Blockade Of Differentiation Research Articles

Identification of isoquinolinone DHODH inhibitor isosteres

DHODH inhibition represents an attractive approach to overcome differentiation blockade for the treatment of AML. In a previous communication, we described our efforts leading to the discovery of compound 3 (JNJ-74856665), an orally bioavailable, potent, and selective DHODH inhibitor for clinical development. Guided by the co-crystal structures bound to human DHODH, other fused six-membered constructs were explored as isosteric replacements of the isoquinolinone central core. The correct positioning of the nitrogen in these core systems proved to be essential in modulating potency. Herein is described the synthesis of these complexly functionalized cores and their profiling, leading to DHODH inhibitors that possess favorable properties suitable for further development.

Targeting Fatty Acid Metabolism Abrogates the Differentiation Blockade in Pre-leukemic Cells.

Metabolism plays a key role in the maintenance of normal hematopoietic stem cells (HSCs) and in the development of leukemia. A better understanding of the metabolic characteristics and dependencies of pre-leukemic 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 pre-leukemic clones, here we used a conditional Runx1::Runx1t1 knock-in mouse model to evaluate pre-leukemic cell metabolism. AML1-ETO expression resulted in impaired hematopoietic reconstitution and increased self-renewal ability. Oxidative phosphorylation and glycolysis decreased significantly in these pre-leukemic 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 pre-leukemic cells and propose FATP3 as a potential target for disrupting leukemogenesis.

Impact of p53-associated acute myeloid leukemia hallmarks on metabolism and the immune environment.

Acute myeloid leukemia (AML), an aggressive malignancy of hematopoietic stem cells, is characterized by the blockade of cell differentiation, uncontrolled proliferation, and cell expansion that impairs healthy hematopoiesis and results in pancytopenia and susceptibility to infections. Several genetic and chromosomal aberrations play a role in AML and influence patient outcomes. TP53 is a key tumor suppressor gene involved in a variety of cell features, such as cell-cycle regulation, genome stability, proliferation, differentiation, stem-cell homeostasis, apoptosis, metabolism, senescence, and the repair of DNA damage in response to cellular stress. In AML, TP53 alterations occur in 5%-12% of de novo AML cases. These mutations form an important molecular subgroup, and patients with these mutations have the worst prognosis and shortest overall survival among patients with AML, even when treated with aggressive chemotherapy and allogeneic stem cell transplant. The frequency of TP53-mutations increases in relapsed and recurrent AML and is associated with chemoresistance. Progress in AML genetics and biology has brought the novel therapies, however, the clinical benefit of these agents for patients whose disease is driven by TP53 mutations remains largely unexplored. This review focuses on the molecular characteristics of TP53-mutated disease; the impact of TP53 on selected hallmarks of leukemia, particularly metabolic rewiring and immune evasion, the clinical importance of TP53 mutations; and the current progress in the development of preclinical and clinical therapeutic strategies to treat TP53-mutated disease.

Comprehensive analysis of the REST transcription factor regulatory networks in IDH mutant and IDH wild-type glioma cell lines and tumors

The RE1-silencing transcription factor (REST) acts either as a repressor or activator of transcription depending on the genomic and cellular context. REST is a key player in brain cell differentiation by inducing chromatin modifications, including DNA methylation, in a proximity of its binding sites. Its dysfunction may contribute to oncogenesis. Mutations in IDH1/2 significantly change the epigenome contributing to blockade of cell differentiation and glioma development. We aimed at defining how REST modulates gene activation and repression in the context of the IDH mutation-related phenotype in gliomas. We studied the effects of REST knockdown, genome wide occurrence of REST binding sites, and DNA methylation of REST motifs in IDH wild type and IDH mutant gliomas. We found that REST target genes, REST binding patterns, and TF motif occurrence proximal to REST binding sites differed in IDH wild-type and mutant gliomas. Among differentially expressed REST targets were genes involved in glial cell differentiation and extracellular matrix organization, some of which were differentially methylated at promoters or gene bodies. REST knockdown differently impacted invasion of the parental or IDH1 mutant glioma cells. The canonical REST-repressed gene targets showed significant correlation with the GBM NPC-like cellular state. Interestingly, results of REST or KAISO silencing suggested the interplay between these TFs in regulation of REST-activated and repressed targets. The identified gene regulatory networks and putative REST cooperativity with other TFs, such as KAISO, show distinct REST target regulatory networks in IDH-WT and IDH-MUT gliomas, without concomitant DNA methylation changes. We conclude that REST could be an important therapeutic target in gliomas.

Induction of AML cell differentiation using HOXA9/DNA binding inhibitors as a potential therapeutic option for HOXA9-dependent AML.

