Preliminary Data Add New Mechanistic Insights to Activity of Anthrax Anti-Toxin, Valortim(TM)
31 Juli 2007 - 12:00PM
PR Newswire (US)
ANNAPOLIS, Md. and PRINCETON, N.J., July 31 /PRNewswire-FirstCall/
-- PharmAthene, Inc., a biodefense company developing and
commercializing medical countermeasures against biological and
chemical threats, and Medarex, Inc. (NASDAQ:MEDX), a leading
monoclonal antibody company, today announced the results of new
studies showing that the companies' anthrax anti-toxin,
Valortim(TM) may possess the ability to enhance macrophage killing
of Bacillus anthracis (anthrax) spores within macrophages,
potentially blocking the ability of these spores to develop into
bacteria, thereby preventing toxin production and propagation of
the infection. The new data were recently presented by Dr. Alan
Cross, Professor of Medicine, University of Maryland School of
Medicine, Baltimore, Maryland, and Dr. Solomon Langermann, Vice
President and Chief Scientific Officer for PharmAthene, at the
Bacillus ACT 2007 International Conference on Bacillus anthracis
held June 17-21 in Oslo, Norway. Valortim, a fully human monoclonal
antibody generated by Medarex's UltiMAb(R) technology, is being
co-developed for potential use as an anti-toxin therapeutic to
prevent and treat inhalation anthrax. The studies presented by Drs.
Cross and Langermann explored the mechanism by which Valortim
promotes the killing of Bacillus anthracis (anthrax) in vitro (in
test tube). "These new data show that Valortim may enhance
macrophage killing of anthrax spores, and suggest that Valortim
might also be able to block germinating spores from producing
rapidly growing bacteria with release of the lethal toxins which
are usually fatal in infected individuals," said Dr. Cross.
"Another interpretation is that Valortim may neutralize the
deleterious effects of anthrax toxins in the immune system thereby
allowing the mouse innate immune system to deal more effectively
with the infection." A preclinical study led by Dr. Cross showed
that Valortim protected mice from lethal infection with Bacillus
anthracis. In the study, mice were pretreated with 5-10 mcg of
Valortim and then exposed to spores of the Bacillus anthracis
Sterne strain of anthrax via injection. Of the seven mice
pretreated with Valortim, all survived compared to seven mice in a
control group, in which none received Valortim and none survived.
These data extend the panel of animals in which the in vivo
protective activity of Valortim against anthrax infection has been
demonstrated, and offers an attractive mouse model for further
studies. In a second study, Valortim was applied in vitro to mouse
macrophages and Bacillus anthracis spores. The results showed that
the addition of Valortim enhanced the killing of Bacillus anthracis
(anthrax) spores by macrophages in a time and dose-dependent
manner. "We have assumed that the potent anthrax toxin neutralizing
activity of Valortim protects infected organisms from overwhelming
toxin production made by replicating bacteria," remarked Dr.
Langermann. "However, Dr. Cross' research suggests that activity of
Valortim may also be manifested at an earlier stage, by enhancing
the initial spore killing activity of macrophages, which are
specialized immune system cells. Further work is ongoing to more
fully characterize these intriguing results." "The presence of the
exosporium (a coating of bacterial derived components that normally
surround free spores) has been shown by Dr. Cross in previous
research to inhibit killing of spores by macrophages," commented
Dr. Israel Lowy, Senior Director of Clinical Science and Infectious
Diseases at Medarex. "The experiments suggest that Valortim might
negate inhibitory effects of the exosporium, and allow the
macrophage to regain its full sporicidal activity. We look forward
to further studies of this potential mechanism of Valortim in
impeding anthrax infection." The work reported by Dr. Cross is
supported by the Maryland Industrial Partnerships Program (MIPS).
