T-cell dysfunctions in myelodysplastic syndromes.

ABSTRACT: Escape from immune surveillance is a hallmark of cancer. Immune deregulation caused by intrinsic and extrinsic cellular factors, such as altered T-cell functions, leads to immune exhaustion, loss of immune surveillance, and clonal proliferation of tumoral cells. The T-cell immune system contributes to the pathogenesis, maintenance, and progression of myelodysplastic syndrome (MDS). Here, we comprehensively reviewed our current biological knowledge of the T-cell compartment in MDS and recent advances in the development of immunotherapeutic strategies, such as immune checkpoint inhibitors and T-cell- and antibody-based adoptive therapies that hold promise to improve the outcome of patients with MDS.

Clonal landscape and clinical outcomes of telomere biology disorders: somatic rescuing and cancer mutations.

Telomere biology disorders (TBD), caused by pathogenic germline variants in telomere-related genes, present with multi-organ disease and a predisposition to cancer. Clonal hematopoiesis (CH) as a marker of cancer development and survival in TBD is poorly understood. Here, we characterized the clonal landscape of a large cohort of 207 TBD patients with a broad range of age and phenotype. CH occurred predominantly in symptomatic patients and in signature genes typically associated with cancers: PPM1D, POT1, TERT promoter (TERTp), U2AF1S34, and/or TP53. Chromosome 1q gain (Chr1q+) was the commonest karyotypic abnormality. Clinically, multiorgan involvement and CH in TERTp, TP53, and splicing factor genes associated with poorer overall survival. Chr1q+, and splicing factor or TP53 mutations significantly increased the risk of hematologic malignancies, regardless of the clonal burden. Chr1q+ and U2AF1S34 mutated clones were pre-malignant events associated with the secondary acquisition of mutations in genes related to hematologic malignancies. Like known effects of Chr1q+ and TP53-CH, functional studies demonstrated that U2AF1S34 mutations primarily compensated for aberrant upregulation of TP53 and interferon pathways in telomere-dysfunctional hematopoietic stem cells, highlighting the TP53 pathway as a canonical route of malignancy in TBD. In contrast, somatic POT1/PPM1D/TERTp-CH had distinct trajectories unrelated to cancer development. With implications beyond TBD, our data show that telomere dysfunction is a strong selective pressure for CH. In TBD, CH is a poor prognostic marker associated with worse overall survival. The identification of key regulatory pathways that drive clonal transformation in TBD allows the identification of patients at a higher risk of cancer development.

NPM1-mutated myeloid neoplasms are a unique entity not defined by bone marrow blast percentage.

INTRODUCTION: NPM1-mutated (NPM1mut) myeloid neoplasms (MNs) with <20% bone marrow (BM) blasts (NPM1mut MNs<20) are uncommon, and their classification remains inconsistent. METHODS: The clinicopathologic features of 54 patients with NPM1mut MNs <20 were evaluated and compared with wild-type NPM1 MNs <20 and NPM1mut MNs≥20, respectively. RESULTS: NPM1mut MNs had similar features regardless of blast percentage, except for higher IDH2 (29% vs 7%, p = .023) and FLT3 (70% vs 11%, p < .001) frequency in patients with ≥20% BM blasts. Thirty-three (61%) patients with NPM1mut MNs <20 received low-intensity chemotherapy (LIC) and 12 (22%) received intensive chemotherapy (IC). Higher complete remission rates (75% vs 27%, p = .006) and median overall survival (mOS) (not reached vs 30.4 months, p = .06) were observed with IC compared to LIC. Young patients (age <60 years) did not reach mOS either when treated with LIC or IC. Stem cell transplant was associated with increased survival only in patients treated with LIC (HR, 0.24; p = .025). No differences in mOS were observed by BM blast strata (32.2 months, not reached and 46.9 months for <10%, 10%-19%, and ≥20% blasts, p = .700) regardless of treatment modality (LIC: p = .900; IC: p = .360). Twenty-three patients (43%) with NPM1mut MNs <20 had marrow blast progression to ≥20%. CONCLUSIONS: Overall, NPM1mut MNs define a unique entity independent of BM blast percentage.

