1. Antibodies to Infliximab in Remicade-Treated Rheumatic Patients Show Identical Reactivity Towards Biosimilars
ACR/ARHP Annual Meeting, San Francisco, November
Begoña Ruiz-Argüello, Ainara Maguregui, Ainhoa Ruiz del Agua, Dora Pascual-Salcedo, Ana Martínez , Teresa Jurado, Chamaida Plasencia, Alejandro Balsa, Francisca Llinares-Tello, José Rosas, Nerea Torres, Antonio Martínez and Daniel Nagore
R&D, Progenika-Grifols, Derio, Spain, Immunology Unit, La Paz University Hospital-Immunology, Madrid, Spain, Immunology, La Paz University Hospital-Idipaz, Madrid, Spain, Rheumatology Unit, La Paz University Hospital-Rheumatology, Madrid, Spain, Rheumatology, La Paz University Hospital-Rheumatology Department, Madrid, Spain, Clinical Analysis, Hospital Marina Baixa, Clinical Analysis, Villajoyosa, Spain, Rheumatology, Hospital Marina Baixa, Villajoyosa, Spain

2. Disclosure
I am disclosing financial or other relationship as follows:
Full time employee of Progenika-Grifols.

3. Background and Introduction
The infliximab (IFX) biosimilar CT-P13 was approved in 2013 by the EMA for use across all the same indications as Remicade™ (RMC) (infliximab)1,2
CT-P13 is marketed as two brand names: Inflectra™ (IFT) and Remsima™ (RMS)
All biological drugs are potentially immunogenic
Immunogenicity is strongly related to:
Loss of clinical response
Adverse effects
Discontinuation of treatment
Rates of Anti-Drug Antibodies to CT-P13 are the same as RMC in RA and AS1,2
Previous work in Inflammatory Bowel Disease patients has shown that anti-IFX Antibodies (ATI) of RMC-treated patients cross-react with CT-P13 (RMS)3
Immunogenicity equivalence between the biosimilar and the reference molecule is a cause for concern
1Yoo DH. Ann Rheum Dis 2013;72: The PLANETRA study
2Park W. Ann Rheum Dis 2013; 72: The PLANETAS study
3Ben-Horin S et al. Gut Published Online First: 2015 Apr20 doi: /gutjnl

4. Background data
Ben-Horin S et al. Gut Published Online First: 2015 Apr20 doi: /gutjnl

5. Objective
Investigate whether antibodies developed by RMC-treated patients cross-react with CT-P13 (RMS/IFT) in rheumatic patients

6. Design Retrospective, observational
250 adult rheumatic patients (RA and AS) with RMC treatment (biosimilar-naïve) selected retrospectively
37 IFX-naïve control rheumatic patients
21 control healthy individuals (blood donors)
Trough sera collected for drug levels and ATI testing
Cut-point of the assays has been determined using IFX-naïve rheumatic and control population

7. Study population Clinical characteristics RMC-treated patients (N=250)
Median age (IQR 25-75, range)
52.5 (42-63, 21-82)
Sex
Male
39.8%
Female
60.2%
Disease RA
43.5% AS
56.5%
Mean IFX therapy, years (IQR 25-75, range)
4.9 ( , )
Concomitant immunomodulators
Yes
76.9% No
23.1%
Controls (N=58)
IFX-naïve rheumatic patients
37 (63.8%)
Healthy individuals
21 (36.2%)

8. Promonitor ANTI-IFX CE-marked kit
Methods to measure ATI
Bridging ELISA
Method A
Method B
Method C
ATI
HRP-RMC
conjugate
RMC-precoated plate
IFT-precoated plate
HRP-IFT
RMS-precoated plate
HRP-RMS
Promonitor ANTI-IFX CE-marked kit
CT-P13 (RMS) assay
CT-P13 (IFT) assay

9. Assays calibration curves
No differences between methods (p=0.949)
Inter-assay CV (1-7%)

10. Cut-point determination
No differences between methods (p>0.05)
No differences between control patients (p>0.05)
The cut-point was determined to be 5 AU/mL for all assays

11. ATI determination towards Remicade
All patients tested ATI-positive in Method A (126) were found positive when either RMS (Method B) or IFT (Method C) were used to detect the antibodies
There were not differences between the three groups (p>0.05)
ATI-positive (50.4%)
ATI-negative (≤5 AU/mL) (49.6%) A B C A B C

12. Statistically significant?
Cross-reactivity between ATI and CT-P13
100% of patients positive to anti-RMC antibodies cross-reacted against CT-P13 (either IFT or RMS)
ATI concentrations showed the same magnitude in RMC or CT-P13-based assays
Same RMC epitopes present in CT-P13
Method A
Method B
Method C
Statistically significant?
ATI-positive
Median ATI (AU/mL)
57.8
61.5
62.1 No
ATI-negative
Median OD, ATI conc
0.074
(≤5 AU/mL)
0.092
0.096
Control
0.081
0.080
0.085

13. Assay correlation
Spearman coefficient of correlation (upper panels) and Blant-Altman plots (lower panels) (bias, 95% CI) (AU/mL) are shown
33.9 ( ) AU/mL
26.8 ( ) AU/mL
-7.2 ( ) AU/mL

14. Study limitations and discussion
CT-P13 might present new epitopes which can be relevant after switching. Potential new epitopes could raise an immune response that is not addressed in this study.
The study addresses the importance of determining cross-reactivity, but it does not evaluate different immune titers (high and low affinity antibodies).
Bridging ELISA does not efficiently detect IgG4 isotype which might be relevant for some patients with prolonged immune response to IFX, although this should not lead to false negatives.
The inflammatory burden of RA and AS is different, however we did not observe any significant differences in either the cross-reactivity or magnitude of ATI concentration in separate analysis:
Median ATI of 56, 67, 67.6 AU/mL (A,B,C, p>0.05) and 56.5, 61.2, 58.3 AU/mL (A, B, C, p>0.05) for RA and AS, respectively .

15. Conclusions
ATI of RMC-treated rheumatic patients show cross-reaction with the biosimilar CT-P13 (either RMS or IFT).
Results suggest that the immune response is elicited by the same epitopes regardless of the molecule source.
Results imply that if a patient with anti-RMC antibodies is switched to CT- P13, previous ATI will interact with the biosimilar and potentially lead to loss of response.
Results are in agreement with previous data in patients with inflammatory bowel diseases in which ATI were also shown to be cross-reactive with CT- P13 (RMS).

16. Thank you! Dora Pascual-Salcedo, PhD Ana Martínez-Feitó, PhD
Teresa Jurado
Chamaida Plasencia, MD, PhD
Alejandro Balsa, MD, PhD
José Rosas, MD, PhD
Francisca Llinares-Tello
M. Begoña Ruiz-Argüello, PhD
Ainara Maguregui
Ainhoa Ruiz del Agua, PhD
Nerea Torres, PhD
Antonio Martínez, PhD