Dynamic acquisition of FLT3 or RAS alterations drive a subset of patients with lower risk MDS to secondary AML

Next generation sequencing reveals the mutation landscape of Chinese MDS patients and the association between mutations and AML transformations

BACKGROUND/OBJECTIVE

Approximately 30% of patients with MDS eventually develop to acute myeloid leukemia (AML). Our study aimed to investigate the mutation landscape of Chinese MDS patients and identify the mutated genes which are closely implicated in the transformation of MDS to AML.

METHODS

In total, 412 sequencing data collected from 313 patients were used for analysis. Mutation frequencies between different groups were compared by Fisher's exact. A predictive model for risk of transformation/death of newly diagnosed patients was constructed by logistic regression.

RESULTS

The most frequently mutated genes in newly diagnosed patients were TP53, TET2, RUNX1, PIGA, and BCOR and mutations of RUNX1, TP53, BCORL1, TET2, and BCOR genes were more common in the treated MDS patients. Besides, we found that the mutation frequencies of IDH2, TET2, and EZH2 were significantly higher in MDS patients aged over 60 years. Moreover, two mutation sites, KRASG12A and TP53H140N were detected only at transformation in one patient, while not detected at diagnosis. In addition, the mutation frequencies of EZH2 V704F and TET2 I1873N were stable from diagnosis to transformation in two patients. Finally, we constructed a predictive model for risk of transformation/death of newly diagnosed patients combing detected data of 10 genes and the number of to leukocyte, with a sensitivity of 63.3% and a specificity of 84.6% in distinguishing individuals with and without risk of transformation/death.

CONCLUSION

In summary, our study found several mutations associated with the transformation from MDS to AML, and constructed a predictive model for risk of transformation/death of MDS patients.

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.

Novel insights and therapeutic approaches in secondary AML

Secondary acute myeloid leukemia (sAML) presents as a complex and multifaceted ensemble of disorders, positioning itself as both a challenge and an intriguing frontier within hematologic oncology. Its origins are diverse, stemming from antecedent hematologic conditions, germline predisposing mutations, or the sequelae of cytotoxic therapies, and its development is driven by intricate genetic and epigenetic modifications. This complexity necessitates a diverse array of therapeutic strategies, each meticulously tailored to address the distinctive challenges sAML introduces. Such strategies require a personalized approach, considering the variegated clinical backgrounds of patients and the inherent intricacies of the disease. Allogeneic stem cell transplantation stands as a cornerstone, offering the potential for curative outcomes. This is complemented by the emergence of innovative treatments such as CPX-351, venetoclax, and glasdegib, which have demonstrated promising results in enhancing prognosis. The evolving landscape of sAML treatment underscores the importance of continued research and innovation in the field, aiming not only to improve patient outcomes but also to deepen our understanding of the disease's biological underpinnings, thereby illuminating pathways toward more effective and individualized therapies.

Phase 1 study of azacitidine in combination with quizartinib in patients with FLT3 or CBL mutated MDS and MDS/MPN

We conducted a phase 1 study evaluating 3 dose levels of quizartinib (30 mg, 40 mg or 60 mg) in combination with azacitidine for HMA-naïve or relapsed/refractory MDS or MDS/MPN with FLT3 or CBL mutations. Overall, 12 patients (HMA naïve: n=9, HMA failure: n=3) were enrolled; 7 (58 %) patients had FLT3 mutations and 5 (42 %) had CBL mutations. The maximum tolerated dose was not reached. Most common grade 3-4 treatment-emergent adverse events were thrombocytopenia (n=5, 42 %), anemia (n=4, 33 %), lung infection (n=2, 17 %), skin infection (n=2, 17 %), hyponatremia (n=2, 17 %) and sepsis (n=2, 17 %). The overall response rate was 83 % with median relapse-free and overall survivals of 15.1 months (95 % CI 0.0-38.4 months) and 17.5 months (95 % CI NC-NC), respectively. FLT3 mutation clearance was observed in 57 % (n=4) patients. These data suggest quizartinib is safe and shows encouraging activity in FLT3-mutated MDS and MDS/MPN. This study is registered at Clinicaltrials.gov as NCT04493138.

Updates in biology, classification, and management of acute myeloid leukemia with antecedent hematologic disorder and therapy related acute myeloid leukemia

Acute myeloid leukemia with antecedent hematologic disorder (AHD-AML) and therapy related AML (t-AML) constitute a heterogenous disease with inferior outcomes. It is often characterized by high-risk cytogenetic and molecular alterations associated with AHD or prior cancer therapy. Historically, the standard of care treatment has been intensive induction with "7 + 3", with an improved overall response rate and survival with CPX-351. Results from large registry-based studies suggested that allogeneic hematopoietic stem cell transplant is preferable to consolidation chemotherapy alone for achieving long-term survival in patients with AHD-AML. Prevalence of high-risk genetic features and advanced age and comorbidities in patients make AHD-AML and t-AML clinically challenging subgroups to treat with intensive approaches. Recent reports on less intensive treatment options, particularly the hypomethylating agent-venetoclax combination, have shown encouraging response rates in these patients. However, emerging resistance mechanisms compromise duration of response and overall survival. Several novel agents targeting apoptotic machinery, signaling pathways, and immune checkpoints are under clinical investigation, with an aim to truly improve overall outcomes in this subgroup. We reviewed updates in biology, classification, and clinical data comparing safety and efficacy of intensive and less intensive treatment options, and summarized ongoing studies with promising novel therapies in AHD-AML and t-AML.

The potential of triplet combination therapies for patients with FLT3-ITD -mutated acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) encompasses a heterogeneous group of aggressive myeloid malignancies, where FMS-like tyrosine kinase 3 (FLT3) mutations are prevalent, accounting for approximately 25-30% of adult patients. The presence of this mutation is related to a dismal prognosis and high relapse rates. In the lasts years many FLT3 inhibitors have been developed.

AREAS COVERED

This review provides a comprehensive overview of FLT3mut AML, summarizing the state of art of current treatment and available data about combination strategies including an FLT3 inhibitor.

EXPERT OPINION

In addition, the review discusses the emergence of drug resistance and the need for a nuanced approaches in treating patients who are ineligible for or resistant to intensive chemotherapy. Specifically, it explores the historical context of FLT3 inhibitors (FLT3Is) and their impact on treatment outcomes, emphasizing the pivotal role of midostaurin, as well as gilteritinib and quizartinib, and providing detailed insights into ongoing trials exploring the safety and efficacy of novel triplet combinations involving FLT3Is in different AML settings.

