What is the difference between Renflexis (infliximab) and Inflectra (infliximab)?

Renflexis vs Inflectra: Key Differences

Renflexis and Inflectra are NOT different drugs—they are simply different brand names for distinct biosimilar infliximab products, with Renflexis being SB2 and Inflectra being CT-P13. Both are approved biosimilars to the reference product Remicade, but they are manufactured through different processes and are structurally distinct molecules 1, 2.

Product Identity

• Inflectra is the brand name for biosimilar CT-P13 (also marketed as Remsima in some regions) 3, 4
• Renflexis is the brand name for biosimilar SB2 (also marketed as Flixabi in the EU) 2, 5
• Both are structurally different from each other but exhibit comparable physicochemical characteristics, pharmaceutical effectiveness, and immunogenicity compared to reference infliximab 1

Clinical Equivalence

Both biosimilars demonstrate equivalent efficacy and safety to the originator infliximab and to each other in clinical practice. 6, 3

Immunogenicity Data

• In the PANTS observational cohort of 751 Crohn's disease patients, immunogenicity rates at week 54 were 26% for Remicade and 28% for biosimilar infliximab (Inflectra/Remsima), showing no clinically meaningful difference 6, 3
• Both biosimilars share common immunodominant epitopes with reference infliximab, meaning antibody formation patterns are similar across all three products 1

Switching Between Products

• Switching from originator infliximab to either Renflexis or Inflectra is safe and effective in patients who are in stable remission 6, 7
• Multiple switches between biosimilars (e.g., originator → Inflectra → Renflexis) show equivalent efficacy and safety compared to single switches 7, 2
• In a nationwide cohort of 271 IBD patients, double switching (IFX to CT-P13 to SB2) showed no statistically significant difference in efficacy or safety compared to single switching (adjusted OR 1.33,95% CI 0.74-2.41, P=0.34) 7
• Among 90 patients converted to biosimilars in a health system initiative, 87.8% were maintained on a single biosimilar without requiring switches 5

Therapeutic Drug Monitoring

All current infliximab assays can accurately measure both Renflexis and Inflectra drug levels without clinically significant differences. 1

• Four different ELISA assays demonstrated good correlation between SB2, CT-P13, and reference infliximab in spiked serum samples 1
• The observed bias between the original drug and biosimilars is clinically insignificant and less than the usual analytical variability of these methods 1
• Anti-drug antibody testing works equivalently for both biosimilars 1

Regulatory Approval

• Both biosimilars are approved by the European Medicines Agency and FDA for all indications where reference infliximab is approved, including inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and psoriasis 4, 2
• Approval was based on comprehensive comparability data demonstrating pharmacokinetic and pharmacodynamic equivalence to the reference product 3
• The British Society of Gastroenterology recommends that biosimilar infliximab may be used for IBD patients starting treatment and that patients on originator infliximab can be switched to biosimilar infliximab if in stable response or remission 6

Clinical Practice Implications

The choice between Renflexis and Inflectra should be made based on local commissioning context, cost considerations, and formulary availability rather than clinical differences. 6

• Both biosimilars should be prescribed by brand name to ensure full traceability and accountability 6
• Patients should be fully informed about biosimilar use 6
• Real-world evidence supports the efficacy of both biosimilars in inflammatory bowel disease, including in extrapolated indications 2

Common Pitfalls to Avoid

• Do not assume these are interchangeable products—while both are biosimilars to infliximab, they are distinct molecules that require separate prescribing 6, 1
• Do not hesitate to switch between biosimilars if needed—evidence supports that multiple switches do not compromise efficacy or safety 7, 2
• Do not use different therapeutic drug monitoring assays after switching—current assays work equivalently for both products 1