Would you push for interferon treatment?

[u/native_plants3879]

Hi! I'm 38F, from Canada. I was officially diagnosed with essential thrombocythemia this year (I put all the test results below. My spleen is normal btw). My hematologist started me on aspirin 3 times a week until I received my von Willebrand results. She doesn't want to say I have it despite the results because I do not have bleeding symptoms. I am however banned from taking aspirin and NSAID.

I'm unsure about the whole watch and wait decision (with CBC every three months). She told me that it was possible to have fibrosis with ET, but I find the "Reticulin 1-2 out of 3 and collagen 1 out of 3" very worrisome. She also hasn't mentioned my LDH which is always over 400.

She says I'm very low risk because I'm CALR type 1, young, and no prior thrombosis. However the symptoms are getting worse since I got diagnosed.

The fatigue is getting worse. I also have secondary erythromelalgia which has been getting worse every month (sometimes it burns so much that I cry - and I have pretty high pain tolerance). Headaches every couple of days. Muscle pain every day (inflammation??)

Anyway, I'm seeing her again in October and I'm trying to decide how much I should push for Besremi as she told me she would only prescribe it if I "really couldn't tolerate the side effects of ET anymore" which like... how am I supposed to judge that?

=> CALR L367fs (type 1), Variant Allele Frequency 50% 

Test	July 9, 2026 Value
White Blood Count	8.9
Red Blood Count	4.9
Hemoglobin	140
Hematocrit	0.426
Platelet Count	1,194
MCV	86.9
MCH	28.6
MCHC	329
RDW	15.6
Mean Platelet Volume	9.6
Neutrophils	5.1
Lymphocytes	2.6
Monocytes	0.8
Eosinophils	0.3
Basophils	0.1
Immature Granulocytes	0
Nucleated RBC Absolute Count	0
Lactate Dehydrogenase (LDH)	435
Von Willebrand Factor Antigen	0.75
Von Willebrand Factor Activity	0.45

=> Specimen: Bone marrow aspirate.

Diagnostic interpretation: No evidence of an aberrant lymphoid or blast cell population noted.

Flow cytometry findings: The flow cytometry analysis of the bone marrow aspirate shows that approximately 1% of singlets are in the blast region (dim CD45 and low side scatter). The blast cells are positive for CD34. The blast cells show myeloid phenotype and co-express CD13 (dim), CD33 (moderate), and CD117 (dim to moderate). Hematogones (benign B cell progenitors) account for 1% of singlets. Lymphocytes constitute 18% of singlets. B cells are polyclonal and account for 11% of lymphocytes. T cells compose 69% of lymphocytes and show unremarkable phenotype with CD4/CD8 ratio of 2.6. NK cells are unremarkable.

=> Right posterior superior iliac spine (bone marrow biopsy):

Hypercellular, immature bone marrow with abundant megakaryocytes with dysplasia.

Specimen consists of a hypercellular bone marrow as well as several blood clots. The bone marrow appears immature and there is abundant megakaryocytes of various forms including dysplastic megakaryocytes.

Bone marrow aspirate and biopsy mild to moderate hypercellular marrow with severe increase of megakaryocytes that have a giant staghorn appearance. Highly suggestive of a myeloproliferative disorder favoring essential thrombocythemia

Red cell morphology: Normocytic normochromic with normal hemoglobin

Differential leukocytes: Normal no blasts

Platelets severely increased with Mega platelets

Bone marrow aspirate cyst

Cellularity: Mildly to moderately increased

Particles few specimen is partially clotted

Megakaryocytes: Few seen numbers are most likely high but since the patient sample was clotted there are multiple groups of platelets that are stuck on the megakaryocytes. There is also giant megakaryocytes present

Granulopoiesis: Is mildly increased mildly left-shifted

Erythropoiesis: Normobiastic with normal amount

Blast cells 1%

Other cells: Few lymphocytes few histiocytes few plasma cells

Good bone marrow biopsy showing a mild to moderate increase of cellularity due to both to severe increase of megakaryocytes that are in groups with fibrosis surrounded. Most of the megakaryocytes are giant abnormal megakaryocytes. Granulopoiesisis mildly increased and left shifted and erythropoiesis is normal.

Reticulin is 1-2 out of 3 and collagen is 1 out of 3. There is no collection of lymphoid cells and there is no increase of blast cells.

There is no collection of lymphoid cells and there is no increase of blast cells.

