JAK2V617F, CALR, and MPL Mutations and Bone Marrow Histology in Patients with Essential Thrombocythaemia

Essential thrombocythaemia: A contemporary approach with new drugs on the horizon

Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia. ET patients have traditionally been stratified into two thrombosis risk categories based on age older than 60 years and a history of thrombosis. More recently, the revised IPSET-thrombosis scoring system, which accounts for the increased risk linked to the JAK2 mutation, has been incorporated into most expert recommendations. However, there is increasing evidence that the term ET encompasses different genomic entities, each with a distinct clinical course and prognosis. Moreover, the effectiveness and toxicity of cytoreductive and anti-platelet treatments differ depending on the molecular genotype. While anti-platelets and conventional cytoreductive agents, mainly hydroxycarbamide (hydroxyurea), anagrelide and pegylated interferon, remain the cornerstone of treatment, recent research has shed light on the effectiveness of novel therapies that may help improve outcomes. This comprehensive review focuses on the evolving landscape of treatment strategies in ET, with an emphasis on the role of molecular profiling in guiding therapeutic decisions. Besides evidence-based management according to revised IPSET-thrombosis stratification, we also provide specific observations for those patients with CALR-, MPL-mutated and triple-negative ET, as well as cases with high-risk mutations.

Low-risk polycythemia vera and essential thrombocythemia: management considerations and future directions

Thrombotic events are a distinctive feature of the myeloproliferative neoplasms (MPNs) polycythemia vera (PV) and essential thrombocythemia (ET). Patients with these MPNs may also experience a poor quality of life secondary to symptom burden, as well as progression of disease to acute leukemia or myelofibrosis. Over the years, various risk stratification methods have evolved in order to attempt to predict thrombotic risk, which is the largest contributor of morbidity and mortality in these patients. More than half of PV and ET patients are low- or intermediate-risk disease status at the time of diagnosis. While therapeutic development is presently focused on high-risk patients, there is a paucity of therapies, outside of aspirin and therapeutic phlebotomy, which can reduce the thrombotic risk or delay disease progression in low-risk patients. In this review, we first describe the various complications that patients with PV and ET experience, and then detail our evolving understanding of risk stratification in these diseases. We then highlight the available evidence on the management of low-risk PV and ET and include a description of novel therapies currently under investigation in this space. We conclude with recommendations for future directions to advance our understanding and improve the treatment of low-risk PV and ET.

Artificial intelligence-based morphological fingerprinting of megakaryocytes: a new tool for assessing disease in MPN patients

Accurate diagnosis and classification of myeloproliferative neoplasms (MPNs) requires integration of clinical, morphological, and genetic findings. Despite major advances in our understanding of the molecular and genetic basis of MPNs, the morphological assessment of bone marrow trephines (BMT) is critical in differentiating MPN subtypes and their reactive mimics. However, morphological assessment is heavily constrained by a reliance on subjective, qualitative, and poorly reproducible criteria. To improve the morphological assessment of MPNs, we have developed a machine learning approach for the automated identification, quantitative analysis, and abstract representation of megakaryocyte features using reactive/nonneoplastic BMT samples (n = 43) and those from patients with established diagnoses of essential thrombocythemia (n = 45), polycythemia vera (n = 18), or myelofibrosis (n = 25). We describe the application of an automated workflow for the identification and delineation of relevant histological features from routinely prepared BMTs. Subsequent analysis enabled the tissue diagnosis of MPN with a high predictive accuracy (area under the curve = 0.95) and revealed clear evidence of the potential to discriminate between important MPN subtypes. Our method of visually representing abstracted megakaryocyte features in the context of analyzed patient cohorts facilitates the interpretation and monitoring of samples in a manner that is beyond conventional approaches. The automated BMT phenotyping approach described here has significant potential as an adjunct to standard genetic and molecular testing in established or suspected MPN patients, either as part of the routine diagnostic pathway or in the assessment of disease progression/response to treatment.