BCL-2 inhibition targets oxidative phosphorylation and selectively eradicates quiescent human leukemia stem cells

Targeting the IKZF1/BCL-2 axis as a novel therapeutic strategy for treating acute T-cell lymphoblastic leukemia

OBJECTIVES

Acute T-cell lymphoblastic leukemia (T-ALL) is a severe hematologic malignancy with limited treatment options and poor long-term survival. This study explores the role of IKZF1 in regulating BCL-2 expression in T-ALL.

METHODS

CUT&Tag and CUT&Run assays were employed to assess IKZF1 binding to the BCL-2 promoter. IKZF1 overexpression and knockdown experiments were performed in T-ALL cell lines. The effects of CX-4945 and venetoclax, alone and in combination, were evaluated in vitro and in vivo T-ALL models.

RESULTS

CUT&Tag sequencing identified IKZF1 binding to the BCL-2 promoter, establishing it as a transcriptional repressor. Functional assays demonstrated that IKZF1 overexpression reduced BCL-2 mRNA levels and increased repressive histone marks at the BCL-2 promoter, while IKZF1 knockdown led to elevated BCL-2 expression. CX-4945, a CK2 inhibitor, could reduced BCL-2 levels in T-ALL cells. Notably, knockdown of IKZF1 partially rescued the CX-4945-induced repression of BCL-2. These results underscore the CK2-IKZF1 signaling axis as a key regulator of BCL-2 expression. In vitro, CX-4945 enhanced the cytotoxicity of venetoclax, with the combination showing significant synergistic effects and increased apoptosis in T-ALL cell lines. In vivo studies with cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) models demonstrated that CX-4945 and venetoclax combined therapy provided superior therapeutic efficacy, reducing tumor burden and prolonging survival compared to single-agent treatments.

CONCLUSIONS

IKZF1 represses BCL-2 in T-ALL, and targeting the CK2-IKZF1 axis with CX-4945 and venetoclax offers a promising therapeutic strategy, showing enhanced efficacy and potential as a novel treatment approach for T-ALL.

The mitochondria as an emerging target of self-renewal in T-cell acute lymphoblastic leukemia

Acute lymphocytic leukemia (ALL) is the most common leukemia in children, with the T-cell subtype (T-ALL) accounting for 15% of those cases. Despite advancements in the treatment of T-ALL, patients still face a dismal prognosis following their first relapse. Relapse can be attributed to the inability of chemotherapy agents to eradicate leukemia stem cells (LSC), which possess self-renewal capabilities and are responsible for the long-term maintenance of the disease. Mitochondria have been recognized as a therapeutic vulnerability for cancer stem cells, including LSCs. Mitocans have shown promise in T-ALL both in vitro and in vivo, with some currently in early-phase clinical trials. However, due to challenges in studying LSCs in T-ALL, our understanding of how mitochondrial function influences self-renewal remains limited. This review highlights the emerging literature on targeting mitochondria in diverse T-ALL models, emphasizing specific mitochondrial vulnerabilities linked to LSC self-renewal and their potential to significantly improve T-ALL treatment.

3-Bromopyruvate boosts the effect of chemotherapy in acute myeloid leukemia by a pro-oxidant mechanism

Acute myeloid leukemia (AML) comprises a diverse group of blood cancers with varying genetic, phenotypic, and clinical traits, making development of targeted therapy challenging. Metabolic reprogramming in AML has been described as relevant for chemotherapy effectiveness. 3-Bromopyruvate (3-BP) is an anticancer agent that undermines energy metabolism of cancer cells. However, the effect of 3-BP in hematologic malignancies, such as AML, needs further investigation. Thus, we aimed to explore 3-BP as a chemo-sensitizing agent in AML. Different approaches of combining 3-BP with classical chemotherapy (daunorubicin and cytarabin) were tested in diverse AML cell lines. Cell sensitivity to the different drug combinations was analyzed by Trypan blue staining. The effect of pre-treatment with a non-toxic concentration of 3-BP was assessed on the AML cell metabolic profile (Western blot and immunofluorescence), mitochondrial activity (cytometry flow), and antioxidant capacity (colorimetric detection kit). KG-1 and MOLM13 cells showed increased sensitivity to chemotherapy (decreased EC50 values) after exposure to a non-toxic concentration (5 μM) of 3-BP. In both cell lines, 5 μM 3-BP decreased glucose consumption without changing extracellular lactate levels. 5 μM 3-BP treatment increased reactive oxygen species levels and decreased cell antioxidant capacity by depleting reduced glutathione levels in both KG-1 and MOLM13 cells. Our results demonstrate that non-toxic concentrations of 3-BP enhance the effect of classical chemotherapy in AML cells through a pro-oxidant mechanism. These data unveiled a new approach for AML treatment, using 3-BP or other pro-oxidant agents as co-adjuvants of chemotherapy, subsiding chemotherapy-induced side effects.

STAT1 inhibition promotes oxidative stress to sustain leukemia stem cell maintenance

New strategy to prevent relapse and drug resistance in acute myeloid leukemia (AML) is urgently to be solved. The connection between those properties and leukemia stem cells (LSCs) in AML remains poorly understood. In this study, we demonstrate that leukemia cells with high signal transducer and activator of transcription 1 (STAT1) expression preserve quiescent properties, in contrast, leukemia cells with low STAT1 expression possess active and vulnerable apoptotic properties in AML model, highlighting the differential impact of STAT1 expression on cellular behavior in acute myeloid leukemia. STAT1 depletion damages the quiescence of LSCs and prolongs the survive of AML mice. By inhibiting STAT1 in leukemia cells, we observe a significant elevation in reactive oxygen species (ROS) levels, rendering the cells more susceptible to the detrimental effects of oxidative stress. The synergistic administration of Fludarabine, a potent STAT1 inhibitor, with conventional chemotherapy regimens, augments the efficacy of chemotherapy drugs against AML cells and the sensitivity of LSCs to chemotherapy. In a word, STAT1, as a switch, enables leukemia cells convertible in ROS high and low states. Inhibition of STAT1 enables leukemia cells more sensitive to chemotherapy, STAT1 as a new target offers a promising strategy in AML treatment.

Unraveling Venetoclax Resistance: Navigating the Future of HMA/Venetoclax-Refractory AML in the Molecular Era

Acute myeloid leukemia (AML) has traditionally been linked to a poor prognosis, particularly in older patients who are ineligible for intensive chemotherapy. The advent of Venetoclax, a powerful oral BH3 mimetic targeting anti-apoptotic protein BCL2, has significantly advanced AML treatment. Its combination with the hypomethylating agent azacitidine (AZA/VEN) has become a standard treatment for this group of AML patients, demonstrating a 65% overall response rate and a median overall survival of 14.7 months, compared to 22% and 8 months with azacitidine monotherapy, respectively. However, resistance and relapses remain common, representing a significant clinical challenge. Recent studies have identified molecular alterations, such as mutations in FLT3-ITD, NRAS/KRAS, TP53, and BAX, as major drivers of resistance. Additionally, other factors, including metabolic changes, anti-apoptotic protein expression, and monocytic or erythroid/megakaryocytic differentiation status, contribute to treatment failure. Clinical trials are exploring strategies to overcome venetoclax resistance, including doublet or triplet therapies targeting IDH and FLT3 mutations; novel epigenetic approaches; menin, XPO1, and MDM2 inhibitors; along with immunotherapies like monoclonal antibodies and antibody-drug conjugates. A deeper understanding of the molecular mechanisms of resistance through single-cell analysis will be crucial for developing future therapeutic strategies.

Unveiling vitamin C: A new hope in the treatment of diffuse large B‑cell lymphoma (Review)

Lymphoma is a malignancy of the immune system, which originates from lymphatic tissues and lymph nodes. Diffuse large B‑cell lymphoma (DLBCL) is a common type of non‑Hodgkin lymphoma, occurring in 30‑40% of all cases, which has persistent clinical challenges. The treatment of DLBCL is challenging due to its diverse genetic and biological characteristics and complex clinical physiology. Despite advancements in overall prognosis, 20‑25% of patients continue to experience relapse and 10‑15% of patients experience refractory disease. Vitamin C is a water‑soluble vitamin with antioxidant properties and notable pharmacological activity, with potential applications in cancer therapy. Pharmacological doses of vitamin C (1‑4 g/kg) can induce apoptosis in malignant cells by inhibiting and/or reversing gene mutations that are associated with hematological malignancies. For example, 10‑25% of patients with myeloid malignancies have tet methylcytosine dioxygenase 2 (TET2) gene mutations and vitamin C can regulate blood stem cell frequency and leukemia production by enhancing TET2 function. Consequently, pharmacological doses of vitamin C can inhibit the development and progression of hematological malignancies. Therefore, the present review aimed to investigate the role of vitamin C in the pathophysiology and treatment of DLBCL, whilst highlighting the potential challenges and future perspectives.

