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Myeloproliferative neoplasms (MPN) are characterized by a clonal proliferation of myeloid lineage cells within the bone marrow. The classical BCR-ABL negative MPNs are comprised of polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. Historically, the majority of MPNs are diagnosed in adults older than 60 years of age; however, in recent years, there has been recognition of MPNs in the adolescent and young adult (AYA) population. AYAs with MPN, typically defined as between the ages of 15 and 39 years old, may comprise up to 20% of patients diagnosed with MPN. They demonstrate unique patterns of driver mutations and thrombotic events and remain at risk for progression to more aggressive disease states. Given the likely long length of time they will live with their disease, there is a significant unmet need in identifying well-tolerated and effective treatment options for these patients, particularly with the advent of disease modification. In this review, we provide a comprehensive overview of the clinical features, disease course and management of AYA patients with MPN and, in doing so, highlight key characteristics that distinguish them from their older counterparts., (© 2024 British Society for Haematology and John Wiley & Sons Ltd.)

Fedratinib, an oral Janus kinase-2 (JAK2) inhibitor, is approved for patients with myelofibrosis (MF) and platelet counts ≥50 × 10 9 /l, based on outcomes from the phase 3, placebo-controlled JAKARTA trial in JAK-inhibitor-naïve MF, and the phase 2, single-arm JAKARTA2 trial in patients previously treated with ruxolitinib. We evaluated the efficacy and safety of fedratinib 400 mg/day in patients with baseline platelet counts 50 to <100 × 10 9 /l ("Low-Platelets" cohorts), including 14/96 patients (15%) in JAKARTA and 33/97 (34%) in JAKARTA2. At 24 weeks, spleen response rates were not significantly different between the Low-Platelets cohort and patients with baseline platelet counts ≥100 × 10 9 /l ("High-Platelets" cohort), in JAKARTA (36% vs. 49%, respectively; p = 0.37) or JAKARTA2 (36% vs. 28%; p = 0.41). Symptom response rates were also not statistically different between the Low- and High-Platelets cohorts. Fedratinib was generally well-tolerated in both platelet-count cohorts. New or worsening thrombocytopaenia was more frequent in the Low-Platelets (44%) versus the High-Platelets (9%) cohort, but no serious thrombocytopaenia events occurred. Thrombocytopaenia was typically managed with dose modifications; only 3/48 Low-Platelets patients discontinued fedratinib due to thrombocytopaenia. These data indicate that fedratinib 400 mg/day is safe and effective in patients with MF and low pretreatment platelet counts, and no initial fedratinib dose adjustment is required for these patients., (© 2022 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Myeloproliferative neoplasms (MPN) are mainly sporadic but inherited variants have been associated with higher risk development. Here, we identified an EPOR variant (EPOR P488S ) in a large family diagnosed with JAK2 V617F -positive polycythaemia vera (PV) or essential thrombocytosis (ET). We investigated its functional impact on JAK2 V617F clonal amplification in patients and found that the variant allele fraction (VAF) was low in PV progenitors but increase strongly in mature cells. Moreover, we observed that EPOR P488S alone induced a constitutive phosphorylation of STAT5 in cell lines or primary cells. Overall, this study points for searching inherited-risk alleles affecting the JAK2/STAT pathway in MPN., (© 2022 British Society for Haematology and John Wiley & Sons Ltd.)

We assessed the diagnostic performances of erythropoietin and JAK2 mutations in 1,090 patients with suspected polycythemia who were referred for red cell mass (RCM) measurement. In patients with a high haematocrit and/or haemoglobin level, a low erythropoietin level (<=3·3 mUI/ml) and JAK2 mutation showed comparable positive predictive value (PPV) for true polycythemia (RCM>=125%), 92·1% and 90% respectively. A very-low erythropoietin level (<=1·99 mUI/ml) had a PPV of 100% for polycythemia vera (PV) diagnosis. We confirmed the correlations between RCM, erythropoietin and JAK2 variant allelic frequency in PV patients. This study prompts the need to revisit the role of EPO in PV diagnostic criteria., (© 2021 British Society for Haematology and John Wiley & Sons Ltd.)

Myeloproliferative neoplasm-related myelofibrosis is associated with cytopenic or proliferative phases, splenomegaly and constitutional symptoms. Few effective treatments are available and small series suggested that interferon could be an option for myelofibrosis therapy. We performed a retrospective study of pegylated-interferon α-2a (Peg-IFNα-2a) therapy in myelofibrosis. Sixty-two patients treated with Peg-IFNα-2a at 17 French and Belgian centres were included. Responses were determined based on the criteria established by the International Working Group for Myelofibrosis Research and Treatment. Mean follow-up was 26 months. Sixteen of 25 anaemic patients (64%) (eight concomitantly receiving recombinant erythropoietin) achieved a complete response and transfusion-independence was obtained in 5/13 patients (38·5%). Constitutional symptoms resolved in 82% of patients. All five leucopenic patients normalized their leucocyte counts, whereas a normal platelet count was obtained in 5/8 thrombocytopenic patients. Splenomegaly was reduced in 46·5% of patients, and complete resolution of thrombocytosis and leucocytosis were observed in 82·8% and 68·8% of patients, respectively. Side effects (mostly haematological) were mainly of grade 1-2. The only factor independently associated with treatment failure was a spleen enlargement of more than 6 cm below the costal margin. In conclusion, Peg-IFNα-2a induced high response rates with acceptable toxicity in a large proportion of patients with primary and secondary myelofibrosis, especially in early phases., (© 2013 John Wiley & Sons Ltd.)

