Key Points• More than half of patients with PV or ET harbor DNA mutations/ variants other than JAK2/CALR/MPL.• The presence of some of these mutations adversely affects overall, leukemia-free, or myelofibrosis-free survival.Polycythemia vera (PV) is characterized by JAK2 and essential thrombocythemia (ET) by JAK2, calreticulin (CALR), and myeloproliferative leukemia virus oncogene (MPL) mutations; we describe the occurrence and prognostic relevance of DNA sequence variants/mutations other than JAK2/CALR/MPL. A myeloid neoplasm-relevant 27-gene panel was used for nextgeneration sequencing of bone marrow or whole blood DNA and conventional tools were used for analysis. "Adverse variants/mutations" were identified by age-adjusted multivariable analysis of impact on overall, leukemia-free, or myelofibrosis-free survival. Fifty-three percent of 133 Mayo Clinic patients with PV and 53% of 183 with ET harbored 1 or more sequence variants/mutations other than JAK2/CALR/MPL; the most frequent were TET2 and ASXL1. "Adverse variants/mutations" in PV included ASXL1, SRSF2, and IDH2 and in ET SH2B3, SF3B1, U2AF1, TP53, IDH2, and EZH2; combined prevalence was 15% and 15%, respectively. Adverse variants/mutations were associated with inferior survival in both PV (median, 7.7 vs 16.9 years) and ET (median, 9 vs 22 years) and the effect was independent of conventional prognostic models with respective hazard ratio (95% confidence interval) of 2.8 (1.5-5.1) and 2.6 (1.4-4.8); these observations were validated in 215 Italian patients with PV and 174 with ET. In both Mayo Clinic and Italian cohorts, leukemic or fibrotic progression was also predicted by adverse variants/mutations. Number of mutations did not provide additional prognostic information. We conclude that targeted deep sequencing in PV and ET allows for genetic risk stratification that is independent of clinically derived prognostic models.

Atypical chronic myeloid leukemia (aCML) is an aggressive myeloid neoplasm with overlapping features of myelodysplastic syndromes (prominent granulocytic dysplasia) and myeloproliferative neoplasms (neutrophilic leukocytosis). We studied 25 molecularly-annotated and World Health Organization defined aCML patients; median age 70 years, 84% males. Cytogenetic abnormalities were seen in 36% and gene mutations in 100%. Mutational frequencies were, ASXL1 28%, TET2 16%, NRAS 16%, SETBP1 12%, RUNX1 12%, ETNK1 8% and PTPN11 4%. Fifteen patients (60%) had >1 mutation, while 9 (36%) had ≥3. The median overall survival (OS) was 10.8 months and at last follow up (median 11 months), 17 (68%) deaths and 2 (8%) leukemic transformations were documented. On univariate analysis, survival was adversely impacted by advanced age (p=0.02), low hemoglobin (p=0.01), red blood cell transfusion dependence (p=0.03), high white blood cell count (p=0.02), TET2 (p=0.03), NRAS (p=0.04), PTPN11 (p=0.02) mutations and the presence of ≥3 gene mutations (p=0.006); ASXL1, SETBP1, and ETNK1 mutations did not impact OS. In multivariable analysis, advanced age (p=0.003) [age >67: HR 10.1, 95% CI 1.3–119], low hemoglobin (p=0.008) [HB< 10gm/dl: HR 8.2, 95% CI 1.6–23.2] and TET2 mutations (p=0.01) [HR 8.8, 95% CI 1.6–47.7] retained prognostic significance. We then used age >67 years, hemoglobin <10 gm/dl and the presence of TET2 mutations (each counted as one risk factor) to create a hazard ratio weighted prognostic model; effectively stratifying patients into two risk categories, low (0–1 risk factor) and high (≥2 risk factors), with median OS of 18 and 7 months respectively.

