T-cell Acute Lymphoblastic Leukemia Research Articles

The Clinical and Molecular Characterization of Distinct Subtypes in Adult T Cell Acute Lymphoblastic Leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is a clonal proliferative malignant disease characterized by abnormal T-cell development. The classification of T-ALL primarily hinges on immunophenotype, encompassing early T-cell precursor (ETP)-ALL, near-ETP-ALL, and non-ETP-ALL. We summarized clinical information from 117 patients, with genetic data available for 77 patients and transcriptomic data available for 24 patients. An ETP-like score model was established based on transcriptome, aiming to address the subjectivity in the current T-ALL immunophenotype classification. The retrospective analysis indicated that ETP immunophenotype was not a prognostic factor for T-ALL patients. Compared to non-ETP-ALL patients, ETP-like patients including ETP-ALL and near-ETP-ALL were more likely to carry MED12 gene mutations, which may predict a dismal outcome. Transcriptomic analysis suggested that T-ALL patients with different immunophenotypes were in accordance with the T-cell development trajectory, while ETP-like patients exhibited characteristics of early T-cell development. Finally, we established an ETP-like score model and confirmed its efficiency across four independentcohorts, with sensitivity exceeding 80%. And T-ALL patients with high ETP-like score were associated with poor prognosis. In conclusion, our study elucidated the clinical and molecular features of distinct subtypes of T-ALL patients, providing new valuable insights for T-ALL classification.

The mitochondria as an emerging target of self-renewal in T-cell acute lymphoblastic leukemia

ABSTRACT Acute lymphocytic leukemia (ALL) is the most common leukemia in children, with the T-cell subtype (T-ALL) accounting for 15% of those cases. Despite advancements in the treatment of T-ALL, patients still face a dismal prognosis following their first relapse. Relapse can be attributed to the inability of chemotherapy agents to eradicate leukemia stem cells (LSC), which possess self-renewal capabilities and are responsible for the long-term maintenance of the disease. Mitochondria have been recognized as a therapeutic vulnerability for cancer stem cells, including LSCs. Mitocans have shown promise in T-ALL both in vitro and in vivo, with some currently in early-phase clinical trials. However, due to challenges in studying LSCs in T-ALL, our understanding of how mitochondrial function influences self-renewal remains limited. This review highlights the emerging literature on targeting mitochondria in diverse T-ALL models, emphasizing specific mitochondrial vulnerabilities linked to LSC self-renewal and their potential to significantly improve T-ALL treatment.

ID3 promotes erythroid differentiation and is repressed by a TAL1-PRMT6 complex.

Erythropoiesis is controlled by transcription factors that recruit epigenetic cofactors to establish and maintain erythrocyte-specific gene expression patterns while repressing alternative lineage commitment. The transcription factor TAL1 (T-cell acute lymphocytic leukemia 1) is critical for establishing erythroid gene expression. It acts as an activator or repressor of genes, depending on associated epigenetic cofactors. Understanding the epigenetic function of TAL1 during erythropoiesis is key to improving invitro erythroid differentiation and understanding pathological erythropoiesis. Therefore, the regulatory mechanisms that control the function of TAL1 during erythropoiesis are under intense investigation. Here, we show that TAL1 interacts with protein-arginine-methyltransferase-6 (PRMT6) on the ID3 (inhibitor-of-DNA-binding-3) gene in K562 and hCD34+ cells. The ID protein family is a critical transcriptional regulator of hematopoietic cell differentiation. We show that TAL1 and PRMT6 are present at the ID3 promoter, and that TAL1 is involved in the recruitment of PRMT6. Here, PRMT6 epigenetically regulates ID3 expression by mediating dimethylation of histone 3 at arginine 2. Thus, TAL1-PRMT6 epigenetically represses ID3 expression in progenitors, which is relieved upon erythroid differentiation, leading to increased expression. Overexpression of ID3 in primary hCD34+ cells enhances erythropoiesis. Our results show that a TAL1-PRMT6 complex regulates genes important for erythropoiesis, such as ID3. Manipulation of ID3 expression may be a way to promote invitro differentiation of hCD34+ cells into erythrocytes.

