Statistical Tutorial for Cut‐Point Determination in Immunogenicity Studies

Administration of therapeutic protein products might potentially elicit an immune response via production of Anti-Drug Antibodies (ADA). This immune response can cause some clinical consequences ranging from mild to harmful for the patient, affecting the safety and efficacy of the drug. Therefore, assessment of Immunogenicity and the ability to follow possible associations between ADA assay measurements and clinical events is one of the key parts of clinical safety evaluation in both clinical and preclinical areas. In order to assess the immunogenicity of biological drug molecules, it is important to develop and validate reliable laboratory methods and evaluate various performance characteristics during development and validation phases. Determination of the screening assay cut-point and establishment of the confirmatory assay cut-point are fundamental aspects of ADA assay validation. Existing regulatory guidance documents addressing immunogenicity topics (immunoassays) cover the development and validation of reliable laboratory methods, but there is a need for more comprehensive discussions on statistical evaluation methods. While there is literature available on statistical methods for cut-point estimation, this tutorial aims to provide additional statistical considerations specifically tailored for ADA assay development and validation cut-points. Furthermore, practical R code snippets are provided to facilitate the implementation of the key evaluation steps. This resource aims to enhance the rigor and reliability of ADA assay validation cut-point evaluation, ultimately contributing to more robust immunogenicity assessments in clinical studies.