Targeted Penetrating Motif Engineering of BH3 Mimetic: Harnessing Non-Canonical Amino Acids for Coinhibition of MCL-1 and BCL-xL in Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) remains a formidable clinical challenge, predominantly due to the emergence of resistance to existing therapeutic regimens, including BCL-2 inhibitors like Venetoclax. Here, a novel approach is introduced by engineering BH3 mimetics utilizing non-canonical amino acids (ncAAs) to achieve dual inhibition of MCL-1 and BCL-xL. Through site saturation mutagenesis scanning, the I58(Chg) mutation is identified, significantly enhancing binding affinity with IC50 values of 2.77 nm for MCL-1 and 10.69 nm for BCL-xL, reflecting an increase of fourfold or more. The developed vMIP-II-TAT-I peptide, incorporating a CXCR4-targeted penetrating motif, demonstrated superior cellular uptake, with mean fluorescence intensity (MFI) 7.2-fold higher in CXCR4-positive AML cells and exhibited a high selectivity index (SI) for AML cells, with minimal impact on normal human hematopoietic stem cells (HSCs). When combined with Venetoclax, this peptide induced synergistic apoptosis, reducing tumor burden and prolonging survival in an AML mouse model, with median survival extended to 53 days from 37 days with Venetoclax alone. These findings reveal the therapeutic potential of dual inhibition in overcoming Venetoclax resistance and selectively targeting leukemic cells with reduced off-target effects, while laying the foundation for developing advanced BH3 mimetics with enhanced targeting, binding affinity, and efficacy for AML treatment.

From Chemotherapy to Targeted Therapy: Unraveling Resistance in Acute Myeloid Leukemia Through Genetic and Non-Genetic Insights

Acute myeloid leukemia (AML) is a devastating disease characterized by extensive inter-patient and intra-patient heterogeneity. Despite the introduction of intensive chemotherapy in the 1970s as the standard treatment, the development of mechanism-based targeted therapies since 2017 has been broadening the therapeutic landscape. However, both chemotherapy and targeted therapies continue to face the challenges of primary and secondary resistance. This review summarizes the mechanisms underlying resistance to chemotherapy and targeted therapies in AML and discusses the opportunities and challenges brought by the transition from chemotherapy to precision medicine.

Supinoxin blocks small cell lung cancer progression by inhibiting mitochondrial respiration through DDX5

DDX5 is a DEAD-box RNA helicase that is overexpressed and implicated in the progression of several cancers, including small cell lung cancer (SCLC). Our laboratory has demonstrated that DDX5 is essential for the invasive growth of SCLC and mitochondrial respiration. SCLC is an extremely lethal, recalcitrant tumor, and currently lacking effective treatments. Supinoxin (RX 5902), a compound having anti-cancer activity, is a known target of phosphor-DDX5. We now report that Supinoxin inhibits the proliferation of chemo-sensitive and chemo-resistant SCLC lines, H69 and H69AR, respectively. Additionally, Supinoxin mitigates both the growth of H69AR xenograft tumors and SCLC PDX tumors in vivo. Finally, we find that Supinoxin inhibits expression of mitochondrial genes and effectively blocks respiration. These studies suggest that Supinoxin functions in anti-tumor progression by reducing cellular energy levels through DDX5.

Understanding and Targeting Metabolic Vulnerabilities in Acute Myeloid Leukemia: An Updated Comprehensive Review

Acute Myeloid Leukemia (AML) is characterized by aggressive proliferation and metabolic reprogramming that support its survival and resistance to therapy. This review explores the metabolic distinctions between AML cells and normal hematopoietic stem cells (HSCs), emphasizing the role of altered mitochondrial function, oxidative phosphorylation (OXPHOS), and biosynthetic pathways in leukemic progression. AML cells exhibit distinct metabolic vulnerabilities, including increased mitochondrial biogenesis, reliance on glycolysis and amino acid metabolism, and unique signaling interactions that sustain leukemic stem cells (LSCs). These dependencies provide potential therapeutic targets, as metabolic inhibitors have demonstrated efficacy in disrupting AML cell survival while sparing normal hematopoietic cells. We examine current and emerging metabolic therapies, such as inhibitors targeting glycolysis, amino acid metabolism, and lipid biosynthesis, highlighting their potential in overcoming drug resistance. However, challenges remain in translating these strategies into clinical practice due to AML's heterogeneity and adaptability. Further research into AML's metabolic plasticity and precision medicine approaches is crucial for improving treatment outcomes. Understanding and exploiting AML's metabolic vulnerabilities could pave the way for novel, more effective therapeutic strategies.

Interactions between leukemia and feeders in co-cultivation under hypoxia

BACKGROUND

Leukemia is driven by complex interactions within the inherently hypoxic bone marrow microenvironment, impacting both disease progression and therapeutic resistance. Co-cultivation of leukemic cells with feeder cells has emerged as a valuable tool to mimic the bone marrow niche. This study explores the interplay between human commercial SD-1 and patient-derived UPF26K leukemic cell lines with feeders - human fibroblasts (NHDF) and mesenchymal stem cells (hMSCs) under normoxic and hypoxic conditions.

RESULTS

Co-cultivation with feeders significantly enhances proliferation and glycolytic activity in the SD-1 cells, improving their viability, while this interaction inhibits the growth and glucose metabolism of the feeders, particularly NHDF. In contrast, UPF26K cells show reduced proliferation when co-cultivated with the feeders while this interaction stimulates NHDF and hMSCs proliferation and glycolysis but reduce their mitochondrial metabolism with hypoxia amplifying these effects.

CONCLUSIONS

Cells that switch to glycolysis during co-cultivation, particularly under hypoxia, benefit most from these low oxygen conditions. Due to this leukemic cells' response heterogeneity, targeting microenvironmental interactions and oxygen levels is crucial for personalized leukemia therapy. Advancing co-cultivation models, particularly through innovations like spheroids, can further enhance in vitro studies of primary leukemic cells and support the testing of novel therapies.

The Importance of Cancer Stem Cells and Their Pathways in Endometrial Cancer: A Narrative Review

Endometrial cancer is one of the most common malignancies seen in women in developed countries. While patients in the early stages of this cancer show better responses to surgery, adjuvant hormonal therapy, and chemotherapy, patients with recurrence show treatment resistance. Researchers have recently focused on cancer stem cells (CSCs) in the treatment of gynecologic cancer in general but also specifically in endometrial cancer. CSCs have been investigated because of their resistance to conventional therapies, such as chemo- and radiotherapy, and their ability to induce the progression and recurrence of malignancy. The activation of alternative pathways, such as WNT, PI3K, NF-kB, or NOTCH, could be the basis of the acquisition of these abilities of CSCs. Their specific markers and signaling pathways could be treatment targets for CSCs. In this article, we discuss the importance of obtaining a better understanding of the molecular basis and pathways of CSCs in endometrial cancer and the role of CSCs, aiming to discover more specific therapeutic approaches.

A common ground: an in silico assessment of the sources of intrinsic ex vivo resistance to venetoclax in acute myeloid leukemia

Venetoclax is a promising alternative for patients with acute myeloid leukemia who are considered unfit for conventional chemotherapy; however, its employment still faces challenges mostly related to drug resistance. Here, we provide further biological mechanisms underlying the previously described and potentially novel intrinsic sources of poor response to venetoclax departing from ex vivo response data. Acute myeloid leukemia data including FLT3 mutation status, gene expression data, and ex vivo response data were extracted from the publicly available BeatAML 1.0 study database and aided sample categorization that supported differential gene expression analysis that, in turn, supported gene set enrichment analysis. CIBERSORTx-based bulk RNA sequencing deconvolution of BeatAML 1.0 data allowed us to categorize samples according to their cell type content. We observed that inflammation-related gene sets, such as cytokines and inflammatory response, NLRP3 inflammasome activation, and activation of adaptive immune response, were concordantly positively enriched across all the conditions reported to be associated with poor ex vivo venetoclax response, whereas samples from good ex vivo responders' mostly enriched gene sets related to mitochondrial activity, and early myeloid progenitor cell molecular programs. Besides the alternative reliance on BCL2A1, we highlight inflammation as a common element present across multiple sources of venetoclax ex vivo response modulation in acute myeloid leukemia samples. Hence, a potential key modulator for venetoclax response.

