Deubiquitinases at the interplay between hematopoietic stem cell aging and myelodysplastic transformation.

Hematopoietic stem cells (HSC) maintain blood production throughout life. Nevertheless, HSC functionality deteriorates upon physiological aging leading to the increased prevalence of haematological diseases and hematopoietic malignancies in the elderly. Deubiquitinating enzymes (DUBs) by reverting protein ubiquitination ensure proper proteostasis, a key process in HSC maintenance and fitness.

[Epigenetic dysregulation and emerging treatment strategies in myelodysplastic syndromes].

The epigenome regulates transcription of target genes through DNA methylation- or histone methylation/acetylation/phosphorylation/ubiquitination-mediated alteration of genomic function or chromatin conformation. Recent genomic studies have shown that multiple genes encoding epigenetic regulators are frequently and recurrently mutated in MDS, suggesting that epigenetic dysregulation is significantly associated with the molecular pathogenesis and clinical features of MDS. In this review, we will present our recent findings together with others, focusing on physiological molecular functions of epigenetic regulators recurrently mutated in MDS and on functional correlation between dysregulated epigenomic regulators and molecular pathogenesis/clinical features of MDS.

Monitoring molecular changes in the management of myelodysplastic syndromes.

The ongoing or anticipated therapeutic advances as well as previous experience in other malignancies, including acute myeloid leukaemia, have made molecular monitoring a potential interesting tool for predicting outcomes and demonstrating treatment efficacy in patients with myelodysplastic syndromes (MDS). The important genetic heterogeneity in MDS has made challenging the establishment of recommendations. In this context, high-throughput/next-generation sequencing (NGS) has emerged as an attractive tool, especially in patients with high-risk diseases. However, its implementation in clinical practice still suffers from a lack of standardization in terms of sensitivity, bioinformatics and result interpretation. Data from literature, mostly gleaned from retrospective cohorts, show NGS monitoring when used appropriately could help clinicians to guide therapy, detect early relapse and predict disease evolution. Translating these observations into personalized patient management requires a prospective evaluation in clinical research and remains a major challenge for the next years.

Characterization of CD34+ Cells from Patients with Acute Myeloid Leukemia (AML) and Myelodysplastic Syndromes (MDS) Using a t-Distributed Stochastic Neighbor Embedding (t-SNE) Protocol.

Using multi-color flow cytometry analysis, we studied the immunophenotypical differences between leukemic cells from patients with AML/MDS and hematopoietic stem and progenitor cells (HSPCs) from patients in complete remission (CR) following their successful treatment. The panel of markers included CD34, CD38, CD45RA, CD123 as representatives for a hierarchical hematopoietic stem and progenitor cell (HSPC) classification as well as programmed death ligand 1 (PD-L1). Rather than restricting the evaluation on a 2- or 3-dimensional analysis, we applied a t-distributed stochastic neighbor embedding (t-SNE) approach to obtain deeper insight and segregation between leukemic cells and normal HPSCs. For that purpose, we created a t-SNE map, which resulted in the visualization of 27 cell clusters based on their similarity concerning the composition and intensity of antigen expression. Two of these clusters were "leukemia-related" containing a great proportion of CD34+/CD38- hematopoietic stem cells (HSCs) or CD34+ cells with a strong co-expression of CD45RA/CD123, respectively. CD34+ cells within the latter cluster were also highly positive for PD-L1 reflecting their immunosuppressive capacity. Beyond this proof of principle study, the inclusion of additional markers will be helpful to refine the differentiation between normal HSPCs and leukemic cells, particularly in the context of minimal disease detection and antigen-targeted therapeutic interventions. Furthermore, we suggest a protocol for the assignment of new cell ensembles in quantitative terms, via a numerical value, the Pearson coefficient, based on a similarity comparison of the t-SNE pattern with a reference.

Two-Time Multiplexed Targeted Next-Generation Sequencing Might Help the Implementation of Germline Screening Tools for Myelodysplastic Syndromes/Hematologic Neoplasms.

