Background In treatment of RA using TNF-inhibitors, switching to another treatment is recommended if a patient shows moderate or high disease activity (MDA, HDA) at 3 months (1). Meanwhile, dose-escalation of IFX was performed for patients with inadequate response to standard-dose treatment in clinical practice. Therefore, predicting the long-term efficacy of both standard and higher-dose of IFX therapy at 3 months is seemed to be extremely important.
Objectives The RISING study is a randomized double-blind clinical study of IFX therapy in MTX-refractory RA (2). Using data obtained in this study, we conducted post-hoc analysis to determine the probability of achieving REM or LDA at week 54 (w54) based on the disease activity at week 14 (w14) by using logistic regression analysis.
Methods In the RISING study, after patients received 3 mg/kg IFX infusion at weeks 0, 2, and 6, they were randomly assigned to three groups: 3, 6, or 10 mg/kg IFX, every 8 weeks from w14 to w46 in a double-blind manner (n=307). Disease activities (SDAI, DAS28-CRP) were evaluated at w14 and w54.
Results In each treatment group, disease activity at w14 closely correlated with that at w54 (p<0.0001). In the logistic regression analysis, median effective level (95%CI) of SDAI at w14 for attaining SDAI-REM at w54 in 3, 6, and 10 mg/kg groups were 4.4 (-1.1–7.0), 8.0 (4.4–11), and 7.9 (2.0–11), and those for attaining SDAI-LDA were 18 (13–24), 22 (17–28), and 28 (22–41), respectively (Figure). These results may show that patients who did not achieve SDAI-LDA at w14 had less than 50% probability to attain SDAI-REM at w54 even in higher-dose groups. In addition, achieving at least SDAI-MDA at w14 seemed to be necessary to have high probability of attaining SDAI-LDA at w54 in 3 and 6 mg/kg groups. In contrast, high probability to attain SDAI-LDA at w54 was observed in patients with “close to SDAI-HDA” at w14 in 10 mg/kg group. The analysis using DAS28-CRP showed similar results.
Conclusions In IFX treatment for RA, the probability of attaining REM or LDA at 1 year can be predicted from the disease activity at w14 in 3 mg/kg group as well as in 6 or 10 mg/kg group. These results may provide a useful index of IFX treatment strategy (including dose-escalation) to attain REM or LDA; the goal of RA treatment.
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Takeuchi T, et al. Mod Rheumatol 2009;19:478.
Disclosure of Interest: T. Takeuchi Speakers bureau: Abbott Japan, Bristol-Myers Squibb, Chugai Pharmaceutical, Eisai, Janssen Pharmaceutical, Mitsubishi Tanabe Pharma, Novartis, Pfizer Japan, Takeda Pharmaceutical, T. Yano Employee of: Mitsubishi Tanabe Pharma, T. Inui Employee of: Mitsubishi Tanabe Pharma, T. Yoshinari Employee of: Mitsubishi Tanabe Pharma, N. Miyasaka Grant/research support from: Abbott Japan, Astellas Pharma, Chugai Pharmaceutical, Daiichi Sankyo, Mitsubishi Tanabe Pharma, Takeda Pharmaceutical, Speakers bureau: Benesis, Otsuka Pharmaceutical, T. Abe: None Declared, T. Koike Speakers bureau: Abbott Japan, Bristol-Myers Squibb, Chugai Pharmaceutical, Eisai, Mitsubishi Tanabe Pharma, Otsuka Pharmaceutical, Pfizer, Takeda Pharmaceutical