POS1534 BIMEKIZUMAB MAINTAINED EFFICACY RESPONSES THROUGH 52 WEEKS IN BIOLOGIC DISEASE-MODIFYING ANTIRHEUMATIC DRUG-NAÏVE PATIENTS WITH PSORIATIC ARTHRITIS WHO WERE RESPONDERS AT WEEK 16: RESULTS FROM BE OPTIMAL, A PHASE 3, ACTIVE-REFERENCE STUDY

Background Given the chronic, long-term nature of psoriatic arthritis (PsA), sustaining high levels of disease control with treatment is important. Assessing the maintenance of response in patients (pts) that achieve treatment targets is of interest, particularly as pts can experience loss of response with long-term therapy [1]. Bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A, has demonstrated rapid, statistically significant and clinically meaningful joint and skin efficacy responses at Week (Wk) 16 versus placebo (PBO), in pts with PsA [2,3]. Responses were sustained to Wk 52 [4]. Objectives To report the maintenance of response in joint and skin efficacy outcomes to 52 wks in BKZ-treated pts with PsA who were responders at Wk 16. Methods BE OPTIMAL (NCT03895203) included a 16-wk double-blind, PBO-controlled period, and a 36-wk active treatment-blind period. Biologic disease-modifying antirheumatic drug (bDMARD)-naïve pts were eligible if they had adult-onset, active PsA with ≥3 tender and ≥3 swollen joints, and ≥1 active psoriatic lesion and/or history of psoriasis. Pts were randomised 3:2:1 to subcutaneous BKZ 160 mg every 4 wks (Q4W), PBO or reference arm (adalimumab 40 mg every 2 wks). At Wk 16, PBO pts switched to subcutaneous BKZ 160 mg Q4W (PBO/BKZ). Maintenance of response is reported as the percentage of BKZ-treated pts who achieved a response at Wk 16, who maintained that response at Wk 52. Data are reported for pts randomised to subcutaneous BKZ 160 mg Q4W at baseline. Endpoints include American College of Rheumatology (ACR)20/50/70, Psoriasis Area and Severity Index (PASI)75/90/100, minimal and very low disease activity (MDA, VLDA), and Disease Activity Index for PSoriatic Arthritis (DAPSA) remission or low disease activity (REM+LDA; ≤14) and remission (REM; ≤4) responses. Wk 16 responders are reported using non-responder imputation (NRI); maintenance of response to Wk 52 is reported using NRI and observed case (OC) data. The number of treatment-emergent adverse events (TEAEs) to Wk 52 are reported for pts who received ≥1 dose of BKZ, including pts who switched from PBO to BKZ at Wk 16. Results At baseline, 431 pts were randomised to BKZ 160 mg Q4W; 217/431 (50.3%) had psoriasis affecting ≥3% body surface area (BSA). 414/431 (96.1%) pts completed Wk 16 and 383 (88.9%) completed Wk 52. The majority of pts who achieved responses at Wk 16 maintained their response at Wk 52, across a range of joint and skin outcomes (Figure 1). At Wk 16, 268 (62.2%), 189 (43.9%) and 105 (24.4%) pts achieved ACR20/50/70, respectively. Of those responders, ACR20/50/70 responses were maintained at Wk 52 by over 80% of pts: 88.4%, 86.8%, 82.9% (NRI); 92.9%, 91.1% and 87.9% (OC). Of 217 pts with psoriasis affecting ≥3% BSA at baseline, 133 (61.3%) and 103 (47.5%) achieved PASI90/100 at Wk 16. The majority of pts maintained the response at Wk 52: 82.7%, 79.6% (NRI); 94.0%, 89.1% (OC). The same pattern was observed for the composite measures of efficacy. 