WATERTOWN, Mass., May 24 /PRNewswire-FirstCall/ -- V.I. Technologies, Inc.
(Nasdaq: VITX) ("Vitex" or "the Company"), a biotechnology company dedicated
to developing the next generation of anti-infective products, today announced
that Vitex scientists and their collaborators are presenting three reports
describing their progress in characterizing the viral target for the Company's
lead HIV drug, PA-457, at the Cold Spring Harbor Laboratory's 30th Annual
Meeting on Retroviruses, Cold Spring Harbor, NY, May 24-29, 2005. PA-457 is
the first in a new class of HIV drugs called Maturation Inhibitors, discovered
by Vitex scientists, with broad activity against HIV including strains
resistant to currently approved drugs. Drug resistance is the leading reason
for HIV treatment failure. PA-457 is a once a day oral drug that has been
shown to reduce plasma viral load following a single dose in HIV-infected
patients, including patients infected by HIV strains resistant to the three
major classes of existing HIV drugs. It is currently in Phase II clinical
trials.
Vitex scientists and collaborators previously demonstrated that PA-457
acts by a novel mechanism, whereby the compound blocks release of a key HIV
protein called capsid (CA) from its precursor (CA-SP1), thus preventing the
virus from undergoing normal maturation. Following PA-457 treatment, newly
formed HIV virus particles are non-infectious and virus replication is
terminated. At the Cold Spring Harbor Conference, three presentations will
describe the further elucidation of the interaction between PA-457 and its
viral target. The first study, to be presented by Dr. Michael Sakalian at the
University of Oklahoma Health Sciences Center, Oklahoma City, OK, is a
collaboration with Vitex scientists titled: "PA-457 INHIBITS MATURATION OF
THE HIV GAG PRECURSOR ASSEMBLED IN VITRO." This research demonstrated, for
the first time, that PA-457 blocks CA-SP1 cleavage in an in vitro cell-free
system. PA-457 activity in this system requires that the HIV core proteins
are assembled into an immature capsid-like structure. These results confirm
that PA-457 inhibits HIV replication by a unique mechanism, which explains the
compound's activity against viral strains resistant to existing classes of HIV
drugs. The study also provides a new experimental system for more detailed
analysis of the interaction between PA-457 and its target.
In a second report, Vitex scientist Dr. Feng Li will present data from a
collaborative study between Vitex and scientists from Dr. Eric Freed's
laboratory at the National Cancer Institute, Frederick, MD. In the study,
titled: "Determinants of Activity of the HIV Maturation Inhibitor PA-457 Map
to the GAG Protein CA-SP1 Domain," the researchers further defined the PA-457
target. They transferred amino acids from the HIV CA-SP1 junction into simian
immunodeficiency virus (SIV), a monkey virus that is related to HIV but is
resistant to PA-457. They then determined which residues are required to
render SIV sensitive to PA-457. Consistent with prior results related to the
mechanism of action of PA-457, it was demonstrated that the viral determinants
for PA-457 activity map to a string of CA residues adjacent to SP1, in
addition to the complete SP1 domain.
In the third paper, Dr. Catherine Adamson of Dr. Freed's laboratory will
present another collaborative study with Vitex, titled: "Viral resistance to
PA-457, a novel inhibitor of HIV maturation: Insights into the drug target and
mechanism of action." To elucidate further PA-457's target and mechanism of
action, PA-457-resistant viral variants were generated in vitro by serial HIV
passage at sub-optimum drug concentrations. Amino acid changes which
conferred PA-457-resistance were limited to the CA-SP1 cleavage site. No
resistance mutations were found elsewhere in the viral genome, confirming that
this site is the target for PA-457's antiviral activity. These results also
suggest that PA-457 should not induce cross-resistance to other classes of
compounds when used in HIV combination therapy.
Dr. Carl Wild, Vitex's Chief Science Officer who participated in all three
studies, commented, "These ongoing studies are allowing us to build a detailed
picture of the mechanism of action and molecular target of Maturation
Inhibitors. The results will allow Vitex to continue to play the leading role
in developing this potentially important new class of HIV drugs."
About PA-457
PA-457 is a small molecule, orally bioavailable HIV drug candidate.
Preclinical studies have shown that PA-457 retains full activity against drug-
resistant virus and is effective in an animal model of HIV infection. The
Company is currently enrolling a Phase IIa study of PA-457. The study, being
performed at leading institutions in the U.S., is designed to demonstrate the
antiviral potency of PA-457 following once-daily oral dosing for 10 days in
HIV-infected subjects who are not on other antiretroviral therapy. Results of
the Phase IIa clinical trial are expected in mid-2005. During the second half
of 2005, Vitex intends to initiate a Phase IIb study of PA-457 designed to
pave the way for pivotal Phase III studies.
The US Food and Drug Administration (FDA) has granted Fast Track
designation to PA-457. Fast Track is a process designed to expedite
development and approval of new drugs that may have the potential to improve
treatment for serious or life-threatening diseases. Developers of Fast
Tracked products have greater access to FDA resources as well as eligibility
for rolling NDA submissions. In addition, Fast Track designation may enable
priority FDA review and accelerated approval.
About Vitex
Vitex is developing the next generation of anti-infective products. The
Company is engaged in the discovery and development of small molecule oral
drugs for the treatment of HIV and other major human viral diseases. Vitex's
proprietary discovery technologies and lead therapeutic candidate PA-457 focus
on novel targets in the virus life cycle, including virus fusion and virus
maturation. The Company's separate INACTINE(TM) technology is designed to
inactivate a wide range of viruses, bacteria and parasites in blood products,
and has demonstrated its ability to remove prion proteins. The Company's
clinical development program for INACTINE(TM) has been suspended while the
Company continues to address issues relating to immune responses observed in
certain patients in Phase 3 clinical trials. For more information on Vitex,
please visit our web site at: http://www.vitechnologies.com.
Except for the historical information contained herein, the matters
discussed are forward-looking statements made pursuant to the safe harbor
provisions of the Private Securities Litigation Reform Act of 1995. These
statements involve risks and uncertainties, such as the progress of clinical
development of PA-457 and the timing of results of clinical trials, the
execution of the Company's financing plans, the timely availability of new
products, the Company's ability to execute plans to resume its clinical trial
program for the INACTINE(TM) viral inactivation system for red blood cells,
market acceptance of the Company's products, the impacts of competitive
products and pricing, government regulation of the Company's products, the
Company's ability to complete product development collaborations and other
strategic transactions and other risks and uncertainties set forth in the
Company's filings with the Securities and Exchange Commission. These risks
and uncertainties could cause actual results to differ materially from any
forward-looking statements made herein.
CONTACT:
John R. Barr
President
617-926-1551
john.barr@vitechnologies.com
SOURCE V.I. Technologies, Inc.
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Related links:
http://www.vitechnologies.com
CONTACT:
John R. Barr, President of Vitex,
+1-617-926-1551, john.barr@vitechnologies.com
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