FRI0119 What Intrinsic and Extrinsic Factors Affect the Developement of Anti-Drug Antibody to Innovator Infliximab and its Biosimilar CT-P13 in Rheumatoid Arthritis and Ankylosing Spondylitis: Table 1.

Background Infliximab, a chimeric anti-TNF antibody, is well known to potentially induce anti-drug-antibodies (ADA), which may result in loss of efficacy and cause side effects such as infusion reactions. However, it is not well known which factors affect ADA formation. Objectives A retrospective analysis for factors related to immunogenicity was performed using the data sets of two recent randomized controlled trials documenting biosimilarity between innovator infliximab (INX) and CT-P13 (PLANETRA and PLANETAS). Methods A total of 852 patients (602 patients with rheumatoid arthritis (RA) in PLANETRA and 250 patients with ankylosing spondylitis (AS) in PLANETAS) were treated with either 3mg/kg (RA) or 5mg/kg (AS) of CT-P13 or INX. ADA assessment was performed at weeks 14, 30 and 54. The determination of ADA utilized an electrochemiluminiscence assay (ECLA, MSD, Rockville, Maryland, USA). Age, gender and race as intrinsic factors and methotrexate (MTX) or glucocorticoid (GC) as extrinsic factors were analyzed with a logistic regression. Results The immunogenicity results were overall similar between CT-P13 and INX during the study period in both trials whilst there was a noticeable difference between patients with RA and AS (1). In PLANETRA, gender, race, GC and MTX did not impact on ADA positive rate but the impact of age was statistically significant (Table 1). In PLANETAS, none of age, gender, race or GC had impact on ADA positive rate (Table 1). The interactions between treatment and each factor showed that the effect of factors (age, gender, race, GC and MTX) on ADA development was not statistically different between CT-P13 and INX. Conclusions On the basis of similar immunogenicity between CT-P13 and INX in AS and RA patients, we only found age as an influencing factor in patients with RA. This finding may be related to the immunosenecence in the elderly. Furthermore, no influence by medication was detected: neither GC nor MTX seemed to have an impact on ADA formation in these two trials. References Jurgen Braun et al., Striking Discrepancy in the Development of Anti-Drug Antibodies (ADA) in Patients with Rheumatoid Arthritis (RA) and Ankylosing Spondylitis (AS) in Response to Infliximab (INF) and Its Biosimilar CT-P13, ACR 2014 Disclosure of Interest J. Braun Grant/research support from: CELLTRION, Inc., Consultant for: CELLTRION, Inc., Speakers bureau: CELLTRION, Inc., W. Park Grant/research support from: CELLTRION, Inc., Consultant for: CELLTRION, Inc., Speakers bureau: CELLTRION, Inc., D. H. Yoo Grant/research support from: CELLTRION, Inc., Consultant for: CELLTRION, Inc., Speakers bureau: CELLTRION, Inc., C. H. Suh Grant/research support from: CELLTRION, Inc., Consultant for: CELLTRION, Inc., S. C. Shim Grant/research support from: CELLTRION, Inc., Consultant for: CELLTRION, Inc., S. J. Lee Employee of: CELLTRION, Inc., S. Y. Lee Employee of: CELLTRION, Inc., J. H. Yun Employee of: CELLTRION, Inc., S. Y. Kim Employee of: CELLTRION, Inc., S. M. Lee Employee of: CELLTRION, Inc.