Herpes Virus Shows Early Promise for Advanced Skin Cancer
Feb. 15, 2001 -- When it causes a cold sore, the herpes simplex virus can be downright annoying. But when it's delivered to tumors, HSV could possibly be a lifesaver, suggest Scottish researchers in the Feb. 17 issue of The Lancet.
Rona M. MacKie, MD, and colleagues report that in three of five patients with advanced melanoma, the most serious form of skin cancer, injection of a mutant form of herpes simplex virus (that can't cause infection) killed off most of the tumor cells, and in one patient caused the raised tumor nodules to flatten completely.
In addition, the injections appeared to be safe and did not reactivate dormant herpes infections in the patients, all of whom had previously been infected with the virus.
Herpes simplex is a widespread virus that causes cold sores and fever blisters in some people who are infected with it. Herpes infections are generally not serious, but can be particularly dangerous for people with crippled immune systems who can't fight off such an infection, like the patients in the study, all of whom had undergone extensive chemotherapy for cancer, MacKie tells WebMD.
"What we've shown is that you can deliver [the herpes] virus to the site of tumor cells," she says. "But what we are now thinking about is how we get the virus to tumor cells in sites other than the [skin's] lumps and bumps, which is obviously easy."
In its more advanced stages, melanoma can spread to the liver and lung. "We need to find a way to get it to liver and lung as well," she says.
MacKie emphasizes that the study was a small trial designed only to test the safety of the therapy and not its effectiveness. All five patients enrolled in the study have since died of their disease. Nonetheless, the therapy is promising enough to warrant larger scale trials at higher doses, she tells WebMD.
The novel treatment approach exploits key features of both melanoma cells and the herpes virus. By an accident of birth, the skin cells (melanocytes) from which malignant melanoma develops are distantly related to nerve cells, because the skin cells are derived from the same source as the nervous system during fetal development.
Herpes simplex just happens to be a virus with a particular taste for nerve system cells, which could therefore make it a potent weapon against melanoma, the authors say.
"[Herpes simplex virus] actually has a predilection to [certain] nerves, and then once it's in those nerves, it [stays there for life], and then comes back down the nerve to [occasionally] give you a recurrent infection," explains Edouard Cantin, PhD, associate professor of neurovirology at City of Hope Medical Center in Duarte, Calif. Cantin was not involved in the study, but discussed with WebMD the potential therapeutic uses of herpes virus for treating melanoma.