Prognostic Mutations in Myelodysplastic Syndrome after Stem-Cell Transplantation

Convergent somatic evolution commences in utero in a germline ribosomopathy

Clonal tracking of cells using somatic mutations permits exploration of clonal dynamics in human disease. Here, we perform whole genome sequencing of 323 haematopoietic colonies from 10 individuals with the inherited ribosomopathy Shwachman-Diamond syndrome to reconstruct haematopoietic phylogenies. In ~30% of colonies, we identify mutually exclusive mutations in TP53, EIF6, RPL5, RPL22, PRPF8, plus chromosome 7 and 15 aberrations that increase SBDS and EFL1 gene dosage, respectively. Target gene mutations commence in utero, resulting in a profusion of clonal expansions, with only a few haematopoietic stem cell lineages (mean 8, range 1-24) contributing ~50% of haematopoietic colonies across 8 individuals (range 4-100% clonality) by young adulthood. Rapid clonal expansion during disease transformation is associated with biallelic TP53 mutations and increased mutation burden. Our study highlights how convergent somatic mutation of the p53-dependent nucleolar surveillance pathway offsets the deleterious effects of germline ribosomopathy but increases opportunity for TP53-mutated cancer evolution.

Cell-free DNA measurable residual disease as a predictor of postallogeneic hematopoietic cell transplant outcomes

The measurable residual disease (MRD) assessment provides an attractive predictor of allogeneic hematopoietic cell transplnat (alloHCT) outcomes. Cell-free DNA (cfDNA) has been applied to diagnosis, early detection, and disease burden monitoring in various tumors, but its utility as an MRD test in myeloid malignancies has not been systematically evaluated. We sought to determine the differential sensitivity between bone marrow (BM) and cfDNA MRD and to assess the effect of cfDNA MRD on alloHCT outcomes. The technical and clinical validation cohorts, including 82 patients participating in clinical trials (Bone Marrow Transplant Clinical Trials Network-0201 and 0402), were used. Ultradeep error-corrected targeted sequencing was performed on plasma and BM-derived DNA. We demonstrated that 94.6% (range, 93.9-95.3) of cfDNA was derived from hematopoietic tissue. The mutant allele fraction was congruent between BM and cfDNA (rho = 0.8; P < .0001); however, cfDNA seemed to be more sensitive in detecting clones with a variant allele frequency (VAF) of <0.26%. cfDNA-MRD clearance by day 90 after alloHCT (D90) was associated with improved relapse-free survival (RFS, median survival not reached vs 5.5 months; P < .0001) and overall survival (OS, median survival not reached vs 7.3 months; P < .0001) when compared with patients with persistent MRD. Irrespective of pre-alloHCT MRD, D90 cfDNA MRD was associated with inferior 2-year OS (16.7% vs 84.8%; P < .0001) and RFS (16.7% vs 80.7%; P < .0001). cfDNA seems to be an accurate, minimally invasive alternative to BM aspirates in MRD assessment and confers important prognostic implications in patients with myeloid malignancies undergoing alloHCT.

Moving toward a conceptualization of measurable residual disease in myelodysplastic syndromes

Approximately 90% of patients with myelodysplastic syndromes (MDSs) have somatic mutations that are known or suspected to be oncogenic in the malignant cells. The genetic risk stratification of MDSs has evolved substantially with the introduction of the clinical molecular international prognostic scoring system, which establishes next-generation sequencing at diagnosis as a standard of care. Furthermore, the International Consensus Classification of myeloid neoplasms and acute leukemias has refined the MDS diagnostic criteria with the introduction of a new MDS/acute myeloid leukemia category. Monitoring measurable residual disease (MRD) has historically been used to define remission status, improve relapse prediction, and determine the efficacy of antileukemic drugs in patients with acute and chronic leukemias. However, in contrast to leukemias, assessment of MRD, including tracking of patient-specific mutations, has not yet been formally defined as a biomarker for MDS. This article summarizes current evidence and challenges and provides a conceptual framework for incorporating MRD into the treatment of MDS and future clinical trials.

Prevalence and clinical expression of germ line predisposition to myeloid neoplasms in adults with marrow hypocellularity

Systematic studies of germ line genetic predisposition to myeloid neoplasms in adult patients are still limited. In this work, we performed germ line and somatic targeted sequencing in a cohort of adult patients with hypoplastic bone marrow (BM) to study germ line predisposition variants and their clinical correlates. The study population included 402 consecutive adult patients investigated for unexplained cytopenia and reduced age-adjusted BM cellularity. Germ line mutation analysis was performed using a panel of 60 genes, and variants were interpreted per the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines; somatic mutation analysis was performed using a panel of 54 genes. Of the 402 patients, 27 (6.7%) carried germ line variants that caused a predisposition syndrome/disorder. The most frequent disorders were DDX41-associated predisposition, Fanconi anemia, GATA2-deficiency syndrome, severe congenital neutropenia, RASopathy, and Diamond-Blackfan anemia. Eighteen of 27 patients (67%) with causative germ line genotype were diagnosed with myeloid neoplasm, and the remaining with cytopenia of undetermined significance. Patients with a predisposition syndrome/disorder were younger than the remaining patients and had a higher risk of severe or multiple cytopenias and advanced myeloid malignancy. In patients with myeloid neoplasm, causative germ line mutations were associated with increased risk of progression into acute myeloid leukemia. Family or personal history of cancer did not show significant association with a predisposition syndrome/disorder. The findings of this study unveil the spectrum, clinical expressivity, and prevalence of germ line predisposition mutations in an unselected cohort of adult patients with cytopenia and hypoplastic BM.

Correlation analysis between auto-immunological and mutational profiles in myelodysplastic syndromes

OBJECTIVE AND DESIGN

Systemic-Inflammatory-Autoimmune-Diseases (SIAD) is increasingly considered in Myelodysplastic-Syndromes (MDS). In this line, we evaluated the MDS auto-immunological profile, correlating it to the mutational landscape, trying to identify a molecular-genetic trigger agent related to SIAD.

METHODS AND MATERIALS

Eighty-one MDS were enrolled and t-NGS was performed. Anti-Nuclear-Antibodies (ANA) were tested, and ANA-antigenic-specificity was characterized by ANA-profile, ENA-screen, anti-dsDNA. Non-Hematological-Patients (NHP) and Healthy-Donors (HD) were used as controls.

RESULTS

At clinically relevant cut-off (≥ 1:160), ANA was significantly more frequent in MDS, while ANA-antigenic-specificity showed a low association rate. ANA ≥ 1:160-positive MDS showed a mutational landscape similar to ANA-negative/ANA < 1:160 MDS. No significant correlations between mutational and immunological profiles were found and UBA1 mutations, related to VEXAS, were absent.

CONCLUSIONS

Although ANA-positivity was found to be increased in MDS, the low ANA-antigenic-specificity suggests that autoantibodies didn't recognize autoimmune-pathognomonic antigens. The lack of relationship between genetic profile and ANA-positivity, suggests that MDS genetic variants may not be the direct cause of SIAD.

