Background and Objectives Biological therapy has dramatically improved the treatment of rheumatoid arthritis (RA). One-third of patients however show a lack of clinical response to this treatment. The use of robust predictive markers of response to identify individuals who are likely to respond to biological treatments may provide guidance in optimising treatment strategies and lead to lower costs. The ability of MRP8/14 serum complexes, a major granulocyte and monocyte protein associated with inflammation in patients with RA, was tested to differentiate between responders and non-responders to various biological treatments and to monitor disease activity in these RA patients.
Materials and Methods 170 RA patients were treated with adalimumab, infliximab or rituximab and were categorised into responders (n = 123) and non-responders (n = 47) according to the European League Against Rheumatism (EULAR) response criteria. Serum concentrations of MRP8/14 complexes were measured at baseline, week 4 and week 16 and divided in low and high MRP8/14 serum complexes level groups based on the median level for each treatment group. Non-parametric tests were used to analyse the data.
Results Before initiation of adalimumab, infliximab or rituximab treatment, responders showed significantly higher levels of MRP8/14 serum complexes compared to non-responders. (p = 0.010, p = 0.001 and p < 0.001, respectively). Logistic regression analysis showed that having a high level of MRP8/14 serum complexes at baseline increased the odds of being a responder by a factor of 3.3 till 55. MRP8/14 serum complexes levels decreased after 4 weeks with respectively 46% and 60% (respectively median delta changes ∆400; IQ 160–895 and 840; IQ170–1170) and 16 weeks with 61% and 68% (∆730; IQ220–1120 and ∆970; IQ530–1830) of treatment in responders to adalimumab and infliximab, while MRP8/14 serum complexes levels were stable in non-responders. In patients treated with rituximab, MRP8/14 serum complexes decreased with 61% (∆1670; IQ959.5–3520) after 16 weeks in responders (p = 0.0005) and increased with 94% (∆960; IQ405–1135) after 16 weeks in non-responders to treatment (p = 0.0039).
Conclusions MRP8/14 serum complexes can be used as a biomarker predictive of the response to biological therapy in RA patients.