Next-generation sequencing (NGS) tools have importantly helped the classification of myelodysplastic syndromes (MDS), guiding the management of patients. However, new concerns are under debate regarding their implementation in routine clinical practice for the identification of germline predisposition. Cost-effective targeted NGS tools would improve the current standardized studies and genetic counseling. Here, we present our experience in a preliminary study detecting variants using a two-time multiplexed library strategy. Samples from different MDS patients were first mixed before library preparation and later multiplexed for a sequencing run. Two different mixes including a pool of three (3×) and four (4×) samples were evaluated. The filtered variants found in the individually sequenced samples were compared with the variants found in the two-time multiplexed studies to determine the detection efficiency scores. The same candidate variants were found in the two-time multiplexed studies in comparison with the individual tNGS. The variant allele frequency (VAF) values of the candidate variants were also compared. No significant differences were found between the expected and observed VAF percentages in both the 3× (p-value 0.74) and 4× (p-value 0.34) multiplexed studies. Our preliminary results suggest that the two-time multiplexing strategy might have the potential to help reduce the cost of evaluating germline predisposition.

An unusual response to 5-azacitidine by a patient with chronic myelomonocytic leukemia.

Key Clinical Message: Hypomethylating agents may be useful in some but not all cases of myelodysplastic syndromes. In some versions of these conditions, this treatment may yield deleterious results. Abstract: Chronic myelomonocytic leukemia (CMML) is considered to be a heterogeneous group of hematopoietic neoplasms. Usually it shares the features of myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS) and is known as MDS/MPN. It occurs mostly in the elderly and has an inherent tendency to transform to acute myeloid leukemia. FDA has approved hypomethylating agents (HMAs) such as 5-azacitidine (AZA) and decitabine (DEC) for the treatment of this disorder. The extent of response rate to AZA varies considerably among patients. Our report describes a patient with CMML who not only did not respond to a conventional dose of intravenous (IV) therapy with AZA, but showed marked progression of the disease with the leucocyte count rising exponentially while undergoing the aforesaid treatment. We believe this is the first such case reported in the currently extant literature.

Role of innate immunological/inflammatory pathways in myelodysplastic syndromes and AML: a narrative review.

Dysregulation of the innate immune system and inflammatory-related pathways has been implicated in hematopoietic defects in the bone marrow microenvironment and associated with aging, clonal hematopoiesis, myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). As the innate immune system and its pathway regulators have been implicated in the pathogenesis of MDS/AML, novel approaches targeting these pathways have shown promising results. Variability in expression of Toll like receptors (TLRs), abnormal levels of MyD88 and subsequent activation of NF-κß, dysregulated IL1-receptor associated kinases (IRAK), alterations in TGF-ß and SMAD signaling, high levels of S100A8/A9 have all been implicated in pathogenesis of MDS/AML. In this review we not only discuss the interplay of various innate immune pathways in MDS pathogenesis but also focus on potential therapeutic targets from recent clinical trials including the use of monoclonal antibodies and small molecule inhibitors against these pathways.

Liquid biopsies and minimal residual disease in myeloid malignancies.

Minimal residual disease (MRD) assessment through blood component sampling by liquid biopsies (LBs) is increasingly being investigated in myeloid malignancies. Blood components then undergo molecular analysis by flow cytometry or sequencing techniques and can be used as a powerful tool for prognostic and predictive purposes in myeloid malignancies. There is evidence and more is evolving about the quantification and identification of cell-based and gene-based biomarkers in myeloid malignancies to monitor treatment response. MRD based acute myeloid leukemia protocol and clinical trials are currently incorporating LB testing and preliminary results are encouraging for potential widespread use in clinic in the near future. MRD monitoring using LBs are not standard in myelodysplastic syndrome (MDS) but this is an area of active investigation. In the future, LBs can replace more invasive techniques such as bone marrow biopsies. However, the routine clinical application of these markers continues to be an issue due to lack of standardization and limited number of studies investigating their specificities. Integrating artificial intelligence (AI) could help simplify the complex interpretation of molecular testing and reduce errors related to operator dependency. Though the field is rapidly evolving, the applicability of MRD testing using LB is mostly limited to research setting at this time due to the need for validation, regulatory approval, payer coverage, and cost issues. This review focuses on the types of biomarkers, most recent research exploring MRD and LB in myeloid malignancies, ongoing clinical trials, and the future of LB in the setting of AI.

SF3B1 mutations in myelodysplastic syndromes: A potential therapeutic target for modulating the entire disease process.

