Newly diagnosed multiple myeloma with bleeding and coagulation abnormalities caused by a thrombin-inhibiting substance.

Approximately 7% of patients with newly diagnosed multiple myeloma (MM) experience bleeding complications with varying causes, but few reports have described these complications. Here we report the case of a patient with newly diagnosed MM who presented with a bleeding tendency and various coagulation abnormalities. Chromogenic assays, thrombin time, and reptilase time revealed the presence of a thrombin-inhibiting substance that inhibited release of fibrinopeptide A from fibrinogen. The coagulation abnormalities improved after treatment with daratumumab, lenalidomide, and dexamethasone. As the thrombin inhibition mechanism remains unclear, no previous studies have reported recent treatment outcomes in older patients producing thrombin-inhibiting substances, which can hinder clinical treatment. Therefore, we believe that the diagnosis and the treatment course of this case provide valuable information. Moreover, such case reports provide significant insights into the pathophysiology of bleeding complications associated with MM.

Recent advances in AML with mutated NPM1.

Nucleophosmin 1 (NPM1) mutation is one of the most prevalent genetic mutations in adult acute myeloid leukemia (AML) and is particularly predominant in AML with a normal karyotype. NPM1 is a chaperone protein that plays various roles in several cellular processes. Wild-type NPM1 is normally localized to the nucleus, whereas mutant NPM1 proteins exhibit altered cytoplasmic localization. Clinically, AML with mutated NPM1 without FLT3-ITD is associated with a higher complete remission rate and improved overall survival. AML with mutated NPM1 is categorized as a distinct genetic entity in the World Health Organization classification of hematopoietic malignancies due to its unique clinical and biological features. However, the precise roles of NPM1 in normal hematopoiesis and in AML development remain unclear. Recent studies have revealed various clinical applications of NPM1 mutations in AML treatment, particularly in measurable residual disease analyses that target mutant NPM1 transcripts and in potential therapeutic applications of menin inhibitors and XPO-1 inhibitors for AML with mutated NPM1. Thus, NPM1 mutation is highly significant in AML classification, prognosis, response assessment, and molecular targeted therapies. Here, we review recent progress in clinical and biological aspects of AML with mutated NPM1 including molecular targeted therapy.

Predictive significance of high neutrophil ratio for thrombosis in myeloproliferative neoplasms: JSH-MPN-R18 subanalysis.

Thrombosis in myeloproliferative neoplasms (MPNs) is an important clinical problem, and risk-stratified management is essential. To identify the clinical characteristics of thrombosis in patients with MPNs, a nationwide multi-institutional retrospective analysis (JSH-MPN-R18) was conducted. The aim of the present study was to perform a sub-analysis of JSH-MPN-R18 findings to clarify the predictive parameters for thrombosis among complete blood count (CBC) results. Among the patients enrolled in JSH-MPN-R18, those with essential thrombocythemia (ET; n = 1152) and polycythemia vera (PV; n = 456) were investigated. We analyzed and compared CBC parameters between patients with and those without any thrombotic events using Welch's T-test. Statistical analyses were performed using the R statistical software. Thrombotic events were observed in 74 patients with ET. In multivariate analysis, only the neutrophil ratio was slightly but significantly higher for ET patients with thrombosis than for those without (p < 0.05). Of note, the absolute neutrophil count (aNeu) was considered a useful predictive tool for thrombosis among patients classified as low-risk according to the revised International Prognostic Score of Thrombosis for Essential Thrombocythemia. Among PV patients, those with thrombosis showed significantly higher hematocrit and aNeu than did those without thrombosis. As a thrombosis-associated factor, the neutrophil ratio was slightly but significantly elevated in patients with ET. This myeloid skew might reflect a higher value of JAK2 V617F allelic frequency in patients with ET with thrombosis; this was not clarified in JSH-MPN-R18. Further accumulation of evidence, including genetic information for JAK2 and other passenger mutations, is warranted.

