Current RA treatments, while effective for some, often fall short of providing long-term remission owing to the disease’s complexity, leaving many patients cycling through therapies like methotrexate and biologics without sustained relief. Here, rosnilimab stands out as novel by targeting the PD-1 pathway, aiming to reset the immune system through the selective depletion of pathogenic PD-1+ T cells while preserving healthy immune function—an approach that could reduce the need for lifelong medication adjustments. The Phase 2b trial, with over 400 participants including both biologic-naïve and biologic-experienced patients, showcased significant improvements in disease activity and a favorable safety profile, prompting experts like Dr. Jonathan Graf of UCSF to note its potential to “reset the immune system” for a more durable response.
AnaptysBio’s investigational drug rosnilimab has delivered promising Phase 2b trial results for moderate-to-severe rheumatoid arthritis, hitting statistical significance on primary and key secondary endpoints with a safety profile matching placebo. This novel PD-1+ T cell modulator could redefine RA treatment, offering hope to patients underserved by current therapies, with more data and trials in other diseases like ulcerative colitis expected in 2025.
In the global Phase 2b RENOIR trial, rosnilimab, a first-in-class depleter and agonist of PD-1+ T cells, demonstrated statistically significant improvements in disease activity scores across all doses compared to placebo in 424 patients with moderate-to-severe RA. Notably, 69% of rosnilimab-treated patients achieved low disease activity at Week 14, with sustained responses observed up to Week 28. This novel mechanism, which resets immune homeostasis by targeting a central node of inflammation, offers a potential breakthrough for RA patients who remain underserved by existing therapies. Rosnilimab’s favorable safety profile, matching that of placebo, further underscores its promise. With additional data expected in Q2 2025 and a Phase 2 trial in ulcerative colitis underway, AnaptysBio is positioning rosnilimab as a transformative therapy across multiple inflammatory diseases.
The Phase 2b RENOIR trial met its primary endpoint, demonstrating a statistically significant mean change from baseline in DAS28‑CRP at Week 12 across all rosnilimab doses versus placebo. Rosnilimab also showed favorable results on key secondary endpoints (ACR20, ACR50, and CDAI low disease activity), with robust 69% CDAI LDA at Week 14—touted as among the highest responses ever reported at that time point. In terms of safety, the trial found no increase in serious infections, no malignancies, and no major adverse cardiovascular events (MACE) through Week 12, with rosnilimab‑treated patients overall experiencing a “placebo‑like” adverse event profile. This included no anaphylaxis or systemic hypersensitivity and a low incidence of injection site reactions comparable to placebo.
Daniel Faga, President and Chief Executive Officer of AnaptysBio, emphasized the significance of the findings in a press release, stating, “We are excited about these trial results and the impact they could have on patients living with RA. Rosnilimab is safe and well tolerated with the highest ever reported CDAI low disease activity at ~3 months that, to date, is sustained and potentially deepening over 6 months.”
Rheumatoid arthritis (RA), a chronic autoimmune disease, affects approximately 1.5 million people in the U.S., predominantly women.
Filed Under: Immunology, Rheumatology
