UCSF

A functional approach to generate tumor-targeting human monoclonal antibodies is through selection of phage antibody display libraries directly on tumor cells. Although technically convenient, the use of cancer cell lines for the selection has limitations as those cell lines often undergo genetic and epigenetic changes during prolonged in vitro culture and alter their cell surface antigen expression profile. The key is to develop a technology that allows selection of phage antibody display libraries on tumor cells in situ residing in their natural tissue microenvironment. Laser capture microdissection (LCM) permits the precise procurement of tumor cells from human cancer patient tissue sections. Here, we describe a LCM-based method for selecting phage antibodies against tumor cells in situ using both fresh frozen and paraffin-embedded tissues. To restrict the selection to antibodies that bind internalizing epitopes, the method utilizes a polyclonal phage population pre-enriched for internalizing phage antibodies. The ability to recognize tumor cells in situ residing in their natural tissue microenvironment and to deliver payload intracellularly makes these LCM-selected antibodies attractive candidates for the development of targeted cancer therapeutics.