Introduction to qualification and validation of an immunoassay

Immunoassays play an important role in drug development of products targeting the immune system. Consistent quality of the results from an immunoassay is essential to make unbiased and accurate claims about the drug product during preclinical and clinical development stages. Assay qualification and validation shed light on the performance of the assay. It is the first evaluation and the verification, respectively, of the assay's performance. This tutorial explains and illustrates the calculation methodology for important assay qualification parameters including precision, relative accuracy, linearity, the lower limit of quantification (LLOQ), the upper limit of quantification (ULOQ), the assay range and dilutability. This tutorial focuses on assays used for (pre-) clinical purposes, characterized by a lognormal distribution of the measurements on its original untransformed scale and by the lack of well characterized reference material. Statistical calculations are illustrated with qualification data from an enzyme-linked immunosorbent assay (ELISA) vaccine immunoassay.