Interleukin-6 (IL-6) inhibition with tocilizumab (TCZ) plus methotrexate(Drug information on methotrexate) (MTX) retards joint damage progression independently of its impact on disease activity in patients with rheumatoid arthritis (RA). Similar effects have been reported only for tumor necrosis factor (TNF) inhibitors, indicating that the effects of IL-6 inhibition on progression of joint damage in RA are among the most profound currently attainable.
Smolen and associates at the Medical University of Vienna used a random 90% sample of data from the TociLIzumab Safety and THE Prevention of Structural Joint Damage (LITHE) study to compare the addition of placebo with the addition of TCZ every 4 weeks. They correlated baseline and 1-year values of clinical and serological variables with changes to 1 year of the total Genant-modified Sharp score (TGSS) using a Spearman test. Also, the progression of TGSS, erosion, and joint-space narrowing scores in groups that had low and high disease activity were compared for placebo and TCZ.
The change of TGSS was less in patients who received TCZ than in those who received placebo. In the latter patients, the correlation with TGSS change was significant for baseline scores of the Simplified Disease Activity Index (SDAI) and swollen joint count 28, with similar trends for C-reactive protein level. Similar correlations were seen for the SDAI, clinical disease activity index, and disease activity score 28 at 1 year, with radiographic changes during that year. None of the baseline or 1-year variables showed significant correlation with radiographic changes in patients who received TCZ plus MTX, suggesting a disassociation of the link between disease activity and damage by TCZ.
For patients in remission or with low disease activity, the progression of TGSS, erosion, and joint-space narrowing was similar among treatment groups; for those with moderate or high disease activity, progression was significantly greater in placebo-treated patients. The findings were reported in Annals of the Rheumatic Diseases.