Effectiveness and safety of sarilumab in patients with rheumatoid arthritis: A multicenter, retrospective, inverse probability of treatment-weighted analysis based on the FRAB-registry.

Objective: The efficacy and safety of sarilumab (SARI) were investigated in real-world clinical practice in Japan.

Method: Subjects were 121 rheumatoid arthritis (RA) patients in 23 medical institutions in Fukuoka Prefecture, Japan, who started treatment with SARI between May 2018 and November 2021. Data on the SARI starting dose, patients' baseline characteristics, disease activity, and blood test data at the start of treatment, as well as follow-up data on the SARI dose, disease activity, and adverse events until Week 52. Safety and the continuation rate calculated by the Kaplan-Meier method were evaluated, and the effectiveness of treatment at 1 year was assessed using the clinical disease activity index (CDAI). Patients' baseline characteristics for which significant differences were evident were adjusted with a propensity score by using the inverse probability of treatment-weighting (IPTW) method.

Results: The continuation rate at Week 52 was 66.1%. The CDAI showed significant improvement from Week 4 that was maintained until Week 52. Comparisons conducted after IPTW adjustment for patients' baseline characteristics for which significant differences were evident revealed no significant differences at Week 52 between the groups classified by higher or lower body mass index (BMI) (p = 0.231), serious comorbidities (p = 0.973), MTX use (p = 0.321), or prior treatment with ≤ 1 or ≥ 2 biologic and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) (p = 0.765).

Conclusions: The results showed that the efficacy of SARI is not affected by BMI, comorbidities, MTX use, or the number of prior b/tsDMARDs, and no new safety concerns were apparent. Key Points • This is the first real-world clinical study to report on the efficacy and safety of SARI in Japan. The results of this study indicate that the efficacy of SARI was not affected by BMI, comorbidities, MTX use, or number of previous b/tsDMARDs. • It was shown that SARI can be used in a Japanese population without any new side effects.