Covance validate Affimer reagents as critical PK assay reagents

Reagents that can specifically identify and accurately quantify individual biotherapeutics within a patient sample are essential to the regulatory bioanalysis of therapeutic proteins. Used throughout the drug development and clinical trials processes these reagents allow the movement of biotherapeutics, such as antibodies, to be tracked within patients’ bodies. In a recent webinar (link is external) scientists from Covance laboratories discuss their successful validation of Affimer reagents as critical reagents in a key regulatory ligand binding assay.

Antibodies have long represented the benchmark for affinity reagents used in ligand binding assays to monitor therapeutic proteins. While traditional antibodies have been sufficiently refined to offer specificity, sensitivity and a reasonable level of reliability, these reagents remain limited by their development times, complexity to culture on an industrial scale and the unavoidable lot-to-lot variation that arises in their assay performance. 

With an increasing number of antibody-based therapeutics entering the market there is an obvious increased need for validated reagents to monitor these biotherapeutics, both during the drug development process and beyond. Affimer reagents show high target specificity and sensitivity, can be rapidly developed and easily produced without batch-to-batch variation, and so meet the key requirements for critical reagents in pharmacokinetic (PK) assays.

anti-trastuzumab affimer
Use of the anti-trastuzumab Affimer binder within the regulatory assay allowed a dynamic range twice that of the current antibody-based method.

This study was performed by Covance Laboratories to assess the use of an Affimer reagent specific to the therapeutic antibody trastuzumab as a capture reagent in a standard ELISA regulatory ligand binding assay. The goal of the project was to replace the use of recombinant HER2 as a capture reagent in the current assay with an Affimer protein. As part of this Covance scientists qualified the performance of the Affimer reagent using the regulatory criteria required for critical PK assay reagents.

Access the webinar (link is external) to learn more about the performance improvements Affimer reagents can offer as PK assay reagents, including: the ability of Affimer reagents to accurately detect and quantify Trastuzumab within both standard and disease state matrix, with no observable matrix effects; an increased dynamic range of over twice that of the current antibody-based method; no batch-to-batch variability; and good target sensitivity. Furthermore, the phage-library selection, lack of requirement for affinity maturation and simple scaffold structure of Affimer reagents means that these highly specific binders are routinely identified and developed within just 12-14 weeks and can be simply and cost effectively cultured in bacterial systems. This avoid the delays that can often hinder and affect the economics of drug development programmes, and bring about reduced project timelines and costs.

These data produced and presented by Covance demonstrate the validity of Affimer binders as alternatives or complimentary critical reagents to traditional antibodies within regulated PK assays for therapeutic antibodies, and highlight the scope of Affimer reagents in a regulated bioanalysis setting.