Myelodysplastic syndromes (MDS) are clonal hematologic malignancies characterized by ineffective hematopoiesis and dysplasia of the myeloid cell lineage and are characterized by peripheral blood cytopenia and an increased risk of transformation to acute myeloid leukemia (AML). Approximately half of the patients with MDS have somatic mutations in the spliceosome gene. Splicing Factor 3B Subunit 1A (SF3B1), the most frequently occurring splicing factor mutation in MDS is significantly associated with the MDS-RS subtype. SF3B1 mutations are intimately involved in the MDS regulation of various pathophysiological processes, including impaired erythropoiesis, dysregulated iron metabolism homeostasis, hyperinflammatory features, and R-loop accumulation. In the fifth edition of the World Health Organization (WHO) classification criteria for MDS, MDS with SF3B1 mutations has been classified as an independent subtype, which plays a crucial role in identifying the disease phenotype, promoting tumor development, determining clinical features, and influencing tumor prognosis. Given that SF3B1 has demonstrated therapeutic vulnerability both in early MDS drivers and downstream events, therapy based on spliceosome-associated mutations is considered a novel strategy worth exploring in the future.

Clinical significance of prognostic nutritional index in myelodysplastic syndrome.

BACKGROUND: Prognostic nutritional index has been found to be related to the clinical outcomes of patients with cancer. However, its role in myelodysplastic syndromes (MDS) patients is unclear. We aimed to assess the value of nutritional status in predicting the prognosis of MDS patients. METHODS: Totally 121 MDS patients were analyzed retrospectively. The prognostic nutritional index (PNI) was used to assess nutritional status of the patients. The bio-informatics tool X-tile was used to define the threshold, and accordingly patients were divided into PNIlow and PNIhigh groups, the characteristics were compared between two groups. RESULTS: The PNIhigh was associated with better OS (Overall Survival) than PNIlow in MDS patients (Median OS, 28.03 months versus 19.63 months, P = 0.0205). But there were no statistical differences in PFS (Progression-Free-Survival) between the two groups (P = 0.9373). The univariable and multivariable COX proportional hazard analysis adjusted for age, gender, platelet count, HB level and IPSS-R scores, and the results showed that PNI is a useful index in the evaluation of the OS of MDS (HR 0.588, 95%CI 0.374-0.926, P = 0.024). CONCLUSION: PNI would be a simple and immediately available tool for predicting the prognosis of MDS.

Over expression of mTOR gene predicts overall survival in myelodysplastic syndromes.

BACKGROUND: Myelodysplastic syndromes (MDS) is defined as heterogenous disease, it contains heterogenous leukemic stem cells with various degree of cell differentiation. The perturbation of genes involved in myeloid progenitor cell growth, differentiation and proliferation lead to morphologic dysplasia, maturation arrest, ineffective hematopoiesis hence the cytopenias and propensity to develop into acute myeloid leukemia (AML). Heterogeneous subsets of MDS patients have been defined by their clinical and biologic abnormalities. These different features lead to the development of different prognostic system; however, these approaches are limited in predicting clinical course, and management of patients remains challenging given the uncertainty of the time course of disease progression. It is of importance to identify transcriptomic marker causing maturational and differentiation arrest which could help in understanding the pathogenesis of disease. METHODS AND RESULTS: We have studied differential gene expression profiles (GEPs) in CD34 + marrow cells from myelodysplastic syndrome (MDS) patients (n = 14) and control CD34 + cells using Affymetrix Human Clariom S microarray with 20,000 well annotated genes. We found 4165 genes significantly (p < 0.05) differentially expressed in MDS. Using stringent bioinformatics analyses, we were able to identify few genes (MAPK8, JUNB, mTOR) which were differentially upregulated i.e. 5.39, 73.61 and 2.7 fold change observed in MDS than control and also validated (n = 60) these genes by RT - qPCR. Kaplan - Meier survival analysis indicated that MAPK8 and JUNB could be poor prognostic marker as patients with increased expression showed poor survival, whereas surprisingly mTOR increased expression proved to be good prognostic marker. The correlation analysis showed that the level of gene (MAPK8, JUNB, mTOR) expression was significantly (p ≤ 0.05) associated with frequency of genetic lesions. Interestingly the increased expression of MAPK8 was significantly accompanied with ASXL1 gene mutation. CONCLUSION: Our study showed an elevation of TNF and AMPK signalling pathways in MDS. TNF signalling might be mediating the proliferative advantage to myeloid clonal cells (mutation carrying cells) over normal cells, whereas, AMPK signalling could be acting as protector against it (favouring normal cells). Hence it would be interesting to explore the functions and pathways associated with mTOR, AMPK, MAPK8 and JUNB in myelopoiesis related diseases like MDS.

Prognostic value of the controlling nutritional status score in patients with myelodysplastic syndromes.

