A new Stanford study published in Cell Host and Microbe has
demonstrated that VXA-A1.1, an investigational oral tablet flu
vaccine under development by Vaxart, Inc. (NASDAQ: VXRT), had
cellular correlates of protection against influenza infection.1
These cellular correlates were found using mass
cytometry analysis of vaccine-elicited cellular immune responses in
the peripheral blood of participants in a previously reported Phase
II H1N1 challenge study of VXA-A1.1.2
The U.S. Centers for Disease Control and
Prevention (CDC) estimates that, on average, 36,000 people in the
U.S. died from the flu in each of the past ten years. It is
estimated that 61,000 people in the U.S. died from the flu in the
2017-2018 season – the highest toll in recent years. The 2019-2020
season, which was shorter than normal, resulted in approximately
22,000 U.S. deaths.3 Globally, the number of annual flu deaths has
been estimated to range from nearly 300,000 to more than
600,000.4
“The data show that cellular responses are
potentially more relevant for protection for an oral vaccine than
circulating antibody responses,” said David McIlwain, Ph.D., senior
research scientist in the Department of Microbiology and Immunology
at the Stanford School of Medicine and lead author of the
study.
“These results support using early immune
response data to predict protection against respiratory pathogens
several months later, potentially speeding vaccine development,”
said Sean Tucker, Ph.D., Vaxart’s founder and chief scientific
officer and a co-author of the publication.
About the Study
Results of a Phase II human influenza challenge study following
vaccination with VXA-A1.1, which was funded by the U.S.
government’s Biomedical Advanced Research and Development Authority
(BARDA), have previously been reported.2 Participants in the Phase
II study received either VXA-A1.1, an injected quadrivalent,
inactivated influenza vaccine (IIV) or a placebo. Participants were
challenged with H1N1 influenza virus 90-120 days after vaccination
and were monitored for signs and symptoms of infection and viral
shedding.
Results of the Phase II study were the first to show that
VXA-A1.1 offered greater protection against viral shedding than the
injected IIV. The results suggested that cellular responses rather
than neutralizing antibodies may be especially important in the
VXA-A1.1 mechanism of protection.2
The study announced today is the first to use mass cytometry to
evaluate more than 40 different immune cell parameters in
peripheral blood samples collected from 141 participants in the
Phase II study. Mass cytometry immune cell profiling was performed
on samples collected immediately prior to (day 1) and seven days
following (day 8) vaccine administration.
Immune profiling tracked levels of multiple cell subsets with
similar patterns of markers. The relationship between each subset
and virus shedding was determined. Random forest-based machine
learning models were used to define high-dimensional cellular
correlates between the immune profiling and viral shedding
data.
Key Findings
Key findings from the study include:
- Specific B cell and T cell responses
contribute to protection from viral shedding with VXA-A1.1 but not
with IIV.
- At day 8, vaccine-elicited subsets
of plasmablasts (including α4β7+, CD62L-, pSTAT5+ cells) and
hemagglutinin (HA+)-specific cells significantly correlated with
protection from viral shedding after day 90 in participants
vaccinated with VXA-A1.1, but not in participants treated with IIV
or placebo.
- At day 8, VXA-A1.1, but not IIV or
placebo, elicited subsets of T cells expressing markers (β7
integrin and CCR9) that are indicative of enhanced homing to
mucosal tissue.
- Random forest models of the
VXA-A1.1-treated group could distinguish those individuals who were
later protected versus those who remained susceptible to the virus
using datasets from both unsupervised clustering approaches and
manual gating (p= 0.00001).
References
1 McIlwain D, Chen H, Rahil Z, et al. Human influenza virus
challenge identifies cellular correlates of protection for oral
vaccination. Cell Host Microbe (2021).
doi:10.1016/j.chom.2021.10.009
2 Liebowitz D, Gottlieb K, Kolhatkar NS et al. Efficacy,
immunogenicity, and safety of an oral influenza vaccine: a
placebo-controlled and active-controlled phase 2 human challenge
study. Lancet Infect Dis. 2020;20:435-444.
3 USA Facts. How many people die from the flu? Available at:
https://usafacts.org/articles/how-many-people-die-flu/
4 Paget J, Spreeuwenberg P, Charu V et al. Global mortality
associated with seasonal influenza epidemics: New burden estimates
and predictors from the GLaMOR Project. J Glob Health.
