SummaryA phase II A study was conducted to evaluate the safety and efficacy of Givinostat, a novel Histone-Deacetylases inhibitor, in patients with Polycythaemia Vera (PV, n = 12), Essential Thrombocythaemia (ET, n = 1) and Myelofibrosis (n = 16), bearing the JAK2V617F mutation. The study was approved by the local ethics committees and all human participants gave written informed consent. Givinostat was given orally for 24 weeks at a starting dose of 50 mg twice daily. The median treatment duration was 20 weeks. Reasons for treatment discontinuation were disease progression (n = 6), grade 2 thrombocytopenia (n = 1), psychiatric symptoms (n = 1) and withdrawn consent (n = 2). A dose reduction was applied in 10 patients while a temporary interruption occurred in 15. Among 13 PV/ET patients, 1 complete, 6 partial and 4 no responses were documented at study end while 2 patients went off-study, prematurely. Three major responses were registered among 16 MF patients. Pruritus disappeared in most patients and reduction of splenomegaly was observed in 75% of PV/ET and 38% of MF patients. Reverse transcription polymerase chain reaction identified a trend to reduction of the JAK2V617F allele burden. Givinostat was well tolerated and could induce haematological response in most PV and some MF patients.

A total of 410 patients with blast phase myeloproliferative neoplasm (MPN-BP) were retrospectively reviewed: 248 from the Mayo Clinic and 162 from Italy. Median survival was 3.6 months, with no improvement over the last 15 years. Multivariable analysis performed on the Mayo cohort identified high risk karyotype, platelet count < 100 × 109/L, age > 65 years and transfusion need as independent risk factors for survival. Also in the Mayo cohort, intensive chemotherapy resulted in complete remission (CR) or CR with incomplete count recovery (CRi) rates of 35 and 24%, respectively; treatment-specified 3-year/5-year survival rates were 32/10% for patients receiving allogeneic stem cell transplant (AlloSCT) (n = 24), 19/13% for patients achieving CR/CRi but were not transplanted (n = 24), and 1/1% in the absence of both AlloSCT and CR/CRi (n = 200) (p < 0.01). The survival impact of AlloSCT (HR 0.2, 95% CI 0.1–0.3), CR/CRi without AlloSCT (HR 0.3, 95% CI 0.2–0.5), high risk karyotype (HR 1.6, 95% CI 1.1–2.2) and platelet count < 100 × 109/L (HR 1.6, 95% CI 1.1–2.2) were confirmed to be inter-independent. Similar observations were made in the Italian cohort. The current study identifies the setting for improved short-term survival in MPN-BP, but also highlights the limited value of current therapy, including AlloSCT, in securing long-term survival.

The optimal duration of treatment with vitamin K antagonists (VKA) after venous thromboembolism (VTE) in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) is uncertain. To tackle this issue, we retrospectively studied 206 patients with MPN-related VTE (deep venous thrombosis of the legs and/or pulmonary embolism). After this index event, we recorded over 695 pt-years 45 recurrences, venous in 36 cases, with an incidence rate (IR) of 6.5 per 100 pt-years (95% confidence interval (CI): 4.9-8.6). One hundred fifty-five patients received VKA; the IR of recurrent thrombosis per 100 pt-years was 4.7 (95% CI: 2.8-7.3) on VKA and 8.9 (95% CI: 5.7-13.2) off VKA (P=0.03). In patients receiving VKA, the IR of recurrent thrombosis per 100 pt-years was 5.3 (95% CI: 3.2-8.4) among 108 patients on long-term VKA and 12.8 (95% CI: 7.3-20.7) after discontinuation among the 47 who ceased treatment (P=0.008), with a doubled risk of recurrence after stopping VKA (hazard ratio: 2.21, 95% CI: 1.19-5.30). The IR of major bleeding per 100 pt-years was 2.4 (95%: CI: 1.1-4.5) on VKA and 0.7 (95% CI: 0.08-2.5) off VKA (P=0.08). In conclusion, in MPN patients with VTE recurrent thrombosis is significantly reduced by VKA and caution should be adopted in discontinuation; however, the incidence of recurrence on treatment remains high, calling for clinical trials aimed to improve prophylaxis in this setting.

Yacoub et al report excellent responses to pegylated interferon alfa-2a in patients with hydroxyurea-resistant/intolerant polycythemia vera or essential thrombocythemia.