To identify a biomarker for prediction of the response to infliximab (IFX) in patients with rheumatoid arthritis (RA), we focused on a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) that seems to play a key role in aggrecan degradation in cartilage.
Seventy-three randomly selected patients with active RA were treated with IFX. Peripheral blood samples were collected at baseline and ADAMTS5 messenger RNA (mRNA) was quantified using real-time polymerase chain reaction.
Baseline ADAMTS5 mRNA levels in the good responder group were significantly lower (1.84 +/- 1.56; p = 0.0408) than those in the moderate and nonresponder groups (2.54 +/- 1.70) at 38 weeks of treatment with IFX. The 28-joint count Disease Activity Score (DAS28) at 38 weeks of treatment was significantly lower in the low ADAMTS5 group (2.30 +/- 1.28; p = 0.0038) than in the high ADAMTS5 group (3.90 +/- 1.61). The percentage reduction of the DAS28 was significantly higher in the low ADAMTS5 group (52.5% +/- 28.8%; p = 0.0156) than in the high ADAMTS5 group (29.4% +/- 27.2%). Further, the Delta Health Assessment Questionnaire (DeltaHAQ) score, an estimate of the improvement in the HAQ score, at 38 weeks of treatment was significantly higher in the low ADAMTS5 group (1.18 +/- 0.60; p = 0.0102) than in the high ADAMTS5 group (0.21 +/- 0.78). The positive predictive value of a low baseline ADAMTS5 level for predicting good response and remission (DAS28 < 2.6 at 38 weeks) was 90.0% and 70.0%, respectively.
The baseline ADAMTS5 mRNA level is a candidate biomarker for prediction of the response to IFX in patients with RA.