How important is molecular response (allele burden) for PV treatment?

Nothing helpful to say; but following along, as I have PV and am told I am at higher risk for myelofibrosis. Currently taking HU, but understand Besremi will be better for addressing that allele load at the source, and hope to discuss with my dr soon.

When I get my Jak2 test in December, if the allele burden doesn't get much better, I will seek to ask my hematologist to proceed with one of the options. I am retiring at the end of the year, so it will be easier to manage a little extra fatigue.

I have been slowly removing HU and starting with Besremi 50 mcg every two weeks. All my labs were great except platelets which were 520. I am on my third injection so I will go to 100 mcg and drop the HU entirely. This will be interesting. My JAK 2 had gone from 15 to 68% over 6 yrs.

Has anyone been told they are too old to start Besremi because it takes too long to make a difference? I am a very active and healthy 78 and in spite of my doctor trying to get me to stay on HU and phlebs and doing great, I’m going for Besremi.

Hi @mcsulli This will be interesting to follow your case along with your switching to Besremi from HU. According to the Besremi website, 27% of patients saw comprehensive disease control in 10 weeks! That’s remarkable.
Here’s the informational article from Besremi. https://besremi.com/pv/wp-content/uploads/sites/2/2026/07/BESREMi-what-to-expect-guide.pdf

Have you been doing well with the injections?

I have only had two and it went ok with no real identifiable side effects. Tomorrow is my third and increasing to 100 and I believe I am to go off HU entirely and try it for two weeks. I have not gotten a response from the doctor as to any more Hu or not. Hopefully they will let me know because another option he had suggested Hu every three days before I go totally off. I’m expecting some kind of reaction with twice the dose of Besremi but we shall see.

Studies have shown that Besremi tends to lower the risk of progression to myelofibrosis. HU doesn't do anything to lower Jak2 or inhibit progression.
The longer you are on HU, the more likely you are to experience painful side effects like sores and ulcers. I think anyone with pv or et who has an opportunity and does not have any risk factors should consider going on Besremi and get off HU, no matter how old they are. Another option for pv patients is rusfertide, which was approved by the FDA in August. It regulates the iron levels and reduces the need for phlebotomy. It might be safer than HU but is not intended to reduce the allele burden.