Postazacitidine clone size predicts long-term outcome of patients with myelodysplastic syndromes and related myeloid neoplasms

Azacitidine is a mainstay of therapy for myelodysplastic syndrome (MDS)-related diseases. The purpose of our study is to elucidate the effect of gene mutations on hematological response and overall survival (OS), particularly focusing on their posttreatment clone size. We enrolled a total of 449 patients with MDS or related myeloid neoplasms. They were analyzed for gene mutations in pretreatment (n = 449) and posttreatment (n = 289) bone marrow samples using targeted-capture sequencing to assess the impact of gene mutations and their posttreatment clone size on treatment outcomes. In Cox proportional hazard modeling, multihit TP53 mutation (hazard ratio [HR], 2.03; 95% confidence interval [CI], 1.42-2.91; P < .001), EZH2 mutation (HR, 1.71; 95% CI, 1.14-2.54; P = .009), and DDX41 mutation (HR, 0.33; 95% CI, 0.17-0.62; P < .001), together with age, high-risk karyotypes, low platelets, and high blast counts, independently predicted OS. Posttreatment clone size accounting for all drivers significantly correlated with International Working Group (IWG) response (P < .001, using trend test), except for that of DDX41-mutated clones, which did not predict IWG response. Combined, IWG response and posttreatment clone size further improved the prediction of the original model and even that of a recently proposed molecular prediction model, the molecular International Prognostic Scoring System (IPSS-M; c-index, 0.653 vs 0.688; P < .001, using likelihood ratio test). In conclusion, evaluation of posttreatment clone size, together with the pretreatment mutational profile as well as the IWG response play a role in better prognostication of azacitidine-treated patients with myelodysplasia.

Considerations for Drug Development in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) have historically been challenging diseases for drug development due to their biology, preclinical modeling, and the affected patient population. In April 2022, the FDA convened a panel of regulators and academic experts in MDS to discuss approaches to improve MDS drug development. The panel reviewed challenges in MDS clinical trial design and endpoints and outlined considerations for future trial design in MDS to facilitate drug development to meaningfully meet patient needs. Challenges for defining clinical benefit in patients with MDS include cumbersome response criteria, standardized transfusion thresholds, and application and validation of patient reported outcome instruments. Clinical trials should reflect the biology of disease evolution, the advanced age of patients with MDS, and how patients are treated in real-world settings to maximize the likelihood of identifying active drugs. In patients with lower-risk disease, response criteria for anemic patients should be based on baseline transfusion dependency, improvement in symptoms, and quality of life. For higher-risk patients with MDS, trials should include guidance to prevent dose reductions or delays that could limit efficacy, specify minimal durations of treatment (in the absence of toxicity or progression), and have endpoints focused on overall survival and durable responses. MDS trials should be designed from the outset to allow the practicable application of new therapies in this high-needs population, with drugs that can be administered and tolerated in community settings, and with endpoints that meaningfully improve patients' lives over existing therapies.

TP53-Mutated Myelodysplasia and Acute Myeloid Leukemia

TP53-mutated myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) form a distinct and heterogeneous group of myeloid malignancies associated with poor outcomes. Studies carried out in the last years have in part elucidated the complex role played by TP53 mutations in the pathogenesis of these myeloid disorders and in the mechanisms of drug resistance. A consistent number of studies has shown that some molecular parameters, such as the presence of a single or multiple TP53 mutations, the presence of concomitant TP53 deletions, the association with co-occurring mutations, the clonal size of TP53 mutations, the involvement of a single (monoallelic) or of both TP53 alleles (biallelic) and the cytogenetic architecture of concomitant chromosome abnormalities are major determinants of outcomes of patients. The limited response of these patients to standard treatments, including induction chemotherapy, hypomethylating agents and venetoclax-based therapies and the discovery of an immune dysregulation have induced a shift to new emerging therapies, some of which being associated with promising efficacy. The main aim of these novel immune and nonimmune strategies consists in improving survival and in increasing the number of TP53-mutated MDS/AML patients in remission amenable to allogeneic stem cell transplantation.

TP53 in AML and MDS: The new (old) kid on the block

MDS and AML are clonal hematopoietic stem cell disorders of increasing incidence, having a variable prognosis based, among others, on co-occurring molecular abnormalities. TP53 mutations are frequently detected in these myeloid neoplasms and portend a poor prognosis with known therapeutic resistance. This article provides a timely review of the complexity of TP53 alterations, providing updates in diagnosis and prognosis based on new 2022 International Consensus Classification (ICC) and World Health Organization (WHO) guidelines. The article addresses optimal testing strategies and reviews current and arising therapeutic approaches. While the treatment landscape for this molecular subgroup is under active development, further exploration is needed to optimize the care of this group of patients with unmet needs.

Why do we not have more drugs approved for MDS? A critical viewpoint on novel drug development in MDS

Approval of new agents to treat higher risk (HR) myelodysplastic syndrome (MDS) has stalled since the approval of DNA methyltransferase inhibitors (DNMTi). In addition, the options for patients with lower risk (LR) MDS who have high transfusion needs and do not harbor ring sideroblasts or 5q- syndrome are limited. Here, we review the current treatment landscape in MDS and identify areas of unmet need, such as treatment after failure of erythropoiesis-stimulating agents or DNMTis, TP53-mutated disease, and MDS with potentially targetable mutations. We discuss how our understanding of MDS pathogenesis can inform therapy development, including treating HR-MDS similarly to AML and pursuing therapies to address splicing factor mutations and dysregulated inflammation. We then bring a critical lens to current methodology of MDS studies and propose solutions to improve the efficiency and yield of these clinical trials, including using the most meaningful response metrics and expanding enrollment.

Biallelic disruption of DDX41 activity is associated with distinct genomic and immunophenotypic hallmarks in acute leukemia

Introduction

Inherited DDX41 mutations cause familial predisposition to hematologic malignancies including acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), with the majority of DDX41 mutated MDS/AMLs described to date harboring germline DDX41 and co-occurring somatic DDX41 variants. DDX41-AMLs were shown to share distinguishing clinical features such as a late AML onset and an indolent disease associated with a favorable outcome. However, genotype-phenotype correlation in DDX41-MDS/AMLs remain poorly understood.

Methods

Here, we studied the genetic profile, bone marrow morphology and immunophenotype of 51 patients with DDX41 mutations. We further assessed the functional impact of ten previously uncharacterized DDX41 variants of uncertain significance.

Results

Our results demonstrate that MDS/AML cases harboring two DDX41 variants share specific clinicopathologic hallmarks that are not seen in other patients with monoallelic DDX41 related hematologic malignancies. We further showed that the features seen in these individuals with two DDX41 variants were concordant with biallelic DDX41 disruption.

Discussion

Here, we expand on previous clinicopathologic findings on DDX41 mutated hematologic malignancies. Functional analyses conducted in this study unraveled previously uncharacterized DDX41 alleles and further illustrate the implication of biallelic disruption in the pathophysiology of this distinct AML entity.

RNA splicing factor Rbm25 underlies heterogeneous preleukemic clonal expansion in mice

Clonal expansion sets the stage for cancer genesis by allowing for the accumulation of molecular alterations. Although genetic mutations such as Tet2 that induce clonal expansion and malignancy have been identified, these mutations are also frequently found in healthy individuals. Here, we tracked preleukemic clonal expansion using genetic barcoding in an inducible Tet2 knockout mouse model and found that only a small fraction of hematopoietic stem cells (HSCs) expanded excessively upon Tet2 knockout. These overexpanded HSCs expressed significantly lower levels of genes associated with leukemia and RNA splicing than nonoverexpanded Tet2 knockout HSCs. Knocking down Rbm25, an identified RNA splicing factor, accelerated the expansion of Tet2-knockout hematopoietic cells in vitro and in vivo. Our data suggest that mutations of an epigenetic factor Tet2 induce variability in the expression of an RNA splicing factor Rbm25, which subsequently drives heterogeneous preleukemic clonal expansion. This heterogeneous clonal expansion could contribute to the variable disease risks across individuals.

