A retrospective study of an irradiation-based conditioning regimen and chidamide maintenance therapy in T-ALL/LBL.

OBJECTIVES: T-cell acute lymphoblastic leukemia/lymphoblastic lymphoma (T-ALL/LBL) are highly malignant and aggressive hematologic tumors for which there is no standard first-line treatment. Chidamide, a novel histone deacetylase inhibitor, shows great promise. We assessed the efficacy and safety of an irradiation-containing conditioning regimen for allogeneic hematopoietic stem cell transplantation (allo-HSCT) and post-transplantation chidamide maintenance in patients with T-ALL/LBL. METHODS: We retrospectively analyzed the clinical data of six patients with T-ALL/LBL who underwent allo-HSCT with a radiotherapy-containing pretreatment regimen and post-transplant chidamide maintenance therapy. The endpoints were relapse, graft-versus-host disease (GVHD), transplant-related mortality (TRM), progression-free survival (PFS), overall survival (OS), and adverse events (AEs). RESULTS: All of the patients had uneventful post-transplant hematopoietic reconstitution, and all achieved complete molecular remission within 30 days. All six patients survived, and two relapsed with a median relapse time of 828.5 (170-1335) days. The 1-year OS rate was 100%, the 2-year PFS rate was 66.7%, and the TRM rate was 0%. After transplantation, two patients developed grade I-II acute GVHD (2/6); grade III-IV acute and chronic GVHD were not observed. The most common AEs following chidamide administration were hematological AEs, which occurred to varying degrees in all patients; liver function abnormalities occurred in two patients (grade 2), and symptoms of malaise occurred in one patient (grade 1). CONCLUSION: Chidamide maintenance therapy after T-ALL/LBL transplantation is safe, but the efficacy needs to be further investigated.

Case report: Preventive infusion of donor-derived CD7 chimeric antigen receptor T cells after allogeneic hematopoietic stem cell transplantation.

Chimeric antigen receptor T cells (CAR T) targeting CD7 for T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) showed promising efficacy and safety in some clinical trials. However, most of them were bridged with allogeneic hematopoietic stem cell transplantation (allo-HSCT). We described successful treatment with preventive donor-derived anti-CD7 CAR-T therapy in a case of refractory T lymphoblastic lymphoma following allo-HSCT, who could not receive autologous anti-CD7 CAR-T products due to the low-quality of T lymphocytes. To date, the patient's complete remission has persisted for 20 months after HSCT.

Valrubicin-loaded immunoliposomes for specific vesicle-mediated cell death in the treatment of hematological cancers.

We created valrubicin-loaded immunoliposomes (Val-ILs) using the antitumor prodrug valrubicin, a hydrophobic analog of daunorubicin. Being lipophilic, valrubicin readily incorporated Val-lLs that were loaded with specific antibodies. Val-ILs injected intravenously rapidly reached the bone marrow and spleen, indicating their potential to effectively target cancer cells in these areas. Following the transplantation of human pediatric B-cell acute lymphoblastic leukemia (B-ALL), T-cell acute lymphoblastic leukemia (T-ALL), or acute myeloid leukemia (AML) in immunodeficient NSG mice, we generated patient-derived xenograft (PDX) models, which were treated with Val-ILs loaded with antibodies to target CD19, CD7 or CD33. Only a small amount of valrubicin incorporated into Val-ILs was needed to induce leukemia cell death in vivo, suggesting that this approach could be used to efficiently treat acute leukemia cells. We also demonstrated that Val-ILs could reduce the risk of contamination of CD34+ hematopoietic stem cells by acute leukemia cells during autologous peripheral blood stem cell transplantation, which is a significant advantage for clinical applications. Using EL4 lymphoma cells on immunocompetent C57BL/6 mice, we also highlighted the potential of Val-ILs to target immunosuppressive cell populations in the spleen, which could be valuable in impairing cancer cell expansion, particularly in lymphoma cases. The most efficient Val-ILs were found to be those loaded with CD11b or CD223 antibodies, which, respectively, target the myeloid-derived suppressor cells (MDSC) or the lymphocyte-activation gene 3 (LAG-3 or CD223) on T4 lymphocytes. This study provides a promising preclinical demonstration of the effectiveness and ease of preparation of Val-ILs as a novel nanoparticle technology. In the context of hematological cancers, Val-ILs have the potential to be used as a precise and effective therapy based on targeted vesicle-mediated cell death.

