A Cambridge-led clinical trial has raised hopes for a new class of therapies for multiple sclerosis (MS), after finding that combining a common diabetes drug with an antihistamine can partially repair nerve damage.
The CCMR Two trial tested clemastine, an antihistamine, with metformin, a diabetes medication, in 70 patients with relapsing MS. After six months, participants receiving the drugs showed measurable improvements in nerve function compared with those on placebo.
Electrical signals between the eyes and brain travelled faster by an average of 1.3 milliseconds, indicating some restoration of damaged myelin sheaths—the protective coating around nerve fibres that is attacked in MS. However, the improvements were too small for patients to notice a change in vision or disability over the trial period.
“It’s smaller than we were hoping for,” said Dr Nick Cunniffe, neurologist at the University of Cambridge and lead investigator. “My conclusion is that the drugs have a biological effect to promote remyelination, but we need to be clear that people do not feel better on these drugs over six months.”
Nearly 3 million people worldwide live with MS, including over 150,000 in the UK. The condition, often diagnosed in young adults, causes progressive disability as the immune system destroys myelin and eventually nerve cells. Current treatments slow disease activity but cannot repair lost myelin.
Earlier research suggested clemastine alone could stimulate remyelination, but the effect was modest. Metformin was found to potentially enhance that process. The Cambridge trial is the first to combine both drugs in MS patients.
Emma Gray of the MS Society, which funded the trial, called the results “really positive proof of concept,” adding that longer studies would be needed before any clinical benefit could be expected.
Researchers cautioned that patients should not attempt to obtain or self-administer the drugs outside clinical trials, as both clemastine and metformin caused side effects in the study, including fatigue and diarrhoea.
Experts emphasised that remyelination therapies would not restore nerves already lost, but could slow or prevent permanent disability if started early. Professor Jonah Chan of UCSF, who has led related work, said: “Remyelination is the critical path to preventing permanent disability in MS … the only immediate hope for restoring function, albeit in limited contexts.”
Larger, longer trials are now needed to determine whether such treatments could translate into meaningful improvements in quality of life for people living with MS.
