Aberrant myeloid marker expression in precursor B-cell and T-cell leukemias

Aggressive Mediastinal Lymphomas

The mediastinum contains essentially all major intrathoracic organs except for the lungs. A variety of both benign and malignant tumors can involve the mediastinum, of which lymphoma is the most common malignancy. Compared to secondary mediastinal involvement by systemic lymphomas, primary mediastinal lymphomas are less common with several specific entities that are mainly confined to mediastinal lymph nodes, and/or thymus. This review will summarize the clinical, histologic, immunophenotypic and molecular genetic features of the most common and most aggressive primary mediastinal lymphomas as well as provide suggested immunohistochemistry panels and differential diagnoses.

CAR-T cell therapy in T-cell malignancies: Is success a low-hanging fruit?

Chimeric antigen receptor T-cell (CAR-T) therapy has been prosperous in the treatment of patients with various types of relapsed/refractory (R/R) B-cell malignancies including diffuse large B-cell lymphoma (DLBCL), B-cell acute lymphoblastic leukemia (B-ALL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and multiple myeloma (MM). However, this type of therapy has faced serious hindrances in combating T-cell neoplasms. R/R T-cell malignancies are generally associated with poor clinical outcomes, and the available effective treatment approaches are very limited. CAR-T therapy of T-cell malignancies has unique impediments in comparison with that of B-cell malignancies. Fratricide, T-cell aplasia, and product contamination with malignant T cells when producing autologous CAR-Ts are the most important challenges of CAR-T therapy in T-cell malignancies necessitating in-depth investigations. Herein, we highlight the preclinical and clinical efforts made for addressing these drawbacks and also review additional potent stratagems that could improve CAR-T therapy in T-cell malignancies.

CAR-T cell therapy in T-cell malignancies: Is success a low-hanging fruit?

Chimeric antigen receptor T-cell (CAR-T) therapy has been prosperous in the treatment of patients with various types of relapsed/refractory (R/R) B-cell malignancies including diffuse large B-cell lymphoma (DLBCL), B-cell acute lymphoblastic leukemia (B-ALL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and multiple myeloma (MM). However, this type of therapy has faced serious hindrances in combating T-cell neoplasms. R/R T-cell malignancies are generally associated with poor clinical outcomes, and the available effective treatment approaches are very limited. CAR-T therapy of T-cell malignancies has unique impediments in comparison with that of B-cell malignancies. Fratricide, T-cell aplasia, and product contamination with malignant T cells when producing autologous CAR-Ts are the most important challenges of CAR-T therapy in T-cell malignancies necessitating in-depth investigations. Herein, we highlight the preclinical and clinical efforts made for addressing these drawbacks and also review additional potent stratagems that could improve CAR-T therapy in T-cell malignancies.

What is the Role of Hematopoietic Cell Transplantation (HCT) for Pediatric Acute Lymphoblastic Leukemia (ALL) in the Age of Chimeric Antigen Receptor T-Cell (CART) Therapy?

CD19 chimeric antigen receptor T-cell (CART) therapy has revolutionized the treatment of patients with relapsed/refractory hematologic malignancies, especially B-cell acute lymphoblastic leukemia. As CART immunotherapy expands from clinical trials to FDA-approved treatments, a consensus among oncologists and hematopoietic cell transplant (HCT) physicians is needed to identify which patients may benefit from consolidative HCT post-CART therapy. Here, we review CD19 CART therapy and the outcomes of published clinical trials, highlighting the use of post-CART HCT and the pattern of relapse after CD19 CART. At this time, the limited available long-term data from clinical trials precludes us from making definitive HCT recommendations. However, based on currently available data, we propose that consolidative HCT post-CART therapy be considered for all HCT-eligible patients and especially for pediatric patients with KMT2A-rearranged B-cell acute lymphoblastic leukemia.

Chimeric antigen receptor transduced T cells: Tuning up for the next generation

Chimeric antigen receptor (CAR) T cell therapy has recently achieved impressive clinical outcome in patients with CD19-positive hematologic malignancies. Extrapolation of CAR T cell treatment to solid tumors, however, has not yet yielded similar results. This might be due to intrinsic causes, e.g. insufficient CAR T cell activation or CAR toxicity as well as extrinsic factors displaying an unfavorable tumor environment for CAR T cells by raising physical and chemical barriers. In this review, we discuss the advantages as well as major obstacles of CAR T cell therapy, particularly in the context of solid tumors, and focus on efforts and novel strategies in CAR T cell development.