Impact of TP53 on outcome of patients with myelofibrosis undergoing hematopoietic stem cell transplantation

TP53 mutations (TP53MTs) have been associated with poor outcomes in various hematologic malignancies, but no data exist regarding its role in patients with myelofibrosis undergoing hematopoietic stem cell transplantation (HSCT). Here, we took advantage of a large international multicenter cohort to evaluate the role of TP53MT in this setting. Among 349 included patients, 49 (13%) had detectable TP53MT, of whom 30 showed a multihit configuration. Median variant allele frequency was 20.3%. Cytogenetic risk was favorable (71%), unfavorable (23%), and very high (6%), with complex karyotype present in 36 patients (10%). Median survival of patients with TP53MT was 1.5 vs 13.5 years for those with wild-type TP53 (TP53WT; P < .001). Outcome was driven by multihit TP53MT constellation (P < .001), showing 6-year survival of 56% for individuals with single-hit vs 25% for those with multihit TP53MT vs 64% for those with TP53WT. Outcome was independent of current transplantation-specific risk factors and conditioning intensity. Similarly, cumulative incidence of relapse was 17% for single-hit vs 52% for multihit vs 21% for TP53WT. Ten patients with TP53MT (20%) presented as leukemic transformation vs only 7 (2%) in the TP53WT group (P < .001). Out of the 10 patients with TP53MT, 8 showed multihit constellation. Median time to leukemic transformation was shorter for multihit and single-hit TP53MT (0.7 and 0.5 years, respectively) vs 2.5 years for TP53WT. In summary, multihit TP53MT represents a very high-risk group in patients with myelofibrosis who are undergoing HSCT, whereas single-hit TP53MT alone showed similar outcome to patients with nonmutated TP53, informing prognostication for survival and relapse together with current transplantation-specific tools.

Real-World Validation of Molecular International Prognostic Scoring System for Myelodysplastic Syndromes

PURPOSE

Myelodysplastic syndromes (MDS) are heterogeneous myeloid neoplasms in which a risk-adapted treatment strategy is needed. Recently, a new clinical-molecular prognostic model, the Molecular International Prognostic Scoring System (IPSS-M) was proposed to improve the prediction of clinical outcome of the currently available tool (Revised International Prognostic Scoring System [IPSS-R]). We aimed to provide an extensive validation of IPSS-M.

METHODS

A total of 2,876 patients with primary MDS from the GenoMed4All consortium were retrospectively analyzed.

RESULTS

IPSS-M improved prognostic discrimination across all clinical end points with respect to IPSS-R (concordance was 0.81 v 0.74 for overall survival and 0.89 v 0.76 for leukemia-free survival, respectively). This was true even in those patients without detectable gene mutations. Compared with the IPSS-R based stratification, the IPSS-M risk group changed in 46% of patients (23.6% and 22.4% of subjects were upstaged and downstaged, respectively).In patients treated with hematopoietic stem cell transplantation (HSCT), IPSS-M significantly improved the prediction of the risk of disease relapse and the probability of post-transplantation survival versus IPSS-R (concordance was 0.76 v 0.60 for overall survival and 0.89 v 0.70 for probability of relapse, respectively). In high-risk patients treated with hypomethylating agents (HMA), IPSS-M failed to stratify individual probability of response; response duration and probability of survival were inversely related to IPSS-M risk.Finally, we tested the accuracy in predicting IPSS-M when molecular information was missed and we defined a minimum set of 15 relevant genes associated with high performance of the score.

CONCLUSION

IPSS-M improves MDS prognostication and might result in a more effective selection of candidates to HSCT. Additional factors other than gene mutations can be involved in determining HMA sensitivity. The definition of a minimum set of relevant genes may facilitate the clinical implementation of the score.

Toward a systems-level probing of tumor clonality

Cancer has been described as a genetic disease that clonally evolves in the face of selective pressures imposed by cell-intrinsic and extrinsic factors. Although classical models based on genetic data predominantly propose Darwinian mechanisms of cancer evolution, recent single-cell profiling of cancers has described unprecedented heterogeneity in tumors providing support for alternative models of branched and neutral evolution through both genetic and non-genetic mechanisms. Emerging evidence points to a complex interplay between genetic, non-genetic, and extrinsic environmental factors in shaping the evolution of tumors. In this perspective, we briefly discuss the role of cell-intrinsic and extrinsic factors that shape clonal behaviors during tumor progression, metastasis, and drug resistance. Taking examples of pre-malignant states associated with hematological malignancies and esophageal cancer, we discuss recent paradigms of tumor evolution and prospective approaches to further enhance our understanding of this spatiotemporally regulated process.

Clonal hematopoiesis and bone marrow inflammation

Clonal hematopoiesis (CH) occurs in hematopoietic stem cells with increased risks of progressing to hematologic malignancies. CH mutations are predominantly found in aged populations and correlate with an increased incidence of cardiovascular and other diseases. Increased lines of evidence demonstrate that CH mutations are closely related to the inflammatory bone marrow microenvironment. In this review, we summarize the recent advances in this topic starting from the discovery of CH and its mutations. We focus on the most commonly mutated and well-studied genes in CH and their contributions to the innate immune responses and inflammatory signaling, especially in the hematopoietic cells of bone marrow. We also aimed to discuss the interrelationship between inflammatory bone marrow microenvironment and CH mutations. Finally, we provide our perspectives on the challenges in the field and possible future directions to help understand the pathophysiology of CH.

CHIP Happens: Clonal Hematopoiesis of Indeterminate Potential and Its Relationship to Solid Tumors

Clonal hematopoiesis of indeterminate potential (CHIP) is characterized by the expansion of hematopoietic cells harboring leukemia-associated somatic mutations in otherwise healthy people and occurs in at least 10% of adults over 70. It is well established that people with CHIP have increased rates of hematologic malignancy, increased risk of cardiovascular disease, and worse all-cause mortality compared with those without CHIP. Despite recent advancements in understanding CHIP as it relates to these known outcomes, much remains to be learned about the development and role of CHIP in other disease states. Emerging research has identified high rates of CHIP in patients with solid tumors, driven in part by oncologic therapy, and revealed associations between CHIP and differential outcomes in both solid tumors and other diseases. Recent studies have demonstrated that CHIP can contribute to dysregulated inflammatory signaling in multiple contexts, underscoring the importance of interrogating how CHIP might alter tumor immunology. Here, we review the role of CHIP mutations in clonal expansion of hematopoietic cells, explore the relationship between CHIP and solid tumors, and discuss the potential roles of CHIP in inflammation and solid tumor biology.

TP53 Alterations in Myelodysplastic Syndromes and Acute Myeloid Leukemia

TP53 mutations are less frequent in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) than in solid tumors, except in secondary and therapy-related MDS/AMLs, and in cases with complex monosomal karyotype. As in solid tumors, missense mutations predominate, with the same hotspot mutated codons (particularly codons 175, 248, 273). As TP53-mutated MDS/AMLs are generally associated with complex chromosomal abnormalities, it is not always clear when TP53 mutations occur in the pathophysiological process. It is also uncertain in these MDS/AML cases, which often have inactivation of both TP53 alleles, if the missense mutation is only deleterious through the absence of a functional p53 protein, or through a potential dominant-negative effect, or finally a gain-of-function effect of mutant p53, as demonstrated in some solid tumors. Understanding when TP53 mutations occur in the disease course and how they are deleterious would help to design new treatments for those patients who generally show poor response to all therapeutic approaches.