Intracranial residual lesions following early intensification in a patient with T-cell acute lymphoblastic leukemia: a case report.

BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) tends to involve central nervous system (CNS) infiltration at diagnosis. However, cases of residual CNS lesions detected at the end of induction and post early intensification have not been recorded in patients with T-ALL. Also, the ratio and prognosis of patients with residual intracranial lesions have not been defined. CASE PRESENTATION: A 9-year-old boy with T-ALL had multiple intracranial tumors, which were still detected post early intensification. To investigate residual CNS lesions, we used 11C-methionine (MET)-positron emission tomography. Negative MET uptake in CNS lesions and excellent MRD status in bone marrow allowed continuing therapies without hematopoietic cell transplantation. CONCLUSIONS: In cases with residual lesions on imaging studies, treatment strategies should be considered by the systemic response, direct assessment of spinal fluid, along with further development of noninvasive imaging methods in CNS. Further retrospective or prospective studies are required to determine the prognosis and frequency of cases with residual intracranial lesions after induction therapy.

[Prognostic analysis of childhood T-lymphoblastic lymphoma treated with leukemia regimen]. / 儿童Tæ·‹å·´æ¯ç»†èƒžæ·‹å·´ç˜¤é‡‡ç”¨ç™½è¡€ç— æ–¹æ¡ˆæ²»ç–—çš„é¢„åŽåˆ†æž.

OBJECTIVES: To investigate the prognosis of childhood T-lymphoblastic lymphoma (T-LBL) treated with acute lymphoblastic leukemia (ALL) regimen and related influencing factors. METHODS: A retrospective analysis was performed for the prognostic characteristics of 29 children with T-LBL who were treated with ALL regimen (ALL-2009 or CCCG-ALL-2015 regimen) from May 2010 to May 2022. RESULTS: The 29 children with T-LBL had a 5-year overall survival (OS) rate of 84%±7% and an event-free survival (EFS) rate of 81%±8%. The children with B systemic symptoms (unexplained fever >38°C for more than 3 days; night sweats; weight loss >10% within 6 months) at initial diagnosis had a lower 5-year EFS rate compared to the children without B symptoms (P<0.05). The children with platelet count >400×109/L and involvement of both mediastinum and lymph nodes at initial diagnosis had lower 5-year OS rates (P<0.05). There were no significant differences in 5-year OS and EFS rates between the children treated with CCCG-ALL-2015 regimen and those treated with ALL-2009 regimen (P>0.05). Compared with the ALL-2009 regimen, the CCCG-ALL-2015 regimen reduced the frequency of high-dose methotrexate chemotherapy and the incidence rate of severe infections (P<0.05). CONCLUSIONS: The ALL regimen is safe and effective in children with T-LBL. Children with B systemic symptoms, platelet count >400×109/L, and involvement of both mediastinum and lymph nodes at initial diagnosis tend to have a poor prognosis. Reduction in the frequency of high-dose methotrexate chemotherapy can reduce the incidence rate of severe infections, but it does not affect prognosis.

Hyperactive STAT5 hijacks T cell receptor signaling and drives immature T cell acute lymphoblastic leukemia.