CRISPR-Cas9-induced t(11;19)/MLL-ENL translocations initiate leukemia in human hematopoietic progenitor cells in vivo

Chromosomal translocations that generate oncogenic fusion proteins are causative for most pediatric leukemias and frequently affect the MLL/KMT2A gene. In vivo modeling of bona fide chromosomal translocations in human hematopoietic stem and progenitor cells is challenging but essential to determine their actual leukemogenic potential. We therefore developed an advanced lentiviral CRISPR-Cas9 vector that efficiently transduced human CD34⁺ hematopoietic stem and progenitor cells and induced the t(11;19)/MLL-ENL translocation. Leveraging this system, we could demonstrate that hematopoietic stem and progenitor cells harboring the translocation showed only a transient clonal growth advantage in vitro In contrast, t(11;19)/MLL-ENL-harboring CD34⁺ hematopoietic stem and progenitor cells not only showed long-term engraftment in primary immunodeficient recipients, but t(11;19)/MLL-ENL also served as a first hit to initiate a monocytic leukemia-like disease. Interestingly, secondary recipients developed acute lymphoblastic leukemia with incomplete penetrance. These findings indicate that environmental cues not only contribute to the disease phenotype, but also to t(11;19)/MLL-ENL-mediated oncogenic transformation itself. Thus, by investigating the true chromosomal t(11;19) rearrangement in its natural genomic context, our study emphasizes the importance of environmental cues for the pathogenesis of pediatric leukemias, opening an avenue for novel treatment options.

Acute leukemia in six horses (1990-2012)

Acute leukemia is rare in horses. Herein we describe historical, clinicopathologic, and postmortem findings in 6 horses with acute leukemia. Medical records of horses with >20% bone marrow blasts and cytochemical or immunophenotyping results were reviewed. Affected horses were 2-8 y of age and of different breeds and sex. Horses were presented acutely with nonspecific signs (e.g., fever, lethargy). Characteristic hemogram findings were bi- or pancytopenia with low blast numbers. Histologic examination revealed extramedullary infiltrates, especially in lymph nodes, spleen, kidney, liver, and lungs. Leukemias were classified as B-cell ( n = 3) and acute myeloid leukemia (AML) ( n = 3). Tumors in 4 cases expressed multiple lineage markers, which complicated classification. Acute leukemia should be suspected in horses with moderate-to-severe bi- or pancytopenia. Blood smears should be reviewed for neoplastic cells, and bone marrow examination is required for diagnosis. Leukemia classification is best achieved using combined morphologic, cytochemical, and immunophenotyping results.

Female Genital Tract Involvement in Acute Lymphoblastic Leukemia: A Rare Case Report

Female Genital Tract (FGT) involvement with hematologic neoplasms is uncommon and the hematologic malignancies which involve the female genital organs are usually non-Hodgkin's lymphoma. Involvement of the uterus and cervix with Acute Lymphoblastic Leukaemia (ALL) is extremely rare, and ovarian involvement is even rarer. We report the case of a young lady who presented with tubo-ovarian mass, excessive post-operative bleeding (post-total abdominal hystrerctomy and bilateral salpingo-oophorectomy) and was diagnosed to have ALL with blood and tissue involvement by histopathology and flow cytometry.

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.

Expression of CD56 is a risk factor for acute lymphocytic leukemia with central nervous system involvement in adults

OBJECTIVE

To gain further insights into the predisposing risk factors for central nervous system (CNS) involvement in patients with acute lymphocytic leukemia (ALL), the impact of CD56 expression in these patients was investigated.

METHODS

We reviewed the clinical features of CD56 expression in 588 consecutive ALL patients treated with systemic chemotherapy regimens between 2000 and 2014. The categorical data from CD56⁺ ALL patients were compared with those from CD56^- ALL patients.

RESULTS

Among the 588 patients studied, 18.9% showed CD56 expression. The expression was significantly associated with CD33⁺, CD10^-, CD15⁺, TdT^-, and CD5⁺ immunophenotypes. After systemic chemotherapy, 8.8% patients showed CNS involvement, of which 3.2% exhibited combined recurrences and 5.6% exhibited isolated CNS involvement. The 5-year event-free survival was significantly lower for patients with CD56⁺ immunophenotype compared with patients with CD56^- immunophenotype (22.5% vs. 32.7%, P = 0.04). Cumulative incidences of CNS involvement were significantly greater in the CD56⁺ cohort compared with the CD56^- cohort (14.4% vs. 7.5%, P = 0.02). Multivariate analysis revealed CD56 expression to be statistically significant risk factors for CNS involvement.