Background: Myelodysplastic syndromes (MDS) are a heterogeneous spectrum of clonal hematopoietic disorders with varying degrees of cytopenia and morphologic dysplasia. The controlling nutritional status (CONUT) score, an easy-to-use tool for assessing the nutritional status, was reported as an independent prognostic factor in cancer patients. However, its role in patients with MDS is unclear. Objective: We aimed to explore the impact of CONUT score on the prognosis of patients with MDS, which is of great significance for clinical treatment. Methods: A total of 121 patients with MDS were analyzed. The CONUT score was calculated prior to therapy. The bio-informatics tool X-tile was used to define the CONUT score and the threshold of 4 points was determined to predict the prognosis. Patients were divided into CONUTlow and CONUThigh groups, and the characteristics were compared between two groups. Results: Results show that CONUTlow was associated with better overall survival (OS) than CONUThigh patients (Median OS, 30.20 vs. 19.63 months, p = 0.0003). However, there were no statistical differences in progression-free survival (PFS) between the two groups (p = 0.2683). Results of univariate and multivariate COX proportional hazard analysis adjusted for bone marrow blasts level, platelet count, International Prognostic Scoring System (IPSS) scores, gender, and hemoglobin (Hb) level showed that the CONUT score was useful in the evaluation standard of OS of MDS (hazard ratio (HR) 2.297, 95% CI 1.441-3.663, p < 0.001). Conclusions: The CONUT, as a novel immuno-nutritional biomarker, may be useful in predicting the OS of MDS.

Dynamics of PD-1 expression are associated with treatment efficacy and prognosis in patients with intermediate/high-risk myelodysplastic syndromes under hypomethylating treatment.

Hypomethylating agents (HMAs) are widely used in patients with higher-risk MDS not eligible for stem cell transplantation. However, the general response rate by HMAs is lesser than 50% in MDS patients, while the relapse rate is high. Emerging evidence indicates that demethylating effects committed by HMAs may facilitate the up-regulation of a range of immune checkpoints or cancer suppressor genes in patients with MDS, among which the programmed death protein 1 (PD-1) and its ligands are demonstrated to be prominent and may contribute to treatment failure and early relapse. Although results from preliminary studies with a limited number of enrolled patients indicate that combined administration of PD-1 inhibitor may yield extra therapeutic benefit in some MDS patients, identifications of this subgroup of patients and optimal timing for the anti-PD-1 intervention remain significant challenges. Dynamics of immune checkpoints and associated predictive values during HMA-treatment cycles remained poorly investigated. In this present study, expression levels of immune checkpoints PD-1 and its ligands PD-L1 and PD-L2 were retrospectively analyzed by quantitative PCR (Q-PCR) in a total of 135 myelodysplastic syndromes (MDS) cohort with higher-risk stratification. The prognostic value of dynamics of these immune checkpoints during HMA cycles was validated in two independent prospective cohorts in our center (NCT01599325 and NCT01751867). Our data revealed that PD-1 expression was significantly higher than that in younger MDS patients (age ≤ 60) and MDS with lower IPSS risk stratification (intermediate risk-1). A significantly up-regulated expression of PD-1 was seen during the first four HMA treatment cycles in MDS patients, while similar observation was not seen concerning the expression of PD-L1 or PD-L2. By utilizing binary logistic regression and receiver operating characteristic (ROC) models, we further identified that higher or equal to 75.9 PD-1 expressions after 2 cycles of HMA treatment is an independent negative prognostic factor in predicting acute myeloid leukemia (AML) transformation and survival. Collectively, our data provide rationales for monitoring the expression of PD-1 during HMA treatment cycles, a higher than 75.9 PD-1 expression may identify patients who will potentially benefit from the combined therapy of HMA and PD-1 inhibitors.

Phase Ib study of eltrombopag and azacitidine in patients with high-risk myelodysplastic syndromes and related disorders (the ELASTIC study).

