New drug fights back against deadly ricin toxin

Members of a Hazmat team prepare to enter the Russell Senate Office Building on Capitol Hill, February 4, 2004 in Washington, DC. Three Senate office buildings are closed after a letter found in the Senate Majority leader Bill Frist (R-TN) office was cofirmed to contain the poison Ricin. (Credit: Mark Wilson/Getty Images)

A new study shows for the first time that an experimental drug can save nonhuman primates exposed to ricin, a potential bioterrorism agent.

“Clinically, there is no treatment that can be administered currently to save someone in the event of an exposure to this toxin,” says Chad Roy, director of biodefense research programs at Tulane University’s National Primate Research Center, and lead author of the paper, which appears in JCI Insight.

“Our study shows proof of concept in a near-clinical animal model, the nonhuman primate, that we finally have a life-saving treatment against one of the world’s most notorious toxin agents.”

Ricin, a highly lethal toxin, derives from castor oil plant seeds. A dose of purified ricin powder the size of a few grains of table salt can kill an adult. Due to its toxicity and the ubiquity of source material, experts consider it a leading bioterrorism threat.

Researchers used a drug comprised of humanized monoclonal antibodies against the toxin. They developed the drug from research of a successful ricin vaccine and engineered the therapeutic to look very similar to the structure of antibodies that vaccinated nonhuman primates generated.

The findings show the drug is much more effective four hours after exposure as opposed to 12 hours after exposure, indicating a short time window for successful treatment. Researchers plan to develop a stronger version to “expand the therapeutic window” for effective treatment longer after exposure, Roy says.

Researchers also hope to develop the drug as a possible prophylactic therapeutic that emergency workers or members of the military could take before they enter areas contaminated with ricin.

The research is part of federal efforts to develop a stockpile of effective countermeasures against bioterrorism agents.

Additional researchers from Tulane, Mapp Biopharmaceutical Inc., the University of Texas Southwestern Medical Center, and the New York State Department of Health contributed to the work.

Source: Tulane University