Acute myeloid leukemia mitochondria hydrolyze ATP to support oxidative metabolism and resist chemotherapy

OxPhos inhibitors have struggled to show a clinical benefit because of their inability to distinguish healthy from cancerous mitochondria. Herein, we describe an actionable bioenergetic mechanism unique to acute myeloid leukemia (AML) mitochondria. Unlike healthy cells that couple respiration to ATP synthesis, AML mitochondria support inner-membrane polarization by consuming ATP. Matrix ATP consumption allows cells to survive bioenergetic stress. Thus, we hypothesized AML cells may resist chemotherapy-induced cell death by reversing the ATP synthase reaction. In support, BCL-2 inhibition with venetoclax abolished OxPhos flux without affecting mitochondrial polarization. In surviving AML cells, sustained mitochondrial polarization depended on matrix ATP consumption. Mitochondrial ATP consumption was further enhanced in AML cells made refractory to venetoclax, consequential to down-regulations in the endogenous F1-ATPase inhibitor ATP5IF1. Knockdown of ATP5IF1 conferred venetoclax resistance, while ATP5IF1 overexpression impaired F1-ATPase activity and heightened sensitivity to venetoclax. These data identify matrix ATP consumption as a cancer cell-intrinsic bioenergetic vulnerability actionable in the context of BCL-2 targeted chemotherapy.

Enhancing venetoclax efficacy in leukemia through association with HDAC inhibitors

Epigenetic modifications significantly influence gene expression and play crucial roles in various biological processes, including carcinogenesis. This study investigates the effects of novel purine-benzohydroxamate compounds, particularly 4 f, as hybrid kinase/histone deacetylase (HDAC) inhibitors in hematological malignancies, focusing on acute myeloid leukemia (AML). Our results demonstrate that these compounds selectively reduce cell viability in blood cancer cells, with inhibitory concentration values indicating higher potency against neoplastic cells compared to normal leukocytes. Mechanistically, 4 f induces apoptosis and cell cycle arrest, promoting differentiation in leukemia cells, while effectively inhibiting HDAC activity. Furthermore, 4 f enhances the therapeutic efficacy of venetoclax, a BCL2 inhibitor, in AML models sensitive and resistant to this drug. The combination treatment significantly increases apoptosis and reduces cell viability, suggesting a synergistic effect that may overcome drug resistance. This study provides valuable insights into the potential of HDAC inhibitors, particularly 4 f, as a promising therapeutic strategy for treating resistant hematological malignancies. Our findings underscore the importance of further exploring hybrid kinase/HDAC inhibitors in combination therapies to improve outcomes in patients with acute leukemias and other hematological malignancies.

Omics approaches: Role in acute myeloid leukemia biomarker discovery and therapy

Acute myeloid leukemia (AML) is the most common acute leukemia in adults and has the highest fatality rate. Patients aged 65 and above exhibit the poorest prognosis, with a mere 30 % survival rate within one year. One important issue in optimizing outcomes for AML patients is their limited ability to predict responses to specific therapies, response duration, and likelihood of relapse. Despite rigorous therapeutic interventions, a significant proportion of patients experience relapse. Consequently, there is a pressing need to introduce new targets for therapy. Sequencing and biotechnology have come a long way in the last ten years. This has made it easier for many omics technologies, like genomics, transcriptomics, proteomics, and metabolomics, to study molecular mechanisms of AML. An integrative approach is necessary to understand a complex biological process fully and offers an important opportunity to understand the information underlying diseases. In this review, we studied papers published between 2010 and 2024 employing omics approaches encompassing diagnosis, prognosis, and risk stratification of AML. Finally, we discuss prospects and challenges in applying -omics technologies to the discovery of novel biomarkers and therapy targets. Our review may be helpful for omics researchers who want to study AML from different molecular aspects.

Distinct leukemogenic mechanism of acute promyelocytic leukemia based on genomic structure of PML::RARα

Leukemic stem cells (LSCs) of acute myeloid leukemia (AML) can be enriched in the CD34+CD38- fraction and reconstitute human AML in vivo. However, in acute promyelocytic leukemia (APL), which constitutes 10% of all AML cases and is driven by promyelocytic leukemia-retinoic acid receptor alpha (PML::RARα) fusion genes, the presence of LSCs has long been unidentified because of the difficulty in efficient reconstitution of human APL in vivo. Herein, we show that LSCs of the short-type isoform APL, a subtype of APL defined by different breakpoints of the PML gene, concentrate in the CD34+CD38- fraction and express T cell immunoglobulin mucin-3 (TIM-3). Short-type APL cells exhibited distinct gene expression signatures, including LSC-related genes, compared to the other types of APL. Moreover, CD34+CD38-TIM-3+ short-type APL cells efficiently reconstituted human APL in xenograft models with high penetration, whereas CD34- differentiated APL cells did not. Furthermore, CD34+CD38-TIM-3+ short-type APL cells reconstituted leukemia cells after serial transplantation. Thus, short-type APL was hierarchically organized by self-renewing APL-LSCs. The identification of LSCs in a subset of APL and establishment of an efficient patient-derived xenograft model may contribute to further understanding the APL leukemogenesis and devise individual treatments for the eradication of APL LSCs.

Phosphatidic acid phosphatase LPIN1 in phospholipid metabolism and stemness in hematopoiesis and AML

Targeting metabolism represents a promising approach to eradicate leukemic stem cells (LSCs) that are considered critical drivers of relapse in acute myeloid leukemia (AML). In this study, we demonstrate that the phosphatidic acid phosphatase LPIN1, which regulates the synthesis of diacylglycerol, the key substrate for triacylglycerol, and phospholipid production, is crucial for the function of healthy and leukemic hematopoietic stem and progenitor cells (HSPC and LSC). LPIN1 mRNA was highly expressed in the CD34+ compartment of primary human AML samples. LPIN1 suppression inhibited the proliferation of primary leukemic cells and normal HSPCs in vitro and in xenotransplantation assays. Lipidomics analyses revealed a reduction of phosphatidylcholine (PC) and phosphatidylethanolamine and an upregulation of sphingomyelin upon LPIN1 depletion. Distinct phospholipid composition was associated with genetic AML groups, and targeting PC production by choline kinase inhibitors showed strong anti-leukemic activity. In summary, our data establish a regulatory role of LPIN1 in HSPC and LSC function and provide novel insights into the role of glycerophospholipid homeostasis in stemness and differentiation.

Preclinical targeting of leukemia-initiating cells in the development future biologics for acute myeloid leukemia

INTRODUCTION

Leukemia-initiating cells (LICs) are a critical subset of cells driving acute myeloid leukemia (AML) relapse and resistance to therapy. They possess unique properties, including metabolic, epigenetic, and microenvironmental dependencies, making them promising therapeutic targets.

AREAS COVERED

This review summarizes preclinical advances in targeting AML LICs, including strategies to exploit metabolic vulnerabilities, such as the reliance on oxidative phosphorylation (OXPHOS), through the use of mitochondrial inhibitors; target epigenetic regulators like DOT1L (Disruptor of Telomeric Silencing 1-like) to disrupt LIC survival mechanisms; develop immunotherapies, including CAR (chimeric antigen receptor) T-cell therapy, and bispecific antibodies; and disrupt LIC interactions with the bone marrow microenvironment by inhibiting supportive niches.

EXPERT OPINION

LIC-targeted therapies hold significant promise for revolutionizing AML treatment by reducing relapse rates and improving long-term outcomes. However, challenges such as LIC heterogeneity, therapy resistance, and associated toxicity persist. Recent studies have illuminated the distinct biological characteristics of LICs, advancing our understanding of their behavior and vulnerabilities. These insights offer new opportunities to target LICs at earlier disease stages and to explore combination therapies with other targeted treatments, ultimately enhancing therapeutic efficacy and improving patient outcomes.

