Elranatamab (Elrexfio®)

You have elranatamab as an injection under the skin (subcutaneous injection) of your tummy or thigh.

During a course of treatment, you will meet someone from your cancer team, such as a:

• cancer doctor
• specialist nurse
• specialist pharmacist.

This is who we mean when we mention doctor, nurse or pharmacist in this information.

During your course of treatment, you will have regular blood tests. This is to check that it is safe for you to have treatment.

You will meet with a doctor, nurse or pharmacist before you have treatment. They will talk to you about your blood results and ask how you have been feeling. If your blood results are okay, the pharmacy team will prepare your injection.

Elranatamab can cause a side effect called cytokine release syndrome or CRS. It can also affect the brain and nervous system, causing a side effect known as ICANS. There is more information about CRS and ICANS in our section about common side effects.

To reduce the risk of these side effects, you start on a low dose of elranatamab. You also have extra medicines 1 hour before your first 3 injections. These help prevent or reduce any reaction.

On day 1, you have your first injection with a low dose of elranatamab.

On day 4, you have a higher dose elranatamab injection.

On day 8, you have a full dose injection.

You then continue to have elranatamab once a week. After 24 weeks of treatment, you have it once every 2 weeks.

Your first 3 injections are usually given during a stay in hospital. This means your cancer team can monitor you closely for any side effects and treat them quickly.  After your first treatments, you may be able to have elranatamab in a day unit or clinic as an outpatient. Your cancer team will explain what to expect.

You usually have elranatamab for as long as it is effective and side effects are manageable. Your cancer team will discuss your treatment plan with you.

Your cancer team may also give you anti-sickness drugs and other medicines to take home. Take all your capsules or tablets exactly as they tell you to.

This treatment makes the body release large amounts of cytokines. Cytokines are chemical messengers that help your immune system protect the body from infection and illness.

You may have flu-like symptoms. These can range from mild to severe. You may need treatment and close monitoring until the symptoms improve. Some people will be monitored and treated in an intensive care unit.

CRS usually happens within 2 days of a treatment. It is most likely to happen after your first, second or third injection. But it can happen later. If you have any of the following symptoms at any time during this treatment, contact the hospital straight away on the 24-hour number:

• a high temperature
• chills
• a fast heart rate
• dizziness or light-headedness
• muscle or joint pain
• diarrhoea
• feeling sick or being sick (vomiting)
• difficulty breathing or shortness of breath.

This treatment can cause temporary effects on the brain. This is called neurotoxicity or immune effector cell-associated neurotoxicity syndrome (ICANS).

Side effects usually happen within 3 days of a treatment. They are most likely to happen after your first, second or third injection. But they can happen later. You may need treatment and close monitoring until the symptoms improve.  Some people will be monitored and treated in an intensive care unit.

You must not drive or use heavy machinery:

• for at least 48 hours after each of the first 3 injections
• or if you have any of the symptoms below.

If you have any of the following symptoms after you go home, contact the hospital straight away on the 24-hour number:

• difficulty speaking
• difficulty writing or doing fiddly tasks, such as fastening buttons or tying shoelaces
• drowsiness
• confusion or disorientation
• reduced consciousness (being less alert)
• memory loss
• tremors or shaking
• muscle weakness
• loss of balance
• headaches
• seizures (fits).

This treatment can reduce the number of white blood cells and antibodies in your blood. White blood cells and antibodies fight infection. If they are low, you may be more likely to get an infection. A low white blood cell count is called neutropenia.

An infection can be very serious when the number of white blood cells is low. Your doctor may give you antibiotics and other drugs to take during this treatment. They may give you an injection or drip to help increase low antibody levels. These treatments may help reduce your risk of getting an infection.

It is still important to get any infection treated as soon as possible. If you have any of the following symptoms, contact the hospital straight away on the 24-hour number:

• a temperature above 37.5°C
• a temperature below 36°C
• you feel unwell, even with a normal temperature
• you have symptoms of an infection.

Symptoms of an infection include:

• feeling shivery and shaking
• a sore throat
• a cough
• breathlessness
• diarrhoea
• needing to pass urine (pee) often, or discomfort when you pass urine.

It is important to follow any specific advice your cancer treatment team gives you.

Your white blood cell count will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time, until your cell count increases.

This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may feel:

• very low in energy
• breathless 
• dizzy and light-headed. 

If you have these symptoms, contact the hospital straight away on the 24-hour number. You may need treatment for anaemia. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.

If the number of platelets is low, you may bruise or bleed easily. You may have:

• nosebleeds
• bleeding gums
• heavy periods
• blood in your urine (pee) or stools (poo)
• tiny red, brown or purple spots that may look like a rash – these spots can be harder to see if you have black or brown skin. 

If you have any unexplained bruising or bleeding, contact the hospital straight away on the 24-hour number. You may need a drip to give you extra platelets. This is called a platelet transfusion.

Feeling tired is a common side effect of this treatment. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can help you feel less tired.

If you feel sleepy, do not drive or use machinery.

The skin in the area that was injected may become:

• painful
• itchy
• red, if you have white skin
• darker, if you have black or brown skin.

Having the injection in a different place each time can help with this.

This treatment can affect your appetite. Don’t worry if you do not eat much for 1 or 2 days. But if your appetite does not come back after a few days, or if you are losing weight, tell your doctor, nurse or pharmacist. They can give you advice. They may give you food or drink supplements. Or they may suggest changes to your diet or eating habits to help.

This treatment can affect your skin. It might feel dry. You may develop a rash, which may be itchy. Always tell your doctor, nurse or pharmacist about any skin changes. They can give you advice or prescribe creams or medicines to help.

If your skin feels dry, try using soap-free cleansers and unperfumed moisturising cream every day.

This treatment may affect the nerves in your fingers and toes. This can cause numbness, tingling or pain in your hands or feet. This is called peripheral neuropathy. You might find it hard to do fiddly tasks such as fastening buttons or tying shoelaces.

If you have these symptoms, always tell your doctor, nurse or pharmacist. They sometimes need to change the drug or the dose of the drug. The symptoms usually improve slowly after treatment ends. But for some people they continue and are a long-term side effect of treatment.