Polycythemia vera (PV) is a type of blood cancer that causes your bone marrow to make too many red blood cells, which causes your blood to be too thick. Symptoms of PV usually develop slowly over many years and are usually nonspecific symptoms like headache, tiredness, sweating a lot (especially at night), itchy skin, stomach issues, and an enlarged spleen. Some of the more serious symptoms that can happen in people with PV include an increased risk of blood clots, including strokes (caused by a blood clot in your brain) and heart attacks (caused by a blood clot in your heart). Besremi (ropeginterferon alfa-2b) is a medicine that was approved by the FDA in 2021. It is a type of interferon that is injected under the skin (subcutaneously) once every two or four weeks to treat PV in adults.
How Does Besremi Work?
The main component of Besremi, interferon alfa, is a type of medicine that works by affecting the bone marrow, where blood cells are made. It attaches to “docking sites” (receptors) called interferon alfa (IFNAR) receptors on cells in the bone marrow and sends signals that slow down the body’s extra blood cell production. Researchers do not know exactly how Besremi works in people with PV, but it helps to keep the blood cell counts closer to normal.
How Do I Use Besremi?
Besremi is given as an injection under the skin (subcutaneous) by a health care provider every two weeks at first. Your health care provider might also decide that you or a caregiver can give the dose after proper training. Your dose will be adjusted based on your blood counts after you get a dose.
If you are taking hydroxyurea (another medicine for PV) when you start Besremi, you will start Besremi at a lower dose. Your dose of hydroxyurea will slowly be decreased while the dose of Besremi is slowly increased based on your blood counts. Eventually, you will stop taking hydroxyurea and only use Besremi.
If your blood counts continue to look good after one year of treatment with Besremi, your health care provider may adjust your dose to be given once a month.
What Monitoring Is Needed During Treatment?
Your health care provider will monitor your labs regularly during treatment to make sure it is effective and safe.
You will have a complete blood count (CBC) drawn every two weeks at first until your blood levels are consistently improved.
Your health care provider will monitor your blood counts and ask about other symptoms, and they may adjust or discontinue your dose for any of the following reasons:
- High liver enzymes
- Low blood cell counts (including red blood cells, white blood cells, or platelets)
- Symptoms of depression or suicidal thoughts
How Was Besremi Studied for Treatment of PV?
Besremi has been studied for treatment of PV in two clinical studies called PEGINVERA and PROUD-PV. Both studies were designed to test the safety and effectiveness of Besremi in adults with PV. To be included, people also had to have a genetic mutation called a JAK2 mutation. JAK2 mutations are common in people with PV (occurring in 90% of people with the disease) and can be used to confirm the diagnosis.
How were the studies designed?
PEGINVERA
The PEGINVERA study included 51 people who were treated with Besremi injections under the skin every two weeks. In the first part of the PEGINVERA study, different doses of Besremi were given to 25 people with PV to determine which dose was the most effective without too many side effects. In the second part of the PEGINVERA study, 26 new people with PV were given the dose that was found to be “best” from the first part of the study. Later, they were tested to see how well the treatment worked to control the blood counts and return the spleen to a normal size (called complete hematologic response).
PROUD-PV
In the PROUD-PV study, 254 people were split up into two groups and given either Besremi, injected under the skin every two weeks, or another medicine that is used to treat PV called hydroxyurea. Hydroxyurea was given as a tablet that was taken by mouth every day. The main goal of the study was to see how well treatment controlled the disease after 12 months. Success was defined by meeting two things at the same time.
- Blood counts were well controlled.
- The spleen was a normal size.
After a year, people in the PROUD-PV study could enroll in an extension study called CONTINUATION-PV to continue receiving treatment for their PV.
What was the study population?
PEGINVERA
- Average age of 56
- 61% were male
- 16% were recently diagnosed with PV
- The rest of the people in the study had known their diagnosis for a median of 2.2 years (meaning half of the people were diagnosed less than 2.2 years prior and half more than 2.2 years prior)
- One-third of people were taking hydroxyurea when the study started
- 22% of people had a prior blood clot-related event
PROUD-PV
- Median age of 60
- 54% were female
- The median time that people had PV was between 1.9 to 3.6 months
- About one-third had taken hydroxyurea before the study started
- About 20% of people had a prior blood clot-related event
What Benefits Were Seen With Besremi in the Studies?
PEGINVERA
At the end of the study, 61% of people treated with Besremi had improvements in their blood counts and a normal spleen size. These effects lasted for a median of 14.3 months. When looking only at improvement of blood counts, 80% of people treated with Besremi saw improvements. The improvement in blood counts lasted for a median of 20.8 months.
Your results may differ from what was seen in clinical studies.
PROUD-PV
After a year, 21% of people treated with Besremi and 28% of people treated with hydroxyurea experienced treatment success (improvements in both the blood counts and spleen size). Improvements in blood counts were similar in both groups (43% with Besremi and 46% with hydroxyurea).
Your results may differ from what was seen in clinical studies.
What Is Known About the Longer-Term Effectiveness of Besremi?
One hundred seventy-one people from the PROUD-PV study enrolled in the CONTINUATION-PV study and continued treatment after the PROUD-PV study ended. CONTINUATION-PV tested the long-term effectiveness of Besremi by looking at the complete hematological response (improvements in blood counts and normal spleen size) with improvements in symptoms of PV. At three years, 53% of people treated with Besremi had a complete hematological response with improvements in symptoms of PV, compared to 38% of people who were treated with hydroxyurea.
What Types of Drug Interactions Can Happen?
Besremi interacts with many other medicines. Some examples are described below.
CYP450 substrates. Medicines like Besremi can interfere with one of the proteins that help break down other medicines before they leave your body, called CYP450. CYP450 substrates are medicines that rely on the CYP450 proteins to be broken down and cleared from your body. Some medicines that are CYP450 substrates can build up in your body if you are also taking Besremi, causing side effects. If you are taking one of these medicines along with Besremi, you may need to be followed more closely by your health care provider or your dose may need to be adjusted.
Other myelosuppressive medicines. Besremi works by lowering the amount of different types of blood cells in your body. This effect is called myelosuppression. If you are taking other medicines that cause myelosuppression, your blood cell levels may drop too low, causing anemia (due to low red blood cells, which help carry oxygen around your body), neutropenia (from low white blood cells, which fight infection), or thrombocytopenia (from low platelets, which help your blood clot).
Medicines that cause dizziness or sleepiness. Besremi can cause you to feel dizzy or sleepy. Feelings of dizziness or sleepiness can get worse if you take Besremi with other medicines that cause the same side effects, such as certain pain medicines, sleep medicines, or other sedatives.
This is not a complete list of medicines that may interact with Besremi. Tell your pharmacist or health care provider about all the prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, or other supplements you take or have recently taken. This will help them determine if there are any interactions with Besremi or if you need a dosage adjustment.
Is There Cost Assistance Available?
The drugmaker offers a patient support program called SOURCE that may help lower your monthly copay to as little as $0. For questions or more information, you can call 800-700-5053.