Malignant progression of preleukemic disorders

ABSTRACT

The spectrum of myeloid disorders ranges from aplastic bone marrow failure characterized by an empty bone marrow completely lacking in hematopoiesis to acute myeloid leukemia in which the marrow space is replaced by undifferentiated leukemic blasts. Recent advances in the capacity to sequence bulk tumor population as well as at a single-cell level has provided significant insight into the stepwise process of transformation to acute myeloid leukemia. Using models of progression in the context of germ line predisposition (trisomy 21, GATA2 deficiency, and SAMD9/9L syndrome), premalignant states (clonal hematopoiesis and clonal cytopenia of unknown significance), and myelodysplastic syndrome, we review the mechanisms of progression focusing on the hierarchy of clonal mutation and potential roles of transcription factor alterations, splicing factor mutations, and the bone marrow environment in progression to acute myeloid leukemia. Despite major advances in our understanding, preventing the progression of these disorders or treating them at the acute leukemia phase remains a major area of unmet medical need.

Acute myeloid leukaemia

Progress in acute myeloid leukaemia treatment is occurring at an unprecedented pace. The past decade has witnessed an increasingly improved scientific understanding of the underlying biology of acute myeloid leukaemia, leading to enhanced prognostication tools and refined risk assessments, and most especially incorporating measurable residual disease (MRD) into longitudinal risk assessments. The classification of acute myeloid leukaemia has recently been updated by WHO and the International Consensus Classification (ICC). Recommendations for prognostic stratification, response assessment, and MRD determination have also been updated by the European LeukemiaNet. Treatment options have evolved substantially in the last 5 years for patients with newly diagnosed acute myeloid leukaemia, leading to improved outcomes in intensively treated patients and those more appropriate for non-intensive chemotherapy. More effective targeted treatment options in the relapsed setting are also available, further advancing the treatment armamentarium and improving patient outcomes.

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.

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.

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.

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.

Navigating the contested borders between myelodysplastic syndrome and acute myeloid leukemia

Myelodysplastic syndrome and acute myeloid leukemia are heterogeneous myeloid neoplasms which arise from the accumulation of mutations in a myeloid stem cell or progenitor that confer survival or growth advantages. These disease processes are formally differentiated by clinical, laboratory, and morphological presentations, especially with regard to the preponderance of blasts in the peripheral blood or bone marrow (AML); however, they are closely associated through their shared lineage as well as their existence on a spectrum with some cases of MDS displaying increased blasts, a feature that reflects more AML-like behavior, and the propensity for MDS to transform into AML. It is increasingly recognized that the distinctions between these two entities result from the divergent patterns of genetic alterations that drive each of them. Mutations in genes related to chromatin-remodeling and the spliceosome are seen in both MDS and AML arising out of antecedent MDS, while mutations in genes related to signaling pathways such as RAS or FLT3 are more typically seen in AML or otherwise are a harbinger of transformation. In this review, we focus on the insights into the biological and genetic distinctions and similarities between MDS and AML that are now used to refine clinical prognostication, guide disease management, and to inform development of novel therapeutic approaches.

Molecular Diagnostic Testing for Hematopoietic Neoplasms: Linking Pathogenic Drivers to Personalized Diagnosis

Molecular diagnostics inhabit an increasingly central role in characterizing hematopoietic malignancies. This brief review summarizes the genomic targets important for many major categories of hematopoietic neoplasia by focusing on disease pathogenesis. In myeloid disease, recurrent mutations in key functional classes drive clonal hematopoiesis, on which additional variants can specify clinical presentation and accelerate progression. Lymphoblastic leukemias are frequently initiated by oncogenic fusions that block lymphoid maturation while, in concert with additional mutations, driving proliferation. The links between genetic aberrations and lymphoma patient outcomes have been clarified substantially through the clustering of genomic profiles. Finally, the addition of next-generation sequencing strategies to cytogenetics is refining risk stratification for plasma cell myeloma. In all categories, molecular diagnostics shed light on the unique mechanistic underpinnings of each individual malignancy, thereby empowering more rational, personalized care for these patients.

Convergent Clonal Evolution of Signaling Gene Mutations Is a Hallmark of Myelodysplastic Syndrome Progression

Progression from myelodysplastic syndromes (MDS) to secondary acute myeloid leukemia (AML) is associated with the acquisition and expansion of subclones. Our understanding of subclone evolution during progression, including the frequency and preferred order of gene mutation acquisition, remains incomplete. Sequencing of 43 paired MDS and secondary AML samples identified at least one signaling gene mutation in 44% of MDS and 60% of secondary AML samples, often below the level of standard sequencing detection. In addition, 19% of MDS and 47% of secondary AML patients harbored more than one signaling gene mutation, almost always in separate, coexisting subclones. Signaling gene mutations demonstrated diverse patterns of clonal evolution during disease progression, including acquisition, expansion, persistence, and loss of mutations, with multiple patterns often coexisting in the same patient. Multivariate analysis revealed that MDS patients who had a signaling gene mutation had a higher risk of AML progression, potentially providing a biomarker for progression.

SIGNIFICANCE

Subclone expansion is a hallmark of progression from MDS to secondary AML. Subclonal signaling gene mutations are common at MDS (often at low levels), show complex and convergent patterns of clonal evolution, and are associated with future progression to secondary AML. See related article by Guess et al., p. 316 (33). See related commentary by Romine and van Galen, p. 270. This article is highlighted in the In This Issue feature, p. 265.

Distinct Mutation Landscapes Between Acute Myeloid Leukemia With Myelodysplasia-Related Changes and De Novo Acute Myeloid Leukemia

OBJECTIVES

To explore the distinct mutation profiles between acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) and de novo AML and their relationships with prognosis.

METHODS

Next-generation sequencing of 42 myeloid neoplasm-related genes in 293 newly diagnosed patients with AML.

RESULTS

Eighty-four patients had AML-MRC, and 161 patients had de novo AML. The mutation rates of ASXL1 (25% vs 8.7%, P = .001), NRAS (17.9% vs 8.1%, P = .022), PTPN11 (11.9% vs 5%, P = .048), SETBP1 (6% vs 0.6%, P = .033), SRSF2 (11.9% vs 5.6%, P = .08), TP53 (16.7% vs 1.2%, P < .001), and U2AF1 (17.9% vs 7.5%, P = .014) in AML-MRC were higher than those in de novo AML, while the rates of FLT3-ITD (3.6% vs 15.5%, P = .005), KIT (0% vs 6.2%, P = .046), WT1 (3.6% vs 9.9%, P = .077), NPM1 (1.2% vs 21.7%, P < .001), and CEBPA (4.8% vs 24.2%, P < .001) mutation were lower. The appearance of ASXL1, TP53, U2AF1, SRSF2, and SETBP1 mutation could predict AML-MRC-like features in de novo AML, which was related to older age (60 vs 51 years, P = .001), low WBC counts (4.7 × 109/L vs 11.6 × 109/L, P = .001), and inferior outcomes (median overall survival, 15 months vs not reached, P = .003).

