Absence of terminal deoxynucleotidyl transferase expression identifies a subset of high-risk adult T-lymphoblastic leukemia/lymphoma

Absence of terminal deoxynucleotidyl transferase expression in T-ALL/LBL accumulates chromosomal abnormalities to induce drug resistance

T-acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is a malignant neoplasm of immature lymphoblasts. Terminal deoxynucleotidyl transferase (TDT) is a template-independent DNA polymerase that plays an essential role in generating diversity for immunoglobulin genes. T-ALL/LBL patients with TDT^- have a worse prognosis. However, how TDT^- promotes the disease progression of T-ALL/LBL remains unknown. Here we analyzed the prognosis of T-ALL/LBL patients in Shanghai Children's Medical Center (SCMC) and confirmed that TDT^- patients had a higher rate of recurrence and remission failure and worse outcomes. Cellular experiments demonstrated that TDT was involved in DNA damage repair. TDT knockout delayed DNA repair, arrested the cell cycle and decreased apoptosis to induce the accumulation of chromosomal abnormalities and tolerance to abnormal karyotypes. Our study demonstrated that the poor outcomes in TDT^- T-ALL/LBL might be due to the drug resistance (VP16 and MTX) induced by chromosomal abnormalities. Our findings revealed novel functions and mechanisms of TDT in T-ALL/LBL and supported that hematopoietic stem cell transplantation (HSCT) might be a better choice for these patients.

Mature Type T-Lymphoblastic Leukemia/Lymphoma Presenting With Isolated Central Nervous System Symptomatology in a Patient With Giant Cell Arteritis on Long-Term Steroid Treatment

T-lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) is a malignancy comprised of T-lymphoblasts that can present as one of four clinical subtypes (pro-T, pre-T, cortical T, and mature T). Clinical presentation is typically characterized by leukocytosis with diffuse lymphadenopathy and/or hepatosplenomegaly. Beyond clinical presentation, specific immunophenotypic and cytogenetic classifications are utilized to diagnose mature T-ALL. In later disease stages it can spread to the central nervous system (CNS); however, presentation of mature T-ALL by way of CNS pathology and clinical symptomatology alone is rare. Even more rare is the presence of poor prognostic factors without correlating significant clinical presentation. We present a case of mature T-ALL in an elderly female with isolated CNS symptoms in combination with poor prognostic factors including terminal deoxynucleotidyl transferase (TdT) negativity and a complex karyotype. Our patient lacked the classical symptomatology and laboratory findings of mature T-ALL but deteriorated quickly upon diagnosis due to the aggressive genetic profile of her cancer.

Imaging flow cytometry reveals a subset of TdT negative T-ALL blasts with very low forward scatter on conventional flow cytometry

BACKGROUND

Studies in T-cell acute lymphoblastic leukemia (T-ALL) have shown that leukemic blast populations may display immunophenotypic heterogeneity. In the clinical setting, evaluation of measurable residual disease during treatment and follow-up is highly dependent on knowledge of the diversity of blast subsets. Here, we set out to evaluate whether variation in expression of the blast marker, TdT, in T-ALL blasts could correspond to differences in morphometric features.

METHODS

We investigated diagnostic bone marrow samples from six individual T-ALL patients run in parallel on imaging flow cytometry (IFC) and conventional flow cytometry (CFC).

RESULTS

Guided by the imagery available in IFC, we identified distinct TdT^neg and TdT^pos subpopulations with apparent differences in internal complexity. As TdT^neg blasts predominantly displayed very low forward scatter (FSC) on CFC, these subsets were initially excluded from routine analysis as debris, elements of small diameter, apoptotic, and/or dead cells. However, IFC-based morphometric analyses demonstrated that cell size and shape of TdT^neg blasts were comparable to the TdT^pos cells and without morphometric apoptotic hallmarks, supporting that the TdT^neg subpopulation corresponded to T-ALL blasts. Fluorescence in situ hybridization analyses substantiated the clinical relevance of TdT^neg FSC^very-low cells by retrieving known diagnostic cytogenetic abnormalities at comparable frequencies in purified TdT^neg FSC^very-low and TdT^pos FSC^int subsets.

CONCLUSION

We highlight this finding as knowledge of phenotypic heterogeneity is of crucial importance in the clinical setting for delineation and quantification of blast subpopulations of potential biological relevance. We argue that the IFC imagery may allow for visual verification and improvement of applied gating strategies.

