Antibody-drug conjugates for cancer therapy: The technological and regulatory challenges of developing drug-biologic hybrids

Antibody-drug conjugates (ADCs) are a new class of therapeutic agents that combine the targeting ability of monoclonal antibodies (mAbs) with small molecule drugs. The combination of a mAb targeting a cancer-specific antigen with a cytotoxin has tremendous promise as a new type of targeted cancer therapy. Two ADCs have been approved and many more are in clinical development, suggesting that this new class of drugs is coming to the forefront. Because of their unique nature as biologic-small drug hybrids, ADCs are challenging to develop, from both the scientific and regulatory perspectives. This review discusses both these aspects in current practice, and surveys the current state of the art of ADC drug development.