Mutational profiling in suspected triple-negative essential thrombocythaemia using targeted next-generation sequencing in a real-world cohort.

Essential thrombocythaemia (ET) is driven by somatic mutations involving the JAK2, CALR and MPL genes. Approximately 10% of patients lack driver mutations and are referred as 'triple-negative' ET (TN-ET). The diagnosis of TN-ET, however, relies on bone marrow examination that is not always performed in routine practice, and thus in the real-world setting, there are a group of cases with suspected TN-myeloproliferativeneoplasm.In this real-world cohort, patients with suspected TN-ET were initially rescreened for JAK2, CALR and MPL and then targeted next-generation sequencing (NGS) was applied.The 35 patients with suspected TN-ET had a median age at diagnosis of 43 years (range 16-79) and a follow-up of 10 years (range 2-28). The median platelet count was 758×109/L (range 479-2903). Thrombosis prior to and following diagnosis was noted in 20% and 17% of patients. Six patients were JAK2V617F and two patients were CALR positive on repeat screening. NGS results showed that 24 of 27 patients harboured no mutations. Four mutations were noted in three patients.There was no evidence of clonality for the majority of patients with suspected TN-ET with targeted NGS analysis. Detection of driver mutations in those who were previously screened suggests that regular rescreening is required. This study also questions the diagnosis of TN-ET without the existence of a clonal marker.

Effect of Bruton's tyrosine kinase inhibitors on platelet aggregation in patients with acute myocardial infarction.

AIMS: Despite widespread use of dual antiplatelet therapy in acute myocardial infarction, there remains a residual risk of morbidity and mortality. Bruton's Tyrosine Kinase inhibitors have been found to inhibit platelet aggregation through the Glycoprotein VI collagen-mediated pathway. The Bruton's Tyrosine Kinase inhibitor, Ibrutinib is used in the management of haematological malignancies and another Bruton's Tyrosine Kinase inhibitor, ONO-4059 (also known as tirabrutinib), is in clinical development. This is an observational study to evaluate the effects of Ibrutinib and ONO-4059 on platelet aggregation after acute myocardial infarction. METHODS AND RESULTS: Twenty patients with a confirmed diagnosis of acute myocardial infarction were enrolled and blood samples obtained within 48 h of hospital admission. All patients were on dual antiplatelet therapy; aspirin plus a P2Y12 inhibitor (clopidogrel or ticagrelor). Blood samples were treated ex vivo with increasing concentrations of Ibrutinib (0, 0.5, 1, 2 µM) and ONO-4059 (0, 0.2, 0.5, 1 µM). Platelet aggregation was measured in response to collagen using a Multiplate analyser to estimate the area under the curve, with lower values indicating lower platelet aggregation. The median age was 63 years and 80% were male. The median area under the curve values for Ibrutinib concentrations 0 (control), 0.5, 1 and 2 µM were 18.5, 8 (P = 0.0004), 4.5 (P < 0.0001) and 2 (P < 0.0001) units and for ONO-4059 concentrations 0 (control), 0.2, 0.5 and1µM, median area under the curve values were 13, 12 (P = 0.7), 6.5 (P = 0.0001) and 5.5 (P = 0.0004 compared to control). CONCLUSION: The Bruton's Tyrosine Kinase inhibitors, Ibrutinib and ONO-4059, show further inhibition of platelet aggregation in blood samples from patients with acute myocardial infarction, receiving dual antiplatelet therapy in a dose dependent manner. These results provide a rationale for Bruton's Tyrosine Kinase inhibitors to be tested as a potential new antiplatelet strategy for acute myocardial infarction.