Treating adverse risk myelodysplastic syndromes with azacitidine exacerbates thrombocytopenia. We report a study of eltrombopag in combination with azacitidine using a 3 + 3 cohort design. Patients with baseline platelets of <150 × 109 /l received eltrombopag ranging from 25 to 300 mg. An 8-day pre-phase of eltrombopag was followed by two cycles of combined therapy. Amongst 31 patients, there were no dose-limiting toxicities. The maximum tolerated dose (MTD) was 300 mg. Transient increases in bone marrow blasts at day 8 were common but no patient had protocol-defined progression following eltrombopag monotherapy. Marrow response rates after three and six treatment cycles were 32% and 29% respectively. In all, 70% of patients treated below and 36% treated at the MTD achieved a modified International Working Group 2006 platelet response at the end of cycle two. Of the platelet transfusion independent patients at baseline, 67% treated at the MTD became transfusion dependent during the first two cycles of treatment. Apart from lack of disease progression, our findings concur with a previously reported Phase III study (A StUdy of eltromboPag in myelodysPlastic SyndrOmes Receiving azaciTidine [SUPPORT]). We conclude that eltrombopag/azacitidine is safe in terms of conventional measures defined by adverse-event reporting. However, in light of SUPPORT and our own descriptive findings regarding efficacy, further combination studies in high-risk disease should be considered with caution.

Myelodysplastic syndromes are multiclonal diseases derived from hematopoietic stem and progenitor cells.

Myelodysplastic syndromes (MDS) are generally considered as a group of clonal diseases derived from hematopoietic stem cells, but a number of studies have suggested that they are derived from myeloid progenitor cells. We aimed to identify the cell of origin in MDS by single-cell analyses. Targeted single-cell RNA sequencing, covering six frequently mutated genes (U2AF1, SF3B1, TET2, ASXL1, TP53, and DNMT3A) in MDS, was developed and performed on individual cells isolated from the CD34+ and six lineage populations in the bone marrow of healthy donors (HDs) and patients with MDS. The detected mutations were used as clonal markers to define clones. By dissecting the distribution of clones in six lineages, the clonal origin was determined. We identified three mutations both in HDs and patients with MDS, termed clonal hematopoiesis (CH) mutations. We also identified fifteen mutations only detected in patients with MDS, termed MDS mutations. Clonal analysis showed that CH clones marked by CH mutations and MDS clones marked by MDS mutations were derived from hematopoietic stem cells as well as various hematopoietic progenitor cells. Most patients with MDS showed the chimeric state with CH clones and MDS clones. Clone size analysis suggested that CH mutations may not contribute to clonal expansion of MDS. In conclusion, MDS comprise multiple clones derived from hematopoietic stem and progenitor cells.

Transfer of IGF2BP3 Through Ara-C-Induced Apoptotic Bodies Promotes Survival of Recipient Cells.

Cytosine arabinoside (Ara-C) has been the standard therapeutic agent for myelodysplastic syndromes (MDS) and adult acute myeloid leukemia (AML) patients for decades. Considerable progress has been made in development of new treatments for MDS/AML patients, but drug resistance remains a major clinical problem. Apoptotic bodies (ABs), produced by late apoptotic cells, can enclose bioactive components that affect cell-cell interactions and disease progression. We isolated and identified drug-induced ABs from Ara-C-tolerance cells. Treatment of sensitive cells with Ara-C-induced ABs resulted in Ara-C-resistant phenotype. We further investigated components and functions of Ara-C-induced ABs. Proteomics analysis in combination with mass spectrometry revealed that Ara-C-induced ABs carried numerous RNA-binding proteins, notably including insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3). Delivery of AB-encapsulated IGF2BP3 promoted survival of recipient cells by activating PI3K-AKT and p42-44 MAPK pathways. High IGF2BP3 level in ABs from MDS/AML patient plasma was correlated with poor overall survival. Our findings demonstrate that AB-derived IGF2BP3 plays an essential role in acquired Ara-C resistance in MDS/AML patients, and is a potential therapeutic target for suppression of Ara-C resistance.

Prognostic Impact of Platelet-Large Cell Ratio In Myelodysplastic Syndromes.

Background: Myelodysplastic syndromes (MDSs) are a very heterogeneous group of myeloid disorders with high prevalence and risk of developing acute myeloid leukemia. The more accurate risk stratification can provide a better guidance of treatment. The platelet-large cell ratio (P-LCR) is a parameter reported in complete blood cell count tests, and was associated with many diseases, but its role in MDS is not clear. Purpose: This study aims to explore the impact of the P-LCR on the prognosis of patients with MDS, which is of great significance for clinical treatment. Methods: In the retrospective study, 122 newly diagnosed MDS patients were enrolled. We used the bioinformatics tool X-tile to define a P-LCR threshold of 36.7% to predict prognosis. Patients were divided into P-LCRlow and P-LCRhigh groups, and their characteristics were compared between the two groups. Results: Results show that the P-LCRlow was associated with worse overall survival (OS) than the P-LCRhigh patients (median OS, 18.53 months versus 25.77 months, p=0.0057), but there were no statistical differences in progression-free survival (PFS) between the two groups (p=0.2001). The results of univariate and multivariate Cox proportional hazard analyses adjusted for gender, bone marrow blast level, platelet count, and International Prognostic Scoring System scores showed that the P-LCR was useful in the evaluation of PFS [hazard ratio (HR) 0.212, 95%CI 0.064-0.702, p=0.011] and OS of MDS (HR 0.464, 95%CI 0.284-0.757, p=0.002). Conclusion: This study is the first report showing that the P-LCR would be a simple and immediately available biomarker for predicting the prognosis of MDS.

