Oncolytic virotherapy: Challenges and solutions.

Viruses as cancer therapies have attracted attention since the 19th century. Scientists observation that viruses can preferentially lyse cancer cells rather than healthy cells, created the field of oncolytic virology. Like other therapeutic strategies, oncolytic virotherapy has challenges, such as penetration into tumor bulk, anti-viral immune responses, off-target infection, adverse conditions in the tumor microenvironment, and the lack of specific predictive and therapeutic biomarkers. Whilst much progress has been made, as highlighted by the first Food and Drug Administration approval of an oncolytic virus talimogene laherparepvec (T-VEC) in 2015, addressing these issues remains a significant hurdle. Here we discuss different types of oncolytic viruses, their application in clinical trials, and finally challenges faced by the field of oncolytic virotherapy and strategies to overcome them.