The Genetic Landscape of Myelodysplastic Neoplasm Progression to Acute Myeloid Leukemia

Abnormalities in Chromosomes 5 and 7 in Myelodysplastic Syndrome and Acute Myeloid Leukemia

Chromosomes 5 and 7 are large chromosomes that contain close to 1,000 genes each. Deletions of the long arms or loss of the entire chromosome (monosomy) are common defects in myeloid disorders, particularly MDS and AML. Loss of material from either chromosome 5 or 7 results in haploinsufficiency of multiple genes, with some implicated in leukemogenesis. Abnormalities of one or both occur in up to 15% of MDS and AML cases and co-segregate in half of these. Generally, these chromosomal abnormalities are harbingers of adverse risk in both myeloid disorders. A notable exception is del(5q) in 5q- syndrome, a subtype of MDS. In this review, we describe the pathogenesis and genetic consequences of deletions in chromosomes 5 and 7. Furthermore, we provide an overview of current testing methodologies used in the assessment of these chromosomal defects in hematological malignancies and describe the disease associations and prognostic implications of aberrations in chromosomes 5 and 7 in both MDS and AML.

Increased anti-apoptotic (Bcl-2+) and decreased proliferative (Ki-67+) cell fractions during the different maturation stages of bone marrow cell populations in MDS and AML: The potential diagnostic impact of the Bcl-2:Ki-67 ratio

The relationship between apoptosis inhibition and cell proliferation was studied during the maturation stages of erythropoiesis, granulopoiesis, and monopoiesis in patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The anti-apoptotic and proliferative cell fractions were determined in bone marrow aspirates derived from 25 MDS patients and 25 AML patients and compared to 50 nonmalignant cases, using antibodies to Bcl-2 and Ki-67, respectively. These were applied along with ten-color flow cytometry of maturation markers for the three hematopoietic cell lineages. Next, the Bcl-2:Ki-67 ratio was determined as the ratio between the Bcl-2+ and Ki-67+ cell fractions of the specific hematopoietic cell lineages, both in total and during the different stages of maturation. Bone marrow samples from MDS and AML patients showed a significant increase in the anti-apoptotic cell fraction and a reduced proliferative cell compartment compared to non-malignant cases. Overall, the anti-apoptotic cell fraction was particularly increased in the more mature stages, while the proliferative cell fractions were decreased more frequently in the immature stages. These changes varied among different hematopoietic cell lineages. The erythropoietic maturation process showed the most significant differences in both Ki-67+ and Bcl-2+ cell fractions when comparing MDS and AML to non-malignant cases. This difference was restricted to that of the Bcl-2+ cell fractions in the granulopoiesis and that of the Ki-67+ cell fraction of the monopoiesis. All three hematopoietic cell lineages encompass a small fraction of cells (up to 10%) that concurrently exhibit anti-apoptotic and proliferative marker expression. Although MDS and AML patients displayed considerable variability in their anti-apoptotic and proliferation index, the Bcl-2:Ki-67 ratio resulted in a clear separation between the malignant and non-malignant cases. Incorporating this combination of the Bcl-2 and Ki-67 markers into the study of MDS and AML and in future diagnostic workups may provide important insights into the biological behavior of these blood-borne neoplasms and facilitate personalized therapy decisions for patients.

Myelodysplastic syndromes with del(20q) transformed into B-lineage acute lymphoblastic leukemia remaining with del(20q): a case report with literature review

BACKGROUND

The transformation of myelodysplastic syndromes (MDS) into acute myeloid leukemia (AML) is common, while it is extremely rarely for acute lymphoblastic leukemia (ALL) transformation. Herein, we described the clinical and cytogenetic features of a case of MDS with del(20q) transformed into B-lineage ALL (B-ALL) remaining with del(20q).

