ABSTRACT
Animal models that are used for biological assessment in drug development typically represent advanced or even end-stage disease and oen require sacrice of the animal for analysis. In the absence of imaging tools, the analyses performed require tissue sampling and time-consuming cellular or biochemical assays that only provide a snapshot of the overall disease course even when performed on large numbers of animals. erefore, one must consider the limitations of the data that result from conventional animal protocols that employ ex vivo assays, which are constrained by sample size, limited to a small number of selected time points, and performed in the absence of intact organ systems. In cancer models, tumors had been grown at supercial sites for easy assessment of tumor volume, but these models likely do not represent human disease. e use of such models is likely the reason most drugs fail in clinical trials. A major problem in drug development is that the animal models used for a given therapy are oen set up with a target that is likely to demonstrate the greatest ecacy using an outcome measure that is readily assessed. is may bias the model in favor of the therapy, and may not be predictive of the complex drug-target interactions in humans. One oen hears that we have cured cancer in mice, but cannot treat human cancers. We cannot develop eective drugs for humans by aiming at easy targets in mice and hard targets in the clinic. Our animal models need to accurately represent the complexity of human diseases.
