GAITHERSBURG, Md., Aug. 25, 2020 (GLOBE NEWSWIRE) -- Altimmune, Inc. (NASDAQ:ALT), a clinical-stage biopharmaceutical company, today announced additional positive results from the preclinical studies of its single-dose intranasal COVID-19 vaccine candidate, AdCOVID. The studies were conducted as part of Altimmune's ongoing collaboration with the University of Alabama at Birmingham (UAB).
The latest study showed potent stimulation of antigen-specific CD4+ and CD8+ T cells in the lungs of CD-1 mice as early as 10 days following a single intranasal vaccination, with responses strongly biased toward CD8+ T cells. The mucosal T cell response in the respiratory tract is believed to be dependent on the intranasal route of administration and we believe it has the potential to provide additional protection against COVID-19. The induction of a mucosal T cell response in the lungs has not been shown, to date, with the intramuscularly administered COVID-19 vaccine candidates that are currently in the advanced stages of clinical development. Both CD4+ and CD8+ T cells displayed phenotypes consistent with the Th1 type immune response that is important for control of viral infections. CD8+ T cells, also known as killer T cells, can recognize and kill virally infected cells, and recent clinical reports in China and Europe have suggested the importance of T-cell responses in long-term protection from COVID-19.
On July 13, the Company reported results from the initial studies at UAB that showed that AdCOVID stimulated a strong systemic neutralizing antibody response in addition to a 29-fold mucosal IgA antibody response against the spike protein in the respiratory tract. Additional data from CD-1 mice analyzed since the July 13 announcement showed mean serum neutralization titers 4-weeks after a single intranasal dose exceeded 1:400 in a foci reduction neutralization assay against wild-type SARS-CoV-2 virus. The Company is currently manufacturing AdCOVID for a Phase 1 safety and immunogenicity study expected to begin in Q4 2020.
"The property that sets AdCOVID apart is that it has been shown preclinically to induce a potent T cell and IgA antibody response in the lungs, in addition to the systemic neutralizing antibody response induced by intramuscular vaccine candidates," said Dr. Frances Lund, Charles H. McCauley Professor and Chair, Department of Microbiology at UAB, and lead investigator for preclinical testing of the AdCOVID vaccine candidates. Dr. Lund added, "This local mucosal immune response is an important addition to the systemic immune response and has the potential to block infection and prevent transmission."
In addition to the potent immunogenicity results in mice after a single dose administration, AdCOVID is expected to confer additional practical benefits related to vaccine distribution and administration. Intranasal dosing provides AdCOVID with the potential to be administered rapidly and without the need for needles, syringes or trained healthcare personnel. In addition, AdCOVID's expected room temperature stability profile may allow for broad distribution of the vaccine without the need for expensive cold-chain logistics, such as refrigeration or freezing.