CONCLUSIONS

The presence of AML-MRC-related mutations can reveal a subset of patients with de novo AML similar to patients with AML-MRC.

A review of FLT3 inhibitors in acute myeloid leukemia

FLT3 mutations are the most common genetic aberrations found in acute myeloid leukemia (AML) and associated with poor prognosis. Since the discovery of FLT3 mutations and their prognostic implications, multiple FLT3-targeted molecules have been evaluated. Midostaurin is approved in the U.S. and Europe for newly diagnosed FLT3 mutated AML in combination with standard induction and consolidation chemotherapy based on data from the RATIFY study. Gilteritinib is approved for relapsed or refractory FLT3 mutated AML as monotherapy based on the ADMIRAL study. Although significant progress has been made in the treatment of AML with FLT3-targeting, many challenges remain. Several drug resistance mechanisms have been identified, including clonal selection, stromal protection, FLT3-associated mutations, and off-target mutations. The benefit of FLT3 inhibitor maintenance therapy, either post-chemotherapy or post-transplant, remains controversial, although several studies are ongoing.

Case Report: Molecular Characterization of Aggressive Malignant Retroperitoneal Solitary Fibrous Tumor: A Case Study

Solitary fibrous tumors (SFT) are mesenchymal neoplasms with a favorable prognosis usually originating from the visceral pleura. Rarely, they may occur at various extrapleural sites and show malignant behavior coupled with dedifferentiation. NAB2-STAT6 fusion gene and STAT6 nuclear expression are biomarkers for diagnosis of SFT in addition to CD34, Bcl-2, and CD99. Furthermore, several reports have shown specific NAB2-STAT6 fusion variants and loss of STAT6 protein expression are associated with malignancy. We report a rare case of retroperitoneal SFT which rapidly progressed to death within 35 days after admission. Autopsy found a primary tumor containing both benign and malignant histologies, with multiple metastatic sites similar to the malignant, dedifferentiated tumor. STAT6 was detected in the primary differentiated tumor but not in the primary dedifferentiated tumor or lung/liver metastases. However, the NAB2-STAT6 fusion gene (NAB2ex6/STAT6ex16 variant) was detected in the primary tumor and lung/liver metastases. Intriguingly, fusion gene expression at the transcriptional level was downregulated in the dedifferentiated tumors compared to the differentiated tumor. We further performed target DNA sequencing and found gene mutations in TP53, FLT3, and AR in the dedifferentiated tumors, with TP53 mutations especially found among them. We demonstrate that downregulation of NAB2-STAT6 fusion gene at the transcriptional level is associated with malignant SFT for the first time. Moreover, the present study supports the idea that TP53 mutations promote malignancy in SFTs.

Myelodysplastic syndromes: Biological and therapeutic consequences of the evolving molecular aberrations landscape

Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders with heterogeneous presentation, ranging from indolent disease courses to aggressive diseases similar to acute myeloid leukemia (AML). Approximately 90% of MDS patients harbor recurrent mutations , which – with the exception of mutated SF3B1 –have not (yet) been included into the diagnostic criteria or risk stratification for MDS. Accumulating evidence suggests their utility for diagnostic workup, treatment indication and prognosis. Subsequently, in patients with unexplained cytopenia or dysplasia identification of these mutations may lead to earlier diagnosis. The acquisition and expansion of additional driver mutations usually antecedes further disease progression to higher risk MDS or secondary AML and thus, can be clinically helpful to detect individuals that may benefit from aggressive treatment approaches. Here, we review our current understanding of somatic gene mutations, gene expression patterns and flow cytometry regarding their relevance for disease evolution from pre-neoplastic states to MDS and potentially AML.

Co-occurrence of cohesin complex and Ras signaling mutations during progression from myelodysplastic syndromes to secondary acute myeloid leukemia

Myelodysplastic syndromes (MDS) are hematological disorders at high risk of progression to secondary acute myeloid leukemia (sAML). However, the mutational dynamics and clonal evolution underlying disease progression are poorly understood at present. To elucidate the mutational dynamics of pathways and genes occurring during the evolution to sAML, next generation sequencing was performed on 84 serially paired samples of MDS patients who developed sAML (discovery cohort) and 14 paired samples from MDS patients who did not progress to sAML during follow-up (control cohort). Results were validated in an independent series of 388 MDS patients (validation cohort). We used an integrative analysis to identify how mutations, alone or in combination, contribute to leukemic transformation. The study showed that MDS progression to sAML is characterized by greater genomic instability and the presence of several types of mutational dynamics, highlighting increasing (STAG2) and newly-acquired (NRAS and FLT3) mutations. Moreover, we observed cooperation between genes involved in the cohesin and Ras pathways in 15-20% of MDS patients who evolved to sAML, as well as a high proportion of newly acquired or increasing mutations in the chromatin-modifier genes in MDS patients receiving a disease-modifying therapy before their progression to sAML.

Navigating Myelodysplastic and Myelodysplastic/Myeloproliferative Overlap Syndromes

Myelodysplastic syndromes (MDS) and MDS/myeloproliferative neoplasms (MPNs) are clonal diseases that differ in morphologic diagnostic criteria but share some common disease phenotypes that include cytopenias, propensity to acute myeloid leukemia evolution, and a substantially shortened patient survival. MDS/MPNs share many clinical and molecular features with MDS, including frequent mutations involving epigenetic modifier and/or spliceosome genes. Although the current 2016 World Health Organization classification incorporates some genetic features in its diagnostic criteria for MDS and MDS/MPNs, recent accumulation of data has underscored the importance of the mutation profiles on both disease classification and prognosis. Machine-learning algorithms have identified distinct molecular genetic signatures that help refine prognosis and notable associations of these genetic signatures with morphologic and clinical features. Combined geno-clinical models that incorporate mutation data seem to surpass the current prognostic schemes. Future MDS classification and prognostication schema will be based on the portfolio of genetic aberrations and traditional features, such as blast count and clinical factors. Arriving at these systems will require studies on large patient cohorts that incorporate advanced computational analysis. The current treatment algorithm in MDS is based on patient risk as derived from existing prognostic and disease classes. Luspatercept is newly approved for patients with MDS and ring sideroblasts who are transfusion dependent after erythropoietic-stimulating agent failure. Other agents that address red blood cell transfusion dependence in patients with lower-risk MDS and the failure of hypomethylating agents in higher-risk disease are in advanced testing. Finally, a plethora of novel targeted agents and immune checkpoint inhibitors are being evaluated in combination with a hypomethylating agent backbone to augment the depth and duration of response and, we hope, improve overall survival.

