Smallpox Vaccine Takes on Cancer

Author:  Jiang Dennis
Date:  November 2007

The smallpox vaccine is back! But don't be alarmed, the smallpox disease is still eradicated. A joint research team from Stanford University and Jennerex Biotherapeutics, headed by Stephen Thorne, a virologist at the University of Pittsburgh, investigated into the smallpox vaccine's potential in eradicating tumors. Results published in October 2007 in the Journal of Clinical Investigation revealed that liver tumor growths in rabbits can be deterred or even reversed. These results suggest a very optimistic outlook in the vaccine's application as an anti-cancer treatment in humans.

The new smallpox vaccine, also known as vaccinia, is genetically engineered and more sophisticated than the original vaccine in its molecular activity. The researchers first removed two genes from the vaccinia virus to prevent its growth inside normal cells. This means that the virus will only infect and kill tumor cells. The researchers then introduced a new gene into the virus that causes it to produce chemicals that attract white blood cells. The white blood cells will locate vaccinia-infected tumor cells and destroy them. The two-front attack on tumor cells is what makes the modified vaccinia so effective.

"This is a very powerful and potent approach," said Dr. Antonio Chiocca, a professor at Ohio State University and a specialist in Oncological Neurosurgery. "You can think of each of these viruses as a new drug."

However, the side effects that come with these "viral drugs" may be much more dangerous than those of conventional drugs. The virus may become infectious to normal cells in rare cases, in which case extra medical effort must be placed to eliminate the vaccinia virus and the process becomes counter-productive. Also, any virus may have the ability to form a supervirus that is highly contagious and resistant to medical treatment, although Chiocca believes that this is unlikely for vaccinia since it can only survive in humans and most people have already been exposed to smallpox vaccines. However, the risk level increases dramatically if researchers begin using viruses that attack other species.

Nevertheless, current findings provide a much needed confidence boost in the area of viral therapeutic research. Viral usage in gene therapy and tumor reduction has been studied for over 10 years with unimpressive outcomes. But now things are looking bright for Thorne and company. "The results are very encouraging," said Thorne. "I would envisage clinical trials starting next year."




Written by Dennis Jiang

Reviewed and published by Pooja Ghatalia