Chidamide, decitabine, cytarabine, aclarubicin, and granulocyte colony-stimulating factor (CDCAG) in patients with relapsed/refractory acute myeloid leukemia: a single-arm, phase 1/2 study

Chidamide induces cell cycle arrest via NR4A3/P21 axis upregulation to suppress relapsed and refractory acute myeloid leukemia

(1) Currently, the survival prognosis for patients with relapsed and refractory acute myeloid leukemia (R/R AML) is extremely poor. Therefore, the exploration of novel drugs is imperative to enhance the prognosis of patients with R/R AML. The therapeutic efficacy and mechanism of Chidamide, a novel epigenetic regulatory drug, in the treatment of R/R AML remain unclear.

METHODS

The mechanism of action of Chidamide has been explored in various AML cell lines through various methods such as cell apoptosis, cell cycle analysis, high-throughput transcriptome sequencing, gene silencing, and xenograft models.

RESULTS

Here, we have discovered that chidamide potently induces apoptosis, G0/G1 phase arrest, and mitochondrial membrane potential depolarization in R/R AML cells, encompassing both primary cells and cell lines. Through RNA-seq analysis, we further revealed that chidamide epigenetically regulates the upregulation of differentiation-related pathways while suppressing those associated with cell replication and cell cycle progression. Notably, our screening identified NR4A3 as a key suppressor gene whose upregulation by chidamide leads to P21-dependent cell cycle arrest in the G0/G1 phase.

CONCLUSIONS

We have discovered a novel epigenetic regulatory mechanism of chidamide in the treatment of relapsed and refractory acute myeloid leukemia (R/R AML).

Histone deacetylase inhibitors for leukemia treatment: current status and future directions

Leukemia remains a major therapeutic challenge in clinical oncology. Despite significant advancements in treatment modalities, leukemia remains a significant cause of morbidity and mortality worldwide, as the current conventional therapies are accompanied by life-limiting adverse effects and a high risk of disease relapse. Histone deacetylase inhibitors have emerged as a promising group of antineoplastic agents due to their ability to modulate gene expression epigenetically. In this review, we explore these agents, their mechanisms of action, pharmacokinetics, safety and clinical efficacy, monotherapy and combination therapy strategies, and clinical challenges associated with histone deacetylase inhibitors in leukemia treatment, along with the latest evidence and ongoing studies in the field. In addition, we discuss future directions to optimize the therapeutic potential of these agents.

Epigenetics: Mechanisms, potential roles, and therapeutic strategies in cancer progression

Mutations or abnormal expression of oncogenes and tumor suppressor genes are known to cause cancer. Recent studies have shown that epigenetic modifications are key drivers of cancer development and progression. Nevertheless, the mechanistic role of epigenetic dysregulation in the tumor microenvironment is not fully understood. Here, we reviewed the role of epigenetic modifications of cancer cells and non-cancer cells in the tumor microenvironment and recent research advances in cancer epigenetic drugs. In addition, we discussed the great potential of epigenetic combination therapies in the clinical treatment of cancer. However, there are still some challenges in the field of cancer epigenetics, such as epigenetic tumor heterogeneity, epigenetic drug heterogeneity, and crosstalk between epigenetics, proteomics, metabolomics, and other omics, which may be the focus and difficulty of cancer treatment in the future. In conclusion, epigenetic modifications in the tumor microenvironment are essential for future epigenetic drug development and the comprehensive treatment of cancer. Epigenetic combination therapy may be a novel strategy for the future clinical treatment of cancer.

Next-generation sequencing reveals relapse and leukemia-free survival risks in newly diagnosed acute myeloid leukemia treated with CAG regimen combined with decitabine

Background

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy whose prognosis is associated with several biomarkers. Decitabine, a deoxyribonucleic acid (DNA) methyltransferase (DNMT) inhibitor, combined with cytarabine, aclarubicin hydrochloride, and granulocyte colony-stimulating factor (DCAG), has been used in patients newly diagnosed with AML. This regimen has been especially used in older and fragile patients who are immunocompromised or have co-morbidities, as well as those with specific gene mutations. However, the integration of molecular risk stratification and treatment guidance for the DCAG regimen has not been well defined. Therefore, this study aimed to investigate the genetic mutations associated with AML and establish appropriate treatment strategies for patients newly diagnosed with AML.