274 Absorption of oral chemotherapy in a pediatric patient with T-cell acute lymphoblastic leukemia, short bowel syndrome, and Skewed 6-mercaptopurine metabolism

274 Absorption of oral chemotherapy in a pediatric patient with T-cell acute lymphoblastic leukemia, short bowel syndrome, and Skewed 6-mercaptopurine metabolism

Branching NOTCH1 to DNA damage in T-cell acute lymphoblastic leukemia.

Not available.

T-cell acute lymphoblastic leukemia with involvement of extramedullary sites, including the pericardium.

T-cell acute lymphoblastic leukemia with involvement of extramedullary sites, including the pericardium.

Homoharringtonine in Relapsed/Refractory Paediatric T-Cell Acute Lymphoblastic Leukaemia-A Case Series and a Report on the Use of In Vitro Drug Profiling.

Paediatric relapse/refractory T-cell acute lymphoblastic leukaemia (T-ALL) is notoriously difficult to treat. This group of heavily pre-treated patients needs effective agents that can rapidly control the disease while not having significant toxicity. Homoharringtonine (HHT) has been widely used in children with acute myeloid leukaemia, but there is little information on T-ALL. In this case series, HHT, in combination with other agents, achieved good response in five paediatric patients with T-ALL. The in vitro drug profiling in one patient demonstrated clinical correlation with HHT activity. The study sheds light on the potential of precision medicine for patients with relapsed/refractory leukaemia.

Targeting the IKZF1/BCL-2 axis as a novel therapeutic strategy for treating acute T-cell lymphoblastic leukemia

ABSTRACT Objectives Acute T-cell lymphoblastic leukemia (T-ALL) is a severe hematologic malignancy with limited treatment options and poor long-term survival. This study explores the role of IKZF1 in regulating BCL-2 expression in T-ALL. Methods CUT&Tag and CUT&Run assays were employed to assess IKZF1 binding to the BCL-2 promoter. IKZF1 overexpression and knockdown experiments were performed in T-ALL cell lines. The effects of CX-4945 and venetoclax, alone and in combination, were evaluated in vitro and in vivo T-ALL models. Results CUT&Tag sequencing identified IKZF1 binding to the BCL-2 promoter, establishing it as a transcriptional repressor. Functional assays demonstrated that IKZF1 overexpression reduced BCL-2 mRNA levels and increased repressive histone marks at the BCL-2 promoter, while IKZF1 knockdown led to elevated BCL-2 expression. CX-4945, a CK2 inhibitor, could reduced BCL-2 levels in T-ALL cells. Notably, knockdown of IKZF1 partially rescued the CX-4945-induced repression of BCL-2. These results underscore the CK2-IKZF1 signaling axis as a key regulator of BCL-2 expression. In vitro, CX-4945 enhanced the cytotoxicity of venetoclax, with the combination showing significant synergistic effects and increased apoptosis in T-ALL cell lines. In vivo studies with cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) models demonstrated that CX-4945 and venetoclax combined therapy provided superior therapeutic efficacy, reducing tumor burden and prolonging survival compared to single-agent treatments. Conclusions IKZF1 represses BCL-2 in T-ALL, and targeting the CK2-IKZF1 axis with CX-4945 and venetoclax offers a promising therapeutic strategy, showing enhanced efficacy and potential as a novel treatment approach for T-ALL.

LLT1 overexpression renders allogeneic-NK resistance and facilitates the generation of enhanced universal CAR-T cells

