Promising protection

Altimmune's AdCOVID vaccine candidate performs well in preclinical models

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Promising protection

GAITHERSBURG, Md.—Early this week, biopharmaceutical company Altimmune, Inc. shared preclinical data for AdCOVID, its single-dose intranasal COVID-19 vaccine candidate. The preclinical studies were performed at the University of Alabama at Birmingham (UAB) and Saint Louis University (SLU), Altimmune's collaborating institutions.

AdCOVID is designed to elicit a broad immune response consisting of both systemic immunity (neutralizing antibody) and local immunity (mucosal IgA, resident memory T cells) in the nasal cavity and respiratory tract. In previous preclinical studies conducted together with UAB, a single dose of AdCOVID led to potent serum neutralizing antibody responses, T cell responses, and a robust induction in mucosal immunity in mice.

“These data are very promising in my view. They show that AdCOVID conferred protection not only against COVID-19 related death, but also against any clinical signs of infection in the mice,” Dr. James Brien, assistant professor of Molecular Microbiology and Immunology at SLU, commented in a press release.

In a K18-hACE2 transgenic mouse model, the researchers demonstrated that a single intranasal dose of AdCOVID resulted in 100-percent protection against a lethal challenge of SARS-CoV-2. In studies conducted at the Department of Molecular Microbiology & Immunology at SLU, all mice dosed with AdCOVID survived with no observed weight loss and mean antibody levels of approximately 1 mg/mL, which implies a robust serum IgG antibody response to the SARS-CoV-2 spike protein. In a study conducted at Dr. Frances Lund's laboratory at UAB in the same mouse model, a single intranasal dose of AdCOVID led to a greater than 1,000-fold reduction in replicating virus in the nasal cavity and respiratory tract following infection with SARS-CoV-2.

In previous work done at UAB, it was found that AdCOVID treatment led to serum IgG and respiratory mucosal IgA titers in mice that were maintained for at least six months, with memory B cells specific for spike antigen found in the lymph nodes 5.5 months after vaccination.

“The data from these preclinical studies only reinforce our high expectations for the ongoing Phase 1 study of AdCOVID launched this quarter,” remarked Dr. Bertrand Georges, chief technology officer at Altimmune. “The complete protection observed in a stringent challenge model combined with inhibition of viral replication and persistent serum and mucosal antibody responses has not previously been demonstrated in preclinical studies for a COVID-19 vaccine candidate and supports our view of AdCOVID as a leading COVID-19 vaccine candidate.”

Altimmune also notes that it expects AdCOVID to have extended stability at room temperature that could allow it to be shipped without cold chain requirements and to be stored in common doctor office refrigerators for two years or more. The company expects to have a data readout for its Phase 1 trial in the second quarter of the year.

This data follows on the heels of an announcement that Altimmune had extended its AdCOVID manufacturing collaboration with Lonza. As per the expanded agreement, Lonza will commission a dedicated manufacturing suite for clinical and commercial production of AdCOVID at its facility near Houston.

“Manufacturing capacity for COVID-19 vaccines has been severely constrained, and this limitation has presented considerable challenges for vaccine developers,” said Dr. Vyjayanthi Krishnan, vice president of Product Development for Altimmune. “By expanding our Lonza collaboration and commissioning our own dedicated manufacturing suite, we are building extra capacity and redundancy into our manufacturing to support potential late-stage clinical trials with AdCOVID and potential future commercial supply. Lonza continues to be an outstanding partner in this mission, and we are pleased to have the opportunity to further our relationship with this world-class team.”

Photo courtesy of Viktor Forgacs on Unsplash

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