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive immature T cell cancer. Mutations in IL7R have been analyzed genetically, but downstream effector functions such as STAT5A and STAT5B hyperactivation are poorly understood. Here, we studied the most frequent and clinically challenging STAT5BN642H driver in T cell development and immature T cell cancer onset and compared it with STAT5A hyperactive variants in transgenic mice. Enhanced STAT5 activity caused disrupted T cell development and promoted an early T cell progenitor-ALL phenotype, with upregulation of genes involved in T cell receptor (TCR) signaling, even in absence of surface TCR. Importantly, TCR pathway genes were overexpressed in human T-ALL and mature T cell cancers and activation of TCR pathway kinases was STAT5 dependent. We confirmed STAT5 binding to these genes using ChIP-Seq analysis in human T-ALL cells, which were sensitive to pharmacologic inhibition by dual STAT3/5 degraders or ZAP70 tyrosine kinase blockers in vitro and in vivo. We provide genetic and biochemical proof that STAT5A and STAT5B hyperactivation can initiate T-ALL through TCR pathway hijacking and suggest similar mechanisms for other T cell cancers. Thus, STAT5 or TCR component blockade are targeted therapy options, particularly in patients with chemoresistant clones carrying STAT5BN642H.

A case of T-cell acute lymphoblastic leukemia in retroviral gene therapy for ADA-SCID.

Hematopoietic stem cell gene therapy (GT) using a γ-retroviral vector (γ-RV) is an effective treatment for Severe Combined Immunodeficiency due to Adenosine Deaminase deficiency. Here, we describe a case of GT-related T-cell acute lymphoblastic leukemia (T-ALL) that developed 4.7 years after treatment. The patient underwent chemotherapy and haploidentical transplantation and is currently in remission. Blast cells contain a single vector insertion activating the LIM-only protein 2 (LMO2) proto-oncogene, confirmed by physical interaction, and low Adenosine Deaminase (ADA) activity resulting from methylation of viral promoter. The insertion is detected years before T-ALL in multiple lineages, suggesting that further hits occurred in a thymic progenitor. Blast cells contain known and novel somatic mutations as well as germline mutations which may have contributed to transformation. Before T-ALL onset, the insertion profile is similar to those of other ADA-deficient patients. The limited incidence of vector-related adverse events in ADA-deficiency compared to other γ-RV GT trials could be explained by differences in transgenes, background disease and patient's specific factors.

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.

Wiskott Aldrich syndrome protein (WASp)-deficient Th1 cells promote R-loop-driven transcriptional insufficiency and transcription-coupled nucleotide excision repair factor (TC-NER)-driven genome-instability in the pathogenesis of T cell acute lymphoblastic leukemia.

BACKGROUND: T-ALL is an aggressive hematological tumor that develops as the result of a multi-step oncogenic process which causes expansion of hematopoietic progenitors that are primed for T cell development to undergo malignant transformation and growth. Even though first-line therapy has a significant response rate, 40% of adult patients and 20% of pediatric patients will relapse. Therefore, there is an unmet need for treatment for relapsed/refractory T-ALL to develop potential targeted therapies. METHODS: Pediatric T-ALL patient derived T cells were grown under either nonskewingTh0 or Th1-skewing conditions to further process for ChIP-qPCR, RDIP-qPCR and other RT-PCR assays. Endogenous WASp was knocked out using CRISPR-Cas9 and was confirmed using flow cytometry and western blotting. LC-MS/MS was performed to find out proteomic dataset of WASp-interactors generated from Th1-skewed, human primary Th-cells. DNA-damage was assessed by immunofluorescence confocal-imaging and single-cell gel electrophoresis (comet assay). Overexpression of RNaseH1 was also done to restore normal Th1-transcription in WASp-deficient Th1-skewed cells. RESULTS: We discovered that nuclear-WASp is required for suppressing R-loop production (RNA/DNA-hybrids) at Th1-network genes by ribonucleaseH2 (RNH2) and topoisomerase1. Nuclear-WASp is associated with the factors involved in preventing and dissolving R-loops in Th1 cells. In nuclear- WASp-reduced malignant Th1-cells, R-loops accumulate in vivo and are processed into DNA-breaks by transcription-coupled-nucleotide-excision repair (TC-NER). Several epigenetic modifications were also found to be involved at Th1 gene locus which are responsible for active/repressive marks of particular genes. By demonstrating WASp as a physiologic regulator of programmed versus unprogrammed R-loops, we suggest that the transcriptional role of WASp in vivo extends also to prevent transcription-linked DNA damage during malignancy and through modification of epigenetic dysregulations. CONCLUSION: Our findings present a provocative possibility of resetting R-loops as a therapeutic intervention to correct both immune deficiency and malignancy in T-cell acute lymphoblastic leukemia patients and a novel role of WASp in the epigenetic regulation of T helper cell differentiation in T-ALL patients, anticipating WASp's requirement for the suppression of T-ALL progression.