TP53 mutation variant allele frequency of ≥10% is associated with poor prognosis in therapy-related myeloid neoplasms

Revised diagnostic criteria for myeloid neoplasms (MN) issued by the International Consensus Classification (ICC) and the World Health Organization (WHO) recommended major change pertaining to TP53-mutated (TP53mut) MN. However, these assertions have not been specifically examined in therapy-related myeloid neoplasm (t-MN), a subset enriched with TP53mut. We analyzed 488 t-MN patients for TP53mut. At least one TP53mut with variant allele frequency (VAF) ≥ 2% with or without loss of TP53 locus was noted in 182 (37.3%) patients and 88.2% of TP53mut t-MN had a VAF ≥10%. TP53mut t-MN with VAF ≥ 10% had a distinct clinical and biological profile compared to both TP53mut VAF < 10% and wild-type TP53 (TP53wt) cases. Notably, TP53mut VAF ≥ 10% had a significantly shorter survival compared to TP53wt (8.3 vs. 21.6 months; P < 0.001), while the survival of TP53mut VAF < 10% was comparable to TP53wt. Within TP53mut VAF ≥ 10% cohort, the inferior outcomes persisted irrespective of the single- or multi-hit status, co-mutation pattern, or treatments received. Finally, survival of TP53mut patients was poor across all the blast categories and MDS patients with >10% blasts had inferior survival compared to <5%. In summary, TP53mut VAF ≥10% signified a clinically and molecularly homogenous cohort regardless of the allelic status.

Overcoming relapse: prophylactic or pre-emptive use of azacitidine or FLT3 inhibitors after allogeneic transplantation for AML or MDS

Relapse remains the most critical obstacle in treatment by allogeneic hematopoietic stem cell transplantation (HSCT). Non-relapse mortality has improved annually, but relapse mortality remains high. Post-transplant maintenance treatment, such as hypomethylating agents and FMS-like tyrosine kinase 3 (FLT3) inhibitors, has been investigated for decades as a means of preventing disease relapse after HSCT. Other factors besides the relapse tendency of the primary disease that can affect the transition of estimated disease burden in patients undergoing HSCT are disease status at HSCT (non-remission, remission with minimal/measurable residual disease (MRD), and remission without MRD) and conditioning regimen intensity. Optimal selection of patients at high risk for relapse who can tolerate a long duration of therapy is pivotal for successful post-transplant maintenance therapy. In this review, we provide an overview of current progress in research on post-transplant maintenance treatment using azacitidine or FLT3 inhibitors for preventing disease relapse after HSCT for AML or MDS, and discuss the future outlook in this area.

Predisposition to myeloid malignancies in Shwachman-Diamond syndrome: biological insights and clinical advances

Shwachman-Diamond syndrome (SDS) is an inherited multisystem ribosomopathy characterized by exocrine pancreatic deficiency, bone marrow failure, and predisposition to myeloid malignancies. The pathobiology of SDS results from impaired ribosomal maturation due to the deficiency of SBDS and the inability to evict the antiassociation factor eIF6 from the 60S ribosomal subunit. Clinical outcomes for patients with SDS who develop myeloid malignancies are extremely poor because of high treatment-related toxicities and a high rate of refractory disease/relapse even after allogeneic hematopoietic stem cell transplant (HSCT). Registry data indicate that outcomes are improved for patients with SDS who undergo routine bone marrow surveillance and receive an HSCT before developing an overt malignancy. However, the optimal approach to hematologic surveillance and the timing of HSCT for patients with SDS is not clearly established. Recent studies have elucidated distinct patterns of somatic blood mutations in patients with SDS that either alleviate the ribosome defect via somatic rescue (heterozygous EIF6 inactivation) or disrupt cellular checkpoints, resulting in increased leukemogenic potential (heterozygous TP53 inactivation). Genomic analysis revealed that most myeloid malignancies in patients with SDS have biallelic loss-of-function TP53 mutations. Single-cell DNA sequencing of SDS bone marrow samples can detect premalignant biallelic TP53-mutated clones before clinical diagnosis, suggesting that molecular surveillance may enhance the detection of incipient myeloid malignancies when HSCT may be most effective. Here, we review the clinical, genetic, and biologic features of SDS. In addition, we present evidence supporting the hematologic surveillance for patients with SDS that incorporates clinical, pathologic, and molecular data to risk stratify patients and prioritize transplant evaluation for patients with SDS with high-risk features.

The Genetic Landscape of Myelodysplastic Neoplasm Progression to Acute Myeloid Leukemia

Myelodysplastic neoplasm (MDS) represents a heterogeneous group of myeloid disorders that originate from the hematopoietic stem and progenitor cells that lead to the development of clonal hematopoiesis. MDS was characterized by an increased risk of transformation into acute myeloid leukemia (AML). In recent years, with the aid of next-generation sequencing (NGS), an increasing number of molecular aberrations were discovered, such as recurrent mutations in FLT3, NPM1, DNMT3A, TP53, NRAS, and RUNX1 genes. During MDS progression to leukemia, the order of gene mutation acquisition is not random and is important when considering the prognostic impact. Moreover, the co-occurrence of certain gene mutations is not random; some of the combinations of gene mutations seem to have a high frequency (ASXL1 and U2AF1), while the co-occurrence of mutations in splicing factor genes is rarely observed. Recent progress in the understanding of molecular events has led to MDS transformation into AML and unraveling the genetic signature has paved the way for developing novel targeted and personalized treatments. This article reviews the genetic abnormalities that increase the risk of MDS transformation to AML, and the impact of genetic changes on evolution. Selected therapies for MDS and MDS progression to AML are also discussed.

Prognostic landscape of mitochondrial genome in myelodysplastic syndrome after stem-cell transplantation

Despite mitochondrial DNA (mtDNA) mutations are common events in cancer, their global frequency and clinical impact have not been comprehensively characterized in patients with myelodysplastic neoplasia (also known as myelodysplastic syndromes, MDS). Here we performed whole-genome sequencing (WGS) on samples obtained before allogenic hematopoietic cell transplantation (allo-HCT) from 494 patients with MDS who were enrolled in the Center for International Blood and Marrow Transplant Research. We evaluated the impact of mtDNA mutations on transplantation outcomes, including overall survival (OS), relapse, relapse-free survival (RFS), and transplant-related mortality (TRM). A random survival forest algorithm was applied to evaluate the prognostic performance of models that include mtDNA mutations alone and combined with MDS- and HCT-related clinical factors. A total of 2666 mtDNA mutations were identified, including 411 potential pathogenic variants. We found that overall, an increased number of mtDNA mutations was associated with inferior transplantation outcomes. Mutations in several frequently mutated mtDNA genes (e.g., MT-CYB and MT-ND5) were identified as independent predictors of OS, RFS, relapse and/or TRM after allo-HCT. Integration of mtDNA mutations into the models based on the Revised International Prognostic Scores (IPSS-R) and clinical factors related to MDS and allo-HCT could capture more prognostic information and significantly improve the prognostic stratification efforts. Our study represents the first WGS effort in MDS receiving allo-HCT and shows that there may be clinical utility of mtDNA variants to predict allo-HCT outcomes in combination with more standard clinical parameters.

