Viral Therapies For Cancer
Herpes is not something you want to get. Chickenpox, shingles, cold sores…all are caused by a virus from the herpes family.
In virologist Fengshun Ye’s lab at Case Western Reserve University, he studies a particularly nasty form of herpes. "The virus that I’m working on is a herpes virus that can induce tumor in immune-compromised people...It is a bad bug."
Bad bug, yes. Bad family of bugs. But researchers at Ohio State University’s Comprehensive Cancer Center James think they can harness the genetic properties of the virus to help fight a stubborn cancer.
"A lot of cancers have seen improvement. Pancreatic cancer has not. So it remains a significant challenge," says Dr. Tanios Bekaii-Saab, an oncologist with the center who specializes in pancreatic cancer research. He says this cancer is hard because it often presents at late stages and resists the usual arsenal of chemotherapy and radiation. The tumor cells are crafty. "They surround themselves by a fortress of scar tissues and inflammatory cells, etc. So literally they build a fortress around themselves that makes it almost impenetrable."
But what’s really troublesome are the pancreatic tumor cells that doctors can’t see, says Saab. These are the wandering foot soldiers that will travel through the bloodstream and implant in the liver, the lungs, other parts of the body, and eventually cause another tumor to crop up. "Most patients die from these cancer cells that we do not see," he says.
This makes pancreatic cancer a prime target for new therapies that aim to wake up the immune system and make it able to find and kill these wandering cancer cells. And here’s where the herpes virus comes into play.
In a phase two clinical trial this April, Saab will test whether the addition of a herpes-like virus to the standard battery of cancer treatments can more effectively kill pancreatic cancer cells. He’ll inject a re-engineered virus into the patient’s tumor that will make the tumor cells look like herpes. "So essentially now the tumor cell is expressing, is sounding, more like a herpes cell," he says.
Then, he’ll inject a known antiviral herpes drug—think Valtrex—into the tumor and that drug will kill the tumor cells because it thinks they’re herpes. "It’s using gimmickry. You’re fooling the system for good reasons…You’re telling them that hey you know there is now something that looks like a herpes but is a cancer cell but who cares because you get there, you get activated, and you kill the cancer cell," he says.
Saab hopes this triggers an immune response. Normally, cancer cells outsmart the immune system. But with the herpes-marker, they become huntable. "It’s almost like awakening this giant, the immune system, that goes and just gobbles the rest of the cancer cells. That’s at least our hope," he says.
Dr. Stan Gerson, Director of the Case Comprehensive Cancer Center in Cleveland, says viruses are the most exciting area in development of cancer treatment today. He’s eager for results from several ongoing clinical trials that test different types of viral therapies for cancer. "They are powerful biological materials. We’re trying to figure out how we can harness them so we can safely give them to cancer patients," he says.
There are no FDA-approved therapies of this kind on the market in the US yet. Gerson expects within 3-5 years, researchers will have a good grasp of the effectiveness of viral therapies for cancer.
And for people with pancreatic cancer, and other stubborn and deadly cancers, that sort of new therapy can’t come soon enough.