The mainstay of acute myeloid leukemia (AML) treatment still relies on traditional chemotherapy, with a survival rate of approximately 30% for patients under 65 years of age and as low as 5% for those beyond. This unfavorable prognosis primarily stems from frequent relapses, resistance to chemotherapy, and limited approved targeted therapies for specific AML subtypes. Around 70% of all AML cases show overexpression of the transcription factor HOXA9, which is associated with a poor prognosis, increased chemoresistance, and higher relapse rates. However, direct targeting of HOXA9 in a clinical setting has not been achieved yet. The dysregulation caused by the leukemic HOXA9 transcription factor primarily results from its binding activity to DNA, leading to differentiation blockade. Our previous investigations have identified two HOXA9/DNA binding competitors, namely DB1055 and DB818. We assessed their antileukemic effects in comparison to HOXA9 knockdown or cytarabine treatment. Using human AML cell models, DB1055 and DB818 induced in vitro cell growth reduction, death, differentiation, and common transcriptomic deregulation but did not impact human CD34+ bone marrow cells. Furthermore, DB1055 and DB818 exhibited potent antileukemic activities in a human THP-1 AML in vivo model, leading to the differentiation of monocytes into macrophages. In vitro assays also demonstrated the efficacy of DB1055 and DB818 against AML blasts from patients, with DB1055 successfully reducing leukemia burden in patient-derived xenografts in NSG immunodeficient mice. Our findings indicate that inhibiting HOXA9/DNA interaction using DNA ligands may offer a novel differentiation therapy for the future treatment of AML patients dependent on HOXA9.

Neurofibromin 1 controls metabolic balance and Notch-dependent quiescence of murine juvenile myogenic progenitors

Patients affected by neurofibromatosis type 1 (NF1) frequently show muscle weakness with unknown etiology. Here we show that, in mice, Neurofibromin 1 (Nf1) is not required in muscle fibers, but specifically in early postnatal myogenic progenitors (MPs), where Nf1 loss led to cell cycle exit and differentiation blockade, depleting the MP pool resulting in reduced myonuclear accretion as well as reduced muscle stem cell numbers. This was caused by precocious induction of stem cell quiescence coupled to metabolic reprogramming of MPs impinging on glycolytic shutdown, which was conserved in muscle fibers. We show that a Mek/Erk/NOS pathway hypersensitizes Nf1-deficient MPs to Notch signaling, consequently, early postnatal Notch pathway inhibition ameliorated premature quiescence, metabolic reprogramming and muscle growth. This reveals an unexpected role of Ras/Mek/Erk signaling supporting postnatal MP quiescence in concert with Notch signaling, which is controlled by Nf1 safeguarding coordinated muscle growth and muscle stem cell pool establishment. Furthermore, our data suggest transmission of metabolic reprogramming across cellular differentiation, affecting fiber metabolism and function in NF1.

Along with PaO2/FiO2 ratio and lymphopenia, low HLA-DR monocytes are the only additional parameter that independently predicts the clinical course of undifferentiated SARS-CoV-2 patients in emergency departments.

Because one-third of patients deteriorate after their admission to the emergency department, assessing the prognosis of COVID-19 patients is of great importance. However, to date, only lymphopenia and the partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio have been reported as partly predictive of COVID-19-related further deterioration, and their association has not been evaluated. We asked whether other key biomarkers of SARS-CoV-2 immunologic defects-increase in circulating immature granulocytes, loss of monocyte HLA-DR (mHLA-DR) expression, and monocyte differentiation blockade-could also predict further COVID-19 deterioration. A series of 284 consecutive COVID-19 patients, with the sole inclusion criterion of being an adult, were prospectively enrolled at emergency department admission (day 0) of 2 different hospitals: 1 for the exploratory cohort (180 patients) and 1 for the confirmatory cohort (104 patients). Deterioration was assessed over the next 7 days. Neither increased immature granulocyte levels nor monocyte differentiation blockade predicted patient worsening. Among more than 30 clinical, biological, and radiological parameters, the value of decreased P/F ratio and lymphopenia for prediction of further COVID-19 deterioration was strongly confirmed, and the loss of mHLA-DR was the only additional independent marker. Combined together in a simple OxyLymphoMono score, the 3 variables perfectly predicted patients who did not worsen and correctly predicted worsening in 59% of cases. By highlighting lymphocyte and monocyte defects as preceding COVID-19 deterioration, these results point on early immunosuppression in COVID-19 deterioration. Combining P/F ratio, lymphopenia, and loss of mHLA-DR together in a simple and robust score could offer a pragmatic method for COVID-19 patient stratification.