TP53 mutations are associated with increased infections and reduced hematopoietic cell transplantation rates in myelodysplastic syndrome and acute myeloid leukemia

BACKGROUND

Although allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for patients with poor-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), only a minority of these patients undergo HCT. TP53-mutated (TP53^MUT) MDS/AML is particularly high risk, yet fewer TP53^MUT patients undergo HCT than other poor-risk TP53-wild type (TP53^WT) patients.

OBJECTIVE

We hypothesized that TP53^MUT MDS/AML patients have unique risk factors affecting rates of HCT, and therefore investigated phenotypic changes that may prevent patients with TP53^MUT MDS/AML from receiving HCT.

STUDY DESIGN

This study was a single center retrospective analysis of outcomes for adults with newly diagnosed MDS or AML (n=352). HLA typing was used as a surrogate for physician "intent to transplant." Multivariable logistic regression models were used to estimate odds ratios (OR) for factors associated with HLA typing, HCT, and pre-transplant infections. Multivariable Cox proportional hazards models were used to create predicted survival curves for patients with and without TP53 mutations.

RESULTS

Overall significantly fewer TP53^MUT patients underwent HCT compared to TP53^WT patients (19% versus 31%, p=0.028). Development of an infection was significantly associated with decreased odds of HCT (OR=0.42, 95% CI: 0.19-0.90) and worse overall survival (HR=1.46, 95% CI: 1.09-1.96) in multivariable analyses. TP53^MUT disease was independently associated with increased odds of developing an infection (OR 2.18, 95% CI: 1.21-3.93), bacterial pneumonia (OR 1.83, 95% CI: 1.00-3.33), and invasive fungal infection (OR 2.64, 95% CI: 1.34-5.22) prior to HCT. Infections were the cause of death in significantly more patients with TP53^MUT disease (38% vs 19%, p=0.005).

CONCLUSIONS

With substantially more infections and decreased HCT rates in patients with TP53 mutations, this raises the possibility that phenotypic changes occurring in TP53^MUT disease may affect infection susceptibility in this population and drastically impact clinical outcomes.

Understanding the Continuum between High-Risk Myelodysplastic Syndrome and Acute Myeloid Leukemia

Myelodysplastic syndrome (MDS) is a clonal hematopoietic neoplasm characterized by bone marrow dysplasia, failure of hematopoiesis and variable risk of progression to acute myeloid leukemia (AML). Recent large-scale studies have demonstrated that distinct molecular abnormalities detected at earlier stages of MDS alter disease biology and predict progression to AML. Consistently, various studies analyzing these diseases at the single-cell level have identified specific patterns of progression strongly associated with genomic alterations. These pre-clinical results have solidified the conclusion that high-risk MDS and AML arising from MDS or AML with MDS-related changes (AML-MRC) represent a continuum of the same disease. AML-MRC is distinguished from de novo AML by the presence of certain chromosomal abnormalities, such as deletion of 5q, 7/7q, 20q and complex karyotype and somatic mutations, which are also present in MDS and carry crucial prognostic implications. Recent changes in the classification and prognostication of MDS and AML by the International Consensus Classification (ICC) and the World Health Organization (WHO) reflect these advances. Finally, a better understanding of the biology of high-risk MDS and the mechanisms of disease progression have led to the introduction of novel therapeutic approaches, such as the addition of venetoclax to hypomethylating agents and, more recently, triplet therapies and agents targeting specific mutations, including FLT3 and IDH1/2. In this review, we analyze the pre-clinical data supporting that high-risk MDS and AML-MRC share the same genetic abnormalities and represent a continuum, describe the recent changes in the classification of these neoplasms and summarize the advances in the management of patients with these neoplasms.

Molecular characterization and prognosis of mutant TP53 acute myeloid leukemia and myelodysplastic syndrome with excess blasts

INTRODUCTION

Myeloid tumors typically harbor TP53 mutations, which are linked to a dismal prognosis. There are fewer studies on whether TP53-mutated acute myeloid leukemia (AML) and myelodysplastic syndrome with excess blasts (MDS-EB) differ in molecular characteristics and should be considered as separate entities.

METHODS

Between January 2016 and December 2021, a retrospective analysis was done on a total of 73 newly diagnosed AML patients and 61 MDS-EB patients from the first affiliated hospital of Soochow University. We described a survival profile and a thorough characterization of newly found TP53-mutant AML and MDS-EB and investigated the relationship between these characteristics and overall survival (OS).

RESULTS

38 (31.1%) were mono-allelic, and 84 (68.9%) were bi-allelic. There is no significant difference between TP53-mutated AML and MDS-EB (median OS 12.9 verse 14.4 months; p = .558). Better overall survival was linked to mono-allelic TP53 than bi-allelic TP53(HR = 3.030, CI:1.714-5.354, p < .001). However, the number of TP53 mutations and comutations were not significantly associated with OS. TP53 variant allele frequency cutoff of 50% is significant correlation with OS (HR: 2.177, 95% CI: 1.142-4.148; p = .0063).

CONCLUSION

Our data revealed that allele status and allogeneic hematopoietic stem cell transplant independently affect the prognostic of AML and MDS-EB patients, with a concordance of molecular features and survival between these two disease entities. Our analysis favors considering TP53-mutated AML/MDS-EB as a distinct disorder.

Oncogenic RAS promotes leukemic transformation of CUX1-deficient cells

-7/del(7q) is prevalent across subtypes of myeloid neoplasms. CUX1, located on 7q22, encodes a homeodomain-containing transcription factor, and, like -7/del(7q), CUX1 inactivating mutations independently carry a poor prognosis. As with loss of 7q, CUX1 mutations often occur early in disease pathogenesis. We reported that CUX1 deficiency causes myelodysplastic syndrome in mice but was insufficient to drive acute myeloid leukemia (AML). Given the known association between -7/del(7q) and RAS pathway mutations, we mined cancer genome databases and explicitly linked CUX1 mutations with oncogenic RAS mutations. To determine if activated RAS and CUX1 deficiency promote leukemogenesis, we generated mice bearing NrasG12D and CUX1-knockdown which developed AML, not seen in mice with either mutation alone. Oncogenic RAS imparts increased self-renewal on CUX1-deficient hematopoietic stem/progenitor cells (HSPCs). Reciprocally, CUX1 knockdown amplifies RAS signaling through reduction of negative regulators of RAS/PI3K signaling. Double mutant HSPCs were responsive to PIK3 or MEK inhibition. Similarly, low expression of CUX1 in primary AML samples correlates with sensitivity to the same inhibitors, suggesting a potential therapy for malignancies with CUX1 inactivation. This work demonstrates an unexpected convergence of an oncogene and tumor suppressor gene on the same pathway.

