How is immunogenicity of therapeutic proteins assessed?

Immunogenicity (immune response to therapeutic proteins) assessment involves: 1) Tiered testing approach - screening assay (sensitive, detects all ADA), confirmatory assay (specific, confirms positive screens), characterization (neutralizing activity, isotype, epitope mapping). 2) Assay formats - bridging ELISA or electrochemiluminescence (MSD) for screening; cell-based assays for neutralizing antibodies. 3) Drug tolerance - free drug interferes with ADA detection; acid dissociation, solid-phase extraction, or target interference mitigation needed. 4) Clinical correlation - relate ADA to PK changes, loss of efficacy, hypersensitivity, and cross-reactivity to endogenous proteins. 5) Risk assessment - patient factors (immune status, genetic predisposition), product factors (sequence, aggregates, glycosylation), and treatment factors (route, dose, duration). Pre-clinical assessment uses transgenic mice or non-human primates. Cut-point determination crucial for assay validation.