Rosnilimab Continues Best-in-Disease Profile Responses for Rheumatoid Arthritis

Rosnilimab has continued to demonstrate a best-in-disease profile in patients with moderate-to-severe rheumatoid arthritis (RA) in updated 6-month data from the phase 2b RENOIR trial.1 The new data further support the use of rosnilimab for RA, continuing on the historic responses demonstrated earlier this year in 12-week data.2

"RA is a chronic disease that often begins in early adulthood, making it critical to effectively control disease activity over a patient's entire lifetime and prevent damage to joints and other organs, reduce pain and improve quality of life. Witnessing rosnilimab, with its novel mode of action, dramatically reduce RA disease activity through 6 months in most patients, whether having failed multiple classes of b/tsDMARD therapies or b/tsDMARD-naïve, is truly exciting for patients living with this disease and the field of RA treatment,” study investigator Jonathan Graf, MD, professor of Medicine, Division of Rheumatology at the University of California, San Francisco, said in a statement.1 “Additionally, impressive translational data provide further evidence that by targeting specific PD-1 expressing cells, rosnilimab has a substantial impact downstream on multiple known pathways that drive RA pathogenesis, with the potential to restore immune homeostasis necessary to achieve meaningful, long-lasting disease remission.Developing innovative and safe treatment options with novel modes of action for long-term use is crucial to meet the urgent needs of today's patients with lifelong disease.”

By 3 months, most patients receiving rosnilimab showed clinical and symptomatic improvement. All 3 doses of rosnilimab produced statistically significant reductions from baseline in DAS28-CRP and ACR20 at Week 12 compared with placebo. During the placebo-controlled period, both b/tsDMARD-naïve and b/tsDMARD-experienced patients demonstrated rapid ACR20 responses and reductions in C-reactive protein (CRP), consistent with Phase 2b upadacitinib results.

Rosnilimab showed efficacy similar to JAK inhibitors, with responses deepening through 6 months in CDAI low disease activity (LDA), CDAI remission, and ACR70, particularly in b/tsDMARD-experienced patients at the 400mg Q4W and 600mg Q2W doses. At baseline, patients had high disease activity (mean CDAI 38; median 36). In the intent-to-treat (ITT) population (n = 318), CDAI ≤10 was achieved by 45% at Week 12 and by 69% (n = 220) across doses at Week 14, which was the cutoff for continuing into the all-active treatment period. This requirement set a ceiling on Week 28 response rates under NRI analysis. Anaptys noted that 12 patients who improved after Week 14 could not continue and were imputed as non-responders, although including them would have raised Week 28 CDAI LDA to 73% (n = 232 of 318). Among ineligible patients, ~50% achieved ACR20 at Week 14 and were trending toward CDAI LDA.1

Responses were durable, with CDAI LDA maintained for at least 2 months off treatment. By Week 34, 83% of CDAI LDA responders remained in LDA, while the remaining 17% were close to the threshold (median CDAI 13). Patient-reported outcomes showed improvements through Week 28. Pain VAS declined from ~65 at baseline to ~15 (a ~50-point change, where MCID is ~10), and HAQ-DI decreased from ~1.6 to ~0.7 (a 0.9-point change, where MCID is 0.22).1

Clinical findings were supported by biomarker data. Mean CRP decreased by ~50% through Week 28. Blood samples showed ~90% reduction in PD-1high T cells, ~50% reduction in PD-1+ T cells, and an increase in total Tregs, resulting in stable total T cell counts and improved immune balance. Synovial biopsies from the most affected joint showed ~90% reduction in PD-1+ T cells at the 400mg Q4W and 600mg Q2W doses compared with the 100mg Q4W dose. Gene expression in synovium revealed reductions in T cell and B cell activation pathways, as well as decreases in TNF and IL-6–related pathways.

“This was a robust and well-controlled Phase 2b study with more than 300 patients treated with rosnilimab for up to 6 months. To date, rosnilimab has shown a safe and well tolerated profile with almost all patients choosing to stay on therapy through the end of the study. Rosnilimab has not demonstrated any concerning safety trends or signals, such as those seen with the JAK inhibitors and most other biologics,” Paul Emery, MD, Versus Arthritis professor of rheumatology at the University of Leeds and Leeds Biomedical Research Centre, UK, added.1 “This is remarkable, given these patients have a two-to-threefold increased risk of comorbidities such as infections, cardiac events and malignancies, before accounting for the impact of background DMARDs, mostly methotrexate.”

REFERENCES

1. Anaptys Announces Positive Rosnilimab Data Updated Through Six Months in Robust Phase 2b Trial in RA. News release. Anaptys. June 3, 2025. https://www.globenewswire.com/news-release/2025/06/03/3093190/0/en/Anaptys-Announces-Positive-Rosnilimab-Data-Updated-Through-Six-Months-in-Robust-Phase-2b-Trial-in-RA.html

2. Anaptys Announces Rosnilimab Achieved Positive Results in RA Phase 2b Trial and Highest Ever Reported CDAI LDA Response Over 6 Months. News release. Anaptys. February 12, 2025. https://www.globenewswire.com/news-release/2025/02/12/3024946/0/en/Anaptys-Announces-Rosnilimab-Achieved-Positive-Results-in-RA-Phase-2b-Trial-and-Highest-Ever-Reported-CDAI-LDA-Response-Over-6-Months.html