The MIPS program was developed to accelerate the commercialization
of technology in Maryland by jointly funding collaborative R&D
projects between companies and University System of Maryland
faculty. About Valortim Valortim (MDX-1303) is a fully human
antibody designed to protect against anthrax infection, including
inhalation anthrax, the most lethal form of illness in humans
caused by the Bacillus anthracis bacterium. The investigational
antibody is designed to target a protein component known as the
anthrax protective antigen (PA) of the lethal toxin complex
produced by the bacterium. The anthrax protective antigen is
believed to initiate the onset of the illness by attaching to cells
in the infected person, and then is believed to facilitate the
entry of additional destructive toxins into the cells. Valortim is
designed to target anthrax protective antigen and protect the cells
from damage by the anthrax toxins. Valortim has been administered
intravenously and intramuscularly to healthy human volunteers in a
completed phase I study, and was well tolerated at doses as high as
20 mg/kg (IV), and was not immunogenic. These study results were
presented at the 2006 Annual Meeting of the Infectious Diseases
Society of America. Pharmacokinetic analysis suggested that doses
as low as 1 mg/kg resulted in circulating levels of antibody after
a month, with a similar potency for neutralizing anthrax toxin in
vitro as was seen with serum obtained from subjects who had been
vaccinated with anthrax vaccine. Preclinical studies suggest that
Valortim has the potential to provide protection against anthrax
infection when administered prophylactically (prior to the
emergence of symptoms of anthrax infection) and also may increase
survival when administered therapeutically (once symptoms become
evident). About Anthrax According to the Centers for Disease
Control and Prevention, anthrax is an acute infectious disease
caused by the spore-forming bacterium Bacillus anthracis. Anthrax
most commonly occurs in hoofed mammals and can also infect humans.
Symptoms of disease vary depending on how the disease is
contracted, but usually occur within seven days after exposure. The
serious forms of human anthrax are inhalation anthrax, cutaneous
anthrax, and intestinal anthrax. Initial symptoms of inhalation
anthrax infection may resemble a common cold. After several days,
the symptoms may progress to severe breathing problems and shock.
Inhalation anthrax is often fatal, even with the use of
antibiotics. Currently, antibiotics are the only drugs available
for therapeutic or prophylactic use, and post-exposure prophylaxis
is the only FDA-approved indication for such products. However,
antibiotic therapy, while useful, is associated with a number of
limitations, including: (1) lack of activity against the toxins
produced by the B. anthracis bacteria (2) need for long- term
dosing to achieve full protection complicated by side effects and
non- compliance (3) lack of efficacy when administered late in the
anthrax disease cycle, and (4) lack of effectiveness of current
antibiotics against multi-drug resistant or genetically engineered
strains of anthrax. About PharmAthene, Inc. PharmAthene, a
privately-held biotechnology company, was formed to meet the
critical needs of the United States by developing and
commercializing medical countermeasures against biological and
chemical weapons. PharmAthene's lead programs include Valortim(TM)
for the prevention and treatment of anthrax infection and
Protexia(R) for the prevention and treatment of morbidity and
mortality associated with exposure to chemical nerve agents. For
more information on PharmAthene, please visit
http://www.pharmathene.com/. In January 2007, PharmAthene announced
that it had signed a definitive merger agreement with Healthcare
Acquisition Corp. (AMEX:HAQ). HAQ has filed with the Securities and
Exchange Commission a definitive proxy statement in connection with
the proposed merger transaction involving PharmAthene. HAQ and its
directors and executive officers as well as PharmAthene and its
directors and executive officers may be deemed to be participants
in the solicitation of proxies for the special meeting of HAQ's
stockholders to be held to approve the proposed merger. Security
holders and other interested persons are urged to read the
definitive proxy statement regarding the proposed merger filed with
the securities and exchange commission on July 13, 2007 as it
contains important information about the proposed merger. HAQ's
definitive proxy statement has been mailed to HAQ's stockholders as
of a record date established for voting on the proposed merger.
Stockholders may also obtain a copy of the definitive proxy
statement, without charge, by directing a request to HAQ at: 2116
Financial Center, 666 Walnut Street, Des Moines, Iowa 50309. The
definitive proxy statement and the final prospectus and other SEC
filings of HAQ can also be obtained, without charge, at the
securities and exchange commission's internet site
(http://www.sec.gov/). HAQ and PharmAthene claim the protection of
the safe harbor for "forward- looking statements" within the
meaning of the private securities litigation reform act of 1995.
