Investigation of inherited noncoding genetic variation impacting the pharmacogenomics of childhood acute lymphoblastic leukemia treatment.

Defining genetic factors impacting chemotherapy failure can help to better predict response and identify drug resistance mechanisms. However, there is limited understanding of the contribution of inherited noncoding genetic variation on inter-individual differences in chemotherapy response in childhood acute lymphoblastic leukemia (ALL). Here we map inherited noncoding variants associated with treatment outcome and/or chemotherapeutic drug resistance to ALL cis-regulatory elements and investigate their gene regulatory potential and target gene connectivity using massively parallel reporter assays and three-dimensional chromatin looping assays, respectively. We identify 54 variants with transcriptional effects and high-confidence gene connectivity. Additionally, functional interrogation of the top variant, rs1247117, reveals changes in chromatin accessibility, PU.1 binding affinity and gene expression, and deletion of the genomic interval containing rs1247117 sensitizes cells to vincristine. Together, these data demonstrate that noncoding regulatory variants associated with diverse pharmacological traits harbor significant effects on allele-specific transcriptional activity and impact sensitivity to antileukemic agents.

miR-133a and miR-135a Regulate All-Trans Retinoic Acid-Mediated Differentiation in Pediatric Acute Myeloid Leukemia by Inhibiting CDX2 Translation and Serve as Prognostic Biomarkers.

Background: Acute myeloid leukemia (AML) is a type of blood cancer characterized by excessive growth of immature myeloid cells. Unfortunately, the prognosis of pediatric AML remains unfavorable. It is imperative to further our understanding of the mechanisms underlying leukemogenesis and explore innovative therapeutic approaches to enhance overall disease outcomes for patients with this condition. Methods: Quantitative reverse-transcription PCR was used to quantify the expression levels of microRNA (miR)-133a and miR-135a in 68 samples from 59 pediatric patients with AML. Dual-luciferase reporter transfection assay, Cell Counting Kit-8 assay, and western blot analysis were used to investigate the functions of miR-133a and miR-135a. Results: Our study found that all-trans-retinoic acid (ATRA) promoted the expression of miR-133a and miR-135a in AML cells, inhibited caudal type homeobox 2 (CDX2) expression, and subsequently inhibited the proliferation of AML cells. Additionally, miR-133a and miR-135a were highly expressed in patients with complete remission and those with better survival. Conclusions: miR-133a and miR-135a may play an antioncogenic role in pediatric AML through the ATRA-miRNA133a/135a-CDX2 pathway. They hold promise as potentially favorable prognostic indicators and novel therapeutic targets for pediatric AML.

Systems Biology for Drug Target Discovery in Acute Myeloid Leukemia.

Combining new therapeutics with all-trans-retinoic acid (ATRA) could improve the efficiency of acute myeloid leukemia (AML) treatment. Modeling the process of ATRA-induced differentiation based on the transcriptomic profile of leukemic cells resulted in the identification of key targets that can be used to increase the therapeutic effect of ATRA. The genome-scale transcriptome analysis revealed the early molecular response to the ATRA treatment of HL-60 cells. In this study, we performed the transcriptomic profiling of HL-60, NB4, and K562 cells exposed to ATRA for 3-72 h. After treatment with ATRA for 3, 12, 24, and 72 h, we found 222, 391, 359, and 1032 differentially expressed genes (DEGs) in HL-60 cells, as well as 641, 1037, 1011, and 1499 DEGs in NB4 cells. We also found 538 and 119 DEGs in K562 cells treated with ATRA for 24 h and 72 h, respectively. Based on experimental transcriptomic data, we performed hierarchical modeling and determined cyclin-dependent kinase 6 (CDK6), tumor necrosis factor alpha (TNF-alpha), and transcriptional repressor CUX1 as the key regulators of the molecular response to the ATRA treatment in HL-60, NB4, and K562 cell lines, respectively. Mapping the data of TMT-based mass-spectrometric profiling on the modeling schemes, we determined CDK6 expression at the proteome level and its down-regulation at the transcriptome and proteome levels in cells treated with ATRA for 72 h. The combination of therapy with a CDK6 inhibitor (palbociclib) and ATRA (tretinoin) could be an alternative approach for the treatment of acute myeloid leukemia (AML).

CRKL but not CRKII contributes to hemin-induced erythroid differentiation of CML.