2019;9(2):020421.
About Vaxart Vaxart is a
clinical-stage biotechnology company developing a range of oral
recombinant vaccines based on its proprietary delivery platform.
Vaxart vaccines are designed to be administered using tablets that
can be stored and shipped without refrigeration and eliminate the
risk of needle-stick injury. Vaxart believes that its proprietary
tablet vaccine delivery platform is suitable to deliver recombinant
vaccines, positioning the company to develop oral versions of
currently marketed vaccines and to design recombinant vaccines for
new indications. Vaxart’s development programs currently include
tablet vaccines designed to protect against coronavirus, norovirus,
seasonal influenza, and respiratory syncytial virus (RSV), as well
as a therapeutic vaccine for human papillomavirus (HPV), Vaxart’s
first immune-oncology indication. Vaxart has filed broad domestic
and international patent applications covering its proprietary
technology and creations for oral vaccination using adenovirus and
TLR3 agonists.
Note Regarding Forward-Looking
Statements This press release contains forward-looking
statements that involve substantial risks and uncertainties. All
statements, other than statements of historical facts, included in
this press release regarding Vaxart's strategy, prospects, plans
and objectives, results from pre-clinical and clinical trials,
commercialization agreements and licenses, and beliefs and
expectations of management are forward-looking statements. These
forward-looking statements may be accompanied by such words as
"should," "believe," "could," "potential," "will," "expected,"
"plan," and other words and terms of similar meaning. Examples of
such statements include, but are not limited to, statements
relating to Vaxart's ability to develop and commercialize its
product candidates, including its vaccine booster products;
Vaxart's expectations regarding clinical results and trial data;
and Vaxart's expectations with respect to the effectiveness of its
product candidates. Vaxart may not actually achieve the plans,
carry out the intentions, or meet the expectations or projections
disclosed in the forward-looking statements, and you should not
place undue reliance on these forward-looking statements. Actual
results or events could differ materially from the plans,
intentions, expectations, and projections disclosed in the
forward-looking statements. Various important factors could cause
actual results or events to differ materially from the
forward-looking statements that Vaxart makes, including
uncertainties inherent in research and development, including the
ability to meet anticipated clinical endpoints, commencement,
and/or completion dates for clinical trials, regulatory submission
dates, regulatory approval dates, and/or launch dates, as well as
the possibility of unfavorable new clinical data and further
analyses of existing clinical data; the risk that clinical trial
data are subject to differing interpretations and assessments by
regulatory authorities; whether regulatory authorities will be
satisfied with the design of and results from the clinical studies;
decisions by regulatory authorities impacting labeling,
manufacturing processes, and safety that could affect the
availability or commercial potential of any product candidate,
including the possibility that Vaxart's product candidates may not
be approved by the FDA or non-U.S. regulatory authorities; that,
even if approved by the FDA or non-U.S. regulatory authorities,
Vaxart's product candidates may not achieve broad market
acceptance; that a Vaxart collaborator may not attain development
and commercial milestones; that Vaxart or its partners may
experience manufacturing issues and delays due to events within, or
outside of, Vaxart's or its partners' control; difficulties in
production, particularly in scaling up initial production,
including difficulties with production costs and yields, quality
control, including stability of the product candidate and quality
assurance testing, shortages of qualified personnel or key raw
materials, and compliance with strictly enforced federal, state,
and foreign regulations; that Vaxart may not be able to obtain,
maintain, and enforce necessary patent and other intellectual
property protection; that Vaxart's capital resources may be
inadequate; Vaxart's ability to resolve pending legal matters;
Vaxart's ability to obtain sufficient capital to fund its
operations on terms acceptable to Vaxart, if at all; the impact of
government healthcare proposals and policies; competitive factors;
and other risks described in the "Risk Factors" sections of
Vaxart's Quarterly and Annual Reports filed with the SEC. Vaxart
does not assume any obligation to update any forward-looking
statements, except as required by
law. Contacts
Vaxart Media Relations: |
Investor Relations: |
Mark Herr |
Andrew Blazier |
Vaxart, Inc. |
FINN Partners |
mherr@vaxart.com |
IR@vaxart.com |
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(203) 517-8957 |
(646)
871-8486 |
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