Oncolytic virus

An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by lysis, they release new infectious virus particles to help destroy the remaining tumour. Oncolytic viruses are thought not only to cause direct destruction of the tumour cells, but also to stimulate host anti-tumour immune responses.The potential of viruses as anti-cancer agents was first realised in the early twentieth century, although coordinated research efforts did not begin until the 1960s. A number of viruses including adenovirus, reovirus, measles, herpes simplex, Newcastle disease virus and vaccinia have now been clinically tested as oncolytic agents. Most current oncolytic viruses are engineered for tumour selectivity, although there are naturally occurring examples such as reovirus and the SVV-001 Seneca Valley virus, resulting in clinical trials.As of 2011, only limited human trials had been performed.Nevertheless, the drug talimogene laherparepvec (OncoVex, T-VEC) recently (Jan 2012) reported the first positive interim Phase III clinical trial results for an oncolytic virus, making it likely that it will also be the first one approved for use (for the treatment of advanced melanoma). However, skeptics have questioned the clinical relevance of this interim data citing that the awaited overall survival data will be the final judgement and that it is likely that patient benefit will be maximised in combination with other therapies, which this trial did not test. 2015 update: In a combined decision, members of the FDA’s Oncologic Drugs Advisory Committee (ODAC) and Cellular, Tissue and Gene Therapies Advisory Committee (CTGTAC) voted 22-1 to recommend approval of the oncolytic immunotherapy talimogene laherparepvec (T-VEC) as a treatment for patients with advanced melanoma. A final approval decision from the FDA is scheduled by October 27, 2015. Approved in Latvia oncolytic virus RIGVIR was registered in Georgia in February 2015. Melanoma Research published new data on RIGVIR efficacy, showing that early stage melanoma patients treated with oncolytic virus RIGVIR had 4.39–6.57-fold lower mortality than those, who according to melanoma treatment guidelines did not receive virotherapy and were only observed.