T-cell Acute Lymphoblastic Leukemia Cell Research Articles

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.

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.

Single-Cell Multiomics Reveals TCR Clonotype-Specific Phenotype and Stemness Heterogeneity of T-ALL Cells.

T-cell acute lymphoblastic leukaemia (T-ALL) is a heterogeneous malignant disease with high relapse and mortality rates. To characterise the multiomics features of T-ALL, we conducted integrative analyses using single-cell RNA, TCR and chromatin accessibility sequencing on pre- and post-treatment peripheral blood and bone marrow samples of the same patients. We found that there is transcriptional rewiring of gene regulatory networks in T-ALL cells. Some transcription factors, such as TCF3 and KLF3, showed differences in activity and expression levels between T-ALL and normal T cells and were associated with the prognosis of T-ALL patients. Furthermore, we identified multiple malignant TCR clonotypes among the T-ALL cells, where the clonotypes consisted of distinct combinations of the same TCR α and β chain per patient. The T-ALL cells displayed clonotype-specific immature thymocyte cellular characteristics and response to chemotherapy. Remarkably, T-ALL cells with an orphan TCRβ chain displayed the strongest stemness and resistance to chemotherapy. Our study provided transcriptome and epigenome characterisation of T-ALL cells categorised by TCR clonotypes, which may be helpful for the development of novel predictive markers to evaluate treatment effectiveness for T-ALL.

High CD44 expression and enhanced E-selectin binding identified as biomarkers of chemoresistant leukemic cells in human T-ALL.

T-cell acute lymphoblastic leukemia (T-ALL) is a hematopoietic malignancy characterized by increased proliferation and incomplete maturation of T-cell progenitors, for which relapse is often of poor prognosis. To improve patient outcomes, it is critical to understand the chemoresistance mechanisms arising from cell plasticity induced by the bone marrow (BM) microenvironment. Single-cell RNA sequencing of human T-ALL cells from adipocyte-rich and adipocyte-poor BM revealed a distinct leukemic cell population defined by quiescence and high CD44 expression (Ki67neg/lowCD44high). During in vivo treatment, these cells evaded chemotherapy, and were further called Chemotherapy-resistant Leukemic Cells (CLCs). Patient sample analysis revealed Ki67neg/lowCD44high CLCs at diagnosis and during relapse, with each displaying a specific transcriptomic signature. Interestingly, CD44high expression in T-ALL Ki67neg/low CLCs was associated with E-selectin binding. Analysis of 39 human T-ALL samples revealed significantly enhanced E-selectin binding activity in relapse/refractory samples compared with drug-sensitive samples. These characteristics of chemoresistant T-ALL CLCs provide key insights for prognostic stratification and novel therapeutic options.

ATP citrate lyase is an essential player in the metabolic rewiring induced by PTEN loss during T-ALL development.

Alterations inactivating the tumor suppressor gene PTEN drive the development of solid and hematological cancers, such as T-cell acute lymphoblastic leukemia (T-ALL), whereby PTEN loss defines poor-prognosis patients. We investigated the metabolic rewiring induced by PTEN loss in T-ALL, aiming at identifying novel metabolic vulnerabilities. We showed that the enzyme ATP citrate lyase (ACLY) is strictly required for the transformation of thymic immature progenitors and for the growth of human T-ALL, which remain dependent on ACLY activity even upon transformation. Whereas PTEN mutant mice all died within 17 weeks, the concomitant ACLY deletion prevented disease initiation in 70% of the animals. In these animals, ACLY promoted BCL-2 epigenetic upregulation and prevented the apoptosis of pre-malignant DP thymocytes. Transcriptomic and metabolic analysis of primary T-ALL cells next translated our findings to the human pathology, showing that PTEN-altered T-ALL cells activate ACLY and are sensitive to its genetic targeting. ACLY activation thus represents a metabolic vulnerability with therapeutic potential for high-risk T-ALL patients.

