Immunophenotypic analysis of T-acute lymphoblastic leukemia. A CD5-based ETP-ALL perspective of non-ETP T-ALL

Efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation treatment for adolescent and adult Tlymphoblastic leukemia /lymphoma: a large cohort multicenter study in China

T lymphoblastic leukemia /lymphoma (T-ALL/LBL) is a rare and highly aggressive neoplasm of lymphoblasts. We evaluated 195 T-ALL/LBL adolescent and adult patients who received ALL-type chemotherapy alone (chemo,n = 72) or in combination with autologous hematopoietic stem cell transplantation(auto-HSCT,n = 23) or allogeneic hematopoietic stem cell transplantation(allo-HSCT,n = 100) from January 2006 to September 2020 in three Chinese medical centers. 167 (85.6%) patients achieved overall response (ORR) with 138 complete response (CR) patients (70.8%) and 29 partial response (PR) patients (14.8%). Until October 1, 2023, no difference was found in 5-year overall survival (5-OS) and 5-year progression free survival(5-PFS) between allo-HSCT and auto-HSCT (5-OS 57.9% vs. 36.7%, P = 0.139, 5-year PFS 49.4% vs. 28.6%, P = 0.078) for patients who achieved CR, for patients who achieved PR, allo-HSCT recipients had higher 5-OS compared with chemo alone recipients (5-OS 23.8% vs. 0, P = 0.042). For patients undergoing allo-HSCT, minimal residual disease (MRD) negative population showed better 5-OS survival compared with MRD positive patients (67.8% vs. 19.6%, p = 0.000). There were no significant differences between early T-cell precursor (ETP), NON-ETP patients with or without expression of one or more myeloid-associated or stem cell-associated (M/S+) markers (NON-ETP with M/S+, NON-ETP without M/S+) groups in allo-HSCT population for 5-OS. (62.9% vs. 54.5% vs.48.4%, P > 0.05). Notch mutations were more common in patients with non-relapsed/refractory disease than relapsed/refractory disease (χ² =4.293, P = 0.038). In conclusion, Allo-HSCT could be an effective consolidation therapy not just for patients with CR, but also for those who achieved PR. The prognosis is significantly improved by obtaining MRD negative prior to allogeneic transplantation.

Immunophenotypic but Not Genetic Changes Reclassify the Majority of Relapsed/Refractory Pediatric Cases of Early T-Cell Precursor Acute Lymphoblastic Leukemia

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) develops from very early cells with the potential for both T-cell and myeloid differentiation. The ambiguous nature of leukemic blasts in ETP-ALL may lead to immunophenotypic alterations at relapse. Here, we address immunophenotypic alterations and related classification issues, as well as genetic features of relapsed pediatric ETP-ALL. Between 2017 and 2022, 7518 patients were diagnosed with acute leukemia (AL). In addition to conventional immunophenotyping, karyotyping, and FISH studies, we performed next-generation sequencing of the T-cell receptor clonal repertoire and reverse transcription PCR and RNA sequencing for patients with ETP-ALL at both initial diagnosis and relapse. Among a total of 534 patients diagnosed with T-cell ALL (7.1%), 60 had ETP-ALL (11.2%). Ten patients with ETP-ALL experienced relapse or progression on therapy (16.7%), with a median time to event of 5 months (ranging from two weeks to 5 years). Most relapses were classified as AL of ambiguous lineage (n = 5) and acute myeloid leukemia (AML) (n = 4). Major genetic markers of leukemic cells remained unchanged at relapse. Of the patients with relapse, four had polyclonal leukemic populations and a relapse with AML or bilineal mixed-phenotype AL (MPAL). Three patients had clonal TRD rearrangements and relapse with AML, undifferentiated AL, or retention of the ETP-ALL phenotype. ETP-ALL relapse requires careful clinical and laboratory diagnosis. Treatment decisions should rely mainly on initial examination data, taking into account both immunophenotypic and molecular/genetic characteristics.

