Sunday, April 10, 2005
Killer Application
Neurosurgeons at Ohio State University have designed a killer virus that can slay brain tumor cells. The virus is a genetically altered herpes simplex virus that infects and reproduces only in malignant glioma cells and kills them, leaving other cells and tissues unharmed.
Malignant gliomas are fatal, progressive cancers in the brain. The average survival following diagnosis is about a year, said E. Antonio Chiocca, professor and chairman of neurological surgery at The Ohio State University Medical Center. They are usually treated using surgery, chemotherapy and radiation.
Chiocca engineered the killer virus to attack only cells that make a protein called nestin. The protein is produced by malignant glioma.
The researchers tested the virus in mice with implanted human gliomas. In one set of experiments, the researchers gave the virus to the mice early, seven days after implanting the tumors. Untreated mice lived for 21 days after tumor implantation. Eight of 10 mice treated with the virus survived 90 days after implantation. Two of 10 mice treated with a control virus survived 90 days.
Using the virus as a viable cancer therapy is still years away, though. "This is a preliminary study," said Chiocca. "This virus cannot yet be used in humans. To go from animal studies to human studies is a very long process, especially for a treatment that uses viruses."
This is not the first time neurosurgeons used the herpes virus to treat cancer. In 1992, Kenneth Culver, an oncology researcher at the National Cancer Institute, injected a modified retrovirus carrying a gene from the herpes virus directly into the brain tumors of mice and later humans. Soon, the tumors started expressing the herpes gene. Matt Ridley writes in Genome that "by then the cunning Dr. Culver was treating the patient with drugs for herpes and the drugs attacked the tumors. It seemed to work on the first patient, but on four of the next five it failed."
Malignant gliomas are fatal, progressive cancers in the brain. The average survival following diagnosis is about a year, said E. Antonio Chiocca, professor and chairman of neurological surgery at The Ohio State University Medical Center. They are usually treated using surgery, chemotherapy and radiation.
Chiocca engineered the killer virus to attack only cells that make a protein called nestin. The protein is produced by malignant glioma.
The researchers tested the virus in mice with implanted human gliomas. In one set of experiments, the researchers gave the virus to the mice early, seven days after implanting the tumors. Untreated mice lived for 21 days after tumor implantation. Eight of 10 mice treated with the virus survived 90 days after implantation. Two of 10 mice treated with a control virus survived 90 days.
Using the virus as a viable cancer therapy is still years away, though. "This is a preliminary study," said Chiocca. "This virus cannot yet be used in humans. To go from animal studies to human studies is a very long process, especially for a treatment that uses viruses."
This is not the first time neurosurgeons used the herpes virus to treat cancer. In 1992, Kenneth Culver, an oncology researcher at the National Cancer Institute, injected a modified retrovirus carrying a gene from the herpes virus directly into the brain tumors of mice and later humans. Soon, the tumors started expressing the herpes gene. Matt Ridley writes in Genome that "by then the cunning Dr. Culver was treating the patient with drugs for herpes and the drugs attacked the tumors. It seemed to work on the first patient, but on four of the next five it failed."
