Altimmune Demonstrates Strong Neutralization of South African Variant in Preclinical Study of Intranasal AdCOVID™
May 26 2021 - 7:00AM
Altimmune, Inc. (Nasdaq: ALT), a clinical-stage biopharmaceutical
company, today announced new results from a preclinical study
demonstrating the ability of its AdCOVID vaccine candidate to
neutralize the rapidly emerging SARS-CoV-2 B.1.351 variant of
concern that originated in South Africa. B.1.351 carries multiple
mutations in the receptor binding domain (RBD) including the E484K
mutation that has been shown to substantially decrease the ability
of authorized vaccines to neutralize the virus.
In the current study, performed in collaboration
with investigators at Saint Louis University, the neutralizing
titer against the B.1.351 variant virus was only 4.4-fold lower
than the neutralizing titer against an original or ancestral
Wuhan-like isolate when measured seven weeks after a single
intranasal dose of AdCOVID. Furthermore, in mice that received a
booster dose of AdCOVID, the reduction in the neutralizing titer
against the B.1.351 variant was only 1.8-fold lower at seven weeks
post vaccination; statistically the same as the neutralization
titer against the Wuhan isolate. The serum neutralizing antibody
titers were determined using a live virus focus reduction
neutralization titer (FRNT) assay with a 50% neutralization
endpoint.
“These data are impressive considering the
B.1.351 variant has been consistently difficult to neutralize
following vaccination with the original prototype vaccines,” said
James Brien, Ph.D., Assistant Professor, Molecular Microbiology and
Immunology at Saint Louis University. “If the simple addition of an
AdCOVID booster dose is able to provide effective coverage against
variants of concern it would greatly simplify our response to the
challenge presented by this virus by eliminating the need to
develop new variant adapted vaccines.”
Importantly, AdCOVID also promoted a strong
mucosal neutralizing response to the B.1.351 virus in the
respiratory tract with bronchoalveolar lavages showing
neutralization of the variant virus. These preclinical data suggest
that vaccination with AdCOVID leads to a cross-neutralizing
antibody response both systemically and locally within the
respiratory tract that can effectively neutralize the B.1.351
virus.
“We believe that our selection of the RBD of the
spike protein as the vaccine antigen was key in obtaining these
impressive results,” said Scot Roberts, Ph.D., Chief Scientific
Officer at Altimmune. “From a neutralization perspective, AdCOVID
is designed to focus the immune response on RBD, the most important
part of the SARS-CoV-2 virus. The likely result is the development
of antibodies to sub-dominant or cryptic neutralizing epitopes not
readily recognized when presented in the context of the entire
spike protein, which is targeted by most other vaccine
candidates.”
About AdCOVID
AdCOVID is a single-dose intranasal vaccine
candidate for COVID-19 currently being evaluated in a Phase 1
clinical trial. It is designed to stimulate a broad immune response
including both systemic immunity (neutralizing antibody) and local
immunity (mucosal IgA, resident memory T cells) in the nasal cavity
and respiratory tract.
In published preclinical studies
(www.biorxiv.org/content/10.1101/2020.10.10.331348v1) conducted in
collaboration with the University of Alabama at Birmingham, potent
serum neutralizing antibody responses, T cell responses, and a
robust induction in mucosal immunity were observed in mice
following a single intranasal dose of AdCOVID. Mucosal immunity was
characterized by IgA antibody and resident memory T cell responses
in the respiratory tract, both of which are believed to be
important in fighting infection, and importantly, transmission. In
preclinical efficacy studies, AdCOVID provided 100% protection
against lethal SARS-CoV-2 challenge.
Based on data from Altimmune’s other intranasal
platform vaccine candidates, AdCOVID is expected to have extended
stability at room temperature that would allow for cold chain-free
shipment of the vaccine. If demonstrated, AdCOVID could be stored
in the common refrigerators found in community-based doctors’
offices and pharmacies for two years or more. The Company believes
that these simple and convenient handling requirements, together
with the potential ability to block SARS-CoV-2 transmission, could
position AdCOVID as a leading intranasal COVID-19 vaccine.
About Altimmune
Altimmune is a clinical stage biopharmaceutical
company focused on developing intranasal vaccines, immune
modulating therapies and treatments for liver disease. Our diverse
pipeline includes proprietary intranasal vaccines for COVID-19
(AdCOVID™), anthrax (NasoShield™) and influenza (NasoVAX™); an
intranasal immune modulating therapeutic for COVID-19 (T-COVID™);
and next generation peptide therapeutics for NASH (ALT-801) and
chronic hepatitis B (HepTcell™). For more information on Altimmune,
please visit www.altimmune.com.
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Forward-Looking Statement
Any statements made in this press release
relating to future financial or business performance, conditions,
plans, prospects, trends, or strategies and other financial and
business matters, including without limitation, the timing of key
milestones for our clinical assets, the timing of the data readout
from the AdCOVID Phase 1 clinical trial in June 2021, the potential
immunization effects of AdCOVID, the potential of AdCOVID to block
SARS-CoV-2 transmission, the shipping and storage requirements for
AdCOVID, our ability to manufacture AdCOVID for our clinical trials
and commercial needs, the prospects for regulatory approval of our
product candidates and commercializing or selling any product or
drug candidates, are forward-looking statements within the meaning
of the Private Securities Litigation Reform Act of 1995. In
addition, when or if used in this press release, the words “may,”
“could,” “should,” “anticipate,” “believe,” “estimate,” “expect,”
“intend,” “plan,” “predict” and similar expressions and their
variants, as they relate to Altimmune, Inc. (the
“Company”) may identify forward-looking statements. The Company
cautions that these forward-looking statements are subject to
numerous assumptions, risks, and uncertainties, which change over
time. Important factors that may cause actual results to differ
materially from the results discussed in the forward looking
statements or historical experience include risks and
uncertainties, including risks relating to: potential impacts due
to the COVID-19 pandemic such as delays in regulatory review,
manufacturing and supply chain interruptions, access to clinical
sites, enrollment, adverse effects on healthcare systems and
disruption of the global economy; the reliability of the results of
studies relating to human safety and possible adverse effects
resulting from the administration of the Company’s product
candidates; the Company’s ability to manufacture clinical trial
materials and commercial supply on the timelines anticipated; the
Company’s ability to secure manufacturing approval from its
SARS-CoV-2 cell licensor on the timelines anticipated; and the
success of future product advancements, including the success of
future clinical trials. Further information on the factors and
risks that could affect the Company's business, financial
conditions and results of operations are contained in the Company’s
filings with the U.S. Securities and Exchange Commission,
including under the heading “Risk Factors” in the Company’s annual
report on Form 10-K for the fiscal year ended December 31,
2020 filed with the SEC, which is available
at www.sec.gov.
Altimmune Investor & Media Contacts:
Will Brown |
Stacey Jurchison |
Chief Financial Officer |
Sr. Dir, Investor Relations |
Phone: 240-654-1450 |
Phone : 410-474-8200 |
wbrown@altimmune.com |
sjurchison@altimmune.com |
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