PGK1 Represents a Therapeutic Target for Pediatric Acute Myeloid Leukemia Via Regulating c-Myc/SLC7A5/mTOR Pathway

Acute myeloid leukemia (AML) is a clonal disorder of hematopoietic stem and progenitor cells characterized by abnormal growth, differentiation blockade, and accumulation of immature myeloblasts, which accounts for 15-20% of pediatric leukemia. Emerging literature has shown that metabolism disorder and their related pathways, play pivotal roles in leukemogenesis and disease progression. Phosphoglycerate kinase 1 (PGK1), an essential enzyme in glycolysis pathway, has been demonstrated to be up-regulated in several malignancies, and was related with tumor stage and poor prognosis. This study aimed to investigate the correlation between PGK1 expression and tumorigenesis of AML, explore the possible underlying mechanism as well as provide a potential therapeutic target for pediatric AML. The research included 64 AML patients and 10 healthy donors recruited from July, 2012 to June, 2020 in Children's Hospital of Soochow University. Expression of PGK1 mRNA in bone marrow of newly-diagnosed AML patients was higher than normal group (p<0.001). Based on median expression of PGK1, 64 patients were divided into PGK1high group (n=32) and PGK1low group (n=32). Patients in PGK1high group had lower complete remission (CR) rate after first course of chemotherapy (65.6% vs 75.0%, p=0.027), overall survival (OS) (53.1%±8.8% vs 84.4%±6.4%, p=0.004) and relapse-free survival (RFS)(63.5%±10.4% vs 90.1%±5.4%, p=0.018). PGK1-knockdown cell lines were constructed to figure out the correlation between PGK1 expression and AML development in vitro. Knockdown of PGK1 inhibited the proliferation, suppressed colony formation and promoted apoptosis of AML cells. In addition, PGK1KD AML cells became more sensitive to Cytarabine (Ara-C) and daunorubicin (DNR). AML model was established by injecting PGK1KD P388-D1 cells of BALB/c mice via tail veins. The results indicated that growth of PGK1KD cells in vivo was significantly suppressed compared to negative control group. Moreover, the median survival time of PGK1 KD group was shorter (10 days vs 13 days, p=0.035). NG52, a newly reported small molecule kinase inhibitor of PGK1, could block glycolysis pathway by suppressing the kinase activity of PGK1. NG52 promoted MV4-11 and Kasumi-1 apoptosis in a dose-dependant manner, and showed synergism with Ara-C and DNR in MV4-11 and Kasumi-1. To identify downstream targets of PGK1, RNA-sequencing analysis was performed in PGK1 KD cell lines. SLC7A5 was found to be the most significant down-regulated gene of differentially expressed genes (DEGs). Meanwhile, c-Myc, p-S6 and p-4EBP1 expression were reduced in PGK1 KD cell lines, indicating that c-Myc/SLC7A5/mTOR pathway was suppressed in PGK1 KD AML cells. We subsequently established SLC7A5 KD cells. Inhibition of proliferation and increased apoptosis was found in SLC7A5 KD cells, which was consistent with the results in PGK1 KD cells. Expression of c-Myc and activation of mTOR pathway were observably decreased in SLC7A5 KD cells, which supported the hypothesis above. We found that SLC7A5 expression level was also higher in AML patients than in healthy donors. In conclusion, our study indicated that PGK1 is a molecular biomarker of poor prognosis and a potential therapeutic target of pediatric AML. Inhibition of PGK1 suppressed progression of AML by regulating c-Myc/SLC7A5/mTOR pathway, providing a promising intervention for AML precision medicine.

Iadademstat and Gilteritinib for the Treatment of FLT3-Mutated Relapsed/Refractory Acute Myeloid Leukemia: The Frida Study

