Impact of bone marrow fibrosis grade in post-polycythemia vera and post-essential thrombocythemia myelofibrosis: A study of the MYSEC group

Incidence of blast phase in myelofibrosis according to anemia severity

Myelofibrosis (MF) is a clonal malignancy frequently characterized by anemia and in 10%-20% of cases it can evolve into blast phase (BP). Anemia in MF is associated with reduced survival and -in primary MF- also with an increased probability of BP. Conventional treatments for anemia have limited effectiveness in MF. Within a dataset of 1752 MF subjects largely unexposed to ruxolitinib (RUX), BP incidence was 2.5% patients per year (p-y). This rate reached respectively 4.3% and 4.5% p-y in case of patients with common terminology criteria for adverse events (CTCAE) grade 3/4 and grade 2 anemia, respectively, that represented together 32% of the cohort. Among 273 MF cases treated with RUX, BP incidence was 2.89% p-y and it reached 4.86% p-y in subjects who started RUX with CTCAE grade 2 anemia (one third of total). Within patients with red blood cell transfusion-dependency at 6 months of RUX (21% of the exposed), BP rate was 4.2% p-y. Our study highlights a relevant incidence of BP in anemic MF patients, with a similar rate whether treated with or without RUX. These findings will help treating physicians to make decisions on the safety profile of innovative anemia treatments.

SOHO State of the Art Updates and Next Questions | Polycythemia Vera: Is It Time to Rethink Treatment?

Polycythemia vera (PV) is a Philadelphia-negative myeloproliferative neoplasm characterized by excessive myeloid cells production, mostly secondary to mutations in the Janus kinase 2 (JAK2) gene. PV natural history might be burdened by thrombotic events (TEs) and evolution into post-PV myelofibrosis (PPV-MF) or blast phase (BP). To date, no treatment strategies have been shown to have disease modifying effects, so therapy is directed at preventing TEs. All patients require phlebotomies (PHLs) to keep hematocrit below 45% and once-daily low dose aspirin (if not contraindicated). Apart from patients at "high risk" because of age over 60 years or a thrombosis history, cytoreductive therapies (CT) should be given to patients with relevant signs of myeloproliferation or intolerance to PHLs. Approved choices both for first and second line CT are hydroxyurea (HU) and pegylated forms of interferon (peg-IFN), the latter probably being better for young patients, and subjects without critical and recent vascular events or massive splenomegaly. The JAK1/2 inhibitor ruxolitinib is the treatment of choice in case of resistance/intolerance to HU, with proved efficacy in terms of thrombotic prevention. Data are too preliminary to consider CT for "low risk" PV cases, but ropeg-IFN is being studied in this setting with a short follow-up. A careful monitoring for signs of evolution into PPV-MF is fundamental for optimizing patient management.

Towards a Personalized Definition of Prognosis in Philadelphia-Negative Myeloproliferative Neoplasms

Purpose of Review

Philadelphia-negative myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), prefibrotic (pre-), and overt-primary myelofibrosis (primary MF, PMF). PV and ET could evolve into secondary MF (SMF), whose early diagnosis relies on monitoring signs of possible progression. All MPNs have a risk of blast phase (BP), that is associated with a very dismal outcome. Overall survival (OS) is different among MPNs, and disease-specific prognostic scores should be applied for a correct clinical management. In this review, an overview of current prognostic scores in MPNs will be provided.

Recent Findings

The biological complexity of MPNs and its role on the trajectory of disease outcome have led to the design of integrated prognostic models that are nowadays of common use in PMF patients. As for PV and ET, splicing gene mutations could have a detrimental role, but with the limit of the not routinary recommended application of extensive molecular analysis in these diseases. SMF is recognized as a distinct entity compared to PMF, and OS estimates should be calculated by the MYSEC-PM (Myelofibrosis SECondary-prognostic model). Both in PMF and SMF, decisions as selection of patients potentially candidates to allogenic stem cell transplant or that could benefit from an early shift from standard treatment are based not only on conventional prognostic scores, but also on multivariable algorithms.

Summary

The expanding landscape of risk prediction for OS, evolution to BP, and SMF progression from PV/ET informs personalized approach to the management of patients affected by MPNs.

Prediction of thrombosis in post-polycythemia vera and post-essential thrombocythemia myelofibrosis: a study on 1258 patients

Patients with Philadelphia-negative myeloproliferative neoplasms are at high risk of thrombotic events (TEs). Predisposing factors have been identified in essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (primary MF, PMF), while yet not recognized in post PV/ET-MF (known as secondary MF, SMF). Within the 1258 SMF of the MYSEC (MYelofibrosis SECondary to PV and ET) dataset, 135 (10.7%) developed a TE at a median follow-up of 3.5 years (range, 1-21.4), with an incidence of 2.3% patients per year. Venous events accounted for two-thirds of the total. Cox multivariable analysis, supported by Fine-Gray models with death as competitive risk, showed that being on cytoreductive therapy at time of SMF evolution is associated with an absolute risk reduction of thrombosis equal to 3.3% within 3 years. Considering individually cytoreductive therapies, univariate regression model found that both conventional cytoreduction, mainly hydroxyurea, (HR 0.41, 95% CI: 0.26-0.65, p = 0.0001) and JAK inhibitors, mostly ruxolitinib, (HR 0.50, 95% CI: 0.24-1.02, p = 0.05) were associated with fewer thrombosis. Our study informs treating physicians of a non-low incidence of TEs in post PV/ET-MF and of the potential protective role of cytoreductive therapy in terms of thrombotic events.