A Virus That Kills Cancer
SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.
The holy grail of health care, arguably, is a cure for cancer. For decades we’ve relied on treatments like radiation therapy and chemotherapy, which don’t always work and can have some horrible side-effects. After all, chemotherapy was inspired by mustard gas around the time of World War I. But cancer cells are part of our own bodies so they are always with us, and our immune system recognizes them and kills them.
Sometimes the cancer grows and defends itself, that’s when we become sick with cancer. So a neat trick would be getting the body’s immune system to one-up these tumors and fight back. Right? That’s called Immunotherapy. How do you do make that work? To find out, I spoke with Dr. Annick Desjardins, Associate Professor of Neurology at Duke University Medical Center, who, along with a team lead by Dr. Matthias Gromeier are working on this.
The poliovirus will attach to every solid tumor cancer cell.
We’ve known that for a long time about our old enemy Polio, that it will cling to cancer. But how do we use this to our advantage? Well first you need to tame the virus. The Team at Duke did that by genetically modifying it, and giving it a cold . . . sort of.
We do know the receptor for the poliovirus is present on the solid tumor, so we decided that the first trial will be with a brain tumor patient. We took the Sabin vaccine . . .
Which contains live, though weakened, poliovirus . . .
. . . removed the part of the gene of the virus that is toxic to the gut and the nervous system, the spinal cord, and replaced it with the cold virus. So, we tricked the virus by making it think it’s complete, that it’s a whole virus, when in fact a part of it has been replaced with something else. We inject the modified poliovirus into the tumor. The modified poliovirus will infect a few of those glioblastoma cells, so the immune system thinks that it’s going to destroy polio and kill polio, when in fact what is there is the glioblastoma.
A glioblastoma is a type of tumor usually found in the brain. This process has been been used with varying success.
We treated our first patient in the beginning of 2012. It was a young woman that was diagnosed when she was 20 years old. Surgery, radiation. The tumor came back 9 months later. We do expect that the survival would have been less than one year after the tumor came back, so in January of 2012 we injected her with the poliovirus, and three years later there is absolutely no sign of cancer in her brain. We have a number of other patients that are also following behind. So far there is no sign of active tumor. There are some other patients where it didn’t work as well. Was it because of the dose? Was it because of the size of the tumor? Was it their immune system or the different treatments they were on? Did it interfere with the poliovirus? It’s possible, but it's all things we are looking in to.
The possibility of curing brain cancer is exciting. So what about other kinds of cancer?
We’re still at the phase that we’re looking at what is the optimal dose that will trigger enough immune response to wake up and to kill the tumor, but not so much that the immune system is too awake and becomes dangerous. Once we have looked into finding the right dose, we are thinking of moving into other types of cancer. Waking up the immune system is something we have worked on for many years. So it is very exciting for us. We also have to remember though, that we still need to be smart. We still need to be careful. Because every time that you have a new treatment, there is a curveball that shows up. When you bring a new treatment, you need to be aware that it is possible that the cancer will react in a way that it learns how to fight the treatment. That’s why even if, yes we are very positive, yes we are getting better and smarter, and understanding the immune system, we still need to give us the chance to understand it better. To do the research and do it right.