The CNS microenvironment promotes leukemia cell survival by disrupting tumor suppression and cell cycle regulation in pediatric T-cell acute lymphoblastic leukemia.

A major obstacle in improving survival in pediatric T-cell acute lymphoblastic leukemia is understanding how to predict and treat leukemia relapse in the CNS. Leukemia cells are capable of infiltrating and residing within the CNS, primarily the leptomeninges, where they interact with the microenvironment and remain sheltered from systemic treatment. These cells can survive in the CNS, by hijacking the microenvironment and disrupting normal functions, thus promoting malignant transformation. While the protective effects of the bone marrow niche have been widely studied, the mechanisms behind leukemia infiltration into the CNS and the role of the CNS niche in leukemia cell survival remain unknown. We identified a dysregulated gene expression profile in CNS infiltrated T-ALL and CNS relapse, promoting cell survival, chemoresistance, and disease progression. Furthermore, we discovered that interactions between leukemia cells and human meningeal cells induced epigenetic alterations, such as changes in histone modifications, including H3K36me3 levels. These findings are a step towards understanding the molecular mechanisms promoting leukemia cell survival in the CNS microenvironment. Our results highlight genetic and epigenetic alterations induced by interactions between leukemia cells and the CNS niche, which could potentially be utilized as biomarkers to predict CNS infiltration and CNS relapse.

A Rare Case of Methemoglobinemia after Ifosfamide Infusion in a 3-Year-Old Patient Treated for T-ALL.

Methemoglobinemia is a potentially life-threatening, rare condition in which the oxygen-carrying capacity of hemoglobin is diminished. We present the case of a 3-year-old boy treated for T-cell acute lymphoblastic leukemia (T-ALL) who developed methemoglobinemia (MetHb 57.1%) as a side effect of ifosfamide administration. Due to his critical condition, the patient was transferred to the intensive care unit (ICU). The therapy included methylene blue administration, an exchange transfusion, catecholamine infusion, and steroids. Improving the general condition allowed for continuing chemotherapy without ifosfamide and completion of the HR2 block. Vigilance for methemoglobinemia as a very rare side effect should be widespread when using ifosfamide in the treatment protocols.

Metabolic Profiling as an Approach to Differentiate T-Cell Acute Lymphoblastic Leukemia Cell Lines Belonging to the Same Genetic Subgroup.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive tumor mainly affecting children and adolescents. It is driven by multiple genetic mutations that together define the leukemic phenotype. Interestingly, based on genetic alterations and/or deregulated expression, at least six genetic subgroups have been recognized. The TAL/LMO subgroup is one of the most represented genetic subgroups, characterizing 30-45% of pediatric T-ALL cases. The study of lipid and metabolic profiles is increasingly recognized as a valuable tool for comprehending the development and progression of tumors. In this study, metabolic and lipidomic analysis via LC/MS have been carried out on four T-ALL cell lines belonging to the TAL/LMO subgroup (Jurkat, Molt-4, Molt-16, and CCRF-CEM) to identify new potential metabolic biomarkers and to provide a subclassification of T-ALL cell lines belonging to the same subgroup. A total of 343 metabolites were annotated, including 126 polar metabolites and 217 lipid molecules. The statistical analysis, for both metabolic and lipid profiles, shows significant differences and similarities among the four cell lines. The Molt-4 cell line is the most distant cell line and CCRF-CEM shows a high activity in specific pathways when compared to the other cell lines, while Molt-16 and Jurkat show a similar metabolic profile. Additionally, this study highlighted the pathways that differ in each cell line and the possible enzymes involved using bioinformatic tools, capable of predicting the pathways involved by studying the differences in the metabolic profiles. This experiment offers an approach to differentiate T-ALL cell lines and could open the way to verify and confirm the obtained results directly in patients.