BackgroundThe benefit of universal CAR-T cells over autologous CAR-T cell therapy is that they are a treatment that is ready to use. However, the prevention of graft-versus-host disease (GVHD) and host-versus-graft reaction (HVGR) remains challenging. Deleting class I of human leukocyte antigen (HLA-I) and class II of human leukocyte antigen (HLA-II) can prevent rejection by allogeneic T cells; however, natural killer (NK) cell rejection due to the loss of self-recognition remains unresolved. This study tested whether the overexpression of Lectin-like transcript 1 (LLT1), an NK cell inhibitory ligand, in T cell receptor (TCR) and HLA-I/II disrupted universal CD38-targeting CAR-T cells could prevent rejection by allogeneic NK cells.MethodsWe generated CD38-targeting universal CAR-T cells by transducing T cells with lentiviruses encoding the CD38 CAR and LLT1 constructs. T cells were subjected to CD38, TCR, HLA-I, and HLA-II gene knockdown using CRISPR/Cas9, followed by lentiviral transduction. We performed cytotoxicity, proliferation, and cytokine assays to evaluate the functionality of universal chimeric antigen receptor-T cell (UCAR-T) cells and conducted in vitro and in vivo assays, including allogeneic responses and RNA sequencing, to assess their resistance to allogeneic T and NK cells, anti-leukemia efficacy, and persistence in treating hematologic malignancies.ResultsGenetic editing of CD38 universal CAR-T cells, including CD38, T cell receptor alpha constant (TRAC), beta-2-microglobulin (B2M), and class II major histocompatibility complex transactivator (CIITA) knockdowns, was successfully achieved. In vitro, LLT1 overexpression boosted CAR-T cell proliferation and antitumor activity, leading to a transcriptional signature characterized by elevated stemness-related markers (SELL, BCL6, TCF7, and CD27) and increased levels of IL-10 and other cytokines. It also effectively mitigates rejection by allogeneic NK and T cells. In a humanized T-cell acute lymphoblastic leukemia (T-ALL) model, CD38 allogeneic universal CAR-T cells demonstrated superior survival rates and tumor clearance with reduced inflammatory responses.ConclusionAccording to these results, LLT1 overexpression enhances UCAR-T cell activity and prevents allogeneic rejection, providing essential insights for the development of universal CAR-T cell therapy.

β-Catenin Regulates Glycolytic and Mitochondrial Function in T-Cell Acute Lymphoblastic Leukemia

Background: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy characterized by a poor prognosis. β-catenin is implicated in the progression of T-ALL, yet the precise mechanisms of β-catenin involvement in the pathogenesis of T-ALL, particularly concerning metabolic processes, remain inadequately elucidated. Methods: A β-catenin knockout cell line was generated in the human leukemic cell line Jurkat using the CRISPR-Cas9 technique. Subsequently, assays were performed to evaluate cell proliferation, apoptosis, and metabolic activity. Comparative transcriptomic analysis was conducted between control cells and β-catenin knockout cells. Finally, a mouse xenograft model was employed to assess whether β-catenin knockout attenuates tumor growth and infiltration in vivo. Results: The deletion of β-catenin significantly inhibited proliferation and induced apoptosis. Additionally, the silencing of β-catenin led to the inhibition of glycolysis and a reduction in both mitochondrial mass and membrane potential. These results indicate that β-catenin may play a crucial role in regulating cell proliferation and apoptosis through the modulation of glycolytic activity and mitochondrial function in T-ALL. Conclusions: In summary, our findings uncover a novel mechanism by which β-catenin influences glycolysis and mitochondrial function in the progression of T-ALL, thereby identifying a potential therapeutic target for patients with relapsed T-ALL.

Targeting LMO2-induced autocrine FLT3 signaling to overcome chemoresistance in early T-cell precursor acute lymphoblastic leukemia.

Early T-cell Precursor Acute Lymphoblastic Leukemia (ETP-ALL) is an immature subtype of T-cell acute lymphoblastic leukemia (T-ALL) commonly show deregulation of the LMO2-LYL1 stem cell transcription factors, activating mutations of cytokine receptor signaling, and poor early response to intensive chemotherapy. Previously, studies of the Lmo2 transgenic mouse model of ETP-ALL identified a population of stem-like T-cell progenitors with long-term self-renewal capacity and intrinsic chemotherapy resistance linked to cellular quiescence. Here, analyses of Lmo2 transgenic mice, patient-derived xenografts, and single-cell RNA-sequencing data from primary ETP-ALL identified a rare subpopulation of leukemic stem cells expressing high levels of the cytokine receptor FLT3. Despite a highly proliferative state, these FLT3-overexpressing cells had long-term self-renewal capacity and almost complete resistance to chemotherapy. Chromatin immunoprecipitation and assay for transposase-accessible chromatin sequencing demonstrated FLT3 and its ligand may be direct targets of the LMO2 stem-cell complex. Media conditioned by Lmo2 transgenic thymocytes revealed an autocrine FLT3-dependent signaling loop that could be targeted by the FLT3 inhibitor gilteritinib. Consequently, gilteritinib impaired in vivo growth of ETP-ALL and improved the sensitivity to chemotherapy. Furthermore, gilteritinib enhanced response to the BCL2 inhibitor venetoclax, which may enable "chemo-free" treatment of ETP-ALL. Together, these data provide a cellular and molecular explanation for enhanced cytokine signaling in LMO2-driven ETP-ALL beyond activating mutations and a rationale for clinical trials of FLT3 inhibitors in ETP-ALL.

