RESUMO
BACKGROUND: Relapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen. METHODS: In this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy. RESULTS: The 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72-98) and 88% (95% CI: 67-96); ≥ CR2 were 81% (95% CI: 61-92) and 68% (95% CI: 47-82) and refractory disease were 32% (95% CI: 11-54) and 20% (95% CI: 6-40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64-87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/µL and 140/µL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035). CONCLUSION: The combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population. The trial is registered at ClinicalTrials.gov (NCT01807611).
Assuntos
Neoplasias Hematológicas , Transplante de Células-Tronco Hematopoéticas , Células Matadoras Naturais , Células T de Memória , Condicionamento Pré-Transplante , Transplante Haploidêntico , Humanos , Feminino , Masculino , Células Matadoras Naturais/transplante , Células Matadoras Naturais/imunologia , Criança , Adolescente , Transplante Haploidêntico/métodos , Pré-Escolar , Transplante de Células-Tronco Hematopoéticas/métodos , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Condicionamento Pré-Transplante/métodos , Neoplasias Hematológicas/terapia , Doença Enxerto-Hospedeiro/prevenção & controle , Doença Enxerto-Hospedeiro/etiologia , Lactente , Adulto Jovem , Adulto , Resultado do Tratamento , Efeito Enxerto vs LeucemiaRESUMO
Hematopoiesis is an essential process for organismal development and homeostasis. Epigenetic regulation of gene expression is critical for stem cell self-renewal and differentiation in normal hematopoiesis. Increasing evidence shows that disrupting the balance between self-renewal and cell fate decisions can give rise to hematological diseases such as bone marrow failure and leukemia. Consequently, next-generation sequencing studies have identified various aberrations in histone modifications, DNA methylation, RNA splicing, and RNA modifications in hematologic diseases. Favorable outcomes after targeting epigenetic regulators during disease states have further emphasized their importance in hematological malignancy. However, these targeted therapies are only effective in some patients, suggesting that further research is needed to decipher the complexity of epigenetic regulation during hematopoiesis. In this review, an update on the impact of the epigenome on normal hematopoiesis, disease initiation and progression, and current therapeutic advancements will be discussed.
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RNA splicing factor SF3B1 is recurrently mutated in various cancers, particularly in hematologic malignancies. We previously reported that coexpression of Sf3b1 mutation and Atm deletion in B cells, but not either lesion alone, leads to the onset of chronic lymphocytic leukemia (CLL) with CLL cells harboring chromosome amplification. However, the exact role of Sf3b1 mutation and Atm deletion in chromosomal instability (CIN) remains unclear. Here, we demonstrated that SF3B1 mutation promotes centromeric R-loop (cen-R-loop) accumulation, leading to increased chromosome oscillation, impaired chromosome segregation, altered spindle architecture, and aneuploidy, which could be alleviated by removal of cen-R-loop and exaggerated by deletion of ATM. Aberrant splicing of key genes involved in R-loop processing underlay augmentation of cen-R-loop, as overexpression of the normal isoform, but not the altered form, mitigated mitotic stress in SF3B1-mutant cells. Our study identifies a critical role of splice variants in linking RNA splicing dysregulation and CIN and highlights cen-R-loop augmentation as a key mechanism for leukemogenesis.
Assuntos
Leucemia Linfocítica Crônica de Células B , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Estruturas R-Loop , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Mutação , Fatores de Processamento de RNA/genética , Fatores de Processamento de RNA/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia/metabolismoRESUMO
Rearrangments in Histone-lysine-N-methyltransferase 2A (KMT2Ar) are associated with pediatric, adult and therapy-induced acute leukemias. Infants with KMT2Ar acute lymphoblastic leukemia (ALL) have a poor prognosis with an event-free-survival of 38%. Herein we evaluate 1116 FDA approved compounds in primary KMT2Ar infant ALL specimens and identify a sensitivity to proteasome inhibition. Upon exposure to this class of agents, cells demonstrate a depletion of histone H2B monoubiquitination (H2Bub1) and histone H3 lysine 79 dimethylation (H3K79me2) at KMT2A target genes in addition to a downregulation of the KMT2A gene expression signature, providing evidence that it targets the KMT2A transcriptional complex and alters the epigenome. A cohort of relapsed/refractory KMT2Ar patients treated with this approach on a compassionate basis had an overall response rate of 90%. In conclusion, we report on a high throughput drug screen in primary pediatric leukemia specimens whose results translate into clinically meaningful responses. This innovative treatment approach is now being evaluated in a multi-institutional upfront trial for infants with newly diagnosed ALL.
