712 - Positive 52-week maintenance data observed with rademikibart in patients with moderate-to-severe atopic dermatitis (S<u>EASI</u>DE CHINA)

Abstract Introduction/Background Rademikibart (formally, CBP-201) is a next-generation optimized monoclonal antibody targeting the IL-4Rα subunit. Rademikibart achieved all Week 16 primary and secondary endpoints in a global Phase 2 atopic dermatitis (AD) trial (WW001; NCT04444752) and a pivotal trial in China (SEASIDE CHINA or CN002; NCT05017480)1 in patients with moderate-to-severe AD. Objectives Long-term treatment of atopic dermatitis is essential for continued symptom management, prevention of complications, and improvments in the patient's quality of life. In this report, we now report Stage 2, long-term 52-week data from the SEASIDE CHINA pivotal trial. Methods Adults (n=318) and adolescents (n=12) (IGA ≥3, EASI ≥16, BSA ≥10%, PP-NRS ≥4) were randomized (2:1) to rademikibart (300mg Q2W) or placebo for 16 weeks (Stage-1). EASI-50 responders, regardless of Stage-1 treatment, were re-randomized to Q2W (n=113) or Q4W rademikibart (n=112). Non-responders received open-label Q2W rademikibart (n=86). Results Initial baseline mean EASI was 29.3 (range, 16.0–72.0) with 54.7% IGA4 for Stage 1 responders and 23.7 (16.0-66.6) with 51.2% respectively for non-responders. In patients who achieved IGA 0/1, 76.0% (Q2W) and 87.2% (Q4W) maintained their response at Week 52. Similarly, 91.7% (Q2W) and 91.9% (Q4W) maintained their EASI-75 response. From Week 16 to Week 52, 28.2% (Q2W/Q2W; n=91) and 20.8% (Q2W/Q4W; n=91) additional patients achieved IGA 0/1, and 16.3% (Q2W/Q2W) and 11.0% (Q2W/Q4W) additional patients achieved EASI-75. Of patients with ≥4-point reduction in PP-NRS, 81.6% (Q2W) and 95.2% (Q4W) maintained that response at Week 52. A ≥5-point reduction on the DLQI was maintained by 93.4% (Q2W) and 90.0% (Q4W). For 26 rademikibart non-responders (Stage-1), EASI scores improved by 45% with 51.4% acheiving EASI-75 by Week 52. Treatment with rademikibart was generally well tolerated. Conclusion Maintenance data with rademikibart are compelling and build upon strong results shown in Stage 11. High rates of maintained efficacy with Q4W dosing, additional gains in efficacy with continued treatment, and maintenance of ciniically meaningful changes in pruitis and QOL were observed.