Citations

Four hundred and nine patients with chronic myelomonocytic leukemia (CMML) were included in the international collaborative study (268 (66%) and 141 (34%) from Mayo clinic and French consortium respectively). Thirty percent displayed an abnormal karyotype, including; 72% sole, 16% two, and 11% complex abnormalities. The most common abnormalities included; +8 (23%), ‐Y (20%), ‐7/7q‐(14%), 20q‐ (8%), +21 (8%), and der(3q) (8%). Patients with an abnormal karyotype were more likely to be elderly (P = 0.03), be anemic (P = 0.0009), have leukocytosis (P = 0.02) with neutrophilia (P = 0.03), demonstrate increased circulating immature myeloid cells (P = 0.0003), peripheral blood blasts (P < 0.0001), and bone marrow blasts (P < 0.0001). ASXL1 (P = 0.04) and SF3B1 (P = 0.03) mutations clustered with an abnormal karyotype, whereas SRSF2 (P = 0.02) mutations occurred more commonly with a normal karyotype. A step‐wise survival analysis resulted in three distinct cytogenetic risk categories: high (complex and monosomal karyotypes), intermediate (all abnormalities not in the high or low risk groups) and low [normal, sole ‐Y and sole der (3q)] with median survivals of 3 [hazard ratio (HR) = 8.1, 95% confidence interval (CI) = 4.6–14.2], 20 (HR = 1.7, 95% CI = 1.2–2.3) and 41 months, respectively. In multivariable analysis, this particular cytogenetic risk stratification remained significant in the context of the Molecular Mayo Model (P < 0.0001), MD Anderson prognostic model (P < 0.0001), the GFM CMML model (P < 0.0001) and was effective in predicting leukemic transformation (P = 0.004). Am. J. Hematol. 89:1111–1115, 2014. © 2014 Wiley Periodicals, Inc.

Abstract Janus kinase-2 (JAK2)/STAT pathway activation is commonly observed in myeloproliferative neoplasms and plays an important role in disease development and progression. The V617F activating mutation in the JAK2 pseudokinase domain is found in 95% of patients with polycythemia vera (PV) and in 50-70% of patients with primary myelofibrosis (MF) or essential thrombocythemia (ET). Studies have shown the clinical efficacy of JAK2 inhibitors in treating MF in terms of a reduction in splenomegaly and relief of constitutional symptoms. A reduction in the JAK2V617F allele burden after treatment with a JAK2-targeted agent could be a surrogate for a disease-modifying effect of this therapy. To demonstrate this, a robust method that can accurately measure the JAK2V617F allele burden is required. Here, we report the development of a sensitive quantitative PCR (qPCR) assay to determine the JAK2V617F allele burden in patients treated with SAR302503, the validation of the assay in a Phase 0 clinical study and implementation in a phase II study using samples from patients with MF. The assay demonstrated robust performance, with high sensitivity (LLOD=0.05% and LLOQ=0.5%) and accuracy. A phase 0 study in MF, PV, and ET patients showed that (1) there was minimal intra-subject sampling variability in JAK2V617F allele burden, and (2) whole-blood samples are stable for at least 48 hours at ambient conditions for DNA preparation without a significant impact on JAK2V617F allele burden measurement.Of the 31 patients with intermediate-2 or high-risk MF enrolled in a phase II clinical study (NCT01420770), baseline samples were available for 29 patients and of these, 26 were JAK2V617F-positive using this assay. Of the 19/26 patients for whom samples were available at all 3 time points, the median allele burden was 93% at baseline, 87% at the end of Cycle 3, and 78% at the end of Cycle 6. Among the 24 patients who were JAK2V617F-positive and for whom spleen measurements were available at the end of Cycle 6, a total of 15 (63%) had a spleen response (≥ 35% reduction in spleen volume by MRI versus baseline). In contrast, two JAK2V617F-negative patients did not have a spleen response. Patients with baseline allele burden levels of 0 to &lt;25%, 25% to 75%, and ≥75% showed spleen response rates of 50%, 44%, and 69%, respectively, at the end of Cycle 6. JAK2V617F allele burden will continue to be assessed every 3 cycles. Longer follow up is needed to determine the clinical effect of allele burden reduction. Citation Format: Feng Liu, Moshe Talpaz, Animesh Pardanani, Catriona Jamieson, Nashat Gabrail, Ayalew Tefferi, Tianlei Lei, Rita Greco, Francisco Adrian, Nikki Daskalakis, Claudia Lebedinsky, Pamela Cohen, Donald Bergstrom. Determination of JAK2V617F allele burden in a phase II study of patients with myelofibrosis treated with SAR302503 using a sensitive and robust allele-specific qPCR assay. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-294. doi:10.1158/1538-7445.AM2013-LB-294