194 (45.0%) pts achieved MDA at Wk 16; of those, 85.6% (NRI) and 90.7% (OC) maintained their response at Wk 52. A high proportion of Wk 16 responders also maintained their response at Wk 52 for VLDA, DAPSA REM+LDA and DAPSA REM (Figure 1). To Wk 52, 555/702 (79.1%) pts reported ≥1 TEAE whilst receiving BKZ; 46 (6.6%) reported serious TEAEs. Conclusion With BKZ treatment, a high proportion of Wk 16 responders maintained robust efficacy responses to Wk 52, including across joint, skin and composite efficacy outcomes. The safety profile of BKZ was consistent with previous reports [2,3]. References [1]Boehncke WH. Am J Clin Dermatol 2013;14:377–88; [2]McInnes IB. Lancet 2022; DOI: 10.1016/S0140-6736(22)02302-9; [3]Merola JF. Lancet 2022; DOI: 10.1016/S0140-6736(22)02303-0; [4]Ritchlin C. Arthritis Rheumatol 2022;74(suppl 9). Acknowledgements This study was funded by UCB Pharma. Medical writing support was provided by Costello Medical, funded by UCB Pharma. Disclosure of Interests William Tillett Speakers bureau: AbbVie, Amgen, Celgene, Eli Lilly, GSK, Janssen, MSD, Novartis, Ovo Pharma, Pfizer and UCB Pharma, Consultant of: AbbVie, Amgen, Celgene, Eli Lilly, GSK, Janssen, MSD, Novartis, Ovo Pharma, Pfizer and UCB Pharma, Grant/research support from: AbbVie, Amgen, Celgene, Eli Lilly, GSK, Janssen, MSD, Novartis, Ovo Pharma, Pfizer and UCB Pharma, Joseph F. Merola Consultant of: AbbVie, Amgen, Biogen, BMS, Dermavant, Eli Lilly, Janssen, LEO Pharma, Pfizer, Novartis, Regeneron, Sanofi, Sun Pharma and UCB Pharma, Grant/research support from: AbbVie, Amgen, Biogen, BMS, Dermavant, Eli Lilly, Janssen, LEO Pharma, Pfizer, Novartis, Regeneron, Sanofi, Sun Pharma and UCB Pharma, Yoshiya Tanaka Speakers bureau: Speaking fees and/or honoraria from AbbVie, AstraZeneca, BMS, Boehringer Ingelheim, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Gilead, GSK, Mitsubishi Tanabe and Pfizer, Grant/research support from: AbbVie, Asahi-Kasei, Boehringer Ingelheim, Chugai, Daiichi-Sankyo, Eisai and Takeda, Ennio Giulio Favalli Speakers bureau: AbbVie, BMS, Celltrion, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer and UCB Pharma, Consultant of: AbbVie, BMS, Celltrion, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer and UCB Pharma, Dennis McGonagle Speakers bureau: AbbVie, Celgene, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Consultant of: Consulting fees and honoraria from AbbVie, Celgene, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie, Celgene, Janssen, Merck, Novartis and Pfizer, Jessica A. Walsh Consultant of: AbbVie, Amgen, Eli Lilly, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie, Amgen, Eli Lilly, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Diamant Thaçi Speakers bureau: AbbVie, Almirall, Amgen, Biogen, BMS, Boehringer Ingelheim, Celltrion, Eli Lilly, Galapagos, Janssen, LEO Pharma, Novartis, Pfizer, Regeneron, Samsung, Sanofi Genzyme and UCB Pharma, Consultant of: AbbVie, Almirall, Amgen, Biogen, BMS, Boehringer Ingelheim, Celltrion, Eli Lilly, Galapagos, Janssen, LEO Pharma, Novartis, Pfizer, Regeneron, Samsung, Sanofi Genzyme and UCB Pharma, Grant/research support from: LEO Pharma and Novartis, Barbara Ink Shareholder of: AbbVie, GSK and UCB Pharma, Employee of: UCB Pharma, Rajan Bajracharya Shareholder of: UCB Pharma, Employee of: UCB Pharma, Vanessa Taieb Employee of: UCB Pharma, Christopher T. Ritchlin Consultant of: Amgen, AbbVie, Eli Lilly, Gilead, Janssen, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie.