Past, present and future of drug conjugates for cancer therapy.

Drug conjugates have emerged as promising tumor-targeted cytotoxics with an improved therapeutic index compared to classical chemotherapeutics. Although traditionally based on antibody ligands, high-throughput screening methods, such as peptide display and DNA-encoded chemical libraries, have enabled the isolation of ultra-high-affinity small ligands and the generation of drug conjugates with better tumor-targeting performance. This Perspective examines the history, major clinical milestones and future of drug conjugates for cancer treatment. We also discuss a new wave of combination modalities, linker strategies, and the development of conjugates based on large and small delivery vehicles.