Bivalent CD47 Immunotoxin for Targeted Therapy of T-Cell Acute Lymphoblastic Leukemia

CD47 is overexpressed on the surface of many types of cancer cells, including T-cell acute lymphoblastic leukemia (T-ALL) cells. In this study, we have developed a diphtheria toxin-based bivalent anti-human CD47 immunotoxin (bi-CD47-IT) for the targeted therapy of CD47+ cancers using a unique diphtheria toxin-resistant yeast Pichia pastoris expression system. Bi-CD47-IT demonstrated compelling in vivo efficacy in multiple T-ALL cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models. Bi-CD47-IT significantly prolonged the median survival of the tumor-bearing mice and highly effectively depleted the T-ALL blast cells in the peripheral blood, spleen, liver, bone marrow, brain, and spinal cord in the T-ALL CDX and PDX mouse models. Bi-CD47-IT cured 60% of tumor-bearing mice in a T-ALL Molt-4 CDX mouse model. Because CD47 is also expressed on normal tissues, including red blood cells and lymphocytes, specificity is a concern. We thus analyzed the in vitro binding avidity and hemagglutination of bi-CD47-IT in human red blood cells, finding no binding or hemagglutination. We further performed a toxicity study of bi-CD47-IT in humanized mice, which showed that bi-CD47-IT transiently depleted the human lymphocytes for ∼4 weeks after the 10-day treatment. No clinical adverse events were observed. As a result, bi-CD47-IT appears to possess the “optimal” binding avidity, with effective binding to human CD47+ T-ALL tumor cells, no binding to human red blood cells and weak binding to human lymphocytes. We believe that bi-CD47-IT is a promising and safe therapeutic drug candidate for the targeted therapy of CD47+ cancers.

The apoptotic and anti-proliferative effects of Neosetophomone B in T-cell acute lymphoblastic leukaemia via PI3K/AKT/mTOR pathway inhibition.

The phosphatidylinositol 3-kinase/Protein Kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway is pivotal in various cancers, including T-cell acute lymphoblastic leukaemia (T-ALL), a particularly aggressive type of leukaemia. This study investigates the effects of Neosetophomone B (NSP-B), a meroterpenoid fungal metabolite, on T-ALL cell lines, focusing on its anti-cancer mechanisms and therapeutic potential. NSP-B significantly inhibited the proliferation of T-ALL cells by inducing G0/G1 cell cycle arrest and promoting caspase-dependent apoptosis. Additionally, NSP-B led to the dephosphorylation and subsequent inactivation of the PI3K/AKT/mTOR signalling pathway, a critical pathway in cell survival and growth. Molecular docking studies revealed a strong binding affinity of NSP-B to the active site of AKT, primarily involving key residues crucial for its activity. Interestingly, NSP-B treatment also induced apoptosis and significantly reduced proliferation in phytohemagglutinin-activated primary human CD3+ T cells, accompanied by a G0/G1 cell cycle arrest. Importantly, NSP-B did not affect normal primary T cells, indicating a degree of selectivity in its action, targeting only T-ALL cells and activated T cells. In conclusion, our findings highlight the potential of NSP-B as a novel therapeutic agent for T-ALL, specifically targeting the aberrantly activated PI3K/AKT/mTOR pathway and being selective in action. These results provide a strong basis for further investigation into NSP-B's anti-cancer properties and potential application in T-ALL clinical therapies.

Andrographolide's Dual Induction of Apoptosis and Ferroptosis Linked to Caspase-3 and FACL4 Regulation in T-Cell Acute Lymphoblastic Leukemia Cells

Andrographolide's Dual Induction of Apoptosis and Ferroptosis Linked to Caspase-3 and FACL4 Regulation in T-Cell Acute Lymphoblastic Leukemia Cells

Transcriptional regulatory program controlled by MYB in T-cell acute lymphoblastic leukemia.