Myelodysplastic syndromes: 2021 update on diagnosis, risk stratification and management

DISEASE OVERVIEW

The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increased risk of transformation to acute myelogenous leukemia (AML). Myelodysplastic syndromes occur more frequently in older males and in individuals with prior exposure to cytotoxic therapy.

DIAGNOSIS

Diagnosis of MDS is based on morphological evidence of dysplasia upon visual examination of a bone marrow aspirate and biopsy. Information obtained from additional studies such as karyotype, flow cytometry and molecular genetics is usually complementary and may help refine diagnosis.

RISK-STRATIFICATION

Prognosis of patients with MDS can be calculated using a number of scoring systems. In general, all these scoring systems include analysis of peripheral cytopenias, percentage of blasts in the bone marrow and cytogenetic characteristics. The most commonly accepted system is the Revised International Prognostic Scoring System (IPSS-R). Somatic mutations can help define prognosis and therapy.

RISK-ADAPTED THERAPY

Therapy is selected based on risk, transfusion needs, percent of bone marrow blasts, cytogenetic and mutational profiles, comorbidities, potential for allogeneic stem cell transplantation (alloSCT) and prior exposure to hypomethylating agents (HMA). Goals of therapy are different in lower-risk patients than in higher-risk individuals and in those with HMA failure. In lower-risk MDS, the goal is to decrease transfusion needs and transformation to higher risk disease or AML, as well as to improve survival. In higher-risk disease, the goal is to prolong survival. In 2020, we witnessed an explosion of new agents and investigational approaches. Current available therapies include growth factor support, lenalidomide, HMAs, intensive chemotherapy and alloSCT. Novel therapeutics approved in 2020 are luspatercept and the oral HMA ASTX727. At the present time, there are no approved interventions for patients with progressive or refractory disease particularly after HMA-based therapy. Options include participation in a clinical trial, cytarabine-based therapy or alloSCT.

[Molecular features and prognostic value of RAS mutations in patients with myelodysplastic syndromes]

Objective: To explore the molecular features and prognostic value of RAS mutations in patients with myelodysplastic syndromes (MDS) . Methods: 112-gene targeted sequencing was conducted to detect RAS mutations in 776 patients with newly diagnosed primary MDS from December 2011 to December 2018. The mutual exclusivity and co-occurrence in gene mutations and clonal architecture were explored. Moreover, the prognostic significance of RAS mutations in MDS was analyzed. Results: RAS gene mutations were found in 52 (6.7% ) cases, 38 (4.9% ) of whom harbored NRAS mutation, 18 (2.3% ) KRAS mutation, and 4 (0.5% ) both NRAS and KRAS mutations. All the NRAS mutations and 65% of the KRAS mutations were located in codons 12, 13, and 61. PTPN11, FLT3, U2AF1, RUNX1, WT1, ETV6, and NPM1 mutations were enriched in patients with RAS mutations (Q<0.05) . Around 80% of RAS mutations represented subclonal lesions in patients who harbored at least two different mutations. Patients with RAS mutations were more frequently diagnosed with MDS with excess blast (MDS-EB) (82.7% vs. 35.2% , P<0.001) and had higher levels of white blood cell count (4.33×10(9)/L vs. 2.71×10(9)/L, P<0.001) , neutrophil absolute count (2.13×10(9)/L vs. 1.12×10(9)/L, P<0.001) , and bone marrow blast percentage (7% vs. 2% , P<0.001) but lower levels of platelet count (48×10(9)/L vs. 62×10(9)/L, P=0.048) . RAS mutations were correlated with higher-risk categories in the Revised International Prognostic Scoring System (IPSS-R) (71.1% vs. 37.9% , P<0.001) . The median overall survival of patients with NRAS mutations was shorter than the others (P=0.011) , while the significance was lost in the multivariable model. Conclusion: RAS gene mutations always occurred in the late-stage MDS and co-occurred with other signal transduction- and transcription factor-related gene mutations. PTPN11, a RAS pathway-related gene, is an independent poor prognostic factor in MDS patients.

Genetic and Genomic Landscape of Secondary and Therapy-Related Acute Myeloid Leukemia

A subset of acute myeloid leukemia (AML) arises either from an antecedent myeloid malignancy (secondary AML, sAML) or as a complication of DNA-damaging therapy for other cancers (therapy-related myeloid neoplasm, t-MN). These secondary leukemias have unique biological and clinical features that distinguish them from de novo AML. Over the last decade, molecular techniques have unraveled the complex subclonal architecture of sAML and t-MN. In this review, we compare and contrast biological and clinical features of de novo AML with sAML and t-MN. We discuss the role of genetic mutations, including those involved in RNA splicing, epigenetic modification, tumor suppression, transcription regulation, and cell signaling, in the pathogenesis of secondary leukemia. We also discuss clonal hematopoiesis in otherwise healthy individuals, as well as in the context of another malignancy, and how it challenges the conventional notion of sAML/t-MN. We conclude by summarizing the current and emerging treatment strategies, including allogenic transplant, in these complex scenarios.

Genetics of progression from MDS to secondary leukemia

Our understanding of the genetics of acute myeloid leukemia (AML) development from myelodysplastic syndrome (MDS) has advanced significantly as a result of next-generation sequencing technology. Although differences in cell biology and maturation exist between MDS and AML secondary to MDS, these 2 diseases are genetically related. MDS and secondary AML cells harbor mutations in many of the same genes and functional categories, including chromatin modification, DNA methylation, RNA splicing, cohesin complex, transcription factors, cell signaling, and DNA damage, confirming that they are a disease continuum. Differences in the frequency of mutated genes in MDS and secondary AML indicate that the order of mutation acquisition is not random during progression. In almost every case, disease progression is associated with clonal evolution, typically defined by the expansion or emergence of a subclone with a unique set of mutations. Monitoring tumor burden and clonal evolution using sequencing provides advantages over using the blast count, which underestimates tumor burden, and could allow for early detection of disease progression prior to clinical deterioration. In this review, we outline advances in the study of MDS to secondary AML progression, with a focus on the genetics of progression, and discuss the advantages of incorporating molecular genetic data in the diagnosis, classification, and monitoring of MDS to secondary AML progression. Because sequencing is becoming routine in the clinic, ongoing research is needed to define the optimal assay to use in different clinical situations and how the data can be used to improve outcomes for patients with MDS and secondary AML.