Background: Frontline and relapsed /refractory (R/R) acute myeloid leukemia (AML) patients carrying fms-related tyrosine kinase 3 [FLT3]-mutations (FLT3 mut+) benefit from FLT3 inhibitors (FLT3i) that have emerged as active therapeutic agents for this subset of AML encompassing up to 30-40% of all AML cases. The FLT3i gilteritinib, as monotherapy for R/R AML pts, has improved outcomes but the duration of remission achieved is transient and often brief. The Phase 3 randomized ADMIRAL trial of gilteritinib demonstrated a 20% CR rate and 2.8 months event-free-survival (EFS) (Perl, et al., NEJM 2019). The development of new targeted agents which synergize with FLT3 inhibitors, and ideally also inhibit the emergence of resistance, is therefore a major medical need in AML. Iadademstat (iada/ORY-1001) is a specific, oral, potent, covalent inhibitor of the epigenetic Lysine-Specific Demethylase 1 (LSD1/KDMA1) enzyme. Epigenetic dysregulation is a hallmark of AML. Up to 70% of recurring mutations in AML patients target epigenetic regulators of gene expression, resulting in myeloid differentiation blockade and enhanced leukemic stem cell renewal, underscoring the potential of epigenetic therapies to change the natural history of the disease. Preclinically, iada produces striking synergy with FLT3is, particularly gilteritinib in FLT3 wild-type and FLT3 mut+ AML cells and in derived cell lines resistant to venetoclax, azacitidine and other FLT3is (Sacilotto et al., 2022 Eur J. of Cancer 174S1). The novel MOAs generating this synergy in combinations include activation of a pro-differentiating epigenetic transcriptional program with simultaneous suppression of MYC-driven target genes (Yashar, et al. 2023, Mol. Cancer Res). The recently completed Phase 2 study of iada in combination with azacitidine (ALICE) produced a high rate of composite remission, including complete remission (CR) and CR with incomplete count recovery (CRi) (mostly MRD negative), as well as durable responses, in treatment naïve, unfit AML patients (pts), without exacerbating the toxicity profile of azacitidine (Salamero et al., 2022, Blood S1). The FRIDA study (NCT05546580) aims to establish the safety, tolerability, and the recommended phase 2 dose (RP2D) of the combination of iada plus gilteritinib in FLT3 mut+ R/R AML. Methods: Adult pts with body weight ≥50 Kg and ECOG 0-2, with FLT3 mut+ R/R AML, after no more than 2 prior lines of therapy, are enrolling. Certain patients with prior exposure to FLT3is including gilteritinib may be eligible. Up to 18 pts, in a 3+3 escalation phase, will receive iada at doses of 75 to 150 ug, orally, in 5 days ON - 2 days OFF schedule, with continuous gilteritinib, at 120 mg/day orally. In the expansion phase, up to 14 pts at the selected safe and pharmacologically active dose/s (determined based on all available data from escalation pts including PK, target engagement (TE), safety, tolerability, and emerging activity) will be enrolled. Primary endpoints of the study are safety and RP2D determination, based on the same 5 criteria outlined above. Bayesian posterior probability efficacy monitoring will be performed periodically for each dose cohort in the expansion phase. Bayesian efficacy futility and early stopping boundary will be applied during the monitoring. Posterior probability criterion (Prob (CR>0.3) ≥ 0.60) at the end of the study will warrant additional development. The safety of the combination treatment will also be continuously evaluated during expansion following a Bayesian design stopping rule.Secondary endpoints include overall survival, EFS, CR, CR/CR with partial hematologic recovery (CRh), overall response rates, time to response, duration of response, and transfusion rate. Exploratory endpoints include measurable residual disease and gene mutational analysis. At the time of the submission, FRIDA is enrolling a second dose level cohort in escalation phase and plans to have the 15 sites open to accrual in the US by the end of 2023. Additional sites will be added for a subsequent randomized controlled double-blinded FRIDA 2 study to assess the efficacy of the iada and gilteritinib combination in R/R FLT3 mut+ AML.

Stem cell-like reprogramming is required for leukemia-initiating activity in B-ALL.

B cell acute lymphoblastic leukemia (B-ALL) is a multistep disease characterized by the hierarchical acquisition of genetic alterations. However, the question of how a primary oncogene reprograms stem cell-like properties in committed B cells and leads to a preneoplastic population remains unclear. Here, we used the PAX5::ELN oncogenic model to demonstrate a causal link between the differentiation blockade, the self-renewal, and the emergence of preleukemic stem cells (pre-LSCs). We show that PAX5::ELN disrupts the differentiation of preleukemic cells by enforcing the IL7r/JAK-STAT pathway. This disruption is associated with the induction of rare and quiescent pre-LSCs that sustain the leukemia-initiating activity, as assessed using the H2B-GFP model. Integration of transcriptomic and chromatin accessibility data reveals that those quiescent pre-LSCs lose B cell identity and reactivate an immature molecular program, reminiscent of human B-ALL chemo-resistant cells. Finally, our transcriptional regulatory network reveals the transcription factor EGR1 as a strong candidate to control quiescence/resistance of PAX5::ELN pre-LSCs as well as of blasts from human B-ALL.

