AnaptysBio announces Phase 2b trial results for rosnilimab in RA

AnaptysBio (ANAB) announced late-breaking data from the robust, global 424-patient Phase 2b trial of rosnilimab, a selective and potent pathogenic T cell depleter, in rheumatoid arthritis at the American College of Rheumatology Convergence 2025 in Chicago. New study results showed that positive Week 12 data across multiple higher-order response measures continue to deepen into Week 28 regardless of prior treatment. These results were then durable for at least three months off drug. Additionally, rosnilimab was well-tolerated with no treatment-related serious adverse events and no malignancies in rosnilimab-treated patients through end-of-trial follow-up. Paul Emery, M.D., professor of rheumatology at the University of Leeds and Leeds Biomedical Research Centre, U.K., presented data that show: As previously reported, at Week 12, statistically significant and clinically meaningful efficacy was achieved on the primary endpoint DAS28-CRP, as well as for ACR20, for all doses, including monthly doses; At Week 28, CDAI LDA, CDAI remission and ACR50/70 rates continued to improve independent of prior treatments, including anti-TNFalpha, anti-IL6R or JAK inhibitors; Similar effects were seen for patients previously treated with at least two prior biologic or targeted synthetic disease-modifying antirheumatic drug classes, particularly at the mid and high doses; Week 28 responses across multiple clinically meaningful measures, including CDAI LDA, mean CDAI, mean DAS28-CRP and ACR50/70, were durable off drug through at least three months after the last rosnilimab dose; Through Week 38, safety data demonstrated rosnilimab was well-tolerated, with no malignancies and no deaths; By Week 6, Tph cells were reduced greater than 90% in the periphery for all doses and the synovium at the two highest doses; Highly statistically significant reductions observed in T cell and B cell activation in synovial biopsies, with deeper reductions seen in CDAI LDA responders.