Decoding the genetic symphony: Profiling protein-coding and long noncoding RNA expression in T-acute lymphoblastic leukemia for clinical insights

T-acute lymphoblastic leukemia (T-ALL) is a heterogeneous malignancy characterized by the abnormal proliferation of immature T-cell precursors. Despite advances in immunophenotypic classification, understanding the molecular landscape and its impact on patient prognosis remains challenging. In this study, we conducted comprehensive RNA sequencing in a cohort of 35 patients with T-ALL to unravel the intricate transcriptomic profile. Subsequently, we validated the prognostic relevance of 23 targets, encompassing (i) protein-coding genes-BAALC, HHEX, MEF2C, FAT1, LYL1, LMO2, LYN, and TAL1; (ii) epigenetic modifiers-DOT1L, EP300, EML4, RAG1, EZH2, and KDM6A; and (iii) long noncoding RNAs (lncRNAs)-XIST, PCAT18, PCAT14, LINC00202, LINC00461, LINC00648, ST20, MEF2C-AS1, and MALAT1 in an independent cohort of 99 patients with T-ALL. Principal component analysis revealed distinct clusters aligning with immunophenotypic subtypes, providing insights into the molecular heterogeneity of T-ALL. The identified signature genes exhibited associations with clinicopathologic features. Survival analysis uncovered several independent predictors of patient outcomes. Higher expression of MEF2C, BAALC, HHEX, and LYL1 genes emerged as robust indicators of poor overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS). Higher LMO2 expression was correlated with adverse EFS and RFS outcomes. Intriguingly, increased expression of lncRNA ST20 coupled with RAG1 demonstrated a favorable prognostic impact on OS, EFS, and RFS. Conclusively, several hitherto unreported associations of gene expression patterns with clinicopathologic features and prognosis were identified, which may help understand T-ALL's molecular pathogenesis and provide prognostic markers.

Comparison of flowcytometry-based scoring system for the diagnosis of early T precursor-acute lymphoblastic leukemia

BACKGROUND

Early T cell precursor-acute lymphoblastic leukemia (ETP-ALL) is a hematolymphoid malignancy where the blasts demonstrate T cell differentiation markers along with stem cell and myeloid antigen expression. The differential diagnosis of ETP-ALL from non-ETP ALL and mixed phenotype acute leukemia is often challenging due to its overlapping immunophenotypic picture with co-expression of myeloid antigens. In this study, we endeavored to describe the immune-phenotype profile of ETP-ALL in our patients and compared the utility of four different scoring systems for better discrimination of these entities.

METHODS

This retrospective analysis included 31 ETP-ALL out of 860 acute leukemia cases consecutively diagnosed at the two tertiary care centers. Flowcytometry-based immunophenotype was reviewed for all the cases, and the utility of four flow-based objective scorings was assessed for the diagnosis of ETP-ALL. Receiver operating curves were drawn to compare the different flow-based scoring systems.

RESULTS

The prevalence of ETP-ALL was 40% (n = 31/77 T-ALL) in our study group, comprised mainly of adults with a median age of 20 years. The five-marker scoring system had the maximum area under the curve, followed by the seven-marker scoring system. A cut-off of ≥2.5 was more specific (sensitivity: 91%; specificity: 100%), while a score of ≥1.5 was more sensitive but slightly less specific (sensitivity: 94%, specificity: 96%).

CONCLUSION

The WHO criteria for the diagnosis of ETP-ALL should be followed across all laboratories to avoid confusion and for better treatment stratification. Flow-based scoring systems can be objectively employed for better detection of cases.