Myelodysplastic Syndromes: How to Recognize Risk and Avoid Acute Myeloid Leukemia Transformation

PURPOSE OF REVIEW

To understand how myelodysplastic syndromes (MDS) transform to AML and to describe how transformation can be predicted and prevented.

RECENT FINDINGS

Recent genomic analyses have shown that MDS progression to AML is associated with clonal expansion and clonal evolution. Mutation profiles of MDS change during progression and new mutations in signaling genes and transcription factors emerge. AML transformation can be predicted by several parameters including International Prognostic Scoring System IPSS risk category and transfusion requirements. The prognostic relevance of the acquisition of some gene mutations (i.e., IDH1 and 2, CBL, FT3, RAS, NPM1, TP53, and ASXL1) has to be prospectively validated. The most effective preventive therapy for AML transformation is allogeneic stem cell transplantation. Hypomethylating agents have been associated with prolonged time to AML transformation even in patients who did not achieve an objective response. The recent progress in the understanding of the molecular events leading to transformation and the event of new effective therapies open new avenues for a better prediction and prevention of AML transformation in patients with MDS.

Secondary Acute Myeloid Leukemia: A Primary Challenge of Diagnosis and Treatment

Secondary acute myeloid leukemia (sAML) is a complex diagnosis that includes AML caused by either an antecedent hematologic disease (AML-AHD) or from previous treatment with chemotherapy or radiation. This disease carries a poor prognosis and is historically chemorefractory; additionally, often patients are ineligible for standard chemotherapy because of advanced age and other comorbidities. The advances of molecular diagnostics and reclassification of World Health Organization criteria have aided in the categorization of this disease. This article describes the etiology and pathophysiology of sAML, and delves into past successful treatments as well as promising new treatments.

TP53 mutation status divides myelodysplastic syndromes with complex karyotypes into distinct prognostic subgroups

Risk stratification is critical in the care of patients with myelodysplastic syndromes (MDS). Approximately 10% have a complex karyotype (CK), defined as more than two cytogenetic abnormalities, which is a highly adverse prognostic marker. However, CK-MDS can carry a wide range of chromosomal abnormalities and somatic mutations. To refine risk stratification of CK-MDS patients, we examined data from 359 CK-MDS patients shared by the International Working Group for MDS. Mutations were underrepresented with the exception of TP53 mutations, identified in 55% of patients. TP53 mutated patients had even fewer co-mutated genes but were enriched for the del(5q) chromosomal abnormality (p < 0.005), monosomal karyotype (p < 0.001), and high complexity, defined as more than 4 cytogenetic abnormalities (p < 0.001). Monosomal karyotype, high complexity, and TP53 mutation were individually associated with shorter overall survival, but monosomal status was not significant in a multivariable model. Multivariable survival modeling identified severe anemia (hemoglobin < 8.0 g/dL), NRAS mutation, SF3B1 mutation, TP53 mutation, elevated blast percentage (>10%), abnormal 3q, abnormal 9, and monosomy 7 as having the greatest survival risk. The poor risk associated with CK-MDS is driven by its association with prognostically adverse TP53 mutations and can be refined by considering clinical and karyotype features.

Genomic loss of HLA alleles may affect the clinical outcome in low-risk myelodysplastic syndrome patients

The Revised International Prognostic Score and some somatic mutations in myelodysplastic syndrome (MDS) are independently associated with transformation to acute myeloid leukemia (AML). Immunity has also been implicated in the pathogenesis of MDS, although the underlying mechanism remains unclear. We performed a SNP array on chromosome 6 in CD34⁺ purified blasts from 19 patients diagnosed with advanced MDS and 8 patients with other myeloid malignancies to evaluate the presence of loss of heterozygosity (LOH) in HLA and its impact on disease progression. Three patients had acquired copy-neutral LOH (CN-LOH) on 6p arms, which may disrupt antigen presentation and act as a mechanism for immune system evasion. Interestingly, these patients had previously been classified at low risk of AML progression, and the poor outcome cannot be explained by the acquisition of adverse mutations. LOH HLA was not detected in the remaining 24 patients, who all had adverse risk factors. In summary, the clinical outcome of patients with advanced MDS might be influenced by HLA allelic loss, wich allows subclonal expansions to evade cytotoxic-T and NK cell attack. CN-LOH HLA may therefore be a factor favoring MDS progression to AML independently of the somatic tumor mutation load.

The Role of FLT3-ITD Mutation on de Novo MDS in Chinese Population

BACKGROUND

FLT3 mutations have been well-studied in acute myeloid leukemia (AML), and the detection of the FLT3 gene has become a clinical routine. However, it has not been fully analyzed in other hematologic malignancies, such as myelodysplastic syndromes (MDS).

MATERIALS AND METHODS

Between 2010 and 2016, 304 adult patients with de novo MDS had the FLT3 sequence tested on their bone marrow sample. With 279 patients who had follow-up information, we also analyzed the impact of clinical and laboratory characteristics as well as FLT3 mutation status and treatment on prognosis.

RESULTS

We found that the transformation rate was 3 (42.9%) of 7 patients in the FLT3-ITD-positive group, compared with 31 (10.4%) of 297 among FLT3-ITD-negative patients (P = .033). The median progression-free survival of the FLT3-ITD mutated and wild-type groups were 43 days and 363.5 days, respectively (P < .0001). The median overall survival (OS) of the 2 groups were 218 days and 410.5 days, respectively (P < .0001). We also found that 5 factors had independent prognostic impact on OS: white blood cell counts, bone marrow blast percentage, cytogenetics, transplantation status, and FLT3-ITD mutation. Furthermore, compared with the transformation group, the non-progression group was younger (P = .034), with a lower platelet count (P = .022), a lower bone marrow blast percentage (P = .001), a lower FLT3-ITD incidence (P = .007), and a longer OS (P < .0001).

CONCLUSIONS

When observed at the MDS stage, patients harboring FLT3-ITD mutations had higher AML transformation rate, quicker disease progression, and shorter survival than wild-type patients. Nevertheless, once the disease progressed to leukemia, the impact of FLT3-ITD mutations on prognosis was slight. In addition, the prognosis of secondary AML was very poor whether there was an FLT3-ITD mutation or not.

