June 5, 2008 -- A novel drug that launches a viral attack within cancer cells appears to improve survival in patients battling terminal liver cancer, according to a report published in Lancet Oncology.
Results from a phase 1 trial involving patients with solid cancers that did not respond to traditional treatments show that injecting the drug JX-594 directly into a tumor leads to its destruction in most patients, allowing them to live longer.
JX-594 is part of an emerging class of anticancer drugs known as oncolytic viruses. Oncolytic viruses are viruses that are genetically engineered to selectively infect and kill cancer cells without harming healthy cells. Once injected into a tumor, the virus multiplies, infecting and killing other tumor cells in distant places in the body. The quest for better, targeted cancer therapies has fueled interest in oncolytic viruses in recent years, even though the concept of virotherapy has been around for nearly a century.
JX-594 is engineered using the same strain of poxvirus used in smallpoxvaccines.
For the current study, 14 patients with a variety of primary and metastatic liver cancers received gradually increased doses of JX-594 by injection every three weeks.
Prior to the study, each patient had failed all other treatment options and was considered terminal. However, treatment with JX-594 improved life expectancy in most study patients. Half of the patients survived twice as long as or longer than their original 3-4 month prognosis, and four patients survived for 11 to 18 months.
"We believe the findings reported here support future trials with JX-594 and other oncolytic poxviruses," write Byeong-Ho Park, MD, of the Dong-A University College of Medicine in Busan, South Korea, and colleagues.
The drug appears safe and well tolerated. The most common side effects were mild-to-moderate flu-like symptoms.
A phase II trial is under way for JX-594 in liver cancer in the U.S., Canada, and South Korea.