A Comparative Analysis of Early T-Cell Precursor Lymphoblastic Leukemia/Lymphoma (ETP-ALL/LBL) and Non-ETP-ALL/LBL in a Tertiary Cancer Care Center Based in Western India

Early T-cell precursor lymphoblastic leukemia (ETP-ALL) has a unique immunophenotype with very early T-cell differentiation. The current study summarises the distinct clinicopathological aspects of ETP-ALL and compares them with non-ETP-ALL. Twenty-nine ETP-ALL and 191 non-ETP-ALL cases were retrieved between 2018 and 2021. A P value was determined for each of the patient charaterisics (Table 1) to see for any significant relationship (P < 0.05) with ETP-ALL versus non-ETP-ALL. Kaplan-Meier log rank test was applied to look for any significant differences in OS for both the ALLs. ETP-ALL had an incidence of 12.6% out of total T-Acute lymphoblastic leukemia (T-ALL/LBL) in the past 3-years. Compared to non-ETP-ALL, ETP-ALL cases were associated with lower median age and male-to-female ratio. There was no statistically significant difference in the complete remission rate between both the subtypes. ETP-ALL was seen to be associated with high induction failure and relapse rate compared to non-ETP-ALL. To summarise, since the 2-year OS was poor compared to western research (for both ALLs), an intensive chemo-regimen should be implemented in the current situation. Some unusual markers were observed on flow-cytometry (ETP-ALL), which can be useful for MRD quantification, prognosis, and further trials for newer targeted therapies.

Immunophenotypic characterization of acute leukemias in Bahia, Brazil

OBJECTIVE

To characterize the immunophenotypic profile of acute leukemias in the population of the state of Bahia, Brazil.

METHODS

This is a descriptive, retrospective study. From 2014 to 2018, 796 new cases of acute leukemia were evaluated. The data were obtained from analysis of reports and records of tests performed by flow cytometry immunophenotyping. All individuals of all age groups diagnosed as acute lymphoblastic leukemia or acute myeloid leukemia were included in the study. Demographic variables and expression of leukemia antigens were evaluated.

RESULTS

Most cases were diagnosed as acute myeloid leukemia and 42.7% as acute lymphoblastic leukemia. Significant differences were found in expression of markers in acute leukemias when age groups were compared, as well as in demographic characteristics. B-cell acute lymphoblastic leukemia was more prevalent than cases of T-cell origin. Assessing the aberrant markers in acute myeloid leukemias, the non-acute promyelocytic leukemia group presented expression of CD7 and CD56 as the most frequent ones. In B-cell acute lymphoblastic leukemia, the most frequent aberrant markers were CD66c, CD13 and CD33.

CONCLUSION

Significant differences were found as to several antigens when comparing adults and children, and these findings may contribute to future studies correlating the phenotypic profile to genetic characteristics and therapeutic response, including specific antigen therapies, which may be better targeted.

Relevance of flow cytometry categorization and end-of-induction measurable residual disease assessment in pediatric and adult T-lymphoblastic leukemia patients

Background

T-lymphoblastic leukemia (T-ALL) patients expressing myeloid/stem cell antigens are classified as early T-cell precursor lymphoblastic leukemia (ETP-ALL) or near-ETP-ALL.

Methods

Clinico-laboratory profiles, flow cytometric end-of-induction measurable residual disease (EOI-MRD), and survival of treatment naïve T-ALL patients were analyzed according to their immunophenotypic subtypes.

Results

Among 81 consecutive T-ALL patients diagnosed, 21% (N=17) were ETP-ALL and 19% (N=15) were near-ETP-ALL. EOI-MRD was detectable in 39% of the 59 samples tested (31.6% of pediatric samples and 52.4% of adult samples). The frequency of EOI-MRD positivity was significantly higher among ETP-ALL (75%, P=0.001) and near-ETP-ALL (71%, P=0.009) patients compared to that in conventional-T-ALL (con-T-ALL) patients (22.5%). CD8 (P=0.046) and CD38 (P=0.046) expressions were significantly upregulated in the EOI blasts of con-T-ALL and ETP-ALL samples, respectively. The 2-year rates of overall (OS), relapse-free (RFS), and event-free survival (EFS) among the T-ALL patients (pediatric vs. adult) was 79.5% vs. 39.8% (P<0.001), 84.3% vs. 60.4% (P=0.026), and 80.3% vs. 38% (P<0.001), respectively. Univariate analysis revealed that 2-year EFS and RFS of pediatric T-ALL patients was independent of T-ALL subtype and was influenced only by EOI-MRD status. However, 2-year OS, RFS, and EFS among adult T-ALL patients were EOI-MRD independent and influenced only by the near-ETP-ALL phenotype.

