Expert Stephen Oh, MD, PhD, provides a broad overview of the myeloproliferative neoplasms: polycythemia vera, essential thrombocythemia, and myelofibrosis.
Stephen Oh, MD, PhD: As far as defining myeloproliferative neoplasms or MPNs, I guess, one important point to cover first is the term MPN. These diseases used to be referred to at myeloproliferative disorders or MPDs. These days, the term is MPN and the N for neoplasm is meant to reflect that these are, in fact, blood cancers. What used to be MPDs are, in fact, MPNs, and that refers to a group of diseases which include three diseases which share a number of features but also are distinct. That includes polycythemia vera or PV, essential thrombocythemia, ET, and myelofibrosis.
Now, polycythemia vera and essential thrombocythemia are similar in many ways. The shared hallmark, amongst others, is elevated blood counts. Thus, in the case of PV, there is increased hemoglobin or erythrocytosis plus or minus increased elevations in the other blood counts, white blood cell count, and platelets. And in essential thrombocythemia, the cardinal abnormality is increased platelets or thrombocytosis. [In] both of those diseases, patients are at risk for both bleeding and clotting and, over time, patients with PV and ET are at risk for evolution to myelofibrosis.
Myelofibrosis can occur as a subsequent complication of PV or ET, but can also occur de novo, essentially, primary myelofibrosis. And that disease is a little bit different from PV and ET in that, rather than elevated hemoglobin, patients with myelofibrosis most typically have anemia, often getting to the point of patients becoming transfusion-dependent, in conjunction with other cytopenias, for instance, thrombocytopenia. And these patients often have quite a substantial symptom burden, including weight loss, fatigue, symptoms related to enlarged spleen and things like that. So these diseases share a number of characteristics, but they’re also distinct.
Transcript edited for clarity.