Honokiol induces apoptosis and autophagy in dexamethasone-resistant T-acute lymphoblastic leukemia CEM-C1 cells.

Objective: To study whether and, if so, how honokiol overcome dexamethasone resistance in DEX-resistant CEM-C1 cells. Methods: We investigated the effect of honokiol (0-20 µM) on cell proliferation, cell cycle, cell apoptosis and autophagy in DEX-resistant CEM-C1 cells and DEX-sensitive CEM-C7 cells. We also determined the role of c-Myc protein and mRNA in the occurrence of T-ALL associated dexamethasone resistance western blot and reverse transcription-qPCR (RT-qPCR) analysis. Results: Cell Counting Kit (CCK)-8 assay shows that DEX-resistant CEM-C1 cell lines were highly resistant to dexamethasone with IC50 of 364.1 ± 29.5 µM for 48 h treatment. However, upon treatment with dexamethasone in combination with 1.5 µM of honokiol for 48 h, the IC50 of CEM-C1 cells significantly decreased to 126.2 ± 12.3 µM, and the reversal fold was 2.88. Conversely, the IC50 of CEM-C7 cells was not changed combination of dexamethasone and honokiol as compared to that of CEM-C7 cells treated with dexamethasone alone. It has been shown that honokiol induced T-ALL cell growth inhibition by apoptosis and autophagy via downregulating cell cycle-regulated proteins (Cyclin E, CDK4, and Cyclin D1) and anti-apoptotic proteins BCL-2 and upregulating pro-apoptotic proteins Bax and led to PARP cleavage. Honokiol may overcome dexamethasone resistance in DEX-resistant CEM-C1 cell lines via the suppression of c-Myc mRNA expression. Conclusion: The combination of honokiol and DEX were better than DEX alone in DEX-resistant CEM-C1 cell lines. Honokiol may regulate T-ALL-related dexamethasone resistance by affecting c-Myc.

Integrated analysis of transcriptome and genome variations in pediatric T cell acute lymphoblastic leukemia: data from north Indian tertiary care center.

INTRODUCTION: T-cell acute lymphoblastic leukemia (T-ALL) is a genetically heterogeneous disease with poor prognosis and inferior outcome. Although multiple studies have been perform on genomics of T-ALL, data from Indian sub-continent is scarce. METHODS: In the current study we aimed to identify the genetic variability of T-ALL in an Indian cohort of pediatric (age ≤ 12 years) T-ALL patients (n = 25) by whole transcriptome sequencing along with whole exome sequencing and correlated the findings with clinical characteristics and disease outcome. RESULTS: The median age was 7 years (range 3 -12 years). RNA sequencing revealed a definitive fusion event in 14 cases (56%) (including a novel fusions) with STIL::TAL1 in 4 (16%), followed by NUP21::ABL1, TCF7::SPI1, ETV6::HDAC8, LMO1::RIC3, DIAPH1::JAK2, SETD2::CCDC12 and RCBTB2::LPAR6 in 1 (4%) case each. Significant aberrant expression was noted in RAG1 (64%), RAG2 (80%), MYCN (52%), NKX3-1 (52%), NKX3-2 (32%), TLX3 (28%), LMO1 (20%) and MYB (16%) genes. WES data showed frequent mutations in NOTCH1 (35%) followed by WT1 (23%), FBXW7 (12%), KRAS (12%), PHF6 (12%) and JAK3 (12%). Nearly 88.2% of cases showed a deletion of CDKN2A/CDKN2B/MTAP genes. Clinically significant association of a better EFS and OS (p=0.01) was noted with RAG2 over-expression at a median follow up of 22 months, while a poor EFS (p=0.041) and high relapse rate (p=0.045) was observed with MYB over-expression. CONCLUSION: Overall, the present study demonstrates the frequencies of transcriptomic and genetic alterations from Indian cohort of pediatric T-ALL and is a salient addition to current genomics data sets available in T-ALL.

