Anaptys Reports Positive Rosnilimab Phase 2b RA Trial Results and Record CDAI LDA Response

SAN DIEGO, CA, USA I February 12, 2025 I AnaptysBio, Inc. (Nasdaq: ANAB), a company specializing in advanced immunology therapeutics, recently unveiled new data from its Phase 2b RENOIR trial. This study investigates rosnilimab, a promising treatment for moderate-to-severe rheumatoid arthritis (RA), focusing on its effects on PD-1+ T cells. The trial involved 424 participants from the U.S., Canada, and Europe, assessing the efficacy and safety of this potential therapy.

The RENOIR trial specifically targeted patients with moderate-to-severe RA who were already on conventional disease-modifying antirheumatic drugs (cDMARDs) like methotrexate. Participants, with an average baseline disease activity index score of 37.7, were either new to biologic or targeted synthetic DMARDs (b/tsDMARDs) or had previous experience with them. Those with prior experience had used at least one biologic or targeted synthetic therapy.

In the trial, participants were randomly assigned to receive varying doses of rosnilimab: 100mg every four weeks, 400mg every four weeks, or 600mg every two weeks, along with a placebo group. The primary goal was to measure changes in disease activity after 12 weeks, with secondary objectives assessed at both 12 and 14 weeks. Patients showing low disease activity after 14 weeks continued their assigned treatment up to 28 weeks in an all-active, blinded phase.

Rosnilimab achieved remarkable results, meeting its primary endpoint by showing significant improvements in disease activity scores at Week 12 across all dosage groups compared to the placebo. The treatment also excelled in secondary measures, including ACR20, ACR50, and low disease activity according to the Clinical Disease Activity Index (CDAI). Notably, 69% of patients on rosnilimab reached low disease activity by Week 14, with sustained and potentially improving responses through Week 28.

The trial also highlighted rosnilimab’s robust impact on specific immune cells. There was a rapid and sustained reduction in PD-1 high T cells and PD-1+ T cells, while total regulatory T cells increased. This combination resulted in a balanced immune response without significantly affecting total T cell counts. Furthermore, a notable reduction in C-reactive protein (CRP), a marker of inflammation, was observed throughout the trial in those treated with rosnilimab.

Safety assessments revealed that rosnilimab was well tolerated, with adverse events similar to those seen in the placebo group. Common severe adverse events included pneumonia, meniscus tear, and anaphylaxis due to a wasp sting. Despite these, the overall safety profile was consistent with earlier studies.

Healthcare professionals view rosnilimab as a promising new option for RA treatment. Paul Emery, M.D., emphasized the importance of developing therapies with novel action mechanisms, especially since no new drug classes for RA have been approved in recent years. The trial's results indicate that rosnilimab not only offers effective disease management but also maintains a favorable safety profile, making it a valuable addition to RA treatment options.

Rosnilimab, an innovative antibody, targets the PD-1 receptor on T cells, which is key in inflammatory diseases like RA and ulcerative colitis. By depleting PD-1 high T cells and stimulating the remaining PD-1+ T cells, rosnilimab aims to reset the immune system to a balanced state, reducing inflammation and autoantibody levels.

As the trial progresses, AnaptysBio anticipates sharing more comprehensive six-month data in the second quarter of 2025. They also plan to report findings from a Phase 2 trial of rosnilimab in ulcerative colitis later this year. These developments hold promise for a broader application of rosnilimab in treating complex autoimmune conditions.