Baseline autoantibodies preferentially impact abatacept efficacy in patients with rheumatoid arthritis who are biologic naïve: 6-month results from a real-world, international, prospective study

Objectives: To determine the impact of baseline rheumatoid factor (RF) and anticyclic citrullinated peptide (anti-CCP) status on the clinical efficacy of intravenous abatacept in biologic-naïve patients with rheumatoid arthritis (RA) enrolled in the real-world ACTION study. Methods: Clinical outcomes (European League Against Rheumatism (EULAR) response, mean Clinical Disease Activity Index (CDAI) and Boolean remission) at 6 months were compared by baseline RF and anti-CCP status. Results: Of 672 biologic-naïve patients, RF status was reported in 577 (86%) (412 (71%) positive) and anti- CCP status in 552 (82%) (364 (66%) positive); of 511 patients for whom data were available, 308/511 (60%) were double positive and 127/511 (25%) were double negative. Clinical outcomes were improved with RFpositive or anti-CCP-positive versus RF-negative/anti- CCP-negative status - good or moderate EULAR response: RF: 84.6 vs 72.9%, p=0.012; anti-CCP: 85.2 vs 74.2%, p=0.015; mean CDAI (calculated): RF: 10.8 vs 15.3, p<0.001; anti-CCP: 10.9 vs 14.3, p=0.002; and Boolean remission: RF: 13.3 vs 4.0%, p=0.008; anti-CCP: 12.5 vs 6.3%, p=0.096. Clinical outcomes were also improved with single or double RF-positive/ anti-CCP-positive versus double-negative status. Conclusions: In biologic-naïve patients with RA, RF-positive and/or anti-CCP-positive status is associated with greater efficacy of intravenous abatacept than seronegative status.