CpG island methylator phenotype classification improves risk assessment in pediatric T-cell Acute Lymphoblastic Leukemia.

Current intensive treatment of pediatric T-cell acute lymphoblastic leukemia (T-ALL) has substantial side-effects, highlighting a need for novel biomarkers to improve risk stratification. Canonical biomarkers such as genetics and immunophenotype are largely not used in pediatric T-ALL stratification. This study aimed to validate the prognostic relevance of DNA methylation CpG island methylator phenotype (CIMP) risk stratification in two pediatric T-ALL patient cohorts: the Nordic NOPHO ALL2008 T-ALL study cohort (n=192) and the Dutch DCOG ALL-10/ALL-11 validation cohorts (n=156). Both cohorts showed that combining CIMP classification at diagnosis with measurable residual disease (MRD) at treatment day 29 or 33 significantly improved outcome prediction. The poor prognosis subgroup, characterized by CIMP low/D29 or D33 MRD≥0.1%, showed a cumulative incidence of relapse (pCIR5yr) of 29.0% and 23%, and overall survival (pOS5yr) of 59.7% and 65.4%, in NOPHO and DCOG, respectively. Conversely, a good prognosis subgroup was also identified representing CIMP high/D29 or D33 MRD<0.1% with pCIR5yr of 0% and 3.4%, and pOS5yr of 98.2% and 94.8%, in NOPHO and DCOG, respectively. For NOPHO, MRD was also evaluated on D15, and the relapse prediction accuracy of CIMP/D29 MRD (0.79) and CIMP/D15 MRD (0.75) classification was comparable, indicating potential for earlier stratification. The evaluation of the biology behind the CIMP subgroups revealed associations with transcriptome profiles, genomic aberrations, and mitotic history, suggesting distinct routes for leukemia development. In conclusion, integrating MRD assessment with the novel CIMP biomarker has the potential to improve risk stratification in pediatric T-ALL and guide future therapeutic decisions.

TLE4 is a repressor of the oncogenic activity of TLX3 in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disease originating from the malignant transformation of T-cell progenitors, caused by the accumulation of genetic aberrations. One-fifth of T-ALL patients are characterized by ectopic expression of the homeobox transcription factor TLX3. However, the role of TLX3 in T-ALL remains elusive, partly due to the lack of suitable study models. Strikingly, this TLX3-positive subgroup has a high frequency of FLT3 mutations, predominantly FLT3-ITD, in pediatric cases. To investigate this, we generated ex vivo cultured pro-T cells driven by the co-expression of TLX3 and FLT3-ITD, which conferred IL7 independent growth. This model allowed us to confirm that TLX3 expression and FLT3 signaling cooperate to transform T-cells and induce an oncogenic context. Data from this cell model, combined with gene expression data from TLX3 positive T-ALL cases, revealed a strong downregulation of the transcriptional repressor TLE4. Furthermore, TLE4 showed to have a repressive effect on ex vivo TLX3 T-ALL cell growth, likely caused by a partial reversal of the TLX3 transcriptional profile. In conclusion, we developed a TLX3+FLT3-ITD pro-T cell model and used it to illustrate that TLX3 directly represses TLE4 expression, which is beneficial for the oncogenic function of TLX3.

The efficacy and safety of nelarabine in relapsed or refractory T-cell acute lymphoblastic leukemia: a systematic review and meta-analysis.

