The following is a summary of “Safety and immunogenicity of the H56:IC31 tuberculosis vaccine candidate in adults successfully treated for drug-susceptible pulmonary TB: a phase 1 randomized trial,” published in the April 2024 issue of Infectious Disease by Tait et al.

Researchers conducted a retrospective study assessing the feasibility of using H56:IC31 in future trials by evaluating its safety and immune response in individuals already treated for TB.

They enrolled 22 adults confirmed to be harmful to Mtb by undergoing two GeneXpert tests or two sputum cultures after four to five months of TB treatment. Individuals were also within 28 days of completing their TB treatment. The participants were randomly assigned to receive two doses of the H56:IC31 vaccine (5 mg H56:500 nmol IC31; N=16) or placebo (N=6), with a 56-day interval between doses. Safety and immunogenicity were monitored for 420 days.

The results showed that H56:IC31 vaccination exhibited an acceptable safety profile, primarily characterized by mild, self-limiting injection site reactions. No serious adverse events or vaccine-related severe adverse events were documented. H56:IC31 elicited a CD4⁺ T-cell response targeting Ag85B and ESAT-6, with ESAT-6 being the dominant antigen, which persisted for six months after the final vaccination. Evidence indicated CD8⁺ T-cell responses for both Ag85B and ESAT-6, although to a lesser degree compared to CD4⁺responses.

Investigators concluded that H56:IC31 was safe and induced a robust CD4⁺T-cell response in adults recently cured of uncomplicated pulmonary TB caused by drug-susceptible strains.

Source: academic.oup.com/jid/advance-article-abstract/doi/10.1093/infdis/jiae170/7638461