New drug blocks anthrax toxin in animals

A synthetic protein called ToxBlox protects animals from anthrax infection and death, according to data reported Sunday in Washington, DC, at a meeting of the American Society for Microbiology.

ToxBlox is an inhibitor of anthrax toxin action, Dr. Solomon Langermann from PharmAthene Inc., in Annapolis, Maryland, noted in an interview with AMN Health.

"Once anthrax spores are taken up into the lungs, they get into certain cells where they germinate and enter the blood stream where they make a very potent toxin," Langermann explained.

"ToxBlox is a novel therapeutic designed to block the ability of the anthrax toxin to get into cells where it has lethal effects. A lot of therapies work too late in the process when those exposed are already symptomatic and the toxic effects are pretty far along," he added.

In an earlier proof-of-concept study, ToxBlox protected rats from death when injected up to 4 hours after exposure to a normally lethal dose of anthrax. In the latest studies, New Zealand White rabbits were injected with a high dose of anthrax, and then treated 30 minutes later with ToxBlox or an inert compound.

Five of 6 rabbits treated with high-dose ToxBlox survived free of symptomatic anthrax infection for a period of 90 days. In contrast, the average time to death in control animals was 2.5 days, and 4 days for animals treated with low-dose ToxBlox.

"We are very pleased with the results so far," Langermann told Reuters Health. "We basically demonstrated in an appropriate animal model for anthrax challenge that the molecule works."

He added, "We've done a second animal study now, which mimics aerosol delivery and uptake into the lungs and we are planning on starting human trials in the next month."