One class of the new generation of cancer therapies presently under development uses targeted viruses to kill cancer cells. Here is an example of the type: "BioVex Inc, a company developing new generation biologics for the treatment and prevention of cancer and infectious disease, announced today that the data from its completed Phase 2 clinical study ... [the therapy] is a first-in-class oncolytic, or cancer destroying virus, that works by replicating and spreading within solid tumors (leaving healthy cells unaffected), thereby causing cancer cell death and stimulating the immune system to destroy un-injected metastatic deposits. Both modes of action have been clearly validated in the clinic, where multiple patients with metastatic disease progressing at enrollment have been declared disease free. ... Previous clinical trials have enrolled patients with breast cancer, melanoma, head and neck cancer and pancreatic cancer, with indications of clinical activity being observed in each. The Company recently commenced a Phase 3 study in metastatic melanoma." Therapies with few side effects and even low rates of success against metastatic cancer are a big deal. The success rate will only improve with time, and is already far greater than that of any presently widespread treatment option.