Methods

This study analyzed the clinical data and genetic mutations based on next-generation sequencing (NGS) in 124 newly diagnosed patients with AML who received the DCAG regimen at the People's Liberation Army (PLA) General Hospital from January 2008 to August 2020. Factors associated with the cumulative incidence of relapse (CIR) and leukemia-free survival (LFS) in patients newly diagnosed with AML were analyzed.

Results

The most adverse prognosis of DCAG-treated patients was observed in those with FLT3-ITD, KIT, PTPN11, GATA2, or IDH1 mutations during univariable analysis, whereas PTPN11 mutation was solely significant in multivariable analysis, with an increased likelihood of CIR (P = 0.001) and reduced LFS duration (P = 0.077). Hyperleukocytosis was maintained as an independent risk factor for increased CIR risk (P = 0.044) and decreased LFS duration (P = 0.042) in multivariable analysis. In this study, we validated the risk classification of patients with AML receiving an epigenetic modifier-based induction regimen across a broad age range.

Conclusion

NGS demonstrated a dismal overall outcome in patients with the rare PTPN11 mutations, indicating the need for new therapies that target this high-risk subtype of AML. These results offer a potential molecular stratification and treatment guidance for patients with AML.

Chidamide, Decitabine, Cytarabine, Aclarubicin, and Granulocyte Colony-stimulating Factor Therapy for Patients with Relapsed/Refractory Acute Myeloid Leukemia: A Retrospective Study from a Single-Center

OBJECTIVE

Preclinical evidence and clinical trials have suggested synergistic effects of epigenetic modifiers in combination with cytotoxic agents for the treatment of leukemia. However, their efficacy in patients with relapsed/refractory acute myeloid leukemia (R/R AML) remains unclear.

METHODS

Clinical data of R/R AML patients who received a CDCAG regimen (chidamide, decitabine, cytarabine, aclarubicin, and granulocyte colony-stimulating factor) from July 1, 2018 to October 31, 2021 at our center were retrospectively assessed, and the safety and efficacy of the CDCAG regimen were evaluated. Patients were followed up until November 30, 2021, with a median follow-up of 21.6 months (95% CI: 10.0-33.2 months).

RESULTS

A total of 67 patients were enrolled. Two patients died within 3 weeks after the initiation, and therefore only 65 patients underwent the assement for clinical response and survival. It was found that 56.9% patients achieved complete remission with a median overall survival (OS) of 9.6 months. The median OS of responders was 25.9 months, while that of non-responders was 5.0 months (P<0.0001). Patients with gene mutations had a superior overall response rate (ORR) (80.4% vs. 45.5%, P=0.043) compared to those without gene mutations. The presence of DNA methyltransferase 3 A (DNMT3A), ten-eleven translocation-2 (TET2), and isocitrate dehydrogenase 1/2 (IDH1/2) mutations did not affect the response rate (88.2% vs. 68.9%, P=0.220) and reflected a better OS (not attained vs. 9.0 months, P=0.05). The most common non-hematologic adverse events were pulmonary infection (73.1%), followed by febrile neutropenia (23.9%) and sepsis (19.4%).

CONCLUSIONS

The CDCAG regimen was effective and well-tolerated in R/R AML patients, increasing the potential for allogeneic hematopoietic stem cell transplantation. Moreover, patients with DNMT3A, TET2, and IDH1/2 mutations might benefit from this regimen.

Venetoclax combined with hypomethylating agents and the CAG regimen in relapsed/refractory AML: a single-center clinical trial

Objective

This study aimed to evaluate the efficacy and safety of venetoclax in combination with hypomethylating agents and CAG (VEN-DCAG) regimens in patients with relapsed/refractory acute myeloid leukemia (R/R AML).

