From Technology Review.
Biomedicine Engineered Viruses Selectively Kill Cancer Cells: The experimental therapy could ultimately serve as a seek-and-destroy treatment for metastatic cancer.
Wednesday, August 31, 2011 By Alla Katsnelson.
A single injection of a virus that has been genetically engineered to kill cancer cells can reliably infect tumors and leave healthy tissue unharmed, according to an early stage trial of 23 patients with metastatic cancers. The findings help lay the groundwork for a new type of cancer medicine using cancer-killing viruses.
Researchers injected different doses of the virus into patients with different types of metastatic cancers. After eight to 10 days, they biopsied tumor tissue from each patient and found that the virus was replicating itself in the tumors of seven of the eight patients who had received the highest dose, with no serious side effects. Several weeks after the injection, tumors in about half of the patients seemed to stop growing, and shrunk in one patient. The study is published today in the journal Nature.
While the study is not the first to test a cancer-killing viral therapy, it is the first to thoroughly document the behavior of the virus in patients’ biopsy tissue. The results confirm that viruses can be used to selectively target these cells.
One reason tumors can grow unchecked is that they suppress the immune system. However, this also makes tumor cells more susceptible to viruses, which replicate inside the infected cell until it bursts. Physicians have known for more than a century that viral infection slows tumor growth, and in recent years they’ve used molecular biology techniques to reëngineer more effective cancer-killing viruses.
Most such viruses now in trials are injected directly into the tumor. But what researchers really need is a therapy that could be injected into the bloodstream and seek out metastasized cancer cells throughout the body, says David Kirn, chief executive officer at Jennerex, the San Francisco-based biotech company that funded the study.
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