SIES Award | Neutrophil extracellular traps in myeloproliferative neoplasms: impact of cytoreductive therapy

Background. NETs may contribute to immunothrombosis in myeloproliferative neoplasms (MPNs), a complex process driven by the interaction between the innate immune system and the coagulation cascade. Investigating NETs in MPNs and their potential as biomarkers may provide insights for improving disease management.Aims. To assess the association between H3.1 nucleosomes, as a surrogate of NETs, and clinical characteristics of MPN patients, and to evaluate the effect of cytoreductive therapy on H3.1 nucleosome levels.Methods. In this monocentric, prospective study, plasma samples were collected before and after therapy. H3.1 nucleosome levels were measured using the Nu.Q® NETs Immunoassay from 50 μL of K2EDTA plasma.Results. Forty-two patients were included (50% female): 9 (21%) with essential thrombocythaemia (ET), 18 (43%) with polycythaemia vera (PV), 10 (24%) with primary myelofibrosis (PMF), and 5 (12%) with secondary MF. Baseline samples were obtained from untreated patients (median age 57 years, range 18–77) after a median of 14 months from diagnosis. Overall, 34 (81%) were JAK2V617F, 5 (12%) CALR, 2 (5%) MPL mutated and 1 (2%) was triple negative. JAK2VAF was available in 15 (median 25%, range 7.4–87). Nine (21%) had a prior thrombosis (5 arterial, 4 venous), occurring a median of 45 months before sampling; only 4 were on anticoagulants. Fourteen (33%) had splenomegaly.Baseline H3.1 nucleosome levels varied across MPN subtypes (p