Tumor homing peptides as molecular probes for cancer therapeutics, diagnostics and theranostics

Cancer is one of the leading causes of mortality worldwide, with more than 10 million new cases each year. Despite the presence of several anticancer agents, cancer treatment is still not very effective. Main reasons behind this high mortality rate are the lack of screening tests for early diagnosis, and non-availability of tumor specific drug delivery system. Most of the current anticancer drugs are unable to differentiate between cancerous and normal cells, leading to systemic toxicity, and adverse side effects. In order to tackle this problem, a considerable progress has been made over the years to identify peptides, which specifically bind to the tumor cells, and tumor vasculature (tumor homing peptides). With the advances in phage display technology, and combinatorial libraries like one-bead one-compound library, several hundreds of tumor homing peptides, and their derivatives, which have potential to detect tumor in vivo, and deliver anticancer agents specifically to the tumor site, have been discovered. Currently, many tumor homing peptide-based therapies for cancer treatment and diagnosis are being tested in various phases of clinical trials. In this review, we have discussed the progress made so far in the identification of tumor homing peptides, and their applications in cancer therapeutics, diagnosis, and theranostics. In addition, a brief discussion on tumor homing peptide resource, and in silico designing of tumor homing peptides has also been provided.