Dr. Srdan Verstovsek provides an overview of myeloproliferative neoplasm (MPN) progression and reviews indicators that essential thrombocythemia (ET), polycythemia vera (PV) or myelofibrosis may progress.
Dr. Srdan Verstovsek:
When we talk about ET and PV, they should be life-long conditions without much of a change. It’s uncontrolled blood cell count and thromboembolic events, which are then subject to a therapy, and the goal of therapy is to decrease the thromboembolic risk.
There is still, in some smaller proportion of the patients, a risk of a disease change on its own. We talk about the genetic testing that can reveal a change in genetic complexity of the disease, which may be responsible for a change down the road. Or abnormalities in chromosomes that can be seen at the time of diagnosis in some of the patients with ET and PV, not very often, which may predispose patients to a change down the road, a change to more aggressive condition.
So, a smaller proportion of the patients, perhaps 10 – 20 percent of the patients between ET and PV, can over time, long time, acquire fibers in the bone marrow.
That can lead to anemia actually, progressive increases in spleen, bone marrow cells in blood, that would be then a change to myelofibrosis. And a very small percent of the patients actually can change to acute myeloid leukemia, with the baby cells in the blood and the bone marrow, these are called blasts.
They should not be in the blood in the wrong person. They should be below 5 percent in bone marrow in normal person, but if they go above 20 percent, we call that acute leukemia.
So, transformation of ET or PV to myelofibrosis or acute myeloid leukemia, are fear, and obviously can lead to a shorter life expectancy. And so, one can certainly worry about that, but again, it is in a smaller proportion of the patients, and we don’t usually worry that much about it. However, the worry does exist, that’s why you are asking me about it, and the problem is we don’t have medication that would be known and proven in prevention of that biological change of the disease in some patients.
In myelofibrosis it’s similar situation, 20 – 25 percent of the patients change to acute myeloid leukemia, and we don’t have real medication that would be preventing that change.