Background Clinical response to biologics varies widely between individuals with rheumatoid arthritis (RA). To date, there are few, and in some cases, conflicting results in the personalized approach of patients with RA treated with abatacept. Only the seropositive subphenotype (anti-cyclic citrullinated peptide, CCP) was validated in several populations, including a real-life registry (ORA) , and non-inferiority trial (AMPLE) .
Objectives To assess whether baseline anti-CCP3 antibody status and concentration correlated with drug survival of subcutaneous (SC) abatacept among patients with RA in a real-world setting.
Methods This was a prospective study in which well-characterized patients with RA (by 1987 ACR criteria) were included from April 2014 to December 2016. Patients were evaluated at a single rheumatology outpatient center in Bogotá, Colombia. Baseline anti-CCP3 antibody status (positive/negative) and concentration were determined using an anti-CCP3 IgG ELISA (INOVA Diagnostics). Patients with a baseline anti-CCP3 IgG concentration of ≥20 U were considered to be positive and were further divided into equal quartiles according to concentration [Q1–Q4 (highest concentration)]. The Cox proportional hazards regression model was used to test if there were any differences in drug survival curves according to baseline anti-CCP3 antibody status and concentration. The test was performed by the coxph function of the “survival” R package .
Results A total of 129 patients were included. Baseline characteristics: female gender 86%, mean age 52±13 years, median disease duration 10 (IQR 11) years, and erosions 35%. Treatment background was as follows: biologic-naïve (n=54), switched from IV to SC abatacept administration (n=24), and inadequate response to at least 1 biologic disease-modifying antirheumatic drug (n=51). Forty-three patients (33%) discontinued treatment. The most frequent reasons for drug suspension were loss of efficacy. Rheumatoid Factor and anti-CCP3 was positive in 94%, and 89%, respectively. Median titre of anti-CCP3 was 248 U (IQR 352), and number of patients in each quartile group were Q1 (22–122)=21; Q2 (123–248)=20; Q3 (249–475)=19; Q4 (476–1544)=19. According to Cox proportional hazards regression model (Fig.1), there were significant differences between survival curves for Q1 (HR 0.1; 0.02–0.60 95% IC; p=0.011), Q2 (HR 0.2; 0.06–0.94 95% IC; p=0.041), and Q3 (HR 0.2; 0.04–0.85 95% IC; p=0.030), compared to negative group at month 32.
Conclusions Baseline anti-CCP3 positivity was associated with a better response for SC abatacept in a real-world setting. Patients with lowest baseline anti-CCP3 antibody concentrations had better drug survival than patients with higher concentrations. Our results highlight the importance of identification of factors associated with response to biologics in order to optimize treatment and reduce costs.
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Disclosure of Interest None declared