Elala, Yoseph C

Abstract Systemic mastocytosis (SM) is a clinically heterogeneous disease with prognosis chiefly assigned based on World Health Organization (WHO) morphologic subclassification. We assessed the feasibility of developing contemporary risk models for SM based on clinical and integrated clinical-genetics information. Diagnosis of SM was per WHO criteria, and karyotype and next-generation sequencing data were available in a subset of the total 580 patients (median age, 55 years; range, 18-88 years) seen at the Mayo Clinic between 1968 and 2015. Morphologic subcategories were indolent/smoldering in 291 (50%) and “advanced” in 289 (50%): SM with an associated hematological neoplasm in 199, aggressive SM in 85, and mast cell leukemia in 5. Multivariable analysis of clinical variables identified age >60 years, advanced SM, thrombocytopenia <150 × 109/L, anemia below sex-adjusted normal, and increased alkaline phosphatase (ALP) as independent risk factors for survival; respective hazard ratios (HRs) 95% confidence intervals (95% CIs) were 2.5 (1.9-3.4), 2.7 (1.8-4.0), 2.5 (1.9-3.4), 2.2 (1.6-3.1), and 2.1 (1.5-3.0). In addition, ASXL1 (HR, 4.5; 95% CI, 2.6-7.6), RUNX1 (HR, 4.3; 95% CI, 1.3-10.8), and NRAS (HR, 5.0, 95% CI, 1.5-13.2) mutations were independently associated with inferior survival. Combined clinical, cytogenetic, and molecular risk factor analysis confirmed the independent prognostic contribution of adverse mutations (2.6, 1.6-4.4), advanced SM (4.0, 1.8-10.0), thrombocytopenia (2.8, 1.7-4.5), increased ALP (2.1, 1.2-4.0), and age >60 years (2.2, 1.3-3.6). These data were subsequently used to develop clinical and hybrid clinical-molecular risk models. The current study advances 2 complementary risk models for SM and highlights the independent prognostic contribution of mutations.

About 85% of patients with essential thrombocythemia (ET) harbor one of three driver mutations: JAK2, calreticulin (CALR), and MPL; the remaining ( ∼15%) are wild type for all three mutations and are referred to as being “triple negative.” Furthermore, CALR mutations in ET are structurally classified as type 1/type 1‐like or type 2/type 2‐like variants. The objective of the current study was to examine the impact of CALR mutation variant stratified driver mutational status on overall (OS), myelofibrosis‐free (MFFS), thrombosis‐free, and leukemia‐free survival (LFS) in ET; 495 patients (median age 58 years; 61% females) with ET were fully annotated for the their driver mutational status: 321 (65%) harbored JAK2, 109 (22%) CALR, and 12 (2%) MPL mutations and 11% were triple‐negative. Among the 109 CALR‐mutated cases, 52% were classified as type 1/type 1‐like and 48% as type 2/type 2‐like. In univariate analysis, triple‐negative patients displayed the best and MPL mutated the worst OS (P = 0.007); however, the difference in OS was no longer apparent on multivariable analysis that included age and sex as covariates (P = 0.5). LFS was also similar among the different mutational groups (P = 0.6) whereas MFFS was significantly shorter in MPL‐mutated patients on both univariate and multivariable analyses (age‐adjusted P = 0.02; HR 7.9, 95% CI 2.0–31.5). Also in multivariable analysis that included thrombosis history, age, and cardiovascular risk factors, the presence of JAK2 or MPL mutations was independently associated with higher risk of thrombosis (P = 0.02; HR 1.9, 95% CI 1.1–3.4). In conclusion, driver mutational status in ET does not appear to influence overall or LFS, even after CALR variant stratification. However, the presence of MPL mutations might be associated with a higher risk of fibrotic transformation and the presence of JAK2/MPL mutations with higher risk of thrombosis. Am. J. Hematol. 91:503–506, 2016. © 2016 Wiley Periodicals, Inc.

The primary objective of treatment in essential thrombocythemia (ET) is to prevent thromboembolic complications. In this regard, advanced age and thrombosis history have long distinguished “low” from “high” risk patients. More recently, JAK2V617F and cardiovascular (CV) risk factors were identified as additional modifiers, leading to the development of a 3‐tiered International Prognostic Score of Thrombosis for ET (IPSET‐thrombosis): “low,” “intermediate,” and “high”. The international data set used to develop IPSET‐thrombosis was recently re‐analyzed in order to quantify the additional pro‐thrombotic effect of JAK2V617F and CV risk factors in specific risk subcategories. The revised IPSET‐thrombosis identified four risk categories based on three adverse variables (thrombosis history, age >60 years and JAK2V617F): very low (no adverse features), low (presence of JAK2V617F), intermediate (age >60 years) and high (presence of thrombosis history or presence of both advanced age and JAK2V617F). In this study of 585 patients with ET (median age 68 years; 61% female), we validated the revised IPSET‐thrombosis by confirming significant differences in thrombosis risk between “very low” and “low” (HR 2.4, 95% CI 1.1 − 5.3) and between “intermediate” and “high” (HR 2.3, 95% CI 1.1 − 5.2) risk patients. Furthermore, in multivariable analysis, only JAK2V617F (HR=1.8, CI= 1.07 − 2.94) and history of thrombosis (HR=2.1, CI= 1.20 − 3.58) were independently predictive of future thrombotic events. The revised IPSET‐thrombosis needs confirmation in prospective studies, especially in terms of risk‐adapted therapy that includes the need for aspirin therapy in very low risk, twice‐daily aspirin therapy for low risk and cytoreductive therapy for low or intermediate risk patients. Am. J. Hematol. 91:390–394, 2016. © 2016 Wiley Periodicals, Inc.