The herpes simplex virus (HSV) is something no one ever wants to be infected with. HSV-1 (which produces most cold sores) and HSV-2 (which leads to genital herpes infections) are contagious, incurable viruses found in almost all cultures across the world. They're easily transmitted between people and can evade the immune system by hiding within nerve cells. So it might perhaps strike you as odd that the United States’ Food and Drug Administration (FDA) has approved a first-of-its-kind drug that uses a modified version of the herpes virus to infiltrate and reduce the size of cancer tumors, as reported by the Guardian.

Imlygic, an injectable drug made by Amgen Inc., will be used on cancerous tumors – in this case, malignant melanoma (skin cancer) tumors that cannot be surgically removed. This drug will only be applied to patients with metastatic malignant melanomas, meaning that the cancer has begun to spread to other parts of the body, or “metastasize.” This advanced skin cancer is, to many with this affliction, a death sentence, with the 10-year survival rate being less than 10%. 

The new drug is injected directly into the tissue of the melanoma and uses the HSV-1 virus as a form of Trojan horse to slip into the cancerous cells to destroy them. When HSV-1 enters the human body, it targets specific host cells, using its own receptors to bind to the surface of the host cell membrane. Once it has a firm grip on the cell, an “entry pore” develops, allowing the virus to dispense its genetic material into the cell, which infiltrates the cell nucleus.

This then hijacks the host cell, forcing it to replicate the viral genetic code. These new viral particles are released when the host cell bursts, destroying it. This same method will be used by the modified HSV-1 virus to destroy the cancerous tumor cells. Not only that, but the presence of the virus within the tumor will elicit a response from the immune system, recruiting it to attack the tumor.

This drug will be the first time a virus has been approved for use for treating cancer. The FDA was quick to stress that although it was effective at shrinking melanoma tumors in 16% of patients – 14% more than those treated with conventional cancer drugs – for up to six months, it has not yet been shown to prolong the life of any patients. It also did not have any effect on melanomas that had metastasized to other internal organs.

Although dependent on the length of the treatment, a single course would cost $65,000 (£42,500); Amgen Inc. said that patients should be treated until there were no more tumors remaining. Despite the cost, it won’t make Amgen a huge profit.

[H/T: The Guardian]