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Therapy Prolongs Life in Mice with Brain Tumors
Research in mice suggests that directly treating tumors with a particular immune system protein may fight a deadly form of brain cancer.
Scientists used a genetically modified virus to deliver the protein, interleukin-12 (IL-12), to glioma tumors in mice. They found that the animals that had the IL-12-carrying virus injected directly into tumors survived significantly longer than those given either the virus alone or saline solution.
The researchers speculate that the treatment was able to jump-start the body´s natural immune defenses against cancer--a defense that may normally be ineffective against glioma. Malignant glioma is an aggressive form of brain cancer that does not respond well to treatment. Many people with the disease die within a year of diagnosis.
IL-12 is known to stir tumor-fighting T cells into action, and has received much research attention as an anti-cancer agent. However, treatment with lab-created IL-12 has caused serious side effects in patients, and scientists are looking for ways to deliver a targeted dose of the protein directly to the cancer, possibly avoiding unwanted side effects.
In this study, mouse glioma tumors were injected with a harmless virus carrying genes for IL-12. Of 12 treated animals, 6 were alive 60 days later, compared with 1 of 10 that got only the virus and 1 of 10 given saline.
Dr. John S. Yu and colleagues at Cedars Sinai Medical Center in Los Angeles, California, reported the findings in a recent issue of Cancer Gene Therapy.
The researchers also found evidence that mice given the IL-12 gene had increased anti-tumor activity in T cells. They speculate that the normal suppression of such T-cell activity in the central nervous system may contribute to the immune system´s ineffectiveness against glioma.
"Intracranial IL-12 expression," Yu and colleagues write, "may overcome this local...suppression."
SOURCE: Cancer Gene Therapy 2001;8.