Background: Interleukin-17A inhibitors (IL-17Ai) and tumour necrosis factor inhibitors (TNFi) are available for treatment of axial spondyloarthritis (axSpA). Bio-naïve patients generally respond better to the first TNFi compared to those who are TNFi-experienced. However, real-world data on the effectiveness of IL-17Ai used as a first line treatment vs a second or third line treatment, i.e. after TNFi exposure, are sparse.

Objectives: In axSpA patients initiating a first IL-17Ai treatment in routine care and stratified by prior exposure to TNFi (0/1/2), we aimed to a) describe the baseline demographics, clinical and disease activity characteristics, b) assess and compare 6-month composite scores of low disease activity (LDA) and response rates, and c) assess and compare 12-month retention rates.

Methods: The study was conducted within the European Spondyloarthritis (EuroSpA) Research Collaboration Network. Patients with axSpA who initiated a first IL-17Ai between 2018 and 2022 were included from 13 European registries. Logistic regression analyses were employed to compare 6-month LDA (Ankylosing Spondylitis Disease Activity Score using C-reactive protein (ASDAS-CRP) <2.1 and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) <4) and response rates (ASAS 40 response and ASDAS-CRP Clinically Important Improvement (CII), i.e delta-ASDAS-CRP ≥1.1). Log-rank tests and cox regression analyses were performed to compare 12-month IL-17Ai retention. All analyses were adjusted for age, sex, registry, time since diagnosis, and ASDAS-CRP at treatment start (baseline). To account for missing baseline data, multivariate imputation by chained equations were employed.

Results: A total of 2265 axSpA patients were included, with 799/787/679 having previously received 0/1/2 TNFi, respectively. At baseline, bio-naïve patients were more likely to be male (64% / 53%/49% for 0/1/2 previously TNFi-exposed) and HLA-B27 positive (81%/78%/74%). Additionally, bio-naïve patients had higher disease activity according to BASDAI (6.4/5.2/5.8) and ASDAS-CRP (4.2/3.3/3.5), and a higher proportion of them received concomitant csDMARDs (29%/21%/19%).

At 6 months, bio-naïve patients demonstrated numerically higher rates of LDA and response across all outcomes compared to TNFi-experienced patients. Similarly, after adjusting for confounders, significantly better responses were found for bio-naïve compared to TNFi-experienced patients for all outcomes (Table 1).

The overall 12-month IL-17Ai retention rate was 79.5%. Notably, the 12-month IL-17Ai retention decreased with an increased number of previous TNFi (85.2%/77.9%/74.6%, for 0/1/2 previously TNFi-exposed, p<0.001), with statistically significant differences between bio-naïve and TNFi-experienced patients (Table 1).

Conclusion: This large real-world study showed overall high one-year retention of IL-17Ai treatment in axSpA. Notably, bio-naïve patients, despite exhibiting higher baseline disease activity, demonstrated superior 6-month LDA and response rates as well as higher 12-month retention compared to TNFi-experienced patients.

Acknowledgements: The EuroSpA collaboration is supported by Novartis and UCB. This EuroSpA study was financially supported by UCB. UCB had no influence on the data collection, statistical analyses, abstract preparation, or decision to submit.