RGS1 and CREB5 are direct and common transcriptional targets of ZNF384-fusion proteins.

BACKGROUND: ZNF384-fusion (Z-fusion) genes were recently identified in B-cell acute lymphoblastic leukemia (B-ALL) and are frequent in Japanese adult patients. The frequency is about 20% in those with Philadelphia chromosome-negative B-ALL. ZNF384 is a transcription factor and Z-fusion proteins have increased transcriptional activity; however, the detailed mechanisms of leukemogenesis of Z-fusion proteins have yet to be clarified. METHODS: We established three transfectants of cell lines expressing different types of Z-fusion proteins, and analyzed their gene expression profile (GEP) by RNA-seq. We also analyzed the GEP of clinical ALL samples using our previous RNA-seq data of 323 Japanese ALL patients. We selected upregulated genes in both Z-fusion gene-expressing transfectants and Z-fusion gene-positive ALL samples, and investigated the binding of Z-fusion proteins to regulatory regions of the candidate genes by ChIP-qPCR. RESULTS: We selected six commonly upregulated genes. After the investigation by ChIP-qPCR, we finally identified CREB5 and RGS1 as direct and common target genes. RGS1 is an inhibitor of CXCL12-CXCR4 signaling that is required for the homing of hematopoietic progenitor cells to the bone marrow microenvironment and development of B cells. Consistent with this, Z-fusion gene transfectants showed impaired migration toward CXCL12. CONCLUSIONS: We identified CREB5 and RGS1 as direct and common transcriptional targets of Z-fusion proteins. The present results provide novel insight into the aberrant transcriptional regulation by Z-fusion proteins.

Nilotinib vs. Dasatinib in Achieving MR4.5 for de novo Chronic Myeloid Leukemia: the Randomized JALSG CML212 Study.

Treatment-free remission (TFR) is a new therapeutic goal for chronic myeloid leukemia in chronic phase (CML-CP). Deep molecular response (DMR) is a prerequite condition for TFR. The Japan Adult Leukemia Study Group (JALSG) conducted a multicentral prospective randomized phase 3 CML212 study for de novo CML-CP to compare the cumulative achievement of MR4.5 (international scale [IS] BCR::ABL1≤0.0032%) by 18 months between nilotinib and dasatinib as a primary endpoint. A total of 454 patients were randomly assigned to the nilotinib 300 mg, bid arm or dasatinib 100 mg, qd arm (both, n=227). BCR::ABL1 mRNA levels were monitored every three months. Study treatment was stopped if the patients were judged as failure by the European LekemiaNet (ELN) 2009 criteria or showed intolerance. The cumulative achievement rates of MR4.5 by 18 months were 32.6% (95% confidence interval [CI]: 26.5-39.1%) in the nilotinib arm and 30.8% (95% CI: 24.9-37.3%) in the dasatinib arm with no significant difference (p=0.66). Also, the cumulative achievement rates of early molecular response (EMR), complete cytogenetic response (CCyR) and major molecular response (MMR), MR4.0 by 12, 18, 24, and 36 months were almost the same between the two arms. At 36 months, 66.5% and 65.0% patients continued nilotinib and dasatinib, respectively (p=0.76). There was no significant difference in progression-free survival (PFS) or overall survival (OS) between the two arms by log-rank tests (PFS, p=0.58; OS, p=0.64). These results suggest that nilotinib and dasatinib would be equally effective for de novo CML-CP patients with similar continuity. UMIN Clinical Trials Registry (#UMIN000007909).

Clonal evolution process from essential thrombocythemia to acute myeloid leukemia in the original patient from whom the CALR-mutated Marimo cell line was established.

