POS0896 PREDICTORS OF RESPONSE IN PATIENTS WITH NON-RADIOGRAPHIC AXIAL SPONDYLOARTHRITIS RECEIVING CERTOLIZUMAB PEGOL IN THE C-AXSPAND STUDY
Authors: Maksymowych W. P. , Kumke T. , Auteri S. , Hoepken B. , Bauer L. , Rudwaleit M. 
Published: May 2021

Background:Identification of predictive clinical factors of long-term treatment response in non-radiographic axial spondyloarthritis (nr-axSpA) may contribute to improved management of patients with this chronic disease. Certolizumab pegol (CZP) is currently the only FDA-approved tumour necrosis factor inhibitor (TNFi) for treatment of nr-axSpA.1Objectives:To identify whether any demographic or baseline characteristics of nr-axSpA patients from the C-axSpAnd study2 are predictive of achieving a clinical response after 1 year of CZP treatment.Methods:C-axSpAnd (NCT02552212) was a phase 3, interventional multicentre study including a 52-week double-blind, placebo-controlled period. Full study design is reported elsewhere.2 Multivariate stepwise logistic regression analysis was used to identify predictors of response for the primary efficacy variable (Ankylosing Spondylitis Disease Activity Score – major improvement [ASDAS-MI] at Week 52) and the main secondary efficacy variable (Assessment of SpondyloArthritis international Society 40% [ASAS40] at Week 52) in patients randomised to CZP 200 mg every 2 weeks (Q2W). Predictive factors used in the model included demographic and baseline characteristics, and clinical outcomes at Week 12. A p value ≤0.05 was required for forward selection into the model and p=0.1 for backward elimination from the model. Non-responder imputation was used to account for missing data or values collected after switching to open-label treatment. A sensitivity analysis was conducted to account for patients who had changes in their non-biologic background medication during the 52-week placebo-controlled period.Results:A total of 159/317 patients were randomised to CZP 200 mg Q2W and 158/317 to placebo. Predictive factors identified for Week 52 ASDAS-MI in the CZP-treated patients included being positive for both presence of sacroiliitis on MRI (MRI+) and human leukocyte antigen (HLA)-B27 (HLA-B27+), having a higher Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) at baseline, and having a larger Week 12 improvement in ASDAS (Figure 1A). For ASAS40 response, MRI+/HLA-B27+ was also identified as a predictor of Week 52 response, along with a lower baseline Bath AS Metrology Index (BASMI) and larger Week 12 improvements in Patient Global Assessment of Disease Activity (PtGADA) and AS Quality of Life (ASQoL; Figure 1B). Sensitivity analysis identified the same predictors for ASDAS-MI and ASAS40, with the exception of change from baseline in PtGADA as a predictor of ASAS40. Sensitivity analysis also identified achievement of Week 12 ASAS40 as a predictor of Week 52 ASAS40. In placebo-treated patients, no meaningful predictors of response at Week 52 were identified.Conclusion:Presence of sacroiliitis on MRI and HLA-B27 positivity were identified as consistent predictors of Week 52 response (ASDAS-MI and ASAS40) in nr-axSpA patients treated with CZP. To our knowledge, this is the first report from an interventional 52-week placebo-controlled study in nr-axSpA to identify objective clinical features, particularly the presence of sacroiliac joint inflammation, as being predictive of response.References:[1]Ashrafi M. Curr Opin Rheumatol 2020;32:321–9.[2]Deodhar A. Arthritis Rheumatol 2019;71:1101–11.Acknowledgements:This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.Disclosure of Interests:Walter P Maksymowych Speakers bureau: AbbVie, Janssen, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, BMS, Boehringer, Eli Lilly, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, Novartis, Pfizer, Thomas Kumke Shareholder of: UCB Pharma, Employee of: UCB Pharma, Simone Auteri Shareholder of: UCB Pharma, Employee of: UCB Pharma, Bengt Hoepken Shareholder of: UCB Pharma, Employee of: UCB Pharma, Lars Bauer Shareholder of: UCB Pharma, Employee of: UCB Pharma, Martin Rudwaleit Speakers bureau: AbbVie, Eli Lilly, Novartis, UCB Pharma, Consultant of: AbbVie, Celgene, Eli Lilly, Janssen, Novartis, UCB Pharma