Ofatumumab linked to slightly more relapses than ocrelizumab, both very low

Design

Nationwide registry cohort with propensity-score weighting

Population

1,870 Danish adults with relapsing-remitting MS starting ofatumumab or ocrelizumab

Primary outcome

Annualised relapse rate and time to first relapse

Effect

ARR 0.05 vs 0.03; rate ratio 1.65 (1.09 to 2.50); disability worsening HR 0.83 (0.58 to 1.20)

The Danish Multiple Sclerosis Registry supplied 1,870 patients with relapsing-remitting MS who started ofatumumab (1,385) or ocrelizumab (485) between 2022 and 2025. Propensity-score weighting adjusted for baseline differences.

The annualised relapse rate was 0.05 with ofatumumab and 0.03 with ocrelizumab, a rate ratio of 1.65 (1.09 to 2.50). Time to first relapse, confirmed disability worsening, progression independent of relapse, and MRI activity did not differ significantly. Median follow-up was two to two and a half years.

Both drugs controlled relapses very well, and the absolute gap is about one extra relapse per 50 patient-years. The authors call the difference of limited clinical relevance, and residual confounding by indication is likely in an observational comparison. Route of administration, monitoring and cost remain reasonable grounds for choosing between them.

• Treat ofatumumab and ocrelizumab as broadly comparable high-efficacy options
• Let route, monitoring burden, pregnancy plans and cost guide the choice
• Check immunoglobulin levels periodically on long-term anti-CD20 therapy
• Complete vaccinations before starting B-cell depletion where possible

Why it matters

It is one of the first head-to-head real-world comparisons of two widely used anti-CD20 drugs.

Don't overread it

Observational data cannot exclude that sicker patients were steered to one drug.

The statistics, in plain English

A rate ratio of 1.65 sounds large, but when both rates are tiny (0.05 vs 0.03 relapses a year), the absolute difference is about two relapses per 100 patient-years.

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