Destruction of erythropoiesis process leads to various diseases, including thrombocytopenia, anaemia, and leukaemia. miR-429-CT10 regulation of kinase-like (CRKL) axis involved in development, progression and metastasis of cancers. However, the exact role of miR-429-CRKL axis in leukaemic cell differentiation are still unknown. The current work aimed to uncover the effect of miR-429-CRKL axis on erythropoiesis. In the present study, CRKL upregulation was negatively correlated with miR-429 downregulation in both chronic myeloid leukaemia (CML) patient and CR patient samples. Moreover, CRKL expression level was significantly decreased while miR-429 expression level was increased during the erythroid differentiation of K562 cells following hemin treatment. Functional investigations revealed that overexpression and knockdown of CRKL was remarkably effective in suppressing and promoting hemin-induced erythroid differentiation of K562 cells, whereas, miR-429 exhibited opposite effects to CRKL. Mechanistically, miR-429 regulates erythroid differentiation of K562 cells by downregulating CRKL via selectively targeting CRKL-3'-untranslated region (UTR) through Raf/MEK/ERK pathway. Conversely, CRKII had no effect on erythroid differentiation of K562 cells. Taken together, our data demonstrated that CRKL (but not CRKII) and miR-429 contribute to development, progression and erythropoiesis of CML, miR-429-CRKL axis regulates erythropoiesis of K562 cells via Raf/MEK/ERK pathway, providing novel insights into effective diagnosis and therapy for CML patients.

The role of microRNAs in the development, progression and drug resistance of chronic myeloid leukemia and their potential clinical significance.

Chronic myeloid leukemia (CML) is a cancer of the bone marrow characterized by an uncontrolled increase in the production of myeloid cells. MicroRNAs (miRNAs) are a group of non-coding RNA molecules with a length of 19 to 25 nucleotides that participate in the regulation of gene expression after transcription. They also play an important role in many physiological processes, such as proliferation, differentiation, apoptosis, and hematopoiesis. The alterations in miRNA expression are associated with malignancies, including CML, which act as either oncogenes or tumor suppressors. MiRNA is secreted by cells and is found in body fluids such as blood, serum, and plasma. Alterations in miRNA levels can distinguish CML patients from healthy individuals. In this review, we summarize the roles of several miRNAs and their target genes in the development, progression, and drug resistance of CML as well as the effects of treatment on the expression of these miRNAs. Further, we discuss the potential role of miRNAs in the diagnosis, prognosis, and treatment response of CML.

SIRT2 regulates proliferation and chemotherapy response of MLL-ENL-driven acute myeloid leukemia.

Both MLL-AF9 and MLL-ENL leukemia fusion proteins drive oncogenic transformation of hematopoietic cells through their N-terminal DNA/histone binding mixed-lineage leukemia 1 domain and C-terminal fragment of AF9 or ENL containing an unstructured linker region and the ANC1 homology domain, which recruits transcription factors. Despite of their structural similarity, acute myeloid leukemia (AML) patients bearing MLL-ENL show more adverse outcomes compared to those with MLL-AF9. We recapitulated the clinical patterns of these two MLL-fusions driven AMLs using murine models and found that MLL-ENL AML cells showed slower cell cycle progression and more resistance to standard chemotherapy than MLL-AF9 cells. These phenotypes were primarily controlled by the linker regions of ENL and a highly conserved lysine residue K469 within. Substitution of K469 with an acetylated mimic glutamine abolished the ability of MLL-ENL to suppress proliferation and promote chemo-resistance. We showed that deacetylase Sirt2 might act as an upstream regulator of MLL-ENL. Deletion of Sirt2 promoted proliferation of AML cells with either MLL fusions. Importantly, loss of Sirt2 greatly enhanced the sensitivity of the MLL-ENL AML cells to chemo-treatment. Taken together, our study uncovered a unique regulatory role of Sirt2 in leukemogenesis and suggested targeting SIRT2 as a new way to sensitize MLL-ENL AML patience for chemotherapy.

CAR T cells redirected to cell surface GRP78 display robust anti-acute myeloid leukemia activity and do not target hematopoietic progenitor cells.