Conclusion

Two-year survival among pediatric and adult T-ALL patients is attributed to EOI-MRD status and near-ETP-ALL phenotype, respectively.

In Silico Integration of Transcriptome and Interactome Predicts an ETP-ALL-Specific Transcriptional Footprint that Decodes its Developmental Propensity

Early T precursor acute lymphoblastic leukemia (ETP-ALL) exhibits poor clinical outcomes and high relapse rates following conventional chemotherapeutic protocols. Extensive developmental flexibility of the multipotent ETP-ALL blasts with considerable intra-population heterogeneity in terms of immunophenotype and prognostic parameters might be a target for novel therapeutic interventions. Using a public gene expression dataset (GSE28703) from NCBI GEO DataSets with 12 ETP-ALL and 40 non-ETP-ALL samples, such heterogeneity was found to be reflected in their transcriptome as well. Hub genes were identified from the STRING-derived functional interaction network of genes showing differential expression between ETP-ALL and non-ETP-ALL as well as variable expression across ETP-ALL. Nine genes (KIT, HGF, NT5E, PROM1, CD33, ANPEP, CDH2, IL1B, and CXCL2) among the hubs were further validated as possible diagnostic ETP-ALL markers using another gene expression dataset (GSE78132) with 17 ETP-ALL and 27 non-ETP-ALL samples. Linear dimensionality reduction analysis with the expression levels of the hub genes in ETP-ALL revealed their divergent inclinations towards different hematopoietic lineages, proposing them as novel indicators of lineage specification in the incompletely differentiated ETP-ALL blasts. This further led to the formulation of a personalized lineage score calculation algorithm, which uncovered a considerable B-lineage-bias in a substantial fraction of ETP-ALL subjects from the GSE28703 and GSE78132 cohorts. In addition, STRING-derived physical interactome of the potential biomarkers displayed complete segregation of the B-lineage-skewed markers from other lineage-associated factors, highlighting their distinct functionality and possible druggability in ETP-ALL. A panel of these biomarkers might be useful in pinpointing the dominant lineage specification programmes in the ETP-ALL blasts on a personalized level, urging the development of novel lineage-directed precision therapies as well as repurposing of existing therapies against leukemia of different hematopoietic lineages; which might overcome the drawbacks of conventional chemotherapy.

Inside the biology of early T-cell precursor acute lymphoblastic leukemia: the perfect trick

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a rare, distinct subtype of T-ALL characterized by genomic instability, a dismal prognosis and refractoriness to standard chemotherapy. Since its first description in 2009, the expanding knowledge of its intricate biology has led to the definition of a stem cell leukemia with a combined lymphoid-myeloid potential: the perfect trick. Several studies in the last decade aimed to better characterize this new disease, but it was recognized as a distinct entity only in 2016. We review current insights into the biology of ETP-ALL and discuss the pathogenesis, genomic features and their impact on the clinical course in the precision medicine era today.

Early T-Cell Precursor Acute Lymphoblastic Leukemia: Diagnosis, Updates in Molecular Pathogenesis, Management, and Novel Therapies

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinct subtype of T lymphoblastic leukemia (T-ALL) identified in 2009, due to its unique immunophenotypic and genomic profile. The outcome of patients was poor in earlier studies, and they were prone to have induction failure, with more frequent relapse/refractory disease. Recent advances had been made in discoveries of genetic aberrations and molecular pathogenesis of ETP-ALL. However, the diagnosis and management of ETP-ALL is still challenging. There are limited choices of novel therapies so far. In this review article, it highlighted the diagnostic issue of ETP-ALL, pitfall in diagnosis, and strategy of accurate diagnosis. The review also summarized current understanding of molecular mechanism of leukemogenesis. The emerging role of risk-adapted therapy and allogenic stem cell transplant in optimizing the outcome of patients with ETP-ALL was discussed. Finally, some potential novel therapies were proposed based on the current understanding of molecular pathogenesis.

