Interchangeability, Immunogenecity and Infliximab Biosimilars

A recent study (G Fiorino et al. IBD 2018; 24: 601-6, editorial by KH Katsanos et al 465-6) provides more data on “full interchangeability” in regards to infliximab (IFX) and biosimilars CT-P13 and SB2. Full abstract below.

Key finding in study:

  • Antibodies to infliximab (ATI) cross-reacted with any type of IFX or IFX-biosimilar

Points from the editorial:

  • “The landmark NOR-SWITCH randomized controlled trial showed that 1-time switching from RMC [Remicade] to CT-P13 is not inferior to continued treatment with the infliximab originator…there are no data regarding multiple switches…Consequently, cross-switching (switching between 2 biosimilars), reverse switching (switching from biosimilar to its originator) or multiple/repeated switching is not currently recommended.”
  • This study, however, shows that “if you have already developed antibodies to 1 infliximab product, there is no point in switching to another infliximab product.”

Abstract:

BackgroundInfliximab (IFX) biosimilars CT-P13 and SB2 have comparable efficacy, safety, and immunogenicity to the originator Remicade (RMC). However, concerns about cross-switching patients between the 3 brands were raised in the absence of cross reactivity data between them. We aimed to determine whether antibodies to infliximab (ATI) in inflammatory bowel disease (IBD) patients cross-react with RMC, CT-P13, and SB2.

MethodsBased on previous ATI status, samples from 34 patients participating in the BIOSIM01 study (13 RMC, 9 CT-P13, and 12 switchers) were selected. Patients were treated with either RMC only, or CT-P13 only, or with RMC switched to CT-P13. Additionally, 28 IFX-naïve patients were assayed as controls. In total, 180 samples were analyzed. ATI trough levels were measured in parallel with 3 different bridging Enzyme Linked Immunosorbent Assays constructed using the 3 drugs. Spearman’s coefficient and percentages of agreement were used to study the correlation between each assay.

ResultsIn total, 76 samples out of 152 IFX-treated patient samples were ATI-positive (30 RMC, 14 CT-P13, and 32 switchers). All resulted ATI-positive when either CT-P13 or SB2 bridging assays were used. The overall percentage of agreement was 100% when compared either with CT-P13 or SB2 assays. No significant differences were found among ATI levels and coefficients (Spearman’s 0.98 to 1.0, P < 0.0001).

ConclusionsATI of RMC-treated, CT-P13-treated or RMC to CT-P13 switched patients show full cross-reactivity with CT-P13 and SB2. Findings suggest that immunodominant epitopes in the reference and CT-P13 drugs are equally present in SB2. Data support full interchangeability between biosimilars in regard to immunogenicity.

My take: In patients doing well with IFX, switching to a biosimilar is not currently recommended.  In patients naive to IFX, use of IFX or biosimilar is expected to have similar efficacy.

Related study: B Kang et al. IBD 2018; 24: 607-16.  This prospective study of 36 pediatric patients did not identify any significant differences in efficacy…or immunogenicity after switching from IFX to CT-P13.

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