CONCLUSION

CD56 expression should be regarded as an independent risk factor for ALL with CNS involvement in adults.

Chimeric Antigen Receptor T Cell Therapy Targeting CD19-Positive Leukemia and Lymphoma in the Context of Stem Cell Transplantation

Novel therapies with chimeric antigen receptor (CAR)-transduced T cells (TCs) sparked new hope for patients with relapsed or refractory CD19-positive leukemia or lymphoma even after stem cell therapies. This review focuses on CARs recognizing the B cell antigen CD19. Both retroviral and lentiviral vectors are used, encoding various anti-CD19 CAR constructs comprising costimulatory molecules such as CD28, CD137/4-1BB, and OX40 either alone (second-generation CARs) or in combination (third-generation CARs). Current, up-to-date published studies on anti-CD19 CAR therapy for acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL) with observed side effects are discussed and an outlook on 58 ongoing trials is given. Clinical responses were achieved in up to 81% of ALL, 50% of CLL, and 40% of NHL patients. Factors with potential influence on the clinical outcome might be the design of the vector, the preconditioning regimen, and the number and quality of transfused CAR TCs. The applicability of clinical CAR TC therapy might include relapse after allogeneic stem cell transplantation (alloSCT), and ineligibility for or "bridging" until alloSCT. In summary, CAR therapy represents a highly promising treatment option even in heavily pretreated patients.

Context Matters: Distinct Disease Outcomes as a Result of Crebbp Hemizygosity in Different Mouse Bone Marrow Compartments

Perturbations in CREB binding protein (CREBBP) are associated with hematopoietic malignancies, including myelodysplastic syndrome (MDS). Mice hemizygous for Crebbp develop myelodysplasia with proliferative features, reminiscent of human MDS/myeloproliferative neoplasm-unclassifiable (MDS/MPN-U), and a proportion goes on to develop acute myeloid leukemia (AML). We have also shown that the Crebbp+/- non-hematopoietic bone marrow microenvironment induces excessive myeloproliferation of wild-type cells. We now report that transplantation of unfractionated Crebbp+/- bone marrow into wild-type recipients resulted in either early-onset AML or late-onset MDS and MDS/MPN-U. In contrast, purified Lin-Sca-1+c-Kit++ cells primarily gave rise to MDS with occasional transformation to AML. Furthermore, Crebbp+/- common myeloid progenitors and granulocyte/macrophage progenitors could trigger skewed myelopoiesis, myelodysplasia and late-onset AML. Surprisingly, the phenotypically abnormal cells were all of wild-type origin. MDS, MPN and AML can thus all be transferred from Crebbp+/- BM to wild-type hosts but fractionated bone marrow does not recapitulate the full disease spectrum of whole bone marrow, indicating that not only mutational status but also cellular context contribute to disease outcome. This has important consequences for structuring and interpreting future investigations into the underlying mechanisms of myeloid malignancies as well as for their treatment.

T-cell acute lymphoblastic leukemia with co-expression of CD56, CD34, CD117 and CD33: A case with poor prognosis

T-cell acute lymphoblastic leukemia (ALL) is an aggressive hematological malignancy, accounting for ~25% of all adult cases of ALL. We herein report a case of T-cell ALL exhibiting aberrant CD34, CD56, CD33 and CD117 expression in addition to T-cell markers, which did not respond to induction treatment. A 55-year-old woman was admitted to our hospital with a sore throat unresponsive to medication for 1 month. The laboratory examination revealed pancytopenia and the peripheral blood smear examination revealed blast cells. On flow cytometric analysis, the blast cells were found to be positive for cytoplasmic CD3, CD2, CD5, CD7, CD34, CD56, CD33 and CD117, and negative for myeloperoxidase, CD13, CD11b, CD15, CD19, CD79a, CD22 and CD10. The patient was diagnosed with T-cell ALL according to the 2008 World Health Organisation classification. The patient did not respond to Hyper-cyclophosphamide, vincristine, adriamycin and dexamethasone (CVAD) course A treatment and succumbed to the disease during Hyper-CVAD course B treatment. To the best of our knowledge, this is the first report of aberrant co-expression of the natural killer cell marker CD56, myeloid cell markers CD117 and CD33 and stem cell marker CD34 in a patient with T-cell ALL. This appears to be associated with an unfavorable outcome, despite the use of intensive chemotherapy.