Glycolysis-Driven Prognostic Model for Acute Myeloid Leukemia: Insights into the Immune Landscape and Drug Sensitivity

Background: Acute myeloid leukemia (AML), a malignant blood disease, is caused by the excessive growth of undifferentiated myeloid cells, which disrupt normal hematopoiesis and may invade several organs. Given the high heterogeneity in prognosis, identifying stable prognostic biomarkers is crucial for improved risk stratification and personalized treatment strategies. Although glycolysis has been extensively studied in cancer, its prognostic significance in AML remains unclear. Methods: Glycolysis-related prognostic genes were identified by differential expression profiles. We modeled prognostic risk by least absolute shrinkage and selection operator (LASSO) regression and validated it by Kaplan-Meier (KM) survival analysis, receiver operating characteristic (ROC) curves, and independent datasets (BeatAML2.0, GSE37642, GSE71014). Mechanisms were further explored through immune microenvironment analysis and drug sensitivity scores. Results: Differential expression and survival correlation analysis across the genes associated with glycolysis revealed multiple glycolytic genes associated with the outcomes of AML. We constructed a seven-gene prognostic model (G6PD, TFF3, GALM, SOD1, NT5E, CTH, FUT8). Kaplan-Meier analysis demonstrated significantly reduced survival in high-risk patients (hazard ratio (HR) = 3.4, p < 0.01). The model predicted the 1-, 3-, and 5-year survival outcomes, achieving area under the curve (AUC) values greater than 0.8. Immune profiling indicated distinct cellular compositions between risk groups: high-risk patients exhibited elevated monocytes and neutrophils but reduced Th1 cell infiltration. Drug sensitivity analysis showed that high-risk patients exhibited resistance to crizotinib and lapatinib but were more sensitive to motesanib. Conclusions: We established a novel glycolysis-related gene signature for AML prognosis, enabling effective risk classification. Combined with immune microenvironment analysis and drug sensitivity analysis, we screened metabolic characteristics and identified an immune signature to provide deeper insight into AML. Our findings may assist in identifying new therapeutic targets and more effective personalized treatment regimes.

A quiescence-like/TGF-β1-specific CRISPRi screen reveals drug uptake transporters as secondary targets of kinase inhibitors in AML

Relapse in acute myeloid leukemia (AML) is driven by resistant subclones that survive chemotherapy. It is assumed that these resilient leukemic cells can modify their proliferative behavior by entering a quiescent-like state, similar to healthy hematopoietic stem cells (HSCs). These dormant cells can evade the effects of cytostatic drugs that primarily target actively dividing cells. Although quiescence has been extensively studied in healthy hematopoiesis and various solid cancers, its role in AML has remained unexplored. In this study, we applied an HSC-derived quiescence-associated gene signature to an AML patient cohort and found it to be strongly correlated with poor prognosis and active TGF-β signaling. In vitro treatment with TGF-β1 induces a quiescence-like phenotype, resulting in a G0 shift and reduced sensitivity to cytarabine. To find potential therapeutic targets that prevent AML-associated quiescence and improve response to cytarabine, we conducted a comprehensive CRISPR interference (CRISPRi) screen combined with TGF-β1 stimulation. This approach identified TGFBR1 inhibitors, like vactosertib, as effective agents for preventing the G0 shift in AML cell models. However, pretreatment with vactosertib unexpectedly induced complete resistance to cytarabine. To elucidate the underlying mechanism, we performed a multi-faceted approach combining a second CRISPRi screen, liquid chromatography-tandem mass spectrometry (LC-MS/MS), and in silico analysis. Our findings revealed that TGFBR1 inhibitors unintentionally target the nucleoside transporter SLC29A1 (ENT1), leading to reduced intracellular cytarabine levels. Importantly, we found that this drug interaction is not unique to TGFBR1 inhibitors, but extends to other clinically significant kinase inhibitors, such as the FLT3 inhibitor midostaurin. These findings may have important implications for optimizing combination therapies in AML treatment.

α-Ketoglutarate dehydrogenase is a therapeutic vulnerability in acute myeloid leukemia

ABSTRACT

Perturbations in intermediary metabolism contribute to the pathogenesis of acute myeloid leukemia (AML) and can produce therapeutically actionable dependencies. Here, we probed whether α-ketoglutarate (αKG) metabolism represents a specific vulnerability in AML. Using functional genomics, metabolomics, and mouse models, we identified the αKG dehydrogenase complex, which catalyzes the conversion of αKG to succinyl coenzyme A, as a molecular dependency across multiple models of adverse-risk AML. Inhibition of 2-oxoglutarate dehydrogenase (OGDH), the E1 subunit of the αKG dehydrogenase complex, impaired AML progression and drove differentiation. Mechanistically, hindrance of αKG flux through the tricarboxylic acid (TCA) cycle resulted in rapid exhaustion of aspartate pools and blockade of de novo nucleotide biosynthesis, whereas cellular bioenergetics was largely preserved. Additionally, increased αKG levels after OGDH inhibition affected the biosynthesis of other critical amino acids. Thus, this work has identified a previously undescribed, functional link between certain TCA cycle components and nucleotide biosynthesis enzymes across AML. This metabolic node may serve as a cancer-specific vulnerability, amenable to therapeutic targeting in AML and perhaps in other cancers with similar metabolic wiring.

How I treat patients with AML using azacitidine and venetoclax

ABSTRACT

Venetoclax (VEN) received full approval in October 2020 for use in older patients who are unfit with acute myeloid leukemia (AML) combined with either hypomethylating agents or low-dose cytarabine. This ended a semicentennial of stalled clinical progress and initiated a new treatment option with proven capacity to enhance response and prolong survival in older patients with AML. Despite widespread use of azacitidine-VEN (AZA-VEN), there is increasing appreciation that this regimen is myelosuppressive and associated with a higher risk of infectious complications than AZA alone. Key principles of initial management include prevention of tumor lysis syndrome in patients at high risk and minimizing infectious complications during induction. In the postremission phase, limiting cumulative marrow suppression by allowing sufficient time between cycles for optimal marrow recovery and truncating the duration of VEN exposure for those with delayed blood count recovery have emerged as important axioms of effective care. This article casts a clinical spotlight on important challenges and dilemmas encountered in practice. We also outline a structured framework to assist in the safe management of AZA-VEN in the clinic.

Ruxolitinib as a novel therapeutic agent targeting mitochondrial function and chemo-resistance in nasopharyngeal carcinoma

Chemo-resistance poses a significant obstacle in the effective treatment of nasopharyngeal carcinoma (NPC). To identify novel therapeutic strategies, we conducted high-throughput drug screening using a kinase-focused compound library on chemo-resistant NPC cells and normal human nasopharyngeal epithelial cells (HNECs). The screen identified several compounds with known anti-NPC activities, validating the robustness of the approach, and highlighted ruxolitinib, a Janus kinase (JAK) inhibitor, as a novel candidate. Ruxolitinib demonstrated selective cytotoxicity against NPC cells and exhibited strong synergy with 5-FU and cisplatin, significantly enhancing cytotoxicity in chemo-resistant cell lines. Mechanistic studies revealed that ruxolitinib disrupted mitochondrial bioenergetics through selectively inhibiting complex I activity, leading to reduced oxygen consumption rates, ATP production, and cell viability. In a chemo-resistant NPC mouse model, ruxolitinib delayed tumor growth, reduced tumor cell proliferation as indicated by decreased Ki67 staining, and extended overall survival without affecting body weight, demonstrating its efficacy and safety in vivo. These findings position ruxolitinib as a promising therapeutic agent for overcoming chemo-resistance in NPC, warranting further investigation into its clinical potential.

Guanine nucleotide biosynthesis blockade impairs MLL complex formation and sensitizes leukemias to menin inhibition

Targeting the dependency of MLL-rearranged (MLLr) leukemias on menin with small molecule inhibitors has opened new therapeutic strategies for these poor-prognosis diseases. However, the rapid development of menin inhibitor resistance calls for combinatory strategies to improve responses and prevent resistance. Here we show that leukemia stem cells (LSCs) of MLLr acute myeloid leukemia (AML) exhibit enhanced guanine nucleotide biosynthesis, the inhibition of which leads to myeloid differentiation and sensitization to menin inhibitors. Mechanistically, targeting inosine monophosphate dehydrogenase 2 (IMPDH2) reduces guanine nucleotides and rRNA transcription, leading to reduced protein expression of LEDGF and menin. Consequently, the formation and chromatin binding of the MLL-fusion complex is impaired, reducing the expression of MLL target genes. Inhibition of guanine nucleotide biosynthesis or rRNA transcription further suppresses MLLr AML when combined with a menin inhibitor. Our findings underscore the requirement of guanine nucleotide biosynthesis in maintaining the function of the LEDGF/menin/MLL-fusion complex and provide a rationale to target guanine nucleotide biosynthesis to sensitize MLLr leukemias to menin inhibitors.