The Combination of Lanraplenib, a Selective SYK Inhibitor, and Gilteritinib, a FLT3 Inhibitor, Targets Aberrant Proliferation and Differentiation Blockade in Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is an aggressive disease characterized by uncontrolled clonal proliferation of poorly differentiated myeloid progenitor cells in the bone marrow and blood. Deregulated spleen tyrosine kinase (SYK) impairs myeloid differentiation and has been implicated in the pathogenesis of AML driven by FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutation (FLT3-ITD). While SYK is rarely mutated, it is highly activated in FLT3-ITD-mutated AML and directly phosphorylates FLT3-ITD, resulting in aberrant expression of multiple oncogenic pathways. Lanraplenib (LANRA) is a selective, next-generation, SYK inhibitor that has shown favorable PK, PD, and safety in healthy volunteers and patients with autoimmune diseases. LANRA is currently being evaluated in combination with gilteritinib, a FLT3 inhibitor, in patients with relapsed or refractory (R/R) FLT3-mutated AML (NCT05028751). By jointly inhibiting the leukemogenic network created by SYK and mutant FLT3, LANRA and gilteritinib potentially provide a new treatment regimen in a patient population with few treatment options. Method: AML cell viability in response to LANRA, gilteritinib or their combination was assessed by CellTiter Glo (CTG) at 5 days. Apoptosis was evaluated by measuring Annexin V and propidium iodide staining by flow cytometry. Myeloid differentiation was assessed by flow cytometry using CD11b and CD14 cell surface markers and/or immunohistochemistry. In addition, RNA-seq was performed to evaluate differential changes in gene expression in response to LANRA. Gene set enrichment analysis (GSEA) was performed to evaluate perturbation in leukemogenic signaling pathways. In vivo studies were conducted using the MV4;11 cell line-derived xenograft model. LANRA was administered twice daily at a dose of 75 mg/kg via subcutaneous injections, either alone or in combination with gilteritinib at a dose of 2 mg/kg dosed once daily by oral gavage, for 28 days. Results: Treatment of FLT3-ITD mutated AML cells with LANRA results in dose- and time-dependent increase in myeloid differentiation and reductions in leukemic cell viability. RNA-seq analysis of MV4;11 cells revealed that LANRA abrogates multiple downstream FLT3-ITD leukemogenic signaling pathways including JAK/STAT3/5, MAPK, mTOR and OXPHOS. Combined pharmacologic inhibition of SYK with LANRA and FLT3-ITD with gilteritinib results in robust antileukemic effects in preclinical models of FLT3 ITD-driven AML. Additionally, the combination of LANRA and gilteritinib demonstrated increased differentiation and apoptosis induction in vitro. LANRA in combination with gilteritinib showed significant tumor growth inhibition compared to either single agent in a subcutaneous FLT3-ITD AML cell line-derived xenograft mouse model. In line with these observations, a retrospective analysis of bone marrow-engrafted AML cells from a disseminated FLT3-ITD AML patient-derived xenograft mouse model showed evidence of increased myeloid differentiation and inhibition of cell proliferation. Conclusion: In preclinical models, LANRA demonstrates compelling anti-leukemic activity in combination with gilteritinib. By jointly targeting hyperproliferation and differentiation blockade, LANRA and gilteritinib may provide a new therapeutic approach that can be exploited in AML. Additionally, LANRA disrupts downstream signaling of key pathways often associated with resistance to gilteritinib, providing additional mechanistic support for continued testing of LANRA in combination with gilteritinib in FLT3-ITD-mutated AML patients. These studies helped motivate the ongoing clinical combination with gilteritinib in patients with (R/R) FLT3-mutated AML (NCT05028751).

Oligodendrocyte dynamics dictate cognitive performance outcomes of working memory training in mice

Previous work has shown that motor skill learning stimulates and requires generation of myelinating oligodendrocytes (OLs) from their precursor cells (OLPs) in the brains of adult mice. In the present study we ask whether OL production is also required for non-motor learning and cognition, using T-maze and radial-arm-maze tasks that tax spatial working memory. We find that maze training stimulates OLP proliferation and OL production in the medial prefrontal cortex (mPFC), anterior corpus callosum (genu), dorsal thalamus and hippocampal formation of adult male mice; myelin sheath formation is also stimulated in the genu. Genetic blockade of OL differentiation and neo-myelination in Myrf conditional-knockout mice strongly impairs training-induced improvements in maze performance. We find a strong positive correlation between the performance of individual wild type mice and the scale of OLP proliferation and OL generation during training, but not with the number or intensity of c-Fos+ neurons in their mPFC, underscoring the important role played by OL lineage cells in cognitive processing.