Developing CAR T cells for acute myeloid leukemia (AML) has been hampered by a paucity of targets that are expressed on AML blasts and not on hematopoietic progenitor cells (HPCs). Here we demonstrate that GRP78 is expressed on the cell surface of primary AML blasts but not HPCs. To target GRP78, we generate T cell expressing a GRP78-specific peptide-based CAR, which show evidence of minimal fratricide post activation/transduction and antigen-dependent T cell differentiation. GRP78-CAR T cells recognize and kill GRP78-positive AML cells without toxicity to HPCs. In vivo, GRP78-CAR T cells have significant anti-AML activity. To prevent antigen-dependent T cell differentiation, we block CAR signaling and GRP78 cell surface expression post activation by using dasatinib during GRP78-CAR T cell manufacturing. This significantly improves their effector function in vitro and in vivo. Thus, targeting cell surface GRP78-positive AML with CAR T cells is feasible, and warrants further active exploration.

Effective Menin inhibitor-based combinations against AML with MLL rearrangement or NPM1 mutation (NPM1c).

Treatment with Menin inhibitor (MI) disrupts the interaction between Menin and MLL1 or MLL1-fusion protein (FP), inhibits HOXA9/MEIS1, induces differentiation and loss of survival of AML harboring MLL1 re-arrangement (r) and FP, or expressing mutant (mt)-NPM1. Following MI treatment, although clinical responses are common, the majority of patients with AML with MLL1-r or mt-NPM1 succumb to their disease. Pre-clinical studies presented here demonstrate that genetic knockout or degradation of Menin or treatment with the MI SNDX-50469 reduces MLL1/MLL1-FP targets, associated with MI-induced differentiation and loss of viability. MI treatment also attenuates BCL2 and CDK6 levels. Co-treatment with SNDX-50469 and BCL2 inhibitor (venetoclax), or CDK6 inhibitor (abemaciclib) induces synergistic lethality in cell lines and patient-derived AML cells harboring MLL1-r or mtNPM1. Combined therapy with SNDX-5613 and venetoclax exerts superior in vivo efficacy in a cell line or PD AML cell xenografts harboring MLL1-r or mt-NPM1. Synergy with the MI-based combinations is preserved against MLL1-r AML cells expressing FLT3 mutation, also CRISPR-edited to introduce mtTP53. These findings highlight the promise of clinically testing these MI-based combinations against AML harboring MLL1-r or mtNPM1.

Dual targeting of the DNA damage response pathway and BCL-2 in diffuse large B-cell lymphoma.

Standard chemotherapies for diffuse large B-cell lymphoma (DLBCL), based on the induction of exogenous DNA damage and oxidative stress, are often less effective in the presence of increased MYC and BCL-2 levels, especially in the case of double hit (DH) lymphomas harboring rearrangements of the MYC and BCL-2 oncogenes, which enrich for a patient's population characterized by refractoriness to anthracycline-based chemotherapy. Here we hypothesized that adaptive mechanisms to MYC-induced replicative and oxidative stress, consisting in DNA damage response (DDR) activation and BCL-2 overexpression, could represent the biologic basis of the poor prognosis and chemoresistance observed in MYC/BCL-2-positive lymphoma. We first integrated targeted gene expression profiling (T-GEP), fluorescence in situ hybridization (FISH) analysis, and characterization of replicative and oxidative stress biomarkers in two independent DLBCL cohorts. The presence of oxidative DNA damage biomarkers identified a poor prognosis double expresser (DE)-DLBCL subset, characterized by relatively higher BCL-2 gene expression levels and enrichment for DH lymphomas. Based on these findings, we tested therapeutic strategies based on combined DDR and BCL-2 inhibition, confirming efficacy and synergistic interactions in in vitro and in vivo DH-DLBCL models. These data provide the rationale for precision-therapy strategies based on combined DDR and BCL-2 inhibition in DH or DE-DLBCL.

Targeting RIOK2 ATPase activity leads to decreased protein synthesis and cell death in acute myeloid leukemia.

Novel therapies for the treatment of acute myeloid leukemia (AML) are urgently needed, because current treatments do not cure most patients with AML. We report a domain-focused, kinome-wide CRISPR-Cas9 screening that identified protein kinase targets for the treatment of AML, which led to the identification of Rio-kinase 2 (RIOK2) as a potential novel target. Loss of RIOK2 led to a decrease in protein synthesis and to ribosomal instability followed by apoptosis in leukemic cells, but not in fibroblasts. Moreover, the ATPase function of RIOK2 was necessary for cell survival. When a small-molecule inhibitor was used, pharmacological inhibition of RIOK2 similarly led to loss of protein synthesis and apoptosis and affected leukemic cell growth in vivo. Our results provide proof of concept for targeting RIOK2 as a potential treatment of patients with AML.