The Role of the Sirtuin Family Histone Deacetylases in Acute Myeloid Leukemia-A Promising Road Ahead

Acute myeloid leukemia (AML) corresponds to a heterogeneous group of clonal hematopoietic diseases, which are characterized by uncontrolled proliferation of malignant transformed myeloid precursors and their inability to differentiate into mature blood cells. The prognosis of AML depends on many variables, including the genetic features of the disease. Treatment outcomes, despite the introduction of new targeted therapies, are still unsatisfactory. Recently, there have been an increasing number of reports on enzymatic proteins of the sirtuin family and their potential importance in cancer in general. Sirtuins are a group of 7 (SIRT1-7) NAD+-dependent histone deacetylases with pleiotropic effects on metabolism, aging processes, and cell survival. They are not only responsible for post-translational modification of histones but also play various biochemical functions and interact with other proteins regulating cell survival, such as p53. Thus, their role in key mechanisms of tumorigenesis makes them a worthwhile topic in AML. Different sirtuins have been shown to act oppositely depending on the biological context, the mechanism of which requires further exploration. This review provides a comprehensive description of the significance and role of sirtuins in AML in light of the current state of knowledge. It focuses in particular on molecular mechanisms regulated by sirtuins and signaling pathways involved in leukemogenesis, as well as clinical aspects and potential therapeutic targets in AML.

Estrogen-related receptor alpha (ERRα) controls the stemness and cellular energetics of prostate cancer cells via its direct regulation of citrate metabolism and zinc transportation

Compared to most tumors that are more glycolytic, primary prostate cancer is less glycolytic but more dependent on TCA cycle coupled with OXPHOS for its energy demand. This unique metabolic energetic feature is attributed to activation of mitochondrial m-aconitase in TCA caused by decreased cellular Zn level. Evidence suggests that a small subpopulation of cancer cells within prostate tumors, designated as prostate cancer stem cells (PCSCs), play significant roles in advanced prostate cancer progression. However, their cellular energetics status is still poorly understood. Nuclear receptor ERRα (ESRRA) is a key regulator of energy metabolism. Previous studies characterize that ERRα exhibits an upregulation in prostate cancer and can perform multiple oncogenic functions. Here, we demonstrate a novel role of ERRα in the control of stemness and energetics metabolism in PCSCs via a mechanism of combined transrepression of Zn transporter ZIP1 in reducing intracellular Zn uptake and transactivation of ACO2 (m-aconitase) in completion of TCA cycle. Results also showed that restoration of Zn accumulation by treatment with a Zn ionophore Clioquinol could significantly suppress both in vitro growth of PCSCs and also their in vivo tumorigenicity, implicating that enhanced cellular Zn uptake could be a potential therapeutic approach for targeting PCSCs in advanced prostate cancer.

Unraveling lipid metabolism for acute myeloid leukemia therapy

PURPOSE OF REVIEW

The aim of this review is to highlight the importance of lipids' intricate and interwoven role in mediating diverse acute myeloid leukemia (AML) processes, as well as potentially novel lipid targeting strategies. This review will focus on new studies of lipid metabolism in human leukemia, particularly highlighting work in leukemic stem cells (LSCs), where lipids were assessed directly as a metabolite.

RECENT FINDINGS

Lipid metabolism is essential to support LSC function and AML survival through diverse mechanisms including supporting energy production, membrane composition, signaling pathways, and ferroptosis. Recent work has highlighted the role of lipid rewiring in metabolic plasticity which can underlie therapy response, the impact of cellular and genetic heterogeneity in AML on lipid metabolism, and the discovery of noncanonical roles of lipid related proteins in AML.

SUMMARY

Recent findings around lipid metabolism clearly demonstrates their importance to our understanding and therapeutic targeting of AML. We have only begun to unravel the regulation and utilization of lipids in this disease. Further, understanding the layered dynamics of lipid homeostasis could provide novel opportunities to target lipid metabolism in AML and LSCs with the potential of improving outcomes for patients with AML.

Frontline Therapy of AML in the Fit and Younger Population-Incorporating Molecularly Targeted Agents

Backbone therapy for acute myeloid leukemia for younger adults has for 50 years been based on a combination of cytarabine and anthracycline. Over the past 10 years the addition of several targeted agents has been found to improve the outcomes of subsets of AML with particular molecular changes. In this review we will examine the data generated to date on the addition of agents targeting CD33, FLT3, IDH, and BCL2 to standard high intensity therapies. We will also review the potential for future studies evaluating the application of highly active lower intensity therapies developed in older adults to patients considered "fit for high intensity induction." Lastly, we review the data around the role of stem cell transplant in the modern targeted era.

Phase 2 study of chidamide in combination with CAG and venetoclax-azacitidine in older patients with newly diagnosed acute myeloid leukemia

Introduction

Older patients with acute myeloid leukemia (AML) respond poorly to standard induction therapy. DNA methyltransferases (DNMTs) and histone-deacetylases (HDACs) are key regulators of gene expression in cells and have been investigated as important therapeutic targets. However, their effects remains unclear as induction therapy for AML.

Methods

Previously untreated AML patients aged 60 years and over (N=40) were enrolled into this single arm, open-label, phase 2 study to evaluate the clinical efficacy and safety of chidamide combined with CAG and venetoclax-azacitidine (referred to as CACAG-VEN) in elderly AML patients (ClinicalTrials.gov:NCT05659992). All patients received induction treatment with aclarubicin (10 mg/m2/d on days 1, 3, and 5), azacitidine (75 mg/m2 on days 1-7), cytarabine (75 mg/m2 bid on days 1-5), chidamide (30 mg, twice/week for 2 weeks), and venetoclax (100 mg on day 1, 200 mg on day 2, 400 mg on days 3-14). Granulocyte colony-stimulating factor 5 mg/kg/day was administered.

Results

Theoverall response rate was 97.5%, with a composite complete response (CRc) rate of 85.0% after one cycle of CACAG-VEN. Patients with adverse risk according to the ELN guidelines had CRc rates of 81.3%. No patients experienced early death within 30 days of therapy initiation. Grade 3 - 4 non-hematological adverse events included febrile neutropenia in 15 (37.5%) of 40 patients, pneumonia in three (7.5%), sepsis in two (5.0%) and blood bilirubin increase in one (2.5%). The 12-month overall survival rate was 73.4% (95% CI: 55.9-84.8%). The median time to recovery was 15.0 (IQR 10.0-19.5) days for platelets ≥ 20000/mL and 13.0 (IQR 10.5-17.0) days for an absolute neutrophil count ≥ 1000 cells/mL after induction therapy.

Discussion

In conclusion, chidamide in combination with CAG and venetoclaxazacitidine was effective and well tolerated in elderly patients with AML.

Clinical trial registration

https://www.clinicaltrials.gov/, identifier NCT05659992.

TIFAB modulates metabolic pathways in KMT2A::MLLT3-induced AML through HNF4A

ABSTRACT

Tumor necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain B (TIFAB), an inhibitor of NF-κB signaling, plays critical roles in hematopoiesis, myelodysplastic neoplasms, and leukemia. We previously demonstrated that Tifab enhances KMT2A::MLLT3-driven acute myeloid leukemia (AML) by either upregulating Hoxa9 or through ubiquitin-specific peptidase 15-mediated downregulation of p53 signaling. In this study, we show that Tifab deletion in KMT2A::MLLT3-induced AML impairs leukemia stem/progenitor cell (LSPC) engraftment, glucose uptake, and mitochondrial function. Gene set enrichment analysis reveals that Tifab deletion downregulates MYC, HOXA9/MEIS1, mTORC1 signaling, and genes involved in glycolysis and oxidative phosphorylation. By comparing genes upregulated in TIFAB-overexpressing LSPCs with those downregulated upon Tifab deletion, we identify hepatocyte nuclear factor 4 alpha (Hnf4a) as a key TIFAB target, regulated through the inhibition of NF-κB component RelB, which suppresses Hnf4a in leukemia cells. HNF4A, a nuclear receptor involved in organ development, metabolism, and tumorigenesis, rescues the metabolic defects caused by Tifab deletion and enhances leukemia cell engraftment. Conversely, Hnf4a knockdown attenuates TIFAB-mediated enhancement of LSPC function. These findings highlight the critical role of the TIFAB-HNF4A axis in KMT2A::MLLT3-induced AML and uncover a novel regulator in leukemia biology.