Chronic Thromboembolic Pulmonary Hypertension after Pulmonary Embolism in SARS-CoV-2.

INTRODUCTION: Chronic thromboembolic pulmonary disease (CTEPD) consists of persistent pulmonary vascular obstruction on imaging and involves long-term functional limitations, with or without chronic thromboembolic pulmonary hypertension (CTEPH). The aim of this study was to evaluate the incidence and risk factors of both persistent pulmonary vascular defects and CTEPH after hospitalization in patients with COVID-19 and PE during a 2-year follow-up. METHODS: A prospective observational study was carried out in a tertiary hospital center. Patients were hospitalized between March 2020 and December 2021 with a diagnosis of PE during SARS-CoV-2 infection. Patients received anticoagulant treatment for at least 3 months and were followed up for 2 years. Between the third and fourth months after discharge, all patients were evaluated for the presence of residual thrombotic defects by CTPA and/or perfusion pulmonary scintigraphy. Clinical findings, lung function tests with DLCO, exercise capacity, and echocardiograms were also assessed. RESULTS: Of the 133 patients included, 18% had persistent thrombotic defects on lung imaging at follow-up. The incidence of CTEPD was 0.75% at 2 years of follow-up. Patients with persistent defects were significantly older, had a higher prevalence of systemic arterial hypertension, higher D-dimer and NT-proBNP levels, and more severe PE at diagnosis. Furthermore, there was a higher prevalence of right ventricular dysfunction on echocardiogram at diagnosis of PE (25.0% vs. 2.7%, p = 0.006). This was the only variable independently related to persistent defects in multivariate analyses (OR: 8.13 [95% CI: 1.82-36.32], p = 0.006). CONCLUSION: The persistence of thrombotic defects after PE is a common finding after SARS-CoV-2 infection, affecting 18% of the population. However, the incidence of CTEPH appears to be lower (0.75%) in COVID-19-related PE compared to that previously observed in PE unrelated to COVID-19.

Phenotypic subtypes of leukaemic transformation in chronic myelomonocytic leukaemia.

Chronic myelomonocytic leukaemia (CMML) is a haematological disorder with high risk of transformation to acute myeloid leukaemia (AML). To characterize the phenotypic and genomic patterns of CMML progression, we evaluated a cohort of 189 patients with AML evolving from CMML. We found that transformation occurs through distinct trajectories characterized by genomic profiles and clonal evolution: monocytic (Mo-AML, 53%), immature myeloid (My-AML, 43%) or erythroid (Ery-AML, 2%). Mo-AML, characterized by expansion of monoblasts and promonocytes (low CD34, CD117 expression; high CD14, CD33, CD56 and CD64 expression), were defined by SRSF2, TET2 and RAS pathway mutation co-dominance and were more likely to evolve from SRSF2-TET2 co-mutant CMML through emergence/expansion of RAS pathway mutant clones. Conversely, My-AML, characterized by expansion of immature myeloid blasts (high frequency of CD34, CD38, CD117; low frequency of CD14, CD64 and CD56 expression) were less likely to exhibit SRSF2-TET2 co-mutations or RAS pathway mutations and had higher frequency of CEBPA mutations. Ery-AML was defined by complex karyotypes and TP53 mutations. A trend towards improved OS and EFS with hypomethylating agent-venetoclax combination was observed in My-AML, but not Mo-AML. These findings define distinct progression of CMML and set the basis for future studies evaluating the role of phenotype-specific therapeutics.

Do GWAS-Identified Risk Variants for Chronic Lymphocytic Leukemia Influence Overall Patient Survival and Disease Progression?