T-cell Acute Lymphoblastic Leukemia (T-ALL) is a subtype of acute lymphoblastic leukemia characterized by the proliferation of abnormal T-cell precursors. Nelarabine, a purine analog, has been approved as a targeted therapy for patients with refractory or relapsed T-ALL. This study aims to evaluate the efficacy and safety of Nelarabine, either as monotherapy or in combination with other therapies, in treating T-ALL. A systematic review and meta-analysis were conducted following PRISMA guidelines. We searched Cochrane CENTRAL, PubMed, and Google Scholar up to August 2024 for studies evaluating Nelarabine's efficacy and safety in T-ALL patients. The primary outcome was complete response (CR), with secondary outcomes focusing on adverse events (AEs). Data were analyzed using a random effects model, with statistical significance set at p ≤ 0.05. Sixteen studies involving 1,865 patients were included, with 1,345 receiving Nelarabine. The pooled analysis revealed a CR rate of 37.9% (95% CI: 20.5-55.4%, p < 0.001) for Nelarabine monotherapy. Significant adverse events included neutropenia at 29.1% (95% CI: 9.1-49.1%, p < 0.001), thrombocytopenia at 32.4% (95% CI: 14.8-50.0%, p < 0.001), peripheral motor neuropathy at 17.1% (95% CI: 4.2-30.1%, p = 0.001), and peripheral sensory neuropathy at 15.3% (95% CI: 5.8-24.9%, p = 0.003). For combination therapy, infections occurred in 65.0% (95% CI: 27.1-103.0%, p < 0.001) of patients, febrile neutropenia in 48.7% (95% CI: -8.8-106.3%, p < 0.001), peripheral motor neuropathy in 10.5% (95% CI: 7.9-13.0%, p < 0.001), and peripheral sensory neuropathy in 23.1% (95% CI: 10.6-35.7%, p < 0.001). Nelarabine shows significant efficacy in treating refractory or relapsed T-ALL, with notable CR rates. However, its use, both as monotherapy and in combination therapy, is associated with considerable adverse events, particularly neurotoxicity and hematologic toxicities, necessitating careful monitoring. Further research is needed to optimize its application across diverse patient populations and to better manage its associated toxicities.

Relapsed childhood T-cell acute lymphoblastic leukemia and lymphoblastic lymphoma.

While outcomes for pediatric acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) have improved dramatically in recent decades, relapsed and refractory disease remain a significant therapeutic challenge. This is particularly true for patients with T-cell ALL and LBL, where survival for patients with relapsed/refractory disease remains dismal. Recent efforts to comprehensively profile the genomics of T-ALL/LBL to improve understanding of disease biology have enhanced our ability to identify high-risk patients at diagnosis who are more likely to relapse and have also identified novel targets for precision medicines. Novel immunotherapies have transformed the treatment landscape for patients with B-cell ALL (B-ALL). Many immunotherapies are under investigation in clinical trials for patients with T-ALL/LBL and early results are very promising. Given these insights into disease biology and the development of targeted and immune-based treatments, it is reasonable to hope for improved patient outcomes, although challenges still exist. In this review, we summarize the present state of understanding of the risk factors for relapse of T-ALL/LBL, established treatment regimens, and the promising small molecule inhibitors and immunotherapies with the potential to revolutionize the treatment of relapsed/refractory T-ALL/LBL.

Next generation thiazolyl ketone inhibitors of cytosolic phospholipase A2 α for targeted cancer therapy

Eicosanoids are key players in inflammatory diseases and cancer. Targeting their production by inhibiting Group IVA cytosolic phospholipase A2 (cPLA2α) offers a promising approach for cancer therapy. In this study, we synthesize a second generation of thiazolyl ketone inhibitors of cPLA2α starting with compound GK470 (AVX235) and test their in vitro and cellular activities. We identify a more potent and selective lead molecule, GK420 (AVX420), which we test in parallel with AVX235 and a structurally unrelated compound, AVX002 for inhibition of cell viability across a panel of cancer cell lines. From this, we show that activity of polycomb group repressive complex 2 is a key molecular determinant of sensitivity to cPLA2α inhibition, while resistance depends on antioxidant response pathways. Consistent with these results, we show that elevated intracellular reactive oxygen species and activating transcription factor 4 target gene expression precede cell death in AVX420-sensitive T-cell acute lymphoblastic leukemia cells. Our findings imply cPLA2α may support cancer by mitigating oxidative stress and inhibiting tumor suppressor expression and suggest that AVX420 has potential for treating acute leukemias and other cancers that are susceptible to oxidative cell death.

