The development and manufacture of antibody-drug conjugates (ADCs) requires a series of complex steps. ADC manufacturers must comply with guidelines for both the small-molecule linker-drug and the monoclonal antibody (MAb). The authors describe their company’s development of its lead ADC product. They review process decisions, including the issues that factored into their selection of single-use systems, manufacturing challenges (differences between ADCs and MAbs), and testing methodologies for extractables and leachables. Synthon began as a small-molecule generics company in 1991. During…