PaxVax Inc, which develops and commercializes innovative vaccines
against infectious diseases in a socially responsible manner, today
announced interim data from a Phase 3 cholera challenge study of its
single-dose oral cholera vaccine candidate, PXVX0200 (also known as CVD
103-HgR). Trial investigators compared the rate of diarrhea in
participants vaccinated with PXVX0200 to the rate in participants who
had received placebo. The vaccine appeared well tolerated. In an interim
analysis of participants challenged at 10 days post vaccination with
wild type, fully pathogenic cholera bacteria the rate of diarrhea was
reduced in the vaccine group: 20 of 33 participants who received placebo
experienced moderate-to-severe diarrhea compared to two of 35
participants who received PXVX0200.
Vaccine efficacy is evaluated when volunteer participants are immunized
with an oral dose of the PXVX0200 vaccine or placebo and are then
subsequently exposed to the cholera-causing agent (Vibrio cholerae
O1 El Tor). Volunteer participants in this challenge study were divided
into two groups - the first group was vaccinated and then challenged at
10 days after vaccination. As part of the study design, a second,
separate group of volunteer participants will be challenged at 90 days
post vaccination to further evaluate duration of vaccine protection.
Final study results will be reported as a "co-primary endpoint", which
will combine both challenge time points at 10 and 90 days after
Cholera is an acute intestinal diarrheal infection caused by toxigenic Vibrio
cholerae bacteria generally acquired by ingesting contaminated water
or food. According to the World Health Organization, the global disease
burden is estimated to be three to five million cases and 100,000 to
130,000 deaths per year. Cholera often manifests as explosive epidemics
that rapidly move through populations, such as the outbreaks that
occurred in Peru and Haiti in 1991 and 2010, respectively.
This pivotal efficacy cholera challenge study is a randomized,
double-blind, placebo-controlled trial nderway at three top vaccine
testing centers: the Center for Vaccine Development of the University of
Maryland School of Medicine, the University of Vermont Vaccine Testing
Center, and Cincinnati Children's Hospital Medical Center.
Wilbur Chen, M.D., M.S., Assistant Professor at the University of
Maryland School of Medicine, Center for Vaccine Development and Primary
Investigator commented on the study: "Interim results are highly
encouraging and justify continuing the study to evaluate protection from
cholera challenge 90 days post vaccination, as well as proceeding with
the additional planned studies of safety, immunogenicity, and lot-to-lot
consistency of this cholera vaccine".
A vaccine for cholera is not currently available for U.S. residents who
travel abroad to areas where cholera poses a risk (e.g., Haiti). A
cholera vaccine is available in Europe and elsewhere for travelers, but
it requires a two-dose regimen. If licensed, the single-dose, oral
PXVX0200 vaccine would be more convenient for all travelers,
particularly for those traveling on short notice.
In addition to the 10-day and 90-day cholera challenge studies,
immunogenicity, safety, and lot consistency of the PXVX0200 cholera
vaccine will be evaluated in a broader population at trial sites in
Canada, Australia, and the U.S. Approximately 3,000 participants will be
enrolled in these additional pivotal Phase 3 clinical studies.
"As a result of favorable data reported from the 10-day challenge
component we will continue with the Phase 3 program, and look forward to
additional positive results that will provide the evidence-base to
support a Biologics License Application for PXVX0200, our lead vaccine
candidate," said Ken Kelley, Chief Executive Officer of PaxVax. "We are
excited about the prevailing opportunity to protect U.S. travelers from
cholera, and also believe that PXVX0200 may allow us to bring a
logistically simple, single-dose cholera vaccine to developing countries
for use during explosive cholera outbreaks."
Positive results from the previous Phase 1 trial showed that a single
oral dose of PXVX0200 was highly immunogenic; overall, seroconversion of
vibriocidal antibody occurred in 89 percent of vaccinees by day 14.
Onset of immune response induced by the vaccine was also rapid with 80
percent of subjects demonstrating seroconversion by 10 days after
administration. The vaccine was well tolerated; adverse events were
infrequent and generally mild and comparable to placebo. PXVX0200 is the
same attenuated vaccine strain (CVD 103-HgR) that was previously
approved and marketed in several countries under the brand names
"Orochol" and "Mutacol."
PaxVax is a privately held company established in 2007 to develop and
commercialize innovative vaccines against infectious diseases. PaxVax
has a clinical-stage product portfolio including a cholera vaccine that
recently initiated Phase 3 clinical trials, a pandemic H5N1 influenza
vaccine entering Phase 2 clinical trials, two anthrax vaccines in Phase
1 clinical trials under contract with the National Institutes of Health
(NIH), and an HIV vaccine in Phase 1 clinical trials also under contract
with the NIH. The company's proprietary adenoviral-based technology
platform enables the rapid development of oral vaccines that can target
any viral or bacterial protein antigen. PaxVax's vaccine candidates are
designed to be easier to manufacture, store, distribute, administer, and
deliver across the globe than conventional injectable vaccines while
enhancing the desired immune response to the vaccine antigens. PaxVax is
headquartered in Menlo Park, Calif. with Research & Development
laboratories and a licensed Good Manufacturing Practice (GMP) production
facility in San Diego, Calif.
More information about PaxVax is available at www.PaxVax.com.
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