The role of quiescent thymic progenitors in TAL/LMO2-induced T-ALL chemotolerance.

Relapse in T-cell acute lymphoblastic leukemia (T-ALL) may signify the persistence of leukemia-initiating cells (L-ICs). Ectopic TAL1/LMO expression defines the largest subset of T-ALL, but its role in leukemic transformation and its impact on relapse-driving L-ICs remain poorly understood. In TAL1/LMO mouse models, double negative-3 (DN3; CD4-CD8-CD25+CD44-) thymic progenitors harbored L-ICs. However, only a subset of DN3 leukemic cells exhibited L-IC activity, and studies linking L-ICs and chemotolerance are needed. To investigate L-IC heterogeneity, we used mouse models and applied single-cell RNA-sequencing and nucleosome labeling techniques in vivo. We identified a DN3 subpopulation with a cell cycle-restricted profile and heightened TAL1/LMO2 activity, that expressed genes associated with stemness and quiescence. This dormant DN3 subset progressively expanded throughout leukemogenesis, displaying intrinsic chemotolerance and enrichment in genes linked to minimal residual disease. Examination of TAL/LMO patient samples revealed a similar pattern in CD7+CD1a- thymic progenitors, previously recognized for their L-IC activity, demonstrating cell cycle restriction and chemotolerance. Our findings substantiate the emergence of dormant, chemotolerant L-ICs during leukemogenesis, and demonstrate that Tal1 and Lmo2 cooperate to promote DN3 quiescence during the transformation process. This study provides a deeper understanding of TAL1/LMO-induced T-ALL and its clinical implications in therapy failure.

Targeting the TNF/IAP pathway synergizes with anti-CD3 immunotherapy in T-cell acute lymphoblastic leukemia.

ABSTRACT: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy. Current treatments, based on intensive chemotherapy regimens provide overall survival rates of ∼85% in children and <50% in adults, calling the search of new therapeutic options. We previously reported that targeting the T-cell receptor (TCR) in T-ALL with anti-CD3 (αCD3) monoclonal antibodies (mAbs) enforces a molecular program akin to thymic negative selection, a major developmental checkpoint in normal T-cell development; induces leukemic cell death; and impairs leukemia progression to ultimately improve host survival. However, αCD3 monotherapy resulted in relapse. To find out actionable targets able to re-enforce leukemic cells' vulnerability to αCD3 mAbs, including the clinically relevant teplizumab, we identified the molecular program induced by αCD3 mAbs in patient-derived xenografts derived from T-ALL cases. Using large-scale transcriptomic analysis, we found prominent expression of tumor necrosis factor α (TNFα), lymphotoxin α (LTα), and multiple components of the "TNFα via NF-κB signaling" pathway in anti-CD3-treated T-ALL. We show in vivo that etanercept, a sink for TNFα/LTα, enhances αCD3 antileukemic properties, indicating that TNF/TNF receptor (TNFR) survival pathways interferes with TCR-induced leukemic cell death. However, suppression of TNF-mediated survival and switch to TNFR-mediated cell death through inhibition of cellular inhibitor of apoptosis protein-1/2 (cIAP1/2) with the second mitochondrial-derived activator of caspases (SMAC) mimetic birinapant synergizes with αCD3 to impair leukemia expansion in a receptor-interacting serine/threonine-protein kinase 1-dependent manner and improve mice survival. Thus, our results advocate the use of either TNFα/LTα inhibitors, or birinapant/other SMAC mimetics to improve anti-CD3 immunotherapy in T-ALL.