To evaluate whether the baseline presence of rheumatoid arthritis (RA)-associated biomarkers could define subgroups of patients that are more prone to show a spontaneous decrease of RA disease activity. In a previous placebo-controlled phase II trial that failed to show any superiority of the experimental compound versus placebo, a remarkable decrease of such disease activity was observed despite the lack of effective treatment.
A subgroup of 83 disease modifying antirheumatic drug-naive RA patients with disease duration < 3 years was analyzed. Rheumatoid factor (RF), anti-citrullinated protein/peptide antibodies (ACPA), and HLA shared epitope (SE) were determined at baseline.
RF-positive patients tended to have higher levels of disease activity at baseline compared to RF-negative patients [Disease Activity Score (DAS) 6.12 vs 5.65, p = 0.02 at screening], but the decrease in disease activity was similar in both subgroups (DAS -1.23 vs -1.07). In contrast, ACPA-positive patients showed similar baseline disease activity scores compared to ACPA-negative patients, but tended to show a smaller decrease of disease activity than patients without ACPA (Delta DAS -1.53 vs -0.79, p = 0.013). Presence of the HLA-SE seemed not to have any effect on the baseline DAS or on the spontaneous decrease of DAS.
The predictive value of baseline RA-associated biomarkers for spontaneous decrease of disease activity under placebo or ineffective treatment is limited. Yet the data analyzed here might be useful for the design of future placebo-controlled trials in RA.