Prednisolone and rapamycin reduce the plasma cell gene signature and may improve AAV gene therapy in cynomolgus macaques

Adeno-associated virus (AAV) vector gene therapy is a promising approach to treat rare genetic diseases; however, an ongoing challenge is how to best modulate host immunity to improve transduction efficiency and therapeutic outcomes. This report presents two studies characterizing multiple prophylactic immunosuppression regimens in male cynomolgus macaques receiving an AAVrh10 gene therapy vector expressing human coagulation factor VIII (hFVIII). In study 1, no immunosuppression was compared with prednisolone, rapamycin (or sirolimus), rapamycin and cyclosporin A in combination, and cyclosporin A and azathioprine in combination. Prednisolone alone demonstrated higher mean peripheral blood hFVIII expression; however, this was not sustained upon taper. Anti-capsid and anti-hFVIII antibody responses were robust, and vector genomes and transgene mRNA levels were similar to no immunosuppression at necropsy. Study 2 compared no immunosuppression with prednisolone alone or in combination with rapamycin or methotrexate. The prednisolone/rapamycin group demonstrated an increase in mean hFVIII expression and a mean delay in anti-capsid IgG development until after rapamycin taper. Additionally, a significant reduction in the plasma cell gene signature was observed with prednisolone/rapamycin, suggesting that rapamycin’s tolerogenic effects may include plasma cell differentiation blockade. Immunosuppression with prednisolone and rapamycin in combination could improve therapeutic outcomes in AAV vector gene therapy.

Targeting cis-regulatory elements of FOXO family is a novel therapeutic strategy for induction of leukemia cell differentiation

Differentiation therapy has been proposed as a promising therapeutic strategy for acute myeloid leukemia (AML); thus, the development of more versatile methodologies that are applicable to a wide range of AML subtypes is desired. Although the FOXOs transcription factor represents a promising drug target for differentiation therapy, the efficacy of FOXO inhibitors is limited in vivo. Here, we show that pharmacological inhibition of a common cis-regulatory element of forkhead box O (FOXO) family members successfully induced cell differentiation in various AML cell lines. Through gene expression profiling and differentiation marker-based CRISPR/Cas9 screening, we identified TRIB1, a complement of the COP1 ubiquitin ligase complex, as a functional FOXO downstream gene maintaining an undifferentiated status. TRIB1 is direct target of FOXO3 and the FOXO-binding cis-regulatory element in the TRIB1 promoter, referred to as the FOXO-responsive element in the TRIB1 promoter (FRE-T), played a critical role in differentiation blockade. Thus, we designed a DNA-binding pharmacological inhibitor of the FOXO-FRE-T interface using pyrrole-imidazole polyamides (PIPs) that specifically bind to FRE-T (FRE-PIPs). The FRE-PIPs conjugated to chlorambucil (FRE-chb) inhibited transcription of TRIB1, causing differentiation in various AML cell lines. FRE-chb suppressed the formation of colonies derived from AML cell lines but not from normal counterparts. Administration of FRE-chb inhibited tumor progression in vivo without remarkable adverse effects. In conclusion, targeting cis-regulatory elements of the FOXO family is a promising therapeutic strategy that induces AML cell differentiation.

Molecular Features Associated with Response to Enasidenib Plus Azacitidine in Newly Diagnosed IDH2-Mutated Acute Myeloid Leukemia

IDH2 gene mutations, typically at residues R140 and R172, occur in 8–19% of patients with acute myeloid leukemia (AML). These mutations induce production of 2-hydroxyglutarate (2-HG), an oncometabolite that causes DNA and histone hypermethylation, and subsequent blockade of hematopoietic cell differentiation. In a phase 1b/2 trial (NCT02677922), combination therapy with azacitidine + enasidenib significantly improved overall response rate compared with azacitidine only therapy (74% vs 36%; P<0.001) in patients with newly diagnosed IDH2-mutated AML not eligible for intensive chemotherapy. We investigated the association between molecular features and clinical outcomes from that trial. In all, 101 patients were randomized to enasidenib + azacitidine (n=68) or azacitidine only (n=33); 74% of patients had IDH2-R140. Baseline 2-HG levels and IDH2 variant allele frequency (VAF) were similar between treatment arms and IDH2 variants and were not significantly different between clinical response categories. Significant 2-HG and IDH2 VAF reductions from baseline were observed with combination therapy compared with azacitidine only. Molecular profiling revealed SRSF2 preferentially co-mutated with IDH2-R140, and DNMT3A co-mutated with IDH2-R172. IDH2 VAF was reduced to <1% in 50% of patients who achieved CR with combination therapy (18/36) and azacitidine only (2/4). VAFs of genes in the DNA methylation, receptor-tyrosine-kinase, and RAS canonical pathways were reduced in patients achieving CR. Of note, combination therapy improved event-free survival in patients with RAS-pathway mutations, which have been associated with resistance to enasidenib monotherapy.

