A modified anthrax toxin may be an effective cancer therapy,
as indicated by studies led by investigators at the National Institutes of Health (Liu S et al. J Biol Chem. 2008;283:529-540).
To give anthrax toxin high tumor specificity, the team developed anthrax toxin variants that require activation by matrix metalloproteinases,
proteins that are overproduced in cancer cells.
When the investigators tested a mutated toxin in mice, 100%
of the animals tolerated a dose that would otherwise have been lethal.
The modified toxin was better at killing melanoma tumors than the natural toxin due to its higher specificity and longer half-life in the blood. The modified toxin also could kill other types of cancer cells, such as those from colon and lung tumors. The investigators found that this anticancer activity largely reflected the indirect targeting of tumor vasculature and angiogenic processes.
Hampton T. Anthrax and Cancer. JAMA. 2008;299(5):513. doi:10.1001/jama.299.5.513-b