Disclosure of Interests: Marion Pons Novartis (paid to the employer), Stylianos Georgiadis Novartis (paid to the employer), Merete Lund Hetland Pfizer, Medac, Sandoz (no personal income, institution), Advisory Board Abbvie (No personal income, paid to institution). Prev. chaired the steering committee of the Danish Rheumatology Quality Registry (DANBIO, DRQ), which receives public funding from the hospital owners and funding from pharmaceutical companies., Research grants (institution) from Abbvie, Biogen, BMS, Celltrion, Eli Lilly, Janssen Biologics B.V, Lundbeck Fonden, MSD, Medac, Pfizer, Roche, Samsung Biopies, Sandoz, Novartis, Nordforsk, Louise Linde Research grant from Novartis, Mehrdad Shoae Kazemi Novartis (paid to the employer), Simon Horskjær Rasmussen Novartis (paid to the employer), Anne Gitte Loft Speaking fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, UCB, Consulting fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, UCB, Research grant from Novartis, Brigitte Michelsen Consulting fees from Novartis, Research grant from Novartis (paid to employer). Centre for treatment of Rheumatic and Musculoskeletal Diseases (REMEDY) is funded as a Centre for Clinical Treatment Research by The Research Council of Norway (project 328657), Daniela Di Giuseppe: None declared, Gary J. Macfarlane Research grant from GSK, Gareth T. Jones Speaker fee from Janssen., Research grants (paid to employer) from AbbVie, Pfizer, UCB, Amgen, GSK., Karin Laas Abbvie, Johnson and Johnson, Novartis, Pfizer, Sigrid Vorobjov: None declared, Isabel Castrejon Speaker fees from BMS, Eli-Lilly, Galapagos, Gilead, Janssen, Novartis, MSD, Pfizer, GSK, Consultancy fees from BMS, Eli-Lilly, Galapagos, Gilead, Janssen, Novartis, MSD, Pfizer, GSK, Fernando Sánchez-Alonso: None declared, Ziga Rotar Abbvie, Amgen, Novartis, MSD, Medis, Biogen, Eli Lilly, Pfizer, Sanofi, Lek, Janssen, Abbvie, Novartis, Eli Lilly, Pfizer, Janssen, SOBI, Swixx BioPharma, AstraZeneca, Katja Perdan Pirkmajer Abbvie, Novartis, MSD, Medis, Eli Lilly, Pfizer, Lek, Janssen, Abbvie, Novartis, Medis, Eli Lilly, Pfize, Boehringer Ingelheim, Jana Baranová: None declared, Bente Glintborg Research grants from Pfizer, Abbvie, BMS, Sandoz, Adrian Ciurea: None declared, Miguel Bernardes: None declared, Paula Valente: None declared, Bjorn Gudbjornsson Speaking fees from Novartis and Nordic-Pharma, Consulting fees from Novartis, Gerdur Grondal: None declared, Catalin Codreanu Speaker fees from AbbVie, Amgen, Boehringer Ingelheim, Ewopharma, Lilly, Novartis, Pfizer, Consulting fees from AbbVie, Amgen, Boehringer Ingelheim, Ewopharma, Lilly, Novartis, Pfizer, Corina Mogosan Speaker fees from AbbVie, Boehringer Ingelheim, Ewopharma, Lilly, Novartis, Pfizer, Sella Aarrestad Provan Boehringer Ingelheim, Boehringer Ingelheim, Florenzo Iannone Speaking fees from Abbvie, Amgen, AstraZeneca, BMS, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB, Consulting fees from Abbvie, Amgen, AstraZeneca, BMS, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB, Research grant from BMS, Galapagos, Pfizer, Roberto F. Caporali Speaking fees from Abbvie, Amgen, AstraZeneca, BMS, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB, Consulting fees from Abbvie, Amgen, AstraZeneca, BMS, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB, Johan K Wallman Speaker fees from AbbVie, Amgen, Research support from AbbVie, Amgen, Eli Lilly, Novartis, Pfizer, Vappu Rantalaiho Novartis, Viatris, Pfizer, Ritva Peltomaa Abbvie, Boehringer,Celltrion,Fresenius, Lilly, UCB, Gunnstein Bakland: None declared, Ladislav Šenolt: None declared, Mikkel Østergaard Speaker and/or consultancy fees from Abbvie, BMS, Boehringer-Ingelheim, Celgene, Eli-Lilly, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi, UCB, Speaker and/or consultancy fees from Abbvie, BMS, Boehringer-Ingelheim, Celgene, Eli-Lilly, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi, UCB, Research grants from Abbvie, BMS, Merck, Novartis and UCB, Lykke Midtbøll Ørnbjerg Research grant from Novartis.