Molecular theranostics for cancer therapy

In current cancer-related research program, theranostic systems are gaining ever-increasing attention owing to their unique offered package of advantages like imaging capability, therapeutic utility, and potential in understanding the diagnosis, staging, and treatment progress. In this book chapter, with a brief introduction about the concept of theranostic and its utilization to achieve cancer-specific imaging and therapy, we have covered the various strategies to prepare systems as mentioned above through proper choice of targeting ligands, cleavable chemical linkers, and chemotherapeutic drugs. Once internalized into cancer cells, these reaction-based systems get activated through cellular entities like reactive oxygen species, thiols, enzymes (elevated levels in the cancerous environment), acidic pH, and hypoxia (a physiological feature of cancer). Besides, the theranostic systems activated through external stimulus (light) are also explained. Further, in systems with drugs lacking inherent fluorescence property, additional reporters are used to serving the purpose. The current book chapter will help to understand the role of cancer-targeted reaction-based molecular theranostic systems in their drug activation mechanisms and future drug development efforts.