Small Molecule Modulators of AMP-Activated Protein Kinase (AMPK) Activity and Their Potential in Cancer Therapy

AMP-activated protein kinase (AMPK) is a central mediator of cellular metabolism and is activated in direct response to low ATP levels. Activated AMPK inhibits anabolic pathways and promotes catabolic activities that generate ATP through the phosphorylation of multiple target substrates. AMPK is a therapeutic target for activation in several chronic metabolic diseases, and there is increasing interest in targeting AMPK activity in cancer where it can act as a tumor suppressor or conversely it can support cancer cell survival. Small molecule AMPK activators and inhibitors have demonstrated some success in suppressing cancer growth, survival, and drug resistance in preclinical cancer models. In this perspective, we summarize the role of AMPK in cancer and drug resistance, the influence of the tumor microenvironment on AMPK activity, and AMPK activator and inhibitor development. In addition, we discuss the potential importance of isoform-selective targeting of AMPK and approaches for selective AMPK targeting in cancer.

Eugenol Promotes Apoptosis in Leukemia Cells via Targeting the Mitochondrial Biogenesis PPRC1 Gene

Acute myeloid leukemia (AML) is a highly heterogenous and aggressive myeloid neoplasm. To sustain growth and survival, AML cells, like other neoplasms, require energy. This process is orchestrated by mitochondria and is under the control of several genes, such as PPRC1 (PRC), a member of the PGC-1 family, which is a key player in the transcription control of mitochondrial biogenesis. We have shown here that eugenol inhibits cell growth and promotes apoptosis through the mitochondrial pathway in AML cell lines as well as in cells from AML patients but not in cells from healthy donors. Similar effects were also observed on cytarabine-resistant AML cells. Interestingly, eugenol downregulated PPRC1 at both the protein and mRNA levels and reduced mitochondrial membrane potential in AML cells. We have also shown that PPRC1 expression is higher in cancer cells from blood, breast, and other types of cancer relative to normal cells, and high PPRC1 levels correlate significantly with short overall survival (OS). In addition, PPRC1 gene mutations significantly correlate with short OS and/or disease-free survival in several cancers. PPRC1 mutations also correlated significantly with poor OS (p < 0.0001) when tested in a total of 23,456 cancer patients. These findings suggest an oncogenic role of PPRC1 in various types of cancer and the possible eugenol-targeting of this gene for the treatment of AML patients, especially those exhibiting resistance to cytarabine.

miR-182 promoter hypermethylation predicts the better outcome of AML patients treated with AZA + VEN in a real-world setting

BACKGROUND

5-Azacytidine (AZA) combined with the BCL2 inhibitor Venetoclax (VEN) is the standard treatment for elderly acute myeloid leukemia (AML) patients or those who are unfit for intensive chemotherapy (elderly or unfit AML). However, an effective and rapid predictive biomarker to predict treatment outcome remains elusive.

METHODS

miR-182 promoter methylation was measured in 94 AZA + VEN-treated elderly or unfit AML patients and 20 normal controls (NCs) samples. To determine whether miR-182 promoter methylation is a predictive marker of clinical outcomes in AZA + VEN-treated AML patients in a real-world setting, we analyzed and compared the complete remission (CR)/CR with incomplete hematologic recovery (CRi) rate, overall survival (OS), and leukemia free-survival (LFS) across different methylation groups: miR-182 promoter hypomethylation (median value < 20.21%) and hypermethylation (> 20.21%) in a retrospective study.

RESULTS

The average methylation frequency was markedly higher in 94 AZA + VEN-treated elderly or unfit AML patients than that in 20 NCs. However, some AML patients (11.7%) still presented low miR-182 promoter methylation (< 10%). The average time to obtain CR/CRi was shorter in AML patients with miR-182 promoter hypermethylation than AML with hypomethylation. Moreover, the median OS and LFS were longer in AML patients with miR-182 promoter hypermethylation than AML with hypomethylation. Finally, the area under the curve (AUC) for 1-year mortality was 0.831, for 2-year was 0.788, and for 3-year was 0.800.

CONCLUSIONS

AML patients with miR-182 promoter hypermethylation have better outcomes. miR-182 promoter methylation is a predictive biomarker for AZA + VEN-treated AML patients.

Nuclear Control of Mitochondrial Homeostasis and Venetoclax Efficacy in AML via COX4I1

Cell signaling pathways are enriched for biological processes crucial for cellular communication, response to external stimuli, and metabolism. Here, a cell signaling-focused CRISPR screen identified cytochrome c oxidase subunit 4 isoform 1 (COX4I1) as a novel vulnerability in acute myeloid leukemia (AML). Depletion of COX4I1 hindered leukemia cell proliferation and impacted in vivo AML progression. Mechanistically, loss of COX4I1 induced mitochondrial stress and ferroptosis, disrupting mitochondrial ultrastructure and oxidative phosphorylation. CRISPR gene tiling scans, coupled with mitochondrial proteomics, dissected critical regions within COX4I1 essential for leukemia cell survival, providing detailed insights into the mitochondrial Complex IV assembly network. Furthermore, COX4I1 depletion or pharmacological inhibition of Complex IV (using chlorpromazine) synergized with venetoclax, providing a promising avenue for improved leukemia therapy. This study highlights COX4I1, a nuclear encoded mitochondrial protein, as a critical mitochondrial checkpoint, offering insights into its functional significance and potential clinical implications in AML.

Dual-phase nanoscissors disrupt vasculature-breast cancer stem cell crosstalk for breast cancer treatment

Clinical treatment effects of breast cancer are heavily frustrated by the malignant crosstalk between tumor vasculature and breast cancer stem cells (BCSCs). This study introduces a two-phase therapeutic strategy targeting the interplay between tumor vasculature and BCSCs to overcome this challenge. Here, we an FLG/ZnPc nanoscissor, which combines mild photodynamic therapy (PDT) to generate reactive oxygen species (ROS) with vascular normalization therapy (VNT) to break the crosstalk between tumor vasculature and BCSCs. In the first phase, our approach breaks the vascular niche that supports BCSCs by restoring tumor vascular function and promoting ROS-induced BCSCs differentiation into less malignant forms, enhancing treatment sensitivity. The second phase employs high-impact photothermal therapy (PTT) to ablate tumor masses. This integrated "mild PDT-PTT" approach aims to reduce tumor growth and metastasis, offering a comprehensive strategy for effective breast cancer management.

ONC213: a novel strategy to resensitize resistant AML cells to venetoclax through induction of mitochondrial stress

BACKGROUND

Venetoclax + azacitidine is a frontline treatment for older adult acute myeloid leukemia (AML) patients and a salvage therapy for relapsed/refractory patients who have been treated with intensive chemotherapy. While this is an important treatment option, many patients fail to achieve complete remission and of those that do, majority relapse. Leukemia stem cells (LSCs) are believed to be responsible for AML relapse and can be targeted through oxidative phosphorylation reduction. We previously reported that ONC213 disrupts oxidative phosphorylation and decreases Mcl-1 protein, which play a key role in venetoclax resistance. Here we investigated the antileukemic activity and underlying molecular mechanism of the combination of ONC213 + venetoclax against AML cells.

METHODS

Flow cytometry was used to determine drug-induced apoptosis. Protein level changes were determined by western blot. An AML cell line-derived xenograft mouse model was used to determine the effects of ONC213 + venetoclax on survival. A patient-derived xenograft (PDX) mouse model was used to determine drug effects on CD45+/CD34+/CD38-/CD123 + cells. Colony formation assays were used to assess drug effects on AML progenitor cells. Mcl-1 and Bax/Bak knockdown and Mcl-1 overexpression were used to confirm their role in the mechanism of action. The effect of ONC213 + venetoclax on mitochondrial respiration was determined using a Seahorse bioanalyzer.

RESULTS

ONC213 + venetoclax synergistically kills AML cells, including those resistant to venetoclax alone as well as venetoclax + azacitidine. The combination significantly reduced colony formation capacity of primary AML progenitors compared to the control and either treatment alone. Further, the combination prolonged survival in an AML cell line-derived xenograft model and significantly decreased LSCs in an AML PDX model.

