Ofatumumab (Kesimpta)

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• Who can take ofatumumab (Kesimpta)?
• How do you take ofatumumab (Kesimpta)?
• How does ofatumumab (Kesimpta) work?
• How well does ofatumumab (Kesimpta) work?
• Ofatumumab (Kesimpta) side effects
• What tests do you need with ofatumumab(Kesimpta)?
• Stopping ofatumumab (Kesipmta)
• Ofatumumab (Kesimpta) and pregnancy, breastfeeding and contraception

Who can take ofatumumab (Kesimpta)?

Across the UK you can have ofatumumab (Kesimpta) if:

• you have ‘active’ relapsing MS. That means you’ve had a recent relapse and/or MRI scans show that you have new, active or growing lesions

You might be offered ofatumumab as your first DMT. Or you might switch to it if you’re taking a DMT that’s not controlling your MS well enough.

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How do you take ofatumumab (Kesimpta)?

You take ofatumumab (Kesimpta) by injecting it under the skin in your thigh or belly (not into a vein or muscle). You do this once every month with an injector pen that comes already filled with the drug. You hold the pen against your body and click to release the drug. You don’t see the needle go in. Your MS nurse or a nurse from your MS team will show you how to use the injector pen. After that you inject yourself at home each month.

Treatment begins with starter doses, with one dose a week for three weeks. Then you skip a week before taking your first monthly dose on week five.

If you leave this drug in any kind of light, it won’t work as well, or at all. So keep the pre-filled pen in the box it comes in. Don’t shake it.

You must keep ofatumumab in the fridge (at 2°C to 8°C) or a cooler if you’re travelling. In an emergency, you can keep the pen at room temperature for up to seven days as long as it doesn’t go over 30°C. If it does, don’t use the drug. If you’ve kept the pen at room temperature but not used it by the seventh day, it must go in the fridge (and be used within the next seven days or else thrown away).

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How does ofatumumab (Kesimpta) work?

We don’t fully understand how ofatumumab (Kesimpta) works, but it targets B cells. We think these cells in your immune system cause a lot of the damage in MS.

B cells kill viruses and bacteria, but in MS they also damage nerves. They strip off the covering of myelin around nerves in your brain and spinal cord. Myelin protects nerves from damage and helps messages travel along them. By killing B cells, the drug stops them damaging the nerves’ myelin. You then get relapses much less often.

Ofatumumab (Kesimpta) is a monoclonal antibody drug. These artificial antibodies, made in a laboratory, stick to B cells and kill them. Any MS drug that ends in ‘mab’ is a monoclonal antibody. 

Ofatumumab (Kesimpta) is a new kind of monoclonal antibody called an antiCD20 drug. These drugs stick to the CD20 antigen protein on the surface of B cells. That makes them better at targeting B cells, leaving other immune cells alone. This means fewer serious drug side effects.

Ofatumumab (Kesimpta) reduces how much inflammation doctors can see on your MRI scans. This inflammation shows up as areas of damage to nerves called lesions. 

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How well does ofatumumab (Kesimpta) work?

The effectiveness of ofatumumab (Kesimpta) is classed as 'high'. Each DMT can be rated as ‘moderate’, ‘good’ or ‘high’ based on two things. One is how much it reduces relapses. The other is how much it slows down disability getting worse.

Monoclonal antibody drugs like ofatumumab (Kesimpta) are some of the DMTs with the best results. 

Two trials from 2020 called ASCLEPIOS I and II led to ofatumumab getting the green light for use in the UK by the NHS. These trials compared it to another MS drug called teriflumonide (brand name Aubagio).

Ofatumumab was a lot better than teriflunomide at reducing relapses. It was also better at reducing how many lesions doctors saw on people’s MRI scans.

Relapses dropped by:  

51-59% compared to teriflunomide. 

This means that, over two and a half years, on average people saw a drop of 51% in one trial and 59% in the other trial in the number of relapses they had. This was compared to people who took teriflunomide. 

Disability getting worse was slowed down by: 

around a third compared to teriflunomide.   

This means that in the two trials, on average, people saw a drop of around a third in the risk of their disability getting worse. This was compared to people who took teriflunomide.

A study from 2022 looked at a specific group of people who took part of the ASCLEPIOS I and II trials. These people had never taken a DMT before. Ofatumumab (Kesimpta) worked even better for them. Compared to people on teriflunomide, these people saw their relapses fall by a half. And their risk of disability getting worse fell by almost a half (46%).

How well does ofatumumab (Kesimpta) work over many years?

Studies have now followed people on ofatumumab (Kesimpta) for over quite a number of years. There have been no new side effects that doctors didn’t already know about. And the good results from the early trials have lasted. In two trials after four and five years at least eight in ten people on ofatumumab had no signs that their MS was still active. This means they had no relapses or new, active or growing lesions. The risk of their disability getting worse stayed low.  