A New Treatment Strategy for Early T-Cell Precursor Acute Lymphoblastic Leukemia: A Case Report and Literature Review

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is an aggressive and extremely fatal subtype of T-cell acute lymphoblastic leukemia (T-ALL), characterized by the similar transcriptional and immunophenotypic profiles to those of early T-cell precursors and positive expressions of myeloid antigens. Besides, the gene expression profile in ETP-ALL is similar to that in myeloid malignancies. The clinical characteristics, treatments and prognoses of ETP-ALL are significantly heterogeneous. In the present study, we reported a 43-year-old female patient who lacked terminal deoxynucleotidyl transferase (TDT) expression in immunophenotype and displayed mutations of fms-like tyrosine kinase-internal tandem duplication (FLT3-ITD), paired-box domain 5 (PAX5) and SH2B adaptor protein 3 (SH2B3) (PAX5 and SH2B3, the genes critical to B cell identity and function), which represent myeloid and precursor B-lineage associated gene mutations, respectively. It was a rare T-ALL or T-lineage case. Because of multiple poor prognostic factors in this case, conventional induction regimens, like hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, dexamethasone), were invalid. The patient showed inadequate response, suggesting that this treatment was not employed on the basis of the immunophenotype. FLAG-IDA regimen (fludarabine, cytarabine [Ara-C], granulocyte-colony stimulating factor [G-CSF] and idarubicin), which is usually applied to eliminate leukemia cells, was administered combining with sorafenib as an effective induction chemotherapy. The case achieved long-term survival following the allogeneic hematopoietic stem cell transplantation (allo-HSCT). We recommend that adult ETP-ALL patients can be treated with a myeloid-oriented chemotherapy (as frontline induction treatment) along with gene-targeting inhibitors, followed by allo-HSCT.

SET-NUP214 Fusion Gene Involved Early T-Cell Precursor Acute Lymphoblastic Leukemia in Adult with B Marker Expression

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is rare and associated with poor clinical outcome especially in adults. ETP tumor cells that express cross-lineage antigens or lack pan T markers usually pose big challenges to diagnosis, and their prognostic implications are therefore more uncertain. This study reports the unique case of a 44-year-old woman with breast mass as the initial presentation of acute leukemia possessing both T- and B-cell features (cytoplasmic CD3⁺CD7⁺CD19⁺CD79a⁺). Despite the presence of gene rearrangements of IGH and IGK probably in a small amount of B cells, the patient was diagnosed with T-ALL mainly according to WHO criteria, and further ETP-ALL rather than mixed phenotype ALL based on additional positive expression of stem/myeloid lineage antigens (CD34⁺CD13⁺CD33⁺HLA-DR⁺). Moreover, in spite of normal karyotype, SET-NUP214 gene fusion is identified, which has not been described in ETP-ALL with bi-phenotype. After intensive chemotherapy, the patient achieved short-term morphologic complete remission but relapsed within one month. This report may expand immunophenotype and clinical behavior of ETP-ALL in adults. Comprehensive evaluations are emphasized in making a differential diagnosis and distinguishing subtypes of acute leukemia.

Drug Resistance Biomarkers and Their Clinical Applications in Childhood Acute Lymphoblastic Leukemia

Biomarkers are biological molecules found in body fluids or tissues, which can be considered as indications of a normal or abnormal process, or of a condition or disease. There are various types of biomarkers based on their application and molecular alterations. Treatment-sensitivity or drug resistance biomarkers include prognostic and predictive molecules with utmost importance in selecting appropriate treatment protocols and improving survival rates. Acute lymphoblastic leukemia (ALL) is the most prevalent hematological malignancy diagnosed in children with nearly 80% cure rate. Despite the favorable survival rates of childhood ALL (chALL), resistance to chemotherapeutic agents and, as a consequence, a dismal prognosis develops in a significant number of patients. Therefore, there are urgent needs to have robust, sensitive, and disease-specific molecular prognostic and predictive biomarkers, which could allow better risk classification and then better clinical results. In this article, we review the currently known drug resistance biomarkers, including somatic or germ line nucleic acids, epigenetic alterations, protein expressions and metabolic variations. Moreover, biomarkers with potential clinical applications are discussed.

Molecular and phenotypic characterization of an early T-cell precursor acute lymphoblastic lymphoma harboring PICALM-MLLT10 fusion with aberrant expression of B-cell antigens

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is usually diagnosed based on the presence of immature lymphoid marker terminal deoxynucleotidyl transferase (TdT), and T-cell specific markers, specifically CD3, by immunohistochemistry (IHC) staining on bone marrow and/or extramedullary tissue. We present a novel, TdT and CD3 negative, aggressive early T-cell precursor LBL (ETP-LBL) initially misdiagnosed as a high grade B-cell lymphoma due to expression of CD79a and the erroneous detection of BCL2/IGH fusion. The patient was eventually evaluated using molecular diagnostic techniques, including fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) assays that demonstrated PICALM-MLLT10 fusion and a NOTCH1 mutation in the absence of BCL2/IGH fusion. The use of NGS, specifically mate-pair sequencing (MPseq), subsequently confirmed an in-frame PICALM-MLLT10 fusion. Our retrospective analysis showed that PICALM-MLLT10 fusion has no association with CD3/TdT negativity, as 6/49 T-ALL/LBL cases from Mayo Clinic database (01/1998-09/2018), including this case, were noted to have PICALM-MLLT10 fusion; however, none of the other cases were associated with CD3/TdT negativity. We emphasize the importance of a comprehensive hematopathologic evaluation including multiple molecular studies for the appropriate interrogation and classification of a difficult acute leukemia diagnosis, and to prevent potential diagnostic errors of clinical significance.

