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Qualification and Development of VEGF Binding Assay using the Intellicyt® iQue Screener PLUS
Presenter: Katie Chapple of Sartorius Stedim BioOutsource Ltd.
Date and Time: Tuesday, May 1, 2018 3:15 PM to 4:45 PM
Authors: Katie J Chapple, Benjamin J Tyrrell
Sartorius Stedim BioOutsource have developed a suite of binding assays using the Intellicyt® iQue Screener PLUS. The Intellicyt® iQue Screener PLUS achieves a faster assay throughput than traditional flow cytometers by sampling only microliters from each well and delivering an air-gap-delimited flow of samples to the detectors, therefore transforming a low throughput, time-consuming flow cytometry approach into a high throughput process.
Bevacizumab is a humanised monoclonal antibody which mediates its activity through high affinity binding to VEGF (vascular endothelial growth factor). VEGF, a signalling protein, is involved in the initiation of vasculogenesis and angiogenesis of blood vessels. Due to the reliance of solid tumours on efficient angiogenesis to grow beyond a few mm³ in volume, bevacizumab is used as a combination therapy for a number of malignancies including metastatic colorectal cancer and metastatic kidney cancer.
This in vitro cell-based binding assay utilised a flow cytometry format to measure antibody binding. The VEGF expressing target cells were incubated with a dilution series of bevacizumab. The antibody-bound cells were then detected using a fluorescently-labelled secondary anti-IgG antibody. The degree of antibody binding can be quantified using a fluorescence readout on the iQue® Screener PLUS in approximately 13 minutes per plate.
The data presented here was obtained from an assay qualification performed at Sartorius Stedim BioOutsource. During the qualification study, the data collected demonstrated that the assay is accurate, reproducible and precise over a linear range of 50 to 200% relative to the reference standard and was specific to bevacizumab. The methodology was deemed fit for the purposes of evaluating the functional comparability and potency of bevacizumab biosimilar and innovator material. The benefits of this commercially available assay are that it is easy-to-use, highly reproducible, and saves a large proportion of assay development time, translating into overall cost savings in a biosimilar development program.