Application of Oncolytic Viruses for Cure of Colorectal Cancer

Colorectal cancer is one of the most commonly diagnosed and lethal cancers worldwide. It is the resultant of multistep processes caused by the accumulation of genetic/epigenetic aberrations. The different therapeutic strategies like radiotherapy, chemotherapy and surgery, used individually or in different combinations, do not remove tumors or their progression all the time. Besides, these procedures involve surrounding cells and tissues. In case of surgery, which is possible only before metastasis, even a single cancer cell left out during surgery, cause further cancer. Focus has been laid in developing agents that could specifically target the cancer cells and leave out the remaining normal cells. This also attempt at total recovery. This was how the focus was laid on viral agents. Over the last two decades, due to various advancements in molecular biology, virotherapy has seen various developments. A special class of viruses called oncolytic viruses have been used as a therapeutic strategy against cancer. These agents have various inherent and engineered factors like enhanced tissue tropism, thereby providing high selectivity; armed with transgenes to deliver therapeutic genes and to perform tumor selective replication, all these factors proving them improved and evolved mechanisms, when compared with other cancer therapeutics. These oncolytic viruses provide greater protection in association with herbal remedies. The purpose of this paper is to provide a detailed account of some of the current observations, developments and insights made in the field of oncolytic virotherapy for targeting colorectal cancer cells. A panel of five oncolytic viruses i.e. adenovirus, herpes virus, reovirus, vaccinia virus and new castle disease virus that are under clinical studies for targeting colorectal cancer cells have been discussed.