Clinicopathological and immunophenotypic features of early T cell precursor acute lymphoblastic leukaemia: A flow cytometry score for the initial diagnosis

OBJECTIVE

To assess the prevalence of early T precursor-acute lymphoblastic leukaemia (ETP-ALL), study its clinicopathological features and devise a 'flow score' based on immunophenotypic profiles.

MATERIAL METHODS

This was a retrospective study where clinical and laboratory data of all consecutive T-ALL cases were analysed to identify features differentiating ETP from non-ETP-ALL. The utility of a flow score based on the five commonly used markers in leukaemia panels for T-ALL (CD34, CD8, CD5, CD13 and CD33) was evaluated to differentiate ETP from non-ETP-ALL.

RESULTS

Early T precursor-acute lymphoblastic leukaemia constituted 24.2% (n = 29) of all T-ALL cases. It was significantly more common in adults (30.2%) as compared to paediatric (17.5%) patients (P = .046). The median age of presentation was significantly higher than the non-ETP group. (24 vs 19 years; P = .01). Patients with ETP-ALL usually presented with organomegaly, lymphadenopathy, lower levels of haemoglobin, total leucocyte count, peripheral blood blast proportion and LDH levels as compared to non-ETP-ALL. The majority of ETP-ALL cases had L2 morphology with a moderate amount of cytoplasm showing frequent blebbing. A flow score cut-off value of ≥3 on ROC curve analysis had a sensitivity and specificity of 100% and 94.6% respectively.

CONCLUSION

Early T precursor-acute lymphoblastic leukaemia had unique clinical and laboratory features. The prevalence of this entity is more common in the adult population. A flow score based on a minimum of five widely used markers can confidently identify ETP-ALL and should be included in the primary panel of markers used for flow cytometric analysis.

Early precursor T-cell acute lymphoblastic leukemia: current paradigms and evolving concepts

Early precursor T cell-acute lymphoblastic leukemia (ETP-ALL) is a rare entity characterized by chemo-resistance and a paucity of data regarding optimal management. We review here the literature regarding the management of ETP-ALL and focus on the recent, emerging data, regarding the potential role of molecularly targeted approaches with a focus on venetoclax.

Photoluminescent Detection of Human T-Lymphoblastic Cells by ZnO Nanorods

The precise detection of cancer cells currently remains a global challenge. One-dimensional (1D) semiconductor nanostructures (e.g., ZnO nanorods) have attracted attention due to their potential use in cancer biosensors. In the current study, it was demonstrated that the possibility of a photoluminescent detection of human leukemic T-cells by using a zinc oxide nanorods (ZnO NRs) platform. Monoclonal antibodies (MABs) anti-CD5 against a cluster of differentiation (CD) proteins on the pathologic cell surface have been used as a bioselective layer on the ZnO surface. The optimal concentration of the protein anti-CD5 to form an effective bioselective layer on the ZnO NRs surface was selected. The novel biosensing platforms based on glass/ZnO NRs/anti-CD5 were tested towards the human T-lymphoblast cell line MOLT-4 derived from patients with acute lymphoblastic leukemia. The control tests towards MOLT-4 cells were performed by using the glass/ZnO NRs/anti-IgG2a system as a negative control. It was shown that the photoluminescence signal of the glass/ZnO NRs/anti-CD5 system increased after adsorption of T-lymphoblast MOLT-4 cells on the biosensor surface. The increase in the ZnO NRs photoluminescence intensity correlated with the number of CD5-positive MOLT-4 cells in the investigated population (controlled by using flow cytometry). Perspectives of the developed ZnO platforms as an efficient cancer cell biosensor were discussed.

