[Clinical significance of serum cartilage biomarkers in the treatment of rheumatoid arthritis with biological therapy].

With the current use of biologics in RA, numerous patients can achieve clinical remission, however structural joint damage occurs in substantial numbers of the patients. The present study assessed cartilage damage during 54-week anti-TNF therapy, using serum cartilage markers, and potential advantages of these markers were evaluated. Levels of serum hyaluronan decreased with decreasing levels of CRP in both early and established RA, whereas indicator of type II collagen synthesis/degradation, C2C/CP II decreased only in early RA group. Levels of COMP and keratin sulfate significantly decreased and increased compared to baseline, respectively, by week 54 in established RA. Strikingly, C2C/CP II levels were universally improved in early RA, regardless of CRP levels or EULAR response grade. In contrast, C2C/CP II levels universally worsened in established RA, even though patients achieved good response. As a role of surrogate marker reflecting therapeutic efficacy of biological therapy, C2C/CP II appears particularly useful for determining the degree of ongoing structural joint deterioration, which is dissociated from clinical assessment of disease activity in RA.