Methods

The treatment response was analyzed by retrospective methods in R/R AML patients treated with the VEN-DCAG regimen at our institution. This included, but was not limited to, CR/CRi (complete remission/complete remission with incomplete hematologic recovery) rate, measurable residual disease (MRD) negative rate, and overall survival (OS).

Results

20 patients with R/R AML were recruited, with a median age of 40 years (10-70), 11 of whom were male (55%), and a median follow-up of 10.4 months (0.7-21.8). The overall response rate (ORR) after receiving 1 course of VEN-DCAG was 90% (18/20), with 17 (85%) CR/CRi (10 MRD-CR), 1 (5%) PR, and 2 (10%) NR. Subsequently, 12 patients (7 MRD-CR, 4 MRD+CR, 1 NR) were treated with the VEN-DCAG regimen, and 3 MRD+CR patients turned negative, and 13 patients finally achieved MRD-CR. Among them, 7 patients were in the relapse group, all achieving CR/CRi (6 MRD-CR), and 13 patients in the refractory group, with 10 CR/CRi (7 MRD-CR). The ORR for patients in the relapse and refractory groups was 100% (7/7) and 84.6% (11/13), respectively. Further, all patients experienced adverse events (AEs) of varying degrees of severity, with hematologic AEs primarily consisting of myelosuppression, while non-hematologic AEs were more common in the form of fever, gastrointestinal distress, and infections. 11 patients were followed up with bridging allogeneic hematopoietic stem cell transplantation (allo-HSCT) therapy. At the last follow-up, 11 patients (7 MRD-CR, 4 MRD+CR) who received allo-HSCT, 1 (MRD+CR) died, and 9 patients (6 MRD-CR, 1 PR, 2 NR) who did not receive allo-HSCT, 5 (2 MRD-CR, 1 PR, 2 NR) died as well.

Conclusion

The VEN-DCAG regimen may be an effective treatment option for R/R AML patients, with high ORR and MRD negative remission rates in both the relapsed and refractory groups. It is recommend that patients should be bridged to allo-HSCT as soon as possible after induction to CR by the VEN-DCAG regimen, which can lead to a significant long-term survival benefit.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2300075985.

HDAC inhibitors: Promising agents for leukemia treatment

The essential role of epigenetic modification in the pathogenesis of a series of cancers have gradually been recognized. Histone deacetylase (HDACs), as well-known epigenetic modulators, are responsible for DNA repair, cell proliferation, differentiation, apoptosis and angiogenesis. Studies have shown that aberrant expression of HDACs is found in many cancer types. Thus, inhibition of HDACs has provided a promising therapeutic approach alternative for these patients. Since HDAC inhibitor (HDACi) vorinostat was first approved by the Food and Drug Administration (FDA) for treating cutaneous T-cell lymphoma (CTCL) in 2006, the combination of HDAC inhibitors with other molecules such as chemotherapeutic drugs has drawn much attention in current cancer treatment, especially in hematological malignancies therapy. Up to now, there have been more than twenty HDAC inhibitors investigated in clinic trials with five approvals being achieved. Indeed, Histone deacetylase inhibitors promote or enhance several different anticancer mechanisms and therefore are in evidence as potential antileukemia agents. In this review, we will focus on possible mechanisms by how HDAC inhibitors exert therapeutic benefit and their clinical utility in leukemia.

Preclinical development and evaluation of nanobody-based CD70-specific CAR T cells for the treatment of acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) treatment remains challenging. CD70 was reported as a promising AML-specific antigen. Preclinically, CAR T-cell with single-chain-variable fragment (scFv) or truncated CD27 targeting CD70 has been reported to treat AML. However, various disadvantages including spontaneous exhaustion, proteinase-mediated loss of functional receptors, and high immunogenicity, limited its further application to clinical settings. Alternatively, the single-variable domain on heavy chain (VHH), also known as nanobodies, with comparable binding ability and specificity, provides an optional solution.

