Hypomethylating agents for the treatment of myelodysplastic syndromes and acute myeloid leukemia: Past discoveries and future directions

Concerted SUMO-targeted ubiquitin ligase activities of TOPORS and RNF4 are essential for stress management and cell proliferation

Protein SUMOylation provides a principal driving force for cellular stress responses, including DNA-protein crosslink (DPC) repair and arsenic-induced PML body degradation. In this study, using genome-scale screens, we identified the human E3 ligase TOPORS as a key effector of SUMO-dependent DPC resolution. We demonstrate that TOPORS promotes DPC repair by functioning as a SUMO-targeted ubiquitin ligase (STUbL), combining ubiquitin ligase activity through its RING domain with poly-SUMO binding via SUMO-interacting motifs, analogous to the STUbL RNF4. Mechanistically, TOPORS is a SUMO1-selective STUbL that complements RNF4 in generating complex ubiquitin landscapes on SUMOylated targets, including DPCs and PML, stimulating efficient p97/VCP unfoldase recruitment and proteasomal degradation. Combined loss of TOPORS and RNF4 is synthetic lethal even in unstressed cells, involving defective clearance of SUMOylated proteins from chromatin accompanied by cell cycle arrest and apoptosis. Our findings establish TOPORS as a STUbL whose parallel action with RNF4 defines a general mechanistic principle in crucial cellular processes governed by direct SUMO-ubiquitin crosstalk.

Pharmacokinetic assessment of low dose decitabine in combination therapies: Development and validation of a sensitive UHPLC-MS/MS method for murine plasma analysis

Decitabine is a DNA methyltransferase inhibitor used in the treatment of acute myeloid leukemia and myelodysplastic syndrome. The notion that ongoing trials are presently exploring the combined use of decitabine, with or without the cytidine deaminase inhibitor cedazuridine, and other antileukemic drugs necessitates a comprehensive understanding of pharmacokinetic properties and an evaluation of drug-drug interaction liabilities. We report here the development and validation of a sensitive UHPLC-MS/MS method for quantifying decitabine in mouse plasma, which should be useful for such studies. The method involved a one-step protein precipitation extraction, and chromatographic separation on an XBridge HILIC column using gradient elution. The method was found to be robust, accurate, precise, and sufficiently sensitive (lower limit of quantitation, 0.4 ng/mL) to determine decitabine concentrations in microvolumes of plasma from mice receiving the agent orally or intravenously in the presence or absence of cedazuridine.

Hypermethylation leads to the loss of HOXA5, resulting in JAG1 expression and NOTCH signaling contributing to kidney fibrosis

Epigenetic regulations, including DNA methylation, are critical to the development and progression of kidney fibrosis, but the underlying mechanisms remain elusive. Here, we show that fibrosis of the mouse kidney was associated with the induction of DNA methyltransferases and increases in global DNA methylation and was alleviated by the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza). Genome-wide analysis demonstrated the hypermethylation of 94 genes in mouse unilateral ureteral obstruction kidneys, which was markedly reduced by 5-Aza. Among these genes, Hoxa5 was hypermethylated at its gene promoter, and this hypermethylation was associated with reduced HOXA5 expression in fibrotic mouse kidneys after ureteral obstruction or unilateral ischemia-reperfusion injury. 5-Aza prevented Hoxa5 hypermethylation, restored HOXA5 expression, and suppressed kidney fibrosis. Downregulation of HOXA5 was verified in human kidney biopsies from patients with chronic kidney disease and correlated with the increased kidney fibrosis and DNA methylation. Kidney fibrosis was aggravated by conditional knockout of Hoxa5 and alleviated by conditional knockin of Hoxa5 in kidney proximal tubules of mice. Mechanistically, we found that HOXA5 repressed Jag1 transcription by directly binding to its gene promoter, resulting in the suppression of JAG1-NOTCH signaling during kidney fibrosis. Thus, our results indicate that loss of HOXA5 via DNA methylation contributes to fibrogenesis in kidney diseases by inducing JAG1 and consequent activation of the NOTCH signaling pathway.

Clinical activity, pharmacokinetics, and pharmacodynamics of oral hypomethylating agents for myelodysplastic syndromes/neoplasms and acute myeloid leukemia: A multidisciplinary review

OBJECTIVE

To review the pharmacokinetic (PK)-pharmacodynamic (PD) profiles, disease setting, dosing, and safety of oral and parenteral hypomethylating agents (HMAs) for the treatment of myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML), and to provide a multidisciplinary perspective on treatment selection and educational needs relating to HMA use.

