Seattle’s Access to Advanced Health Institute (AAHI) reported positive results of a first-in-human Phase 1 clinical trial demonstrating the safety and immune responses in its temperature-stable tuberculosis vaccine candidate.

AAHI’s TB vaccine combines several proteins from Mycobacterium tuberculosis, the bacterium that causes tuberculosis, into a fusion protein with a proprietary immune-stimulating adjuvant in a freeze-dried formulation that can be stored at elevated temperatures (nearly 100 degrees Fahrenheit) for several months. 

The novel single-vial presentation of this freeze-dried tuberculosis vaccine candidate elicited a stronger immune response than the administration of the same vaccine using separate vials of antigen and liquid adjuvant formulation, according to a press release by AAHI.

“Adjuvanted subunit vaccines have re-energized the field of TB vaccine development. This study represents the first temperature-stable adjuvant-containing subunit TB vaccine candidate to be evaluated in the clinic,” says Christopher Fox, PhD, senior vice president of formulations and principal investigator of the contract awarded by the National Institutes of Health that funded the trial, in a press release. “An effective thermostable TB vaccine would not only be better suited to reach areas of the world most burdened by the disease, but it would also mitigate costs and reduce wastage associated with more stringent cold-chain storage requirements.”

The trial evaluated the safety, tolerability, and immunogenicity of AAHI’s vaccine candidate compared to the previous iteration of the vaccine—a two-vial presentation that had demonstrated promising safety and immunogenicity in Phase 2 clinical testing. 

Notably, the thermostable single-vial presentation induced higher levels of antibodies than the two-vial presentation while retaining the vaccine candidate’s ability to activate “helper T cells” that recruit additional immune cells for a stronger immune response. 

The trial enrolled 48 participants who were to receive two vaccine doses administered intramuscularly 56 days apart, after which the researchers observed the cellular immune response profile thought to be favorable for protection against Mycobacterium tuberculosis.

Additional studies will be needed to scale up manufacturing and establish that the vaccine candidate will protect populations in low-resource communities most burdened by tuberculosis, such as in Southeast Asia and Sub-Saharan Africa, that struggle to maintain even simple refrigeration for vaccine transport and storage, according to a press release by AAHI.

“Equitable access to vaccines has been significantly impeded by cold-chain requirements, and, as observed with COVID-19, no one is safe until everyone is safe,” says Corey Casper, MD, CEO of AAHI. “The development of a safe and immunogenic temperature-stable TB vaccine is a major achievement towards our mission of bringing vaccines to people who most need them, regardless of geography.”

The research and development of the thermostable single-vial TB vaccine candidate received support from multiple partners: National Institutes of Health/National Institute of Allergy and Infectious Diseases, Saint Louis University, Lyophilization Technology Inc, Advanced Biosciences Laboratories, DF/Net Research, and the Center for Biocatalysis and Bioprocessing at the University of Iowa.

Photo caption: Raodoh Mohamath, principal research associate and author, in AAHI’s Laboratories (Photo: Business Wire)