Disease overview: Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by stem cell‐derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.Diagnosis: Diagnosis is based on bone marrow morphology. The presence ofJAK2,CALR, orMPLmutation is supportive but not essential for diagnosis; approximately 90% of patients carry one of these mutations and 10% are “triple‐negative.” None of these mutations are specific to PMF and are also seen in essential thrombocythemia (ET). Prefibrotic PMF mimics ET in its presentation and the distinction, enabled by careful bone marrow morphological examination, is prognostically relevant. Differential diagnosis also includes chronic myeloid leukemia, myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.Risk Stratification: The Dynamic International Prognostic Scoring System‐plus (DIPSS‐plus) uses eight predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocytes >25 × 109/L, circulating blasts ≥1%, constitutional symptoms, red cell transfusion dependency, platelet count <100 × 109/L, and unfavorable karyotype (i.e., complex karyotype or sole or two abnormalities that include +8, −7/7q−, i(17q), inv(3), −5/5q−, 12p−, or 11q23 rearrangement). The presence of 0, 1, “2 or 3,” and ≥4 adverse factors defines low, intermediate‐1, intermediate‐2, and high‐risk disease with median survivals of approximately 15.4, 6.5, 2.9, and 1.3 years, respectively. High risk disease is also defined byCALR−/ASXL1+mutational status.Risk‐Adapted Therapy: Observation alone is adequate for asymptomatic low/intermediate‐1 risk disease, especially withCALR+/ASXL1−mutational status. Stem cell transplant is considered for DIPSS‐plus high risk disease or any risk disease withCALR−/ASXL1+mutational status. Investigational drug therapy is reasonable for symptomatic intermediate‐1 or intermediate‐2 risk disease. Splenectomy is considered for drug‐refractory splenomegaly. Involved field radiotherapy is most useful for post‐splenectomy hepatomegaly, non‐hepatosplenic EMH, PMF‐associated pulmonary hypertension, and extremity bone pain. Am. J. Hematol. 89:916–925, 2014. © 2014 Wiley Periodicals, Inc.

Key Points Survival in ET is superior to that of PV, regardless of mutational status, but remains inferior to the sex- and age-matched US population. JAK2/CALR/MPL mutational status is prognostically informative in PMF, regarding overall and leukemia-free survival.

AbstractBackgroundVascular events in essential thrombocythemia (ET) are associated with advanced age and thrombosis history. Recent information suggests additional effect from the presence of specific mutations.ObjectivesTo examine the influence of age and thrombosis history on the reported association between mutational status and thrombosis‐free survival in ET.Patients and MethodsAnalysis was performed using a Mayo Clinic cohort of 300 ET patients, and key findings were reanalyzed by including additional 102 Italian patients.ResultsAmong 300 Mayo patients with ET (median age 55 yr, 60% females), mutational frequencies were 53% JAK2, 32% CALR, 3% MPL, and 12% JAK2, CALR and MPL wild type. One hundred and six (35%) patients experienced arterial (n = 75) or venous (n = 43) events, before (n = 55) or after (n = 71) diagnosis. In univariate analysis, compared to JAK2‐mutated cases, JAK2, CALR and MPL wild type (HR 0.31, 95% CI 0.11–0.86), and CALR‐mutated (0.53, 95% CI 0.30–0.92) patients displayed better thrombosis‐free survival. JAK2, CALR, and MPL wild type remained significant (P = 0.03; HR 0.32, 95% CI 0.11–0.9) during multivariable analysis that included age (P = 0.01) and thrombosis history (P = 0.0006); a favorable impact from CALR mutations was of borderline significance (P = 0.1; HR 0.62, 95% CI 0.35–1.1), but became significant (P = 0.02) when multivariable analysis including thrombosis history (P = 0.02) was performed on patients younger than 60 yr of age.ConclusionsThe favorable impact of mutational status on thrombosis‐free survival in ET might be most evident for JAK2, CALR, and MPL wild type patients, whereas the favorable effect from CALR mutations might be confined to young patients.