CASE PRESENTATION

A 66-year-old Chinese man who presented with pancytopenia, bone marrow hypercellularity and obvious megakaryocytes dysplasia were admitted for treatment. Karyotype analysis of leukemic cells revealed the clonal abnormality of del(20q) and he was diagnosed with MDS carrying del(20q). He was administrated with Danazol, cyclosporin A, and lenalidomide for 3 months, and then discontinued due to poor efficacy, severe swelling and aching of gum. He was subsequently treated with Chinese herbs and uninterrupted platelet infusion. After 41 months, this patient evolved into B-ALL. Cytogenetics demonstrated that in addition to the previous abnormality of del(20q), an emerging clonal abnormality of + 21 was observed. Unfortunately, the patient failed to achieve remission after receiving conventional treatment and other symptomatic supportive treatment.

CONCLUSION

This study reported a rare case of B-ALL with del(20q) following MDS with del(20q), and conducted a literature review to explore the clinical features and potential mechanisms of disease transformation in patients with MDS progression to ALL. Collectively, this study will help enrich the knowledge of MDS progression to ALL.

Unveiling Myelodysplastic Syndromes: Exploring Pathogenic Mechanisms and Therapeutic Advances

Myelodysplastic syndromes (MDSs), either primary or secondary, are a heterogeneous group of clonal hematological neoplasms characterized by bone marrow dyshematopoiesis, peripheral blood cytopenia, and the potential risk of acute myeloid leukemia (AML) transformation. The clinical heterogeneity in MDS is a reflection of the underlying multitude of genetic defects playing a role in the pathogenesis. Recent advances in the clinicopathological, immunophenotypic, and molecular landscape in understanding the pathophysiology of MDS lead to evolving and refined classification systems with newer entities. Evolving MDS therapies will target the disease's core mechanisms, allowing for personalized treatment based on individual patient's genes and leading to better outcomes. This review provides an overview of MDS pathogenesis to enhance comprehension of its various subgroups. Additionally, we examine the updated classification systems of the World Health Organization (WHO) and the International Consensus Classification (ICC) pertaining to MDS, along with relevant therapeutic approaches.

Imetelstat: First Approval

Imetelstat (RYTELO™), an oligonucleotide telomerase inhibitor, is being developed by Geron Corporation for the treatment of myeloid hematologic malignancies. In June 2024, imetelstat was approved in the USA for use in adult patients with low- to intermediate-1 risk myelodysplastic syndromes (MDS) with transfusion-dependent anemia requiring 4 or more red blood cell units over 8 weeks who have not responded to or have lost response to or are ineligible for erythropoiesis-stimulating agents (ESA). This article summarizes the milestones in the development of imetelstat leading to this first approval for the treatment of adult patients with low- to intermediate-1 risk MDS with transfusion-dependent anemia.

Dysregulated innate immune signaling cooperates with RUNX1 mutations to transform an MDS-like disease to AML

Dysregulated innate immune signaling is linked to preleukemic conditions and myeloid malignancies. However, it is unknown whether sustained innate immune signaling contributes to malignant transformation. Here we show that cell-intrinsic innate immune signaling driven by miR-146a deletion (miR-146aKO), a commonly deleted gene in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), cooperates with mutant RUNX1 (RUNX1mut) to initially induce marrow failure and features of MDS. However, miR-146aKO hematopoietic stem and/or progenitor cells (HSPCs) expressing RUNX1mut eventually progress to a fatal AML. miR-146aKO HSPCs exhaust during serial transplantation, while expression of RUNX1mut restored their hematopoietic cell function. Thus, HSPCs exhibiting dysregulated innate immune signaling require a second hit to develop AML. Inhibiting the dysregulated innate immune pathways with a TRAF6-UBE2N inhibitor suppressed leukemic miR-146aKO/RUNX1mut HSPCs, highlighting the necessity of TRAF6-dependent cell-intrinsic innate immune signaling in initiating and maintaining AML. These findings underscore the critical role of dysregulated cell-intrinsic innate immune signaling in driving preleukemic cells toward AML progression.