Assuntos
Leucemia-Linfoma Linfoblástico de Células Precursoras , Complexo de Endopeptidases do Proteassoma , Lactente , Adulto , Humanos , Criança , Complexo de Endopeptidases do Proteassoma/genética , Lisina/genética , Proteína de Leucina Linfoide-Mieloide/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , TranscriptomaRESUMO
Acute myeloid leukemia (AML) is a hematopoietic malignancy with poor prognosis and limited treatment options. Here we provide a comprehensive census of the bone marrow immune microenvironment in adult and pediatric patients with AML. We characterize unique inflammation signatures in a subset of AML patients, associated with inferior outcomes. We identify atypical B cells, a dysfunctional B-cell subtype enriched in patients with high-inflammation AML, as well as an increase in CD8+GZMK+ and regulatory T cells, accompanied by a reduction in T-cell clonal expansion. We derive an inflammation-associated gene score (iScore) that associates with poor survival outcomes in patients with AML. Addition of the iScore refines current risk stratifications for patients with AML and may enable identification of patients in need of more aggressive treatment. This work provides a framework for classifying patients with AML based on their immune microenvironment and a rationale for consideration of the inflammatory state in clinical settings.
Assuntos
Leucemia Mieloide Aguda , Adulto , Humanos , Criança , Leucemia Mieloide Aguda/genética , Medula Óssea/patologia , Linfócitos T Reguladores/patologia , Inflamação/patologia , Medição de Risco , Microambiente TumoralRESUMO
Hematopoietic stem and progenitor cells (HSPCs) sustain lifelong hematopoiesis. Mutations of pre-mRNA splicing machinery, especially splicing factor 3b, subunit 1 (SF3B1), are early lesions found in malignancies arising from HSPC dysfunction. However, why splicing factor deficits contribute to HSPC defects remains incompletely understood. Using zebrafish, we show that HSPC formation in sf3b1 homozygous mutants is dependent on STAT3 activation. Clinically, mutations in SF3B1 are heterozygous; thus, we explored if targeting STAT3 could be a vulnerability in these cells. We show that SF3B1 heterozygosity confers heightened sensitivity to STAT3 inhibition in zebrafish, mouse, and human HSPCs. Cells carrying mutations in other splicing factors or treated with splicing modulators are also more sensitive to STAT3 inhibition. Mechanistically, we illustrate that STAT3 inhibition exacerbates aberrant splicing in SF3B1 mutant cells. Our findings reveal a conserved vulnerability of splicing factor mutant HSPCs that could allow for their selective targeting in hematologic malignancies.
Assuntos
Hematopoese , Peixe-Zebra , Camundongos , Humanos , Animais , Fatores de Processamento de RNA/genética , Fatores de Processamento de RNA/metabolismo , Peixe-Zebra/metabolismo , Hematopoese/genética , Splicing de RNA/genética , Células-Tronco Hematopoéticas/metabolismo , Mutação/genética , Fosfoproteínas/metabolismo , Fator de Transcrição STAT3/genéticaRESUMO
Childhood cancer survivors exposed to chemotherapy show signs of accelerated aging and are at risk of developing secondary malignancies; however, the mechanisms responsible for these long-term adverse effects are not clear. In a recent study, Bertrums et al. show that exposure to chemotherapy results in an increase in mutational age of normal hematopoietic stem cells.
Assuntos
Sobreviventes de Câncer , Segunda Neoplasia Primária , Neoplasias , Envelhecimento , Criança , Humanos , Neoplasias/tratamento farmacológico , Segunda Neoplasia Primária/etiologia , Segunda Neoplasia Primária/genética , SobreviventesRESUMO
While adult bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs) and their extrinsic regulation is well studied, little is known about the composition, function, and extrinsic regulation of the first HSPCs to enter the BM during development. Here, we functionally interrogate murine BM HSPCs from E15.5 through P0. Our work reveals that fetal BM HSPCs are present by E15.5, but distinct from the HSPC pool seen in fetal liver, both phenotypically and functionally, until near birth. We also generate a transcriptional atlas of perinatal BM HSPCs and the BM niche in mice across ontogeny, revealing that fetal BM lacks HSPCs with robust intrinsic stem cell programs, as well as niche cells supportive of HSPCs. In contrast, stem cell programs are preserved in neonatal BM HSPCs, which reside in a niche expressing HSC supportive factors distinct from those seen in adults. Collectively, our results provide important insights into the factors shaping hematopoiesis during this understudied window of hematopoietic development.