Targeting leukemia-specific dependence on the de novo purine synthesis pathway.

Acute myeloid leukemia (AML) is a devastating disease, and clinical outcomes are still far from satisfactory. Here, to identify novel targets for AML therapy, we performed a genome-wide CRISPR/Cas9 screen using AML cell lines, followed by a second screen in vivo. We show that PAICS, an enzyme involved in de novo purine biosynthesis, is a potential target for AML therapy. AML cells expressing shRNA-PAICS exhibited a proliferative disadvantage, indicating a toxic effect of shRNA-PAICS. Treatment of human AML cells with a PAICS inhibitor suppressed their proliferation by inhibiting DNA synthesis and promoting apoptosis and had anti-leukemic effects in AML PDX models. Furthermore, CRISPR/Cas9 screens using AML cells in the presence of the inhibitor revealed genes mediating resistance or synthetic lethal to PAICS inhibition. Our findings identify PAICS as a novel therapeutic target for AML and further define components of de novo purine synthesis pathway and its downstream effectors essential for AML cell survival.

Comparison of 3-month cytogenetic and molecular assays for early assessment of long-term clinical impact after BCR-ABL1 tyrosine kinase inhibitor treatment in chronic myeloid leukemia.

To compare the clinical significance of 3-month cytogenetic and molecular monitoring, we analyzed 1,410 paired cytogenetic and molecular data from 705 chronic-phase chronic myeloid leukemia patients. Based on early cytogenetic response (ECyR, Ph+≤35 %) and molecular response (EMR, BCR-ABL1IS≤10 %) at 3 months, the patients were divided into four groups (group 1: ECyR + EMR, n = 560; group 2: no ECyR + EMR, n = 27; group 3: ECyR + no EMR, n = 55; group 4: no ECyR + no EMR, n = 63). By 10 years, major molecular response (MMR), deep molecular response (MR4.5), overall survival (OS), and progression-free survival (PFS) rates were significantly high in group 1 (P < 0.001). Comparing groups 2 and 3, the MMR (P = 0.096), MR4.5 (P = 0.945), OS (P = 0.832), and PFS (P = 0.627) rates tended to be higher in group 2, although not significantly. Thus, the cytogenetic assay can not only be useful but its addition may also provide a more precise prediction of MR4.5.

CN470 is a BET/CBP/p300 multi-bromodomain inhibitor and has an anti-tumor activity against MLL-rearranged acute lymphoblastic leukemia.

Acute lymphoblastic leukemia with chromosomal rearrangements involving the mixed-lineage leukemia (MLL) gene (MLL-r ALL) remains an incurable disease. Thus, development of a safe and effective therapeutic agent to treat this disease is crucial to address this unmet medical need. BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, and cyclic AMP response element binding protein binding protein (CBP) and p300, two paralogous histone acetyltransferases, are all considered cancer drug targets and simultaneous targeting of these proteins may have therapeutic advantages. Here, we demonstrate that a BET/CBP/p300 multi-bromodomain inhibitor, CN470, has anti-tumor activity against MLL-r ALL in vitro and in vivo. CN470, potently inhibited ligand binding to the bromodomains of BRD4, CBP, and p300 and suppressed the growth of MLL-r ALL cell lines and patient-derived cells with MLL rearrangements. CN470 suppressed mRNA and protein expression of MYC and induced apoptosis in MLL-r ALL cells, following a cell cycle arrest in the G1 phase. Moreover, CN470 reduced BRD4 binding to acetylated histone H3. The in vivo effects of CN470 were investigated using SEMLuc/GFP cells expressing luminescent markers in an orthotopic mouse model. Mice administered CN470 daily had prolonged survival compared to the vehicle group. Further, CN470 also showed anti-tumor effects against an MLL-r ALL patient-derived xenograft model. These findings suggest that inhibition of BET/CBP/p300 by the multi-bromodomain inhibitor, CN470, represents a promising therapeutic approach against MLL-r ALL.

Drug resistance to nelarabine in leukemia cell lines might be caused by reduced expression of deoxycytidine kinase through epigenetic mechanisms.

