In patients with acquired aplastic anemia, destruction of hematopoietic cells by the immune system leads to pancytopenia. Patients have a response to immunosuppressive therapy, but myelodysplastic ...syndromes and acute myeloid leukemia develop in about 15% of the patients, usually many months to years after the diagnosis of aplastic anemia.
We performed next-generation sequencing and array-based karyotyping using 668 blood samples obtained from 439 patients with aplastic anemia. We analyzed serial samples obtained from 82 patients.
Somatic mutations in myeloid cancer candidate genes were present in one third of the patients, in a limited number of genes and at low initial variant allele frequency. Clonal hematopoiesis was detected in 47% of the patients, most frequently as acquired mutations. The prevalence of the mutations increased with age, and mutations had an age-related signature. DNMT3A-mutated and ASXL1-mutated clones tended to increase in size over time; the size of BCOR- and BCORL1-mutated and PIGA-mutated clones decreased or remained stable. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and longer and a higher rate of overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes. However, clonal dynamics were highly variable and might not necessarily have predicted the response to therapy and long-term survival among individual patients.
Clonal hematopoiesis was prevalent in aplastic anemia. Some mutations were related to clinical outcomes. A highly biased set of mutations is evidence of Darwinian selection in the failed bone marrow environment. The pattern of somatic clones in individual patients over time was variable and frequently unpredictable. (Funded by Grant-in-Aid for Scientific Research and others.).
The splicing factor SF3B1 is the most commonly mutated gene in the myelodysplastic syndrome (MDS), particularly in patients with refractory anemia with ring sideroblasts (RARS). We investigated the ...functional effects of SF3B1 disruption in myeloid cell lines: SF3B1 knockdown resulted in growth inhibition, cell cycle arrest and impaired erythroid differentiation and deregulation of many genes and pathways, including cell cycle regulation and RNA processing. MDS is a disorder of the hematopoietic stem cell and we thus studied the transcriptome of CD34(+) cells from MDS patients with SF3B1 mutations using RNA sequencing. Genes significantly differentially expressed at the transcript and/or exon level in SF3B1 mutant compared with wild-type cases include genes that are involved in MDS pathogenesis (ASXL1 and CBL), iron homeostasis and mitochondrial metabolism (ALAS2, ABCB7 and SLC25A37) and RNA splicing/processing (PRPF8 and HNRNPD). Many genes regulated by a DNA damage-induced BRCA1-BCLAF1-SF3B1 protein complex showed differential expression/splicing in SF3B1 mutant cases. This is the first study to determine the target genes of SF3B1 mutation in MDS CD34(+) cells. Our data indicate that SF3B1 has a critical role in MDS by affecting the expression and splicing of genes involved in specific cellular processes/pathways, many of which are relevant to the known RARS pathophysiology, suggesting a causal link.
The 2016 revision of the World Health Organization classification of tumors of hematopoietic and lymphoid tissues is characterized by a closer integration of morphology and molecular genetics. ...Notwithstanding, the myelodysplastic syndrome (MDS) with isolated del(5q) remains so far the only MDS subtype defined by a genetic abnormality. Approximately half of MDS patients carry somatic mutations in spliceosome genes, with SF3B1 being the most commonly mutated one. SF3B1 mutation identifies a condition characterized by ring sideroblasts (RS), ineffective erythropoiesis, and indolent clinical course. A large body of evidence supports recognition of SF3B1-mutant MDS as a distinct nosologic entity. To further validate this notion, we interrogated the data set of the International Working Group for the Prognosis of MDS (IWG-PM). Based on the findings of our analyses, we propose the following diagnostic criteria for SF3B1-mutant MDS: (1) cytopenia as defined by standard hematologic values, (2) somatic SF3B1 mutation, (3) morphologic dysplasia (with or without RS), and (4) bone marrow blasts <5% and peripheral blood blasts <1%. Selected concomitant genetic lesions represent exclusion criteria for the proposed entity. In patients with clonal cytopenia of undetermined significance, SF3B1 mutation is almost invariably associated with subsequent development of overt MDS with RS, suggesting that this genetic lesion might provide presumptive evidence of MDS in the setting of persistent unexplained cytopenia. Diagnosis of SF3B1-mutant MDS has considerable clinical implications in terms of risk stratification and therapeutic decision making. In fact, this condition has a relatively good prognosis and may respond to luspatercept with abolishment of the transfusion requirement.
In humans, the majority of all protein-coding transcripts contain introns that are removed by mRNA splicing carried out by spliceosomes. Mutations in the spliceosome machinery have recently been ...identified using whole-exome/genome technologies in myelodysplastic syndromes (MDS) and in other hematological disorders. Alterations in splicing factor 3 subunit b1 (SF3b1) were the first spliceosomal mutations described, immediately followed by identification of other splicing factor mutations, including U2 small nuclear RNA auxillary factor 1 (U2AF1) and serine arginine-rich splicing factor 2 (SRSF2). SF3b1/U2AF1/SRSF2 mutations occur at varying frequencies in different disease subtypes, each contributing to differences in survival outcomes. However, the exact functional consequences of these spliceosomal mutations in the pathogenesis of MDS and other hematological malignancies remain largely unknown and subject to intense investigation. For SF3b1, a gain of function mutation may offer the promise of new targeted therapies for diseases that carry this molecular abnormality that can potentially lead to cure. This review aims to provide a comprehensive overview of the emerging role of the spliceosome machinery in the biology of MDS/hematological disorders with an emphasis on the functional consequences of mutations, their clinical significance, and perspectives on how they may influence our understanding and management of diseases affected by these mutations.
