P040 The biosimilars of infliximab are equally well quantified in a clinically validated infliximab assay
A. Gils, R. Storme, E. Dreesen*, T. Van Stappen, P.J. Declerck
KU Leuven, Department of Pharmaceutical and Pharmacological Sciences, Therapeutic and Diagnostic Antibodies, Leuven, Belgium
A panel of 55 monoclonal antibodies towards the anti-tumour necrosis factor (anti-TNF) biological Remicade® (infliximab, IFX) was previously generated. The highly specific monoclonal antibody, MA-IFX6B7, was selected to quantify Remicade® in a clinically validated in house-developed infliximab ELISA, which was recently converted into CE-marked kits (distributed by ApDia and R-Biopharm). Recently, two biosimilars of Remicade®, Remsima® and Inflectra® were launched. We evaluated the 'cross-reactivity' of the MA-IFX panel towards these biosimilars and we evaluated the quantification of biosimilars in the infliximab ELISA.
First, the reactivity of the MA-IFX panel was tested using an ELISA in which either Remicade®, Remsima® or Inflectra® was coated on microtiter plates. Different concentrations (ranging from 0.8 ng/ml to 50.0 ng/ml) of each MA-IFX were applied and binding was detected using horseradish peroxidase (HRP)-conjugated rabbit-anti-mouse IgG. Secondly, calibration curves of Remicade®, Remsima® and Inflectra® (ranging from 0.6 ng/ml to 38.0 ng/ml) were applied in the in-house developed infliximab ELISA using TNF for capture and HRP-conjugated MA-IFX6B7 for detection. Statistical analyses were performed using mixed model analysis in SAS version 9.2. Thirdly, different concentrations of Remicade®, Remsima® and Inflectra® (ranging from 0.5 µg/ml to 12.0 µg/ml) were spiked in phosphate-buffered saline containing 1% bovine serum albumin. Samples were diluted and the recovery was calculated versus the Remicade® calibration curve.
Screening each of the 55 MA-IFX revealed similar reactivities towards Remicade®, Remsima® and Inflectra®. An identical reactivity of MA-IFX6B7 towards all biologicals was statistically proven (Figure 1). No significant differences were observed between the calibration curves of the three anti-TNF biologicals in the infliximab ELISA (p >.4) (Figure 2). Spiked samples revealed recoveries of 92 ± 5%, 95 ± 6% and 95 ± 5% for Remicade®, Remsima® and Inflectra®, respectively (n=3).
We have demonstrated that MA-IFX6B7 raised against Remicade® exhibits an identical reactivity towards Remsima® and Inflectra®. We analytically validated that the infliximab assay, using MA-IFX6B7, is well suited for quantification of Remsima® and Inflectra®.
“Figure 1 Dose-response curve of MA-IFX6B7 for reaction with Remicade® (solid line), Remsima® (dashed line) and Inflectra® (dotted line) (p >.5). Data are presented as mean ± SE (n = 24).”
“Figure 2: Dose-response curve of Remicade® (solid line), Remsima® (dashed line) and Inflectra® (dotted line) in the infliximab ELISA. Data are presented as mean ± SE (n = 6). The fitted curves show no significant differences (p >.4).”