A Virus That Does More Good Than Harm

Vaccinia virus and radioactive isotope improve imaging and radiotherapy

(RxWiki News) For many people, viruses tend to be thought of as unwelcomed guests. For cancer patients, one virus may actually help pancreatic cancer recovery.

A new study examined the effects of an engineered vaccinia virus on pancreatic cancer. Researchers found that the virus could aid in non-invasive imaging and improve radiotherapy.

"Ask your oncologist about what imaging techniques are available for use.  "

Researchers at Memorial Sloan-Kettering Cancer Center and the Genelux Corporation studied the vaccinia virus (GLV-1h153) that had been modified. Using virotherapy, which alters viruses to make them fight cancer, the modified vaccinia virus was combined with radioactive iodine and applied to pancreatic cancer tumors. This combination not only improved imaging but helped kill the tumors.

Radioactive iodine can kill malignant tumors and is used for imaging because part of the energy it gives off is transmitted as gamma rays. These gamma rays can then be viewed by nuclear imaging techniques like Positron Emission Tomography (PET). With more ways to carry iodine, PET imaging is more effective because there is more radioactive iodine within the tumor.

The vaccinia virus has a history of helping scientists fight against disease. It was used and modified to help eradicate the variola virus, the causative agent of smallpox.

Radioactive iodine has been trickier for scientists because in small doses it can lead to cancer, but in higher doses can kill cancer. With these high doses though, there is an increased risk for side effects.

According to Dana Haddad, M.D., Ph.D, resident at the Mayo Clinic at Scotsdale, Arizona, researchers were concerned because the PET signal was declining after two weeks. Radioactive iodine, when in the body, has nowhere to go and stays in the area it was injected into. Since it is radioactive, it has a certain life span before it starts to decrease in radioactivity. The signal decrease was actually due to increased effectiveness, researchers discovered.

In low doses alone, the virus and iodine were not very effective in killing tumors, but when combined with the radioactive isotope those results improved significantly. The combined effectiveness meant the amount of radioactive iodine could be reduced, leading to less side effects.

The combined therapy could be helpful in the future for imaging techniques and fighting pancreatic cancer. According to Dr. Haddad, more research involving this virus is planned.

The modified virus could be used in clinical trials for tracking cancerous tumors, real-time monitoring of how effective a treatment is and determining how a treatment could be used for radiotherapy.

Findings from this study were presented at the Second AACR International Conference on Frontiers in Basic Cancer Research.

Research presented at meetings is considered preliminary until published in a peer-reviewed journal.

Review Date: 
October 17, 2011