Background Recently, the European Medicines Agency approved a biosimilar to infliximab, CT-P13. Biosimilars are not only required to have biochemical and pharmacokinetics (PK) equivalence, but also must demonstrate similarity in their therapeutic effectiveness, safety and immunogenicity. The PLANETAS was a randomized double-blind, parallel group study for demonstrating PK equivalence between biosimilar infliximab (CT-P13) and innovator infliximab (INX) in patients with ankylosing spondylitis (AS).
Objectives To compare disease activity, disability and mobility indices of CT-P13 and INX and to assess the effect of anti-drug antibody (ADA) on the observed indices in patients participated in the PLANETAS.
Methods In the PLANETAS, key secondary endpoints captured the clinical measures of disease activity via ASAS20/40 and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), disability via the Bath Ankylosing Spondylitis Functional Index (BASFI) and mobility via the Bath Ankylosing Spondylitis Metrology Index (BASMI). The Student's t test was used to compare mean change of three indices from baseline in both treatment groups. ADA was measured using the electrochemiluminescent methodology. Clinical responses, regardless of treatment groups, were examined in relation to the presence of the ADA.
Results 250 patients with AS were treated with either CT-P13 or INX. Baseline comparability was demonstrated with each of these 3 indices. At week 54, BASDAI improved significantly from baseline in both treatment groups (CT-P13: from 6.74 to 3.78 and INX: from 6.57 to 3.70) and this improvement was similar between groups (difference of means -0.29; CI of the difference -0.91 to 0.32). BASFI and BASMI also improved in similar pattern: BASFI (CT-P13: from 6.20 to 3.42 and INX: from 6.24 to 3.46) and BASMI (CT-P13: from 4.0 to 2.8 and INX: from 4.1 to 3.2). At week 54, 50% improvement of the baseline BASDAI (BASDAI50) was achieved in 44.3% for CT-P13 and 46.3% for INX and BASDAI50 response rate was comparable between the two groups (p=0.7737). Overall, no statistical significance in clinical responses between the treatment groups at week 54 was found for all indices. Higher ASAS20/40 responses were seen in the ADA negative patients (72.7%/56.5%) compared with ADA positive patients (54.7%/37.7%) at week 54. Mean change from baseline for BASDAI and BASFI improved significantly in ADA negative subgroup than ADA positive subgroup (BASDAI: -3.13 vs. -2.30 and BASFI: -2.97 vs. -2.18) but no clear association with ADA was seen for BASMI.
Conclusions Well-established indices of disease activity, disability and mobility in patients with AS were improved and statistically similar between CT-P13 and INX group. ASAS20/40, BASDAI and BASFI by ADA subgroup showed evidence of a relationship which was higher clinical responses in ADA negative subgroup.
Disclosure of Interest W. Park Grant/research support: Celltrion, Consultant for: Celltrion, Speakers bureau: Celltrion, D. H. Yoo Grant/research support: Celltrion, Consultant for: Celltrion, Speakers bureau: Celltrion, S. Szántό: None declared, F. Berghea: None declared, M. Brzosko Grant/research support: Celltrion, P. Wiland Grant/research support: Celltrion, S. Smiyan Grant/research support: Celltrion, R. Araiza-Casillas Grant/research support: Celltrion, F. Díaz-González Grant/research support: Celltrion, J. H. Suh Employee of: Celltrion