DATA SOURCES

Clinical and real-world data for parenteral decitabine and azacitidine and two oral HMAs: decitabine-cedazuridine (DEC-C) for MDS and azacitidine (CC-486) for AML maintenance therapy.

DATA SUMMARY

Differences in the PK-PD profiles of oral and parenteral HMA formulations have implications for their potential toxicities and planned use. Oral DEC-C (decitabine 35 mg and cedazuridine 100 mg) has demonstrated equivalent systemic area under the concentration-time curve (AUC) exposure to a 5-day regimen of intravenous (IV) decitabine 20 mg/m2 and showed no significant difference in PD. The AUC equivalence of oral DEC-C and IV decitabine means that these regimens can be treated interchangeably (but must not be substituted within a cycle). Oral azacitidine has a distinct PK-PD profile versus IV or subcutaneous azacitidine, and the formulations are not bioequivalent or interchangeable owing to differences in plasma time-course kinetics and exposures. Clinical trials are ongoing to evaluate oral HMA combinations and novel oral HMAs, such as NTX-301 and ASTX030.

CONCLUSIONS

Treatment with oral HMAs has the potential to improve quality of life, treatment adherence, and disease outcomes versus parenteral HMAs. Better education of multidisciplinary teams on the factors affecting HMA treatment selection may help to improve treatment outcomes in patients with MDS or AML.

MiR-136-5p in cancer: Roles, mechanisms, and chemotherapy resistance

MicroRNAs (miRNAs) have emerged as important regulators of gene expression, and the deregulation of their activity has been linked to the onset and progression of a variety of human malignancies. Among these miRNAs, miR-136-5p has attracted significant attention due to its diverse roles in cancer biology. Mostly, miR-136-5p is downregulated in malignancies. It could inhibit viability, proliferation, migration, invasion and promote apoptosis of tumor cells. This review article provides a comprehensive overview of the current understanding of miR-136-5p in different sorts of human cancers: genital tumors, head and neck tumors, tumors from the digestive and urinary systems, skin cancers, neurologic tumors, pulmonary neoplasms and other cancers by discussing its molecular mechanisms, functional roles, and impact in chemotherapies. In conclusion, miR-136-5p could be a promising new biomarker and potential clinical therapeutic target.

Role of reactive oxygen species in myelodysplastic syndromes

Reactive oxygen species (ROS) serve as typical metabolic byproducts of aerobic life and play a pivotal role in redox reactions and signal transduction pathways. Contingent upon their concentration, ROS production not only initiates or stimulates tumorigenesis but also causes oxidative stress (OS) and triggers cellular apoptosis. Mounting literature supports the view that ROS are closely interwoven with the pathogenesis of a cluster of diseases, particularly those involving cell proliferation and differentiation, such as myelodysplastic syndromes (MDS) and chronic/acute myeloid leukemia (CML/AML). OS caused by excessive ROS at physiological levels is likely to affect the functions of hematopoietic stem cells, such as cell growth and self-renewal, which may contribute to defective hematopoiesis. We review herein the eminent role of ROS in the hematological niche and their profound influence on the progress of MDS. We also highlight that targeting ROS is a practical and reliable tactic for MDS therapy.

Temporal trend in survival for chronic myelomonocytic leukemia in the US: a population-based study

Outcomes for chronic myelomonocytic leukemia (CMML) are insufficiently characterized at the population level. We analyzed epidemiological trends for patients between 2001 and 2017, focusing on age, sex, race, and long-term survivors. Using the Surveillance, Epidemiology, and End Results Program, we studied 3929 patients, in four time-period (tp) cohorts, based on year of diagnosis [2001-2004 (tp1); 2005-2009 (tp2); 2010-2013 (tp3); 2014-2017 (tp4)]. Stable incidence overall, male predominance, and higher incidence for White versus Black and 'Other' races were noted. Three-year relative survival (RS) increased from 27.9% to 36.9% between tp1 and tp4. The most pronounced increase occurred between tp1 and tp2. All subgroups generally experienced RS improvements over time, except notably Black patients. Improvements for patients aged 85+ (3-year RS 8.4-23.6% between tp1 and tp4) and increases in long-term survivors (5-year OS from 13.2-22.3%) were observed. Additional study is warranted to explore these associations, particularly for Black patients.

