Association between JAK2V617F variable allele frequency and risk of thrombotic events in patients with myeloproliferative neoplasms.

BACKGROUND: Myeloproliferative neoplasms (MPNs) are a group of chronic disorders of the bone marrow characterised by the overproduction of clonal myeloid stem cells. The most common driver mutation found in MPNs is a point mutation on exon 14 of the JAK2 gene, JAK2V617F. Various studies have suggested that measuring the variable allele frequency (VAF) of JAK2V617F may provide useful insight regarding diagnosis, treatment, risks and outcomes in MPN patients. In particular, JAK2V617F has been associated with increased risk of thrombotic events, a leading cause of mortality in MPNs. AIMS: The aim of this study was to determine if JAK2V617F VAF was associated with clinical outcomes in patients with MPN. METHODS: JAK2V617F VAF was determined by quantitative PCR (qPCR) in a cohort of 159 newly diagnosed MPN patients, and the association of JAK2V617F VAF and risk of thrombosis was examined in this cohort. RESULTS: We observed a significantly higher JAK2V617F VAF in PV and PMF versus ET. A significant association was observed between JAK2V617F VAF and risk of thrombotic events. When patients were stratified by thrombotic events prior to and post diagnosis, an association with JAK2V617F VAF was only observed with post diagnosis thrombotic events. Of note, these associations were not observed when looking at each MPN subtype in isolation. CONCLUSIONS: We have shown that a higher JAK2V617F VAF is associated with thrombotic events post MPN diagnosis. JAK2V617F VAF may therefore provide a valuable prognostic indicator for risk of thrombosis in MPNs.

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.

(32)P in the treatment of myeloproliferative disorders.

UNLABELLED: (32)P has been available for the treatment of myeloproliferative neoplasms (MPNs) for over seventy years. It was first used in 1938 by John H Lawrence in the treatment of polycythaemia and chronic leukaemias. With the introduction of agents such as hydroxycarbamide, interferon and anagrelide the role of (32)P has been diminished. Today, Polycythaemia Rubra Vera (PRV) and Essential Thrombocythaemia (ET) remain the only myeloproliferative conditions in which (32)P is indicated. MATERIALS AND METHODS: We carried out a retrospective review of all patients who had received 32P in Northern Ireland over a 24 year period. The time to successful response, duration of response, and associated complications were reviewed. RESULTS: (32)P was successful in inducing remission in 90% of patients. This remission was sustained following one dose without the need for further therapy in 37% of cases. 47% required repeated doses. 26% required recommencement of alternative therapies. No cases of thrombosis, myelofibrosis or acute leukaemia were observed. DISCUSSION: We conclude that (32)P is a well-tolerated and efficacious treatment option in the elderly. We discuss our results compared with previous work in this area. (32)P will continue to be offered to elderly patients in our practice.

Novel antibodies directed against the human erythropoietin receptor: creating a basis for clinical implementation.

Recombinant human erythropoietin (rHuEPO) is an effective treatment for anaemia but concerns that it causes disease progression in cancer patients by activation of EPO receptors (EPOR) in tumour tissue have been controversial and have restricted its clinical use. Initial clinical studies were flawed because they used polyclonal antibodies, later shown to lack specificity for EPOR. Moreover, multiple isoforms of EPOR caused by differential splicing have been reported in cancer cell lines at the mRNA level but investigations of these variants and their potential impact on tumour progression, have been hampered by lack of suitable antibodies. The EpoCan consortium seeks to promote improved pathological testing of EPOR, leading to safer clinical use of rHuEPO, by producing well characterized EPOR antibodies. Using novel genetic and traditional peptide immunization protocols, we have produced mouse and rat monoclonal antibodies, and show that several of these specifically recognize EPOR by Western blot, immunoprecipitation, immunofluorescence, flow cytometry and immunohistochemistry in cell lines and clinical material. Widespread availability of these antibodies should enable the research community to gain a better understanding of the role of EPOR in cancer, and eventually to distinguish patients who can be treated safely by rHuEPO from those at increased risk from treatment.

Insight into the pathogenesis of chronic lymphocytic leukemia (CLL) through analysis of IgVH gene usage and mutation status in familial CLL.

To address the proposition that familial B-cell chronic lymphocytic leukemia (CLL) may exhibit a more restricted phenotype than sporadic CLL with respect to immunoglobulin gene usage or ontogenic development, we compared immunoglobulin (Ig) heavy chain variable region (VH) gene usage and IgVH mutation status in 327 patients with CLL from 214 families with 724 patients with sporadic cases. The frequency of mutated CLL was higher in familial CLL (P < .001), and there was evidence of intrafamilial concordance in mutation status (P < .001). The repertoire and frequency of IgVH usage was, however, not significantly different between familial and sporadic CLL. Furthermore, IgVH usage was not correlated between affected members of the same family. These observations provide evidence that familial CLL is essentially indistinguishable from sporadic CLL, favoring a genetic basis to disease development in general rather than a simple environmental etiology.

Comparison of diagnostic criteria for polycythaemia vera.

Three sets of diagnostic criteria for polycythaemia vera (PV); the Polycythaemia Vera Study Group (PVSG) criteria (1975), the British Committee for Standards in Haematology (BCSH) criteria (1996) and the World Health Organisation (WHO) criteria (2001) have been described. We compared the ability of each set of criteria to accurately diagnose PV and differentiate it from secondary, apparent and idiopathic erythrocytosis. A cohort was drawn from a clinical database of erythrocytosis patients currently attending the Belfast City Hospital and the relevant information from the time of diagnosis for each patient was assessed according to each set of criteria, with the BCSH criteria used as a comparator. Sufficient data was available on 71 patients: 46 PV, 8 idiopathic, 8 apparent and 9 secondary erythrocytosis. The BCSH criteria classified 34 of 46 patients (73.9%) as PV and the WHO criteria had a sensitivity and specificity of 100% for classifying PV. For idiopathic and apparent erythrocytosis, the specificity of the WHO criteria, compared to the BCSH criteria, declined to 66.7 and 87.5%, respectively. The PVSG criteria were limited by the unavailability of required data for some patients resulting in a sensitivity and specificity of 50% for PV and specificity of 100% for all other groups. The Janus kinase 2 (JAK2) V617F mutation was present in 34 (85.3%) PV, 2 (50%) IE, 1 (50%) apparent and no secondary erythrocytosis cases. We concluded that the BCSH criteria were the most accurate diagnostic criteria for PV as they had an acceptable level of sensitivity and could differentiate between PV and other erythrocytoses.

Acute onset dysphagia associated with an intramural oesophageal haematoma in acquired haemophilia.

A 78-year-old man presented with a 5-day history of epistaxis and spontaneous bruising, and a 2-day history of acute dysphagia. Barium swallow, computerized tomography scan of the chest and upper gastrointestinal endoscopy were suggestive of an upper oesophageal tumour, although biopsies failed to confirm this. Investigations including a raised activated partial thromboplastin time led to the detection of an inhibitor causing functional factor VIII deficiency. Following treatment with intravenous human immunoglobulin, oral prednisolone and oral cyclophosphamide, the patient's dysphagia resolved. There was a resolution of the findings seen at the initial endoscopy and on computerized tomography scan of the chest, consistent with an oesophageal haematoma. Follow-up endoscopy failed to detect recurrence or an aetiological factor.