Antibody Prevents Death in Animals Exposed to Anthrax and Shows Unexpected Protective Benefits

PINE BROOK, N.J. -- Scientists from Elusys

Therapeutics, Inc. presented data today showing that the company's anthrax

antibody, ETI-204, provides complete protection from death due to anthrax

exposure in two animal species, and may clear anthrax bacteria from the site

of infection and from the bloodstream. The data were presented at the

American Society for Microbiology's Biodefense Research Meeting in Baltimore.

ETI-204, an affinity-enhanced monoclonal antibody (Mab), is being

developed as a drug for prevention and treatment of infection and death caused

by anthrax toxin.

"ETI-204 continues to deliver strong data demonstrating its protective

power at low doses," said Linda Nardone, PhD, vice president of clinical and

regulatory affairs for Elusys and director of the company's anthrax biodefense

program. "ETI-204 is one of the best anti-anthrax antibodies under

development."

Leslie Casey, PhD, senior director of research at Elusys, presented the

results of two key studies at the meeting. One trial showed that mice given

ETI-204 fared significantly better than those given a non-affinity enhanced

Mab (14B7) or placebo. The mice received ETI-204, 14B7 or placebo followed by

injection of anthrax spores into the trachea. All of the mice given ETI-204

were still alive at the end of the 14-day trial. Even more significantly,

none of the mice given ETI-204 had evidence of anthrax bacteria spreading to

the spleen.

The second study found that the Elusys Mab completely protected rabbits

exposed to aerosolized anthrax. ETI-204 was given intravenously to the

animals in the study group immediately before exposure to a lethal dose of

aerosolized anthrax. The control group received no drug. All of the animals

given ETI-204 survived the 28-day study, whereas none of the rabbits in the

control group survived past five days.

Casey presented compelling new data based on blood samples drawn from

the rabbits to determine the level of anthrax bacteria in the blood and major

organs. These data go beyond the survival data for the rabbits that were

previously released.

Seven of the nine rabbits treated with ETI-204 had no evidence of bacteria

in the lungs, which was the site of infection, and none of the treated rabbits

had bacteria in their blood at any time point. This was unexpected because

ETI-204 targets the anthrax toxin, not the bacteria, yet it seems to clear

bacteria from the site of infection and to keep it out of circulation in the

bloodstream.

Also remarkable was that there was no evidence of ETI-204 in the

bloodstreams of the treated rabbits by day 28, yet the rabbits remained free

of infection.

"Our pre-exposure studies show that a single low dose of ETI-204 before

exposure to lethal levels of anthrax protects the animals from death caused by

anthrax toxin, but does even more than that," commented Casey. "It was

unexpected, but striking, that our Mab prevented bacteria from entering the

bloodstream and cleared the bacteria from the site of infection. ETI-204

appears to have some very beneficial effects that we plan to study further."

Finally, blood samples from the rabbits indicated that the animals

developed their own antibodies to the anthrax toxin. "ETI-204 may also enable

recipients to mount their own immune response to anthrax. We may test this

further to verify the effectiveness and duration of this effect," added Casey.

"We have new data showing that ETI-204 protects animals when it is given

after they have been exposed to anthrax spores," added Nardone. "In

addition, we have excellent data that show protective levels of ETI-204 can be

deliver by intramuscular injection, which will allow more rapid deployment

than intravenous injection, especially in emergency situations." Elusys will

release the post-exposure and intramuscular data in the near future.

ETI-204 is an affinity-enhanced, de-immunized antibody, which means that

its ability to bind to its target pathogen has been strengthened and that

elements that might cause an immune response have been removed. ETI-204

targets and binds to Protective Antigen, which prevents the anthrax toxins

from binding to and entering the cells in the body, thereby preventing death.

Elusys develops antibody-based therapies using proprietary technology in

Heteropolymer antibody chemistry and complement biology. The company's

pipeline of products includes treatments for cancer, lupus nephritis,

infectious diseases and thrombosis. The company has successfully advanced

three products to the IND and Phase I stage, with additional products in its

pipeline.

Source: Elusys