What is Ruxolitinib Discontinuation Syndrome?

Ruxolitinib is one of the main medications used to treat myelofibrosis. It helps control symptoms and works to keep the disease stable. However, when a person stops taking this drug, whether due to side effects or because the treatment is no longer working, a sudden reaction can occur. This reaction is known as ruxolitinib discontinuation syndrome (RDS).

Understanding what RDS is, why it happens, and what symptoms to watch for helps patients and caregivers navigate changes in treatment safely alongside their care team.

What causes ruxolitinib discontinuation syndrome?

Myelofibrosis is a rare type of blood cancer. Scar tissue builds up in the bone marrow. This makes it difficult for healthy blood cells to form. Ruxolitinib treats myelofibrosis by blocking certain signals in the body that cause inflammation and bone marrow issues. While taking the medication, levels of inflammatory proteins are kept low.

When the medication is stopped suddenly, those inflammatory proteins can quickly flood back into the body. This sudden spike, sometimes called a "cytokine storm," triggers a rapid return or worsening of disease symptoms. RDS typically appears within three weeks after stopping the medication.

People who have a larger spleen or low blood platelet counts when stopping the drug are at a higher risk of experiencing this syndrome.

What are symptoms of ruxolitinib discontinuation syndrome?

Symptoms of RDS can range from mild discomfort to severe medical issues. They depend on how intensely the body reacts after the medication is stopped.

Mild to moderate symptoms 

Most cases of RDS are mild or moderate. Common warning signs include:

• Rapid swelling, discomfort, or pain in the spleen (upper left side of the belly)

• A sudden flare-up of general symptoms like fever, night sweats, or unexpected weight loss

• Increased tiredness, itching, bone pain, or stomach discomfort

Severe symptoms 

In rare cases, RDS can cause life-threatening complications that require urgent emergency medical care. These can include:

• Severe breathing problems or sudden lung trouble

• Confusion

• Extreme dizziness

• High fever

• Serious complications with the spleen

How is RDS managed and treated? 

Because stopping ruxolitinib carries risks, doctors carefully plan and monitor any changes to this medication:

• Gradually lowering medication dose: Instead of stopping the medicine all at once, care teams often slowly lower the daily dose over several days or weeks to help prevent a sudden surge of inflammation.

• Anti-inflammatory medications: Doctors may temporarily prescribe anti-inflammatory medications, such as steroids, to keep symptoms under control while weaning off the drug.

• Restarting therapy: If severe symptoms occur after stopping, restarting ruxolitinib can rapidly calm the reaction and help stabilize the body.

• New therapy: Care teams aim to start any new planned treatments as soon as possible after stopping ruxolitinib to keep disease symptoms managed.

Never reduce your dose or stop taking ruxolitinib on your own. By knowing the signs of ruxolitinib discontinuation syndrome and reporting any new or worsening symptoms right away, patients and caregivers can ensure that care transitions remain safe and comfortable. 

Sources: 

• Ruxolitinib discontinuation syndrome: incidence, risk factors, and management in 251 patients with myelofibrosis

• Ruxolitinib Discontinuation Syndrome in a Patient with Primary Myelofibrosis