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Medula Óssea , Células-Tronco Hematopoéticas , Animais , Feminino , Feto , Hematopoese , Camundongos , Parto , GravidezRESUMO
Chimeric antigen receptor (CAR) T-cell therapy targeting T-cell acute lymphoblastic leukemia (T-ALL) faces limitations such as antigen selection and limited T-cell persistence. CD7 is an attractive antigen for targeting T-ALL, but overlapping expression on healthy T cells leads to fratricide of CD7-CAR T cells, requiring additional genetic modification. We took advantage of naturally occurring CD7- T cells to generate CD7-CAR (CD7-CARCD7-) T cells. CD7-CARCD7- T cells exhibited a predominantly CD4+ memory phenotype and had significant antitumor activity upon chronic antigen exposure in vitro and in xenograft mouse models. Based on these encouraging results, we next explored the utility of CD7- T cells for the immunotherapy of CD19+ hematological malignancies. Direct comparison of nonselected (bulk) CD19-CAR and CD19-CARCD7- T cells revealed that CD19-CARCD7- T cells had enhanced antitumor activity compared with their bulk counterparts in vitro and in vivo. Lastly, to gain insight into the behavior of CD19-CAR T cells with low levels of CD7 gene expression (CD7lo) in humans, we mined single-cell gene and T-cell receptor (TCR) expression data sets from our institutional CD19-CAR T-cell clinical study. CD19-CARCD7lo T cells were present in the initial CD19-CAR T-cell product and could be detected postinfusion. Intriguingly, the only functional CD4+ CD19-CAR T-cell cluster observed postinfusion exhibited CD7lo expression. Additionally, samples from patients responsive to therapy had a higher proportion of CD7lo T cells than nonresponders (NCT03573700). Thus, CARCD7- T cells have favorable biological characteristics and may present a promising T-cell subset for adoptive cell therapy of T-ALL and other hematological malignancies.
Assuntos
Neoplasias Hematológicas , Leucemia-Linfoma Linfoblástico de Células T Precursoras , Humanos , Camundongos , Animais , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Receptores de Antígenos de Linfócitos T , Imunoterapia Adotiva , Neoplasias Hematológicas/terapia , Imunoterapia , Antígenos CD19RESUMO
T cells expressing CD19-specific chimeric antigen receptors (CD19-CARs) have potent antileukemia activity in pediatric and adult patients with relapsed and/or refractory B-cell acute lymphoblastic leukemia (B-ALL). However, not all patients achieve a complete response (CR), and a significant percentage relapse after CD19-CAR T-cell therapy due to T-cell intrinsic and/or extrinsic mechanisms. Thus, there is a need to evaluate new CD19-CAR T-cell products in patients to improve efficacy. We developed a phase 1/2 clinical study to evaluate an institutional autologous CD19-CAR T-cell product in pediatric patients with relapsed/refractory B-ALL. Here we report the outcome of the phase 1 study participants (n = 12). Treatment was well tolerated, with a low incidence of both cytokine release syndrome (any grade, n = 6) and neurotoxicity (any grade, n = 3). Nine out of 12 patients (75%) achieved a minimal residual disease-negative CR in the bone marrow (BM). High disease burden (≥40% morphologic blasts) before CAR T-cell infusion correlated with increased side effects and lower response rate, but not with CD19-CAR T-cell expansion. After infusion, CD8+ CAR T cells had a proliferative advantage over CD4+ CAR T cells and at peak expansion, had an effector memory phenotype with evidence of antigen-driven differentiation. Patients that proceeded to allogeneic hematopoietic cell transplantation (AlloHCT) had sustained, durable responses. In summary, the initial evaluation of our institutional CD19-CAR T-cell product demonstrates safety and efficacy while highlighting the impact of pre-infusion disease burden on outcomes. This trial was registered at www.clinicaltrials.gov as #NCT03573700.
Assuntos
Linfoma de Burkitt , Linfoma de Células B , Leucemia-Linfoma Linfoblástico de Células Precursoras , Receptores de Antígenos Quiméricos , Humanos , Antígenos CD19 , Linfócitos T CD8-Positivos , Efeitos Psicossociais da Doença , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Linfócitos TRESUMO
Genomic characterization of pediatric patients with acute myeloid leukemia (AML) has led to the discovery of somatic mutations with prognostic implications. Although gene-expression profiling can differentiate subsets of pediatric AML, its clinical utility in risk stratification remains limited. Here, we evaluate gene expression, pathogenic somatic mutations, and outcome in a cohort of 435 pediatric patients with a spectrum of pediatric myeloid-related acute leukemias for biological subtype discovery. This analysis revealed 63 patients with varying immunophenotypes that span a T-lineage and myeloid continuum designated as acute myeloid/T-lymphoblastic leukemia (AMTL). Within AMTL, two patient subgroups distinguished by FLT3-ITD and PRC2 mutations have different outcomes, demonstrating the impact of mutational composition on survival. Across the cohort, variability in outcomes of patients within isomutational subsets is influenced by transcriptional identity and the presence of a stem cell-like gene-expression signature. Integration of gene expression and somatic mutations leads to improved risk stratification. SIGNIFICANCE: Immunophenotype and somatic mutations play a significant role in treatment approach and risk stratification of acute leukemia. We conducted an integrated genomic analysis of pediatric myeloid malignancies and found that a combination of genetic and transcriptional readouts was superior to immunophenotype and genomic mutations in identifying biological subtypes and predicting outcomes. This article is highlighted in the In This Issue feature, p. 549.
