Internalizing antibodies and targeted cancer therapy: direct selection from phage display libraries

Antibody internalization is required for the success of many targeted therapeutics, such as immunotoxins, immunoliposomes, antibody–drug conjugates and for the targeted delivery of genes or viral DNA into cells. Recently, it has become possible to directly select antibody fragments from phage display libraries for internalization into mammalian cells. Here we review the therapeutic applications of internalized antibodies and describe how phage display enables the isolation of internalizing antibodies to novel or known targets.