Positive Week 12 Results for Rosnilimab in Patients with RA

Week 12 results from the global phase 2b Renoir study (NCT06041269) demonstrated positive results for in reducing the signs and symptoms of rheumatoid arthritis (RA) with rosnilimab. This study evaluated the agent’s safety, efficacy, tolerability, pharmacokinetics and pharmacodynamics in patients with moderate to severe RA compared with placebo.¹

Rosnilimab is a therapeutic antibody that targets PD-1 on the surface of activated T cells, influencing the pathogenesis of inflammatory diseases, such as RA and ulcerative colitis. Rosnilimab is a targeted therapy intended to restore the immune system back to a homeostatic state by depleting PD-1^high T cells and distressing remaining PD-1+ T cells. This process is expected to reduce T cell proliferation, migration, cytokine secretion, plasma cell generation and autoantibody levels in both inflamed tissue and the periphery.²

Methods

The Renoir study enrolled patients (N=424) with a mean baseline disease activity score-28 joints (DAS-28) C-reactive protein (CRP) score of 5.64 and a mean baseline of clinical disease activity index (CDAI) score of 37.7. Enrolled patients were either biologic or targeted synthetic disease-modifying antirheumatic drug (DMARD) naïve (59%; n=250) or biologic or targeted synthetic DMARD experienced (41%; n=174). Patients who had taken DMARDs reported the prior use of at least one biologic or targeted synthetic therapy. These therapies included tumor necrosis factor (TNF) α inhibitors, B cell inhibitors, selective costimulatory modulators or Janus kinases (JAK) inhibitors. All patients received rosnilimab along with background conventional DMARDs. (Note: The study did not specify which conventional DMARDs patients used.)

During the study, patients were randomized to receive either 100 mg of subcutaneously rosnilimab every four weeks, 400 mg of rosnilimab every four weeks, 600 mg of rosnilimab every two weeks or placebo. The study’s primary end point was the mean change from baseline in DAS-28 CRP score at week 12 for all three doses of rosnilimab compared with placebo. Secondary end points were assessed at both weeks 12 and 14.

After week 14, rosnilimab-treated patients who achieved a CDAI low disease activity (LDA) score of less than 10, continued their assigned treatment through week 28 in a blinded, all-active treatment period.

The Results

All three doses of rosnilimab achieved statistical significance in the mean change from baseline of DAS-28 CRP at week 12 compared with placebo, as well as statistical significance on key secondary end points of ACR20, ACR50 and CDAI LDA.

Of rosnilimab-treated patients, 69% achieved CDAI LDA at week 14 and seemed to have sustained CDAI LDA and ACR50 responses—potentially developing toward ACR70 responses for week 28. Investigators also observed a reduction of PD-1^high T cells, an increase in regulatory T cells and a reduction in CRP in patients in all rosnilimab treatment groups compared with placebo. (Note: Tregs are a subset of CD4+ T cells that maintain immune tolerance and prevent autoimmune diseases by suppressing immune responses. They suppress the activity of other immune cells, helping to maintain a balance in the immune system.)

Rosnilimab was safe and well tolerated in patients, who had similar adverse event rates as patients who received placebo. Data through week 12 showed no malignancies or major adverse cardiovascular events, no increase in serious infections and no anaphylaxis or systemic hypersensitivity reactions. Additionally, the study also showed a low incidence of injection site reactions in patient who received rosnilimab, similarly to those who received placebo.

Rosnilimab is currently under clinical investigation and has not been evaluated by a regulatory authority. It continues to be evaluated as a treatment for RA and is also in clinical trials for ulcerative colitis.

Michele B. Kaufman, PharmD, BCGP, is a freelance medical writer based in New York City and a pharmacist at New York Presbyterian Lower Manhattan Hospital.

References

1. A study of efficacy and safety of rosnilimab in subjects with moderate to severe rheumatoid arthritis (RENOIR) [NCT06041269]. AnaptysBio Inc. ClinicalTrials.gov. 2024 Nov 25.
2. Anaptys announces rosnilimab achieved positive results in RA phase 2b trial and highest ever reported CDAI LDA response over 6 months [news release]. AnaptysBio Inc. 2025 Feb 12.