Acute Myeloid Leukemia: The Good, the Bad, and the Ugly

Acute myeloid leukemia (AML) was initially subdivided according to morphology (the French-American-British system), which proved helpful in pathologic categorization. Subsequently, clinical and genomic factors were found to correlate with response to chemotherapy and with overall survival. These included a history of antecedent hematologic disease, a history of chemotherapy or radiation therapy, the presence of various recurrent cytogenetic abnormalities, and, more recently, the presence of specific point mutations. This article reviews the biology and responses of one AML subgroup with consistent response and good outcomes following chemotherapy (core-binding factor leukemia), and two subgroups with persistently bad, and even ugly, outcomes (secondary AML and TP53-mutated AML).

Myelodysplastic syndromes: 2018 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increased risk of transformation to acute myelogenous leukemia (AML). MDS occurs more frequently in older males and in individuals with prior exposure to cytotoxic therapy.

DIAGNOSIS

Diagnosis of MDS is based on morphological evidence of dysplasia upon visual examination of a bone marrow aspirate and biopsy. Information obtained from additional studies such as karyotype, flow cytometry or molecular genetics is usually complementary and may help refine diagnosis.

RISK-STRATIFICATION

Prognosis of patients with MDS can be calculated using a number of scoring systems. In general, all these scoring systems include analysis of peripheral cytopenias, percentage of blasts in the bone marrow and cytogenetic characteristics. The most commonly used system is probably the International Prognostic Scoring System (IPSS). IPSS is now replaced by the revised IPSS-R score. Although not systematically incorporated into new validated prognostic systems, somatic mutations can help define prognosis and should be considered as new prognostic factors.

RISK-ADAPTED THERAPY

Therapy is selected based on risk, transfusion needs, percent of bone marrow blasts and cytogenetic and mutational profiles. Goals of therapy are different in lower risk patients than in higher risk. In lower risk, the goal is to decrease transfusion needs and transformation to higher risk disease or AML, as well as to improve survival. In higher risk, the goal is to prolong survival. Current available therapies include growth factor support, lenalidomide, hypomethylating agents, intensive chemotherapy and allogeneic stem cell transplantation. The use of lenalidomide has significant clinical activity in patients with lower risk disease, anemia and a chromosome 5 alteration. 5-azacitidine and decitabine have activity in both lower and higher-risk MDS. 5-azacitidine has been shown to improve survival in higher risk MDS. A number of new molecular lesions have been described in MDS that may serve as new therapeutic targets or aid in the selection of currently available agents. Additional supportive care measures may include the use of prophylactic antibiotics and iron chelation.

MANAGEMENT OF PROGRESSIVE OR REFRACTORY DISEASE

At the present time there are no approved interventions for patients with progressive or refractory disease particularly after hypomethylating based therapy. Options include participation in a clinical trial or cytarabine based therapy and stem cell transplantation.

[Gene mutations from 511 myelodysplastic syndromes patients performed by targeted gene sequencing]

Objective: To study the characteristics of gene mutations in Chinese myelodysplastic syndromes (MDS) patients. Methods: A total of 511 Chinese patients with MDS performed 112-gene targeted sequencing were retrospectively analyzed. Results: Eighty-three distinct mutant genes were found in 511 patients with MDS. Amongst these, the most frequent mutations was associated with epigenetics (50%) , followed by spliceosome (37%) , signal transduction (34%) , transcription factors (24%) and cell cycle/apoptosis (17%) . 439 subjects (86%) had at least one gene mutation. The mean number of mutations in refractory anemia with unilineage dysplasia (RCUD) was 1.25, refractory anemia with multilineage dysplasia (RCMD) was 1.73, refractory anemia with ring sideroblasts (RARS) was 2.79, refractory anemia with excess blasts-1 (RAEB-1) was 2.22, RAEB-2 was 2.34, MDS with isolated 5q- was 2.67, MDS, unclassified (MDS-U) was 2.00. U2AF1 mutant subjects were more likely to have isolated+8[Q<0.001, OR=4.42 (95% CI 2.23-8.68) ]and less likely to have complex karyotypes[Q=0.005, OR=0.22 (95% CI 0.04-0.72) ]. According to the number of gene mutations, all subjects were categorized into three groups, namely group with 0-1 mutation, with 2 mutations and with three or more mutations. There was a significant difference in overall survival (OS) among three groups (P=0.041) . Conclusion: About 90% patients with MDS have at least one gene mutation. Genes associated with epigenetics and spliceosome are most common mutated genes in MDS. The increased numbers of gene mutations accompany with disease evolution and associate with poor prognosis.

Treated secondary acute myeloid leukemia: a distinct high-risk subset of AML with adverse prognosis

Secondary acute myeloid leukemia (s-AML) includes therapy-related AML and AML evolving from antecedent hematological disorder (AHD). s-AML arising after treating AHD likely represents a prognostically distinct, high-risk disease category. In this study, treated s-AML (ts-AML) was defined by: (1) prior diagnosis of myelodysplasia, myeloproliferative neoplasm, or aplastic anemia and (2) at least 1 therapy for that diagnosis. ts-AML was categorized by age (< or ≥60 years), and each cohort assessed for response rates and overall survival (OS) on various treatment regimens. Survival outcomes were compared against other high-risk prognostic subsets. Results showed that complete response and 8-week mortality rates were 32% and 27% in the younger, and 24% and 19% in the older age groups, respectively. There was a significant OS difference within s-AML based on prior treatment of AHD (ie, ts-AML vs s-AML with untreated AHD, 4.2 vs 9.2 months; P < .001). Survival in ts-AML was poor across both cohorts (younger and older, 5 and 4.7 months, respectively). In younger AML, survival was significantly inferior in ts-AML when compared with deletion 5/7, TP53, 3q abnormality, and therapy-related AML groups (median, 5 vs 7.9, 7.8, 7.9, and 11.2 months, respectively; P < .01). Additional adverse karyotype within ts-AML was associated with even worse outcomes (OS range, 1.6-2.8 months). ts-AML represents a very high-risk category, even in younger AML patients. s-AML should be further classified to describe ts-AML, an entity less responsive to currently applied treatment approaches. Future AML trial designs should accommodate ts-AML as a distinct subgroup.