Treatment of Anemia in Lower-Risk Myelodysplastic Syndrome

OPINION STATEMENT

A majority of patients with lower-risk myelodysplastic syndrome (MDS) will present with or develop anemia. Anemia in MDS is associated with decreased quality of life and may correlate with decreased progression-free survival and overall survival. In this state of the art review we summarize current risk stratification approaches to identify lower-risk MDS (LR-MDS), the natural history of the disease, and meaningful clinical endpoints. The treatment landscape of LR-MDS with anemia is also rapidly evolving; we review the role of supportive care, erythropoietin stimulating agents, lenalidomide, luspatercept, hypomethylating agents (HMAs), and immunosuppressive therapy (IST) in the management of LR-MDS with anemia. In patients with deletion 5q (del5q) syndrome lenalidomide has both efficacy and durability of response. For patients without del5q who need treatment, the management approach is impacted by serum erythropoietin (EPO) level, SF3B1 mutation status, and ring sideroblast status. Given the data from the Phase III COMMANDS trial, we utilize luspatercept in those with SF3B1 mutation or ring sideroblasts that have an EPO level < 500 U/L; in patients without an SF3B1 mutation or ring sideroblasts there is equipoise between luspatercept and use of an erythropoietin stimulating agent (ESA). For patients who have an EPO level ≥ 500 U/L or have been previously treated there is not a clear standard of care. For those without previous luspatercept exposure it can be considered particularly if there is an SF3B1 mutation or the presence of ring sideroblasts. Other options include HMAs or IST; the Phase III IMERGE trial supports the efficacy of the telomerase inhibitor imetelstat in this setting and this may become a standard option in the future as well.

Acute Myeloid Leukemia Post Cytotoxic Therapy in Breast Cancer Survivors-Over 23 Years of Single Center Analysis

Background: Acute myeloid leukemia post cytotoxic therapy (AML-pCT) among breast cancer (BC) survivors represents a life-threatening complication. This study aims to assess the clinical outcomes of AML-pCT post BC. Methods: An analysis of all AML patients treated at a single hematology center (2000-2023) was performed to select patients with AML-pCT post BC. We applied the 2022 ELN criteria to define the genetic risk. Results: Among 847 AML patients, 28 were diagnosed with AML-pCT following BC. Complex karyotype (CK) occurred in 23.8% of patients. The median overall survival (OS) was 40 months. The survival outcomes were better after allogenic hematopoietic stem cell transplantation (alloHCT) treatment compared to chemotherapy alone (median OS: 47 versus 7 months, p = 0.008). Patients demonstrating CK showed lower survival compared to those without CK (2-year OS: 25.0% versus 66.2%, p = 0.0048). The multivariable Cox proportional hazards regression model indicated that treatment with alloHCT emerged as a significant factor associated with improved OS. The treatment was associated with superior OS (HR = 0.07, 95% CI = 0.01-0.86, p = 0.04). Conclusions: Patients with AML-pCT following BC were characterized with the highest frequency of adverse genetic risk profiles and demonstrated worse survival rates. AlloHCT should be performed as early as possible in such patients. The growing need for studies on inherited cancer susceptibility underscores the importance of close AML-pCT development monitoring in BC survivors.

Biomarkers of Response to Venetoclax Therapy in Acute Myeloid Leukemia

Recent progress in the use of massive sequencing technologies has greatly enhanced our understanding of acute myeloid leukemia (AML) pathology. This knowledge has in turn driven the development of targeted therapies, such as venetoclax, a BCL-2 inhibitor approved for use in combination with azacitidine, decitabine, or low-dose cytarabine for the treatment of newly diagnosed adult patients with AML who are not eligible for intensive chemotherapy. However, a significant number of AML patients still face the challenge of disease relapse. In this review, we will explore biomarkers that may predict disease progression in patients receiving venetoclax-based therapy, considering both clinical factors and genetic changes. Despite the many advances, we conclude that the identification of molecular profiles for AML patients who will respond optimally to venetoclax therapy remains an unmet clinical need.