Critical role of MXRA7 in differentiation blockade in human acute promyelocytic leukemia cells

The biology of the matrix remodeling associated 7 (MXRA7) gene had been ill-defined. Inspired by public datasets and domestic findings concerning MXRA7, we hypothesized that MXRA7 might be involved in the pathogenesis of leukemia. This study aimed to investigate the role and effect of MXRA7 expression in acute promyelocytic leukemia (APL) cells differentiation and behavior. Bioinformatics of public datasets revealed MXRA7 mRNA was expressed highly in acute myeloid leukemia (AML), especially in APL. High expression of MXRA7 was associated with poor overall survival of AML patients. We confirmed MXRA7 expression was upregulated in APL patients and cell line. Knockdown or overexpression of MXRA7 did not affect the proliferation of NB4 cells directly. Knockdown of MXRA7 in NB4 cells promoted drug induced cell apoptosis, while overexpression of MXRA7 had no obvious influence on the drug induced cell apoptosis. Lowering MXRA7 protein levels in NB4 cells promoted ATRA-induced cell differentiation possibly through decreasing PML-RARα level and increasing PML and RARα levels. Correspondingly, overexpression of MXRA7 showed the consistent results. We also demonstrated that MXRA7 altered the expression of genes involved in leukemic cell differentiation and growth. Knockdown of MXRA7 upregulated the expression levels of C/EBPB, C/EBPD and UBE2L6, and downregulated the expression levels of KDM5A, CCND2 and SPARC. Moreover, knockdown of MXRA7 inhibited the malignancy of NB4 cells in NOD-SCID mice model. In conclusion, this study demonstrated that MXRA7 influences the pathogenesis of APL via regulation of the cell differentiation. The novel findings about the role of MXRA7 in leukemia not only shed lights on the biology of this gene, but also proposed this gene as a new target for APL treatment.

A novel mesenchymal stem cell-based regimen for acute myeloid leukemia differentiation therapy.

Currently the main treatment of acute myeloid leukemia (AML) is chemotherapy combining hematopoietic stem cell transplantation. However, the unbearable side effect of chemotherapy and the high risk of life-threatening infections and disease relapse following hematopoietic stem cell transplantation restrict its application in clinical practice. Thus, there is an urgent need to develop alternative therapeutic tactics with significant efficacy and attenuated adverse effects. Here, we revealed that umbilical cord-derived mesenchymal stem cells (UC-MSC) efficiently induced AML cell differentiation by shuttling the neutrophil elastase (NE)-packaged extracellular vesicles (EVs) into AML cells. Interestingly, the generation and release of NE-packaged EVs could be dramatically increased by vitamin D receptor (VDR) activation in UC-MSC. Chemical activation of VDR by using its agonist 1α,25-dihydroxyvitamin D3 efficiently enhanced the pro-differentiation capacity of UC-MSC and then alleviated malignant burden in AML mouse model. Based on these discoveries, to evade the risk of hypercalcemia, we synthetized and identified sw-22, a novel non-steroidal VDR agonist, which exerted a synergistic pro-differentiation function with UC-MSC on mitigating the progress of AML. Collectively, our findings provided a non-gene editing MSC-based therapeutic regimen to overcome the differentiation blockade in AML.

Apicidin confers promising therapeutic effect on acute myeloid leukemia cells via increasing QPCT expression

ABSTRACT Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by abnormal cell proliferation, apoptosis repression and myeloid differentiation blockade of hematopoietic stem/progenitor cells. Developing and identifying novel therapeutic agents to reverse the pathological processes of AML are of great significance. Here in this study, we found that a fungus-derived histone deacetylase inhibitor, Apicidin, presents promising therapeutic effect on AML by inhibiting cell proliferation, facilitating apoptosis and inducing myeloid differentiation of AML cells. Mechanistic investigation revealed that QPCT is identified as a potential downstream target of Apicidin, which exhibits significantly decreased expression in AML samples compared with the normal controls and is remarkably up-regulated in AML cells upon Apicidin management. Functional study and rescue assay demonstrated that QPCT depletion further promotes cell proliferation, inhibits apoptosis and impairs myeloid differentiation of AML cells, alleviating the anti-leukemic effect of Apicidin on AML. Our findings not only provide novel therapeutic target for AML, but also lay theoretical and experimental foundation for the clinical application of Apicidin in AML patients.