Chronic lymphocytic leukemia (CLL) is the most common leukemia among adults worldwide. Although genome-wide association studies (GWAS) have uncovered the germline genetic component underlying CLL susceptibility, the potential use of GWAS-identified risk variants to predict disease progression and patient survival remains unexplored. Here, we evaluated whether 41 GWAS-identified risk variants for CLL could influence overall survival (OS) and disease progression, defined as time to first treatment (TTFT) in a cohort of 1039 CLL cases ascertained through the CRuCIAL consortium. Although this is the largest study assessing the effect of GWAS-identified susceptibility variants for CLL on OS, we only found a weak association of ten single nucleotide polymorphisms (SNPs) with OS (p < 0.05) that did not remain significant after correction for multiple testing. In line with these results, polygenic risk scores (PRSs) built with these SNPs in the CRuCIAL cohort showed a modest association with OS and a low capacity to predict patient survival, with an area under the receiver operating characteristic curve (AUROC) of 0.57. Similarly, seven SNPs were associated with TTFT (p < 0.05); however, these did not reach the multiple testing significance threshold, and the meta-analysis with previous published data did not confirm any of the associations. As expected, PRSs built with these SNPs showed reduced accuracy in prediction of disease progression (AUROC = 0.62). These results suggest that susceptibility variants for CLL do not impact overall survival and disease progression in CLL patients.

Polymorphisms within Autophagy-Related Genes as Susceptibility Biomarkers for Multiple Myeloma: A Meta-Analysis of Three Large Cohorts and Functional Characterization.

Multiple myeloma (MM) arises following malignant proliferation of plasma cells in the bone marrow, that secrete high amounts of specific monoclonal immunoglobulins or light chains, resulting in the massive production of unfolded or misfolded proteins. Autophagy can have a dual role in tumorigenesis, by eliminating these abnormal proteins to avoid cancer development, but also ensuring MM cell survival and promoting resistance to treatments. To date no studies have determined the impact of genetic variation in autophagy-related genes on MM risk. We performed meta-analysis of germline genetic data on 234 autophagy-related genes from three independent study populations including 13,387 subjects of European ancestry (6863 MM patients and 6524 controls) and examined correlations of statistically significant single nucleotide polymorphisms (SNPs; p < 1 × 10-9) with immune responses in whole blood, peripheral blood mononuclear cells (PBMCs), and monocyte-derived macrophages (MDM) from a large population of healthy donors from the Human Functional Genomic Project (HFGP). We identified SNPs in six loci, CD46, IKBKE, PARK2, ULK4, ATG5, and CDKN2A associated with MM risk (p = 4.47 × 10-4-5.79 × 10-14). Mechanistically, we found that the ULK4rs6599175 SNP correlated with circulating concentrations of vitamin D3 (p = 4.0 × 10-4), whereas the IKBKErs17433804 SNP correlated with the number of transitional CD24+CD38+ B cells (p = 4.8 × 10-4) and circulating serum concentrations of Monocyte Chemoattractant Protein (MCP)-2 (p = 3.6 × 10-4). We also found that the CD46rs1142469 SNP correlated with numbers of CD19+ B cells, CD19+CD3- B cells, CD5+IgD- cells, IgM- cells, IgD-IgM- cells, and CD4-CD8- PBMCs (p = 4.9 × 10-4-8.6 × 10-4) and circulating concentrations of interleukin (IL)-20 (p = 0.00082). Finally, we observed that the CDKN2Ars2811710 SNP correlated with levels of CD4+EMCD45RO+CD27- cells (p = 9.3 × 10-4). These results suggest that genetic variants within these six loci influence MM risk through the modulation of specific subsets of immune cells, as well as vitamin D3-, MCP-2-, and IL20-dependent pathways.

Isogenic GAA-KO Murine Muscle Cell Lines Mimicking Severe Pompe Mutations as Preclinical Models for the Screening of Potential Gene Therapy Strategies.

