Emerging Agents for Myelofibrosis - Episode 4
Ruben Mesa, MD, FACP, director of the UT Health San Antonio MD Anderson Cancer Center: The goals of treating myelofibrosis need to be individualized. Because it is a life-threatening illness, the first question that needs to be answered and be consistent with our current NCCN [National Comprehensive Cancer Network] guidelines, of which I had a role in establishing, is whether patients should be pursuing a stem cell transplant. Now, for the majority, that answer is no—either on the basis of their age, the risk associated with their disease, the lack of an appropriate donner, or patient choice. But it is a crucial question because my view is that there really are 2 parallel paths: a path pursuing stem cell transplant and a path of utilizing medical therapy to optimize the patient, with benefit, to the greatest that we can.
Moshe Talpaz, MD: There are still significant controversies on how to manage and how to treat myelofibrosis. The first questions are: Should we treat myelofibrosis, or should we observe myelofibrosis without any specific treatment? What should the guideline be to treat, and what is available therapy for myelofibrosis? There is only 1 drug that has been approved by the FDA for the treatment of myelofibrosis. This is ruxolitinib, a JAK1/2 inhibitor that has been in use for several years. This drug has been approved for the relatively more advanced stages of myelofibrosis, ranging from prognostic groups intermediate 1 all the way to high risk. Low-risk patients with myelofibrosis are not approved for the usage of ruxolitinib, at least not formally. Now, the question is: Should low-risk patients be treated with a JAK2 inhibitor, or should we observe this patient? And that’s a subject of controversy. The key question will be whether JAK2 inhibitors prolong survival of patients with myelofibrosis. That being the case, there would clearly be an indication to go to the very early stage to try to prevent its progression and treat them as well. But this has not yet been subjected to a systematic study. Thus, we have to wait until this question is studied in a more extensive way.
John Mascarenhas, MD: So it depends. I mean, I risk-stratify patients I see typically with the Dynamic International Prognostic Scoring System in order to decide whether patients are…risk adverse enough to warrant therapy such as hematopoietic stem cell transplantation or whether their disease is low risk enough to warrant watching and waiting in some cases. So it really depends on a combination of the risk score, the symptom burden, and a discussion with the patient about what their goals are.
So typically when we’re trying to address symptoms, probably the most effective drug that we have to address symptom burden, whether it’s constitutional symptoms, fevers, night sweats, weight loss, or systemic system symptoms like bone pain, abdominal discomfort, itching, headaches, and fatigue, JAK inhibition as a class of agents is the most effective, and ruxolitinib is the only JAK1/2 inhibitor that’s approved. So typically that is the first line of therapy, particularly when trying to address symptoms. And for the most part, most patients who are treated with ruxolitinib in particular have some degree of improvement in their symptom burden. It doesn’t necessarily mean that every patient will have every single symptom disappear in every case. Sometimes some symptoms are improved and others remain somewhat troublesome. In some cases, all symptoms are improved to some degree but still can persist. But with ruxolitinib, it is probably the most effective drug. Definitely the only approved drug that we have that really addresses symptom burden.
Moshe Talpaz, MD: In my experience, which is fairly extensive, I have seen a vast spectrum of patients with myelofibrosis. They can have very few symptoms or can have extensive symptoms. And the patients who clearly require treatment are the patients who are symptomatic, lose weight and lose muscle mass, are severely fatigued, have anemia, have very large spleens, and have pains in the bones and sometimes pain in the spleen. Those patients benefit from therapy. In several situations, the response to a JAK2 inhibitor, particularly when it comes to symptom control, can be absolutely dramatic, and patients can feel better within days and gain a considerable amount of weight, and their quality of life can improve in an absolutely dramatic way.
The question is: Should we treat patients who are asymptomatic with this form of therapy? It’s a JAK2 inhibitor. And the question, as I said earlier, is still debated. If the JAK2 inhibitors offer therapy that goes beyond symptomatic help and beyond just shrinking of the spleen and actually prolongs survival, then it’s probably an indication to treat patients who are asymptomatic. But that is a question, not an answer. This issue has to be addressed in studies to see whether in early disease, we can prolong survival in this situation because, obviously, in this early disease, we do not manage symptoms because the patients don’t have symptoms.