Rise of Antibody-Drug Conjugates: The Present and Future

Antibody-drug conjugates (ADCs) embody a simple, but elegant, vision for cancer therapy-the delivery of a potent cytotoxic agent to tumor cells with minimal damage to normal cells-so-called smart chemo. Although there were significant challenges in achieving this milestone culminating in the first Food and Drug Administration approval in 2000, subsequent advancements in technology have led to rapid drug development with regulatory approvals for ADCs targeting a variety of tumor types. The most successful application for solid tumors has been in breast cancer, with ADCs becoming the standard of care across traditional human epidermal growth factor receptor 2 (HER2)+, hormone receptor+ (HR+) and triple-negative disease subtypes. Moreover, the improved features and gains in potency with the development of ADCs have expanded the treatment-eligible population to those with low/heterogeneous expression of the target antigen on the tumor with trastuzumab deruxtecan or in the case of sacituzumab govitecan, agnostic to target expression. Despite their antibody-directed homing, these novel agents come with their share of toxicities obligating appropriate patient selection and vigilant monitoring while on treatment. As more ADCs are included in the treatment armamentarium, mechanisms of resistance need to be studied and understood for optimal sequencing. Modifying the payload to use immune-stimulating agents or combination therapies with immunotherapy and other effective targeted therapies may further extend the utility of these agents in the treatment of solid tumors.