Pompe disease (PD) is a rare disorder caused by mutations in the acid alpha-glucosidase (GAA) gene. Most gene therapies (GT) partially rely on the cross-correction of unmodified cells through the uptake of the GAA enzyme secreted by corrected cells. In the present study, we generated isogenic murine GAA-KO cell lines resembling severe mutations from Pompe patients. All of the generated GAA-KO cells lacked GAA activity and presented an increased autophagy and increased glycogen content by means of myotube differentiation as well as the downregulation of mannose 6-phosphate receptors (CI-MPRs), validating them as models for PD. Additionally, different chimeric murine GAA proteins (IFG, IFLG and 2G) were designed with the aim to improve their therapeutic activity. Phenotypic rescue analyses using lentiviral vectors point to IFG chimera as the best candidate in restoring GAA activity, normalising the autophagic marker p62 and surface levels of CI-MPRs. Interestingly, in vivo administration of liver-directed AAVs expressing the chimeras further confirmed the good behaviour of IFG, achieving cross-correction in heart tissue. In summary, we generated different isogenic murine muscle cell lines mimicking the severe PD phenotype, as well as validating their applicability as preclinical models in order to reduce animal experimentation.

CT imaging of pulmonary embolism in patients with COVID-19 pneumonia: a retrospective analysis.

OBJECTIVES: To describe imaging and laboratory findings of confirmed PE diagnosed in COVID-19 patients and to evaluate the characteristics of COVID-19 patients with clinical PE suspicion. Characteristics of patients with COVID-19 and PE suspicion who required admission to the intensive care unit (ICU) were also analysed. METHODS: A retrospective study from March 18, 2020, until April 11, 2020. Inclusion criteria were patients with suspected PE and positive real-time reverse-transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2. Exclusion criteria were negative or inconclusive RT-PCR and other chest CT indications. CTPA features were evaluated and severity scores, presence, and localisation of PE were reported. D-dimer and IL-6 determinations, ICU admission, and previous antithrombotic treatment were registered. RESULTS: Forty-seven PE suspicions with confirmed COVID-19 underwent CTPA. Sixteen patients were diagnosed with PE with a predominant segmental distribution. Statistically significant differences were found in the highest D-dimer determination in patients with PE and ICU admission regarding elevated IL-6 values. CONCLUSION: PE in COVID-19 patients in our series might predominantly affect segmental arteries and the right lung. Results suggest that the higher the D-dimer concentration, the greater the likelihood of PE. Both assumptions should be assessed in future studies with a larger sample size. KEY POINTS: • On CT pulmonary angiography, pulmonary embolism in COVID-19 patients seems to be predominantly distributed in segmental arteries of the right lung, an assumption that needs to be approached in future research. • Only the highest intraindividual determination of d-dimer from admission to CT scan seems to differentiate patients with pulmonary embolism from patients with a negative CTPA. However, interindividual variability calls for future studies to establish cut-off values in COVID-19 patients. • Further studies with larger sample sizes are needed to determine whether the presence of PE could increase the risk of intensive care unit (ICU) admission in COVID-19 patients.

Inflammation in myelodysplastic syndrome pathogenesis.

Inflammation is a key driver of the progression of preleukemic myeloid conditions, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS), to myelodysplastic syndromes (MDS). Inflammation is a critical mediator in the complex interplay of the genetic, epigenetic, and microenvironmental factors contributing to clonal evolution. Under inflammatory conditions, somatic mutations in TET2, DNMT3A, and ASXL1, the most frequently mutated genes in CHIP and CCUS, induce a competitive advantage to hematopoietic stem and progenitor cells, which leads to their clonal expansion in the bone marrow. Chronic inflammation also drives metabolic reprogramming and immune system deregulation, further promoting the expansion of malignant clones. This review underscores the urgent need to fully elucidate the role of inflammation in MDS initiation and highlights the potential of the therapeutical targeting of inflammatory pathways as an early intervention in MDS.

