Post-PV myelofibrosis (spent phase)

Over one to two decades a minority of PV patients progress to post-PV myelofibrosis: marrow fibrosis, falling haemoglobin, a large spleen, constitutional symptoms and sometimes transformation to acute leukaemia. Risk rises with age, duration of disease, high white cell counts and additional mutations such as ASXL1 and SRSF2. Management follows myelofibrosis: JAK inhibitors for spleen and symptoms, momelotinib for anaemia, and allogeneic stem cell transplant for fit higher-risk patients. Preventing this transition is the main long-term goal of PV research.