CONCLUSIONS

ONC213 can resensitize VEN + AZA-resistant AML cells to venetoclax therapy and target LSCs ex vivo and in vivo.

Zelenirstat Inhibits N-Myristoyltransferases to Disrupt Src Family Kinase Signaling and Oxidative Phosphorylation, Killing Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a hematologic malignancy with limited treatment options and a high likelihood of recurrence after chemotherapy. We studied N-myristoylation, the myristate modification of proteins linked to survival signaling and metabolism, as a potential therapeutic target for AML. N-myristoylation is catalyzed by two N-myristoyltransferases (NMT), NMT1 and NMT2, with varying expressions in AML cell lines and patient samples. We identified NMT2 expression as a marker for survival of patients with AML, and low NMT2 expression was associated with poor outcomes. We used the first-in-class pan-NMT inhibitor, zelenirstat, to investigate the role of N-myristoylation in AML. Zelenirstat effectively inhibits myristoylation in AML cell lines and patient samples, leading to degradation of Src family kinases, induction of endoplasmic reticulum stress, apoptosis, and cell death. Zelenirstat was well tolerated in vivo and reduced the leukemic burden in an ectopic AML cell line and in multiple orthotopic AML patient-derived xenograft models. The leukemia stem cell-enriched fractions of the hierarchical OCI-AML22 model were highly sensitive to myristoylation inhibition. Zelenirstat also impairs mitochondrial complex I and oxidative phosphorylation, which are critical for leukemia stem cell survival. These findings suggest that targeting N-myristoylation with zelenirstat represents a novel therapeutic approach for AML, with promise in patients with currently poor outcomes.

Lysosomal acid lipase A modulates leukemia stem cell response to venetoclax/tyrosine kinase inhibitor combination therapy in blast phase chronic myeloid leukemia

The treatment of blast phase chronic myeloid leukemia (bpCML) remains a challenge due, at least in part, to drug resistance of leukemia stem cells (LSC). Recent clinical evidence suggests that the BCL-2 inhibitor venetoclax in combination with ABL-targeting tyrosine kinase inhibitors can eradicate bpCML LSC. In this study, we employed preclinical models of bpCML to investigate the efficacy and underlying mechanism of LSC-targeting with combinations of venetoclax/tyrosine kinase inhibitors. Transcriptional analysis of LSC exposed to venetoclax and dasatinib revealed upregulation of genes involved in lysosomal biology, in particular lysosomal acid lipase A (LIPA), a regulator of free fatty acids. Metabolomic analysis confirmed increased levels of free fatty acids in response to treatment with venetoclax/dasatinib. Pretreatment of leukemia cells with bafilomycin, a specific lysosome inhibitor, or genetic perturbation of LIPA, resulted in increased sensitivity of leukemia cells to venetoclax/dasatinib, implicating LIPA in treatment resistance. Importantly, venetoclax/dasatinib treatment did not affect normal stem cell function, suggesting a leukemia-specific response. These results demonstrate that venetoclax/dasatinib is a LSC-selective regimen in bpCML and that disrupting LIPA and fatty acid transport enhances the response to venetoclax/ dasatinib when targeting LSC, providing a rationale for exploring lysosomal disruption as an adjunctive therapeutic strategy to prolong disease remission.

GPR68 supports AML cells through the calcium/calcineurin pro-survival pathway and confers chemoresistance by mediating glucose metabolic symbiosis

Accumulating evidence demonstrates that the "Warburg effect" that glycolysis is enhanced even in the presence of oxygen existed in hematopoietic malignancies, contributing to extracellular acidosis. G-protein coupled receptor 68 (GPR68), as a proton sensing GPCR responding to extracellular acidosis, is expected to play a critical role in hematopoietic malignancies. In the present study, we found that GPR68 was overexpressed in acute myeloid leukemia (AML) cells, and GPR68 deficiency impaired AML cell survival in vitro and cell engraftment in vivo. Mechanistic studies revealed that unlike GPR68 regulates Calpain1 in myelodysplastic syndromes (MDS) cells, GPR68 deficiency reduced cytosolic Ca2+ levels and calcineurin (CaN) activity in AML cells through an NFAT-independent mechanism. Moreover, the decreased Ca2+ levels disturbed cellular respiration (i.e., oxidative phosphorylation, OxPhos) by inhibiting isocitrate dehydrogenase (IDH) activity; this was more pronounced when BCL2 was inhibited simultaneously. Interestingly, GPR68 inhibition also decreased aerobic glycolysis in AML cells in a Ca2+-independent manner, suggesting that GPR68 mediated glucose metabolic symbiosis. As glucose metabolic symbiosis and the heterogeneous dependencies on aerobic glycolysis and cellular respiration tremendously impact chemosensitivity, the inhibition of GPR68 potentiated the tumoricidal effect of first-line chemotherapeutic agents, including BCL-2 inhibitors targeting OxPhos and cytarabine (Ara-C) targeting glycolysis. Consistent with these in vitro observations, higher levels of GPR68 were associated with inferior clinical outcomes in AML patients who received chemotherapies. In short, GPR68 drives the Ca2+/CaN pro-survival pathway and mediates glucose metabolic pathways in AML cells. Targeting GPR68 eradicates AML cells and alleviates chemoresistance, which could be exploited as a therapeutic target.

Clinical Pharmacology and Side Effects of Venetoclax in Hematologic Malignancies

Venetoclax is a first-in-class B-cell lymphoma/lymphoma-2 (BCL-2) inhibitor that induces apoptosis in malignant cells through the inhibition of BCL-2. The clinical response to venetoclax exhibits heterogeneity, and its sensitivity and resistance may be intricately linked to genetic expression. Pharmacokinetic studies following doses of venetoclax (ranging from 100 to 1200mg) revealed a time to maximum observed plasma concentration of 5-8 hours, with a maximum blood concentration of 1.58-3.89 μg/mL, and a 24-hour area under the concentration-time curve of 12.7-62.8 μg·h/mL. Population-based pharmacokinetic investigations highlighted that factors such as low-fat diet, race, and severe hepatic impairment play pivotal roles in influencing venetoclax dose selection. Being a substrate for CYP3A4, P-glycoprotein, and breast cancer resistance protein, venetoclax undergoes primary metabolism and clearance in the liver, displaying low accumulation in the body.The significance of dose modifications (a 50% decrease with moderate and a 75% reduction with strong CYP3A inhibitors) and a cautious two-hour interval when co-administered with P-glycoprotein inhibitors are highlighted by insights from clinical medication interaction studies. Moreover, an exposure-response relationship analysis indicates that venetoclax exposure significantly correlates not only with overall survival and total response rate but also with the occurrence of ≥ 3-grade neutropenia. In real-world studies, common or severe side effects of venetoclax include tumor lysis syndrome, myelosuppression, nausea, diarrhea, constipation, infection, autoimmune hemolytic anemia, and cardiac toxicity, among others. In this review, we summarize the current clinical pharmacology studies and side effects of venetoclax, which showed that the approved dosage of venetoclax is relatively wide, and the dosage for different hematologic populations can be streamlined in the future.

Mitochondrial-targeting strategies with homoharringtonine: A novel approach for chemoresistant rectal cancer

5-Fluorouracil (5-FU) resistance poses a significant challenge in the treatment of rectal cancer, driving the need for novel therapeutic strategies. In this study, we established 5-FU-resistant rectal cancer cell lines (SW837-r, SNU-C1-r) and identified homoharringtonine (HHT) as a potent and selective anticancer agent through high-throughput drug screening of 291 compounds. HHT displayed the highest selective drug sensitivity score (sDSS), showing strong activity against resistant cells while sparing normal rectal epithelial cells. Further investigations revealed that 5-FU-resistant cells exhibited enhanced mitochondrial biogenesis and function compared to normal cells, and HHT exerted its cytotoxic effects by targeting mitochondrial respiration. HHT significantly reduced oxygen consumption rate (OCR), mitochondrial complex I activity, and ATP production in resistant cells, with mitochondrial respiration-deficient ρ0 cells showing reduced sensitivity to HHT. In vivo, HHT alone reduced tumor growth by 60 % in the resistant xenograft model. In the sensitive xenograft model, combination therapy with 5-FU achieved an 85 % reduction in tumor volume compared to controls, with tumors in the combination group displaying minimal regrowth. These results demonstrate that HHT effectively targets mitochondrial function in resistant rectal cancer cells and, in combination with 5-FU, offers synergistic antitumor effects and prolonged tumor suppression. The favorable safety profile of HHT further highlights its potential as a promising therapeutic agent for overcoming 5-FU resistance in rectal cancer.