Time-Delayed Integration-Spectral Flow Cytometer (TDI-SFC) for Low-Abundance-Cell Immunophenotyping

We describe a unique flow cytometer (TDI-SFC) for the immunophenotyping of low-abundance cells, particularly when cell counts are sample-limited and operationally difficult for analysis by fluorescence microscopy (>100 cells) or multiparameter flow cytometry (MFC, <10 000 cells). TDI-SFC combines the high spectral resolution of spectral flow cytometry (SFC) with a CCD operated in time-delayed integration (TDI) for improved duty cycle and sensitivity. Cells were focused with a 1D-sheathing microfluidic device, and fluorescence emission generated from a 488 nm laser was collected by epi-illumination and dispersed along one axis of a CCD by a spectrograph. Along the other axis, the CCD's shift rate was clocked at a rate that closely matched the cells' velocity through the field of view. This TDI-SFC format allowed the CCD shutter to remain open during signal acquisition, providing a duty cycle ∼100% and assurance that ∼95% cells were interrogated. We used fluorescent beads to optimize synchronization of TDI clocking with the sheathed-cell velocity and to improve sensitivity via the excitation intensity, epi-illumination numerical aperture, and integration time. TDI achieved integrated signals of 106 counts at a signal-to-noise ratio (SNR) of 610 for beads corresponding to a load of 4 × 105 antibodies. We also evaluated multiplexing capabilities by spectral deconvolution and undertook a proof-of-concept application to immunophenotype low-abundance cells; the demonstration consisted of immunophenotyping a model cell line, in this case SUP-B15 cells representing B-cell acute lymphoblastic leukemia (B-ALL). The B-ALL cell line was stained against a leukemic marker (terminal deoxynucleotidyl transferase, TdT), and we successfully used spectral unmixing to discriminate TdT(+) cells from TdT(-) cells even at low cell counts (∼100 cells). The TDI-SFC could potentially be used in any application requiring the immunophenotyping of low-abundance cells, such as in monitoring measurable residual disease in acute leukemias following affinity enrichment of circulating leukemia cells from peripheral blood.

Terminal deoxynucleotidyl transferase (TdT)-negative T-cell lymphoblastic lymphoma with loss of the T-cell lineage-specific marker CD3 at relapse: a rare entity with an aggressive outcome

Terminal deoxynucleotidyl transferase (TdT)-negative T-cell lymphoblastic lymphoma is a variant of T-cell lymphoblastic lymphoma/T-cell lymphoblastic leukaemia. TdT is a marker of immaturity expressed in 90%-95% cases of lymphoblastic lymphoma and useful in differentiating it from other mature lymphomas/leukaemias. It has been associated with poorer response to chemotherapy and a more aggressive outcome. Here we present a case of TdT-negative T-cell lymphoblastic lymphoma in a 28-year-old man who presented with superior vena cava syndrome. The patient was treated with hyper-cyclophosphamide,vincristine, Adriamycin, dexamethasone (CVAD), however unfortunately suffered a relapse 1 year later. A unique feature of our case was that on relapse, the patient lost expression of the T-cell lineage-specific marker CD3, which has previously not been reported in association with TdT-negative T-cell lymphoblastic lymphoma. The patient failed to respond to chemotherapy on his relapse and died.

A Rare Case of Spontaneous Remission of Terminal Deoxynucleotidyl Transferase Negative B-acute Lymphoblastic Leukemia

Spontaneous remission of untreated pediatric leukemia is an extremely rare occurrence. The underlying mechanism may be because of an immune-mediated process or increased cortisol production during stress or infection. We describe a rare case of terminal deoxynucleotidyl transferase negative B-acute lymphoblastic leukemia with concurrent infection that went into remission without treatment with chemotherapy or corticosteroids. Though B-acute lymphoblastic leukemia can rarely go into spontaneous remission, these patients require close follow-up as most patients will eventually develop recurrence.