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Leucemia Mieloide Aguda , Criança , Perfilação da Expressão Gênica , Genômica , Humanos , Leucemia Mieloide Aguda/diagnóstico , Mutação/genética , PrognósticoRESUMO
Nonsense-mediated RNA decay (NMD) is recognized as an RNA surveillance pathway that targets aberrant mRNAs with premature translation termination codons (PTC) for degradation, however, its molecular mechanisms and roles in health and disease remain incompletely understood. In this study, we developed a novel reporter system to accurately measure NMD activity in individual cells. A genome-wide CRISPR-Cas9 knockout screen using this reporter system identified novel NMD-promoting factors, including multiple components of the SF3B complex and other U2 spliceosome factors. Interestingly, cells with mutations in the spliceosome genes SF3B1 and U2AF1, which are commonly found in myelodysplastic syndrome (MDS) and cancers, have overall attenuated NMD activity. Compared with wild-type (WT) cells, SF3B1- and U2AF1-mutant cells were more sensitive to NMD inhibition, a phenotype that is accompanied by elevated DNA replication obstruction, DNA damage, and chromosomal instability. Remarkably, the sensitivity of spliceosome mutant cells to NMD inhibition was rescued by overexpression of RNase H1, which removes R-loops in the genome. Together, these findings shed new light on the functional interplay between NMD and RNA splicing and suggest a novel synthetic lethal strategy for the treatment of MDS and cancers with spliceosome mutations. SIGNIFICANCE: This study has developed a novel NMD reporter system and identified a potential therapeutic approach of targeting the NMD pathway to treat cancer with spliceosome gene mutations.
Assuntos
Mutação , Síndromes Mielodisplásicas/metabolismo , Degradação do RNAm Mediada por Códon sem Sentido , Fosfoproteínas/genética , Fatores de Processamento de RNA/genética , Fator de Processamento U2AF/genética , Ciclo Celular , Linhagem Celular Tumoral , Instabilidade Cromossômica , Corantes Fluorescentes , Regulação da Expressão Gênica , Genes Reporter , Estudo de Associação Genômica Ampla , Humanos , Células K562 , Proteínas de Ligação a RNA , RNA-Seq , Ribonuclease H/metabolismo , SpliceossomosRESUMO
PURPOSE OF REVIEW: Mutations in components of the spliceosome are the most common acquired lesions in myelodysplastic syndromes (MDS) and are frequently identified in other myeloid malignancies with a high rate of progression to acute myeloid leukemia (AML) including chronic myelomonocytic leukemia and primary myelofibrosis. The only curative option for these disorders remains allogeneic stem-cell transplantation, which is associated with high morbidity and mortality in these patients. The purpose of this review is to highlight the recent therapeutic developments and strategies being pursued for clinical benefit in splicing factor mutant myeloid malignancies. RECENT FINDINGS: Cells harboring splicing factor mutations have increased aberrant splicing leading to R-loop formation and cell cycle stalling that create dependencies on Checkpoint kinase 1 (CHK1) activation and canonical splicing maintained by protein arginine methyltransferase activity. Both targeting of the spliceosome and targeting of the downstream consequences of splicing factor mutation expression show promise as selective strategies for the treatment of splicing factor-mutant myeloid malignancies. SUMMARY: An improved understanding of the therapeutic vulnerabilities in splicing factor-mutant MDS and AML has led to the development of clinical trials of small molecule inhibitors that target the spliceosome, ataxia telangectasia and Rad3 related (ATR)-CHK1 pathway, and methylation of splicing components.