We previously reported the Marimo cell line, which was established from the bone marrow cells of a patient with essential thrombocythemia (ET) at the last stage after transformation to acute myeloid leukemia (AML). This cell line is widely used for the biological analysis of ET because it harbors CALR mutation. However, genetic processes during disease progression in the original patient were not analyzed. We sequentially analyzed the genetic status in the original patient samples during disease progression. The ET clone had already acquired CALR and MPL mutations, and TP53 and NRAS mutations affected the disease progression from ET to AML in this patient. Particularly, the variant allele frequency of the NRAS mutation increased along with the disease progression after transformation, and the NRAS-mutated clone selectively proliferated in vitro, resulting in the establishment of the Marimo cell line. Although CALR and MPL mutations co-existed, MPL was not expressed in Marimo cells or any clinical samples. Furthermore, mitogen-activated protein kinase (MAPK) but not the JAK2-STAT pathway was activated. These results collectively indicate that MAPK activation is mainly associated with the proliferation ability of Marimo cells.

Initiating-clone analysis in patients with acute myeloid leukemia secondary to essential thrombocythemia.

Most of essential thrombocythemia (ET) patients have the clone harboring a mutation in one of the JAK2, CALR, or MPL gene, and these clones generally acquire additional mutations at transformation to acute myeloid leukemia (AML). However, the proliferation of triple-negative clones has sometimes been observed at AML transformation. To clarify the clonal evolution of ET to AML, we analyzed paired samples at ET and AML transformation in eight patients. We identified that JAK2-unmutated AML clones proliferated at AML transformation in three patients in whom the JAK2-mutated clone was dominant at ET. In two patients, TET2-mutated, but not JAK2-mutated, clones might be common initiating clones for ET and transformed AML. In a patient with JAK2-mutated ET, SMARCC2, UBR4, and ZNF143, but not JAK2, -mutated clones proliferated at AML transformation. Precise analysis using single-cell sorted CD34+/CD38- fractions suggested that ET clone with JAK2-mutated and AML clone with TP53 mutation was derived from the common clone with these mutations. Although further study is required to clarify the biological significance of SMARCC2, UBR4, and ZNF143 mutations during disease progression of ET and AML transformation, the present results demonstrate the possibility of a common initial clone involved in both ET and transformed AML.

NUP98-BPTF promotes oncogenic transformation through PIM1 upregulation.

INTRODUCTION: Nucleoporin 98 (NUP98) fusion proteins are recurrently found in leukemia and are associated with unfavorable clinical outcomes. They are distributed to the nucleus and contribute to leukemogenesis via aberrant transcriptional regulation. We previously identified NUP98-BPTF (NB) fusion in patients with T-cell acute lymphoblastic leukemia (T-ALL) using next-generation sequencing. The FG-repeat of NUP98 and the PHD finger and bromodomain of bromodomain PHD finger transcription factor (BPTF) are retained in the fusion. Like other NUP98 fusion proteins, NB is considered to regulate genes that are essential for leukemogenesis. However, its target genes or pathways remain unknown. MATERIALS AND METHODS: To investigate the potential oncogenic properties of the NB fusion protein, we lentivirally transduced a doxycycline-inducible NB expression vector into mouse NIH3T3 fibroblasts and human Jurkat T-ALL cells. RESULTS: NB promoted the transformation of mouse NIH3T3 fibroblasts by upregulating the proto-oncogene Pim1, which encodes a serine/threonine kinase. NB transcriptionally regulated Pim1 expression by binding to its promoter and activated MYC and mTORC1 signaling. PIM1 knockdown or pharmacological inhibition of mTORC1 signaling suppressed NB-induced NIH3T3 cell transformation. Furthermore, NB enhanced the survival of human Jurkat T-ALL cells by inactivating the pro-apoptotic protein BCL2-associated agonist of cell death (BAD). CONCLUSION: We demonstrated the pivotal role of NB in cell transformation and survival and identified PIM1as a key downstream target of NB. These findings propose a promising therapeutic strategy for patients with NB fusion-positive leukemia.

Human iPSC-derived CD4+ Treg-like cells engineered with chimeric antigen receptors control GvHD in a xenograft model.