The transcription factor MYB is frequently upregulated in T-cell acute lymphoblastic leukemia (T-ALL), a hematological malignancy originating from T-cell precursors. Here, we demonstrate that MYB plays a crucial role by regulating genes essential for T-ALL pathogenesis. Integrative analysis reveals a long MYB isoform, ENST00000367814.8, which is dominantly expressed and confers a proliferative advantage in T-ALL cells. Rapid depletion of MYB via dTAG-mediated protein degradation affects a large number of genes, which can be classified into early response or late response genes based on their kinetics. Early response genes include many genes involved in hematopoiesis, such as TAL1, RUNX1, GATA3, IKZF2, and CXCR4. Their expression can be recovered at later time-points, suggesting the presence of a negative feedback loop mechanism. In contrast, late response genes, which are continuously downregulated after MYB depletion, includes many genes involved in cell proliferation as well as TAL1 targets, thereby affecting the cellular phenotype.

Aptamer sgc8-Modified PAMAM Nanoparticles for Targeted siRNA Delivery to Inhibit BCL11B in T-Cell Acute Lymphoblastic Leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is a malignant hematological disease with limited targeted therapy options. Overexpression of B-cell lymphoma/leukemia 11B is frequently observed in T-ALL and contributes to leukemogenesis. Knockdown of BCL11B inhibits T-ALL cell proliferation and induces apoptosis, making it a potential therapeutic target. However, the clinical application of siRNA therapies is hindered by challenges such as poor delivery efficiency and limited clinical outcomes. We developed a targeted delivery system for BCL11B siRNA (siBCL11B) using generation 5 polyamidoamine (G5-PAMAM) dendrimers conjugated with the sgc8 aptamer, which specifically binds to the T-ALL cell membrane protein PTK7. This nanoparticle, designated G5-sgc8-siBCL11B, was designed to selectively deliver siRNA to T-ALL cells. In vitro and in vivo experiments were conducted to evaluate its therapeutic efficacy and safety. We demonstrate that sgc8-conjugated siBCL11B nanoparticles selectively and efficiently target BCL11B-overexpressing T-ALL cells, significantly inhibiting cell viability and promoting apoptosis while exhibiting minimal impact on the viability of normal T cells. In T-ALL mouse model studies, G5-sgc8-siBCL11B and G5-siBCL11B significantly inhibited the progression of T-ALL in vivo, extending the survival of mice compared to the control (CTR), G5, and G5-sgc8 groups. Although there was no significant difference in survival between the G5-sgc8-siBCL11B and G5-siBCL11B groups, a trend towards improved survival was observed (p = 0.0993). The G5-sgc8-siBCL11B nanoparticle system demonstrated efficient delivery and significant therapeutic efficacy, highlighting its potential as a promising novel approach for the treatment of T-ALL.

The glutamate/aspartate transporter EAAT1 is crucial for T-cell acute lymphoblastic leukemia proliferation and survival.

T-cell acute lymphoblastic leukemia (T-ALL) is a cancer of the immune system. Approximately 20% of pediatric and 50% of adult T-ALL patients have refractory disease or relapse and die from the disease. To improve patient outcome new therapeutics are needed. With the aim to identify new therapeutic targets, we combined the analysis of T-ALL gene expression and metabolism to identify the metabolic adaptations that T-ALL cells exhibit. We found that glutamine uptake is essential for T-ALL proliferation. Isotope tracing experiments showed that glutamine fuels aspartate synthesis through the tricarboxylic acid cycle and that glutamine and glutamine-derived aspartate together supply three nitrogen atoms in purines and all but one atom in pyrimidine rings. We show that the glutamate-aspartate transporter EAAT1 (SLC1A3), which is normally expressed in the central nervous system, is crucial for glutamine conversion to aspartate and nucleotides and that T-ALL cell proliferation depends on EAAT1 function. Through this work, we identify EAAT1 as a novel therapeutic target for T-ALL treatment.

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.

