UPDATE 2-US panel: More study on Human Genome anthrax drug

* FDA panel: Animal studies predict human effects
* More study needed to show benefit over antibiotics -panel
* Shares fall 1.1 percent
(Recasts first sentence, adds comments by company and
analyst)

By Lisa Richwine

SILVER SPRING, Md., Oct 27 (Reuters) - Animal data suggests
a proposed Human Genome Sciences Inc (HGSI.O) drug may help
people exposed to anthrax but more study is needed to show the
treatment adds benefit beyond antibiotics alone, a U.S.
advisory panel said on Tuesday.

The Food and Drug Administration did not ask the panel for
a recommendation on whether it should approve the company's bid
for approval for treating anthrax infection. The FDA said
recent inspections raised questions about tests used to measure
the drug's absorption in people, making it impossible to judge
if the product was fit for approval.

Anthrax is a bacterium that can cause a potentially fatal
lung infection if inhaled. Letters carrying powdered anthrax
killed five people in 2001, and experts fear it could be used
again in a biological attack.

The U.S. government already has ordered 65,000 doses of
Human Genome's drug, known as ABthrax or raxibacumab, for a
national stockpile of emergency medicines ahead of the FDA
review.

Officials with Human Genome Sciences said they felt they
could address the FDA's concerns and hoped the agency would
clear ABthrax with a commitment for further studies after
approval.

Human Genome's application relies largely on studies in
rabbits and monkeys. FDA rules allow animal tests in lieu of
human studies to show the effectiveness of new drugs to fight
certain deadly infections where testing in humans would be
unethical.

The panel voted 16-7, with one abstention, that evidence
from the animal studies predicted the response in humans. In
those tests, a single intravenous dose of ABthrax worked better
than a placebo but similar to antibiotics for treating anthrax
infection, FDA reviewers said.

"It is clearly protective in these animal models, and I
think there is every reason to expect it would be beneficial in
humans," said panel member Stephen Leppla, acting chief of the
bacterial diseases laboratory at the National Institute of
Allergy and Infections Diseases.

The majority, however, voted that the FDA should request
evidence from animal studies to show that adding ABthrax to
antibiotics worked better than antibiotics alone. The question
did not specify if the agency should seek that data before or
after the drug's approval.

"We definitely want to be sure it has some benefit in
addition to the antibiotics," said Dr. Archana Chatterjee, a
panel member and chief of the pediatrics infectious diseases
division at Creighton University School of Medicine in
Nebraska.

The FDA said it will consider if new animal or human
studies are needed once an investigation of the testing issues
is complete and it weighs the panel's advice.

The panel narrowly voted that evidence showed the medicine
would not reduce the effectiveness of antibiotics.

Human Genome said new options to fight anthrax were needed
because antibiotics do not always work, and the U.S. government
has called for alternatives to protect the public.

"Current established therapies are not sufficient," Sally
Bolmer, a senior vice president at Human Genome, told the
panel.

ABthrax takes a new approach to fighting anthrax by
targeting the toxin made by the bacteria rather than the
microbe itself. It is designed to attack and neutralize the
toxin that makes anthrax so deadly.

Dr. David Stump, a Human Genome executive vice president,
said after the meeting the company was pleased the panel backed
the animal studies to show effectiveness.

He also said the company was confident in the tests that
raised FDA concerns and was working to answer the questions
before the mid-November deadline for an approval decision.

Those types of issues are "not unusual. Unfortunately it
came up so late it couldn't get resolved" before the panel
meeting, he said.

Stump added that he hoped the company could win FDA
clearance with a commitment to run further studies after
approval.

Human Genome said in July the company would record more
than $160 million through the first two quarters of 2009 from
government sales of the drug. It is due to receive $10 million
more if ABthrax wins FDA approval.

Human Genome's shares fell 1.1 percent to close at $19.21
on the Nasdaq. The stock has soared nearly 500 percent since
July after unexpectedly positive results for an experimental
lupus drug that analysts see as a potential blockbuster.
(Reporting by Lisa Richwine; Editing Bernard Orr and Matthew
Lewis)