PURPOSE: Drug resistance is a serious problem in leukemia therapy. A novel purine nucleoside analogue, nelarabine, is available for the treatment of children with T cell acute lymphoblastic leukemia. We investigated the mechanisms of drug resistance to nelarabine. METHODS: Nelarabine-resistant cells were selected by stepwise and continuous exposure to nelarabine using the limiting dilution method in human B and T cell lymphoblastic leukemia cell lines. Expression analysis was performed using real-time polymerase chain reaction, and epigenetic analysis was performed using methylation-specific polymerase chain reaction and chromatin immunoprecipitation. RESULTS: The RNA expression level for deoxycytidine kinase (dCK) was decreased in nelarabine-resistant leukemia cells. There were no differences between the parental and nelarabine-resistant leukemia cells in the methylation status of the promoter region of the dCK gene. In the chromatin immune precipitation assay, decreased acetylation of histones H3 and H4 bound to the dCK promoter was seen in the nelarabine-resistant cells when compared to the parental cells. Furthermore, treatment with a novel histone deacetylase inhibitor, vorinostat, promoted the cytotoxic effect of nelarabine along with increased expression of the dCK gene, and it increased acetylation of both histones H3 and H4 bound to the dCK promoter in nelarabine-resistant leukemia cells. The combination index showed that the effect of nelarabine and vorinostat was synergistic. CONCLUSION: This study reports that nelarabine with vorinostat can promote cytotoxicity in nelarabine-resistant leukemia cells through epigenetic mechanisms.

A novel aryl-guanidinium derivative, VP79s, targets the signal transducer and activator of transcription 3 signaling pathway, downregulates myeloid cell leukaemia-1 and exhibits preclinical activity against multiple myeloma.

AIMS: We have recently described a novel guanidinium-based compound, VP79s, which induces cytotoxicity in various cancer cell lines. Here, we aim to investigate the activity of VP79s and associated mechanisms of action in multiple myeloma (MM) cells in vitro and ex vivo. MAIN METHODS: The effects of VP79s on cell viability and induction of apoptosis was examined in a panel of drug-sensitive and drug-resistant MM cell lines, as well as ex vivo patient samples and normal donor lymphocytes and platelets. Cell signaling pathways associated with the biological effects of VP79s were analysed by immunoblotting and flow cytometry. Gene expression changes were assessed by quantitative real-time PCR analysis. KEY FINDINGS: VP79s was found to rapidly inhibit both constitutively active and IL-6-induced STAT3 signaling with concurrent downregulation of the IL-6 receptors, CD130 and CD126. VP79s induced a rapid and dose-dependent downregulation of anti-apoptotic Bcl-2 family member, myeloid cell leukaemia-1 (MCL-1). VP79s enhanced bortezomib induced cell death and was also found to overcome bone marrow stromal cell induced drug resistance. VP79s exhibited activity in ex vivo patient samples at concentrations which had no effect on peripheral blood mononuclear cells, lymphocytes and platelets isolated from healthy donors. SIGNIFICANCE: As VP79s resulted in rapid inhibition of the key IL-6/STAT3 signaling pathway and downregulation of MCL-1 expression with subsequent selective anti-myeloma activity, VP79s may be a potential therapeutic agent with a novel mechanism of action in MM cells.

Simvastatin regulates the proliferation, apoptosis, migration and invasion of human acute myeloid leukemia cells via miR-19a-3p/HIF-1α axis.

Statins are mainly used to lower plasma cholesterol level. In addition, the anti-leukemia effect of statins has been reported, but the mechanism remains unclear.This study aimed to explore the bioregulation of simvastatin and its mechanism in acute leukemia cell lines. Cell viability was detected by CCK-8 analysis. Apoptosis was detected through flow cytometry. Cell invasion and migration both were observed by transwell and wound healing separately. RT-qPCR and Western blot were used for determination of genes and proteins. We found that that simvastatin could regulate the biological functions of acute myeloid leukemia (AML) cells, including its proliferation, migration, invasion and apoptosis, which may be carried out by down-regulating miR-19a-3p. Overexpression of miR-19a-3p had the opposite effect in AML cells, suggesting simvastatin-inhibited AML by reducing miR-19a-3p expression. Following researches showed that HIF-1α was directly regulated by the target of miR-19a-3p. Simvastatin could reverse the adverse effects caused by miR-19a-3p mimics. Conversely, the increased expression of Mcl-1, the inhibition of caspase-3 could promote the growth of AML cells. In conclusion, simvastatin could inhibit the proliferation, migration, invasion and promote apoptosis in AML cells through miR-19a-3p/HIF-1α axis.

