A recent Phase III study of fenebrutinib in relapsing multiple sclerosis demonstrated that fenebrutinib, an investigational Bruton’s tyrosine kinase inhibitor, reduced the annualized relapse rate by 51 percent compared to teriflunomide during a period of at least 96 weeks of treatment. This was consistent with the FENhance 2 results showing which show a 59 percent reduction in annualized relapse rate. Together, these results equate to approximately one relapse every 17 years. Secondary endpoints in both relapsing MS studies show significant reductions in brain lesions.

The positive FENhance 1 study follows positive results for FENhance 2 in relapsing MS and for FENtrepid in primary progressive MS – which were both announced in November. The collective positive results across all three studies demonstrate fenebrutinib consistently shows a benefit on relapsing and progressive disease biology.

In both relapsing MS studies, liver transaminase elevations were comparable with teriflunomide. In the FENhance 1 study, there was one Hy’s Law case in the fenebrutinib arm and one in the teriflunomide arm. Both cases were asymptomatic and resolved after study drug discontinuation. There were no additional Hy's Law cases across all of the fenebrutinib clinical development program in MS or in other autoimmune diseases. 

In the FENhance 1 and 2 studies in relapsing MS, 1 fatal case was reported in the teriflunomide arm and 8 fatal cases with various causes and at different points in treatment in the fenebrutinib arms. Further analyses are ongoing to better understand these findings.

Fenebrutinib targets cells in the immune system known as B cells and microglia. Targeting B cells helps control the acute inflammation that causes relapses, while targeting microglia inside the brain addresses the chronic damage that is thought to drive long-term disability progression. Fenebrutinib, a noncovalent BTK inhibitor, is designed to have high potency, selectivity, and reversibility. This design allows it to act throughout the body, and also to cross the blood-brain barrier into the central nervous system targeting chronic inflammation.

Full data from the FENhance 1 and 2 studies will be shared at the American Academy of Neurology Annual Meeting 2026 in April in Chicago, and submitted to regulatory authorities together with data from the FENtrepid study.