Orelabrutinib is a new drug treatment under investigation for relapsing remitting multiple sclerosis (MS). It is taken as a tablet, either once or twice daily.
Orelabrutinib for relapsing remitting MS: Phase II
- Orelabrutinib reduces the activity of B-cells and regulates immune cells called microglia which have been linked to MS progression.
- In relapsing remitting MS, orelabrutinib reduced the number of lesions on MRI.
- Side effects from early stage clinical studies have not been reported.
Orelabrutinib belongs to a group of medicines called Bruton's tyrosine kinase (BTK) inhibitors.
Bruton’s tyrosine kinase is an enzyme which is essential for the survival and activation of B-cells. B-cells are a type of white blood cell (lymphocyte) thought to be involved in the inflammation caused by MS which causes lesions in the brain and spinal cord and can lead to relapses. The enzyme also regulates immune cells in the brain called macrophages and microglia which have been linked to MS progression.
Orelabrutinib blocks the actions of the enzyme and it is thought that this will prevent the MS activity which leads to relapses as well as the longer term damage to nerve cells which causes progression.
Other BTK inhibitors in the MS drug pipeline include evobrutinib, tolebrutinib, fenebrutinib and remibrutinib.
Orelabrutinib is taken as a tablet, once or twice daily.
In a phase II study, 160 participants with relapsing remitting MS have been recruited to take one of 3 doses of orelabrutinib for 24 weeks or placebo for 12 weeks before switching to orelabrutinib. The main measure of the study is the number of new, active lesions visible on MRI scans at 12 weeks. Participants can continue to take orelabrutinib for up to 30 months.
In a company press release, initial results after 12 weeks of treatment were announced. Treatment with the highest dose of orelabrutinib resulted in 92% relative reduction in new active lesions visible on MRI scans.
Estimated completion date: February 2026.
Further details of this study
Late phase clinical trials have not yet been announced.
Side effects from the phase II study have not been reported.
Some cases of orelabrutinib-induced liver damage have been reported in clinical trials. The Food and Drug Administration in the States has placed a hold on recruitment to clinical trials while further investigations are carried out.