Key Points• Mutation profiling has a high predictive value for identifying individuals with, or at high risk of developing, a myeloid neoplasm.• Patients with clonal cytopenia have a significantly higher risk of developing a myeloid neoplasm than those with no evidence of clonality.Unexplained blood cytopenias, in particular anemia, are often found in older persons. The relationship between these cytopenias and myeloid neoplasms like myelodysplastic syndromes is currently poorly defined. We studied a prospective cohort of patients with unexplained cytopenia with the aim to estimate the predictive value of somatic mutations for identifying subjects with, or at risk of, developing a myeloid neoplasm. The study included a learning cohort of 683 consecutive patients investigated for unexplained cytopenia, and a validation cohort of 190 patients referred for suspected myeloid neoplasm. Using granulocyte DNA, we looked for somatic mutations in 40 genes that are recurrently mutated in myeloid malignancies. Overall, 435/683 patients carried a somatic mutation in at least 1 of these genes. Carrying a somatic mutation with a variant allele frequency ‡0.10, or carrying 2 or more mutations, had a positive predictive value for diagnosis of myeloid neoplasm equal to 0.86 and 0.88, respectively. Spliceosome gene mutations and comutation patterns involving TET2, DNMT3A, or ASXL1 had positive predictive values for myeloid neoplasm ranging from 0.86 to 1.0. Within subjects with inconclusive diagnostic findings, carrying 1 or more somatic mutations was associated with a high probability of developing a myeloid neoplasm during follow-up (hazard ratio 5 13.9, P < .001). The predictive values of mutation analysis were confirmed in the independent validation cohort. The findings of this study indicate that mutation analysis on peripheral blood granulocytes may significantly improve the current diagnostic approach to unexplained cytopenia and more generally the diagnostic accuracy of myeloid neoplasms. (Blood. 2017;129(25):3371-3378)

Key Points• Risk assessment is crucial in patients with CMML because survival may range from a few months to several years.• Integrating clinical features, morphology, and genetic lesions significantly improves risk stratification in CMML.Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative neoplasm with variable clinical course. To predict the clinical outcome, we previously developed a CMML-specific prognostic scoring system (CPSS) based on clinical parameters and cytogenetics.In this work, we tested the hypothesis that accounting for gene mutations would further improve risk stratification of CMML patients. We therefore sequenced 38 genes to explore the role of somatic mutations in disease phenotype and clinical outcome. Overall, 199 of 214 (93%) CMML patients carried at least 1 somatic mutation.Stepwise linear regression models showed that these mutations accounted for 15% to 24% of variability of clinical phenotype. Based on multivariable Cox regression analyses, cytogenetic abnormalities and mutations in RUNX1, NRAS, SETBP1, and ASXL1 were independently associated with overall survival (OS). Using these parameters, we defined a genetic score that identified 4 categories with significantly different OS and cumulative incidence of leukemic evolution. In multivariable analyses, genetic score, red blood cell transfusion dependency, white blood cell count, and marrow blasts retained independent prognostic value. These parameters were included into a clinical/molecular CPSS (CPSS-Mol) model that identified 4 risk groups with markedly different median OS (from >144 to 18 months, hazard ratio [HR] 5 2.69) and cumulative incidence of leukemic evolution (from 0% to 48% at 4 years, HR 5 3.84) (P < .001). The CPSS-Mol fully retained its ability to risk stratify in an independent validation cohort of 260 CMML patients. In conclusion, integrating conventional parameters and gene mutations significantly improves risk stratification of CMML patients, providing a robust basis for clinical decision-making and a reliable tool for clinical trials.

Key Points Using a sensitive method, the MYD88 (L265P) mutation is detectable in all patients with Waldenström’s macroglobulinemia, therefore representing a hallmark of the disease. MYD88 (L265P) is also found in a substantial proportion of patients with IgM-MGUS.

The somatically acquired V600E mutation of the BRAF gene has been recently described as a molecular marker of hairy cell leukemia (HCL). We developed an allele-specific PCR for this mutation and studied 62 patients with HCL, 1 with HCL variant, 91 with splenic marginal zone lymphoma, 29 with Waldenström macroglobulinemia, and 57 with B-cell chronic lymphoproliferative disorders. The BRAF V600E mutation was detected in all HCL cases and in only 2 of the remaining 178 patients. These 2 subjects had B-cell chronic lymphoproliferative disorders that did not fulfill the diagnostic criteria for HCL. Despite the positive PCR finding, the mutation could not be detected by Sanger sequencing in these 2 cases, suggesting that it was associated with a small subclone. We conclude that the BRAF V600E mutation is present in all patients with HCL and that, in combination with clinical and morphologic features, represents a reliable molecular marker for this condition.

