Oncolytic Salmonella: Dirty Poultry for Cancer Therapy?

Loeffler et al. report on the anti-tumor activity of an attenuated Salmonella bacterial strain engineered to express the mammalian immunostimulatory gene LIGHT, online this month in PNAS. How about a clinical trial on chickens with tumors? Or will Kentucky Fried Chicken give the Salmonella to their birds and market a new 6-piece anti-cancer meal? "Will that be a white or brown therapy today?". Just kidding. Oncolytic bacterial therapy for cancer is of course a very legitimate and promising area of therapeutic research. Clinical trials and manufacture of biological therapeutics are highly regulated and controlled to ensure human safety. Sorry KFC.

Pharming Interferon in Tobacco Plants

Those of us who work with VSV know interferon as a secreted protein that can protect cells from viral infection. The interferon response is also the basis for selective tumor cell killing by many experimental oncolytic viruses.

However interferon is also biotherapeutic of significance in its own right - it is the world's third most produced biological, second only to insulin and erythropoietin. Interferon-alpha is currently administered as first-line treatment in Hepatitis C and is also approved for Hepatitis B and some types of cancer. Another variant of interferon (beta) is approved for use in multiple sclerosis patients.

But biologicals ain't cheap. A years worth of IFN treatment for HepC costs $26, 000 USD, placing a huge burden on health care systems and making it inaccessible to the majority of infected individuals worldwide, who lack the privilege of luxurious health care. One of the major reasons for the high cost of biologicals such as IFN lies in production. Currently, IFN is produced in cultured cell lines, which require stringent growth conditions and laborious sterile handling procedures. In an effort to lower production costs, this new paper describes the production of human interferon in the chloroplasts of tobacco plants. Thus the protein is produced through standard agriculture, leaves are harvested (each makes 3mgs of IFN) and the protein is purified through a relatively straightforward and scalable process. I couldn't find a patent for this technology on Google patents, and Henry Daniell's lab, which conducted this research, seems to have a specific policy of developing biotechnology that is globally accessible. Hopefully plants like these will lead pave the way to cheap, disseminated biological production capacities to meet local demand across the world.