A Lower Frequency of Spliceosome Mutations Distinguishes Clonal Cytopenias of Undetermined Significance From Low-Risk Myelodysplastic Syndromes, Despite Inherent Similarities in Genomic, Laboratory, and Clinical Features

Clonal cytopenias of undetermined significance (CCUS) are associated with an increased risk of developing a myelodysplastic syndrome (MDS); however, the mechanism and factors associated with evolution remain unclear. We propose that next-generation sequencing (NGS) of cytopenic cases with equivocal morphologic dysplasia will improve patient clinical care and that serial sequencing of such equivocal cases could identify the factors that predict evolution to MDS. We performed targeted NGS of samples from 193 individuals with confirmed or suspected MDS or MDS/myeloproliferative neoplasm, including sequential investigation for 28 individuals at the time of diagnosis and during follow-up. NGS facilitated the diagnosis of all suspicious cases as myeloid neoplasm (21%), CCUS (34%), or idiopathic cytopenias of undetermined significance (45%) when no variants were detected. We found that there was no significant difference in most measured clinical features or clonal phenotypes, such as cell counts, number of variants, variant allele frequencies, and overall survival, between CCUS and International Prognostic Scoring System-Revised-defined low-risk MDS. However, there was a significant difference in the types of variants between CCUS and low-risk MDS, with a significantly lower number of splicing factor mutations in CCUS cases (P < .001). Moreover, we observed an increased probability of evolution to MDS of individuals with CCUS compared with that in those with idiopathic cytopenias of undetermined significance over the first 5 years (P = .045). Our analyses revealed no conclusive pattern associating clonal expansion or the number of variants with the evolution of CCUS to MDS, perhaps further supporting the similarity of these diseases and the clinical importance of recognizing and formally defining CCUS as a category of precursor myeloid disease state in the next revision of the World Health Organization guidelines.

TP53-altered higher-risk myelodysplastic syndromes/neoplasms and acute myeloid leukemia: a distinct genetic entity with unique unmet needs

Pathogenic alterations of TP53 are an independent poor prognostic factor in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Clinical course of TP53- altered myeloid neoplasms is dictated by genetic characteristics, such as TP53 allelic state and variant allele frequency (VAF), and not the blast count. Hence, it was recently proposed that MDS (with increased blasts) and AML with TP53 alterations may be best classified as a single molecular disease entity, TP53-mutated higher-risk (HR)-MDS/AML. TP53 mutations drive resistance to intensive chemotherapies and less intensive hypomethylating agents (HMA). Novel combinations incorporating BCL2 inhibitor venetoclax improve response rates for TP53-mutated subgroup, but the survival is not improved. Early clinical studies combining HMA with investigational agents demonstrated activity in TP53-mutated HR-MDS/AML, but updated results with larger samples, longer follow-up, or randomized trials were less impressive to date. Future research should focus on finding novel, potentially disease-modifying therapies to improve outcomes in patients with TP53-mutated HR-MDS/AML.

Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008, and 2016 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic, and molecular advances have been made in the field of myeloid neoplasms, which have contributed to refine diagnostic criteria, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classification proposals of myeloid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with a focus on adult myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML). The goal is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of these hematological malignancies.

The effect of granulocyte-colony stimulating factor, decitabine, and busulfan-cyclophosphamide versus busulfan-cyclophosphamide conditioning on relapse in patients with myelodysplastic syndrome or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic haematopoietic stem-cell transplantation: an open-label, multicentre, randomised, phase 3 trial

BACKGROUND

Relapse remains high in patients with myelodysplastic syndrome-refractory anaemia with excess blasts (RAEB) or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic haematopoietic stem-cell transplantation (HSCT). We aimed to investigate whether granulocyte-colony stimulating factor (G-CSF) and decitabine plus busulfan-cyclophosphamide conditioning reduced relapse compared with busulfan-cyclophosphamide in this population.

METHODS

We did an open-label, randomised, phase 3 trial at six hospitals in China. Eligible patients (aged 14-65 years) had myelodysplastic syndrome-RAEB or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome, and an Eastern Cooperative Oncology Group performance status of 0-2 and HSCT comorbidity index of 0-2. Patients were randomly assigned (1:1) to receive G-CSF, decitabine, and busulfan-cyclophosphamide conditioning or busulfan-cyclophosphamide conditioning. Randomisation was done with permuted blocks (block size four) with no stratification and was implemented through an interactive web-based response system, which was independent of study site staff and investigators. G-CSF, decitabine, and busulfan-cyclophosphamide conditioning comprised G-CSF 5 μg/kg daily subcutaneously (days -17 to -10), decitabine 20 mg/m² daily intravenously (days -14 to -10), busulfan 3·2 mg/kg daily intravenously (days -7 to -4), and cyclophosphamide 60 mg/kg daily intravenously (days -3 and -2). Busulfan-cyclophosphamide conditioning comprised the same dose and duration of busulfan and cyclophosphamide. The primary endpoint was 2 year cumulative incidence of relapse. All efficacy and safety endpoints were assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02744742; the trial is complete.

FINDINGS

Between April 18, 2016, and Sept 30, 2019, 297 patients were screened for eligibility, 202 of whom were randomly assigned to G-CSF, decitabine, and busulfan-cyclophosphamide (n=101) or busulfan-cyclophosphamide (n=101) conditioning. 123 (61%) participants were male and 79 (31%) were female. Median follow-up was 32·4 months (IQR 10·0-43·0). The 2-year cumulative incidence of relapse was 10·9% (95% CI 5·8-17·9) in the G-CSF, decitabine, and busulfan-cyclophosphamide group and 24·8% (16·8-33·5) in the busulfan-cyclophosphamide group (hazard ratio 0·39 [95% CI 0·19-0·79]; p=0·011). Within 100 days after transplantation, the most common grade 3-4 adverse events in the G-CSF, decitabine, and busulfan-cyclophosphamide group and the busulfan-cyclophosphamide group were infections (34 [34%] and 32 [32%]), acute graft-versus-host disease (30 [30%] and 30 [30%]), and gastrointestinal toxicity (28 [28%] and 29 [29%]). 11 (11%) patients in the G-CSF, decitabine, and busulfan-cyclophosphamide group and 13 (13%) in the busulfan-cyclophosphamide group died of adverse events. There were no treatment related deaths.

INTERPRETATION

Our results suggest that G-CSF, decitabine, and busulfan-cyclophosphamide conditioning is a better choice than busulfan-cyclophosphamide conditioning for patients with myelodysplastic syndrome-RAEB or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic HSCT. This conditioning could be a suitable therapuetic option for this patient population.

FUNDING

None.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Survival of TP53-mutated acute myeloid leukemia patients receiving allogeneic stem cell transplantation after first induction or salvage therapy: results from the Consortium on Myeloid Malignancies and Neoplastic Diseases (COMMAND)

We conducted a multi-center study to analyze factors predicting survival among patients with TP53-mutated (m) AML receiving allogeneic hematopoietic stem cell transplant (allo-HSCT) in the recent era. Out of 370 TP53m AML patients, 68 (18%) patients were bridged to allo-HSCT. The median age of the patients was 63 years (range, 33-75), 82% of patients had complex cytogenetics and 66% of patients had multi-hit TP53m. Forty three percent received myeloablative conditioning and 57% received reduced intensity conditioning. The incidence of acute graft versus host disease (GVHD) was 37% and chronic GVHD was 44%. The median event-free survival (EFS) from the time of allo-HSCT was 12.4 months (95% CI: 6.24-18.55) and median overall survival (OS) was 24.5 months (95% CI: 21.80-27.25). In multivariate analysis utilizing variables that showed significance in univariate analysis, complete remission at day 100 post allo-HSCT retained significance for EFS (HR: 0.24, 95% CI: 0.10-0.57, p = 0.001) and OS (HR: 0.22, 95% CI: 0.10-0.50, p ≤ 0.001). Similarly, occurrence of chronic GVHD retained significance for EFS (HR: 0.21, 95% CI: 0.09-0.46, p ≤ 0.001) and OS (HR: 0.34, 95% CI: 0.15-0.75, p = 0.007). Our report suggests that allo-HSCT offers the best opportunity to improve long-term outcome among patients with TP53m AML.

