In the studies, the company's second-generation adenoviral vector both induced T-cell activation and generation of antibodies blocking viral replication and clearing existing infection. Immunization with the hAd5-COVID-19 vaccine inhibited viral replication in 10 out of 10 rhesus macaques, as early as the same day of vaccination. The vaccine targets both the inner nucleocapsid and spike proteins to maximize immune responses. Blocking of viral replication was observed in the lung and nasal passages.

The adenoviral vector platform was designed to address the issue of inactivation due to preexisting immunity to many first-generation vectors. ImmunityBio's engineered vector overcomes this problem and effectively delivers its cargo. The hAd5-COVID-19 liquid drug substance is dried (lyophilized) and encapsulated to create the thermally stable oral version of the vaccine.

The company is in discussion with the U.S. Food and Drug Administration to begin a phase I clinical trial of the oral vaccine in a prime, boost regimen in which a subcutaneous boost will also be explored.

The candidate is being developed jointly by ImmunityBio and NantKWest. The research was sponsored by the Biomedical Advanced Research and Development Authority.