ALKBH5 promotes T-cell acute lymphoblastic leukemia growth via m6A-guided epigenetic inhibition of miR-20a-5p

This study investigates the role of ALKBH5-mediated m6A demethylation in T-cell acute lymphoblastic leukemia (T-ALL). T-ALL cell lines (HPB-ALL, MOLT4, Jurkat, CCRF-CEM) and human T cells were analyzed. CCRF-CEM and Jurkat cells were transfected with si-ALKBH5, miR-20a-5p-inhibitor, and pcDNA3.1-DDX5. The expression levels of ALKBH5, miR-20a-5p, and DDX5 in these cells were determined using qRT-PCR and Western blotting. Cell viability, proliferation, colony formation, and apoptosis were assessed using CCK-8, EdU staining, colony formation assay, and flow cytometry. mRNA m6A levels were quantified with an m6A RNA methylation detection reagent, and RNA immunoprecipitation was employed to measure the enrichment of DGCR8 and m6A on the primary transcript pri-miR-20a of miR-20a-5p. Dual-luciferase assay confirmed the binding relationship between miR-20a-5p and DDX5. Results showed that ALKBH5 and DDX5 were upregulated in T-ALL tissues and cells, whereas miR-20a-5p was downregulated. Silencing ALKBH5 inhibited T-ALL cell viability, colony formation, and proliferation, while promoting apoptosis. These effects were reversed by miR-20a-5p inhibition or DDX5 overexpression. ALKBH5 reduced the relative m6A level in T-ALL cells and decreased miR-20a-5p expression by reducing DGCR8 binding to pri-miR-20a-5p. miR-20a-5p suppressed DDX5 transcription. In conclusion, ALKBH5-mediated m6A demethylation decreases DGCR8 binding to pri-miR-20a, thereby repressing miR-20a-5p expression and enhancing DDX5 expression, ultimately inhibiting T-ALL cell apoptosis and promoting proliferation.

TARDBP drives T-cell acute lymphoblastic leukemia progression by binding MDM2 mRNA, involving β-catenin pathway.

T-cell acute lymphoblastic leukemia (T-ALL) is a dangerous hematological malignancy. The trans-activation response DNA binding protein (TARDBP), an RNA/DNA binding protein, is involved in the growth and metastasis of multiple cancers. However, TARDBP has not been reported in T-ALL. It was found that TARDBP was highly expressed in pediatric T-ALL samples by microarray GSE26713 (log2 fold change >1, p < .05). Herein, TARDBP was silenced and overexpressed by lentivirus transduction in T-ALL cell lines, including Jurkat and Molt4 cells. Invitro, silencing TARDBP inhibited T-ALL cell proliferation and cycle progression and accelerated cell apoptosis, while overexpressing TARDBP induced the opposite effects. In addition, we investigated whether the β-catenin pathway could be activated by TARDBP in T-ALL cells. Moreover, XAV-939, a β-catenin inhibitor, was capable of suppressing the malignant phenotypes in TARDBP-overexpressed T-ALL cells. Invivo, TARDBP-silenced or TARDBP-overexpressed T-ALL cells were injected into mice. We found that TARDBP promoted T-ALL cell growth in the spleens and bone marrows of mice. On the basis of GSE26713, there was a significant correlation between TARDBP and mouse double minute 2 (MDM2). The RIP-PCR assay demonstrated that TARDBP bound MDM2 mRNA in T-ALL cells. The rescue experiments further revealed the roles of the TARDBP/MDM2 axis in T-ALL cell phenotypes, which was also reflected by mRNA-seq. In aggregate, we explored a promising biomarker, TARDBP, for T-ALL treatment. The underlying mechanisms might involve the interaction with MDM2 mRNA and the regulation of the β-catenin pathway.

Selective Inhibition of Deamidated Triosephosphate Isomerase by Disulfiram, Curcumin, and Sodium Dichloroacetate: Synergistic Therapeutic Strategies for T-Cell Acute Lymphoblastic Leukemia in Jurkat Cells.