Impact of gene alterations on clinical outcome in young adults with myelodysplastic syndromes

Young adults with myelodysplastic syndrome (MDS) are rare, and the clinical significance of driver mutations has not yet been analysed. We analysed the gene mutations and copy number alterations (CNAs) in younger MDS patients using next-generation sequencing, targeting 68 genes that were recurrently mutated in myeloid malignancies, to investigate the correlation between their genetic alterations and clinical outcomes. We enrolled 55 patients retrospectively (aged < 50 years). At least one mutation was detected in 56% of the patients. The most frequently mutated genes were ASXL1 and RUNX1, 13% each. We defined higher-risk patients as those with ≥ 2 mutations, except for SF3B1 mutation, and/or CNA. The 3-year overall survival (OS) in patients with a higher-risk was lower than that in those with a lower-risk (50.8% vs. 71.8%, P = 0.024). Among the 44 transplant recipients, patients with higher-risk had a significantly lower OS and tended to have a higher cumulative incidence of relapse (CIR) than those with a lower-risk (3-year OS: 38.0% vs. 64.4%, P = 0.039; 3-year CIR: 44.0% vs. 24.1%, P = 0.076). Our results showed that genetic aberrations can predict clinical outcomes in younger MDS patients, despite the low rate of genetic mutations.

The Immuno-Oncology and Genomic Aspects of DNA-Hypomethylating Therapeutics in Acute Myeloid Leukemia

Hypomethylating agents (HMAs) have been used for decades in the treatment of hematologic neoplasms, and now, have gathered attention again in terms of their combination with potent molecular-targeted agents such as a BCL-6 inhibitor venetoclax and an IDH1 inhibitor ivosidenib, as well as a novel immune-checkpoint inhibitor (anit-CD47 antibody) megrolimab. Several studies have shown that leukemic cells have a distinct immunological microenvironment, which is at least partially due to genetic alterations such as the TP53 mutation and epigenetic dysregulation. HMAs possibly improve intrinsic anti-leukemic immunity and sensitivity to immune therapies such as PD-1/PD-L1 inhibitors and anti-CD47 agents. This review describes the immuno-oncological backgrounds of the leukemic microenvironment and the therapeutic mechanisms of HMAs, as well as current clinical trials of HMAs and/or venetoclax-based combination therapies.

Germ line DDX41 mutations define a unique subtype of myeloid neoplasms

Germ line DDX41 variants have been implicated in late-onset myeloid neoplasms (MNs). Despite an increasing number of publications, many important features of DDX41-mutated MNs remain to be elucidated. Here we performed a comprehensive characterization of DDX41-mutated MNs, enrolling a total of 346 patients with DDX41 pathogenic/likely-pathogenic (P/LP) germ line variants and/or somatic mutations from 9082 MN patients, together with 525 first-degree relatives of DDX41-mutated and wild-type (WT) patients. P/LP DDX41 germ line variants explained ∼80% of known germ line predisposition to MNs in adults. These risk variants were 10-fold more enriched in Japanese MN cases (n = 4461) compared with the general population of Japan (n = 20 238). This enrichment of DDX41 risk alleles was much more prominent in male than female (20.7 vs 5.0). P/LP DDX41 variants conferred a large risk of developing MNs, which was negligible until 40 years of age but rapidly increased to 49% by 90 years of age. Patients with myelodysplastic syndromes (MDS) along with a DDX41-mutation rapidly progressed to acute myeloid leukemia (AML), which was however, confined to those having truncating variants. Comutation patterns at diagnosis and at progression to AML were substantially different between DDX41-mutated and WT cases, in which none of the comutations affected clinical outcomes. Even TP53 mutations made no exceptions and their dismal effect, including multihit allelic status, on survival was almost completely mitigated by the presence of DDX41 mutations. Finally, outcomes were not affected by the conventional risk stratifications including the revised/molecular International Prognostic Scoring System. Our findings establish that MDS with DDX41-mutation defines a unique subtype of MNs that is distinct from other MNs.

Identifying the optimal conditioning intensity for stem cell transplantation in patients with myelodysplastic syndrome: a machine learning analysis

A conditioning regimen is an essential prerequisite of allogeneic hematopoietic stem cell transplantation for patients with myelodysplastic syndrome (MDS). However, the optimal conditioning intensity for a patient may be difficult to establish. This study aimed to identify optimal conditioning intensity (reduced-intensity conditioning regimen [RIC] or myeloablative conditioning regimen [MAC]) for patients with MDS. Overall, 2567 patients with MDS who received their first HCT between 2009 and 2019 were retrospectively analyzed. They were divided into a training cohort and a validation cohort. Using a machine learning-based model, we developed a benefit score for RIC in the training cohort. The validation cohort was divided into a high-score and a low-score group, based on the median benefit score. The endpoint was progression-free survival (PFS). The benefit score for RIC was developed from nine baseline variables in the training cohort. In the validation cohort, the hazard ratios of the PFS in the RIC group compared to the MAC group were 0.65 (95% confidence interval [CI]: 0.48-0.90, P = 0.009) in the high-score group and 1.36 (95% CI: 1.06-1.75, P = 0.017) in the low-score group (P for interaction < 0.001). Machine-learning-based scoring can be useful for the identification of optimal conditioning regimens for patients with MDS.

Hematopoietic Cell Transplantation in the Management of Myelodysplastic Syndrome: An Evidence-Based Review from the American Society for Transplantation and Cellular Therapy Committee on Practice Guidelines

The sole curative therapy for myelodysplastic syndrome (MDS) is allogeneic hematopoietic cell transplantation (HCT). Here this therapeutic modality is reviewed and critically evaluated in the context of the evidence. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the recommendations. A panel of MDS experts comprising transplantation and nontransplantation physicians developed consensus treatment recommendations. This review summarizes the standard MDS indications for HCT and addresses areas of controversy. Recent prospective trials have confirmed that allogeneic HCT confers survival benefits in patients with advanced or high-risk MDS compared with nontransplantation approaches, and the use of HCT is increasing in older patients with good performance status. However, patients with high-risk cytogenetic or molecular mutations remain at high risk for relapse. It is unknown whether administration of novel therapies before or after transplantation may decrease the risk of disease relapse in selected populations. Ongoing and future studies will investigate revised approaches to disease risk stratification, patient selection, and post-transplantation approaches to optimize allogeneic HCT outcomes for patients with MDS.

Allogeneic stem cell transplantation for patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a heterogenous group of clonal hematopoietic stem cell neoplasms primarily affecting older persons, associated with dysplastic changes of bone marrow cells, peripheral cytopenias, and various risk of leukemic transformation. Although treatment with several drugs has shown improved disease control, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment for MDS. The number of patients receiving a transplant, as well as survival, have increased past years because of the use of reduce-intensity conditioning regimens (RIC) as well as the use of haploidentical donors for transplantation. With treatment-related mortality as main limitation, pre-transplant evaluation is essential to assess risks for this older group of patients. In a recent randomized study, allo-HSCT with RIC for patients >50 years old with higher-risk MDS demonstrated superiority in survival compared with hypomethylating agents. Genetic mutations have been shown to significantly impact treatment outcomes including after transplant. Recently, a transplant-specific risk score (which includes age, donor type, performance status, cytogenetic category, recipient's cytomegalovirus status, percentage of blasts, and platelet count) has shown superiority in transplantation outcome prediction, compared with previous scoring systems. Survival remains low for most patients with TP53 mutations and novel treatment strategies are needed, such as administration of natural killer cells post-transplant, as there is no clear evidence that maintenance therapy after transplantation can improve outcomes.

