Antibody Drug Conjugate Analysis

What is antibody drug conjugate analysis and why is it critical for product development?

Antibody drug conjugate analysis presents a range of analytical and bioanalytical challenges, that must be addressed to support successful product development and registration. Antibody drug conjugates (ADCs) combine a mAb with a small-molecule drug or payload through a chemical linker. The inherent complexity of the mAb, together with the variability introduced through conjugation and drug loading, requires a range of complementary ADC analysis approaches to establish product quality, safety and efficacy.

ADC Characterization and Antibody Drug Conjugate Characterization Services

With over 30 years’ experience in ADC characterisation and bioanalysis, our laboratory experts have considerable knowledge of the evolving regulatory framework across different regions and the scientific background to this product class. Bringing quality and safety to life, our scientists engage with clients from all around the world, helping them to meet all regulatory expectations and specifications for successful drug substance and drug product release. From ADC analytical development support and bioanalytical services delivered from our GLP- GCP- and GMP- compliant laboratories to regulatory compliance and beyond, Intertek's services are delivered consistently with precision, pace and passion, enabling our global customers' antibody drug conjugate development programmes.

ADC Quantification and Bioanalysis Services for Preclinical and Clinical Studies

ADCs present unique bioanalytical challenges as they tend to be complex heterogeneous mixtures of multiple species with varying drug-to-antibody ratios (DARs). Combining the characteristics of both large and small molecules, ADCs often require a complementary range of analytical approaches. As an experienced antibody drug conjugate CRO, our bioanalytical laboratory teams apply diverse bioanalytical methods, including ligand-binding assays and LC-MS, to quantify relevant ADC species in serum or plasma supporting pharmacokinetic (PK) studies throughout drug development. 

Immunogenicity assessment is also an important component of clinical development. Our experts can develop fit-for-purpose strategies to evaluate immune responses to the ADC and its constituent components, applying sensitive immunoassays to support robust assessment of anti-drug antibodies and their potential impact on PK, safety and efficacy. Intertek provides complete bioanalytical capabilities for ADCs: 

• Quantitative bioanalytical assays for preclinical and clinical studies
• Total antibody assays
• Total conjugated ADC assays
• Unconjugated (free drug) assays
• Immunogenicity assessment including anti-drug antibody (ADA) assays 

ADC Analytical Development Services From Early Characterisation Through Release Testing

Regardless of the regulatory pathway, comprehensive ADC characterization and testing are required throughout ADC development. The complexity and heterogeneity of the mAb, together with variability introduced through linker-payload conjugation, require complementary analytical approaches. Our antibody drug conjugate testing teams develop phase-appropriate strategies to establish ADC identity and characterise key structural and conjugation-related attributes, including: 

• Identity and antibody drug conjugate structure – intact and subunit mass analysis, peptide mapping and sequencing  
• Drug loading – determination of average drug-to-antibody ratio (DAR) and distribution of individual drug-load species using DAR mass spectrometry
• Conjugation – identification and characterisation of ADC site specific conjugation  
• Molecular attributes – assessment of relevant post-translational modifications and other structural characteristics  
• Binding – assays to assess relevant antibody binding characteristics  

Our experts apply complementary techniques including mass spectrometry, liquid chromatography, electrophoresis and spectroscopy to provide insight into ADC structure, heterogeneity and drug loading. These antibody drug conjugate characterization data can inform phase-appropriate purity and impurity testing, stability assessment and comparability studies throughout development. 

Antibody Drug Conjugate Analysis for Purity, Aggregates and Impurities

We assess ADC purity using complementary analytical approaches, including SDS-PAGE, capillary gel electrophoresis, size-exclusion chromatography and charge-variant analysis. Orthogonal chromatographic and electrophoretic methods can be applied to characterise product-related variants and impurities, including aggregates, fragments and other relevant species, supporting the development of a comprehensive ADC purity and impurity profile. 

Antibody Drug Conjugate Testing for Stability and Structural Integrity

Our experts design and perform ADC stability assessment using chromatographic, electrophoretic and spectroscopic methods. Testing focuses on relevant quality attributes, including aggregation, fragmentation and other degradation pathways. Analytical approaches established for mAbs can often be applied or adapted for ADCs, alongside methods addressing conjugation-specific attributes. Structural techniques, including circular dichroism (CD), can also be used to assess higher-order structure and determine whether conjugation has affected antibody conformation. 

Antibody Drug Conjugate Characterization and Comparability Studies

Our laboratory experts conduct phase-appropriate comparability studies for both the mAb and ADC to evaluate product quality across toxicology, clinical and commercial batches, or following relevant manufacturing changes. Analytical packages can assess structural, physicochemical and functional attributes alongside ADC-specific characteristics, including drug loading and drug-load distribution, to support a robust assessment of comparability.