With the severe acute respiratory syndrome (SARS) epidemic spreading, it's easy to overlook an equally serious threat: bioterrorism. The situation in Iraq and heightened tension throughout the Middle East may raise the likelihood of a chemical or biological attack against U.S. targets. The Homeland Security Dept. has repeatedly warned that terrorist groups could be planning such assaults (see BW Online, 4/28/03, "'Security Becomes Embedded'"). And as the still-unsolved anthrax attacks of 2001 showed, America's arsenal of vaccines and drugs is far from adequate.
Thanks to a little-noted gesture by the Food & Drug Administration last summer, though, dozens of biotech companies are stepping in to fill the void. Under a regulation dubbed the "animal rule," the FDA is permitting drugmakers to rely more heavily on animal experiments for chemical or bioterrorism remedies in cases -- anthrax, for example -- where human tests are infeasible or unethical.
The rule won't make the approval process a cakewalk, but it will clear some roadblocks. "The crux of the issue was: How do you develop a drug when you don't have any people with the disease?" notes Dr. Dianne Murphy, director of the FDA's Office of Counterterrorism & Pediatric Drug Development.
The animal rule is already reaping dividends. In February, the FDA approved a chemical called pyridostigmine bromide to treat soldiers exposed to the nerve gas Soman, after the U.S. Army tested the compound in guinea pigs and monkeys. Says Army Colonel John Grabenstein, deputy director for clinical operations at the Military Vaccine Agency: "It's important to explore new advances to see how they might be applied to our existing capabilities."
One company trying to lead the bioterrorism charge is San Diego's Vical (VICL ), which developed a vaccine by creating a chemical copy of anthrax DNA and then altering it. The concoction stimulates immune cells to make antibodies against anthrax but won't transmit the disease. In one test, 40 rabbits that were given the vaccine and then exposed to anthrax survived, while 17 that were left unprotected died. Vical is now working with the FDA to design a second animal study.
The need for new anthrax remedies can't be overstated. While the government is unlikely to recommend mass vaccinations, the military is desperate for an alternative to the current vaccine, which requires six injections over 18 months, plus annual boosters. Vical and other biotechs hope to produce drugs that stay potent longer. The goal is not only to make better vaccines but also to develop more targeted drugs to treat unvaccinated victims. Cipro and other drugs work against anthrax only when administered soon after exposure.
KEEPING IN TOUCH.
Human Genome Sciences (HGSI ) in Rockville, Md., is developing an antibody-based drug so potent that a single dose might be able to prevent anthrax and treat it as well. Rather than targeting the anthrax bacteria, as antibiotics do, HGSI's drug, called ABthrax, attacks the toxins emitted by the bugs, preventing them from entering and killing cells.
In addition, says HGSI CEO William Haseltine: "It may prevent and treat infections by antibiotic-resistant strains." On Mar. 18, the company announced that ABthrax is 100% effective in rabbits and more than 90% effective in nonhuman primates.
The trick will be getting these treatments over the remaining regulatory hurdles. Each company will have to work closely with the FDA to determine which animals are used in further trials. And they'll still have to run human trials to show that their products are safe. "It isn't a shortcut," says Dr. Una Ryan, CEO of Avant Immunotherapeutics (AVAN ), which is working on vaccines for anthrax and plague. "We have to feel our way through this process."
The federal government has proposed setting aside $6 billion to fund counterterrorism initiatives over the next 10 years, such as improving animal research facilities. And the FDA promises to consult early and often with drug companies. "We want them to come in and talk to us when the drug is barely a glimmer in a scientist's eye," says the FDA's Murphy. The agency is counting on those glimmers -- and so is the rest of the country.
By Arlene Weintraub in Los Angeles
Edited by Douglas Harbrecht