The chicken embryo : An alternative preclinical model in oncology

For therapeutic purposes, the development of new anti-cancer drugs requires their evaluation in terms of activity, cytotoxicity and pharmacokinetics. The candidate drugs are tested in vitro on cell lines and primary cells isolated from patients, and in vivo, often, using xenografts in immuno-compromised mice. In recent years, administrative constraints have become increasingly stringent and the 3R rule (reduce, refine, replace) requires the elaboration of alternative models capable to replace mouse models or at least to limit their use. Among them, xenograft on chick embryo chorioallantoic membrane (CAM assay) seems particularly efficient. It makes it possible to monitor and quantify tumor growth and tumor-associated parameters such as neoangiogenesis, invasion and migration. It allows the screening of drugs effective both on tumor cells and their microenvironment. Finally, the model seems adapted to the development of personalized medicine to which current research in cancerology is tending. In this context, this review focuses on the technique itself and its advantages.