Pulmonary infections in patients with acute myeloid leukemia receiving frontline treatment with hypomethylating agents

Pulmonary infections (PIs) are a major complication of Acute Myeloid Leukemia (AML) treated with hypomethylating agents (HMA). We retrospectively evaluated 147 AML patients treated frontline with HMA in 2 Centers. Total number of HMA cycles was 1397. There were 88 episodes of PI in 64 patients (43.5%). Thirty-five/147 patients at risk (23.8%) developed at least 1 episode of early PI (during cycles 1-2). Median OS in patients who developed early PI was 3.3 months (95% CI 0.8 - 5.8) versus 10.5 months (95% CI 8.4 - 12.7) in patients without PI or with PI beyond the 2nd cycle (p < .001). Early PIs were an independent factor predicting lower survival (OR 1.94, 95% CI 1.28 - 2.93; p = .002). In conclusion, early PIs are common in AML patients receiving HMA and are associated with an unfavorable outcome. The results of our study raise the issue of a tailored infection prevention strategy.

Phase I Results of Bromodomain and Extra-Terminal Inhibitor PLX51107 in Combination with Azacitidine in Patients with Relapsed/Refractory Myeloid Malignancies

PURPOSE

Treatment outcomes in patients with relapsed/refractory (R/R) myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) remains dismal. On the basis of both extensive preclinical data and emerging clinical data, treatment with bromodomain and extra-terminal domain inhibitors (BETi) is a potential approach for patients with high-risk myeloid malignancies.

PATIENTS AND METHODS

We conducted a phase I trial to study the safety and efficacy of PLX51107 (BETi) and azacitidine combination therapy in patients with R/R AML and high-risk (HR) MDS and studied mechanisms of resistance to the combination therapy.

RESULTS

Thirty-seven patients with HR R/R MDS (n = 4) and R/R AML (n = 33) were treated. Sixteen patients (43%) had MECOM gene rearrangement and 7 other patients had TP53 mutation. Median prior number of therapies was three (range 1-9); 97% had received prior hypomethylating agent and 84% prior venetoclax. Overall response rate was 8/37 (22%): complete remission with incomplete platelet recovery (n = 1); morphologic leukemia-free state (n = 2); hematologic improvement (n = 5). The most common nonhematologic toxicities were febrile neutropenia and pneumonia in 12 (32%) patients each; 6 patients (17%) had severe hyperbilirubinemia. RNA-sequencing analysis of mononuclear cells harvested on treatment (day 3) versus pretreatment showed significant changes in mRNA expressions in responders: downregulation of MYC, BCL2, IL7R, and CDK6 and upregulation of HEXIM1, CD93, DCXR, and CDKN1A. Immunoblot analyses confirmed reduction in protein levels of c-Myc, CDK6, BCL2, and BCL-xL, and induction of BRD4 and HEXIM1 protein levels in responders.

CONCLUSIONS

In a heavily pretreated patient cohort with R/R MDS and AML, PLX51107+ azacitidine was well-tolerated and resulted in modest clinical benefit.

YY1 Knockdown Relieves the Differentiation Block and Restores Apoptosis in AML Cells

In this study we analyzed the expression of Yin and Yang 1 protein (YY1), a member of the noncanonical PcG complexes, in AML patient samples and AML cell lines and the effect of YY1 downregulation on the AML differentiation block. Our results show that YY1 is significantly overexpressed in AML patient samples and AML cell lines and that YY1 knockdown relieves the differentiation block. YY1 downregulation in two AML cell lines (HL-60 and OCI-AML3) and one AML patient sample restored the expression of members of the CEBP protein family, increased the expression of extrinsic growth factors/receptors and surface antigenic markers, induced morphological cell characteristics typical of myeloid differentiation, and sensitized cells to retinoic acid treatment and to apoptosis. Overall, our data show that YY1 is not a secondary regulator of myeloid differentiation but that, if overexpressed, it can play a predominant role in myeloid differentiation block.

Targeting tumor endothelial cells with methyltransferase inhibitors: Mechanisms of action and the potential of combination therapy

Tumor endothelial cells (TECs) reside in the inner lining of blood vessels and represent a promising target for targeted cancer therapy. DNA methylation is a chemical process that involves the transfer of a methyl group to a specific base in the DNA strand, catalyzed by DNA methyltransferase (DNMT). DNMT inhibitors (DNMTis) can inhibit the activity of DNMTs, thereby preventing the transfer of methyl groups from s-adenosyl methionine (SAM) to cytosine. Currently, the most viable therapy for TECs is the development of DNMTis to release cancer suppressor genes from their repressed state. In this review, we first outline the characteristics of TECs and describe the development of tumor blood vessels and TECs. Abnormal DNA methylation is closely linked to tumor initiation, progression, and cell carcinogenesis, as evidenced by numerous studies. Therefore, we summarize the role of DNA methylation and DNA methyltransferase and the therapeutic potential of four types of DNMTi in targeting TECs. Finally, we discuss the accomplishments, challenges, and opportunities associated with combination therapy with DNMTis for TECs.