ICOS DNA methylation regulates melanoma cell-intrinsic ICOS expression, is associated with melanoma differentiation, prognosis, and predicts response to immune checkpoint blockade

BackgroundInducible T cell costimulator ICOS is an emerging target in immuno-oncology. The aim of this study was to investigate the epigenetic regulation of ICOS in melanoma by DNA methylation.MethodsWe comprehensively investigate ICOS DNA methylation of specific CpG sites and expression pattern within the melanoma microenvironment with regard to immune correlates, differentiation, clinical outcomes, and immune checkpoint blockade (ICB) response.ResultsOur study revealed a sequence-contextual CpG methylation pattern consistent with an epigenetically regulated gene. We found a cell type-specific methylation pattern and locus-specific correlations and associations of CpG methylation with ICOS mRNA expression, immune infiltration, melanoma differentiation, prognosis, and response to ICB. High ICOS mRNA expression was identified as a surrogate for enriched immune cell infiltration and was associated with favorable overall survival (OS) in non-ICB-treated patients and predicted response and a prolonged progression-free survival (PFS) following ICB therapy initiation. ICOS hypomethylation, however, significantly correlated with poor OS in non-ICB patients but predicted higher response and prolonged PFS and OS in ICB-treated patients. Moreover, we observed cytoplasmic and sporadically nuclear tumor cell-intrinsic ICOS protein expression. Tumor cell-intrinsic ICOS protein and mRNA expression was inducible by pharmacological demethylation with decitabine.ConclusionOur study identified ICOS DNA methylation and mRNA expression as promising prognostic and predictive biomarkers for immunotherapy in melanoma and points towards a hitherto undescribed role of ICOS in tumor cells.

Iadademstat in combination with gilteritinib for patients with mutated FLT3 relapsed/refractory acute myeloid leukemia.

TPS7075 Background: Epigenetic dysregulation is a hallmark of acute myeloid leukemia (AML) and is caused by recurrent translocations and/or mutations in chromatin regulators and transcription factors, resulting in myeloid differentiation blockade and leukemic stem cell renewal. Accordingly, about 70% of recurring mutations in AML patients (pts) target regulators of gene expression, underscoring the potential of epigenetic therapies to change the disease natural history. Iadademstat (iada/ORY-1001) is a specific, oral, potent, covalent inhibitor of the epigenetic Lysine-Specific Demethylase 1 (LSD1/KDMA1) enzyme. In preclinical and clinical studies iada decreased leukemic stem cell survival and induced macrophage/monocytic differentiation of blasts. ALICE, a Ph2 study of iada in combination with azacitidine (aza), showed high complete remission (CR/CRi) rates and durable responses in treatment naïve, unfit AML pts without exacerbating the toxicity profile of aza (Salamero et al., Oral at ASH 2022). Despite improvements in AML therapy, relapsed and refractory (R/R) cases are frequent and contribute to the death of more than 50% of pts, particularly in those subpopulations with higher risk genetics, the largest of which (up to 30-40% AML pts) harbors fms-like tyrosine kinase 3 mutations (FLT3mut+). Use of the FLT3 inhibitor (FLT3i) gilteritinib as monotherapy for R/R pts resulted in improved outcomes but the duration of remission achieved is transient and often brief (CR rate: 20%; EFS: 2.8 months) per the ADMIRAL Ph3 study (Perl, et al., NEJM 2019). Preclinically, iada has marked synergy with FLT3i, particularly gilteritinib, in FLT3 wild-type and FLT3 mut+ AML cells and in derived cell lines resistant to venetoclax, azacitidine and FLT3is. Methods: Adult pts with ECOG 0-2 and FLT3 mut+ R/R AML, after 1 or 2 prior lines of therapy, will be enrolled. In escalation (3+3), up to 18 pts will receive iada at 75 to 150 ug, orally, in 5 days ON-2 days OFF schedule, with gilteritinib SoC. Up to approximate 14 pts will be expanded from pharmacologically active dose/s (per Project OPTIMUS). Primary endpoints of the study are safety and RP2D determination. Bayesian posterior probability efficacy monitoring will be performed periodically for each dose cohort. Bayesian efficacy futility and early stopping boundary will be applied. Posterior probability criterion (Prob (CR > 0.3) ≥ 0.60) at the end of the study will warrant further research. Safety in expansion will be evaluated continuously with a Bayesian stopping rule. Secondary endpoints include OS, EFS, CR, CR/CRh, ORR, TTR, DoR, and transfusion rate. Exploratory endpoints include PK, PD, MRD and gene mutational analysis. The study will run in 15 US sites. Additional sites will be added for a subsequent Phase 2 randomized controlled double-blinded FRIDA 2 study to assess the efficacy of this combination in R/R FLT3 mut+ AML. Clinical trial information: NCT05546580 .