Molecular analysis of myelodysplastic syndrome with isolated deletion of the long arm of chromosome 5 reveals a specific spectrum of molecular mutations with prognostic impact: a study on 123 patients and 27 genes

The only cytogenetic aberration defining a myelodysplastic syndrome subtype is the deletion of the long arm of chromosome 5, which, along with morphological features, leads to the diagnosis of myelodysplastic syndrome with isolated deletion of the long arm of chromosome 5. These patients show a good prognosis and respond to treatment such as lenalidomide, but some cases progress to acute myeloid leukemia; however, the molecular mutation pattern is rarely characterized. Therefore, we investigated a large cohort of 123 myelodysplastic syndrome patients with isolated deletion of the long arm of chromosome 5, diagnosed following the World Health Organization classifications 2008 and 2016, by sequencing 27 genes. A great proportion of patients showed no or only one mutation. Only seven genes showed mutation frequencies >5% (SF3B1, DNMT3A, TP53, TET2, CSNK1A1, ASXL1, JAK2). However, the pattern of recurrently mutated genes was comparable to other myelodysplastic syndrome subtypes by comparison to a reference cohort, except that of TP53 which was significantly more often mutated in myelodysplastic syndrome with isolated deletion of the long arm of chromosome 5. As expected, SF3B1 was frequently mutated and correlated with ring sider-oblasts, while JAK2 mutations correlated with elevated platelet counts. Surprisingly, SF3B1 mutations led to significantly worse prognosis within cases with isolated deletion of the long arm of chromosome 5, but showed a comparable outcome to other myelodysplastic syndrome subtypes with SF3B1 mutation. However, addressing genetic stability in follow-up cases might suggest different genetic mechanisms for progression to secondary acute myeloid leukemia compared to overall myelodysplastic syndrome patients.

Clonal evolution in myelodysplastic syndromes

Cancer development is a dynamic process during which the successive accumulation of mutations results in cells with increasingly malignant characteristics. Here, we show the clonal evolution pattern in myelodysplastic syndrome (MDS) patients receiving supportive care, with or without lenalidomide (follow-up 2.5–11 years). Whole-exome and targeted deep sequencing at multiple time points during the disease course reveals that both linear and branched evolutionary patterns occur with and without disease-modifying treatment. The application of disease-modifying therapy may create an evolutionary bottleneck after which more complex MDS, but also unrelated clones of haematopoietic cells, may emerge. In addition, subclones that acquired an additional mutation associated with treatment resistance (TP53) or disease progression (NRAS, KRAS) may be detected months before clinical changes become apparent. Monitoring the genetic landscape during the disease may help to guide treatment decisions.

Myelodysplastic syndromes are a broad group of haematopoietic malignancies that often progress to acute myeloid leukaemia. Here, the authors show that linear and branched evolution occurs within myelodysplastic syndrome and these patterns can be impacted by treatment.

Clinical Implications of Genetic Mutations in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is clonal disorder characterized by ineffective hematopoiesis and a tendency to evolve into acute myeloid leukemia (AML). Genetic studies have enabled the identification of a set of recurrently mutated genes central to the pathogenesis of MDS, which can be organized into a limited number of cellular processes, including RNA splicing, epigenetic and traditional transcriptional regulation, and signal transduction. The sequential accumulation of mutations drives disease evolution from asymptomatic clonal hematopoiesis to frank MDS, and, ultimately, to secondary AML. This detailed understanding of the molecular landscape of MDS, coupled with the emergence of cost- and time-effective methodologies for DNA sequencing has led to the introduction of genetic studies into the clinical realm. Here, we review recent advances in our genetic understanding of MDS, with a particular focus on the emerging role for mutational data in clinical management as a potential tool to assist in diagnosis, risk stratification, and therapeutic decision-making.

The genetics of myelodysplastic syndrome: from clonal haematopoiesis to secondary leukaemia

Myelodysplastic syndrome (MDS) is a clonal disease that arises from the expansion of mutated haematopoietic stem cells. In a spectrum of myeloid disorders ranging from clonal haematopoiesis of indeterminate potential (CHIP) to secondary acute myeloid leukaemia (sAML), MDS is distinguished by the presence of peripheral blood cytopenias, dysplastic haematopoietic differentiation and the absence of features that define acute leukaemia. More than 50 recurrently mutated genes are involved in the pathogenesis of MDS, including genes that encode proteins involved in pre-mRNA splicing, epigenetic regulation and transcription. In this Review we discuss the molecular processes that lead to CHIP and further clonal evolution to MDS and sAML. We also highlight the ways in which these insights are shaping the clinical management of MDS, including classification schemata, prognostic scoring systems and therapeutic approaches.

Molecular and Cellular Mechanisms of Myelodysplastic Syndrome: Implications on Targeted Therapy

Myelodysplastic syndrome (MDS) is a group of heterogeneous clonal hematopoietic stem cell disorders characterized by cytopenia, ineffective hematopoiesis, and progression to secondary acute myeloid leukemia in high-risk cases. Conventional prognostication relies on clinicopathological parameters supplemented by cytogenetic information. However, recent studies have shown that genetic aberrations also have critical impacts on treatment outcome. Moreover, these genetic alterations may themselves be a target for treatment. The mutation landscape in MDS is shaped by gene aberrations involved in DNA methylation (TET2, DNMT3A, IDH1/2), histone modification (ASXL1, EZH2), the RNA splicing machinery (SF3B1, SRSF2, ZRSR2, U2AF1/2), transcription (RUNX1, TP53, BCOR, PHF6, NCOR, CEBPA, GATA2), tyrosine kinase receptor signaling (JAK2, MPL, FLT3, GNAS, KIT), RAS pathways (KRAS, NRAS, CBL, NF1, PTPN11), DNA repair (ATM, BRCC3, DLRE1C, FANCL), and cohesion complexes (STAG2, CTCF, SMC1A, RAD21). A detailed understanding of the pathogenetic mechanisms leading to transformation is critical for designing single-agent or combinatorial approaches in target therapy of MDS.

Detectable FLT3-ITD or RAS mutation at the time of transformation from MDS to AML predicts for very poor outcomes

BACKGROUND

The molecular events that drive the transformation from myelodysplastic syndromes (MDS) to acute myeloid leukemia (AML) have yet to be fully characterized. We hypothesized that detection of these mutations at the time of transformation from MDS to AML may lead to poorer outcomes.

METHODS

We analyzed 102 MDS patients who were admitted to our institution between 2004 and 2013, had wild-type (wt) FLT3-ITD and RAS at diagnosis, progressed to AML, and had serial mutation testing at both the MDS and AML stages.

