A clinical trial testing a freeze-dried, temperature-stable experimental tuberculosis (TB) vaccine in healthy adults found it was safe.
A phase 1 trial, supported by the National Institute of Allergy and Infectious Diseases (NIAID) has found that a temperature-stable experimental TB vaccine in healthy adults was safe and stimulated both antibodies and responses from the cellular arm of the immune system.
This trial was the first to test a TB vaccine candidate in a temperature-stable (thermostable form), and the results are published in Nature Communications.
Developing a temperature-stable TB vaccine
The experimental TB vaccine called ID93+GLA-SE was developed by Christopher B Fox, PhD, 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 before injection. Thermostable vaccines are desirable in settings where maintaining cold or frozen vaccines for long periods can be costly and difficult.
The trial explored whether administering temperature-stable TB vaccines that contain 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 before injection. A single-vial presentation of a thermostable vaccine would have clear advantages in ease of storage, transport and administration, the investigators noted.
The vaccine was safe and well-tolerated
The researchers conducted a clinical trial whereby 23 participants received the thermostable single-vial regimen, and 22 participants received the two-vial, non-thermostable regimen. Both vaccines were safe and well-tolerated. However, participants of the thermostable TB vaccine had robust T-cell responses and produced higher levels of antibodies in the blood than those receiving the non-thermostable two-vial vaccine.
Limitations were noted in this small trial. For example, no established correlates of protection define what immune responses are required for vaccine-induced protection from TB disease. Therefore, it is not possible to say whether the enhanced immune responses seen in the thermostable vaccine formulation would translate to improved protective vaccine efficacy. They concluded that the results 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.”