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A genetically modified polio virus has improved the long-term survival of patients with a lethal-type brain tumor, according to the results of an early-stage clinical trial released Tuesday.
Twenty-one percent of patients treated with the virus – all with recurrent disease – were alive after three years, compared with only 4% of those who had undergone standard chemotherapy.
The trial at the Duke Cancer Institute involved patients with glioblastoma, the kind of tumor that Senator John McCain, R-Ariz., Is fighting. The findings were published online in the New England Journal of Medicine and presented Tuesday at an international conference on brain tumors in Norway.
Glioblastoma, a difficult-to-treat disease that is the most common of all malignant brain tumors, can cause seizures, headaches, blurred vision, and confusion. Even with aggressive treatment, newly diagnosed individuals usually survive less than 20 months, while those who reoffend usually die in less than one year.
Duke researchers opened the Phase 1 trial in 2012 to test the safety of the modified virus treatment and try to determine the right dose. After the surgeons implanted a catheter in each patient's brain, a small amount of a genetically modified form of the polio virus was infused directly into the tumor. The virus is designed to target tumor cells and trigger an immune system response.
The approach was the focus of widespread attention in 2015 while it was covered by the "60-minute" CBS program. The first participant in the trial was a nursing student who married and became a nurse, according to Duke representatives.
Tuesday's results were well received by experts who were not involved in the study. Still, these scientists strongly insisted on caution, saying that it was too early, and the number of patients in the trial too little, to find out how effective the approach is for glioblastoma .
The treatment of polio is one of many "oncolytic viruses" studied as anticancer agents. While researchers have long regarded these viruses as potential tools for directly killing cancer, they now suspect that viruses could be more effective at marshaling the body's immune system against malignant tumors, according to the National Cancer Institute.
Duke researchers said that the median survival of 61 patients in the study was 12.5 months, compared to 11.3 months for the "historical control group." This latter group of patients, used for comparison, was treated earlier with standard chemotherapy. met the criteria for testing the polio virus.
A subset of patients who received the treatment and who survived for at least two years received a much larger boost.
Debra Puffer, a 61-year-old resident of Rome, N.Y., was diagnosed with glioblastoma in 2014 and was treated with surgery, chemo and radiotherapy. When the cancer returned, she received treatment for the polio virus in Duke and remained two and a half years without recurrence. When the cancer came back again, she received a "booster" infusion of the polio virus last August.
She ended up in the hospital with serious side effects. But now, "everything looks a lot better," including her brain scans, she says. "I'm enjoying my summer."
Annick Desjardins, a Duke neurologist who is one of the main authors of the study, said the treatment of the polio virus seemed similar to that of other immunotherapies in that the majority of patients treated did not answer. However, those who mount an "active immune response" have the real possibility of becoming long-term survivors, she said.
In an attempt to increase the percentage of these responders, scientists have opened a Phase 2 trial at Duke and three other medical centers to test the polio virus treatment plus a chemotherapy drug, against just the virus. Researchers are also planning trials for breast cancer and melanoma.
Deepa Subramaniam, director of the Brain Tumor Center at Lombardi Comprehensive Cancer Center in Georgetown, described the results as "very interesting, enough reasons to continue." But she noted that it was "a very early phase trial" and that the treatment.
John de Groot, neuro-oncologist at the MD Anderson Cancer Center, described the study as "good science" but said the effectiveness of the therapy needed to be tested in a much larger number of patients and in many medical centers. He and Subramaniam both questioned the use of a "historical control group" rather than a real group. Subramaniam said it was "a sub-optimal way to compare" the results between patients receiving experimental treatment and those receiving standard treatment.
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