T-cell acute lymphoblastic leukemia (T-ALL) is a challenging childhood cancer to treat, with limited therapeutic options and high relapse rates. This study explores deamidated triosephosphate isomerase (dTPI) as a novel therapeutic target. We hypothesized that selectively inhibiting dTPI could reduce T-ALL cell viability without affecting normal T lymphocytes. Computational modeling and recombinant enzyme assays revealed that disulfiram (DS) and curcumin (CU) selectively bind and inhibit dTPI activity without affecting the non-deamidated enzyme. At the cellular level, treatment with DS and CU significantly reduced Jurkat T-ALL cell viability and endogenous TPI enzymatic activity, with no effect on normal T lymphocytes, whereas the combination of sodium dichloroacetate (DCA) with DS or CU showed synergistic effects. Furthermore, we demonstrated that dTPI was present and accumulated only in Jurkat cells, confirming our hypothesis. Finally, flow cytometry confirmed apoptosis in Jurkat cells after treatment with DS and CU or their combination with DCA. These findings strongly suggest that targeting dTPI represents a promising and selective target for T-ALL therapy.

Enhancer looping protein LDB1 modulates MYB expression in T-ALL cell lines in vitro by cooperating with master transcription factors

BackgroundDespite significant progress in the prognosis of pediatric T-cell acute lymphoblastic leukemia (T-ALL) in recent decades, a notable portion of children still confronts challenges such as treatment resistance and recurrence, leading to limited options and a poor prognosis. LIM domain-binding protein 1 (LDB1) has been confirmed to exert a crucial role in various physiological and pathological processes. In our research, we aim to elucidate the underlying function and mechanisms of LDB1 within the background of T-ALL.MethodsEmploying short hairpin RNA (shRNA) techniques, we delineated the functional impact of LDB1 in T-ALL cell lines. Through the application of RNA-Seq, CUT&Tag, and immunoprecipitation assays, we scrutinized master transcription factors cooperating with LDB1 and identified downstream targets under LDB1 regulation.ResultsLDB1 emerges as a critical transcription factor co-activator in cell lines derived from T-ALL. It primarily collaborates with master transcription factors (ERG, ETV6, IRF1) to cooperatively regulate the transcription of downstream target genes. Both in vitro and in vivo experiments affirm the essential fuction of LDB1 in the proliferation and survival of cell lines derived from T-ALL, with MYB identified as a significant downstream target of LDB1.ConclusionsTo sum up, our research establishes the pivotal fuction of LDB1 in the tumorigenesis and progression of T-ALL cell lines. Mechanistic insights reveal that LDB1 cooperates with ERG, ETV6, and IRF1 to modulate the expression of downstream effector genes. Furthermore, LDB1 controls MYB through remote enhancer modulation, providing valuable mechanistic insights into its involvement in the progression of T-ALL.

The DHODH inhibitor teriflunomide impedes cell proliferation and enhances chemosensitivity to daunorubicin (DNR) in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological tumor that requires novel treatment strategies, especially for relapsed/refractory cases. Dihydroorotate dehydrogenase (DHODH), a key enzyme in the de novo pyrimidine synthesis pathway, has been identified as a potential target for tumors. Besides, Teriflunomide (TRF) is a DHODH inhibitor with anticancer effects; however, its role in T-ALL remains poorly understood. Here, we investigated the potential anticancer effects of TRF on T-ALL cells, and the results showed that TRF inhibited cell proliferation, caused S-phase cell cycle arrest, and promoted apoptosis of T-ALL (MOLT4 and JURKAT) cell lines. In addition, TRF reduced the infiltration capacity of T-ALL cells in T-ALL xenograft mice while up-regulating the expression of P53 and BTG2. The BTG2 knockdown significantly attenuated the inhibitory effect of TRF on cellular growth and suppressed the TRF-mediated elevated expression of P53 in T-ALL cells. Moreover, combined treatment with TRF and daunorubicin (DNR) significantly reduced cell viability and promoted apoptosis in DNR-resistant T-ALL cells. Our study provides valuable insights into the critical role of TRF in treating T-ALL while increasing the sensitivity of DNR-resistant T-ALL cells to DNR.