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Ofatumumab (Kesimpta) side effects

Very common side effects (more than 1 in 10 people get them):

Infections:

• colds
• chest infections
• bladder infections
• other urinary tract infections

You’re more open to infections because ofatumumab lowers your levels of B cells. And B cells make immunoglobulin, an antibody that fights infections.

Injection reactions (up to one in five people get one or more these). These can be:

• headache
• muscle aches and pains
• chills
• feeling sick
• fever
• tiredness
• hives (a painful skin rash)
• trouble breathing
• swelling of the face, eyelids, lips, mouth, tongue and throat
• feeling faint
• tightness in your chest

Common side effects (between 1 in 100 and 1 in 10 people get them):

Reactions in the skin where you inject that cause:

• redness, pain, itching, and swelling for a couple of days
• these reactions are most common with the first injection, then drop to less than 3% after the third dose

Other side effects

Ofatumumab (Kesimpta) may cause liver damage. Symptoms of this include yellow skin and eyes, pain in the belly, feeling sick, dark pee and feeling weak.

Find out more about all the possible side effects of ofatumumab (Kesimpta)

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What tests do you need with ofatumumab (Kesimpta)

Tests before treatment begins

You’ll have blood tests to check your immunoglobulin levels. Your B cells make immunoglobulin to fight infections.

A blood test will show how well your liver is working. And it’ll show if you’ve ever had the liver infection hepatitis B. You might not be able to have ofatumumab (Kesimpta) if you have hepatitis B. That’s because this drug can cause liver damage or make hepatitis active again. 

Vaccination

Like most DMTs, this drug makes infections more likely. Before you start it, your neurologist will check if you have protection against some of the infections it puts you at risk of.

Your neurologist will check you’re up to date on your vaccines. This includes childhood ones like chickenpox (that vaccine protects you against shingles) and the MMR vaccine for measles, mumps and rubella. Some ‘live’ vaccines, like these two, aren’t safe to have once you’ve started many DMTs. Your MS team or GP can tell you whether a vaccine is ‘live’ or not.

You’ll have any vaccines you need a few weeks before you start this drug. It’s safe to have the annual flu jab while taking this DMT.

Read more about vaccines

Tests during treatment

You might need regular blood tests to check your liver and how your immune system is working.

Your neurologist might want you to have an MRI scan once a year to see if the drug is working. But how often you have scans depends on what your neurologist thinks you need. If your MS seems stable, you might have scans less often.

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Stopping ofatumumab (Kesimpta)

You should never stop taking a DMT without telling your doctor. With some DMTs there’s a risk of ‘rebound’ if you suddenly stop. This is when your MS gets much worse within a few weeks or months. There doesn’t seem to be a high risk of rebound with ofatumumab (Kesimpta).

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Ofatumumab (Kesimpta) and pregnancy, breastfeeding and contraception

Pregnancy

Ofatumumab (Kesimpta) doesn’t have a licence for use in pregnancy. If you can get pregnant, the drug’s makers say you should use contraception. If you stop this drug, they say you should keep using contraception for 6 months afterwards.  

But new guidelines for UK neurologists came out in 2022 that cover pregnancy and antiCD20 DMTs like ofatumumab (Kesimpta). Experts looked at what we know about these drugs and pregnancy. They followed what happened to babies whose mothers took these drugs while pregnant.  

These guidelines say you can be on these drugs if you want to get pregnant. They say you can take them up until the point you know you've become pregnant. You'll then usually stop treatment until your baby is born. Your neurologist might suggest you stop taking the drug a few months before you try to get pregnant. But there might be individual cases where a neurologist will recommend taking ofatumumab during a pregnancy.  

The 2022 guidelines say that if you stop taking ofatumumab, you can try to get pregnant straight away after your final injection. There’s no need for a ‘washout period’. That’s how long you must wait until the drug is out of your system and it’s safe to get pregnant. 

If you decide to stop this drug to have a baby, going back on it straight after the birth will cut your risk of a relapse. You’ll go back to taking starter doses for three weeks. Then you’ll skip a week before going back to monthly doses from week five. 

Because ofatumumab is still quite new, some neurologists are more cautious about pregnancy than the 2022 UK guidelines. 

If you want to have a child, discuss this with your neurologist. If you think you’ve become pregnant, let your medical team know at once. Never stop your DMT without first getting their advice. 

Breastfeeding

The new UK guidelines in 2022 said that it’s safe to breastfeed when taking antiCD20 drugs like ofatumumab (Kesimpta). They say the risk is low that the drug will get in the baby’s system. The guidelines say breastfeeding is encouraged. Ask your medical team for their advice.  

Contraception

If you can get pregnant, the makers of ofatumumab (Kesimpta) say you must use contraception while taking this drug (and for six months after your final dose). But official guidelines for UK neurologists from 2022 say this is too cautious. Experts looked at the evidence. They decided that getting pregnant while on drugs like ofatumumab is an option. So those guidelines have no recommendations about the need to use contraception. Speak to your MS team if you have questions.   

Read more about the 2022 guidelines, pregnancy, breastfeeding and contraception and DMTs

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