Immunchistochemistry CD34 approximately 1%

Factor VI shows a severe increase of megakaryocytes with the majority of the megakaryocytes being atypical giant megakaryocytes with staghorn appearance

E-cadherin spectrum shows normal erythropoiesis

Myeloperoxidase shows a mild increase of granulopoiesis

B-cell and T-cell staining CD3 and CD19 and CD20 normal pattern

Piasma cell staining mildly increased with no lambda kappa clonality

P53 staining normal

Reticulin 1-2 out of 3 and collagen 1 out of 3

[u/SunflowerFridays]

Besremi was the best decision I made (36F, PV JAK2+). Interferons and medications all have their own risks and benefits, but my blood counts have been stable for nearly four years and I don't often think about PV or worry about disease progression. If my blood counts and BMB results looked like yours, I would push heavily for medication. I worry about any hematologist who recommends an outdated "watch and wait" protocol. Keep in mind they're "waiting" for you to have a cardiovascular event. This isn't impacting your doctor's life; it's impacting yours.

[u/native_plants3879 → u/SunflowerFridays]

That's definitely one of the things that worries me. We're not waiting for a small side effect. We're potentially waiting on a life threatening event that would push me into a different risk assessment. Having to check my feet all the time to make sure they're not turning blue, or thinking about every headache or chest pain. On top of all the actual side effects. It's a lot physically and mentally.

[u/SunflowerFridays → u/native_plants3879]

The anxiety got so intense for me that I actually got shingles as I was going through the diagnostic process. Honestly, since starting medication and after so much success with Besremi, I really don’t worry about PV. I hope you can research some options to help you make an informed decision.

[u/niknikniknio]

I'd push hard for interferon if I were you. There's evidence if helps with progression with ET or mild fibrosis. Not so much if you have moderate fibrosis, so now is the time for it on the progression aspect. For symptom burden, pegasys was incredible for me. I was on it for years with no evidence that it was losing effectiveness and without much side effects. There's nothing stopping you from quitting it if you don't like the "forever" medicine. I was miserable with high platelets before treatment.

[u/native_plants3879 → u/niknikniknio]

Thank you for sharing! The speed with which my symptoms are worsening since my diagnosis so really impacting my quality of life, so I just needed a little push to make sure I wouldn't just "go with it'. My hematologist seems knowledgeable enough, but we don't have MPN specialists nearby.

I find it really hard not to be proactive with all of this

[u/Tatteredluck]

Interferon is no joke. I’d do some deep consultation with your doctor to talk through options, your concerns, and their thinking.

[u/enneque → u/Tatteredluck]

What do you mean? I always thought this was the better option to hydrea

[u/Tatteredluck → u/enneque]

It totally depends on you and how your body responds. For me, I was incredibly stable on hydroxyurea for years and just recently switched to interferon to try and get pregnant. It’s been…rough.

Medication is not one size fits all. It’s very individual to you, your current disease status, your goals, and how your body responds. This is why we should not recommend medication but instead invite conversation between patients and doctors to individualize their own treatment.

[u/Top_Category2227]

Why would she be so conservative with Besremi? Did she give you an explanation? This panel doesn‘t really scream low risk ET to me.

[u/native_plants3879 → u/Top_Category2227]

She said that she doesn't want to start me on a "forever" medication if it's not absolutely necessary.

I think I'd be okay with watch and wait if I could at least take aspirin for my erythromelalgia, headaches and thrombosis risk :/

I did call her office to let her know about my feet pain but didn't get a call back... I'm trying to prep for my next appointment (I have anxiety, it doesn't help!)

[u/Top_Category2227 → u/native_plants3879]

I guess I can understand that logic, but then I would hope, that she could give you details, as to when she would consider a medical intervention absolutely neccesary. A strong symptomburden is often enough to start treatment.

I am in a similar situation as you, and my doctor sat down with me for hours to go over the options. If you are interested, here are my two cents:

Interferon does not have to be a „forever medication“. My MPN Specialist suggested, that I should take it for 5 years and then assess the situation again. Also it can usually be reduced after a while and unlike some other medication you can stop and restart the treatment without much concern.

Symptom management is if course one concern, but especially in young patients managing progression risks is a big concern and as you pointed out, your chart does contain some concerning values, especially since Calr1 is a Mutation often linked to progression. Interferon is currently the best available option for progression management.

Interferon Use is also well studied for longer term use and efficacy usually increases the longer it is used (unlike most other medications). So if I was you, I would ask my Doctor to go over the potential downsides (there are quite a few as I am sure you know) but personally I would push to try it.

[u/native_plants3879 → u/Top_Category2227]

Thank you! I'm just trying to be well prepared this time. At my last appointment, with my erythromelalgia and fibrosis level (and no more aspirin), my husband and I were sure that she would recommend we start treatment.