Disease Overview: Chronic neutrophilic leukemia (CNL) is a myeloproliferative neoplasm characterized by sustained, mature neutrophilic leukocytosis, splenomegaly, and bone marrow granulocytic hyperplasia. Diagnosis: Key diagnostic criteria include leukocytosis of >25 × 109/l (of which >80% are neutrophils) with <10% and <1% circulating immature granulocytes and myeloblasts, respectively. There should be no dysplasia, monocytosis, molecular evidence of BCR‐ABL1, PDGFRA, PDGFRB, or FGRF1 rearrangements and no identifiable cause for physiologic neutrophilia or, if present, demonstration of myeloid clonality. Developments in Molecular Genetics: Recently, CNL has been shown to be specifically driven by somatic activating mutations of CSF3R, most commonly CSF3R T618I. As such, the diagnosis of CNL will no longer be one of exclusion only, and revision of the current WHO classification is anticipated to include the molecular criterion of mutated CSF3R. Am. J. Hematol. 89:651–658, 2014. © 2014 Wiley Periodicals, Inc.

CALR (calreticulin) trails JAK 2 as the second most mutated gene in essential thrombocythemia (ET). Mutant CALR in ET is a result of frameshift mutations, caused by exon 9 deletions or insertions; type‐1, 52‐bp deletion (p.L367fs*46), and type‐2, 5‐bp TTGTC insertion (p.K385fs*47) variants constitute more than 80% of these mutations. The current study includes a total of 1027 patients divided into test ( n = 402) and validation ( n = 625) cohorts. Among the 402 ET patients in the test cohort, 227 (57%) harbored JAK 2, 11 (3%) Myeloproliferative leukemia virus oncogene ( MPL ), and 114 (28%) CALR mutations; 12% were wild‐type for all three mutations (i.e., triple‐negative). Among the 114 patients with CALR mutations, 51 (45%) displayed type‐1 and 44 (39%) type‐2 variants; compared to mutant JAK 2, both variants were associated with higher platelet and lower hemoglobin and leukocyte counts. However, male sex was associated with only type‐1 ( P = 0.005) and younger age with type‐2 ( P = 0.001) variants. Notably, platelet count was significantly higher in type‐2 vs. type‐1 CALR ‐mutated patients ( P = 0.03) and the particular observation was validated in the validation cohort that included 111 CALR ‐mutated ET patients ( P = 0.002). These findings, coupled with the recent demonstration of preferential expression of mutant and wild‐type CALR in megakaryocytes, suggest differential effects of CALR variants on thrombopoiesis. Am. J. Hematol. 89:E121–E124, 2014. © 2014 Wiley Periodicals, Inc.

In patients not meeting the required hematocrit (HCT) or hemoglobin (Hb) thresholds according to BCSH and the WHO diagnostic criteria, the diagnosis of masked polycythemia vera (mPV) has been proposed. A comparison of HCT or Hb values with the expression of JAK2V617F, JAK2 exon 12, and CALR mutations in strictly WHO‐defined 257 overt PV and 140 mPV (59 mPV according to BCSH) and 397 patients with essential thrombocythemia (ET) was performed. Hb and HCT thresholds of mPV patients were significantly higher than JAK2V617F ET (P < 0.0001). The best cut‐off for Hb to discriminate JAK2‐mutated ET from PV was 16.5 g/dL for males and 16.0 g/dL for females. For HCT, this was 49% in males and 48% in females. The proportion of patients correctly classified as ET or PV when regarding Hb or HCT levels was 95% in males and 93% in females and 94% in both males and females, respectively. Am. J. Hematol. 89:588–590, 2014. © 2014 Wiley Periodicals, Inc.

SummaryChronic myelomonocytic leukaemia (CMML) is a clonal haematopoietic stem cell disorder with myelodysplastic and myeloproliferative overlap features, and an inherent tendency to transform to acute myeloid leukaemia. Approximately 30% of patients present with clonal cytogenetic abnormalities, while almost 90% have molecular aberrations involving epigenetic regulation, the spliceosome component machinery, tumour suppressor genes and transcription factors/regulators. Numerous prognostic models exist for CMML, with more recent models incorporating prognostic mutations, such as those involving ASXL1. Other variables that seem to consistently affect outcomes include the degree of leucocytosis/monocytosis, anaemia and thrombocytopenia. Allogeneic stem cell transplant remains the only curative option for CMML, while hypomethylating agents can be used for transplant‐ineligible patients or those without suitable stem cell sources. Targeting biological pathways activated in CMML offers potential hope for more effective and less toxic therapies.