medwireNews: Patients with rheumatoid arthritis (RA) who initiate tocilizumab as their first biologic therapy after failure of conventional synthetic disease-modifying antirheumatic drugs have better disease outcomes than those who initiate tumor necrosis factor inhibitors (TNFi), observational study data suggest.
For the ACT-iON study, conducted across 158 sites in 26 countries, 1216 patients with moderate-to-severe RA were prescribed the interleukin-6 receptor-α inhibitor tocilizumab or TNFi according to the preference of the treating physician and then prospectively observed in routine clinical practice for 52 weeks.
Tocilizumab was prescribed to 35%, with the remaining 65% receiving TNFi as their first biologic therapy. And although the groups were generally well-matched for baseline demographics, disease characteristics, and concomitant therapies, RA duration was shorter and disease activity and corticosteroid use were higher in tocilizumab patients.
Ernest Choy (Cardiff University, UK) and colleagues report in Arthritis Care and Research that patients receiving tocilizumab had significantly greater improvements in Disease Activity Score based on 28 joints–erythrocyte sedimentation rate (DAS28-ESR) than those receiving TNFi, with adjusted mean differences of −0.831 at week 24 and –0.910 at week 52.
Decreases in Clinical Disease Activity Index (CDAI) and Simplified DAI (SDAI) from baseline to weeks 24 and 52 were also significantly greater in patients treated with tocilizumab than those treated with TNFi.
In line with this, significantly higher proportions of tocilizumab- than TNFi-treated patients achieved remission according to CDAI criteria (CDAI ≤2.8) at weeks 24 (22.4 vs 14.6%) and 52 (27.8 vs 18.3%). But the researchers note that for SDAI remission (SDAI ≤3.3), which includes calculation of C-reactive protein, the difference between tocilizumab and TNFi was only significant at week 52 (32.4 vs 21.6%).
Choy et al also observed greater improvements in patient-reported outcomes for tocilizumab versus TNFi, with significantly greater decreases in Health Assessment Questionnaire–Disability Index and Functional Assessment of Chronic Illness Therapy–Fatigue scores reported by the former group at week 24.
In addition, patients receiving tocilizumab were less likely to have discontinued treatment by week 52, at 15%, compared with 27% of those receiving TNFi. Of these, fewer patients in the tocilizumab than in the TNFi group discontinued therapy because of lack of efficacy (23.8 vs 48.8%), whereas the proportion stopping due to adverse events was similar between the groups (38.1 and 40.1%, respectively).
Indeed, adverse events were generally reported at similar rates in both treatment groups, with infections being the most common, occurring in 20.8% and 25.9% of patients treated with tocilizumab and TNFi, respectively.
Discussing their findings, Choy and co-authors caution that they “should be interpreted with an understanding of the limitation of potential biases associated with observational studies.”
Although they add that analyses adjusting for potential response predictors, including propensity score–based matching, supported the key findings of their study.
By Laura Cowen
medwireNews is an independent medical news service provided by Springer Healthcare. © 2017 Springer Healthcare part of the Springer Nature group