The efficacy and safety of SB4, a biosimilar of reference etanercept (ETN), are comparable to those of ETN for up to 52 weeks in patients with active rheumatoid arthritis (RA), based on the findings from a study published in Rheumatology.

A phase 3, randomized, double-blind, multicenter study of 596 patients with moderate to severe RA who had been taking methotrexate for ≥6 months sought to compare treatment with subcutaneous SB4 (n=299) vs subcutaneous ETN (n=297). Investigators randomly assigned eligible patients in a 1:1 ratio to treatment with either SB4 50 mg/wk or ETN 50 mg/wk for up to 52 weeks. A total of 505 patients completed the 52-week study.

The primary end point of the trial was the proportion of patients who achieved ≥20% improvement in American College of Rheumatology response criteria (ACR20) at
week 24. Efficacy end points up to week 52 included ACR response rates, 28-joint Disease Activity Score, Simplified and Clinical Disease Activity Indices, and changes in modified total Sharp score (mTSS). The investigators also compared the safety and immunogenicity of the two agents.


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The investigators found that ACR20 response rates at week 52 were comparable between the SB4 and ETN arms (80.8% vs 81.5%, respectively). All efficacy results, which were also comparable between the two groups, were maintained up to week 52. Radiographic progression was also comparable between the groups, with mTSS changes from baseline of 0.45 with SB4 and 0.74 with ETN.

The safety profiles of SB4 and ETN were similar. The incidence of antidrug antibody development up to week 52 was 1.0% with SB4 treatment vs 13.2% with ETN treatment.

The researchers concluded that SB4 demonstrated comparable clinical efficacy, including radiographic progression, to ETN for up to 52 weeks. SB4 was well tolerated, with a 1-year safety profile that was similar to that of ETN.

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Reference

Emery P, Vencovský J, Sylwestrzak A, et al.  52-week results of the phase 3 randomized study comparing SB4 with reference etanercept in patients with active rheumatoid arthritis [published online August 19, 2017]. Rheumatology. doi: 10.1093/rheumatology/kex269/4085771