Anaptys Announces Positive Rosnilimab Data Updated Through Six Months in Robust Phase 2b Trial in RA

Core Insights - AnaptysBio's investigational drug rosnilimab shows a best-in-disease profile for treating moderate-to-severe rheumatoid arthritis (RA), demonstrating JAK-like efficacy and durable responses [1][2][3] Efficacy and Clinical Outcomes - In a Phase 2b trial with 424 patients, rosnilimab achieved significant clinical improvements, including low disease activity (LDA) and remission on the Clinical Disease Activity Index (CDAI) [1][2][3] - By Week 12, 45% of patients achieved CDAI LDA, increasing to 69% by Week 14, indicating a strong response to treatment [3][4] - Rosnilimab demonstrated a rapid onset of ACR20 response, comparable to upadacitinib, with a substantial decrease in C-reactive protein (CRP) levels [2][3] Safety and Tolerability - Rosnilimab exhibited a favorable safety profile, with no treatment-related serious adverse events (SAEs) reported and a low incidence of injection site reactions [10][11] - Less than 2% of patients discontinued treatment due to adverse events, indicating good tolerability [10][11] Market Potential - The findings suggest rosnilimab could capture a significant share of the ~$20 billion U.S. RA market, with potential for extended dosing intervals [2][3] - The company aims to complete ongoing studies for rosnilimab in ulcerative colitis, with initial data expected in Q4 2025 [2][14] Mechanism of Action - Rosnilimab targets PD-1+ T cells, aiming to restore immune homeostasis and reduce inflammation associated with RA [19][21] - The drug demonstrated a ~90% reduction in PD-1 T cells and a ~50% reduction in PD-1+ T cells, indicating robust pharmacological activity [8][19] Future Developments - AnaptysBio plans to advance rosnilimab's clinical development and explore its application in other autoimmune diseases [21][22] - The company is committed to developing innovative treatments that address the long-term needs of patients with chronic inflammatory conditions [21][22]