Design of experiment in assessing robustness and for qualification of a cell based potency assay

What is it about?

A key milestone in bioassay development is the execution of robustness studies. It is important that the bioassay is sufficiently robust to determine manufacturing consistency and to achieve this a bioassay may require further development throughout a drugs lifecycle. The cell based assay, in a thaw-for-use format, was developed to measure the specific cytotoxic activity of an antibody drug conjugate towards a cell line expressing the target antigen. The objective of the study was to assess the robustness of the methodology and to qualify the methodology for determining the relative potency of the antibody drug conjugate. Design of Experiment (DoE) approach for robustness and for validation is increasingly being advocated for bioassays and can provided an assessment of the impact from the interaction of related experimental conditions. There were 8 factors considered to be important in assessing the robustness of the methodology. With 8 factors the factorial design becomes very large and difficult to manage and a different approach was taken to incorporate all 8 factors into the study and this is discussed in the paper. The study utilised five mock potency samples to assess robustness and to establish the precision, accuracy/ bias, linearity and range of the methodology using the centre point data of the DoE.

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Why is it important?

This approach, in which the assessment of robustness is coupled to qualification, provided a larger control data set giving greater assurance to where trends occurred and when these were significantly different. The normalising of the mock potency data to 100% provided additional power to the analysis allowing for optimal assay condition to be established that would minimise inaccuracy in the methodology.

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