Quality Assessment of Therapeutic Drug Monitoring Assays of Therapeutic Antibodies Across Europe: An Update

Immune mediated inflammatory diseases (IMIDs) are common, chronic, inflammatory diseases. There has been an expansion of monoclonal antibodies to treat the disease. However, the response is not universal; reasons for non-response may include suboptimal drug concentrations for which therapeutic drug monitoring (TDM) may lead to improved outcomes. Several laboratory assays are available to measure biologic drug concentrations, but variation in assay accuracy may introduce bias. External quality assessments (EQA) provide assurance of the performance of a laboratory test. The aim of this work was to survey current quality assessment procedures that are in place in laboratories undertaking TDM of therapeutic antibodies for the treatment of IMIDs to guide clinical decision making across Europe. A survey was sent out to institutions undertaking TDM across Europe. In total, 26 institutions responded; the vast majority (96.2%) of institutions utilize an internal quality control, with 42% of institutions not reporting participation in a national EQA scheme. Barriers to EQA participation included insufficient information about relevant organizations and financial constraints. These results demonstrate that, although TDM assay performance is well controlled locally, better access to EQA and standards may further aid the translatability of results between laboratories and aid the adoption of published reference values.