Subclones with variants of uncertain clinical significance might contribute to ineffective hemopoiesis and leukemia predisposition

BACKGROUND

Splicing modifications, genomic instability, and hypomethylation are central mechanisms promoting myelodysplasia and acute myeloid leukemia (AML). In this real-life retrospective study, to elucidate pathophysiology of clonal hemopoiesis in hematological malignancies, we investigated clinical significance of mutations in leukemia-related genes of known pathogenetic significance and of variants of uncertain clinical significance (VUS) in a cohort of patients with MDS and AML.

METHODS

A total of 59 consecutive subjects diagnosed with MDS, 48 with AML, and 17 with clonal cytopenia with unknown significance were screened for somatic mutations in AML-related genes by next-generation sequencing.

RESULTS

We showed that TET2, SETBP1, ASXL1, EZH2, RUNX1, SRSF2, DNMT3A, and IDH1/2 were commonly mutated. MDS patients also showed a high genetic complexity, especially for SETBP1. Moreover, the presence of SETBP1 wild-type or two or more simultaneous VUS variants identified a subgroup of AML and MDS patients with better outcome, while the presence of single SETBP1 VUS variant was related to a worse prognosis, regardless TET2 mutational status.

CONCLUSIONS

In conclusions, we linked both pathogenic and VUS variants in AML-related genes to clonal hematopoiesis; therefore, we proposed to consider those variants as prognostic markers in leukemia and myelodysplasia. However, further studies in larger prospective cohorts are required to validate our results.

DNMT3A mutation promotes leukemia development through NAM-NAD metabolic reprogramming

BACKGROUND

DNA methyltransferase 3A (DNMT3A) is frequently mutated in acute myeloid leukemia (AML) with Arg882His (R882H) as the hotspot mutation. It has been reported that DNMT3A mutation plays a key role in leukemogenesis through hypomethylation of some target genes associated with cell growth and differentiation. In this study, we investigated the function of DNMT3A R882H in the malignant progression of AML by regulating metabolic reprogramming.

METHODS

Ultra-High Performance Liquid Chromatography-High Resolution Tandem Mass Spectrometry (UHPLC-HRMS/MS) was used to detect metabolites in the serum of mice harboring Dnmt3a R878H mutation and the wild-type Dnmt3a. Methylated DNA Immunoprecipitation Sequencing (MeDIP-seq) and RNA sequencing (RNA-seq) were used to analyze the levels of DNA methylation and mRNA expression of genes in mouse Gr1⁺ bone marrow cells respectively. The TCGA and GO databases were used to analyze the differential genes between human samples carrying the DNMT3A R882 mutation and the wild-type DNMT3A. Co-immunoprecipitation and immunoblotting were used to illustrate the binding levels of Cyclins-CDKs and CDK inhibitors including CDKN1A and CDKN1B. Flow cytometry was used to analyze the cell differentiation, division, apoptosis and cell cycle. The effect of NAMPT inhibition on leukemia was evaluated by using in vivo fluorescence imaging in NOG mouse model bearing OCI-AML3 cells.

RESULTS

DNMT3A mutation caused high expression of nicotinamide phosphoribosyltransferase (NAMPT), a key enzyme in the nicotinamide adenine dinucleotide (NAD) salvage synthetic pathway, through DNA hypomethylation, and finally led to abnormal nicotinamide (NAM) metabolism and NAD synthesis. The NAM-NAD metabolic abnormalities caused accelerated cell cycle progression. Inhibition of NAMPT can reduce the binding degree between Cyclins-CDKs, and increase the binding interaction of the CDK inhibitors with Cyclins-CDKs complexes. Moreover, cells with high expression of NAMPT were more sensitive to the NAMPT inhibitor FK866 with a lower IC50. The inhibition of NAMPT can remarkably extend the survival time of tumor-bearing mice and reduce the infiltration of tumor cells.

CONCLUSIONS

Taken together, our data showed that DNMT3A mutation caused NAMPT overexpression to induce the reprogramming of NAM-NAD metabolism and contribute to abnormal proliferation, which provided a potential direction for targeted therapy at the metabolic level in AML with DNMT3A mutation.