Early T precursor acute lymphoblastic leukaemia/lymphoma shows differential immunophenotypic characteristics including frequent CD33 expression and in vitro response to targeted CD33 therapy

The differential immunophenotypic characteristics of early T precursor (ETP) acute lymphoblastic leukaemia/lymphoma (ALL) remain incompletely characterized. The study group (n = 142) included 106 (74·7%) men and 36 (25·3%) women with a median age of 34·9 years (range, 2-79) at diagnosis. Patients were subtyped by flow cytometry immunophenotyping as follows: 33 (23·2%) ETP; 32 (22·5%) early non-ETP; 60 (42·2%) thymic; and 17 (12·1%) mature. Excepting definitional markers, there was a significant differential expression of the markers CD2, CD10, CD33 and TdT between ETP-ALL and non-ETP-ALL. Positive CD33 expression (≥20% of leukaemic blasts) was detected in 21/33 (63%) ETP-ALL compared with 17/95 (17·9%) non-ETP-ALL (P < 0·001). Notably, targeted anti-CD33 therapy with IMGN779 resulted in significant growth inhibition and increased apoptosis in ETP-ALL cells in vitro. An 11-marker T-ALL immunophenotype score discriminated reliably between ETP and non-ETP ALL. Longitudinal analysis of ETP-ALL cases in this study demonstrated that the immunophenotype may be occasionally dynamic but is largely stable over the disease course. In summary, identification of ETP-ALL might be enhanced by using an 11-marker T-ALL immunophenotype score. CD33 expression is frequent in ETP-ALL, and in vitro data suggest that exploring anti-CD33 therapy in ETP-ALL is warranted.

Bacterial translocation in acute lymphocytic leukemia

Bloodstream infection (BSI) is the major cause of mortality in acute lymphocytic leukemia (ALL). Causative pathogens in BSI originate from the gut microbiota due to an increase in intestinal permeability, a process known as bacterial translocation (BT). The gut microbiota in physiological conditions is controlled by a large number of immune cells as part of the gut-associated lymphoid tissue (GALT).The aim of the current study was to investigate the mechanism of bacterial translocation in leukemia by identifying and characterizing alterations in the GALT in leukemic mouse model. Our studies revealed a severe impairment of the GALT characterized by a loss of lymphatic cells in ALL, which eventually led to BSI. We identified differentially expressed genes in the intraepithelium and the lamina propria, which may contribute to BT and to the impairment of lymphocyte migration.

CDKN2B downregulation and other genetic characteristics in T-acute lymphoblastic leukemia

We identified principal genetic alterations in 97.1% (99/102) of patients with T-acute lymphoblastic leukemia (T-ALL) using integrative genetic analyses, including massive parallel sequencing and multiplex ligation-dependent probe amplification (MLPA). A total of 133 mutations were identified in the following genes in descending order: NOTCH1 (66.7%), FBXW7 (19.6%), PHF6 (15.7%), RUNX1 (12.7%), NRAS (10.8%), and DNMT3A (9.8%). Copy number alterations were most frequently detected in CDKN2B, CDKN2A, and genes on 9p21.3 in T-ALL (45.1%). Gene expression data demonstrated the downregulation of CDKN2B in most cases of T-ALL, whereas CDKN2A downregulation was mainly restricted to deletions. Additional quantitative methylation analysis demonstrated that CDKN2B downregulation stemmed from deletion and hypermethylation. Analysis of 64 patients with CDKN2B hypermethylation indicated an association with an older age of onset and early T cell precursor ALL, which involved very early arrest of T cell differentiation. Genes associated with methylation and myeloid neoplasms, including DNMT3A and NRAS, were more commonly mutated in T-ALL with CDKN2B hypermethylation. In particular, a CDKN2B biallelic deletion or high methylation level (≥45%), the age of onset, and the GATA3 and SH2B3 mutations were factors associated with a poor prognosis. This study clarifies that one of the most important genetic events in T-ALL, namely, CDKN2B downregulation, occurs mechanistically via deletion and hypermethylation. Different susceptible genetic backgrounds exist based on the CDKN2B downregulation mechanism.

Immunophenotypic analysis of adult patients with T-cell lymphoblastic lymphoma treated with hyper-CVAD

OBJECTIVES

Immunophenotype is an important prognostic factor for childhood and adult T-cell acute lymphoblastic leukemia. However, immunophenotypic data from adult patients with T-cell lymphoblastic lymphoma (T-LBL) are scarcely available.

