Baseline serum RANKL levels may serve to predict remission in rheumatoid arthritis patients treated with TNF antagonists

Aims: The objective of this study was to investigate whether baseline receptor activator for nuclear factor kappaB ligand ( RANKL) and osteoprotegerin ( OPG) serum ( s) levels can predict the therapeutic response to TNF antagonists ( a-TNF). Methods: We studied 75 rheumatoid arthritis patients ( 81% female) with a longstanding refractory disease. The variables of disease activity, physical function and sRANKL and sOPG levels were determined before and after both 12-14 and 28 30 weeks of a-TNF therapy ( 65 adalimumab, 10 infliximab). Remission was defined by a 28 joint count disease activity score ( DAS28) <= 2.6 and clinical response by a reduction in DAS28 >= 1.2 at both 3- and 7-month follow-up visits. Results: In most patients, disease activity was severe, as reflected by a baseline DAS28 score of 5.9 +/- 1 ( mean +/- SD), an HAQ of 1.6 ( 1.1 to 2.1) ( median ( interquartile range ( IQR))) and a CRP 15 mg/l ( IQR: 9 to 24). The sRANKL levels and RANKL/ OPG ratio in patients that achieved remission were significantly lower at baseline than in the remaining patients at both 3 and 7 months of follow-up. The sOPG levels correlated with the HAQ and the physician's disease assessment and diminished significantly after a-TNF treatment. However, no significant association was detected between the therapeutic response profile and sOPG levels. Conclusions: These data suggest that in patients receiving a-TNF treatment, lower serum levels of RANKL and RANKL/ OPG ratio may serve to predict remission.