Improving Oncolytic Herpes Simplex Virus

A steady decline in the overall number of deaths due to breast cancer since 1990 represents remarkable progress in early detection [1]. Survival rates are near 100% when the disease is localized; however, breast cancer patients that have distant metastases have a 5- year survival rate that is below 25% - a rate that has not changed over the years. There are few effective treatment options for patients with metastatic disease indicating that improved therapies are clearly needed. Emerging strategies utilizing a variety of oncolytic viral therapies have been described in the literature and clinical trials have been ongoing for many cancer types with mixed results [2]. The intent of an oncolytic virus is to complete multiple cycles of cell lysis and infection of adjacent cancer cells to eradicate a tumor while sparing normal cells. A particularly attractive oncolytic virus that has received recent attention is the attenuated oncolytic herpes simplex virus type 1 (oHSV) [3].