C-C Chemokine Receptor 7 Promotes T-Cell Acute Lymphoblastic Leukemia Invasion of the Central Nervous System via β2-Integrins.

C-C Chemokine Receptor 7 (CCR7) mediates T-cell acute lymphoblastic leukemia (T-ALL) invasion of the central nervous system (CNS) mediated by chemotactic migration to C-C chemokine ligand 19 (CCL19). To determine if a CCL19 antagonist, CCL198-83, could inhibit CCR7-induced chemotaxis and signaling via CCL19 but not CCL21, we used transwell migration and Ca2+ mobilization signaling assays. We found that in response to CCL19, human T-ALL cells employ β2 integrins to invade human brain microvascular endothelial cell monolayers. In vivo, using an inducible mouse model of T-ALL, we found that we were able to increase the survival of the mice treated with CCL198-83 when compared to non-treated controls. Overall, our results describe a targetable cell surface receptor, CCR7, which can be inhibited to prevent β2-integrin-mediated T-ALL invasion of the CNS and potentially provides a platform for the pharmacological inhibition of T-ALL cell entry into the CNS.

QRICH1 suppresses pediatric T-cell acute lymphoblastic leukemia by inhibiting GRP78

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that commonly affects children and adolescents with a poor prognosis. The terminal unfolded protein response (UPR) is an emerging anti-cancer approach, although its role in pediatric T-ALL remains unclear. In our pediatric T-ALL cohort from different centers, a lower QRICH1 expression was found associated with a worse prognosis of pediatric T-ALL. Overexpression of QRICH1 significantly inhibited cell proliferation and stimulated apoptosis of T-ALL both in vitro and in vivo. Upregulation of QRICH1 significantly downregulated 78 KDa glucose-regulated protein (GRP78) and upregulated CHOP, thus activating the terminal UPR. Co-overexpression of GRP78 in T-ALL cells overexpressing QRICH1 partially reverted the inhibited proliferation and stimulated apoptosis. QRICH1 bound to the residues Asp212 and Glu155 of the nucleotide-binding domain (NBD) of GRP78, thereby inhibiting its ATP hydrolysis activity. In addition, QRICH1 was associated with endoplasmic reticulum (ER) stress in T-ALL, and overexpression of QRICH1 reversed drug resistance. Overall, low QRICH1 expression is an independent risk factor for a poor prognosis of pediatric T-ALL. By inhibiting GRP78, QRICH1 suppresses pediatric T-ALL.

Fratricide-resistant CD7-CAR T cells in T-ALL.

T cell acute lymphoblastic leukemia (T-ALL) is difficult to treat when it relapses after therapy or is chemoresistant; the prognosis of patients with relapsed or refractory T-ALL is generally poor. We report a case series of 17 such patients who received autologous chimeric antigen receptor (CAR) T cells expressing an anti-CD7 CAR and an anti-CD7 protein expression blocker (PEBL), which prevented CAR T cell fratricide. Despite high leukemic burden and low CAR T cell dosing, 16 of the 17 patients attained minimal residual disease-negative complete remission within 1 month. The remaining patient had CD7- T-ALL cells before infusion, which persisted after infusion. Toxicities were mild: cytokine release syndrome grade 1 in ten patients and grade 2 in three patients; immune effector cell-associated neurotoxicity syndrome grade 1 in two patients. Eleven patients remained relapse-free (median follow-up, 15 months), including all nine patients who received an allotransplant. The first patient is in remission 55 months after infusion without further chemotherapy or transplantation; circulating CAR T cells were detectable for 2 years. T cells regenerating after lymphodepletion lacked CD7 expression, were polyclonal and responded to SARS-CoV-2 vaccination; CD7+ immune cells reemerged concomitantly with CAR T cell disappearance. In conclusion, autologous anti-CD7 PEBL-CAR T cells have powerful antileukemic activity and are potentially an effective option for the treatment of T-ALL.