FDA Approves Besremi — A New Treatment Option for Polycythemia Vera

In November 2021, the FDA approved Besremi (ropeginterferon alfa-2b-njft), a twice-monthly

injection for polycythemia vera (PV). This is a rare blood disorder that causes your bones to make too many red blood cells. 

Besremi is a unique medication. It’s the first PV medication available that can be used regardless of previous medications that have been tried. It also has orphan drug (OD) status for PV treatment in the U.S. 

And although it’s new to the U.S., it’s not as new in other parts of the world. It was approved for the treatment of PV in the European Union (EU) in 2019, in Switzerland and Taiwan in 2020, and in Israel and South Korea earlier in 2021.

Here, we'll cover what you should know about Besremi for PV — what it is, how it works, and when it'll be available.

What is Besremi?

Besremi is an injectable medication that's administered every 2 weeks. It was FDA-approved in the U.S. in November 2021 to treat adults with PV. Its approval was based on data from a European clinical development program managed by AOP Orphan, a European company that focuses on treating rare diseases. 

Besremi is a long-acting interferon, specifically interferon alfa-2b. The medication is coated with a chemical called polyethylene glycol. This technology — called pegylation — allows for better medication solubility, stability, and makes the medication stay in your blood longer.

How does it work for polycythemia vera?

Red blood cells are very important. They perform tasks like carrying oxygen to tissues and organs throughout your body.

But PV is a blood disease that tells your bones to create too many red blood cells. These extra red blood cells can thicken your blood. This can make it harder for oxygen to travel throughout your body. Without enough oxygen, many parts of your body are affected. Thicker blood can also lead to blood clots, and these can be dangerous.

Besremi works by attaching to receptors (chemical binding sites) on cells in your body called interferon alpha receptors (IFNAR). It’s thought that this causes your body to make fewer blood cells. 

How is it dosed and given?

Besremi is available as a single-dose injection. It comes as a prefilled syringe, and you'll throw away the syringe after each shot.

Besremi is injected under the skin in your lower abdomen or top of the thigh. You'll give yourself the injection once every 2 weeks, on the same day each week. It can be given at any time of the day, and you can take it with or without food. 

The recommended dose depends on whether you've used a medication called hydroxyurea. Hydroxyurea treats several types of blood disorders. 

If you haven’t already taken hydroxyurea, you’ll likely inject 100 mcg of Besremi under the skin every 2 weeks. You’ll then raise your dose by 50 mcg every 2 weeks until your target dose is reached.

But if you’re in the process of stopping hydroxyurea, you start with half of that dose — 50 mcg instead of 100 mcg. You’ll likely raise your Besremi dose every 2 weeks until your target dose is reached. At the same time, you’ll gradually stop taking hydroxyurea over about 12 weeks (3 months).

Your healthcare provider may want you to stick to a 2-week dosing interval for a while. But if your blood counts are looking good for at least 1 year, then you may only have to give the shot once every 4 weeks. 

Is Besremi safe and effective?

Besremi’s safety and effectiveness information is based on data from the PEGINVERA study.

In this small study, 51 adults with PV received Besremi for about 5 years. Effectiveness was assessed by looking at how many people achieved a complete blood response. A complete blood response includes having an ideal level of red blood cells, white blood cells, and platelets.

Ultimately, the study showed that over 60% of people with PV had a complete hematological response. 

What do we know about potential side effects?

Like all medications, side effects may occur after receiving Besremi. The most common side effects reported in more than 40% of people in the PEGINVERA study were:

• Flu-like illness

• Joint pain

• Tiredness

• Itching

• Muscle pain

But in some cases, Besremi may cause more serious side effects. The medication has a boxed warning — the FDA's most serious warning — regarding a potential risk or worsening of the following:

• Neuropsychiatric disease (e.g., bipolar disorder, schizophrenia, or ADHD)

• Autoimmune disorders (the immune system reacts against normal healthy parts of the body)

• Health conditions that impact blood flow in your body

• Infectious diseases

Because of this, you shouldn't take Besremi if you live with any of the following:

• Personal history of severe psychiatric disorder

• Liver disease

• Have or had an autoimmune disorder

• Received an organ transplant in the past

There have also been rare reports of serious side effects like heart, kidney, and lung problems. For more information, speak to your healthcare provider. 

Can it interact with other medications?

Yes, Besremi can interact with several medications. Besremi can interact with:

• Medications that are heavily metabolized by certain liver enzymes, like amiodarone, tacrolimus, or warfarin

• Medications that impact your blood cells, like chemotherapy, sulfasalazine, or azathioprine

• Sedative or hypnotic medications, like benzodiazepines or barbiturates

• Narcotic pain medications, like morphine or oxycodone

It is important your provider and pharmacist have a complete list of all the medications and supplements you take. They can make sure it is safe for you to take Besremi. 

How does Besremi compare to other polycythemia vera treatments?

PV doesn't have a cure. However, some other treatments help keep your bone marrow from making too many red blood cells which control PV and its complications. Examples of these treatments include: 

• Low-dose aspirin

• Phlebotomy (a procedure that removes blood from your body)

• Other medications to reduce the number of red blood cells (e.g., hydroxyurea, ruxolitinib)

Both Besremi and hydroxyurea aim to lower the number of red blood cells in your body. Two studies showed that people taking Besremi continued to get better over 36 months (3 years) compared to people who took hydroxyurea.

But, importantly, there isn’t one best PV medication or treatment. Treatment decisions should be based on your specific risk factors, such as your own risk for clotting. If you have PV, you should chat with your healthcare provider to discuss the next steps in your care.

When will it be available?

PharmaEssentia, the medication’s manufacturer, is reportedly preparing to make Besremi available in the coming weeks in the U.S. But since it was recently approved in the U.S., it may not be available right away. 

When it is available, it’ll likely only be available through a specialty pharmacy. Specialty pharmacies can help you obtain medications used to treat chronic or rare medical conditions like PV. If your healthcare provider decides to start you on Besremi, contact the specialty pharmacy ahead of time to see if they have your medication in stock. 

How much will it cost?

Although Besremi's list price isn't currently available, PharmaEssentia Source offers financial assistance options for Besremi. It's important to note that if you have insurance that covers this medication, it's unlikely that you'll end up paying the list price. In this case, you'll likely end up paying a copay based on your specific coverage. 

Plus, you may qualify for a $0 manufacturer copay card to make the medication more affordable if you live in the U.S. and have commercial insurance. PharmEssentia also offers Besremi at no cost to people who qualify, including those without insurance, through a patient assistance program.

Once the medication is available to the public, we'll have more information about costs, coverage, and ways to save.

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Written by:

Nikki Javit, PharmD

Nikki Javit, PharmD, is a clinical pharmacist with certifications in international travel medicine, immunization delivery, and pharmacogenomics. She received her bachelor’s of science in biology from Indiana University Bloomington and her doctor of pharmacy degree from Butler University.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

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