The medicinal chemistry of theragnostics, multimodality imaging and applications of nanotechnology in cancer.

Targeted imaging of cancer is crucial to modern-day cancer management. This review summarizes the current status and future prospects of targeted cancer imaging with MRI, PET, SPECT, CT, and optical imaging techniques. It describes various approaches of cancer imaging and therapy, based on targeting of integrins, somatostatin receptor, epidermal growth factor receptor (EGFR), Her-2/neu receptor, glucose transporter (GLUT), folate receptor, steroid receptor. It also discusses the applications of nanotechnology in imaging and therapy of cancer. Techniques for imaging of cancer in multiple modalities, using a single agent in a single session, have been developed, and this technique is known as 'multimodality imaging'. In order to develop target-specific imaging probes, various targeting ligands, such as small molecules, antibodies, peptides and aptamers have been used. These new imaging agents will help to develop cancer imaging probes that are highly target specific, biocompatible, have high sensitivity, give high signal to noise ratio, and have optimum pharmacokinetic and pharmacodynamic profiles. In another approach, novel agents have been synthesized, suitable for use in imaging as well as in therapy, and they are known as 'theragnostic (or theranostic) agents'. Multidisciplinary approaches and collaborative research efforts from chemists, biologists, biomedical engineers, pharmaceutical scientists, and medical doctors will lead to the discovery of clinically useful imaging and therapeutic agents that can diagnose, prevent, and cure cancer.