CD4+ T cells induced from human iPSCs (iCD4+ T cells) offer a therapeutic opportunity for overcoming immune pathologies arising from hematopoietic stem cell transplantation. However, most iCD4+ T cells are conventional helper T cells, which secrete inflammatory cytokines. We induced high-level expression of FOXP3, a master transcription factor of regulatory T cells, in iCD4+ T cells. Human iPSC-derived, FOXP3-induced CD4+ T (iCD4+ Treg-like) cells did not secrete inflammatory cytokines upon activation. Moreover, they showed demethylation of the Treg-specific demethylation region, suggesting successful conversion to immunosuppressive iCD4+ Treg-like cells. We further assessed these iCD4+ Treg-like cells for CAR-mediated immunosuppressive ability. HLA-A2 CAR-transduced iCD4+ Treg-like cells inhibited CD8+ cytotoxic T cell (CTL) division in a mixed lymphocyte reaction assay with A2+ allogeneic CTLs and suppressed xenogeneic graft-versus-host disease (GVHD) in NSG mice treated with A2+ human PBMCs. In most cases, these cells suppressed the xenogeneic GvHD progression as much as natural CD25+CD127- Tregs did.

Phase II study in children and adults under 40 years with newly diagnosed Langerhans cell histiocytosis: protocol for an LCH-19-MSMFB clinical trial in Japan.

INTRODUCTION: Although the prognosis of Langerhans cell histiocytosis (LCH) is excellent, the high recurrence rate and permanent consequences, such as central diabetes insipidus and LCH-associated neurodegenerative diseases, remain to be resolved. Based on previous reports that patients with high-risk multisystem LCH show elevated levels of inflammatory molecules, we hypothesised that dexamethasone would more effectively suppress LCH-associated inflammation, especially in the central nervous system (CNS). We further hypothesised that intrathecal chemotherapy would effectively reduce CNS complications. We administer zoledronate to patients with multifocal bone LCH based on an efficacy report from a small case series. METHODS AND ANALYSIS: This phase II study (labelled the LCH-19-MSMFB study) is designed to evaluate the significance of introducing dexamethasone and intrathecal chemotherapy for multisystem disease and zoledronate for multifocal bone disease in previously untreated, newly diagnosed children, adolescents (under 20 years) and adults under 40 years. The primary endpoint is the 3-year event-free survival rate by risk group of under 20 years and the 3-year event-free survival rate of 20 years and over. ETHICS AND DISSEMINATION: This study was approved by the Central Review Board of the National Hospital Organisation Nagoya Medical Centre (Nagoya, Japan) on 21 January 2022 and was registered in the Japan Registry of Clinical Trials (https://jrct.niph.go.jp/en-latest-detail/jRCTs041210027). Written informed consent will be obtained from all patients and/or their guardians. TRIAL REGISTRATION NUMBER: jRCTs041210027.

A phase 1/2 study of NS-87/CPX-351 (cytarabine and daunorubicin liposome) in Japanese patients with high-risk acute myeloid leukemia.

OBJECTIVES: NS-87/CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin. NS-87/CPX-351 exerts antileukemic action by maintaining a synergistic molar ratio of cytarabine to daunorubicin of 5:1 within the liposome while in circulation. Patients with high-risk acute myeloid leukemia (AML), which includes therapy-related AML and AML with myelodysplasia-related changes (AML-MRC), have poorer outcomes than those with other AML. METHODOLOGY: This open-label phase 1/2 (P1/2) study was conducted in 47 Japanese patients aged 60-75 years with newly diagnosed high-risk AML to evaluate the pharmacokinetics, safety, and efficacy of NS-87/CPX-351. RESULTS: In the 6 patients enrolled in the P1 portion, no dose-limiting toxicities (DLTs) were reported, and 100 units/m2 during the induction cycle was found to be acceptable. Cytarabine and daunorubicin had a long half-life in the terminal phase (32.8 and 28.7 h, respectively). In the 35 patients enrolled in the P2 portion, composite complete remission (CRc; defined as complete remission [CR] or CR with incomplete hematologic recovery [CRi]) was achieved in 60.0% (90% CI: 44.7-74.0) of the patients. Adverse events due to NS-87/CPX-351 were well tolerated. OUTCOMES: NS-87/CPX-351 can be considered as a frontline treatment option for Japanese patients with high-risk AML.