Patients with myelofibrosis (MF) have significant debilitating symptoms, physical disabilities, and poor health-related quality of life (HRQoL). Here, we report post-hoc analyses of the impact of ruxolitinib, a potent and selective JAK1 and JAK2 inhibitor, on disease-related symptoms and HRQoL in MF patients from the large phase 3 COMFORT-II study (N = 219). During the follow-up period of 48 weeks, HRQoL and MF-associated symptoms improved from baseline for ruxolitinib-treated patients but remained the same or worsened for best available therapy (BAT)-treated patients. Based on the European Organization for Research and Treatment of Cancer QoL Questionnaire core 30 items (EORTC QLQ-C30), treatment-induced differences in physical and role functioning, fatigue, and appetite loss significantly favoured ruxolitinib versus BAT from week 8 (P < 0·05) up to week 48 (P < 0·05). Ruxolitinib resulted in significantly higher response rates in global health status/QoL and Functional Assessment of Cancer Therapy-Lymphoma (FACT-Lym) summary scores versus BAT at most time points (P < 0·05). Significant improvements in the Lymphoma subscale (including symptoms of pain, fever, itching, fatigue, weight loss, loss of appetite, and other patient concerns), FACT-General, FACT-Lym trial outcome index, and FACT-Lym total were also observed with ruxolitinib versus BAT starting at week 8 and continuing thereafter. Overall, these data demonstrated that ruxolitinib improved HRQoL in MF patients and further support the use of ruxolitinib for the treatment of symptomatic MF., (© 2013 John Wiley & Sons Ltd.)

Myeloproliferative disorders (MPD) are reported in 25-65% of patients with splanchnic vein thrombosis (SVT). Diagnostic criteria for MPD have not been fully established in this context. Using clusters of abnormal megakaryocytes in bone marrow (BM) biopsy as a reference standard for Philadelphia negative MPD, we assessed the relevance of other criteria currently recommended for the diagnosis of MPD in SVT (128 consecutive SVT patients). First, usual criteria were compared with BM results: endogenous erythroid colony formation (EEC) was strongly correlated with BM results; splenomegaly, blood cell count, total red cell volume, erythropoietin level and cytogenetic were much less accurate. Then, patients were assigned to three groups according to the combination of BM and EEC findings (group I: both present; group II: both absent; group III: other patients); clinical presentation and outcome were compared in each group. At a mean follow-up of 6.09 +/- 6.6 years, progression to a severe form of MPD occurred in 7 of 31 group I patients (23%), in 1 of 34 group III patients (3%) and 0 of 63 group II patients. The combination of marked splenomegaly and platelet count >200 x 10(9)/l was restricted to groups I and III. In conclusion, in patients with SVT, BM findings and EEC allowed the diagnosis of MPD at risk of aggravation. Marked splenomegaly in association with platelet counts >200 x 10(9)/l constitute a simple index with high specificity but low sensitivity.

CD16 antibodies recognize Fcgamma receptors III of a and b types. In a patient with severe idiopathic aplastic anaemia (AA), polymorphonuclear cells, which in normal subjects express FcgammaRIIIb, were found to be CD16 negative. The FcgammaRIIIb gene configuration was analysed by PCR on peripheral blood mononuclear cells. Bi-allelic deletion encompassing at least part of the coding exon 5 was found in the patient and his brother, suggesting a hereditary defect. The patient underwent successful bone marrow transplantation from his HLA-matched brother despite a similar phenotype and genotype. This observation suggests that FcgammaRIIIb hereditary deficiency in donor and/or recipient does not impair engraftment and justifies the use of other monoclonal antibodies in addition to CD16 in the study of GPI-anchored antigen expression.

Spontaneous megakaryocytic colonies (CFU-MK) formation without the addition of Meg-CSA in myeloproliferative disorders (MPD) has been reported by many laboratories. The mechanism by which this occurs is still unknown. In our previous work we have found that the spontaneous colonies persisted in serum-free agar culture although the colony cells were smaller and the colony numbers fewer than in plasma clot culture and that monoclonal antibodies against IL3, IL6 and GM-CSF had no inhibitory effect on spontaneous CFU-MK in both semisolid cultures. Recently, proto-oncogene c-mpl and c-mpl ligand, thrombopoietin (TPO), have been shown to specifically participate in the regulation of normal human megakaryocytopoiesis. In order to test the hypothesis that c-mpl, c-mpl ligand pathway is involved in the spontaneous growth of megakaryocyte progenitors, we investigated mRNA expressions of c-mpl and TPO in cells grown in serum-free liquid culture using RT-PCR. The c-mpl expression was detected in the cultured cells from all nine patients (six with ET, two with PV, one with PMF) who had spontaneous CFU-MK in clonal assays. However, none of the patients expressed TPO mRNA in these cells. Pre-incubation of nonadherent mononuclear cells with thioester-modified antisense oligodeoxynucleotide to c-mpl at a concentration of 6 microM significantly decreased the cloning efficiency of spontaneous megakaryocyte growth by 42.5% (P < 0.05) in plasma clot assay (seven with ET, one with PV) and 69.6% (P < 0.05) in serum-free agar culture (six with ET, one with PV). In control experiments the introduction of a scrambled oligomer to antisense oligodeoxynucleotide had no such effect on spontaneous colony formation. These results indicate that c-mpl exerts an important effect in the growth of spontaneous megakaryocytopoiesis in MPD.