Clinical results for tocilizumab over one year in the clinical setting as assessed by CDAI (clinical disease activity index): CRP at week 12 and MMP-3 at week 24 are predictive factors for CDAI

To investigate the clinical results of 1 year tocilizumab (TCZ) treatment of rheumatoid arthritis patients in clinical practice by using the clinical disease activity index (CDAI). Thirty-one patients with inadequate response to DMARDs, including methotrexate (MTX), or TNF inhibitors received TCZ (8 mg every 4 weeks). The clinical responses were measured using the 28-joint disease activity score (DAS28-ESR) and CDAI. Matrix metalloproteinase-3 (MMP-3) was assessed as a serological biomarker. Mean baseline DAS28-ESR was 5.96, decreasing to 2.89 at week 52 with a remission rate (DAS28-ESR < 2.6) of 35.5%. Mean baseline CDAI was 28.4, decreasing to 10.2 at week 52 with a remission rate (CDAI ≤ 2.8) of 22.6%. Of patients whose CRP levels had fallen to below the limit of detection by week 12, 65.2% achieved remission or low disease activity as assessed by CDAI at week 52. Median baseline MMP-3 level was 165.7 ng/mL, decreasing to 79.5 ng/mL at week 52. A positive correlation was seen between CDAI at week 52 and MMP-3 level from week 12 onward. About 50% of the patients treated with TCZ in clinical practice achieved a low disease activity level at week 52 as assessed by CDAI, which does not include acute-phase proteins. Our results suggested that CRP levels falling to below the limit of detection by week 12 and MMP-3 ≤ 80.6 ng/mL at week 24 could predict low disease activity or remission at week 52 as assessed by CDAI.