Considerations on development, validation, application, and quality control of immuno(metric) biomarker assays in clinical cancer research: an EORTC-NCI working group report.

A major dilemma associated with immuno(metric) assays for biomarkers is that various kits employing antibodies with differing specificities and binding affinities may generate non-equivalent test results. Also, variation in sample processing and the use of different standards (reference material) may result in discordant test results. Therefore, assays and procedures should be standardized and the quality of biomarker assay results should be monitored by continuous between-laboratory proficiency testing of performance. External quality control requires an established network of expert laboratories in which the investigators interact freely and where technical issues are discussed. Although such networking is more often praised than practiced, we strongly endorse and advocate between-laboratory exchange of experience and information. The present study discusses analytical aspects of immuno(metric) biomarker assays and presents recommendations of the Receptor and Biomarker Group of the EORTC (European Organisation for Research and Treatment of Cancer) how such tests should be validated for first time and day to day use. Moreover, a model for an appropriate quality assurance program is presented.