Assuntos
Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Terapia de Alvo Molecular , Mutação , Síndromes Mielodisplásicas/tratamento farmacológico , Síndromes Mielodisplásicas/genética , Fatores de Processamento de RNA/antagonistas & inibidores , Fatores de Processamento de RNA/genética , Animais , Biomarcadores , Gerenciamento Clínico , Suscetibilidade a Doenças , Desenvolvimento de Medicamentos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Leucemia Mieloide Aguda/diagnóstico , Síndromes Mielodisplásicas/diagnóstico , Splicing de RNA , Fatores de Processamento de RNA/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Hematopoietic stem and progenitor cells (HSPCs) govern the daily expansion and turnover of billions of specialized blood cells. Given their clinical utility, much effort has been made toward understanding the dynamics of hematopoietic production from this pool of stem cells. An understanding of hematopoietic stem cell clonal dynamics during blood ontogeny could yield important insights into hematopoietic regulation, especially during aging and repeated exposure to hematopoietic stress-insults that may predispose individuals to the development of hematopoietic disease. Here, we review the current state of research regarding the clonal complexity of the hematopoietic system during embryogenesis, adulthood, and hematologic disease.
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Doenças Hematológicas/metabolismo , Hematopoese , Células-Tronco Hematopoéticas/metabolismo , Estresse Fisiológico , Adulto , Doenças Hematológicas/patologia , Células-Tronco Hematopoéticas/patologia , HumanosRESUMO
Major advances in our understanding of cancer pathogenesis and therapy have come from efforts to catalog genomic alterations in cancer. A growing number of large-scale genomic studies have uncovered mutations that drive cancer by perturbing cotranscriptional and post-transcriptional regulation of gene expression. These include alterations that affect each phase of RNA processing, including splicing, transport, editing, and decay of messenger RNA. The discovery of these events illuminates a number of novel therapeutic vulnerabilities generated by aberrant RNA processing in cancer, several of which have progressed to clinical development. SIGNIFICANCE: There is increased recognition that genetic alterations affecting RNA splicing and polyadenylation are common in cancer and may generate novel therapeutic opportunities. Such mutations may occur within an individual gene or in RNA processing factors themselves, thereby influencing splicing of many downstream target genes. This review discusses the biological impact of these mutations on tumorigenesis and the therapeutic approaches targeting cells bearing these mutations.
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Neoplasias/genética , Processamento Pós-Transcricional do RNA , RNA Mensageiro/química , RNA Mensageiro/genética , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias/tratamento farmacológico , Poliadenilação , Processamento Pós-Transcricional do RNA/efeitos dos fármacos , Splicing de RNARESUMO
Studies of allelic variation underlying genetic blood disorders have provided important insights into human hematopoiesis. Most often, the identified pathogenic mutations result in loss-of-function or missense changes. However, assessing the pathogenicity of noncoding variants can be challenging. Here, we characterize two unrelated patients with a distinct presentation of dyserythropoietic anemia and other impairments in hematopoiesis associated with an intronic mutation in GATA1 that is 24 nucleotides upstream of the canonical splice acceptor site. Functional studies demonstrate that this single-nucleotide alteration leads to reduced canonical splicing and increased use of an alternative splice acceptor site that causes a partial intron retention event. The resultant altered GATA1 contains a five-amino acid insertion at the C-terminus of the C-terminal zinc finger and has no observable activity. Collectively, our results demonstrate how altered splicing of GATA1, which reduces levels of the normal form of this master transcription factor, can result in distinct changes in human hematopoiesis.
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Processamento Alternativo/genética , Anemia Diseritropoética Congênita/genética , Fator de Transcrição GATA1/genética , Hematopoese/genética , Íntrons/genética , Mutação de Sentido Incorreto , Síndromes Mielodisplásicas/genética , Adulto , Criança , Éxons , Células HEK293 , Células-Tronco Hematopoéticas/metabolismo , Humanos , Masculino , Síndromes Mielodisplásicas/patologia , Sítios de Splice de RNA/genética , Transcrição Gênica/genética , TransfecçãoRESUMO
SF3B1 is recurrently mutated in chronic lymphocytic leukemia (CLL), but its role in the pathogenesis of CLL remains elusive. Here, we show that conditional expression of Sf3b1-K700E mutation in mouse B cells disrupts pre-mRNA splicing, alters cell development, and induces a state of cellular senescence. Combination with Atm deletion leads to the overcoming of cellular senescence and the development of CLL-like disease in elderly mice. These CLL-like cells show genome instability and dysregulation of multiple CLL-associated cellular processes, including deregulated B cell receptor signaling, which we also identified in human CLL cases. Notably, human CLLs harboring SF3B1 mutations exhibit altered response to BTK inhibition. Our murine model of CLL thus provides insights into human CLL disease mechanisms and treatment.