Imaging in drug development with reporter mice

Drug development is a time consuming and costly process, and new molecules go through preclinical studies in a variety of experimental animals and different phases of clinical trials before the drug's developers apply for the Food and Drug Administration's approval. The arsenal of detection devices, identified biomarkers, labeled drugs, genetically encoded reporters and animal models is rapidly expanding, providing new approaches for pharmacokinetic and pharmacodynamic studies. In this scenario, molecular and functional imaging techniques can be very attractive, in that if applied since the initial stages of drug development can provide evidences of activity or unexpected toxicity, confirm the effect occurring on a specific target of new chemical entities and identify patients who are more likely to benefit, thus stopping earlier non promising projects and investing more time and money on specific promising ones, reducing the total cost and risk of drug development. in this review article the major strategies in which molecular imaging techniques are helping pharmacological research are reported. The approach choice, the features of the reporter animal, the imaging technique and the reporter gene are discussed evaluating pros and cons of drug labelling and of the use of animals, that express a reporter gene in any phase of the drug development process.