The genetic basis of myelodysplastic syndromes (MDS) is heterogeneous, and various combinations of somatic mutations are associated with different clinical phenotypes and outcomes. Whether the genetic basis of MDS influences the outcome of allogeneic hematopoietic stem-cell transplantation (HSCT) is unclear. Patients and MethodsWe studied 401 patients with MDS or acute myeloid leukemia (AML) evolving from MDS (MDS/ AML). We used massively parallel sequencing to examine tumor samples collected before HSCT for somatic mutations in 34 recurrently mutated genes in myeloid neoplasms. We then analyzed the impact of mutations on the outcome of HSCT. ResultsOverall, 87% of patients carried one or more oncogenic mutations. Somatic mutations of ASXL1, RUNX1, and TP53 were independent predictors of relapse and overall survival after HSCT in both patients with MDS and patients with MDS/AML (P values ranging from .003 to .035). In patients with MDS/AML, gene ontology (ie, secondary-type AML carrying mutations in genes of RNA splicing machinery, TP53-mutated AML, or de novo AML) was an independent predictor of posttransplantation outcome (P = .013). The impact of ASXL1, RUNX1, and TP53 mutations on posttransplantation survival was independent of the revised International Prognostic Scoring System (IPSS-R).Combining somatic mutations and IPSS-R risk improved the ability to stratify patients by capturing more prognostic information at an individual level. Accounting for various combinations of IPSS-R risk and somatic mutations, the 5-year probability of survival after HSCT ranged from 0% to 73%. ConclusionSomatic mutation in ASXL1, RUNX1, or TP53 is independently associated with unfavorable outcomes and shorter survival after allogeneic HSCT for patients with MDS and MDS/AML. Accounting for these genetic lesions may improve the prognostication precision in clinical practice and in designing clinical trials.

We analyzed MYD88 and CXCR4 mutation status of 260 patients with Waldenström macroglobulinemia or IgM monoclonal gammopathy of undetermined significance using allele-specific real time quantitative polymerase chain reaction and Sanger sequencing, respectively. A subgroup of 119 patients was further studied with next-generation sequencing of 11 target genes (MYD88, CXCR4, ARID1A, KMT2D, NOTCH2, TP53, PRDM1, CD79B, TRAF3, MYBBP1A, and TNFAIP3). MYD88 (L265P) was found at diagnosis in 91% of patients with Waldenström macroglobulinemia and in 60% of patients with IgM monoclonal gammopathy of undetermined significance using allele-specific polymerase chain reaction analysis. MYD88 mutations other than the classical L265P (V217F, S219C and M232T) were found in four cases by next-generation sequencing. Waldenström macroglobulinemia patients with wild-type MYD88 had a distinct clinical phenotype characterized by less bone marrow infiltration (P=0.01) and more frequent extramedullary involvement (P=0.001) compared to patients with mutated MYD88. Patients with wild-type MYD88 did not show additional mutations in the other target genes. CXCR4 mutations were found by Sanger sequencing in 22% of patients with Waldenström macroglobulinemia. With next-generation sequencing, a CXCR4 mutation was detected in 23% of patients with Waldenström macroglobulinemia and 9% of those with IgM monoclonal gammopathy of undetermined significance. Asymptomatic Waldenström macroglobulinemia patients harboring a CXCR4 mutation had a shorter treatment-free survival (51 months) than that of patients with wild-type CXCR4 (median not reached) (P=0.007). Analysis of variant allele frequencies indicated that CXCR4 mutations were present in the dominant clone in the majority of cases. Recurrent somatic mutations of KMT2D were found in 24% of patients with Waldenström macroglobulinemia and 5% of patients with IgM monoclonal gammopathy of undetermined significance and were primarily subclonal.

Antigen stimulation may be important for splenic marginal zone lymphoma pathogenesis. To address this hypothesis, the occurrence of stereotyped B-cell receptors was investigated in 133 SMZL (26 HCV+) compared with 4,414 HCDR3 sequences from public databases. Sixteen SMZL (12%) showed stereotyped BCR; 7 of 86 (8%) SMZL sequences retrieved from public databases also belonged to stereotyped HCDR3 subsets. Three categories of subsets were identified: i) "SMZL-specific subsets" (n=5), composed only of 12 SMZL (9 HCV-from our series); ii) "Non-Hodgkin's lymphoma-like subsets" (n=5), comprising 5 SMZL (4 from our series) clustering with other indolent lymphomas; iii) "CLL-like subsets" (n=6), comprising 6 SMZL (3 from our series) that belonged to known CLL subsets (n=4) or clustered with public CLL sequences. Immunoglobulin 3D modeling of 3 subsets revealed similarities in antigen binding regions not limited to HCDR3. Overall, data suggest that the pathogenesis of splenic marginal zone lymphoma may involve also HCVunrelated epitopes or an antigenic trigger common to other indolent lymphomas.

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