A practical approach to patient monitoring, with a focus on assessing treatment efficacy and individualized patient care.
Prithviraj Bose: Monitoring for PV really depends on the patient as far as how frequently to do so. I see most of my PV patients every three months, but certainly I could be seeing somebody every month or even every two weeks, depending on how proliferative the disease is. When I see them, I'm getting labs, which is, you know, a CBC, of course, because remember that hematocrit under 45% is the most important goal in PV. And then I'm also looking at the white count, not so much at the platelets in terms of control, because there's very poor correlation between the platelet count and the thrombotic risk. So that's probably less important for me, but I'm definitely looking at all those labs. Obviously, you also want to make sure that you're not creating any metabolic complications with your therapies and looking at liver enzymes. For example, with interferon, liver enzymes can go up, stuff like that. The spleen should be assessed. Spleen is generally assessed by palpation. I don't think in PV, too many of us are getting routine imaging, even in MF, actually, mostly in clinical practice, we use palpation. We should always ask about symptoms. I think the best way of asking about symptoms is to administer the MPN-SAF-TSS form, which is really, sounds like a mouthful, but really an easy, intuitive, quick form with 10 questions that is widely available. And we've started to actually integrate that into the electronic health record. So an objective way of measuring symptoms and following symptoms over time. Now regarding when a patient should be assessed as perhaps not responding and that their therapy should be switched. Generally, this refers to patients on hydroxyurea because far and away, that's the most common frontline treatment for PV, I think around the world. But of course, now we are getting interesting new data. ruxolitinib has been there for the last almost nine years as an option in the second line. And we are now available to use, we are now able to use newer interferon. So I think this becomes a very relevant question. So what I would say is that I go up on the hydroxyurea dose before I switch therapy and I go up to 2000 and no more because I go by the ELN criteria [00:36:00] of hydroxyurea failure, resistance, and intolerance. But hydroxyurea at high doses can be difficult to tolerate. So as I alluded to before, some patients will just be intolerant to hydroxyurea and I would encourage use of the ELN criteria because those give you a nice framework for what is resistance, what is intolerance. And so again, the goals, of course are controlling that hematocrit under 45, keeping the white cells, ideally under 11 if they have symptoms, which many of them do then improving their quality of life and by controlling those symptoms. Spleen, less so in PV than in MF, but that's another thing we look at. So, again, I typically switch to ruxolitinib in the second line, and I generally am using the ELN criteria to tell me when to do so. Of course, as we've been saying through this conversation today, interferons are now increasingly used. We now have one on label, which is the Ropeg. And but the data with that I view more as a frontline agent. And so I'm offering that, especially in patients who are younger and very interested in long-term disease modification. As I alluded to, we are starting to see some of that data with ruxolitinib as well. So, I think we may be starting to move away in PV from hydroxyurea towards more biologically targeted therapies for the benefits, for these additional benefits beyond count control that we get with hydroxyurea.