Fundamental properties and principal areas of focus in antibody-drug conjugates formulation development

Antibody-drug conjugates (ADCs) have emerged as a rapidly expanding class of therapeutics driven by their superior specificity and clinical efficacy. 14 out of 16 commercially approved ADCs are formulated as lyophilized forms because ADC is generally considered to be less stable than unmodified antibody. The formulation development for ADCs, particularly liquid formulation, presents unique challenges due to their intricate structural complexity, physicochemical properties, and degradation pathways. This review provides the first comprehensive analysis of formulation strategies employed in commercial ADCs. Furthermore, this review discusses the key areas of focus for ADCs throughout the formulation development workflow, spanning from the initial formulation development to the final stage of drug product manufacturing. In addition, we identify and analyze the distinctive technical challenges in ADC formulation development compared to unconjugated antibody, while proposing potential solutions to these challenges. Finally, we offer strategic perspectives on future directions in ADC formulation development to advance this promising therapeutic modality. Statement of Significance: This article comprehensively reviews and summarizes the formulations of commercial antibody-drug conjugates (ADCs) for the first time. The discussion extends to essential factors in drug product manufacturing and logistics processes. Additionally, the unique technical challenges of ADC formulation development compared to unconjugated antibody and the corresponding solutions are elucidated.