Brain cancer, also known as glioblastoma, are the last two words any patient wants to hear from their doctor. Patients who have received this diagnosis have likened it to a death sentence. Oddly enough, what was also considered a death sentence 50 years ago could end up giving brain cancer patients a fighting shot. Researchers from the Preston Robert Tisch Brain Tumor Center at Duke University have re-engineered the polio virus to cure brain tumors by removing a key genetic sequence.
Polio is an infectious disease caused by a virus that often results in irreversible paralysis and death. Following a global effort to eradicate the disease, the number of polio cases around the world has decreased from an estimated 350,000 cases in 1988 to 416 reported cases in 2013.
So cancers, all human cancers, they develop a shield or shroud of protective measures that make them invisible to the immune system. And this is precisely what we try to reverse with our virus. So by infecting the tumor, we are actually removing this protective shield. And telling the— enabling the immune system to come in and attack ,” Dr. Matthias Gromeier, a professor of neurosurgery, molecular genetics, and microbiology at Duke, told CBS’s 60 Minutes.
Gromeier, who has been working on the polio-virus project for 25 years, and his colleagues are currently injecting their genetically engineered polio virus, dubbed PVS-RIPO, into brain tumors of human patients. While using viruses such as HIV, smallpox, and measles to treat cancer is nothing new, the research team decided to throw their hat in the ring with polio. Luckily enough, they soon found that the virus is capable of seeking and attaching itself to a receptor found on the surface of almost every solid tumor.
Through clinical trials on both primate and human subjects, the research team discovered that PVS-RIPO was not only effective in releasing toxins that poison cancer cells, but it is also incapable of reproducing in normal cells. Due to the success of clinical trials, they hope to further their research by examining the effect PVS-RIPO has on other potentially fatal types of cancer, including breast, prostate, lung, colon, and pancreatic cancers.
Despite promising results from PVS-RIPO clinical trials, Duke scientists still have one hurdle to overcome: approval from the Food and Drug Administration (FDA). Not surprisingly, the FDA is very cautious when it comes to granting even limited approval of a treatment derived from a deadly disease. However, the FDA approved human trials in 2011 after seven years of safety studies. The FDA expects to make a decision on granting Gromeier and his team “breakthrough status” in around a year.
The idea of using viruses for cancer, on the other hand, has been there for over a hundred years, and it’s always been very interesting but no one had the technology to do it or knew how. Dr. Mattias Gromeier figured out that polio virus has this ability to attach to any solid tumor cancer cell—lung, breast, brain, prostate. The problem is that polio can also attach to neurons which is how people develop the polio disease. So he removed the toxic part that infected normal neurons, replaced it with the cold virus and kept only the part that attached to cancer cells. That’s why the modified virus is benign, but when we inject the modified polio virus directly into the tumor, it will infect a few of the cancer cells. The polio virus dies very rapidly, but it wakes up the immune system, making the immune system think polio is around and attacking the cancer cells,” says neuro-oncologist Dr. Annick Desjardins, one of the main physicians of the study.
So far, there were 22 patients that have undergone this therapy, 11 have died and 2 have been declared cancer-free. But did the treatment overall prolong life by significant amount? Dr. Annick Desjardins says,
Our trials are for patients with glioblastoma that has returned after treatment or surgery, so the fact that we have patients living now—three years after they were treated with the new therapy, three years since they’ve had a recurrence—it’s pretty amazing. We have patients that remain alive longer than the nine months we would have expected. But at this stage of clinical trials, the goal isn’t to look for the survival of the patient, because we’re really looking at the safety. The two patients that have done really well are encouraging for the others, and pushing us to find the right dose.”
via Duke Chronicle, CBS News and Medical Daily