Phase 2b data show that rosnilimab is effective in rheumatoid arthritis

Rosnilimab, a monoclonal antibody that selectively depletes pathogenic PD-1 high T cells, showed improvements in disease activity with acceptable safety compared with placebo in participants with moderate-to-severe rheumatoid arthritis.

Prof. Paul Emery (University of Leeds, UK) presented data from the multicentre, randomised, double-blind, phase 2b RENOIR trial (NCT06041269) in adults with rheumatoid arthritis [1]. Participants were included if they had seropositive rheumatoid arthritis, ≥6 swollen and ≥6 tender joints, high-sensitivity C-reactive protein (hs-CRP) ≥3 mg/L, and were receiving 1 or 2 disease-modifying antirheumatic drugs (DMARDs) initiated ≥3 months prior, but were excluded if they had failed ≥3 DMARDs. Randomisation (1:1:1:1) was carried out to subcutaneous rosnilimab 100 mg every 4 weeks, 400 mg every 4 weeks, 600 mg every 2 weeks, or placebo. A potential extension of 16 weeks was allowed for rosnilimab participants. The primary endpoint was the change in Disease Activity Score 28 with CRP (DAS28-CRP) from baseline to week 12. In total, 424 participants were randomised.

All doses of rosnilimab met the primary endpoint, with mean changes from baseline of -2.06, -2.12, and -2.06 for the 100 mg, 400 mg, and 600 mg arms, respectively, compared with -1.69 for placebo (P<0.01). Additionally, all rosnilimab doses led to higher proportions of participants achieving ACR20 compared with placebo. Participants who entered the extended treatment period showed sustained responses in multiple efficacy outcomes. Overall, rosnilimab was well tolerated, with discontinuation rates similar to those in the placebo group. Opportunistic infections were lower with rosnilimab than with placebo, but 1 major cardiovascular adverse event was reported in a rosnilimab-treated participant. There were no malignancies or deaths.

“In summary, the primary endpoint of mean change from baseline in DAS28-CRP was achieved across all doses of rosnilimab versus placebo, as was ACR20,” concluded Prof. Emery. “Safety data through week 38 demonstrated that rosnilimab was well tolerated, with no malignancies or deaths.”

1. Graf J, et al. Rosnilimab, a selective and potent depleter of pathogenic T cells, demonstrates efficacy, safety, and translational proof of mechanism in a rheumatoid arthritis phase 2b trial. ACR Convergence, 24–29 October 2025, Chicago, IL, USA.

Medical writing support was provided by Mihai Surducan, PhD.

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Posted on 30 October 2025