Aaron Gerds, MD: The tenets of treating patients with polycythemia vera [PV] are low-dose daily aspirin, as well as reductive therapy in high-risk patients to keep the hematocrit under 45%. Focusing on that last point, the subtle reductive therapies are systemic therapies that we do to keep the hematocrit under 45% in patients with polycythemia vera, including hydroxyurea, interferon, as well as ruxolitinib. And these different therapies, again, have the main goal of reducing the hematocrit to less than 45%, a number that is based on the results of the CYTO-PV trial [NCT01645124], and do so by different mechanisms. And so they all have pluses and minuses.

The hydroxyurea slows DNA synthesis, so it slows down erythroid production directly. It can also help control white blood cell counts and platelet counts quite well. This drug has been around for a very long time and is considered a standard of care in the treatment of patients with high-risk polycythemia vera. Interferons have been around for a long time. It’s unclear exactly how they work. I know there are a lot of mechanisms that have been postulated, but it is a biologic agent, and so it may have some additional immune effects there. But it is clear that interferons can control hematocrit as well as the other counts quite well, and that may have a deeper impact on disease.

We often see a reduction in allele burdens, which is a very exciting thing to see the mutation amounts going down in patients and even some patients getting into molecular remission with this drug, but it can also be quite effective, again, at controlling counts. Lastly, there’s ruxolitinib that’s approved currently for patients who have polycythemia and who’ve already had hydroxyurea, and in prospective randomized trials it was shown to control the blood counts quite well. In addition, it’s pretty darn good at controlling spleen size and cytokine-related symptoms, similar to what it does in myelofibrosis. So I think they’re all excellent therapies and have unique roles within the treatment of patients with polycythemia vera. They’re not perfect by any stretch of the imagination, so that’s why we’re always looking to develop new therapies for these patients.

Transcript edited for clarity.