CD19: A multifunctional immunological target molecule and its implications for Blineage acute lymphoblastic leukemia

Over the last 20-30 years CD19 has gained attention as a potential target in the therapy of B-cell malignancies. In particular, targeting CD19 with the bispecific T-cell engager (BiTE) antibody Blinatumomab and T-cells modified by chimeric antigen receptors (CAR) has shown promising efficacy in early phase clinical trials for adults and children with precursor B-cell ALL (BCP-ALL). This review will discuss the rationale behind targeting CD19 in BCP-ALL and its potential importance in BCP-ALL signaling pathways.

Beyond CD19: Opportunities for Future Development of Targeted Immunotherapy in Pediatric Relapsed-Refractory Acute Leukemia

Chimeric antigen receptor (CAR) T cell therapy has been used as a targeted approach in cancer therapy. Relapsed and refractory acute leukemia in pediatrics has been difficult to treat with conventional therapy due to dose-limiting toxicities. With the recent success of CD 19 CAR in pediatric patients with B cell acute lymphoblastic leukemia (ALL), this mode of therapy has become a very attractive option for these patients with high-risk disease. In this review, we will discuss current treatment paradigms of pediatric acute leukemia and potential therapeutic targets for additional high-risk populations, including T cell ALL, AML, and infant ALL.

T-cell acute lymphoid leukemia resembling Burkitt leukemia cell morphology: A case report

Biphenotypic acute leukemia (BAL) is an uncommon type of cancer, which accounts for <5% of all adult ALs. Based upon a previously described scoring system, the European Group for the Immunological Classification of Leukemias (EGIL) proposed a set of diagnostic criteria for BAL. This scoring system is based upon the number and degree of specificity of several markers for myeloid or T/B-lymphoid blasts. The present study describes a case of T-cell acute lymphoblastic leukemia (T-ALL) with Burkitt-like cytology, which according to the French-American-British classification, corresponded to a diagnosis of Burkitt type L3 ALL. Flow cytometry analysis demonstrated that the blasts were positive for T-lymphoid markers, cytoplasmic cluster of differentiation (CD)3, CD7 and CD56, and myeloid markers, CD13, CD33 and CD15. At first, a diagnosis of BAL was suggested by the EGIL score, however, according to the 2008 World Health Organization criteria, a case of T-ALL with aberrant myeloid markers was established. The study also reviewed the literature and discussed the limitations of the EGIL scoring system in clinical decision making, to aid in the selection of an appropriate therapeutic regimen.

Immunophenotypic, Cytogenetic and Clinical Features in Chinese Adult Acute Lymphoblastic Leukaemia (ALL) Patients

Introduction: This study sought to investigate the immunophenotypic subtype profiles of 110 Chinese adult patients with acute lymphoblastic leukaemia (ALL) and its association to cytogenetics and the clinical features. Materials and Methods: A total of 110 adult patients with ALL were immunophenotyped by CD45/SSC double parameters and 4 colour flow cytometry. Seventy-three cases were also subjected to karyotype analysis by R-banding technology. The clinical and laboratory data of 110 ALL patients were retrospectively analysed. Results: Of all the patients, 21.8% were identified as T-ALL, 78.2% as B-ALL. Abnormal karyotypes were detected in 37 out of 73 (50.7%) cases and the most common cytogenetic abnormality was the Philadelphia (Ph) chromosome, which was found in 23.3% (17/73) of the cases. Myeloid antigen (MyAg) expression was documented in 47.3% of the 110 adult ALL cases analysed and CD13 was the most commonly expressed MyAg in ALL patients (32.1 %). No difference was observed in the expression of MyAg between the groups of patients with T-ALL (45.8%) and B-ALL (47.7%). Our data showed that older age, higher CD34 positivity and lower proportion of patients with splenomegaly were found to be correlated with MyAg+ ALL, and that patients with Ph+ B-ALL were older, presented with higher haemoglobin level and higher CD34 expression. No statistical difference was noted in complete remission (CR) rate, relapse rate, induction mortality or total death rate among My+ and My-, Ph+ and Ph-, or B-ALL and T-ALL patients. Conclusion: Our results indicate that the distribution of ALL in Chinese adult patients was similar with the general distribution pattern in the other countries, and the expression of MyAg in patients with T-ALL and B-ALL was comparable. Both the expression of MyAg and the presence of Ph chromosome in adult ALL were significantly associated with median age and CD34 expression while not with the response to induction treatment. Key words: Biological characteristics, Cytogenetics, Immunophenotype

