Long-Term Data Support Switching From Reference Infliximab to SB2

New data from an extension period of a phase 3 study of Samsung Bioepis’ SB2 (Renflexis) in patients with moderate to severe rheumatoid arthritis (RA) found that there was no clinically meaningful difference in safety, efficacy, or immunogenicity in patients who were switched from reference infliximab to the biosimilar compared with patients who continued treatment with either the reference or the biosimilar without switching. Additionally, patients who received the biosimilar alone, and were not switched, maintained long-term efficacy, safety, and immunogenicity that was comparable with patients who received the reference product alone.

The new data present clinical efficacy and safety results of SB2 in patients with RA for up to 78 weeks (previous reports were up to week 54). The objective of this extension was to investigate whether patients being treated for RA with reference infliximab could be switched to SB2 without major concerns, and whether comparable efficacy, safety, and immunogenicity were maintained after the switch (compared with continued treatment with either reference infliximab or SB2 only).

Patients with RA who had participated in the original 54-week, double-blind period and who were willing to participate in the extension (n = 396) were randomized to either transition to SB2 from reference infliximab (n = 94) or to continue treatment with reference infliximab (n = 101) or SB2 (n = 201), up to week 70. The final follow-up occurred at week 78.

Treatment efficacy among the 3 arms was comparable at week 78 in terms of the American College of Rheumatology (ACR) responses of 20%, 50%, and 70% improvement:

• The percentage of patients achieving a response of ACR20 at week 78 was 63.5% in the reference infliximab—SB2 group, 68% in the reference-only group, and 68.3% in the SB2-only group
• The percentage of patients achieving ACR50 at week 78 was 37.6% in the reference infliximab—SB2 group, 47.3% in the reference-only group, and 40.6% in the SB2-only group
• The percentage of patients achieving ACR70 at week 78 was 22.4% in the reference infliximab—SB2 group, 31.2% in the reference-only group, and 25.6% in the SB2-only group

The percentage of patients achieving good European League Against Rheumatism (EULAR) responses at week 78 were as follows:

• 32.9% the reference infliximab—SB2 group
• 34.4% in the reference-only group
• 35.6% in the SB2-only group

The percentage of patients in each arm who developed new ADAs to their assigned treatment were as follows:

• 14.6% in the reference infliximab—SB2 group
• 14.9% in the reference-only group
• 14.1% in the SB2-only group

The study’s authors concluded that the clinical profile of SB2, administered either in the long term or when switched from the reference infliximab, is comparable with that of the reference. “Our data showing that switching from originator to biosimilar is safe and effective are corroborated by the recent observations in the NOR-SWITCH and DANBIO [studies],” said the authors.