What's Next after Hypomethylating Agents Failure in Myeloid Neoplasms? A Rational Approach

Hypomethylating agents (HMA) such as azacitidine and decitabine are a mainstay in the current management of patients with myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML) as either single agents or in multidrug combinations. Resistance to HMA is not uncommon, and it can result due to several tumor cellular adaptations. Several clinical and genomic factors have been identified as predictors of HMA resistance. However, the management of MDS/AML patients after the failure of HMA remains challenging in the absence of standardized guidelines. Indeed, this is an area of active research with several potential therapeutic agents currently under development, some of which have demonstrated therapeutic potential in early clinical trials, especially in cases with particular mutational characteristics. Here, we review the latest findings and give a rational approach for such a challenging scenario.

Prediction of survival with lower intensity therapy among older patients with acute myeloid leukemia

BACKGROUND

The aim of this study was to develop a prognostic model for survival in older/unfit patients with newly diagnosed acute myeloid leukemia (AML) who were treated with lower-intensity chemotherapy regimens.

METHODS

The authors reviewed all older/unfit patients with newly diagnosed AML who received lower-intensity chemotherapy from 2000 until 2020 at their institution. A total of 1462 patients were included. They were divided (3:1 basis) into a training (n = 1088) and a validation group (n = 374).

RESULTS

In the training cohort of 1088 patients (median age, 72 years), the multivariate analysis identified 11 consistent independent adverse factors associated with survival: older age, therapy-related myeloid neoplasm, existence of previous myelodysplastic syndrome or myeloproliferative neoplasms, poor performance status, pulmonary comorbidity, anemia, thrombocytopenia, elevated lactate dehydrogenase, cytogenetic abnormalities, and the presence of infection at diagnosis, and therapy not containing venetoclax. The 3-year survival rates were 52%, 24%, 10%, and 1% in favorable, intermediate, poor, and very poor risk, respectively. This survival model was validated in an independent cohort. In a subset of patients in whom molecular mutation profiles were performed in more recent times, adding the mutation profiles after accounting for the effects of previous factors identified IDH2 (favorable), NPM1 (favorable), and TP53 (unfavorable) mutations as molecular prognostic factors.

CONCLUSION

The proposed survival model with lower-intensity chemotherapy in older/unfit patients with newly diagnosed AML may help to advise patients on their expected outcome, to propose different strategies in first complete remission, and to compare the results of different existing or future investigational therapies.

PLAIN LANGUAGE SUMMARY

Lower intensity therapy can be considered for older patients to avoid severe toxicities and adverse events. However, survival prediction in AML was commonly developed in patients who received intensive chemotherapy. In this study, we have proposed a survival model to guide therapeutic approach in older patients who received lower-intensity therapy.

The mesenchymal compartment in myelodysplastic syndrome: Its role in the pathogenesis of the disorder and its therapeutic targeting

Myelodysplastic syndromes include a broad spectrum of malignant myeloid disorders that are characterized by dysplastic ineffective hematopoiesis, reduced peripheral blood cells counts and a high risk of progression to acute myeloid leukemia. The disease arises primarily because of accumulating chromosomal, genetic and epigenetic changes as well as immune-mediated alterations of the hematopoietic stem cells (HSCs). However, mounting evidence suggests that aberrations within the bone marrow microenvironment critically contribute to myelodysplastic syndrome (MDS) initiation and evolution by providing permissive cues that enable the abnormal HSCs to grow and eventually establish and propagate the disease. Mesenchymal stromal cells (MSCs) are crucial elements of the bone marrow microenvironment that play a key role in the regulation of HSCs by providing appropriate signals via soluble factors and cell contact interactions. Given their hematopoiesis supporting capacity, it has been reasonable to investigate MSCs' potential involvement in MDS. This review discusses this issue by summarizing existing findings obtained by in vitro studies and murine disease models of MDS. Furthermore, the theoretical background of targeting the BM-MSCs in MDS is outlined and available therapeutic modalities are described.