Advances in the management of higher-risk myelodysplastic syndromes: future prospects.

Higher-risk myelodysplastic syndromes (HR-MDS) are defined using a number of prognostic scoring systems that include the degree of cytopenias, percentage of blasts, cytogenetic alterations, and more recently genomic data. HR-MDS encompasses characteristics such as progressive cytopenias, increased bone marrow blasts, unfavorable cytogenetics, and an adverse mutational profile. Survival is generally poor, and patients require therapy to improve outcomes. Hypomethylating agents (HMAs), such as azacitidine, decitabine, and more recently, oral decitabine/cedazuridine, are the only approved therapies for HR-MDS. These are often continued until loss of response, progression, or unacceptable toxicity. Combinations including an HMA plus other drugs have been investigated but have not demonstrated better outcomes compared to single-agent HMA. Moreover, in a disease of high genomic complexity such as HR-MDS, therapy targeting specific genomic abnormalities is of interest. This review will examine the biological underpinnings of HR-MDS, its therapeutic landscape in the frontline and relapsed settings, as well as the impact of hematopoietic stem cell transplantation, the only known curative intervention for this disease.

Therapy-related chronic myelomonocytic leukemia does not have the high-risk features of a therapy-related neoplasm.

ABSTRACT: Therapy-related myeloid neoplasms (t-MNs) arise after exposure to cytotoxic therapies and are associated with high-risk genetic features and poor outcomes. We analyzed a cohort of patients with therapy-related chronic myelomonocytic leukemia (tCMML; n = 71) and compared its features to that of de novo CMML (dnCMML; n = 461). Median time from cytotoxic therapy to tCMML diagnosis was 6.5 years. Compared with dnCMML, chromosome-7 abnormalities (4% vs 13%; P = .005) but not complex karyotype (3% vs 7%; P = .15), were more frequent in tCMML. tCMML was characterized by higher TP53 mutation frequency (4% vs 12%; P = .04) and lower NRAS (6% vs 22%, P = .007) and CBL (4% vs 12%, P = .04) mutation frequency. Prior therapy with antimetabolites (odd ratio [OR], 1.22; 95% confidence interval [CI], 1.05-1.42; P = .01) and mitotic inhibitors (OR, 1.24; 95% CI, 1.06-1.44; P = .009) was associated with NF1 and SETBP1 mutations whereas prior mitotic inhibitor therapy was associated with lower TET2 mutation frequency (OR, 0.71; 95% CI, 0.55-0.92; P = .01). Although no differences in median overall survival (OS) were observed among tCMML and dnCMML (34.7 months vs 35.9 months, P = .26), multivariate analysis for OS revealed that prior chemotherapy was associated with increased risk of death (hazard ratio, 1.76; 95% CI, 1.07-2.89; P = .026). Compared with a cohort of therapy-related myelodysplastic syndrome, tCMML had lower TP53 mutation frequency (12% vs 44.4%, P < .001) and less unfavorable outcomes. In summary, tCMML does not exhibit the high-risk features and poor outcomes of t-MNs.

Targeting MCL1-driven anti-apoptotic pathways overcomes blast progression after hypomethylating agent failure in chronic myelomonocytic leukemia.

RAS pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Here, using single-cell, multi-omics technologies, we seek to dissect the biological mechanisms underlying the initiation and progression of RAS pathway-mutated CMML. We identify that RAS pathway mutations induce transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs) and downstream monocytic populations in response to cell-intrinsic and -extrinsic inflammatory signaling that also impair the functions of immune cells. HSPCs expand at disease progression after therapy with HMA or the BCL2 inhibitor venetoclax and rely on the NF-κB pathway effector MCL1 to maintain survival. Our study has implications for the development of therapies to improve the survival of patients with RAS pathway-mutated CMML.

