Theoretical Considerations and Practical Approaches to Address the Effect of Anti-drug Antibody (ADA) on Quantification of Biotherapeutics in Circulation

Abstract

Abstract. Continuous improvement in bioanalytical method development is desired in order to ensure the quality of the data and to better support pharmacokinetic (PK) and safety studies of biotherapeutics. One area that has been getting increasing attention recently is in the assessment of "free" and "total" analyte and the impact of the assay format on those assessments. To compliment these considerations, the authors provide a critical review of available literature and prospectively explore methods to mitigate the potential impact of anti-drug antibody on PK assay measurement. This challenge is of particular interest and importance since biotherapeutic drugs often elicit an immune response, and thus may have a direct impact on quantification of the drug for its PK and safety evaluations.

Assessment and Reporting of the Clinical Immunogenicity of Therapeutic Proteins and Peptides—Harmonized Terminology and Tactical Recommendations

“…Alternatively, some assay formats can detect "total" drug, which comprises free drug, target-bound drug, and possibly ADA-bound drug. Like ADA methods, PK immunoassays cannot be taken for granted; the format of PK immunoassays can vary widely in their susceptibility to interference by ADA (47). For example, the accuracy of PK immunoassays based on a format of capture and detection of a mAb drug using the drug target or anti-idiotypic antibodies is not expected to be affected by the presence of non-neutralizing ADA (nonNAb), whereas NAb can produce significantly undervalued drug concentration results.…”

Recommendations for the Assessment and Management of Pre-existing Drug-Reactive Antibodies During Biotherapeutic Development

“…ADA, as well as pre-existing antibodies, may not only interfere but also directly enhance drug clearance by forming immune complexes. In order to better understand the specific nature of the ADA impact, including pre-existing antibodies, on drug PK, an additional investigation may be required, as previously described (54,55).…”

“…These true antibody-positive samples can be identified by a characterization assay, such as immunodepletion. Alternatively, a practical conservative approach using a pre-established subjective % inhibition cut point in a standard specificity inhibition assay can also eliminate pre-existing antibodypositive samples (54). Once positives are removed, the cut point should be calculated with an adequate quantity of remaining negative samples using standard approaches (i.e., 95th percentile) (29,55).…”

Utility of a Bayesian Mathematical Model to Predict the Impact of Immunogenicity on Pharmacokinetics of Therapeutic Proteins

“…The influence of high levels of TP limit detection of ADA, and high levels of ADA interfere with accurate measurement of TP. In this study, we utilized specific and sensitive assays for the bioanalytical measurements of PK and ADA levels that have minimal interference from matrix associated factors using the approach of integrating the Bfree^and Btotal^TP detections (Thway et al (4,22,23)). Further accuracy of the ADA and TP measurements requires a comprehensive evaluation of interference due to circulating ligands (soluble form or shed form of membrane receptors), matrix associated factors like excess TP or ADA, biodegraded or transformed fragments as in fusion proteins and small peptides or toxins as in antibody drug conjugates (24,25).…”