Module 9 2021

22/03/2021

Challenges in immunogenicity assessment

• Cut-point calculations (analytical & biologicals outliers, pre- vs in-study cut points) • Sensitivity of assays • Assay controls (PC, NC, acceptance criteria) • Pre-existing antibodies (e.g., anti-PEG, rheumatoid factors, HAMA,…) • Matrix effects (complement components,…) • Drug tolerance (often THE bioanalytical challenge for therapeutic mAb)

• Target interference (monomeric soluble target can bind therapeutic and prevent ADA binding  false negative; membrane-bound target or multimeric soluble target may form bridge with therapeutic  false positive)

sulfo-Tag

TmAb TmAb

biotin

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Assay Controls

Positive control (important for assay development and validation e.g., determination of assay sensitivity, assessment of assay drug tolerance) • affinity purified polyclonal sera from hyperimmunised animals

• monoclonal antibodies, spiked into appropriate matrix Negative control (important for cut-off determination)

• normal human sera (pooled) • pre-therapy sera from patients • irrelevant antibody Immune response in patients • individual polyclonal response • varying over time in a patient; varying between patients (transient versus persistent Abs, affinity maturation, titer, affinity)  ideal positive control Ab: sera from patients who develop an immune response (not available)

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