Study Compares Long-Term Efficacy, Safety of Infliximab Biosimilar to Reference Drug in RA

SAN FRANCISCO, CA—At the 2015 ACR/ARHP Annual Meeting, study investigators reported that SB2, an infliximab biosimilar, demonstrated comparable long-term efficacy, safety, and immunogenicity to that of the infliximab reference product up to 54 weeks in patients with moderate to severe rheumatoid arthritis (RA).

Josef S. Smolen, MD, from Medical University of Vienna, Vienna, Austria, and colleagues conducted a Phase 3, randomized, double-blind study to compare the efficacy, safety, and immunogenicity between SB2 and infliximab, including radiographic damage at Week 54.

For the study, patients with moderate to severe RA (n=584) despite methotrexate therapy were randomized to either SB2 or infliximab 3mg/kg with dose increments up to 7.5mg/kg after Week 30. Study investigators assessed safety, efficacy, and immunogenicity outcomes up to Week 54 at each visit and radiographic damage was assessed by change of modified total sharp score (mTSS) from baseline to Week 54.

A total of 452 patients completed 54 weeks of treatment. In the SB2 group, ACR20 response was seen in 50.7% and in the infliximab group, 52.6%. ACR50 responses were 32.1% vs. 29.7%, respectively, and ACR70 responses were 18.3% vs. 17.7%, respectively. 

Secondary efficacy measures at Week 54 such as DAS28 or EULAR response were similar between the two arms with a mean change of 0.38 in the SB2 group vs. 0.37 in the infliximab group. Overall anti-drug antibody positivity was 62.4% in the SB2 group and 57.5% in the infliximab group (P=0.270).

Safety profiles for SB2 and infliximab were also similar with total infections seen in 29.3% of the SB2 group vs. 37.5% of the infliximab group. Serious infections occurred in 3.1% of the SB2 group vs. 2.0% of the infliximab group.

Dr. Smolen pointed out that radiographic progression was comparable between SB2 and infliximab at 54 weeks. Overall, both study arms demonstrated similar long-term efficacy, safety, and immunogenicity.