New trial testing vaccine against common virus to treat relapsing MS

Vaccines are traditionally used to stop you getting diseases you can catch from other people, like COVID-19.  But in the Horizon trial, researchers are testing if a vaccine may have potential as a treatment for MS instead. 

This is still at quite an early stage of research, so we won’t know the answers for many years. 

What is EBV?

EBV is a common virus that infects more than nine in ten people in their lifetime. For most people, it doesn’t cause any symptoms. But for some, it causes glandular fever. Once you’ve been infected, the virus usually stays hidden in your immune cells for life. 

Why target EBV in MS?

In MS, these immune cells attack your myelin. So some researchers think EBV could be continuing to influence the cells long after infection. The dormant virus could be pushing certain immune cells to attack myelin. And driving ongoing MS activity. This is the focus of the Horizon trial.

Lots of evidence suggests EBV may play a key role in causing MS too. There’s no vaccine to prevent us being infected with EBV yet. But researchers are also exploring whether stopping EBV infection might one day prevent MS. 

Read more about research into EBV and MS

Why use a vaccine? 

Most existing disease modifying therapies (DMTs) work by suppressing the immune system. A vaccine would work a bit differently. 

The immune system in people with MS is already aware of EBV. But it might need help keeping it under control. The researchers hope their vaccine will do this by giving the body instructions to make a little harmless piece of the virus. So the immune system is better able to recognise it and stop it from continuing to cause damage. 

How will the Horizon trial work?

People taking part will be given either the vaccine or a placebo (dummy drug) injection. The vaccine uses the same mRNA technology as the company’s COVID-19 vaccine. 

It’s a phase 2 trial. So they’re checking whether the vaccine is safe and what side effects it might cause. 

But they’ll also be looking for signs it’s slowing progression. They’ll use MRI scans to see if the vaccine affects lesions. And they’ll monitor changes in disability scores. 

Who can take part?

The trial will involve up to ten sites across the UK, led by the University of Edinburgh. The team are recruiting people who’ve been diagnosed with relapsing MS in the last two years. This can include clinically or radiologically isolated syndrome. 

They’re aiming to recruit around 25 people to take part in the UK. And 180 people in total around the world.

To find out more about taking part in the trial you can search ‘Multiple sclerosis mRNA’ on the Be Part of Research website or speak to your MS team. You can go to our Be in a Study page to see other trials that are recruiting people with relapsing or progressive MS.  

What could this mean for people with MS?

DMTs that work by suppressing the immune system come with infection risks. But it might be that the most important immune cells to stop are the EBV-infected cells. And a vaccine may be able to do this in a much more targeted way. 

The trial runs until 2029. If it’s successful, there would need to then be a larger phase 3 trial to confirm whether it slows MS worsening.

Professor David Hunt, national Chief Investigator for the trial and Director of the MS and Neuroimmunology Hub at the University of Edinburgh’s Anne Rowling Clinic, said: “This is an important and innovative trial to treat multiple sclerosis by targeting EBV infection using a vaccine. Currently, almost all of our disease-modifying treatments for multiple sclerosis work by suppressing the body’s immune system. The discovery that EBV plays an important role in the development of multiple sclerosis is opening new avenues for treating the condition.”

What are we doing to understand EBV?

We’ve been supporting research into a possible role for EBV in triggering MS, or driving worsening, for many years. Right now, projects include: 

• Dr Margarita Dominguez-Villar researching how the immune cells of people with MS react differently to EBV
• Dr Claire Shannon-Lowe studying how EBV changes the immune cells to discover the cause of MS