Cancer imaging: Gene transcription-based imaging and therapeutic systems

Molecular-genetic imaging of cancer is in its infancy. Over the past decade gene reporter systems have been optimized in preclinical models and some have found their way into the clinic. The search is on to find the best combination of gene delivery vehicle and reporter imaging system that can be translated safely and quickly. The goal is to have a combination that can detect a wide variety of cancers with high sensitivity and specificity in a way that rivals the current clinical standard, positron emission tomography with [18F]fluorodeoxyglucose. To do so will require systemic delivery of reporter genes for the detection of micrometastases, and a nontoxic vector, whether viral or based on nanotechnology, to gain widespread acceptance by the oncology community. Merger of molecular-genetic imaging with gene therapy, a strategy that has been employed in the past, will likely be necessary for such imaging to reach widespread clinical use.

► Gene transcription-based imaging or molecular-genetic imaging has been increasingly used as a cancer diagnostic and therapeutic strategy for the last decade.
► Well-characterized reporter gene-imaging probe pairs can be utilized to image cancer of various tissue origins and subtypes.
► The majority of strategies have employed organ- or cell type-specific promoters to drive reporter gene expression in a cancer-specific manner.
► Promoters with universal selectivity for cancer such as the PEG-3 promoter can broaden the application potential of the gene-transcription-based imaging and therapy.