PHILADELPHIA -- Researchers have found a way to activate Epstein-Barr viruses inside tumors as a way to identify patients whose infection can then be manipulated to destroy their tumors. They say this strategy could offer a novel way of treating many cancers associated with Epstein-Barr, including at least four different types of lymphoma and nasopharyngeal and gastric cancers.
In the March 1 issue of Clinical Cancer Research, a team of radiologists and oncologists from Johns Hopkins Medical Institutions describe how they used two agents already on the market − one of which is the multiple myeloma drug Velcade − to light up tumor viruses on a gamma camera. The technique is the first in the new field of in vivo molecular-genetic imaging that doesn't require transfecting tumors with a "reporter" gene, the scientists say.
"The beauty of this is that you don't have to introduce any reporter genes into the tumor because they are already there," says radiologist Martin G. Pomper, M.D., Ph.D. "This is the only example we know of where it is possible to image activated endogenous gene expression without having to transfect cells."
A variety of blood and solid cancers are more likely to occur in people who have been infected with the Epstein-Barr virus (EBV), but not everyone with these cancers has such infections. For those who do, researchers, such as Hopkins oncologist and co-author Richard F. Ambinder, M.D., Ph.D., have been working on ways to activate the reproductive, or "lytic" cycle, within the virus to make it replicate within the tumor cell. When enough viral particles are produced, the tumor will burst, releasing the virus. In animal experiments, this experimental therapy, called lytic induction therapy, results in tumor death.
As the first step in this study, researchers screened a wide variety of drugs to see if any of them could reawaken the virus. They were fortunate in that one of the genes that is expre
Contact: Greg Lester
American Association for Cancer Research