METHOD

We generated CD70 knocked-out novel nanobody-based anti-CD70-CAR T-cells (nb70CAR-T) with two different VHHs for antigen detection. Next, we detected the CD70 expression on primary AML blasts by flow cytometry and associated the efficacy of nb70CAR-T with the target antigen density. Finally, epigenetic modulators were investigated to regulate the CD70 expression on AML cells to promote the functionality of nb70CAR-T.

RESULTS

Our nb70CAR-T exhibited expected tumoricidal functionality against CD70-expressed cell lines and primary AML blasts. However, CD70 expression in primary AML blasts was not consistently high and nb70CAR-T potently respond to an estimated 40.4% of AML patients when the CD70 expression level was over a threshold of 1.6 (MFI ratio). Epigenetic modulators, Decitabine and Chidamide can up-regulate CD70 expression on AML cells, enhancing the treatment efficacy of nb70CAR-T.

CONCLUSION

CD70 expression in AML blasts was not fully supportive of its role in AML targeted therapy as reported. The combinational use of Chidamide and Decitabine with nb70CAR-T could provide a new potential for the treatment of AML.

Disruption of mitochondrial oxidative phosphorylation by chidamide eradicates leukemic cells in AML

PURPOSE

Nowadays, the oxidative phosphorylation (OXPHOS) correlated with leukemogenesis and treatment response is extensive. Thus, exploration of novel approaches in disrupting OXPHOS in AML is urgently needed.

MATERIALS AND METHODS

Bioinformatical analysis of TCGA AML dataset was performed to identify the molecular signaling of OXPHOS. The OXPHOS level was measured through a Seahorse XFe96 cell metabolic analyzer. Flow cytometry was applied to measure mitochondrial status. Real-time qPCR and western blot were used to analyze the expression of mitochondrial or inflammatory factors. MLL-AF9-induced leukemic mice were conducted to measure the anti-leukemia effect of chidamide.

RESULTS

Here, we reported that AML patients with high OXPHOS level were in a poor prognosis, which was associated with high expression of HDAC1/3 (TCGA). Inhibition of HDAC1/3 by chidamide inhibited cell proliferation and induced apoptotic cell death in AML cells. Intriguingly, chidamide could disrupt mitochondrial OXPHOS as assessed by inducing mitochondrial superoxide and reducing oxygen consumption rate, as well as decreasing mitochondrial ATP production. We also observed that chidamide augmented HK1 expression, while glycolysis inhibitor 2-DG could reduce the elevation of HK1 and improve the sensitivity of AML cells exposed to chidamide. Furthermore, HDAC3 was correlated with hyperinflammatory status, while chidamide could downregulate the inflammatory signaling in AML. Notably, chidamide eradicated leukemic cells in vivo and prolonged the survival time of MLL-AF9-induced AML mice.

CONCLUSION

Chidamide disrupted mitochondrial OXPHOS, promoted cell apoptosis and reduced inflammation in AML cells. These findings exhibited a novel mechanism that targeting OXPHOS would be a novel strategy for AML treatment.

DNA methylation landscape reveals LIN7A as a decitabine-responsive marker in patients with t(8;21) acute myeloid leukemia

BACKGROUND

Despite its inconsistent response rate, decitabine, a demethylating agent, is often used as a non-intensive alternative therapeutic agent for acute myeloid leukemia (AML). It has been reported that relapsed/refractory AML patients with t(8;21) translocation achieved better clinical outcomes with a decitabine-based combination regimen than other AML subtypes; however, the mechanisms underlying this phenomenon remain unknown. Herein, the DNA methylation landscape of de novo patients with the t(8;21) translocation was compared with that of patients without the translocation. Moreover, the methylation changes induced by decitabine-based combination regimens in de novo/complete remission paired samples were investigated to elucidate the mechanisms underlying the better responses observed in t(8;21) AML patients treated with decitabine.

