Background ADA is effective and safe drug for the treatment of RA. Application of ADA can be accompanied by formation anti-adalimumab antibody (anti-ADA Ab) influencing on efficiency of therapy and the development of adverse events
Objectives To evaluated the correlation of serum levels of ADA and anti-ADA Ab in relation to clinical response in patients (pts) with early RA
Methods Serum levels of ADA (μg/ml) and anti-ADA Ab (positive/negative result) was determined by ELISA in 25 pts with early RA (15 women, mean age – 54,0; 47,0-58,0 years, mean disease duration - 8,0; 5,0-25,0 months, mean DAS 28 – 5,8; 4,9-7,5, SDAI 34,3; 22,8-54,2, CDAI 32,0; 21,7-48,4) baseline and then after 12 and 24 weeks of treatment. All patients received disease-modifying antirheumatic drugs (DMARDs) (100%>methotrexate) and ADA 40mg every 2 weeks. For all patients the ADA was the first biologic
Results On the 12-th week of therapy values [Me; interquartile range] DAS 28 were 3,5 (3,2-4,4); SDAI-13,0 (7,0-16,6); CDAI - 10,8 (7,0-16, 0), 6 pts achieved a good EULAR response, 14- moderate response. On the 24-th week of treatment the value DAS 28 were 3,5 (3,1-4,4), SDAI-11,7 (7,4-17,5) and CDAI - 10,5 (6,2-16, 3), a good response was noted at 7 patients, moderate response - at 9 pts.
The pts was distributed in two groups from serum levels of ADA: <3,0 (the first group n=7) and ≥3,0 (second group n=13). There were no differences between the groups on disease activity, level of acute-phase reactants by the 12th week of therapy (p>0,05). Higher disease activity and also the level of acute-phase reactants were marked out among pts of the first group (DAS 28 – 4,5; 3,3-4,9, ESR – 44; 18-57 mm/h, CRP -10,1; 4,9-34,5 mg/ml) compared with pts of the second group (3,5; 2,9-3,9, 15,0; 6,0-17,0 mm/h, 1,9; 0,75-6,7 mg/ml, respectively, p<0,05) by the 24th week of therapy. Also on the 24th week negative correlation was found with level of ADA and DAS 28 (r= -0,46; p=0,04), CRP (r= -0,54; p=0,02) and ESR (r= -0,5; p=0,02).
Anti-ADA Ab was found in 3 (12,5%) pts at week 12 and in 2 (10%) pts at week 24. By 24th week of treatment at 100% of pts with presence of anti-ADA Ab was absence of clinical effect (ΔDAS28 = -1,36; -3,1-0,4). In the group of pts without anti-ADA Ab we found fewer of “no respondents” (11%) and identified positive dynamics DAS 28 (ΔDAS28=2,5; 1,66-2,9) (p<0,05)
Conclusions Low drug level (<3,0 μg/ml) in serum is associated with a high clinical and laboratory disease activity at pts with early RA receiving the ADA therapy. By 12-24 weeks of ADA therapy anti-ADA Ab is found in 10-12,5% of pts, it's formation is accompanied of decrease in efficacy of therapy
Disclosure of Interest None declared