from 2 to 22 years (median, 6 years). Eight (3.6%) B-ALL patients were positive for the Philadelphia chromosome translocation (Ph+ B-ALL) and 213 were negative (Ph-negative B-ALL). CD25 expression was observed in 6 of 8 (75%) Ph+ B-ALL patients and 6 of 213 (2.8%) Ph-negative B-ALL patients. CD25 expression was significantly higher in Ph+ B-ALL compared to Ph-negative B-ALL, with median CD25 expression of 64% (range 0-93%) and 0.1% (range 0-91%), respectively (P ≤ 0.0002). Therefore, CD25 expression as a predictor of Ph+ B-ALL had 75% sensitivity, 97% specificity, 50% positive predictive value and 99% negative predictive value.

CONCLUSIONS

CD25 expression is a specific and relatively sensitive marker for the identification of Ph+ B-ALL in the pediatric population.

Frequency of p190 and p210 BCR-ABL rearrangements and survival in Brazilian adult patients with acute lymphoblastic leukemia

Objective

This study investigated the occurrence of the p190 and p210 breakpoint cluster region-Abelson (BCR-ABL) rearrangements in adults with acute lymphoblastic leukemia and possible associations with clinical and laboratory characteristics and survival.

Methods

Forty-one over 18-year-old patients with acute lymphoblastic leukemia of both genders followed-up between January 2008 and May 2012 were included in this study. Clinical and laboratory data were obtained from the medical charts of the patients. Reverse transcription polymerase chain reaction (RT-PCR) using specific primers was employed to identify molecular rearrangements.

Results

At diagnosis, the median age was 33 years, and there was a predominance of males (61%). The most common immunophenotype was B lineage (76%). BCR-ABL rearrangements was detected in 14 (34%) patients with the following distribution: p190 (28%), p210 (50%) and double positive (22%). Overall survival of patients with a mean/median of 331/246 days of follow up was 39%, respectively, negative BCR-ABL (44%) and positive BCR-ABL (28%).

Conclusion

These results confirm the high frequency of BCR-ABL rearrangements and the low survival rate of adult Brazilian patients with acute lymphoblastic leukemia.

B acute lymphoblastic leukemia with t(14;19)(q32;p13.1) involving IGH/EPOR: a clinically aggressive subset of disease

B acute lymphoblastic leukemia (B-ALL) with t(14;19)(q32;p13.1), in which IGH and EPOR are juxtaposed, has been reported rarely. We describe the clinicopathological features of six patients, three men and three women, with a median age of 39 years. Initial and follow-up bone marrow samples were examined from each patient. The clinical, morphologic, and immunophenotypic results were compared with data obtained from conventional cytogenetic analysis and by using home-brew fluorescence in situ hybridization (FISH) probes for IGH at 14q32 and EPOR at 19p13.1. The bone marrow specimens were hypercellular (median 90%; range 80-100%), with a median blast count of 90% (range 60-93%). Immunophenotypic analysis performed by flow cytometry demonstrated a stable, precursor B-cell immunophenotype. The t(14;19)(q32;p13.1) was present in all cases with morphologic evidence of disease. The translocation was stable and appeared morphologically subtle on conventional karyotypic analysis. Detection was facilitated using FISH, which confirmed IGH/EPOR rearrangement in all cases. All patients received aggressive multiagent chemotherapy as part of a variety of regimens. Four of six patients achieved an initial complete remission, but all relapsed. At last follow-up, five of six patients had died of disease (median survival, 12 months after diagnosis). We conclude that B-ALL associated with t(14;19)(q32;p13.1) is a distinctive form of disease that is associated with younger patient age and an aggressive clinical course.

Impact of minimal residual disease kinetics during imatinib-based treatment on transplantation outcome in Philadelphia chromosome-positive acute lymphoblastic leukemia

We conducted a systemic evaluation to describe the effect of minimal residual disease (MRD) kinetics on long-term allogeneic transplantation outcome by analyzing 95 adult transplants with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL) who received first-line two courses of imatinib-based chemotherapy (median follow-up 5 years). MRD monitoring was centrally evaluated by real-time quantitative PCR (4.5 log sensitivity). After the first course of imatinib-based chemotherapy, 33 patients (34.7%) achieved at least major molecular response. On the basis of MRD kinetics by the end of two courses of imatinib-based chemotherapy, we stratified entire patients into four subgroups: early-stable molecular responders (EMRs, n=33), late molecular responders (LMRs, n=35), intermediate molecular responders (IMRs, n=9) and poor molecular responders (PMRs, n=18). Multivariate analysis showed that the most powerful factor affecting long-term transplantation outcome was MRD kinetics. Compared with EMRs, IMRs or PMRs had significantly higher risk of treatment failure in terms of relapse and disease-free survival (DFS). LMRs had a tendency toward a lower DFS. Quantitative monitoring of MRD kinetics during the first-line imatinib-based chemotherapy course is useful in identifying subgroups of Ph-positive ALL transplants at a high risk of relapse.

