Scanning electron micrograph of Mycobacterium tuberculosis bacteria, which cause TB. Credit: NIAID
Key points:
- A freeze-dried, temperature-stable experimental tuberculosis vaccine was found safe and effective in a new study.
- It is the first successful first trial of any TB vaccine candidate in a temperature-stable form.
- Thermostable vaccines are critical in low-resource settings where maintaining cold or frozen vaccines for long periods is essentially impossible.
A clinical trial testing a temperature-stable experimental tuberculosis (TB) vaccine in healthy adults found that it was safe and stimulated both antibodies and responses from the cellular arm of the immune system. A non-temperature stable form of the candidate previously had been tested in several clinical trials; but, this is the first trial of any TB vaccine candidate in a temperature-stable form.
The experimental vaccine, ID93+GLA-SE, was developed by Christopher Fox and scientists at the Access to Advanced Health Institute (formerly the Infectious Disease Research Institute) in Seattle. It is a recombinant subunit vaccine made from four proteins of Mycobacterium tuberculosis bacteria combined with GLA-SE, an immune-stimulating adjuvant. The freeze-dried formulation does not require refrigeration and is mixed with sterile water just prior to injection.
The current trial investigated whether administering temperature-stable vaccine containing both ID93 and GLA-SE in a single vial would be as effective at inducing an immune response as a regimen in which non-thermostable ID93 and liquid GLA-SE are held in two vials and combined prior to injection. A single-vial presentation of a thermostable vaccine would have clear advantages in ease of storage, transport and administration, the investigators note.
For the single-site trial, 23 participants received the thermostable single-vial regimen, while 22 participants received the two-vial, non-thermostable regimen. According to the study results, published in Nature Communications, both vaccine presentations were safe and well-tolerated. But, recipients of the single-vialed thermostable vaccine had robust T-cell responses and produced higher levels of antibodies in the blood than those receiving the non-thermostable two-vial presentation.
“[The] results of this trial demonstrate a proof-of-concept that adjuvant-containing vaccines can be formulated in a freeze-dried single-vial presentation without detrimentally impacting clinical immunogenicity or safety characteristics,” conclude the researchers.