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

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell disorders with maturation and differentiation defects exhibiting morphological dysplasia in one or more hematopoietic cell lineages. They are associated with peripheral blood cytopenias and by increased risk for progression into acute myelogenous leukemia. Among their multifactorial pathogenesis, age-related epigenetic instability and the error-rate DNA methylation maintenance have been recognized as critical factors for both the initial steps of their pathogenesis and for disease progression. Although lower-risk MDS is associated with an inflammatory bone marrow microenvironment, higher-risk disease is delineated by immunosuppression and clonal expansion. “Epigenetics” is a multidimensional level of gene regulation that determines the specific gene networks expressed in tissues under physiological conditions and guides appropriate chromatin rearrangements upon influence of environmental stimulation. Regulation of this level consists of biochemical modifications in amino acid residues of the histone proteins’ N-terminal tails and their concomitant effects on chromatin structure, DNA methylation patterns in CpG dinucleotides and the tissue-specific non-coding RNAs repertoire, which are directed against various gene targets. The role of epigenetic modifications is widely recognized as pivotal both in gene expression control and differential molecular response to drug therapies in humans. Insights to the potential of synergistic cooperations of epigenetic mechanisms provide new avenues for treatment development to comfort human diseases with a known epigenetic shift, such as MDS. Hypomethylating agents (HMAs), such as epigenetic modulating drugs, have been widely used in the past years as first line treatment for elderly higher-risk MDS patients; however, just half of them respond to therapy and are benefited. Rational outcome predictors following epigenetic therapy in MDS and biomarkers associated with disease relapse are of high importance to improve our efforts in developing patient-tailored clinical approaches.

Background: The landscape of first-line treatment for acute myeloid leukemia (AML) patients ineligible for intensive chemotherapy has changed remarkably after venetoclax approval. Accumulating real-world data further apprises us with more knowledgeable use. To assess the efficacy and safety challenges in the real-life setting of the combination of hypomethylated agent (HMA) and venetoclax, we conducted a multi-center retrospective study. Methods: Forty adult AML patients treated with the combination of HMA and venetoclax as a first-line treatment after full approval (2020) were included. To confirm VIALE-A results, this group was compared to a historical cohort of 17 chemotherapy-ineligible AML patients treated with HMA monotherapy before 2020. Results: The combination of HMA-venetoclax achieved a composite complete response rate of 86.8% (p < 0.001), median overall survival, and event-free survival of 33.8 and 19.7 months, respectively, in a median follow-up of 17.8 months (p_os < 0.001, HR = 0.276, CI: 0.132–0.575, p_EFS = 0.004, HR = 0.367, CI: 0.174–0.773). High rates of neutropenia (90%) and consequent infection rates (57.5%) were noted. Only 55% of our patients received antifungal prophylaxis, as its use remains controversial, and invasive fungal infections were presented in 7.5%. Conclusions: Evidently, venetoclax-HMA yields high response rates and profound survival benefits in real life and has changed our approach to alternative chemotherapy options.

Aims: Treatment of higher-risk myelodysplastic syndromes (HR-MDS) with azacytidine (AZA) exerts significant effects on the epigenome, primarily through DNA demethylation and reactivation of epigenetically silenced genes. Beyond this established mechanism, molecular AZA-linked effects are increasingly being recognized. Materials and methods: Liquid chromatography combined with mass spectrometry (LC-MS/MS) was employed for the accurate assessment of various RNA and DNA modifications pre- and post-AZA treatment of an HR-MDS cohort (N = 8). Mapping of the AZA treatment-responsive regulatory pathways was performed by miRNA-next generation sequencing (NGS), followed by a multi-layered bioinformatic pipeline, integrating miRNA differential expression, gene set enrichment, and network analyses. The precise number of mitochondrial (mt)DNA copies pre- and post-AZA was evaluated by a digital PCR assay. Results: Cell pathways affected by miRNA differential expression patterns pre- and post-AZA treatment discriminated the clinical phenotypes of Responders against Non-Responders to therapy. Intracellular RNA modifications: N6-methyladenosine (m6A), 5-methylcytidine (m5C), N1-methyladenosine (m1A), 2′-O-methylguanosine (Gm) and adenosine-to-inosine (A → I) editing were evaluated for their potential impact in treatment response. Nuclear DNA/mtDNA methylation profiles and mtDNA copy number reduction manifested the mitochondrial features affected by AZA. Our results suggest that neoplastic HSPCs in HR-MDS Responders to AZA adapt by normalizing glycolytic metabolism and enhancing ribosomal activity. The observed reduction of mtDNA content can be associated with improved survival and suppression of malignant progression. Non-Responders, despite experiencing mtDNA depletion, seem unable to coordinate such metabolic reprogramming and remain disadvantaged to AZA therapy.