METHODS

Subjects were unselected adult patients with T-LBL who were treated with intensive chemotherapy. Immunophenotyping of tumor cells was performed according to standard techniques.

RESULTS

A total of eight patients with a median age of 31 years were analyzed who received hyper-CVAD treatment for LBL. Immunophenotypic analysis showed that the most common tumor type was cortical T-cell type [early T (n = 2), cortical T (n = 4), and medullary T (n = 2)]. Two patients diagnosed with early T-cell type had early disease progression.

CONCLUSIONS

Assessment of T-cell differentiation stages in malignant T lymphoblasts would be important in choosing treatment strategies for adult patients with T-LBL.

DNA Methylation Adds Prognostic Value to Minimal Residual Disease Status in Pediatric T-Cell Acute Lymphoblastic Leukemia

BACKGROUND

Despite increased knowledge about genetic aberrations in pediatric T-cell acute lymphoblastic leukemia (T-ALL), no clinically feasible treatment-stratifying marker exists at diagnosis. Instead patients are enrolled in intensive induction therapies with substantial side effects. In modern protocols, therapy response is monitored by minimal residual disease (MRD) analysis and used for postinduction risk group stratification. DNA methylation profiling is a candidate for subtype discrimination at diagnosis and we investigated its role as a prognostic marker in pediatric T-ALL.

PROCEDURE

Sixty-five diagnostic T-ALL samples from Nordic pediatric patients treated according to the Nordic Society of Pediatric Hematology and Oncology ALL 2008 (NOPHO ALL 2008) protocol were analyzed by HumMeth450K genome wide DNA methylation arrays. Methylation status was analyzed in relation to clinical data and early T-cell precursor (ETP) phenotype.

RESULTS

Two distinct CpG island methylator phenotype (CIMP) groups were identified. Patients with a CIMP-negative profile had an inferior response to treatment compared to CIMP-positive patients (3-year cumulative incidence of relapse (CIR3y ) rate: 29% vs. 6%, P = 0.01). Most importantly, CIMP classification at diagnosis allowed subgrouping of high-risk T-ALL patients (MRD ≥0.1% at day 29) into two groups with significant differences in outcome (CIR3y rates: CIMP negative 50% vs. CIMP positive 12%; P = 0.02). These groups did not differ regarding ETP phenotype, but the CIMP-negative group was younger (P = 0.02) and had higher white blood cell count at diagnosis (P = 0.004) compared with the CIMP-positive group.

CONCLUSIONS

CIMP classification at diagnosis in combination with MRD during induction therapy is a strong candidate for further risk classification and could confer important information in treatment decision making.

How I treat T-cell acute lymphoblastic leukemia in adults

T-cell immunophenotype of acute lymphoblastic leukemia (T-ALL) is an uncommon aggressive leukemia that can present with leukemic and/or lymphomatous manifestations. Molecular studies are enhancing our understanding of the pathogenesis of T-ALL, and the discovery of activating mutations of NOTCH1 and FBXW7 in a majority of patients has been a seminal observation. The use of pediatric intensive combination chemotherapy regimens in adolescents and young adults has significantly improved the outcome of patients with T-ALL. The use of nelarabine for relapsed and refractory T-ALL results in responses in a substantial minority of patients. Allogeneic hematopoietic cell transplantation (HCT) still plays a key role in patients with high-risk or relapsed/refractory disease. γ-Secretase inhibitors hold promise for the treatment of patients with NOTCH1 mutations, and the results of clinical trials with these agents are eagerly awaited. It is recommended that younger patients receive a pediatric-intensive regimen. Older and unfit patients can receive suitable multiagent chemotherapy and be allocated to HCT based on their response, risk factors, and comorbidities. Although advances in the treatment of T-ALL have lagged behind those of B-cell ALL, it is hoped that the molecular revolution will enhance our understanding of the pathogenesis and treatment of this aggressive lymphoid malignancy.