Forward-looking statements are statements that are not historical
facts. Such forward-looking statements, based upon the current
beliefs and expectations of management of HAQ and PharmAthene
regarding, among other things, the business of PharmAthene and the
merger, are subject to risks and uncertainties, which could cause
actual results to differ from the forward-looking statements. Risks
and uncertainties include risks associated with the reliability of
the results of the initial work conducted on Valortim(tm) relating
to animal efficacy, human safety and likelihood of successful
development of an efficient and scalable manufacturing process,
unexpected funding delays by NIAID, unforeseen safety issues
resulting from the handling of Bacillus anthracis, unforeseen
safety issues resulting from the administration of Valortim
(MDX-1303) in human subjects, uncertainties related to product
manufacturing. There can be no assurance that such development
efforts will succeed or that other developed products will receive
required regulatory clearance or that, even if such regulatory
clearance were received, such products would ultimately achieve
commercial success. About Medarex, Inc. Medarex is a
biopharmaceutical company focused on the discovery, development and
potential commercialization of fully human antibody-based
therapeutics to treat life-threatening and debilitating diseases,
including cancer, inflammation, autoimmune disorders and infectious
diseases. Medarex applies its UltiMAb(R) technology and product
development and clinical manufacturing experience to generate,
support and potentially commercialize a broad range of fully human
antibody product candidates for itself and its partners. More than
30 of these therapeutic product candidates derived from Medarex
technology are in human clinical testing or have had INDs submitted
for such trials, with seven of the most advanced product candidates
currently in Phase III clinical trials. Medarex is committed to
building value by developing a diverse pipeline of antibody
products to address the world's unmet healthcare needs. For more
information about Medarex, visit its website at
http://www.medarex.com/. Statement on Cautionary Factors For
Medarex: Except for the historical information presented herein,
matters discussed herein may constitute forward-looking statements
within the meaning of the Private Securities Litigation Reform Act
of 1995 that are subject to certain risks and uncertainties that
could cause actual results to differ materially from any future
results, performance or achievements expressed or implied by such
statements. Statements that are not historical facts, including
statements preceded by, followed by, or that include the words
"potential"; "believe"; "anticipate"; "intend"; "plan"; "expect";
"estimate"; "could"; "may"; or similar statements are
forward-looking statements. Medarex disclaims, however, any intent
or obligation to update these forward-looking statements. Risks and
uncertainties include risks associated with the reliability of the
results of the initial work conducted on Valortim(TM) (MDX-1303)
relating to animal efficacy, human safety and likelihood of
successful development of an efficient and scalable manufacturing
process, unexpected funding delays by NIAID, unforeseen safety
issues resulting from the handling of Bacillus anthracis,
unforeseen safety issues resulting from the administration of
Valortim in human subjects, uncertainties related to product
manufacturing as well as risks detailed from time to time in
Medarex's public disclosure filings with the U.S. Securities and
Exchange Commission (SEC), including its Annual Report on Form 10-K
for the fiscal year ended December 31, 2006 and its quarterly
reports on Form 10- Q. There can be no assurance that such
development efforts will succeed or that other developed products
will receive required regulatory clearance or that, even if such
regulatory clearance were received, such products would ultimately
achieve commercial success. Copies of Medarex's public disclosure
filings are available from its investor relations department.
Medarex(R), the Medarex logo and UltiMAb(R) are registered
trademarks of Medarex, Inc. All rights are reserved. Valortim(TM)
is a trademark of PharmAthene, Inc. All rights are reserved.
DATASOURCE: Medarex, Inc. CONTACT: Laura S. Choi, Investor
Relations, Ext. 2216, or Jean Mantuano, Corporate Communications
media, Ext. 2221, both of Medarex, Inc., +1-609-430- 2880; or
Stacey Jurchison, Director, Corporate Communications of
PharmAthene, Inc., +1-410-269-2610, Web site:
http://www.medarex.com/ http://www.pharmathene.com/ Company News
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