METHODS

Thirty-three bone marrow samples from 28 non-M3 AML patients were subjected to DNA methylation sequencing to identify the differentially methylated regions and genes of interest. TCGA-AML Genome Atlas-AML transcriptome dataset was used to identify decitabine-sensitive genes that were downregulated following exposure to a decitabine-based regimen. In addition, the effect of decitabine-sensitive gene on cell apoptosis was examined in vitro using Kasumi-1 and SKNO-1 cells.

RESULTS

A total of 1377 differentially methylated regions that specifically responsive to decitabine in t(8;21) AML were identified, of which 210 showed hypomethylation patterns following decitabine treatment aligned with the promoter regions of 72 genes. And the methylation-silencing genes, LIN7A, CEBPA, BASP1, and EMB were identified as critical decitabine-sensitive genes in t(8;21) AML. Moreover, AML patients with hypermethylated LIN7A and reduced LIN7A expression had poor clinical outcomes. Meanwhile, the downregulation of LIN7A inhibited decitabine/cytarabine combination treatment-induced apoptosis in t(8;21) AML cells in vitro.

CONCLUSION

The findings of this study suggest that LIN7A is a decitabine-sensitive gene in t(8;21) AML patients that may serve as a prognostic biomarker for decitabine-based therapy.

The Implication of Topoisomerase II Inhibitors in Synthetic Lethality for Cancer Therapy

DNA topoisomerase II (Top2) is essential for all eukaryotic cells in the regulation of DNA topology through the generation of temporary double-strand breaks. Cancer cells acquire enhanced Top2 functions to cope with the stress generated by transcription and DNA replication during rapid cell division since cancer driver genes such as Myc and EZH2 hijack Top2 in order to realize their oncogenic transcriptomes for cell growth and tumor progression. Inhibitors of Top2 are therefore designed to target Top2 to trap it on DNA, subsequently causing protein-linked DNA breaks, a halt to the cell cycle, and ultimately cell death. Despite the effectiveness of these inhibitors, cancer cells can develop resistance to them, thereby limiting their therapeutic utility. To maximize the therapeutic potential of Top2 inhibitors, combination therapies to co-target Top2 with DNA damage repair (DDR) machinery and oncogenic pathways have been proposed to induce synthetic lethality for more thorough tumor suppression. In this review, we will discuss the mode of action of Top2 inhibitors and their potential applications in cancer treatments.

Chidamide works synergistically with Dasatinib by inducing cell-cycle arrest and apoptosis in acute myeloid leukemia cells

This research aimed to explore whether Chidamide works synergistically with Dasatinib in the therapy of Acute myeloid leukemia (AML) and the potential molecular mechanism. The inhibition rate of the Dasatinib and Chidamide combination was significantly better than that of the single-drug application for HL-60 cells. The combination of Dasatinib and Chidamide significantly enhanced the Abnormal histone deacetylase (HDAC) inhibitory activity of Chidamide in Kasumi-1 and HL-60 cells. In the combined group, the proportion of S phase was significantly decreased, and the proportions of G2/M phase were significantly increased. The inhibitory rate of CD34+ CD38- HL-60 cells or Kasumi-1 cells was elevated when the cells were disposed with both Chidamide and Dasatinib. Dasatinib and Chidamide had synergistic antitumor effect. The combination with Dasatinib enhanced the HDAC inhibitory activity of Chidamide, promoted cell apoptosis and cell-cycle arrest of AML cells, and enhanced the inhibition of leukemia stem cell proliferation.