Optimal time-points for detecting expression levels of BAALC, EVI1, and WT1 genes in patients with acute myeloid leukemia: a meta-analysis.

OBJECTIVES: This meta-analysis examined the prognostic role of brain and acute leukemia, cytoplasmic (BAALC), Ecotropic virus integration site-1 (EVI1) and Wilms' tumor 1 (WT1) genes at different time-points during conventional chemotherapy. METHODS: A systematic search of publications indexed in the electronic databases from January 1988 to October 2020 was performed. Over 7525 cases of AML from 25 studies were involved. RESULTS: At diagnosis, overexpression of either BAALC or EVI1 had a negative impact on complete remission achievement (Summary Odds ratios [SORs] for BAALC = 0.32; SORs for EVI1 = 0.49) and survival outcome. The summary hazard ratios of overall survival (OS) and disease-free survival (DFS) were 1.97 and 2.04 for BAALC and 1.33 and 1.86 for EVI1, respectively. The prognostic value of pretreatment WT1 levels was heterogeneous while subgroup analyses unveiled that overexpressed WT1 may correlate with a favorable outcome (summary hazard ratio [SHR] for OS = 0.42). Both WT1 and BAALC played a role in prognosis assessment at post-induction and the diagnostic performance of WT1 transcript reduction was superior to the absolute WT1 level. Post-consolidation WT1 overexpression consistently indicated an increased risk of relapse, while the combined HR for RFS was statistically insignificant (SHR = 4.22). CONCLUSION: These findings confirm the application of BAALC and EVI1 at diagnosis, WT1 after induction chemotherapy in AML patients throughout conventional chemotherapy.

High Immunoproteasome Activity and sXBP1 in Pediatric Precursor B-ALL Predicts Sensitivity towards Proteasome Inhibitors.

Proteasome inhibitors (PIs) are approved backbone treatments in multiple myeloma. More recently, inhibition of proteasome activity with the PI bortezomib has been clinically evaluated as a novel treatment strategy in pediatric acute lymphoblastic leukemia (ALL). However, we lack a marker that could identify ALL patients responding to PI-based therapy. By using a set of activity-based proteasome probes in conjunction with cytotoxicity assays, we show that B-cell precursor ALL (BCP-ALL), in contrast to T-ALL, demonstrates an increased activity of immunoproteasome over constitutive proteasome, which correlates with high ex vivo sensitivity to the PIs bortezomib and ixazomib. The novel selective PI LU015i-targeting immunoproteasome ß5i induces cytotoxicity in BCP-ALL containing high ß5i activity, confirming immunoproteasome activity as a novel therapeutic target in BCP-ALL. At the same time, cotreatment with ß2-selective proteasome inhibitors can sensitize T-ALL to currently available PIs, as well as to ß5i selective PI. In addition, levels of total and spliced forms of XBP1 differ between BCP-ALL and T-ALL, and only in BCP-ALL does high-spliced XBP1 correlate with sensitivity to bortezomib. Thus, in BCP-ALL, high immunoproteasome activity may serve as a predictive marker for PI-based treatment options, potentially combined with XBP1 analyses.

Automated CUT&Tag profiling of chromatin heterogeneity in mixed-lineage leukemia.

Acute myeloid and lymphoid leukemias often harbor chromosomal translocations involving the KMT2A gene, encoding the KMT2A lysine methyltransferase (also known as mixed-lineage leukemia-1), and produce in-frame fusions of KMT2A to other chromatin-regulatory proteins. Here we map fusion-specific targets across the genome for diverse KMT2A oncofusion proteins in cell lines and patient samples. By modifying CUT&Tag chromatin profiling for full automation, we identify common and tumor-subtype-specific sites of aberrant chromatin regulation induced by KMT2A oncofusion proteins. A subset of KMT2A oncofusion-binding sites are marked by bivalent (H3K4me3 and H3K27me3) chromatin signatures, and single-cell CUT&Tag profiling reveals that these sites display cell-to-cell heterogeneity suggestive of lineage plasticity. In addition, we find that aberrant enrichment of H3K4me3 in gene bodies is sensitive to Menin inhibitors, demonstrating the utility of automated chromatin profiling for identifying therapeutic vulnerabilities. Thus, integration of automated and single-cell CUT&Tag can uncover epigenomic heterogeneity within patient samples and predict sensitivity to therapeutic agents.