JAK2 Mutations Are Rare and Diverse in Myelodysplastic Syndromes: Case Series and Review of the Literature

OBJECTIVES

To investigate and characterize JAK2 mutations in myelodysplastic syndrome (MDS), we present three cases with diverse JAK2 mutations and review the literature.

METHODS

The institutional SoftPath software was used to find MDS cases between January 2020 and April 2022. The cases with a diagnosis of a myelodysplastic/myeloproliferative overlap syndrome including MDS/MPN with ring sideroblasts and thrombocytosis were excluded. The cases with molecular data by next generation sequencing looking for gene aberrations commonly seen in myeloid neoplasms were reviewed for the detection of JAK2 mutations including variants. A literature review on the identification, characterization, and significance of JAK2 mutations in MDS was performed.

RESULTS

Among 107 cases of the MDS reviewed, a JAK2 mutation was present in three cases, representing 2.8% of the overall cases. A JAK2 V617F mutation was found in one case representing slightly less than 1% of all the MDS cases. In addition, we found JAK2 R564L and JAK2 I670V point mutation variants to be associated with a myelodysplastic phenotype.

CONCLUSIONS

JAK2 mutations in MDS are rare and represent less than 3% of cases. It appears that JAK2 variant mutations in MDS are diverse and further studies are needed to understand their role in the phenotype and prognosis of the disease.

TP53-altered acute myeloid leukemia and myelodysplastic syndrome with excess blasts should be approached as a single entity

TP53-altered myelodysplastic syndrome with excess blasts and TP53-altered acute myeloid leukemia should be considered under one unifying classification term for their study in clinical trials. Ultimately, such a unification would simplify the screening processes for clinical trials and allow a focus on treating the patient for a genetically defined disorder rather than one based on an arbitrary blast threshold.

Drugs Targeting p53 Mutations with FDA Approval and in Clinical Trials

Mutations in the tumor suppressor p53 (p53) promote cancer progression. This is mainly due to loss of function (LOS) as a tumor suppressor, dominant-negative (DN) activities of missense mutant p53 (mutp53) over wild-type p53 (wtp53), and wtp53-independent oncogenic activities of missense mutp53 by interacting with other tumor suppressors or oncogenes (gain of function: GOF). Since p53 mutations occur in ~50% of human cancers and rarely occur in normal tissues, p53 mutations are cancer-specific and ideal therapeutic targets. Approaches to target p53 mutations include (1) restoration or stabilization of wtp53 conformation from missense mutp53, (2) rescue of p53 nonsense mutations, (3) depletion or degradation of mutp53 proteins, and (4) induction of p53 synthetic lethality or targeting of vulnerabilities imposed by p53 mutations (enhanced YAP/TAZ activities) or deletions (hyperactivated retrotransposons). This review article focuses on clinically available FDA-approved drugs and drugs in clinical trials that target p53 mutations and summarizes their mechanisms of action and activities to suppress cancer progression.

How I treat with maintenance therapy after allogeneic HCT

Disease relapse is the leading cause of failure for patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Maintenance therapy administered after allo-HCT is a promising strategy to reduce the incidence of relapse and enhance the curative potential of allo-HCT. Research investigations and clinical applications of this approach have greatly increased in recent years, with an expanding number of available therapeutic agents to introduce in the posttransplant setting. However, many questions and challenges remain regarding the feasibility and clinical impact of maintenance. In this article, we present four common case scenarios addressing select available therapeutic agents as a framework to review published data and ongoing studies and describe our current standard practice in the rapidly evolving field of maintenance therapy after allo-HCT.

Current status of phase 3 clinical trials in high-risk myelodysplastic syndromes: pitfalls and recommendations

Single-agent hypomethylating agents remain the cornerstone of treatment for patients with high-risk myelodysplastic syndromes. Although these agents have clinical activity and can improve the overall survival of these patients, their impact on the natural history of myelodysplastic syndromes is only partial. Therefore, we need either newer agents or combinations that could have a greater impact on the survival of our patients. Over the past decade there has been an increased effort in drug development for myelodysplastic syndromes. Hypomethylating agent combinations that have been explored over the past decade include agents that block mutant TP53, NEDD inhibitors, BCL-2 inhibitors, and antibodies such as sabatolimab or magrolimab. Despite initial encouraging results, two registration trials from 2021 and 2022 have not been successful in improving outcomes when compared with single-agent hypomethylating agents. Here, I summarise the current status of ongoing phase 3 trials for patients with untreated high-risk myelodysplastic syndromes and provide some suggestions for future designs.

Appropriate pre-transplant strategy for patients with myelodysplastic syndromes receiving allogeneic haematopoietic stem cell transplantation after myeloablative conditioning

Purpose

Appropriate pre-transplant strategies in patients with myelodysplastic syndromes (MDS) remain challenging. We sought to assess the effect of different pre-transplant therapies and transplantation interval times on patient prognosis.

Methods

We retrospectively analysed clinical data for 371 consecutive MDS patients after myeloablative transplantation between 2007 and 2019.

Results

The median age of the patients was 38 years (range, 12-64 years). A total of 114 patients (31%) received supportive care (SC), 108 (29%) hypomethylating agents (HMAs), and 149 (40%) chemotherapy-based therapy before transplantation. In patients who received HMA or SC, there was no significant difference in overall survival (OS; P=0.151) or relapse-free survival (RFS; P=0.330), except that HMA-treated patients had a lower rate of non-relapse mortality (5-year NRM: 18% vs. 32%, P=0.035). However, compared with patients who received HMA, those who received chemotherapy-based therapy had a lower 5-year OS rate (56% vs. 69%, P=0.020) and a slightly higher 5-year NRM rate (28% vs. 18%, P=0.067). Compared to the delayed transplant group (transplant interval ≥6 months), the early transplant group (transplant interval <6 months) had a superior 5-year OS (66% vs. 51%, P=0.001) and a lower 5-year cumulative incidence of NRM (22% vs. 36%, P=0.001).

Conclusion

The findings of the study indicate that receiving an appropriate pre-transplant strategy (SC/HMA + <6 months) significantly improves OS and decreases NRM in MDS patients after myeloablative transplantation.

Erythropoiesis in lower-risk myelodysplastic syndromes and beta-thalassemia

The hematologic disorders myelodysplastic syndromes and beta-thalassemia are characterized by ineffective erythropoiesis and anemia, often managed with regular blood transfusions. Erythropoiesis, the process by which sufficient numbers of functional erythrocytes are produced from hematopoietic stem cells, is highly regulated, and defects can negatively affect the proliferation, differentiation, and survival of erythroid precursors. Treatments that directly target the underlying mechanisms of ineffective erythropoiesis are limited, and management of anemia with regular blood transfusions imposes a significant burden on patients, caregivers, and health care systems. There is therefore a strong unmet need for treatments that can restore effective erythropoiesis. Novel therapies are beginning to address this need by targeting a variety of mechanisms underlying erythropoiesis. Herein, we provide an overview of the role of ineffective erythropoiesis in myelodysplastic syndromes and beta-thalassemia, discuss unmet needs in targeting ineffective erythropoiesis, and describe current management strategies and emerging treatments for these disorders.