Characteristics and outcomes of children, adolescent, and young adult patients with myelodysplastic neoplasms: A single-center retrospective analysis.

Myelodysplastic syndrome, or myelodysplastic neoplasms, are a rare finding in pediatric, adolescent, and young adult (AYA) patients. More literature is needed to highlight trends of survival or treatment resistance in subpopulations to improve treatment. Here we report a single center retrospective analysis of pediatric and AYA patients from 2000 to 2022 including molecular and cytogenetic data. Using the IPSS-R and IPSS-M, which have been reported exclusively in adults, and excluding patients with bone marrow failure syndromes, we analyzed 119 pediatric and AYA patients with myelodysplastic neoplasms. Therapy-related myelodysplastic neoplasms were present in 36 % of patients, and 31 % of patients developed acute myeloid leukemia. The 5-year overall survival (OS) rate for the entire cohort was 45 %. Contrary to young adults and older adults, mutations were not common in pediatrics. Those who underwent stem cell transplant (SCT)(at any time) had significantly longer median OS. Although SCT at any time improved OS in the de novo myelodysplastic neoplasm group, the choice of the initial treatment with intensive chemotherapy, hypomethylating agents, or SCT did not significantly alter OS. Median OS was shorter in the pediatric group (<18 years old) and longer for those with isolated deletion of 5q or TET2 mutation, but these were not significant findings. Median OS was significantly shorter in those with monosomy 7 or 7q deletion and those with therapy-related myelodysplastic neoplasms. These findings build on previously reported findings and encourage the use of SCT along with molecular and cytogenetic analysis.

Hematopoietic stem cells with granulo-monocytic differentiation state overcome venetoclax sensitivity in patients with myelodysplastic syndromes.

The molecular mechanisms of venetoclax-based therapy failure in patients with acute myeloid leukemia were recently clarified, but the mechanisms by which patients with myelodysplastic syndromes (MDS) acquire secondary resistance to venetoclax after an initial response remain to be elucidated. Here, we show an expansion of MDS hematopoietic stem cells (HSCs) with a granulo-monocytic-biased transcriptional differentiation state in MDS patients who initially responded to venetoclax but eventually relapsed. While MDS HSCs in an undifferentiated cellular state are sensitive to venetoclax treatment, differentiation towards a granulo-monocytic-biased transcriptional state, through the acquisition or expansion of clones with STAG2 or RUNX1 mutations, affects HSCs' survival dependence from BCL2-mediated anti-apoptotic pathways to TNFα-induced pro-survival NF-κB signaling and drives resistance to venetoclax-mediated cytotoxicity. Our findings reveal how hematopoietic stem and progenitor cell (HSPC) can eventually overcome therapy-induced depletion and underscore the importance of using close molecular monitoring to prevent HSPC hierarchical change in MDS patients enrolled in clinical trials of venetoclax.

Cytogenetic and Molecular Associations with Outcomes in Higher-Risk Myelodysplastic Syndromes Treated with Hypomethylating Agents plus Venetoclax.

PURPOSE: Hypomethylating agents (HMA) combined with venetoclax are an emerging therapeutic strategy for higher-risk myelodysplastic syndromes (HR-MDS). The cytogenetic and molecular factors associated with outcomes with this combination for HR-MDS are incompletely understood. EXPERIMENTAL DESIGN: We pooled patient data from 3 prospective trials evaluating HMA-venetoclax in HR-MDS to study associations between cytogenetic and molecular factors and overall response rate (ORR), overall survival (OS), and event-free survival (EFS). The Kaplan-Meier method was used to estimate time-to-event endpoints. Univariate and multivariate analyses using logistic regression (for ORR) or the Cox proportional hazards model (for OS and EFS) were used to identify associations between clinical, cytogenetic, and molecular factors and outcomes. RESULTS: A total of 80 patients (52 HMA-naïve, 28 HMA-failure) were included. ORR was 90% in HMA-naïve and 57% in HMA-failure. Median OS was 28.2 and 8.3 months in HMA-naïve and HMA-failure, respectively. Median EFS was 17.9 and 5.5 months in HMA-naïve and HMA-failure, respectively. In addition, 24/52 (46%) of the HMA-naïve and 3/28 (11%) of the HMA-failure patients proceeded to allogeneic stem cell transplantation (SCT). Factors associated with inferior outcomes were prior HMA failure, complex cytogenetics, trisomy 8, TP53 mutations, and RAS pathway mutations. Mutations in RNA splicing, DNA methylation, and ASXL1 appeared favorable. Blast percentage was not predictive of outcomes. CONCLUSIONS: Knowledge of cytogenetic and molecular alterations may help identify which patients with HR-MDS benefit the most from venetoclax.