RESULTS

We detected FLT3-ITD and/or RAS mutations in twenty-seven (26%) patients at the time of transformation to AML. Twenty-two patients (81%) had RAS mutations and five (19%) had FLT3-ITD mutations. The median survival after leukemia transformation in patients who had detectable RAS and/or FLT3-ITD mutations was 2.4 months compared to 7.5 months in patients who retained wt RAS and FLT3-ITD (hazard ratio [HR]: 3.08, 95% confidence interval [CI]: 1.9-5.0, p<0.0001). In multivariate analysis, FLT3-ITD and RAS mutations had independent prognostic significance for poor outcome.

Current state of prognostication and risk stratification in myelodysplastic syndromes

PURPOSE OF REVIEW

Myelodysplastic syndromes (MDS) are characterized by significant biologic and clinical heterogeneity. Because of the wide outcome variability, accurate prognostication is vital to high-quality risk-adaptive care of MDS patients. In this review, we discuss the current state of prognostic schemes for MDS and overview efforts aimed at utilizing molecular aberrations for prognostication in clinical practice.

RECENT FINDINGS

Several prognostic instruments have been developed and validated with increasing accuracy and complexity. Oncologists should be aware of the inherent limitations of these prognostic tools as they counsel patients and make clinical decisions. As more therapies are becoming available for MDS, the focus of model development is shifting from prognostic to treatment-specific predictive instruments. In addition to providing additional prognostic data beyond traditional clinical and pathologic parameters, the improved understanding of the genetic landscape and pathophysiologic consequences in MDS may allow the construction of treatment-specific predictive instruments.

SUMMARY

How to best use the results of molecular mutation testing to inform clinical decision making in MDS is still a work in progress. Important steps in this direction include standardization in performance and interpretation of assays and better understanding of the independent prognostic importance of the recurrent mutations, especially the less frequent ones.

Myelodysplastic syndromes: 2015 Update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increased risk of transformation to acute myelogenous leukemia (AML). MDS occurs more frequently in older males and in individuals with prior exposure to cytotoxic therapy.

DIAGNOSIS

Diagnosis of MDS is based on morphological evidence of dysplasia upon visual examination of a bone marrow aspirate and biopsy. Information obtained from additional studies such as karyotype, flow cytometry, or molecular genetics is complementary but not diagnostic. Risk-stratification: Prognosis of patients with MDS can be calculated using a number of scoring systems. In general, all these scoring systems include analysis of peripheral cytopenias, percentage of blasts in the bone marrow, and cytogenetic characteristics. The most commonly used system still is probably the International Prognostic Scoring System (IPSS). IPSS is being replaced by the new revised score IPSS-R.

RISK-ADAPTED THERAPY

Therapy is selected based on risk, transfusion needs, percent of bone marrow blasts, and more recently cytogenetic and mutational profiles. Goals of therapy are different in lower risk patients than in higher risk. In lower risk, the goal is to decrease transfusion needs and transformation to higher risk disease or AML, as well as to improve survival. In higher risk, the goal is to prolong survival. Current available therapies include growth factor support, lenalidomide, hypomethylating agents, intensive chemotherapy, and allogeneic stem cell transplantation. The use of lenalidomide has significant clinical activity in patients with lower risk disease, anemia, and a chromosome 5 alteration. 5-Azacitidine and decitabine have activity in higher risk MDS. 5-Azacitidine has been shown to improve survival in higher risk MDS. A number of new molecular lesions have been described in MDS that may serve as new therapeutic targets or aid in the selection of currently available agents. Additional supportive care measures may include the use of prophylactic antibiotics and iron chelation. Management of progressive or refractory disease: At the present time there are no approved interventions for patients with progressive or refractory disease particularly after hypomethylating based therapy. Options include participation in a clinical trial or cytarabine based therapy and stem cell transplantation.

Molecular mechanisms of the progression of myelodysplastic syndrome to secondary acute myeloid leukaemia and implication for therapy

Myelodysplastic syndrome (MDS) includes a heterogeneous group of clonal haematological stem cell disorders characterized by dysplasia, cytopenias, ineffective haematopoiesis, and an increased risk of progression to acute myeloid leukaemia (AML), which is also called secondary AML (sAML). Approximately one-third of patients with MDS will progress to sAML within a few months to a few years, and this type of transformation is more common and rapid in patients with high-risk MDS (HR-MDS). However, the precise mechanisms underlying the evolution of MDS to sAML remain unclear. Currently, chemotherapy for sAML has minimal efficacy. The only method of curing patients with sAML is allogeneic haematopoietic stem cell transplantation (Allo-HSCT). Unfortunately, only a few patients are appropriate for transplantation because this disease primarily affects older adult patients. Additionally, compared to de novo AML, sAML is more difficult to cure, and the prognosis is often worse. Therefore, it is important to clarify the molecular mechanisms of the progression of MDS to sAML and to explore the potent drugs for clinical use. This review will highlight several molecular mechanisms of the progression of MDS to sAML and new therapeutic strategies of this disease.

Clinical and genetic predictors of prognosis in myelodysplastic syndromes

Myelodysplastic syndromes are a collection of clonal hematopoietic disorders with a wide range of clinical manifestations and eventual outcomes. Accurate prediction of a patient's prognosis is useful to define the risk posed by the disease and which treatment options are most appropriate. Several models have been created to help predict the prognosis for patients with myelodysplastic syndromes. The International Prognostic Scoring System (IPSS) has been the standard tool used to risk stratify MDS patients since its publication in 1997. Other models have since been created to improve upon the IPSS, including the recent Revised International Prognostic Scoring System. Most models include the presence or severity of peripheral blood cytopenias, the proportion of bone marrow blasts, and specific karyotype abnormalities. Other factors including age, performance status, co-morbidities, transfusion dependence, and molecular biomarkers can further refine the prediction of prognosis in some models. Novel, disease specific biomarkers with prognostic value in myelodysplastic syndromes including cell surface markers, gene expression profiles, and high resolution copy number analyses have been proposed but not yet adopted clinically. Somatic abnormalities in recurrently mutated genes are the most informative prognostic biomarkers not currently considered by clinical risk models. Mutations in specific genes have independent prognostic significance and, unlike cytogenetic abnormalities, are present in the majority of myelodysplastic syndrome cases. However, mutational information can be complex and there are challenges to its clinical implementation. Despite these limitations, DNA sequencing can refine the prediction of prognosis for myelodysplastic syndrome patients and has become increasingly available in the clinic where it will help improve the care of patients with myelodysplastic syndromes.