The BIM deletion polymorphism potentiates the survival of leukemia stem and progenitor cells and impairs response to targeted therapies

One sixth of human cancers harbor pathogenic germline variants, but few studies have established their functional contribution to cancer outcomes. Here, we developed a humanized mouse model harboring a common East Asian polymorphism, the BIM deletion polymorphism (BDP), which confers resistance to oncogenic kinase inhibitors through generation of non-apoptotic splice isoforms. However, despite its clear role in mediating bulk resistance in patients, the BDP's role in cancer stem and progenitor cells, which initiate disease and possess altered BCL-2 rheostats compared to differentiated tumor cells, remains unknown. To study the role of the BDP in leukemia initiation, we crossed the BDP mouse into a chronic myeloid leukemia (CML) model. We found that the BDP greatly enhanced the fitness of CML cells with a three-fold greater competitive advantage, leading to more aggressive disease. The BDP conferred almost complete resistance to cell death induced by imatinib in CML stem and progenitor cells (LSPCs). Using BH3 profiling, we identified a novel therapeutic vulnerability of BDP LSPCs to MCL-1 antagonists, which we confirmed in primary human LSPCs, and in vivo. Our findings demonstrate the impact of human polymorphisms on the survival of LSPCs and highlight their potential as companion diagnostics for tailored therapies.

AOH1996 targets mitochondrial dynamics and metabolism in leukemic stem cells via mitochondrial PCNA inhibition

Cytoplasmic proliferating cell nuclear antigen (PCNA) is highly expressed in acute myeloid leukemia (AML) cells, supporting oxidative metabolism and leukemia stem cell (LSC) growth. We report on AOH1996 (AOH), an oral compound targeting cancer-associated PCNA, which shows significant antileukemic activity. AOH inhibited growth in AML cell lines and primary CD34 + CD38 - blasts (LSC-enriched) in vitro while sparing normal hematopoietic stem cells (HSCs). In vivo, AOH-treated mice demonstrated prolonged survival compared to controls (50 vs. 35 days; p < 0.0001) with reduced LSC burden, as shown in secondary transplants (42 vs. 30 days, p < 0.0001). Mechanistically, AOH disrupted mitochondrial PCNA's binding to the OPA1 protein, enhancing OPA1's interaction with its E3 ligase, MARCH5, which led to OPA1 degradation. This process reduced mitochondrial length, fatty acid oxidation (FAO), and oxidative phosphorylation (OXPHOS), thereby inhibiting LSC expansion. The addition of venetoclax (VEN), an FDA-approved Bcl-2 inhibitor, further enhanced AOH's effects, reducing mitochondrial length, FAO, and OXPHOS while improving survival in AML models. While VEN is approved for AML, AOH is under clinical investigation for solid tumors, and our findings support its broader therapeutic potential.

Targeting mitochondrial RNAs enhances the efficacy of the DNA-demethylating agents

Hypomethylating agents (HMAs) such as azacytidine and decitabine are FDA-approved chemotherapy drugs for hematologic malignancy. By inhibiting DNA methyltransferases, HMAs reactivate tumor suppressor genes (TSGs) and endogenous double-stranded RNAs (dsRNAs) that limit tumor growth and trigger apoptosis via viral mimicry. Yet, HMAs show limited effects in many solid tumors despite the strong induction of TSGs and dsRNAs. Here we show that targeting mitochondrial RNAs (mtRNAs) can enhance the HMA-mediated cell death in lung adenocarcinoma cells. We find that HMA treatment accompanies increased mtRNA levels and subsequent enhancement of metabolic activity, resulting in higher ATP production. Compromising the mitochondrial function by downregulating mature mtRNA expression increased cell death by HMAs. We further perform a CRISPR screening on mtRNA processing factors and find that mtRNA polymerase (POLRMT) and ElaC Ribonuclease Z 2 (ELAC2) depleted cells show increased sensitivity to HMAs by suppressing decitabine-triggered enhancement of ATP production. Moreover, we show that a small molecular inhibitor of POLRMT compromises the metabolic activity and synergistically enhances the cytotoxicity of HMAs. Our study unveils the insensitivity to HMAs through the elevation of mtRNAs and suggests mtRNA regulatory factors as potential synergistic targets to improve the therapeutic benefit of HMAs.

Unlocking the Heterogeneity in Acute Leukaemia: Dissection of Clonal Architecture and Metabolic Properties for Clinical Interventions

Genetic studies of haematological cancers have pointed out the heterogeneity of leukaemia in its different subpopulations, with distinct mutations and characteristics, impacting the treatment response. Next-generation sequencing (NGS) and genome-wide analyses, as well as single-cell technologies, have offered unprecedented insights into the clonal heterogeneity within the same tumour. A key component of this heterogeneity that remains unexplored is the intracellular metabolome, a dynamic network that determines cell functions, signalling, epigenome regulation, immunity and inflammation. Understanding the metabolic diversities among cancer cells and their surrounding environments is therefore essential in unravelling the complexities of leukaemia and improving therapeutic strategies. Here, we describe the currently available methodologies and approaches to addressing the dynamic heterogeneity of leukaemia progression. In the second section, we focus on metabolic leukaemic vulnerabilities in acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). Lastly, we provide a comprehensive overview of the most interesting clinical trials designed to target these metabolic dependencies, highlighting their potential to advance therapeutic strategies in leukaemia treatment. The integration of multi-omics data for cancer identification with the metabolic states of tumour cells will enable a comprehensive "micro-to-macro" approach for the refinement of clinical practices and delivery of personalised therapies.

Targeting Fatty Acid Metabolism Abrogates the Differentiation Blockade in Preleukemic Cells

Metabolism plays a key role in the maintenance of normal hematopoietic stem cells (HSC) and in the development of leukemia. A better understanding of the metabolic characteristics and dependencies of preleukemic cells could help identify potential therapeutic targets to prevent leukemic transformation. As AML1-ETO, one of the most frequent fusion proteins in acute myeloid leukemia that is encoded by a RUNX1::RUNX1T1 fusion gene, is capable of generating preleukemic clones, in this study, we used a conditional Runx1::Runx1t1 knockin mouse model to evaluate preleukemic cell metabolism. AML1-ETO expression resulted in impaired hematopoietic reconstitution and increased self-renewal ability. Oxidative phosphorylation and glycolysis decreased significantly in these preleukemic cells accompanied by increased HSC quiescence and reduced cell cycling. Furthermore, HSCs expressing AML1-ETO exhibited an increased requirement for fatty acids through metabolic flux. Dietary lipid deprivation or loss of the fatty acid transporter FATP3 by targeted deletion using CRISPR/Cas9 partially restored differentiation. These findings reveal the unique metabolic profile of preleukemic cells and propose FATP3 as a potential target for disrupting leukemogenesis. Significance: Fatty acid metabolism is required for maintenance of preleukemic cells but dispensable for normal hematopoiesis, indicating that dietary lipid deprivation or inhibiting fatty acid uptake may serve as potential strategies to prevent leukemogenesis.

Targeting pivotal amino acids metabolism for treatment of leukemia

Metabolic reprogramming is a crucial characteristic of cancer, allowing cancer cells to acquire metabolic properties that support their survival, immune evasion, and uncontrolled proliferation. Consequently, targeting cancer metabolism has become an essential therapeutic strategy. Abnormal amino acid metabolism is not only a key aspect of metabolic reprogramming but also plays a significant role in chemotherapy resistance and immune evasion, particularly in leukemia. Changes in amino acid metabolism in tumor cells are typically driven by a combination of signaling pathways and transcription factors. Current approaches to targeting amino acid metabolism in leukemia include inhibiting amino acid transporters, blocking amino acid biosynthesis, and depleting specific amino acids to induce apoptosis in leukemic cells. Different types of leukemic cells rely on the exogenous supply of specific amino acids, such as asparagine, glutamine, arginine, and tryptophan. Therefore, disrupting the supply of these amino acids may represent a vulnerability in leukemia. This review focuses on the pivotal role of amino acids in leukemia metabolism, their impact on leukemic stem cells, and their therapeutic potential.