Targeting DNA2 overcomes metabolic reprogramming in multiple myeloma.

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover mechanisms through which MM cells overcome DNA damage, we investigate how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting Interleukin enhancer binding factor 2 (ILF2), a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo adaptive metabolic rewiring to restore energy balance and promote survival in response to DNA damage activation. Using a CRISPR/Cas9 screening strategy, we identify the mitochondrial DNA repair protein DNA2, whose loss of function suppresses MM cells' ability to overcome ILF2 ASO-induced DNA damage, as being essential to counteracting oxidative DNA damage. Our study reveals a mechanism of vulnerability of MM cells that have an increased demand for mitochondrial metabolism upon DNA damage activation.

BATF is a major driver of NK cell epigenetic reprogramming and dysfunction in AML.

Myelodysplastic syndrome and acute myeloid leukemia (AML) belong to a continuous disease spectrum of myeloid malignancies with poor prognosis in the relapsed/refractory setting necessitating novel therapies. Natural killer (NK) cells from patients with myeloid malignancies display global dysfunction with impaired killing capacity, altered metabolism, and an exhausted phenotype at the single-cell transcriptomic and proteomic levels. In this study, we identified that this dysfunction was mediated through a cross-talk between NK cells and myeloid blasts necessitating cell-cell contact. NK cell dysfunction could be prevented by targeting the αvß-integrin/TGF-ß/SMAD pathway but, once established, was persistent because of profound epigenetic reprogramming. We identified BATF as a core transcription factor and the main mediator of this NK cell dysfunction in AML. Mechanistically, we found that BATF was directly regulated and induced by SMAD2/3 and, in turn, bound to key genes related to NK cell exhaustion, such as HAVCR2, LAG3, TIGIT, and CTLA4. BATF deletion enhanced NK cell function against AML in vitro and in vivo. Collectively, our findings reveal a previously unidentified mechanism of NK immune evasion in AML manifested by epigenetic rewiring and inactivation of NK cells by myeloid blasts. This work highlights the importance of using healthy allogeneic NK cells as an adoptive cell therapy to treat patients with myeloid malignancies combined with strategies aimed at preventing the dysfunction by targeting the TGF-ß pathway or BATF.

Emerging treatments for myelodysplastic syndromes: Biological rationales and clinical translation.

Myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by myeloid dysplasia, peripheral blood cytopenias, and increased risk of progression to acute myeloid leukemia (AML). The standard of care for patients with MDS is hypomethylating agent (HMA)-based therapy; however, nearly 50% of patients have no response to the treatment. Patients with MDS in whom HMA therapy has failed have a dismal prognosis and no approved second-line therapy options, so enrollment in clinical trials of experimental agents represents these patients' only chance for improved outcomes. A better understanding of the molecular and biological mechanisms underpinning MDS pathogenesis has enabled the development of new agents that target molecular alterations, cell death regulators, signaling pathways, and immune regulatory proteins in MDS. Here, we review novel therapies for patients with MDS in whom HMA therapy has failed, with an emphasis on the biological rationale for these therapies' development.