Oncogenic gene expression and epigenetic remodeling of cis-regulatory elements in ASXL1-mutant chronic myelomonocytic leukemia

Myeloid neoplasms are clonal hematopoietic stem cell disorders driven by the sequential acquisition of recurrent genetic lesions. Truncating mutations in the chromatin remodeler ASXL1 (ASXL1MT) are associated with a high-risk disease phenotype with increased proliferation, epigenetic therapeutic resistance, and poor survival outcomes. We performed a multi-omics interrogation to define gene expression and chromatin remodeling associated with ASXL1MT in chronic myelomonocytic leukemia (CMML). ASXL1MT are associated with a loss of repressive histone methylation and increase in permissive histone methylation and acetylation in promoter regions. ASXL1MT are further associated with de novo accessibility of distal enhancers binding ETS transcription factors, targeting important leukemogenic driver genes. Chromatin remodeling of promoters and enhancers is strongly associated with gene expression and heterogenous among overexpressed genes. These results provide a comprehensive map of the transcriptome and chromatin landscape of ASXL1MT CMML, forming an important framework for the development of novel therapeutic strategies targeting oncogenic cis interactions

JAK2V617F mutation screening as part of the hypercoagulable work-up in the absence of splanchnic venous thrombosis or overt myeloproliferative neoplasm: assessment of value in a series of 664 consecutive patients

The JAK2V617F mutation is recurrent in polycythemia vera and essential thrombocythemia, which are myeloproliferative neoplasms (MPNs) frequently associated with arterial and/or venous thromboembolism. More recently, the JAK2V617F mutation has been identified as a surrogate marker for subclinical or occult clonal myeloproliferation in patients with splanchnic venous thrombosis. However, information is limited regarding JAK2V617F-associated thrombosis outside the splanchnic district in patients without overt MPN. To address this issue, we retrospectively studied a consecutive series of 664 such patients who experienced thrombotic events characteristic of an MPN (500 with venous thromboembolism, 136 with stroke, and 28 with myocardial infarction at a young age). The JAK2V617F mutation was detected in only 6 (\u3c1.0%) patients (5 with recurrent venous thromboembolism and 1 with stroke), and the mutant allele burden was low in all instances (range, 2.2%-7.5%). None of these 6 patients developed either overt MPN or recurrent thrombosis after a median follow-up of 40 months. We conclude that the prevalence of the JAK2V617F mutation in patients with nonsplanchnic venous thrombosis in the absence of MPN is too low to warrant mutation screening as part of the hypercoagulable work-up. Our study also suggests that the natural history of a JAK2V617F-positive occult MPN might be different from that of a typical MPN