New Approach to Treating Anthrax Significantly Improves Survival Rates in Pivotal Efficacy Studies

[Guest guest]

http://money.cnn.com/news/newsfeeds/articles/prnewswire/NETU03918122007-1.htm

- Human Genome Sciences' ABthrax shows lifesaving potential -- HGS on

track to deliver 20,000 doses to Strategic National Stockpile beginning in 2008

-

December 18, 2007: 07:00 AM EST

ROCKVILLE, Md., Dec. 18 /PRNewswire-FirstCall/ -- Human Genome Sciences,

Inc. today announced that the results of two animal studies demonstrated the

life-saving potential of its human monoclonal antibody drug ABthrax

(raxibacumab). The results show that a single dose of ABthrax, administered

without concomitant antibiotics, improved survival rates by up to 64 percent

when administered after animals were symptomatic for anthrax disease as a result

of inhalation exposure to massively lethal doses of anthrax spores. These

dramatic and statistically significant findings demonstrate a survival benefit

in two animal species, which is the requirement for establishing the efficacy of

new drugs used to counter bioterrorism.

(Logo: http://www.newscom.com/cgi-bin/prnh/20010612/HGSLOGO )

" We believe that ABthrax offers a significant step forward in the treatment of

inhalational anthrax, and could play an important role in strengthening

America's arsenal against bioterrorism, " said H. Watkins, President and

Chief Executive Officer, HGS.

ABthrax, which specifically targets anthrax toxins and is being developed

under contract with the Biomedical Advanced Research and Development Authority

(BARDA), represents a new way to address the anthrax threat. While antibiotics

can kill the Bacillis anthracis bacteria, they are not effective against the

deadly toxins that the bacteria produce -- the real culprits in anthrax- related

deaths. ABthrax targets anthrax toxins after they are released into the blood.

In an inhalation anthrax attack, people may not know they are infected with

anthrax until the toxins already are circulating in their blood, and it may be

too late for antibiotics alone to be effective.

" These results show that ABthrax was highly effective as a treatment for

anthrax in both rabbits and monkeys, and acted quickly to provide a significant

survival benefit to animals showing clinical symptoms caused by exposure to

massively lethal aerosolized doses of anthrax spores, " said C. Stump,

M.D., Executive Vice President, Research and Development, HGS. " The new data are

consistent with the results of previous studies in multiple animal models, which

demonstrated that a single dose of ABthrax given prophylactically provided up to

100% protection against death. "

HGS said that it has met all milestones to date under the Company's contract

with the U.S. Department of Health and Human Services (HHS), and is on track to

deliver ABthrax to the Strategic National Stockpile beginning in 2008.

" We have demonstrated the efficacy of ABthrax in multiple therapeutic and

prophylactic animal models of inhalational anthrax, " said H. , Ph.D.,

J.D., Executive Vice President and General Counsel, HGS. " We have demonstrated

that it was generally safe and well tolerated in two clinical trials to date in

healthy adults. We have manufactured conformance lots of ABthrax and are

currently producing ABthrax for delivery to the Stockpile. We have more work to

do, but our interactions with HHS, FDA and CDC continue to be positive, and the

ABthrax program is progressing well. "

Research Findings

In one of the animal studies, three groups of monkeys were exposed by

inhalation to anthrax spores and treated with either ABthrax or placebo after

they showed clinical signs of anthrax disease. After 28 days, the study found

that:

-- 64.3 percent of monkeys that received a single high dose of ABthrax

survived (p=0.0007 vs. placebo). -- 50 percent of those that received a low

dose survived (p=0.0064 vs. placebo). -- None of the monkeys in the

placebo control group survived.

A separate study that measured 14-day survival in rabbits also demonstrated a

statistically significant survival benefit versus placebo. All ABthrax-treated

animals that survived in both studies were rapidly cleared of anthrax toxin and

bacteria following intravenous administration of a single dose of ABthrax. In

contrast, all placebo-treated animals remained bacteremic or toxemic and died.

HGS also reported today that it has completed the second safety study of

ABthrax in human volunteers, bringing the total number of people who have

participated in human safety trials to more than 180. The clinical results to

date suggest that ABthrax was generally safe and well tolerated. In addition,

the new study demonstrated that co-administration of ABthrax with the antibiotic

Cipro (ciprofloxacin) did not affect the pharmacokinetics of either Cipro or

ABthrax, and suggested that ABthrax can be administered in combination with

antibiotics. This is a key finding given the important role that antibiotics are

expected to continue to play in the treatment of anthrax disease.

The Need for New Means to Fight Anthrax Infections

Two options are currently available for the prevention or treatment of anthrax

infections -- a vaccine and antibiotics. Both are essential to dealing with

anthrax, but both have limitations. The anthrax vaccine takes several weeks

following the initial doses before immunity is detectable, and requires multiple

injections over a period of eighteen months, in addition to annual booster

vaccination, to maintain protective immunity. Antibiotics are effective in

killing anthrax bacteria, but are not effective against the anthrax toxins once

those toxins have been released into the blood. Antibiotics also may not be

effective against antibiotic-resistant strains of anthrax.