A distinct alternative mRNA splicing profile identifies the oncogenic CD44 transcript variant 3 in KMT2A-rearranged pediatric T-cell acute lymphoblastic leukemia cells.

T-cell acute lymphoblastic leukemia (T-ALL), which constitutes of 10-15% of all pediatric acute lymphoblastic leukemia (ALL) cases, is known for its complex pathology due to pervasive genetic and chromosomal abnormalities. Although most children are successfully cured, chromosomal rearrangements involving the KMT2A gene is considered a poor prognostic factor. In a cohort of 171 pediatric T-ALL samples, we have studied differences in gene and splice variant patterns in KMT2A-rearranged (KMT2A-r) T-ALL compared with KMT2A-negative (KMT2A-wt) T-ALL samples. Our results have identified a distinct gene expression and splice variant expression pattern in pediatric KMT2A-r patient samples including significant expression of splicing regulatory markers ESRP1 and MBNL3. Additionally, the prosurvival long transcript variant of BCL2 were upregulated in KMT2A-r compared with KMT2A-wt T-ALL samples. Lastly, increased levels of activating methylation in the promoter region of CD44 were identified followed by an upregulation of the oncogenic transcript variant CD44v3 in KMT2A-r T-ALL. Together, this suggests that CD44v3 could play a potential role as gene expression-based risk stratification of KMT2A-r T-ALL and could possibly serve as a therapeutic target using splicing modulators.

Super-Enhancer-Driven IRF2BP2 is Activated by Master Transcription Factors and Sustains T-ALL Cell Growth and Survival.

Super enhancers (SEs) are large clusters of transcriptional enhancers driving the expression of genes crucial for defining cell identity. In cancer, tumor-specific SEs activate key oncogenes, leading to tumorigenesis. Identifying SE-driven oncogenes in tumors and understanding their functional mechanisms is of significant importance. In this study, a previously unreported SE region is identified in T-cell acute lymphoblastic leukemia (T-ALL) patient samples and cell lines. This SE activates the expression of interferon regulatory factor 2 binding protein 2 (IRF2BP2) and is regulated by T-ALL master transcription factors (TFs) such as ETS transcription factor ERG (ERG), E74 like ETS transcription factor 1 (ELF1), and ETS proto-oncogene 1, transcription factor (ETS1). Hematopoietic system-specific IRF2BP2 conditional knockout mice is generated and showed that IRF2BP2 has minimal impact on normal T cell development. However, in vitro and in vivo experiments demonstrated that IRF2BP2 is crucial for T-ALL cell growth and survival. Loss of IRF2BP2 affects the MYC and E2F pathways in T-ALL cells. Cleavage under targets and tagmentation (CUT&Tag) assays and immunoprecipitation revealed that IRF2BP2 cooperates with the master TFs of T-ALL cells, targeting the enhancer of the T-ALL susceptibility gene recombination activating 1 (RAG1) and modulating its expression. These findings provide new insights into the regulatory network within T-ALL cells, identifying potential new targets for therapeutic intervention.

Contribution of copy number to improve risk stratification of adult T-cell acute lymphoblastic leukemia patients enrolled in measurable residual disease-oriented trials.

Not available.

HOPX as a tumour-suppressive protein in T-cell acute lymphoblastic leukaemia.

The homeodomain protein homeobox (HOPX), a multifaceted regulator of cellular functions and developmental processes, is predominantly expressed in stem cells across diverse tissues; it has also emerged as a tumour suppressor in various solid cancers. However, its role in haematological malignancies still remains undefined. This study aimed to elucidate its significance in T-cell acute lymphoblastic leukaemia (T-ALL). We firstly uncovered a novel link between reduced HOPX expression, its promoter hypermethylation and increased tumour burden in patients with T-ALL, suggesting its tumour-suppressive role. Next, we induced T-ALL by transducing intracellular NOTCH1 (ICN1) into mice with either conditional knock-in at the Rosa26 locus or knockout of Hopx. We found that T-ALL development was markedly accelerated and impeded in backgrounds with low and high Hopx expression respectively. Further analysis revealed Hopx's roles in modulating the Wnt-β-catenin pathway, a pivotal regulator of the downstream Myc signalling involved in T-ALL transformation and progression.