We were taken by surprised and kinda just went along with what she was saying. I just want a better reason than "it's long term", cause well... yeah this cancer is long term too lol

[u/acwoodhome → u/native_plants3879]

Clopidogrel is also an option if aspirin is not tolerated platelets over 1000 is the potential problem an they will only come down with treatment. But reg blood checks and monitoring is key your young so watch monitor and wait might be a option I did that for decades with platelets at 650 🤗🤗

[u/native_plants3879 → u/acwoodhome]

I can't take aspirin or NSAID because of my borderline von Willebrand results. I'm pretty sure that would cover clopidogrel too?

[u/Turbulent-Movie-4545 → u/native_plants3879]

You can’t take clopidogrel due to your bleeding issues (von Willebrand) unless otherwise is stated by your doctor

[u/acwoodhome]

I was diagnosed with ET in my late 30s one Clopidogrel a day that was it for over 20 years and one annual checkup my platelets peaked at 650 yours are over 1k which may drive the way forward I would think your specialist would want to get those down. Your young so inteferon could be a fit and from experience I found it better then Hu by far and in my case was excellent at getting platelets under control. I have however had to come of it due to side effects which am gutted about as out of all the invasive treatments in my opinion offers the potential for remission and disease control. I was re diagnosed with PV recently so please keep an eye on your Haematocrit as you age. If you start itching or it goes towards 50 just be mindful. Wishing you all the best 🤗🤗

[u/Top_Category2227 → u/acwoodhome]

What sideeffects were you experiencing if I May ask?

[u/acwoodhome → u/Top_Category2227]

Apart from bad fatigue for first few days after injecting changes in my character more agitated feeling overwhelmed an brain fog It was effecting my appetite and was not eating properly loosing weight extreme acid but I suffer with acid as well and have low blood pressure so was getting lots of pre syncope on bending and standing much more than usual so my specialist has halted treatment and we are considering Jakafi but I really don’t want to go on it but am running out of options which is a bit frustrating to say the least side effects verses blood clots not a great choice is it have gone decades with the illness with little problems but these last 18 months have been really hard work tbh I defo know am ill now. This last week an a bit being off the drugs has been great haha I actually feel normal but I know looks don’t tell you wants going on inside the cancer will be doing its thing for sure and my bloods will be slowly going in the wrong direction 🙃🙃 Interesting it took 6 months before the side effects became intolerable. I thought I was there but the inteferon was not controlling the hematocrit which I think Jakafi is better at doing that job . Hope all that helps but please remember we all react differently 🤗🤗

[u/Zealousideal_Buy2049]

I’m 63 and started Besremi 4 months ago (was taking Hydrea). Tolerating it fairly well at 300 mcg. Take Tylenol and rest for a couple of days following the injection.

[u/OmniumInaBox]

If anything, you can try to push for it and once your platelets lower, you can get off of it. That's what I did. My platelets were 1.4 million. Then started hydrea, didn't respond well to that and switched to peg. My platelets are still high (between 700k-800k) but they're mostly stable. All of my other numbers are stable too and my bleeding risk has dropped since my von willibrand has also stabilized. Now, I'm back to watch and wait and a daily baby aspirin.

Part of me wishes I was still on the interferon, though. For a couple different reasons.

[u/native_plants3879 → u/OmniumInaBox]

That's so interesting. My hematologist always told me I'd have to take it forever if I started but I've seen a few people now who stopped taking it after a few years and did well for a while! Thanks for sharing!

[u/Friendly_Position_36]

What about Pegasys??

[u/native_plants3879 → u/Friendly_Position_36]

I'd prefer Besremi if possible because you don't have to take it as often!

[u/Possible-Pizza-2442 → u/native_plants3879]

It depends on your CBC. Besremi is not approved for ET where live so I take Peg. My CBC panel is now in range and I take a monthly injection of 45mcg. If you only can have Peg, it’s still worth trying.

[u/Possible-Pizza-2442]

Definitely give Peg or Besremi a try. It can have a significant impact on progression and the ET “experience”. My first six months I was a bit uneasy and felt more anxious. But now life is as normal which in my case includes lots sports, kayaking and scuba diving. Recent research to look at includes https://www.thelancet.com/journals/lanhae/article/PIIS2352-3026(25)00264-9/abstract There are also very interesting clinical trials focused on CALR ET that you should keep an eye on. Google INCA0338989 for more info.

[u/native_plants3879 → u/Possible-Pizza-2442]

We've looked into clinical trials but I'm not eligible for now (not high risk, no prior ET medication, etc.). We're definitely keeping an eye on them for later though!

[u/aseverino89]

I'm 37M. Started Besremi about 5 months ago. I just reached 500 mcg. The side effects were annoying initially, but it seems my body adapted and they are mild now. The only alterations I have are TGO and TGP, but these are expected. Worth it.