SAT0671 SEROCONVERSION OF AUTOANTIBODIES TO UH-RA.21 PEPTIDE IS ASSOCIATED WITH CDAI REMISSION IN RHEUMATOID ARTHRITIS PATIENTS OF THE CARERA COHORT
Authors: Silke Loyens, Patrick Vandormael, Liesbeth De Winter, Veerle Stouten, Piet Geusens, Patrick Verschueren, Veerle Somers
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Autoantibodies are present in the majority of rheumatoid arthritis (RA) patients and are used clinically as diagnostic serum biomarkers. Insight in their role in prediction of therapy response and disease progression would provide a useful tool for patient stratification and personalized selection of a suitable treatment. In a previous pilot experiment, autoantibody levels to the University of Hasselt (UH) peptide UH-RA.21 have been correlated with response to DMARD treatment. In patients continuing the same DMARD during a 17 month follow-up period, which was taken as a proxy for treatment success, persistently positive anti-RA.21 antibody levels showed an overall decrease in titers (p=0.0334). <h3>Objectives:</h3> Our aim is to determine the association between autoantibodies to the UH-RA.21 peptide and disease remission in early RA patients from the CareRA cohort. <h3>Methods:</h3> In the CareRA trial, different COBRA treatment regimens consisting of synthetic DMARDs combined with a step-down glucocorticoid treatment, have been studied. Disease remission was defined as a DAS28CRP&lt;2.6, CDAI&lt;2.8 or SDAI&lt;3.3. Custom peptide enzyme-linked immunosorbent assays were used to screen for the presence of antibodies to the UH-RA.21 peptide in serum samples of the CareRA cohort. Cut-off for seropositivity was defined by 2 x SD above the mean antibody level of the healthy control group. Antibody reactivity to UH-RA.21 was evaluated in baseline samples, collected before the start of treatment, of 223 early RA patients from the CareRA cohort. In patients that were positive for anti-UH-RA.21 antibodies at baseline, follow-up samples collected 16, 40, 52 and 104 weeks after the initiation of treatment were tested. <h3>Results:</h3> Antibodies to UH-RA.21 were found in 21% (47/223) of the baseline samples from the CareRA cohort. Compared to baseline levels, combination therapy induced a 50% reduction of anti-UH-RA.21 antibody levels in 30% of patients after 16 weeks and in 47% of patients after 52 weeks. Seroconversion was observed in 16% (7/44) of patients after 16 weeks and 30% (10/34) after 52 weeks. Seroconversion was not correlated with remission according to the DAS28CRP or SDAI remission indices. However, of those patients which were UH-RA.21 positive at baseline, more seroconversion occurred in patients reaching remission (5/14, 36%) than in patients remaining in active disease (2/30, 7%), according to CDAI remission criteria (p=0.025). <h3>Conclusion:</h3> A COBRA therapy induces a rapid decrease in anti-UH-RA.21 autoantibody levels in many patients. Moreover, early anti-UH-RA.21 seroconversion is associated with CDAI remission. <h3>Disclosure of Interests:</h3> Silke Loyens: None declared, Patrick Vandormael: None declared, Liesbeth De Winter: None declared, Veerle Stouten: None declared, Piet Geusens Grant/research support from: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Grant/research support from: Pfizer, Abbott, Lilly, Amgen, MSD, Will, Bio Minerals and Roche, Consultant for: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Speakers bureau: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Speakers bureau: Pfizer, Abbott, Lilly, Amgen, MSD, Will, Bio Minerals and Roche, Patrick Verschueren Grant/research support from: Unrestricted Pfizer Grant for Early RA research, Veerle Somers Grant/research support from: Research support from Bristol Myers-Squibb