Preclinical Non-invasive Imaging in Cancer Research and Drug Discovery: An Overview

The increased understanding of complex biological processes in cancer initiation and progression has proportionately increased new anticancer drug development which is presently the top priority research field. The process of drug discovery and development is expensive, tedious, and unpredictable. Several steps are involved in this process, which requires strong multidisciplinary interaction. The duration of the procedure depends upon the validation of each step. Current data shows that out of the 10,000 newly screened compounds, only 250 enter preclinical testing and 5 enter clinical phase. However, only one compound gets regulatory approval. The percentage of success in developing a drug is very low, in spite of huge time spent and financial investments. Therefore, it is utmost important to refine every step of the drug development process so as to precisely evaluate the new compounds. The process of drug development consists of various phases like absorption, distribution, metabolism and excretion. All these phases can be precisely studied using several advanced tools and one such tool is non-invasive preclinical imaging. This chapter deals with various preclinical imaging modalities having huge potential in anticancer drug discovery. The imaging modalities discussed in details are positron emission tomography (PET), single photon emission computed tomography (SPECT), computed tomography (CT), optical, ultrasound and photoacoustic (US-PA) and spectral imaging. These modalities are complimentary to each other and need to be applied on the basis of information to be gathered. The common study/imaging protocol used in anticancer drug development has been mentioned with appropriate image data. The modalities such as photoacoustic and spectral imaging have huge potential for clinical applications due to their potential to characterise tissue and underlying pathophysiological differences.