by David Wallace
The Big Picture
If you’ve been diagnosed with a myeloproliferative neoplasm (MPN) such as polycythemia vera, essential thrombocythemia, or myelofibrosis, you’ve likely heard about interferon therapy.
Keep reading to discover what current research tells us about this treatment option.
What Exactly Is Interferon?
Think of interferon as your body’s natural antiviral security system. Scientists discovered interferons back in 1957 when they noticed that cells infected with viruses released special proteins that helped fight off the infection. In scientific terms, interferons are signaling proteins in the immune system that help fight infections and cancers by, you guessed it, “interfering” with the multiplication of viruses, as well as by activating immune cells.
Today, we use lab-made versions of these proteins as medicine.
The Modern Advantage: Today’s synthetic interferons undergo pegylation, a modification that extends their lasting power in your body while minimizing side effects. You only need injections every 1 to 2 weeks, instead of multiple times weekly with the older generation interferons.
The Importance of Interferons for MPN Patients
More Than Just Managing Symptoms
Unlike some other MPN treatments, rather than primarily controlling blood counts, interferon appears to actually target the root cause of your disease. Namely, those faulty genes (JAK2, CALR, MPL) that are driving your MPN.
What Differentiates This Treatment Method?
- Blood count control: Returns your red blood cells, platelets, and white blood cells back to normal levels
- Symptom relief: Helps with fatigue, itching, and enlarged spleen
- Clot prevention: Reduces the risk of dangerous blood clots
- Gene targeting: Reduces the percentage of abnormal cells in your body
The “Disease-Modifying” Potential
Here’s the exciting part. Recent studies suggest interferon might slow down, or even halt, the progression of your MPN. Some patients using this method reported such good results, they were able to stop treatment entirely and remain stable, similar to what we observe with certain leukemia treatments.
What Research Shows
For Polycythemia Vera (PV)
The evidence is strongest here. Numerous studies have discovered the following:
- Response rates: 60 to 80% of patients see significant improvement
- Long-term benefits: Patients often do better over time compared to traditional treatments like hydroxyurea
- Genetic improvement: The percentage of abnormal JAK2 genes in blood samples decreases significantly
- Quality of life: Many patients report feeling better and needing fewer blood draws (phlebotomies)
Key finding: Even patients with “low-risk” PV (younger, no previous clots) benefit from taking interferon compared to undergoing regular blood draws.
For Essential Thrombocythemia (ET)
The research is still growing, but early results are promising:
- High response rates: About 80 to 89% of patients respond well
- Low complications: Very few patients experience dangerous clots or bleeding
- Genetic benefits: Similar to PV results, abnormal gene levels decrease over time
For Myelofibrosis (MF)
For now, the evidence is more limited; but interferon might help patients with early-stage myelofibrosis. Advanced myelofibrosis patients typically need different treatments.
Managing Side Effects: It’s Not as Bad as You Think
In the past, interferon lab formulations were known to cause severe flu-like symptoms. Today’s pegylated versions (Besremi and Pegasys) are much more tolerable.
Common Side Effects and Solutions:
- Flu-like symptoms: Fever, fatigue, muscle aches, which typically improve after the first few months
- Blood count changes: In many patients, the effect is seen first in hematocrit/red blood cells (especially in PV) and platelets, notably in ET. All myeloid lines may be suppressed including white blood cells, especially neutrophils, leading to neutropenia in some patients. Your doctor will need to monitor this closely.
- Mood changes: Some patients may experience depression or anxiety
- Fatigue: Often improves as your MPN is better controlled
Making It Easier:
- Start low. Go slow: Your doctor will likely begin with a lower dose and gradually increase it
- Timing matters: Many patients find taking interferon before bedtime mitigates the side effects
- Most side effects are manageable: Only about 13 to 15% of patients stop treatment due to side effects
As with all MPN therapies, serious side effects have been reported and should be discussed with a qualified hematologist before starting treatment.
Special Considerations
If You’re Young
MPNs are not exclusively diseases of the old. In fact, around 20% of diagnoses occur in people under the age of 40. For younger patients, interferon offers some unique advantages:
- Long-term benefits: Potential to prevent disease progression over decades
- Pregnancy safety: It’s the only MPN treatment considered safe during pregnancy (see more below)
- Preserving options: Doesn’t limit future treatment choices
Planning for Pregnancy
If you’re a woman of childbearing age, interferon is currently the only safe MPN treatment during pregnancy. Other common treatments like hydroxyurea and JAK inhibitors are not recommended for pregnant women. Learn more about managing MPNs during pregnancy.
The Bottom Line
Interferon treatment for MPN patients has been successfully prescribed for over 35 years. What’s more, today’s versions are safer and more convenient than ever. While newer treatments like JAK inhibitors have received a lot of attention, interferon remains a powerful option, especially for the following populations:
- Younger patients who seek to slow disease progression
- Women planning pregnancies
- Patients seeking genetic-level improvement (not just symptom control)
- Those who haven’t responded well to other treatments
Questions to Ask Your Doctor
- Based on my specific MPN type and risk factors, could interferon be right for me?
- How would you monitor my response to treatment?
- What’s your experience with managing interferon side effects?
- How long might I need to stay on treatment?
- Could I eventually stop treatment if I respond really well?
Looking Ahead
Research continues into interferon’s potential for achieving treatment-free remission, where patients can stop therapy entirely while maintaining their improved condition. While we’re not there yet, the early signs are encouraging.
Remember: Every MPN patient is unique. What works best for you depends on your specific diagnosis, age, symptoms, and personal goals. This information is intended to supplement, not replace, discussions with your healthcare provider or team.
Author’s Personal Note
I’ve been in complete molecular and hematological remission from PV for 6 years, and my healthcare team offered me the option to stop using Pegasys.
According to my research, most evidence favors continuing interferon (Pegasys or Besremi/ropeginterferon) at the lowest effective maintenance dose rather than stopping treatment at the first complete hematologic response (CHR). Some patients who also achieve deep, sustained molecular responses (very low JAK2 V617F allele burden) have stayed in remission off therapy, but this is not yet standard practice.
I chose to stay on a monthly maintenance dose and have been very pleased with the results.
Reference
Daunov, M., & Klisovic, R. B. (2025). Pegylated Interferons: Still a Major Player for the Treatment of Myeloproliferative Neoplasms. American Society of Clinical Oncology Educational Book, 45(3), e473912. https://doi.org/10.1200/EDBK-25-473912
This article is based on recent research published in the American Society of Clinical Oncology Educational Book. Always consult your healthcare provider before making treatment decisions.