Targeting the PIM protein kinases for the treatment of a T-cell acute lymphoblastic leukemia subset

New approaches are needed for the treatment of patients with T-cell acute lymphoblastic leukemia (T-ALL) who fail to achieve remission with chemotherapy. Analysis of the effects of pan-PIM protein kinase inhibitors on human T-ALL cell lines demonstrated that the sensitive cell lines expressed higher PIM1 protein kinase levels, whereas T-ALL cell lines with NOTCH mutations tended to have lower levels of PIM1 kinase and were insensitive to these inhibitors. NOTCH-mutant cells selected for resistance to gamma secretase inhibitors developed elevated PIM1 kinase levels and increased sensitivity to PIM inhibitors. Gene profiling using a publically available T-ALL dataset demonstrated overexpression of PIM1 in the majority of early T-cell precursor (ETP)-ALLs and a small subset of non-ETP ALL. While the PIM inhibitors blocked growth, they also stimulated ERK and STAT5 phosphorylation, demonstrating that activation of additional signaling pathways occurs with PIM inhibitor treatment. To block these pathways, Ponatinib, a broadly active tyrosine kinase inhibitor (TKI) used to treat chronic myelogenous leukemia, was added to this PIM-inhibitor regimen. The combination of Ponatinib with a PIM inhibitor resulted in synergistic T-ALL growth inhibition and marked apoptotic cell death. Treatment of mice engrafted with human T-ALL with these two agents significantly decreased the tumor burden and improved the survival of treated mice. This dual therapy has the potential to be developed as a novel approach to treat T-ALL with high PIM expression.

Terminal Deoxynucleotidyl Transferase (TdT)-negative Lymphoblastic Leukemia in Pediatric Patients: Incidence and Clinical Significance

Pediatric terminal deoxynucleotidyl tranferase (TdT)-negative precursor B- or T-lymphoblastic leukemia/lymphoma (B-LL and T-LL) cases are rare and their prognostic significance remains controversial. We aimed to determine the frequency of TdT-negative B- and T-LL in the community hospital setting. Between 2005 and 2015, 43 pediatric patients were diagnosed with lymphoblastic leukemia at our institution, of which 6 (14%) were characterized as TdT-negative by flow cytometric analysis. Four of these 6 patients had B-LL and the other 2 had T-LL. Two of the 6 TdT-negative patients also had undetectable CD34 expression by flow cytometry (TdT/CD34 double-negatives). Subsequent paraffin immunohistochemistry confirmed the negative CD34 expression in both cases. By contrast, all the 6 patients had weak TdT-like immunoreactivity in their marrow despite the negative flow cytometric analysis. Furthermore, neither TdT/CD34-negative cases showed myc rearrangement by fluorescent in situ hybridization, ruling out Burkitt leukemia as a differential diagnostic consideration. We conclude that TdT-negative pediatric B- and T-LL cases (especially those that are TdT/CD34 double-negative) may pose diagnostic challenge to hematopathologists, and ancillary studies (paraffin immunohistochemistry to detect TdT and fluorescent in situ hybridization to exclude myc rearrangement) may be instrumental in reaching the correct diagnosis.

The 2015 World Health Organization Classification of Tumors of the Thymus: Continuity and Changes

This overview of the 4th edition of the World Health Organization (WHO) Classification of thymic tumors has two aims. First, to comprehensively list the established and new tumor entities and variants that are described in the new WHO Classification of thymic epithelial tumors, germ cell tumors, lymphomas, dendritic cell and myeloid neoplasms, and soft-tissue tumors of the thymus and mediastinum; second, to highlight major differences in the new WHO Classification that result from the progress that has been made since the 3rd edition in 2004 at immunohistochemical, genetic and conceptual levels. Refined diagnostic criteria for type A, AB, B1-B3 thymomas and thymic squamous cell carcinoma are given, and it is hoped that these criteria will improve the reproducibility of the classification and its clinical relevance. The clinical perspective of the classification has been strengthened by involving experts from radiology, thoracic surgery, and oncology; by incorporating state-of-the-art positron emission tomography/computed tomography images; and by depicting prototypic cytological specimens. This makes the thymus section of the new WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart a valuable tool for pathologists, cytologists, and clinicians alike. The impact of the new WHO Classification on therapeutic decisions is exemplified in this overview for thymic epithelial tumors and mediastinal lymphomas, and future perspectives and challenges are discussed.

Enzymatic polymerization of poly(thymine) for the synthesis of copper nanoparticles with tunable size and their application in enzyme sensing

A bottom-up strategy was developed for the enzyme mediated synthesis of Cu nanoparticles, which showed good sensing performance.

Diagnosis and subclassification of acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a disseminated malignancy of B- or T-lymphoblasts which imposes a rapid and accurate diagnostic process to support an optimal risk-oriented therapy and thus increase the curability rate. The need for a precise diagnostic algorithm is underlined by the awareness that both ALL therapy and related success rates may vary greatly between ALL subsets, from standard chemotherapy in patients with standard-risk ALL, to allotransplantation (SCT) and targeted therapy in high-risk patients and cases expressing suitable biological targets, respectively. This review summarizes how best to identify ALL and the most relevant ALL subsets.