MS activity remains low on long-term fenebrutinib

Participants receiving the potent and highly selective Bruton’s tyrosine kinase (BTK) inhibitor fenebrutinib maintained low disease activity in the open-label extension (OLE) of the FENopta study. Participants treated for 1 year had near complete suppression of acute inflammatory disease activity. Fenebrutinib maintained a favourable safety profile.

Fenebrutinib 200 mg twice daily reduced acute inflammatory disease activity and demonstrated CNS penetration in people with relapsing MS in the 12-week, placebo-controlled, phase 2 FENopta trial (NCT05119569). Participants were 18–55 years old at inclusion, had relapsing MS, and an Expanded Disability Status Scale (EDSS) score of 0–5.5 at baseline. At the end of the double-blind study period, all 99 eligible participants joined the OLE. The 48-week results were presented by Prof. Amit Bar-Or (University of Pennsylvania, PA, USA). Of the OLE participants, 65 had received fenebrutinib and 34 placebo in the original study.

Disease activity was very low in the OLE. Of the 99 participants, 90% met NEDA criteria throughout 48 weeks. The annualised relapse rate (ARR) was 0.04, and 96% was relapse-free during the OLE. At week 48, 99% of the participants were free of new T1 gadolinium-enhancing (Gd+) lesions. The mean number of new Gd+ lesions was 0.015 per scan (n=67). The ARR of new or enlarging T2-weighted lesions was reduced to 0.16 in the original fenebrutinib group and to 0.13 in the original placebo group. Fenebrutinib was associated with a decrease in T2-weighted lesion volume of -0.33 in the original fenebrutinib group. At week 48, the median EDSS score had not changed.

Reductions in immunoglobulin (Ig) and B-cell levels were also observed, consistent with fenebrutinib’s mechanism of action.

In addition, fenebrutinib maintained a favourable safety profile mirrored by the high retention rate. The most common adverse events were urinary tract infection (8%), COVID-19 (7%), and pharyngitis (5%). One participant had 2 serious AEs (urinary tract infection and nephrolithiasis).

1. Bar-Or A, et al. Fenebrutinib maintains low disease activity in relapsing multiple sclerosis: Clinical, safety and biomarker results from the FENopta open-label extension. P091, ACTRIMS 2025, 27 February–01 March 2025, West Palm Beach, FL, USA.

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Posted on 28 March 202528 March 2025