Ibudilast is an experimental drug treatment for secondary and primary progressive MS. It is taken as a tablet, twice daily.
Ibudilast for secondary progressive MS: Phase II
Ibudilast for primary progressive MS: Phase II
- Ibudilast acts on a number of cell processes associated with nerve damage and myelin repair. Previous studies have suggested it may have a neuroprotective effect
- In a phase II study, ibudilast slowed down the loss of brain volume in people with progressive MS by almost one half compared to placebo
- The most common side effects associated with ibudilast included nausea, diarrhoea and abdominal pain, depression, rash and fatigue
Ibudilast inhibits the enzyme phosphodiesterase. It reduces inflammation and acts on a number of biochemical processes in cells associated with nerve damage and myelin repair. Previous studies have suggested it may have a neuroprotective effect.
Ibudilast is used in Japan and Korea to treat asthma and some complications of stroke.
Ibudilast is taken as a tablet, twice daily.
In this phase II study, 297 people with relapsing MS took one of two doses of ibudilast or placebo for 12 months. The main measure of the study was the total number of active lesions seen on MRI. Secondary measures included relapse rate, EDSS, lesion volume and brain volume.
There was no difference between the two groups in the number of active lesions or relapse rate. However, compared to placebo, fewer people taking ibudilast showed signs of progression.
SPRINT-MS was a phase II study designed to assess the effectiveness and safety of ibudilast in people with progressive MS. 255 people with secondary and primary progressive MS took either ibudilast or placebo as tablets twice daily for nearly two years. MRI was used to measure brain volume at the beginning and end of the study. Compared to placebo, ibudilast slowed down the loss of brain volume (brain atrophy) by 48%. A subsequent analysis reported that ibudilast significantly slowed brain atrophy in primary progressive MS (PPMS), but not in secondary progressive MS (SPMS). It was suggested that the difference may be related to faster atrophy rates among people with PPMS who received placebo, compared with those with SPMS who received placebo.
Loss of brain volume is linked to cognitive and physical disability in MS and is used as a marker for MS progression; slowing down the rate at which brain volume is lost indicates that ibudilast is slowing down progression in MS. Another advanced MRI imaging technique also provided some evidence that ibudilast reduced further damage to myelin and nerve cells.
Further analysis of the trial data published in a company press release compared disability progression in subgroups of participants. These suggested that reduction in the risk of increased disability was highest for people with secondary progressive MS without relapses.
According to a company press release, a phase III study is being planned which will explore the potential of ibudilast in more detail. In a 2021 press release, the company indicated that they are continuing to engage with potential partners that could help fund the study.
In the SPRINT-MS study, the most common side effects associated with ibudilast included gastrointestinal problems such as nausea, diarrhoea and abdominal pain, as well as depression, rash and fatigue.