ABthrax is a human monoclonal antibody to Bacillus anthracis protective

antigen that was discovered and developed by HGS, using technology that HGS has

integrated into the Company as part of its collaboration with Cambridge Antibody

Technology. ABthrax was the first investigational agent against anthrax

infection to be evaluated in a clinical study following the 2001 anthrax attacks

in the United States. In 2003, ABthrax received a Fast Track Product designation

from the FDA, as well as an Orphan Drug Designation for its use in the treatment

of inhalational anthrax disease.

In contrast to the anthrax vaccine, the protection afforded by a single dose

of ABthrax would be immediate following the rapid achievement of appropriate

blood levels of ABthrax. In contrast to antibiotics, ABthrax acts against the

deadly toxins produced by anthrax bacteria. It may also prevent and treat

infections by antibiotic-resistant strains of anthrax.

The ABthrax Contract with the U.S. Government

In June 2006, the U.S. Government exercised its option to purchase ABthrax for

the Strategic National Stockpile (Contract Number HHS010020050006C). HGS expects

to receive $165 million in revenues from this award, with the majority to come

in 2008, when the Company begins to deliver ABthrax. The purchase award was made

by the U.S. Department of Health and Human Services (HHS) under the Project

BioShield Act of 2004, which is designed to accelerate the development, purchase

and availability of medical countermeasures for the Strategic National

Stockpile.

Under the contract, HGS will manufacture and deliver 20,000 treatment courses

of ABthrax to the Strategic National Stockpile. The Company is also working

closely with HHS, FDA and CDC to complete the additional laboratory and clinical

testing required to support the filing of a Biologics License Application (BLA),

and to support the use of ABthrax in patients with inhalational anthrax disease

in the event of an emergency prior to FDA licensure.

About Anthrax

Anthrax infection is caused by a spore-forming bacterium, Bacillus anthracis,

which multiplies in the body and produces lethal toxins. Most anthrax fatalities

are caused by the irreversible effects of the anthrax toxins. Research has shown

that the bacteria produce protective antigen, the key facilitator in the

progression of anthrax infection at the cellular level. After protective antigen

and the anthrax toxins are produced by the bacteria, protective antigen binds to

the anthrax toxin receptor on cell surfaces and forms a protein-receptor complex

that makes it possible for the anthrax toxins to enter the cells. ABthrax blocks

the binding of protective antigen to cell surfaces and prevents the anthrax

toxins from entering and killing the cells.

About Human Genome Sciences

The mission of HGS is to apply great science and great medicine to bring

innovative drugs to patients with unmet medical needs.

The HGS clinical development pipeline includes novel drugs to treat hepatitis

C, lupus, anthrax disease, cancer and other immune-mediated diseases. The

Company's primary focus is rapid progress toward the commercialization of its

two key lead drugs, Albuferon® (albinterferon alfa- 2b) for hepatitis C and

LymphoStat-B® (belimumab) for lupus. Phase 3 clinical trials of both drugs are

ongoing. ABthrax (raxibacumab) is in late- stage development for the treatment

of anthrax disease. Other HGS drugs in clinical development include two TRAIL

receptor antibodies for the treatment of cancers.

For more information about HGS, please visit the Company's web site at

www.hgsi.com. For more information about ABthrax, please visit

www.hgsi.com/products/ABthrax.html. Health professionals or patients interested

in clinical trials or other studies involving HGS products may inquire via the

" Contact Us " section of the Company's web site,

www.hgsi.com/products/request.html, or by calling (301) 610-5790, extension

3550.

HGS, Human Genome Sciences, ABthrax, Albuferon and LymphoStat-B are trademarks

of Human Genome Sciences, Inc.

Safe Harbor Statement

This announcement contains forward-looking statements within the meaning of

Section 27A of the Securities Act of 1933, as amended, and Section 21E of the

Securities Exchange Act of 1934, as amended. The forward-looking statements are

based on Human Genome Sciences' current intent, belief and expectations. These

statements are not guarantees of future performance and are subject to certain

risks and uncertainties that are difficult to predict. Actual results may differ

materially from these forward-looking statements because of the Company's

unproven business model, its dependence on new technologies, the uncertainty and

timing of clinical trials, the Company's ability to develop and commercialize

products, its dependence on collaborators for services and revenue, its

substantial indebtedness and lease obligations, its changing requirements and

costs associated with facilities, intense competition, the uncertainty of patent

and intellectual property protection, the

Company's dependence on key management and key suppliers, the uncertainty of

regulation of products, the impact of future alliances or transactions and other

risks described in the Company's filings with the Securities and Exchange

Commission. In addition, the Company will continue to face risks related to

animal and human testing, to the manufacture of ABthrax and to FDA concurrence

that ABthrax meets the requirements of the ABthrax contract. If the Company is

unable to meet the product requirements associated with the ABthrax contract,

the U.S. government will not be required to reimburse the Company for the costs

incurred or to purchase any ABthrax doses. Existing and prospective investors

are cautioned not to place undue reliance on these forward-looking statements,

which speak only as of today's date. Human Genome Sciences undertakes no

obligation to update or revise the information contained in this announcement

whether as a result of new information, future events

or circumstances or otherwise.

Randi J. Airola, © 517-819-5926