Who is typically prescribed JAK2 inhibitors?

Who is typically prescribed JAK2 inhibitors, and at what stage of myelofibrosis treatment are they used?

A part that I should explain prior to answering that question is about how we risk stratify some of these patients. When we take a look at a newly diagnosed myelofibrosis patient, whether or not it's a primary myelofibrosis or coming from a prior polycythemia vera or essential thrombocythemia patient, we try to risk stratify them. One of the risks that we're worried about in practice is progression to other forms of blood cancers, including acute leukemia. And some of these systems that we've implemented and evaluated in many cohorts help us risk stratify who's higher or lower risk for progression to acute leukemia. There are many risk stratification systems, and the truth is it is hard to know which one is optimal. One of the more important risk stratification systems is called the DIPSS score, or the dynamic international prognostic scoring system. The DIPSS scoring system encapsulates five important aspects of the patient's presentation. Number one, age over 65. Their hemoglobin if it's less than ten grams per deciliter. Their white blood cell count if it's above 25,000 per microliter. Their presence of leukemia cells or blasts in their peripheral blood, as well as if the patient has constitutional symptoms. Based on these five points, we can say that a patient has low, intermediate, or high-risk disease. So to answer your question about which patients benefit from the JAK inhibitors, traditionally we think of the patients that have DIPSS intermediate two or higher disease, concurrently with symptoms associated with myelofibrosis. But the truth is, in my clinical practice, even patients with allegedly low-risk disease with symptoms including splenomegaly, I do still consider starting on a JAK inhibitor for a better quality of life for these patients.