Antibody–drug conjugates: from efficacy testing to bioassay evaluation in modern drug development

Antibody-drug conjugates (ADCs) have emerged as one of the fastest-growing therapeutic modalities in oncology and are expanding in other disease areas as well, with 15 FDA-approved ADCs and over 250 drugs in different stages of development. The fact that they are a multicomponent modality must be considered when designing preclinical programs and, ideally, when predictive biomarkers are identified early on to assess efficacy, specificity, and safety. In parallel, bioassays for lot release testing in a good manufacturing practice (GMP) environment have to be developed that are reflective of the mechanism of action and that take the multicomponent character of the ADC into account.