Therapeutic potential of tucidinostat, a subtype-selective HDAC inhibitor, in cancer treatment

Histone deacetylase (HDAC) is one of the most characterized epigenetic modifiers, modulating chromatin structure and gene expression, which plays an important role in cell cycle, differentiation and apoptosis. Dysregulation of HDAC promotes cancer progression, thus inhibitors targeting HDACs have evidently shown therapeutic efficacy in multiple cancers. Tucidinostat (formerly known as chidamide), a novel subtype-selective HDAC inhibitor, inhibits Class I HDAC1, HDAC2, HDAC3, as well as Class IIb HDAC10. Tucidinostat is approved in relapsed or refractory (R/R) peripheral T-cell lymphoma (PTCL), advanced breast cancer and R/R adult T-cell leukemia-lymphoma (ATLL). Compared with other HDAC inhibitors, tucidinostat shows notable antitumor activity, remarkable synergistic effect with immunotherapy, and manageable toxicity. Here, we comprehensively summarize recent advances in tucidinostat as both monotherapy and a regimen of combination therapy in both hematological and solid malignancies in clinic. Further studies will endeavor to identify more combination strategies with tucidinostat and to identify specific clinical biomarkers to predict the therapeutic effect.

The dual role of autophagy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a severe hematologic malignancy prevalent in older patients, and the identification of potential therapeutic targets for AML is problematic. Autophagy is a lysosome-dependent catabolic pathway involved in the tumorigenesis and/or treatment of various cancers. Mounting evidence has suggested that autophagy plays a critical role in the initiation and progression of AML and anticancer responses. In this review, we describe recent updates on the multifaceted functions of autophagy linking to genetic alterations of AML. We also summarize the latest evidence for autophagy-related genes as potential prognostic predictors and drivers of AML tumorigenesis. We then discuss the crosstalk between autophagy and tumor cell metabolism into the impact on both AML progression and anti-leukemic treatment. Moreover, a series of autophagy regulators, i.e., the inhibitors and activators, are described as potential therapeutics for AML. Finally, we describe the translation of autophagy-modulating therapeutics into clinical practice. Autophagy in AML is a double-edged sword, necessitating a deeper understanding of how autophagy influences dual functions in AML tumorigenesis and anti-leukemic responses.

RIPK1 inhibition enhances the therapeutic efficacy of chidamide in FLT3-ITD positive AML, both in vitro and in vivo

Acute myeloid leukemia (AML) with FLT3-ITD mutation accounts for a large proportion of relapsed/refractory AML with poor prognosis. RIPK1 is a known key regulator of necroptosis and RIPK1 inhibition shows anti-AML effects in vitro. Chidamide is a histone deacetylase inhibitor (HDACi) with proven ability to induce apoptosis in FLT3-ITD positive AML cells. In the present study, we evaluated the effects of the combination of 22b, a novel RIPK1 inhibitor, and chidamide on proliferation and apoptosis in FLT3-ITD positive AML cell lines and primary cells. The results showed that 22b could significantly enhance the anti-leukemia effect of low-dose chidamide both on cell lines and primary cells. In a subcutaneous xenograft AML model, the combination of 22b and chidamide exhibited obviously elevated anti-tumor activity. In conclusion, our results support that the combination of RIPK1 inhibitor 22b and chidamide may be a novel therapeutic avenue for FLT3-ITD positive AML patients.

Targeting cancer epigenetic pathways with small-molecule compounds: Therapeutic efficacy and combination therapies

Epigenetics mainly refers to covalent modifications to DNA or histones without affecting genomes, which ultimately lead to phenotypic changes in cells or organisms. Given the abundance of regulatory targets in epigenetic pathways and their pivotal roles in tumorigenesis and drug resistance, the development of epigenetic drugs holds a great promise for the current cancer therapy. However, lack of potent, selective, and clinically tractable small-molecule compounds makes the strategy to target cancer epigenetic pathways still challenging. Therefore, this review focuses on epigenetic pathways, small molecule inhibitors targeting DNA methyltransferase (DNMT) and small molecule inhibitors targeting histone modification (the main regulatory targets are histone acetyltransferases (HAT), histone deacetylases (HDACs) and histone methyltransferases (HMTS)), as well as the combination strategies of the existing epigenetic therapeutic drugs and more new therapies to improve the efficacy, which will shed light on a new clue on discovery of more small-molecule drugs targeting cancer epigenetic pathways as promising strategies in the future.