Impact of Mutations in the Epigenetic Regulators on the Presentation and Outcome of Patients with Myeloproliferative Neoplasma

Philadelphia negative Myeloproliferative Neoplasms (MPNs) are a group of disorders characterized by proliferation of one or more cell lines of myeloid origin. They include Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (MF). The hallmark of these disorders is the propensity for thrombosis and/or bleeding as well as transformation into end-stage bone marrow fibrosis or acute myeloid leukemia. In addition, there is a wide variety of clinical presentations that have a significant impact on the quality of life. This heterogeneity in presentation and outcome has not been fully explained yet even in recently described subgroups of MPN with molecular classification that include JAK2 positive and CALR positive MPNs. One potential source of heterogeneity is the differences in the epigenetics. This has been previously well shown in other myeloid neoplasms. Mutations in the epigenetic regulators in patients with MPN have been previously detected, however, no previously study attempted to look for multiple genes regulating the epigenetics and none has investigated the impact on the presentation and outcome in these patients. We therefore planned to screen for the previously described mutations in the epigenetic regulators in patients with MPN in both JAK2 positive and CALR positive and compare the clinical presentation and outcome between patients with any epigenetic regulator mutation (EpigR positive group) and patients with no epigenetic regulator mutation (EpigR negative group). Specifically, we will compare the rates of thrombosis, fibrosis, and demographics and assess the interaction of JAK2 and CALR positivity on the impact of these mutations in the variables specified above. We will prospectively approach patients diagnosed with MPN and followed or referred to Sultan Qaboos University Hospital for the study. Jak2 mutation analysis will be done as a routine test while CALR mutation will be done as part of another investigational study (MREC# 976). Mutation analysis of the entire coding regions of ASXL1, ASXL2, TET1, TET2, EZH2, DNMT3A, CBL, IDH1 and IDH2 genes will be performed using the next generation sequencing (Roche GS Junior). We will use the 2008 World Health Organization classification for MPN for disease definition. Clinical and laboratory data will be collected retrospectively. Proportions will be compared using chi-squared test and logistic regression model will be used to estimate the odds ratio (OR) and adjust for potential confounders. Continuous variables will be compared using Student t-test or Mann-Whitney test if not normally distributed. The ORs will be pooled except if interaction is found when the ORs will be adjusted using Mantel-Haenszel for interaction strata. The sample size is estimated to be 322 patients assuming 12% absolute increase in risk using 80% power and an alpha level of 0.05. All descriptive and analytical statistics will be done using STATA 13 software. The study carries minimal risk as only blood sampling is involved. Data will be kept strictly confidential and the ethical approval from the appropriate boards will be sought.