Noon Conference 5/17/2022: MPNs

Myeloproliferative neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders that are quite distinct from myelodysplastic syndromes. Here to shed light on these diagnoses is hematologist and oncologist Dr. Michael Choi.

Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia chromosome, t(9;22), which results in BCR-ABL1 fusion. It can be divided into the chronic phase (<10% blasts), accelerated phase (10-29%), and blast phase (30%+). Treatment is with tyrosine kinase inhibitors (TKIs)— imatinib (the OG TKI), dasatinib, nilotinib, or ponatinib—which inhibit BCR-ABL1 fusion protein function. Allogeneic hematopoietic stem cell transplantation is an option for patients with accelerated- or blast-phase disease.

Polycythemia vera (PV) presents as increased RBC mass and is classically associated with the JAK2 V617F mutation. Therapeutic phlebotomy is used to target a hematocrit goal of <45%, and iron supplementation is avoided even when deficient. Essential thrombocythemia (ET) presents as thrombocytosis and thrombosis; it is also associated with JAK2 mutations, though mutations in calreticulin (CALR) and thrombopoietin receptor (MPL) can also lead to ET. Low-dose aspirin is given to patients with PV and ET to lower the thrombotic risk. Depending on patient’s risk, cytoreductive therapy with agents such as hydroxyurea and ruxolitinib may also be indicated for treatment of PV and ET.

Hypereosinophilic syndrome (HES) is diagnosed when a patient presents with a sustained eosinophilia >1500/μL and evidence of resultant end-organ damage. Most cases result from mutations in platelet-derived growth factor receptors.

Primary myelofibrosis (PMF) generally has the worst prognosis among all MPNs. Patients have bone marrow fibrosis, ectopic hematopoiesis, and massive splenomegaly. Treatment options are limited and often involves allogeneic stem cell transplantation.

Thank you, Dr. Choi, for this very high-yield discussion of MPNs! Great job, Dr. Janna Raphelson, one of our RACE Track residents, for helping create the session!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.