Utility of allogeneic stem cell transplantation for adult Ph+ALL with complete molecular remission.

This study aimed to investigate the usefulness of allogeneic stem cell transplantation (allo-SCT) for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) in the first complete remission (CR1) with complete molecular remission (CMR). We compared the outcomes between Ph+ALL patients who did or did not undergo allo-SCT in CR1. We included patients enrolled in the prospective clinical studies in the tyrosine kinase inhibitor era conducted by the Japan Adult Leukemia Study Group, who achieved CMR within 3 months. A total of 147 patients (allo-SCT: 101; non-SCT: 46) were eligible for this analysis. In the multivariate analyses, allo-SCT was significantly associated with both superior overall survival (OS) (adjusted hazard ratio (aHR): 0.54; 95% CI: 0.30-0.97; p = .04) and relapse-free survival (RFS) (aHR: 0.21; 95% CI: 0.12-0.38; p < .001). The 5-year adjusted OS and RFS were 73% and 70% in the allo-SCT cohort, whereas they were 50% and 20% in the non-SCT cohort. Despite the higher non-relapse mortality (aHR: 3.49; 95% CI: 1.17-10.4; p = .03), allo-SCT was significantly associated with a lower relapse rate (aHR: 0.10; 95% CI: 0.05-0.20; p < .001). In addition, allo-SCT was also associated with superior graft-versus-host disease-free, relapse-free survival (aHR: 0.43; 95% CI: 0.25-0.74; p = .002). Propensity score-matched analyses confirmed the results of the multivariate analyses. In patients who achieved CMR within 3 months, allo-SCT in CR1 had superior survival and lower relapse compared with the non-SCT cohort.

Epstein-Barr virus lytic gene BNRF1 promotes B-cell lymphomagenesis via IFI27 upregulation.

Epstein-Barr virus (EBV) is a ubiquitous human lymphotropic herpesvirus that is causally associated with several malignancies. In addition to latent factors, lytic replication contributes to cancer development. In this study, we examined whether the lytic gene BNRF1, which is conserved among gamma-herpesviruses, has an important role in lymphomagenesis. We found that lymphoblastoid cell lines (LCLs) established by BNRF1-knockout EBV exhibited remarkably lower pathogenicity in a mice xenograft model than LCLs produced by wild-type EBV (LCLs-WT). RNA-seq analyses revealed that BNRF1 elicited the expression of interferon-inducible protein 27 (IFI27), which promotes cell proliferation. IFI27 knockdown in LCLs-WT resulted in excessive production of reactive oxygen species, leading to cell death and significantly decreased their pathogenicity in vivo. We also confirmed that IFI27 was upregulated during primary infection in B-cells. Our findings revealed that BNRF1 promoted robust proliferation of the B-cells that were transformed by EBV latent infection via IFI27 upregulation both in vitro and in vivo.

Dual CAR-T Cells Targeting CD19 and CD37 Are Effective in Target Antigen Loss B-cell Tumor Models.