In a recent International Working Group on Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) study, prior arterial events and hypertension were predictors of subsequent arterial thrombosis whereas prior venous events and age ≥65 years predicted venous thrombosis in polycythemia vera (PV). In the current study, we sought to validate the above findings and identify additional predictors of arterial versus venous thrombosis. At a median follow up of 109 months, thrombosis after diagnosis occurred in 128 (22%) patients; 82 (14%) arterial and 57 (10%) venous events. On multivariate analysis, prior arterial events (<0.0001), hyperlipidemia (p = 0.03), and hypertension (p = 0.02) predicted subsequent arterial events. In comparison, prior venous events (p = 0.05), leukocytosis ≥11 × 109/L (p = 0.002), and major hemorrhage (p = 0.02) were predictors of subsequent venous events. Salient associations with arterial thrombosis included age ≥ 60 years, hypertension, diabetes, hyperlipidemia and normal karyotype whereas age ≤ 60 years, females, palpable splenomegaly and history of major hemorrhage were associated with venous thrombosis. TET2 or ASXL1 mutations did not impact arterial nor venous thrombosis. In conclusion, we identify distinct associations for arterial versus venous thrombosis in PV and confirm that a prior arterial or venous thrombotic event is the most reliable predictor of subsequent events.

DNMT3A mutations are seen in~5% of patients with chronic myelomonocytic leukemia (CMML) and thus far, have had an indeterminate prognostic impact on survival. We carried out this study to assess the prognostic impact of DNMT3A mutations on a larger informative cohort of CMML patients (n 5 261). DNMT3A mutations were seen in 6% (n 5 16); 56% (n 5 9) male, with a median age of 64 years. Eighty-one % of DNMT3A mutations were missense, with the Arg882 mutational hot spot accounting for 63% of all changes. Five (31%) patients had an abnormal karyotype whereas concurrent gene mutations (SF3B1/SRSF2/U2AF1256%, TET2250%, and ASXL1225%) were seen in all patients. Apart from a higher frequency of SF3B1 (P 5 0.0001) and PTPN11 (P 5 0.005) mutations and a lower frequency of SRSF2 (P 5 0.004) mutations, there were no significant differences between DNMT3A mutated patients and their wildtype counterparts. In univariate analysis, survival was shorter in DNMT3A mutated (median 8 months) versus wildtype (median 27 months) patients (P 5 0.0007; HR 2.9, 95% CI 1.5-5.7); with other variables of significance including lower hemoglobin (P 5 0.002), higher leukocyte count (P 5 0.0009), higher monocyte count (P 5 0.0012), circulating blast % (P 5 0.001), circulating immature myeloid cells (P 5 0.01), bone marrow blast % (P 5 0.045), abnormal karyotype (P 5 0.02), and ASXL1 (P 5 0.01) mutations. In a multivariable model that included the aforementioned variables, when both DNMT3A and ASXL1 mutations were added, only DNMT3A (P < 0.0001) and ASXL1 (P 5 0.004) mutations remained significant. DNMT3A mutations were also predictive of a shortened leukemia-free survival. These findings warrant inclusion of DNMT3A mutations in molecularly integrated CMML prognostic models.

One-hundred Mayo Clinic patients with high/intermediate-risk myelofibrosis (MF) received momelotinib (MMB; JAK1/2 inhibitor) between 2009 and 2010, as part of a phase 1/2 trial (NCT00935987); 73% harbored JAK2 mutations, 16% CALR, 7% MPL, 44% ASXL1, and 18% SRSF2. As of July 2017, MMB was discontinued in 91% of the patients, after a median treatment duration of 1.4 years. Grade 3/4 toxicity included thrombocytopenia (34%) and liver/pancreatic test abnormalities (<10%); grade 1/2 peripheral neuropathy occurred in 47%. Clinical improvement (CI) occurred in 57% of patients, including 44% anemia and 43% spleen response. CI was more likely to occur in ASXL1-unmutated patients (66% vs 44%) and in those with <2% circulating blasts (66% vs 42%). Response was more durable in the presence of CALR type 1/like and absence of very high-risk karyotype. In multivariable analysis, absence of CALR type 1/like (HR 3.0; 95% CI 1.2–7.6) and presence of ASXL1 (HR 1.9; 95% CI 1.1–3.2) or SRSF2 (HR 2.4, 95% CI 1.3–4.5) mutations adversely affected survival. SRSF2 mutations (HR 4.7, 95% CI 1.3–16.9), very high-risk karyotype (HR 7.9, 95% CI 1.9–32.1), and circulating blasts ≥2% (HR 3.9, 95% CI 1.4–11.0) predicted leukemic transformation. Post-MMB survival (median 3.2 years) was not significantly different than that of a risk-matched MF cohort not receiving MMB.