Tyruko (natalizumab)

Tyruko (natalizumab) is a disease modifying drug (DMD) for very active relapsing remitting MS.

You take Tyruko as an intravenous infusion (drip) once every four weeks to reduce the number and severity of relapses. It reduces the number of relapses by about two thirds (70%).

Common side effects include dizziness, nausea, urticaria (a skin rash) and shivering.

Treatment with Tyruko may increase the risk of progressive multifocal leukoencephalopathy (PML), an uncommon brain infection that can lead to severe disability or even death.

Tyruko is a disease modifying drug (DMD) for very active relapsing remitting MS. You have fewer relapses than you might have had with no treatment and any relapses you do have should be less severe.

Tyruko is a highly effective (category 2.0) DMD, and is a biosimilar alternative to Tysabri. In clinical trials, people taking Tysabri had about 70% fewer relapses than people taking placebo. In clinical trials, MRI scans showed that people taking Tysabri had fewer, smaller or no new areas of active MS (lesions). Tysabri may also slow down the build-up of disability associated with MS.

Studies comparing Tysabri and Tyruko showed that the active substance in Tyruko is highly similar to Tysabri and produces the same effect in the body.

Tyruko can be prescribed if you have very active relapsing remitting MS, which is defined as two or more relapses in one year, with signs of increasing or new lesions between two consecutive MRI scans.

Tyruko has been approved for use in the NHS since 2023. It can only be prescribed by a neurologist.

It is important that you tell your MS team if you have any health problems or are taking other medicines. Your neurologist will need to know if you have previously taken other drugs which suppress the immune system (for example mitoxantrone, azathioprine, cyclophosphamide or methotrexate).

Pregnancy is not recommended during treatment with Tyruko.

If you are trying for a family, your MS nurse or neurologist may recommend remaining on Tyruko until conception, then review whether you should continue treatment during pregnancy based on how active your MS has been and the risk that you might have a significant relapse.

You take Tyruko as an intravenous infusion (a small tube placed in a vein, with the treatment infused via a pump) once every four weeks. This is generally done in a hospital infusion clinic and takes about one hour.

You should not stop Tyruko without discussing your ongoing treatment with your neurologist, as your MS may become more active after stopping Tyruko.

If you have been asked to switch from Tysabri to Tyruko, your MS team should explain what is involved in the change and give you information about Tyruko. You can switch directly from Tysabri to Tyruko if you have had no problems with Tysabri.

Common side effects include dizziness, inflammation of the nose and throat, feeling sick, vomiting, urticaria (a skin rash), shivering and an increased chance of infection. Tyruko may affect liver function but this generally recovers when treatment is stopped.

Treatment with Tyruko may increase the risk of progressive multifocal leukoencephalopathy (PML), an uncommon brain infection that can lead to severe disability or even death. PML is caused by a mutation of the JC virus, a common infection completely unrelated to MS. It is normally kept under control by the immune system, causing no problems. If your immune system is weakened and your body less able to fight an infection, which may occur when taking Tyruko, the JC virus can become active and cause inflammation and damage to the brain.

A blood test can detect the JC virus and give an indication of the risk that you might develop PML. Other factors which increase the risk of PML include previous treatment with an immunosuppressant drug (for example azathioprine, cyclophosphamide, mitoxantrone or methotrexate) and the length of time you have been taking natalizumab (including both Tyruko and Tysabri). Your neurologist or MS nurse will discuss the implications of the blood test and how it may affect the benefits and risks of treatment.

When you start taking Tyruko you will be informed of the early signs and symptoms of PML. These can be similar to an MS relapse, so it is important to report any new or worsening symptoms. If PML is suspected at any point during treatment, the drug will be discontinued immediately.

Due to the potential risk of side effects, you should be given a patient alert card when you start Tyruko, containing important safety information needed before and during treatment.

• urinary tract infections
• inflammation of the nose
• shivering
• itchy rash (urticaria)
• headache
• dizziness
• nausea, vomiting
• joint pain
• fever

• severe allergic reaction during infusion (rash, swelling of face, lips or tongue, difficulty breathing)
• discomfort during the infusion including feeling sick, headache, dizziness
• progressive multifocal leukoencephalopathy (PML)
• serious infections
• liver problems

A full list of side effects is included in the manufacturer's Patient Information Leaflet.

Blood tests will be performed before starting treatment to determine whether you have been previously infected by the JC virus. You should have blood and urine tests to measure blood cell counts and to check liver and kidney function. It is also important that you have had a recent (usually within 3 months) MRI scan.

Prior to each infusion, blood pressure, temperature and pulse rate will be taken. Monitoring will also take place during the infusion and for one hour after to check for any serious allergic reaction (hypersensitivity).

If a previous blood test found no evidence of a JC virus infection, you should have further blood tests because it is possible to become infected at any time. If a previous blood test found low levels of JC virus infection, you should continue to have blood tests as the virus level may increase. It is recommended that blood tests are repeated every six months.

If you are at high risk of developing PML, your MS team should consider 3-6 monthly MRI scans as detecting PML early will reduce the likelihood of serious disability.

Further advice has been published for health professionals concerning  on how to monitor safety in Tyruko.

The active ingredient in Tyruko is natalizumab. Natalizumab binds to immune cells in the blood stream, preventing them from passing from the blood into the central nervous system where they can damage nerves.

• MS Decisions - a guide to the disease modifying drugs
• European Medicines Agency information on Tyruko
• MHRA Public Assessment Report on Tyruko - Government document explaining how Tyruko was assessed for use in the UK