Chimeric antigen receptor T (CAR-T) cells targeting multiple antigens (Ag), may reduce the risk of immune escape following the loss of the target Ag and further increase the efficacy of treatment. We developed dual-targeting CAR-T cells that target CD19 and CD37 Ags and evaluated their antitumor effects. CD19/CD37 dual CAR-T cells were generated using cotransduction and simultaneous gene transfer of two types of lentiviral vectors transferring CD19CAR or CD37CAR genes, including the intracellular domains of CD28 and CD3ζ signaling domains. These dual CAR-T cells contained three fractions: CD19/CD37 bispecific CAR-T cells, single CD19CAR-T cells, and single CD37CAR-T cells. In the functional evaluation of CAR-T cells in vitro, CD19/CD37 dual CAR-T cells showed adequate proliferation and cytokine production in response to CD19 and CD37 antigen stimulation alone or in combination. Evaluation of intracellular signaling revealed that dual CAR-T cell-mediated signals were comparable with single CAR-T cells in response to CD19- and CD37-positive B-cell tumors. Although the cytotoxicity of CD19/CD37 dual CAR-T cells in both CD19- and CD37-positive B-cell tumors was similar to that of single CD19 and CD37CAR-T cells, against CD19 and CD37 Ag-heterogeneous tumor, dual CAR-T cells demonstrated significantly superior tumor lysis compared with single CAR-T cells. Furthermore, CD19/CD37 dual CAR-T cells effectively suppressed Ag-heterogeneous Raji cells in a xenograft mouse model. Collectively, these results suggest that CD19/CD37 dual CAR-T cells may be effective target-Ag-loss B-cell tumor models in vitro and in vivo, which represents a promising treatment for patients with relapsed/refractory B-cell malignancies.

Real-world data of MDS and CMML in Japan: results of JALSG clinical observational study-11 (JALSG-CS-11).

We conducted a multicenter, prospective observational study of acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and chronic myelomonocytic leukemia (CMML) in Japan. From August 2011 to January 2016, we enrolled 6568 patients. Herein, we report the results for MDS (n = 2747) and CMML (n = 182). The percentage of patients aged 65 years or older was 79.5% for MDS and 79.7% for CMML. The estimated overall survival (OS) rate and cumulative incidence of AML evolution at 5 years were 32.3% (95% confidence interval: 30.2-34.5%) and 25.7% (23.9-27.6%) for MDS, and 15.0% (8.9-22.7%) and 39.4% (31.1-47.6%) for CMML. Both diseases were more common in men. The most common treatment for MDS was azacitidine, which was used in 45.4% of higher-risk and 12.7% of lower-risk MDS patients. The 5-year OS rate after treatment with azacitidine was 12.1% (9.5-15.1%) for of higher-risk MDS patients and 33.9% (25.6-42.4%) for lower-risk patients. The second most common treatment was erythropoiesis-stimulating agents, given to just 20% of lower-risk patients. This is the first paper presenting large-scale, Japanese data on survival and clinical characteristics in patients with MDS and CMML.

Real-world data of AML in Japan: results of JALSG clinical observational study-11 (JALSG-CS-11).

This report covers acute myeloid leukemia (AML) results from a multicenter, prospective observational study of AML, myelodysplastic syndromes, and chronic myelomonocytic leukemia in Japan. From August 2011 to January 2016, 3728 AML patients were registered. Among them, 42% were younger than 65, and the male-to-female ratio was 1.57:1. With a median follow-up time of 1807 days (95% confidence interval [CI]: 1732-1844 days), the estimated 5-year overall survival (OS) rate in AML patients (n = 3707) was 31.1% (95% CI: 29.5-32.8%). Trial-enrolled patients had a 1.7-fold higher OS rate than non-enrolled patients (5-year OS, 58.9% [95% CI: 54.5-63.1%] vs 35.5% [33.3-37.8%], p < 0.0001). Women had a higher OS rate than men (5-year OS, 34% [95% CI; 31.4-36.7%] vs 27.7% [25.7-29.7%], p < 0.0001). The OS rate was lower in patients aged 40 and older than those under 40, and even lower in those over 65 (5-year OS for ages < 40, 40-64, 65-74, ≥ 75: 74.5% [95% CI; 69.3-79.0%] vs 47.5% [44.4-50.6%] vs 19.3% [16.8-22.0%] vs 7.3% [5.5-9.4%], respectively). This is the first paper to present large-scale data on survival and clinical characteristics in Japanese AML patients.

