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Cold sore virus shows promise against colorectal cancer
Source: (cancerfacts.com)
Monday, June 06, 2005
BUDAPEST, Hungary – June 6, 2005 – A single injection of a modified cold sore virus has shown promise as a treatment for patients with colorectal cancer that has spread to the liver, according to preliminary results reported today at the 2nd European Society for Medical Oncology (ESMO) Scientific & Educational Conference (ESEC) in Budapest, Hungary.
In an early stage study designed to test safety, Dr. Nancy Kemeny from Memorial Sloan-Kettering Cancer Center in New York, and colleagues tested a genetically modified version of the herpes simplex virus that causes cold sores. These modified viruses, called NV1020, selectively kill cancer cells while sparing normal tissue and are considered a promising new strategy to treat tumors. They have already been shown to be effective against chemotherapy-resistant cancers in preclinical studies.
"Our primary aim in this study was to test the safety of the virus," Dr. Kemeny said in a prepared statement. "We were pleased to see that the virus could be administered safely in the hepatic artery without significant effects on the normal liver function."
The test involved 12 patients with colorectal cancer, which was not responding to chemotherapy and had spread to the liver. The scientists tested increasing doses of NV1020 delivered via a single 10-minute infusion into an artery. Treatment was followed by regional chemotherapy.
Patients in the study generally experienced mild or moderate side effects associated with the treatment, although three patients experienced self-limiting serious adverse events the researchers considered possibly or probably related to NV1020. These events comprised a temporary increase of gamma-glutamyl transpeptidase--a sign of liver disease--12 hours after treatment in a patient with a history of hepatitis, a case of gastroenteritis, and a case of mild leukocytosis considered due to a respiratory infection.
None of the patients showed any signs of herpes infection; the virus was detected in just one saliva sample and two blood samples from one patient who received the highest dose but experienced no symptoms of infection with the herpes virus.
So far, the overall median survival time of the 12 patients is 23 months with one patient still alive at 30 months post therapy. While that is an improvement in survival, Kemeny says the study is not designed to show effectiveness. Patients are also being treated with chemotherapy after the viral therapy so it is not possible to attribute the improvement to the viral therapy by itself.
"These results are very promising," Kemeny says. "The median survival time we saw among our patients was higher than you might expect among this group of patients. However, all were treated with hepatic arterial therapy and systemic therapy after the virus therapy."
The next step for the investigators is to use multiple doses of the virus since there are preclinical data to indicate that herpes oncolytic viruses work best when administered in multiple doses.
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