Understanding how essential thrombocythemia (ET), polycythemia vera (PV), or myelofibrosis (MF) are connected may be confusing to patients. Dr. John Mascarenhas, an expert in myeloproliferative neoplasms (MPNs), provides an overview of how the conditions are defined and how they may progress from one condition to the next.
Dr. John Mascarenhas is Associate Professor of Medicine at the Icahn School of Medicine at Mount Sinai (ISMMS) and the Director of the Adult Leukemia Program and Leader of Clinical Investigation within the Myeloproliferative Disorders Program at Mount Sinai. Learn more about Dr. Mascarenhas, here.
As we move through today’s program, which is going to cover the three classic MPNs, polycythemia vera, essential thrombocythemia and myelofibrosis. So, for someone who has one of these conditions, can you help us understand how one may progress to the next?
So, these are a very heterogeneous or variable group of diseases that are under an umbrella called the myeloproliferative neoplasm. So, MPNs can really present and behave and have very different clinical courses. So, I think it’s very important for patients to realize that these are rare diseases, that that has a complexity to it because they don’t always have the ability or the privilege to know other patients or people in their lives that may have these diseases. So, it could be very frightening from a level of feeling isolated or alone with a diagnosis like this and not having familiarity, but also, that these are vague diagnoses in the sense that when you have breast cancer, one can kind of conceptualize that there is a mass in the breast, for example, and that that can be staged. It can go to the lymph nodes in the armpit, it could spread below. And people can kind of understand that concept. I think it’s a little bit more challenging when you talk about MPNs because it’s a little bit more abstract.
These diseases are within the bone marrows at diagnosis. So, they’re not staged in a physical way, and they are complex because they can lead to high blood counts, low blood counts, different types of symptoms, and the approaches really have to be personalized. They are all three interrelated because there are commonalities. So, there are certain clinical commonalities and also biologic commonalities. So, for example, the JAK2 mutation, the JAK2V617F mutation is seen in all three diseases. So, it’s not specific to one or the other.
It’s more common in polycythemia vera, but in about 50 percent of patients with ET, and 50 percent of patients with MF, you can see this mutation. So, the mutation alone doesn’t really tell us what the disease is. It just tells us you have one of these diseases. And, there are other mutations. So, a bone marrow biopsy then becomes integral in helping subtype the patient and then create that treatment plan and that outlook that’s specific for that disease.
And as you mentioned, to make it even more complicated, these diseases can overlap not just biologically, but in a continuum. So, patients with ET or polycythemia vera can progress in some cases to myelofibrosis. And, all three diseases in a minority of patients can progress or evolve into acute myeloid leukemia, which is a more aggressive form of bone marrow cancer.