Bioanalysis of Antibody–Drug Conjugates: American Association of Pharmaceutical Scientists Antibody–Drug Conjugate Working Group Position Paper

Abstract

Antibody-drug conjugates (ADCs) typically consist of a cytotoxic drug covalently bound to an antibody by a linker. These conjugates have the potential to substantially improve efficacy and reduce toxicity compared with cytotoxic small-molecule drugs. Since ADCs are generally complex heterogeneous mixtures of multiple species, these novel therapeutic products present unique bioanalytical challenges. The growing number of ADCs being developed across the industry suggests the need for alignment of the bioanalytical methods or approaches used to assess the multiple species and facilitate consistent interpretation of the bioanalytical data. With limited clinical data, the current strategies that can be used to provide insight into the relationship between the multiple species and the observed clinical safety and efficacy are still evolving. Considerations of the bioanalytical strategies for ADCs based on the current industry practices that take into account the complexity and heterogeneity of ADCs are discussed.

Absorption, Distribution, Metabolism, and Excretion Considerations for the Development of Antibody-Drug Conjugates

“…Each individual species of ADC is pharmacologically activity, with potentially distinct pharmacokinetics and intrinsic pharmacology and toxicity. Current technologies to measure antibodies and small molecules are limited in the extent they can be used to characterize ADCs in biologic matrices (Gorovits et al, 2013;Lin et al, 2013), but advancements have recently been made to measure intact ADCs in biologic matrices (Hengel et al, 2014). Selecting the analytes to measure to understand the pharmacodynamic and toxic effects of ADCs is a scientific and technical challenge.…”

Immunogenicity of Antibody Drug Conjugates: Bioanalytical Methods and Monitoring Strategy for a Novel Therapeutic Modality

“…The pharmacokinetics and pharmacology, toxicology, and bioanalytical strategies used for these ADCs have been reviewed (17)(18)(19)(20)(21)(22). Immunogenicity support strategies (and the resulting data) for these approved ADCs form the knowledge base on what is an expanding field (Table I illustrates the examples of published ADC immunogenicity information).…”

Antibody–Drug Conjugates as Cancer Therapeutics: Past, Present, and Future

“…39 Notwithstanding the complexities discussed above, the accepted consensus based on previous ADC experience is that the most useful parameters and information about E-R relationships can be derived by analysis of the ADC, total antibody, and/or unconjugated payload. 25,37 However, total antibody is typically analyzed in early clinical trials (for example, FIH) and subsequently dropped in later clinical studies because of strong correlation with ADC. Bioanalytical methods, including enzyme-linked immunosorbent assays and liquid chromatography-mass spectrometry, allowed for reliable insights into linker stability, TMDD, and E-R relationships.…”

“…The PK of an ADC is primarily driven by the carrier mAb backbone, 25,35 but the linker, payload, and DAR also impact ADC stability and PK. [36][37][38] For example, the hydrophobicity of the linkers conjugated to an anti-CD70 mAb impacted ADC clearance, half-life, and area under the concentration-time curve. 38 In addition, both distribution and elimination phases changed with linker hydrophobicity, indicating an overall change in ADC disposition.…”

“…Bioanalytical methods, including enzyme-linked immunosorbent assays and liquid chromatography-mass spectrometry, allowed for reliable insights into linker stability, TMDD, and E-R relationships. 37,40 In vivo ADC biodistribution is assessed during clinical trials using singlephoton emission computed tomography and positron emission tomography imaging. 41 DAR-sensitive or DAR-insensitive bioanalytical methods can be developed and need to be considered depending on the question being addressed.…”