Outcomes of transplant-eligible patients with myelodysplastic syndrome with excess blasts registered in an observational study: The JALSG-CS11-MDS-SCT.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the sole curative therapy for myelodysplastic syndrome (MDS). However, whether bridging therapy (BRT) including azacitidine (AZA) and combination chemotherapy (CCT) prior to allo-SCT should be performed is unclear. We analyzed BRT and the outcomes of patients with myelodysplastic syndrome with excess blasts (MDS-EB) who were ≤ 70 years old at the time of registration for a prospective observational study to clarify the optimal allo-SCT strategy for high-risk MDS. A total of 371 patients were included in this study. Among 188 patients (50.7%) who were considered for allo-SCT, 141 underwent allo-SCT. Among the patients who underwent allo-SCT, 64 received AZA, 29 received CCT, and 26 underwent allo-SCT without BRT as the initial treatment. Multivariate analysis identified BRT as an independent factor influencing overall survival (AZA vs. without BRT, hazard ratio [HR] 3.33, P = 0.005; CCT vs. without BRT, HR 3.82, P = 0.003). In multivariate analysis, BRT was independently associated with progression-free survival (AZA vs. without BRT: HR, 2.23; P = 0.041; CCT vs. without BRT: HR, 2.94; P = 0.010). Transplant-eligible patients with MDS-EB should undergo allo-SCT when clinically acceptable, and upfront allo-SCT without BRT may be superior to AZA or CCT.

Clonal hematopoiesis of a novel dic(18;20) clone following allogeneic hematopoietic stem cell transplantation.

A 55-year-old man in first complete remission of acute myeloid leukemia with a normal karyotype underwent allogeneic hematopoietic stem cell transplantation from a human-leukocyte-antigen-matched sibling. Bone marrow examination on day 28 confirmed complete remission, but G-banding analysis revealed a novel chromosomal abnormality, including dic(18;20)(p11.2;q11.2). The patient developed moderate chronic graft-versus-host disease on day 174, and the abnormal clones identified by dic(18;20) significantly increased after that point. Chimerism testing repeatedly confirmed complete donor type. Although next-generation sequencing showed no clonal hematopoiesis-related gene mutations, copy number analysis of the donor and the recipient revealed copy number deletion of 18p, 18q, and 20q. The patient has maintained remission for more than 2 years to date without developing a hematologic neoplasm or cytopenia. The distinctive clonal hematopoiesis with a dicentric chromosome seemed to have undergone the breakage-fusion-bridge cycle, which could cause the complex events of deletion, amplification, and inversion. These copy number alterations might have increased the number of clones with growth advantage, and the highly inflammatory environment in the recipient due to graft-versus-host disease might have contributed to the clonal selection.

Suppression of super-enhancer-driven TAL1 expression by KLF4 in T-cell acute lymphoblastic leukemia.

TAL1 is one of the most frequently dysregulated genes in T-ALL and is overexpressed in about 50% of T-ALL cases. One of the molecular mechanisms of TAL1 overexpression is abnormal mutations in the upstream region of the TAL1 promoter that introduce binding motifs for the MYB transcription factor. MYB binding at this location creates a 5' TAL1 super-enhancer (SE), which leads to aberrant expression of TAL1 and is associated with unfavorable clinical outcomes. Although targeting TAL1 is considered to be an attractive therapeutic strategy for patients with T-ALL, direct inhibition of transcription factors is challenging. Here, we show that KLF4, a known tumor suppressor in leukemic cells, suppresses SE-driven TAL1 expression in T-ALL cells. Mechanistically, KLF4 downregulates MYB expression by directly binding to its promoter and inhibits the formation of 5' TAL1 SE. In addition, we found that APTO-253, a small molecule inducer of KLF4, exerts an anti-leukemic effect by targeting SE-driven TAL1 expression in T-ALL cells. Taken together, our results suggest that the induction of KLF4 is a promising strategy to control TAL1 expression and could be a novel treatment for T-ALL patients with a poor prognosis.