The Coming of Age of Preclinical Models of MDS.

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal bone-marrow diseases with ineffective hematopoiesis resulting in cytopenias and morphologic dysplasia of hematopoietic cells. MDS carry a wide spectrum of genetic abnormalities, ranging from chromosomal abnormalities such as deletions/additions, to recurrent mutations affecting the spliceosome, epigenetic modifiers, or transcription factors. As opposed to AML, research in MDS has been hindered by the lack of preclinical models that faithfully replicate the complexity of the disease and capture the heterogeneity. The complex molecular landscape of the disease poses a unique challenge when creating transgenic mouse-models. In addition, primary MDS cells are difficult to manipulate ex vivo limiting in vitro studies and resulting in a paucity of cell lines and patient derived xenograft models. In recent years, progress has been made in the development of both transgenic and xenograft murine models advancing our understanding of individual contributors to MDS pathology as well as the complex primary interplay of genetic and microenvironment aberrations. We here present a comprehensive review of these transgenic and xenograft models for MDS and future directions.

Detection of Red Blood Cell Membrane Proteins in Myelodysplastic Syndromes Using Eosin-5-Maleimide (EMA) Staining by Flow Cytometry.

Background: Eosin-5-Maleimide (EMA)-based flow cytometry binds to red blood cell (RBC) membrane-associated proteins which can be used to detect red blood cell (RBC) membrane disorders. Myelodysplastic syndromes (MDS) are stem cell disorders resulting in ineffective hematopoiesis which is commonly present with anemia and erythroid dysplasia. Objectives: We aimed to study RBC membrane defects in MDS using flow cytometry for EMA staining. Methods: We enrolled anemic patients who were diagnosed with low-risk MDS (R-IPSS score ≤ 3.5), RBC membrane disorders [hereditary spherocytosis (HS) and Southeast Asian ovalocytosis (SAO)], and normal controls. Complete blood count (CBC) and flow cytometry for EMA staining were performed. Results: There were 16 cases of low-risk MDS, 6 cases of RBC membrane disorders, and 15 control cases. Mean fluorescence intensity (MFI) of EMA binding test in the RBC membrane disorders was significantly lower than controls (17.6 vs. 24.3, p < 0.001), but the EMA binding test in the low-risk MDS was not significantly different than the controls (26.5 vs. 24.3, p = 0.08). Conclusion: the RBC membrane defect in low-risk MDS was not demonstrated as having detection ability using EMA binding test with flow cytometry.

Precision medicine in myeloid malignancies.

Myeloid malignancies have always been at the forefront of an improved understanding of the molecular pathogenesis of cancer. In accordance, over the last years, basic research focusing on the aberrations underlying malignant transformation of myeloid cells has provided the basis for precision medicine approaches and subsequently has led to the development of powerful therapeutic strategies. In this review article, we will recapitulate what has happened since in the 1980s the use of all-trans retinoic acid (ATRA), as a first targeted cancer therapy, has changed one of the deadliest leukemia subtypes, acute promyelocytic leukemia (APL), into one that can be cured without classical chemotherapy today. Similarly, imatinib, the first molecularly designed cancer therapy, has revolutionized the management of chronic myeloid leukemia (CML). Thus, targeted treatment approaches have become the paradigm for myeloid malignancy, but many questions still remain unanswered, especially how identical mutations can be associated with different phenotypes. This might be linked to the impact of the cell of origin, gene-gene interactions, or the tumor microenvironment including the immune system. Continuous research in the field of myeloid neoplasia has started to unravel the molecular pathways that are not only crucial for initial treatment response, but also resistance of leukemia cells under therapy. Ongoing studies focusing on leukemia cell vulnerabilities do already point to novel (targetable) "Achilles heels" that can further improve myeloid cancer therapy.