Paroxysmal nocturnal hemoglobinuria is a rare, acquired disease associated with hemolytic anemia, bone marrow failure, thrombosis, and, frequently, poor quality of life. The International PNH ...Registry is a worldwide, observational, non-interventional study collecting safety, effectiveness, and quality-of-life data from patients with a confirmed paroxysmal nocturnal hemoglobinuria diagnosis or detectable paroxysmal nocturnal hemoglobinuria clone, irrespective of treatment. In addition to evaluating the long-term safety and effectiveness of eculizumab in a global population, the registry aims to improve diagnosis, optimize patient management and outcomes, and enhance the understanding of the natural history of paroxysmal nocturnal hemoglobinuria. Here we report the characteristics of the first 1610 patients enrolled. Median disease duration was 4.6 years. Median granulocyte paroxysmal nocturnal hemoglobinuria clone size was 68.1% (range 0.01-100%). Overall, 16% of patients had a history of thrombotic events and 14% a history of impaired renal function. Therapies included anticoagulation (31%), immunosuppression (19%), and eculizumab (25%). Frequently reported symptoms included fatigue (80%), dyspnea (64%), hemoglobinuria (62%), abdominal pain (44%), and chest pain (33%). Patients suffered from poor quality of life; 23% of patients had been hospitalized due to paroxysmal nocturnal hemoglobinuria-related complications and 17% stated that paroxysmal nocturnal hemoglobinuria was the reason they were not working or were working less. This international registry will provide an ongoing, valuable resource to further the clinical understanding of paroxysmal nocturnal hemoglobinuria.
Although aplastic anemia and myelodysplasia have been extensively investigated, little is known about their circulating cytokine patterns. We compared plasma soluble cytokines in 33 aplastic anemia, ...57 myelodysplasia patients, and 48 healthy controls. High levels of thrombopoietin and granulocyte colony-stimulating factor, with low levels of CD40 ligand, chemokine (C-X-C motif) ligand 5, chemokine (C-C motif) ligand 5, chemokine (C-X-C motif) ligand 11, epidermal growth factor, vascular endothelial growth factor, and chemokine (C-C motif) ligand 11 were a signature profile for aplastic anemia. High levels of tumor necrosis factor-α, interleukin-6, chemokine (C-C motif) ligand 3, interleukin-1 receptor antagonist, and hepatocyte growth factor were a cytokine signature for myelodysplasia. Despite similar clinical presentations, distinct cytokine profiles were observed between aplastic anemia and hypocellular myelodysplasia. Future studies focusing on cytokines that better discriminate these two entities such as thrombopoietin and chemokine (C-C motif) ligand 3 may be useful tools in clinical practice.
The biology, clinical phenotype and progression rate of chronic myelomonocytic leukemia (CMML) are highly variable due to diverse initiating and secondary clonal genetic events. To determine the ...effects of molecular features including clonal hierarchy in CMML, we studied whole-exome and targeted next-generation sequencing data from 150 patients with robust clinical and molecular annotation assessed cross-sectionally and at serial time points of disease evolution. To identify molecular lesions unique to CMML, we compared it to the related myeloid neoplasms (N=586), including juvenile myelomonocytic leukemia, myelodysplastic syndromes (MDS) and primary monocytic acute myeloid leukemia and discerned distinct molecular profiles despite similar pathomorphological features. Within CMML, mutations in certain pathways correlated with clinical classification, for example, proliferative vs dysplastic features. While most CMML patients (59%) had ancestral (dominant/co-dominant) mutations involving TET2, SRSF2 or ASXL1 genes, secondary subclonal hierarchy correlated with clinical phenotypes or outcomes. For example, progression was associated with acquisition of new expanding clones carrying biallelic TET2 mutations or RAS family, or spliceosomal gene mutations. In contrast, dysplastic features correlated with mutations usually encountered in MDS (for example, SF3B1 and U2AF1). Classification of CMML based on hierarchies of ancestral and subclonal mutational events may correlate strongly with clinical features and prognosis.
We hypothesized that specific molecular mutations are important biomarkers for response to DNA methyltransferase inhibitors (DNMT inhibitors) and may have prognostic value in patients with ...myelodysplastic syndromes (MDS). Mutational analysis was performed in 92 patients with MDS and related disorders who received 5-azacytidine (n=55), decitabine (n=26) or both (n=11). Mutational status was correlated with overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) by univariate and multivariate analysis. Risk stratification models were created. TET2, DNMT3A, IDH1/IDH2, ASXL1, CBL, RAS and SF3B1 mutations were found in 18, 9, 8, 26, 3, 2 and 13% of patients, respectively. In multivariate analysis, TET2(MUT) and/or DNMT3A(MUT) (P=0.03), platelets > or = 100 × 10(9)/l (P=0.007) and WBC<3.0 × 10(9)/l (P=0.03) were independent predictors of better response. TET2(MUT) and/or DNMT3A(MUT) (P=0.04) status was also independently prognostic for improved PFS, as were good or intermediate cytogenetic risk (P<0.0001), age<60 (P=0.0001), treatment with both 5-azacytidine and decitabine (P=0.02) and hemoglobin > or = 10 g/dl (P=0.01). Better OS was associated with ASXL1(WT) (P=0.008) and SF3B1(MUT) (P=0.01), and, similar to PFS, cytogenetic risk (P=0.0002), age (P=0.02) and hemoglobin (P=0.04). These data support the role of molecular mutations as predictive biomarkers for response and survival in MDS patients treated with DNMT inhibitors.
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.
PDF