Expression of myeloid antigens on lymphoblast surface in childhood acute lymphoblastic leukemia at diagnosis and its effect on early response to treatment: a preliminary report

Immunodiagnosis of acute lymphoblastic leukemia (ALL) is based on the assessment of surface antigens. There are also cases in which both lymphoid and myeloid antigens can be found on the surface of lymphoblasts. The purpose of our research was to assess the expression of myeloid and lymphoblastic antigens in children with ALL, and to determine the impact of surface antigens on early response to treatment. 58 children [33 girls (56.9 %), 25 boys (43.2 %)] with ALL were studied. Response to treatment was assessed on days 8, 15, and 33. Univariate logistic regression analysis of the effect of myeloid antigens (MyAg) on response to treatment on days 8 and 33 revealed expression of any MyAg on lymphoblast surface as a factor associated with poor response to treatment. The multivariate logistic regression analysis of treatment response on day 33, showed that the expression of CD13 antigen on lymphoblast surface is a key factor affecting delayed remission (p = 0.03; odds ratio 0.12; 95 % CI 0.01-0.81). The expression of MyAg in childhood ALL adversely affects early response to treatment. The expression of CD13 antigen on day 33 is a key factor affecting complete remission in ALL patients.

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.

Characteristics of CD5-positive splenic marginal zone lymphoma with leukemic manifestation ; clinical, flow cytometry, and histopathological findings of 11 cases

Splenic marginal zone lymphoma (SP-MZL) is a rare low-grade B-cell neoplasm that often shows leukemic manifestation. Less than 20% of cases of SP-MZL express CD5. We analyzed 11 cases of CD5-positive SP-MZL with leukemic manifestation. The clinical characteristics of these cases did not differ from those of CD5-negative SP-MZL. Flow cytometry revealed positive results as follows : CD3, 0/9 ; CD5, 11/11 ; CD10, 0/11 ; CD11c, 4/10, CD13, 5/11 ; CD19, 11/11 ; CD20, 10/11 ; CD21, 4/4 ; CD22, 7/7 ; CD23, 5/10 ; CD25, 8/11 ; FMC7, 5/7 ; κ type 6/9, and λ type 2/9. All 3 cases with monoclonal γ-globulinemia expressed CD13. Resected spleen exhibited a proliferation of neoplastic cells in white pulp in all 8 splenectomy patients and a marginal pattern was detected in 5 patients. Only 2 cases showed involvement of red pulp. Immunohistochemistry showed that the lymphoma cells were positive for CD5, CD20, and BCL-2 and negative for CD3, CD10, cyclin D1, BCL-6, and MUM-1 in all 11 cases. These results suggest that CD5-positive SP-MZL differs from B-cell chronic lymphocytic leukemia, that CD13 expression is found in about half of CD5-positive SP-MZL cases, and that CD5-positive SP-MZL may be related to memory B-cell neoplasm or plasma cell differentiation.

Characterization of immunophenotypic aberrancies in 200 cases of B acute lymphoblastic leukemia

Morphologic distinction of leukemic lymphoblasts in B acute lymphoblastic leukemia (B-ALL) from their nonneoplastic counterparts in bone marrow (hematogones) can be difficult. Thus, the presence of aberrant antigen expression detectable by flow cytometry may be critical for diagnosis of B-ALL and detection of minimal residual disease. The current study examined the immunophenotype of B-lineage leukemic lymphoblasts in 200 consecutive, unique, pretreatment patient specimens. We found that all cases of B-ALL exhibited multiple immunophenotypic aberrancies by which they can be distinguished from hematogones. The most frequent aberrancies were uniform or a spectrum of expression of terminal deoxynucleotidyl transferase and CD34, underexpression of CD45, overexpression of CD10, underexpression of CD38, and underexpression of CD20. Asynchronous coexpression of CD34 and CD20 was also frequently observed. Of the 200 cases, 86.5% expressed myeloid-associated antigens, and 19.0% expressed 3 or more. Of 200 cases, 9.0% aberrantly expressed T cell-associated antigens. There were significant differences in antigen-expression patterns between adult and pediatric B-ALL. Specific aberrancies correlate with recurrent cytogenetic abnormalities in B-ALL.