Precursor B-acute lymphoblastic leukemia occurring in patients with a history of prior malignancies: is it therapy-related?

BACKGROUND

Precursor B-acute lymphoblastic leukemia occurring in patients with a history of malignancies is uncommon, and this condition is not well understood.

DESIGN AND METHODS

A retrospective review of 457 adults with precursor B-acute lymphoblastic leukemia treated at our hospital identified 44 (9.6%) patients with prior malignancies. The clinical and genetic characteristics of this group of patients was compared with those of their counterparts with de novo disease and the relationship with prior chemoradiation therapy was assessed.

RESULTS

Thirty of 44(6.2%) patients received cytotoxic therapies, whereas 14 patients did not. The former group showed a significantly shorter interval from prior malignancy to onset of precursor B-acute lymphoblastic leukemia (36 versus 144 months; P = 0.002). Compared with 413 de novo cases, the frequencies of t(4;11)(q21;q23) (P<0.001) and hypodiploidy (P = 0.009) with loss of chromosome 5, 7 or 17 were significantly higher in patients who received topoisomerase II inhibitor and/or alkylating agents. By contrast, Philadelphia-positive and normal karyotype were more frequent in patients who either did not receive chemotherapy or received only local radiation or nucleoside analogs. Patients with precursor B-acute lymphoblastic leukemia following prior malignancies and chemoradiation were older, had a lower complete remission rate and showed an inferior survival in univariate, but not multivariate analysis.

CONCLUSIONS

The data support the interpretation that therapy-related precursor B-acute lymphoblastic leukemia does occur. In particular, cases associated with t(4;11)(q21;q23) or hypodiploidy with -5, -7, -17 are likely to be therapy-related and have a poor prognosis. The inferior outcome of these patients may be attributable to the high-risk cytogenetic abnormalities that are found in this group of patients.

Advances in acute lymphoblastic leukemia in adults

PURPOSE OF REVIEW

This review will be focused on the advances in adult acute lymphoblastic leukemia (ALL) based on recently published articles.

RECENT FINDINGS

Progress in the understanding of the molecular basis of ALL has contributed to a more precise definition of risk factors. The study of minimal residual disease has re-defined the baseline prognostic factors and has opened new strategies for postremission management. The use of pediatric-inspired therapies for young adults with standard-risk ALL, the broadening of the number of patients who are eligible for allogeneic stem cell transplantation, the increasing use of targeted therapies (monoclonal antibodies, tyrosine kinase inhibitors, and new purine analogs, etc.) in early phases of the disease, together with the improvements in supportive therapy explain the increased survival of young and middle-aged adult ALL.

SUMMARY

These changes are improving long-term outcome, which in ongoing studies is expected to be of close to 50%, and are opening the door for future therapeutic advances.

Bmi1 reprograms CML B-lymphoid progenitors to become B-ALL-initiating cells

The characterization and targeting of Philadelphia chromosome positive (Ph(+)) acute lymphoblastic leukemia (ALL)-initiating cells remains unresolved. Expression of the polycomb protein Bmi1 is up-regulated in patients with advanced stages of chronic myelogenous leukemia (CML). We report that Bmi1 transforms and reprograms CML B-lymphoid progenitors into stem cell leukemia (Scl) promoter-driven, self-renewing, leukemia-initiating cells to result in B-lymphoid leukemia (B-ALL) in vivo. In vitro, highly proliferating and serially replatable myeloid and lymphoid colony-forming cultures could be established from BCR-ABL and Bmi1 coexpressing progenitors. However, unlike in vivo expanded CML B-lymphoid progenitors, hematopoietic stem cells, or multipotent progenitors, coexpressing BCR-ABL and Bmi1 did not initiate or propagate leukemia in a limiting dilution assay. Inducible genetic attenuation of BCR-ABL reversed Bmi1-driven B-ALL development, which was accompanied by induction of apoptosis of leukemic B-lymphoid progenitors and by long-term animal survival, suggesting that BCR-ABL is required to maintain B-ALL and that BCR-ABL and Bmi1 cooperate toward blast transformation in vivo. Our data indicate that BCR-ABL targeting itself is required to eradicate Ph(+)/Bmi1(+) B-ALL-initiating cells and confirm their addiction to BCR-ABL signaling.

Acute lymphoblastic leukemia of adulthood: progress or not?

OPINION STATEMENT

Much new information about ALL in adults has recently been learned from major clinical and laboratory studies. However, much of the recently reported improved management of this leukemia pertains only to younger patients. Elderly patients do not fair very well with modern therapy, including intensified treatment approaches. The question arises whether current treatment may be unnecessarily intensive, not only for elderly patients but for most patients. There are no prospective, randomized studies that clearly demonstrate that anthracyclines, cyclophosphamide or cytarabine are required for optimal results in this leukemia. Eliminating drugs of marginal value but with the potential for considerable toxicity may allow us to intensify treatment with drugs that are most effective at a cost of even less toxicity than usually expected.