Editorial [Hot Topic: Molecular Imaging in Drug Development (Executive Editor: M. Kassiou) ]

Molecular imaging refers to the use of non-invasive imaging techniques to detect signals that originate from molecules, often in the form of an injected tracer, and observe their interaction with a specific cellular target in vivo. This technique is capable of measuring the biodistribution of minute concentrations of radio-labelled biomolecules in vivo and quantifying the molecular kinetic processes in which they participate. This technique can provide a wealth of information, which can facilitate the drug development process and the planning of therapy. This issue of Current Pharmaceutical Design highlights the capabilities of PET and SPECT in pre-clinical and clinical research and acknowledges the efforts from each contributor in putting this issue together. T.J. Wadas and co-workers [1] at the Mallinckrodt Institute of Radiology and the University of New Hampshire outline the use of copper isotopes in particular 64Cu in diagnostic imaging and radiotherapy. However, significant developments are required in the development of ligands that can form a stable complex with 64Cu for delivery into living systems. These advances are highlighted in this review. Y.S. Choe and K-H Lee [2] from the Samsung Medical Center review applications of targeted imaging of angiogenesis using molecular imaging and suitable radiotracers based on potential targets which include integrins, extracellular matrix, VEGF, activated endothelial cells and MMPs. Specific imaging of angiogenesis will help define the pathophysiology in living subjects and identify those patients likely to respond to antiangiogenic or angiogenic therapies and enable the efficacies of these therapies to be assessed. J. Lever [3] from the University of Missouri outlines the use of opioid receptors as drug targets and focuses on the status and use of radiotracers for imaging opioid receptors using molecular imaging. Selected studies are discussed to illustrate the power of molecular imaging for facilitating opioid drug discovery and development. T.L. Collier and co-workers [4] at Siemens Biomarker Solutions, Columbia University of Physicians and Surgeons and the University of Sydney outline the biological function and therapeutic potential of sigma receptors. Sigma receptors have recently been the target of drug development related to psychiatric disorders, cognitive enhancers, neuroprotective and antiamnesic actions. This review highlights what is known about these enigmatic sites and the use of molecular imaging in studying these receptors. References [1] Wadas TJ, Wong EH, Weisman GR, Anderson CJ. Copper Chelation Chemistry and Its Role in Copper Radiopharmaceuticals. Curr Pham Des 2007; 13(1): 3-16. [2] Choe YS, Lee K.-H. Targeted In Vivo Imaging of Angiogenesis: Present Status and Perspectives. Curr Pham Des 2007; 13(1): 17-31. [3] Lever JR. PET and SPECT Imaging of the Opioid System: Receptors, Radioligands and Avenues for Drug Discovery and Development. Curr Pham Des 2007; 13(1): 33-49. [4] Collier TL, Waterhouse RN, Kassiou M. Imaging Sigma Receptors: Applications in Drug Development. Curr Pham Des 2007; 13(1): 51-72.