Melanoma may be less common than other types of skin cancer, but it is also the most serious. As researchers look for new ways to extend the survival rates of those with advanced cases of this life-threatening disease, their focus centers on a new generation of virus-based drugs that have shown benefits in cancer trials. Among the most notable of these drugs is Talimogene Laherparepvec (T-VEC), which has shown great promise as a first-line treatment in the fight against metastatic melanoma. T-VEC is a genetically modified form of the herpes virus, which multiplies in cancer cells and destroys them by bursting them open from within. Because normal cells destroy T-VEC before it can cause damage, side effects are minimal. In a study involving 163 patients with stage three and four melanoma, those treated with T-VEC lived, on average, nearly twice as long (41 months) as those in the control group (21.5 months).