Vaccination with a Hybrid 1 (H1) Fusion Protein Combined with a Liposomal Adjuvant (CAF01) Induced Antigen Specific T-cells 3 Years Post Vaccination in a Human Clinical Trial. (VAC7P.971)

Abstract Approximately one third of the world’s population is infected with Mycobacterium tuberculosis. Developing novel vaccines to protect against pulmonary tuberculosis is a public health priority. In this study, a Hybrid 1 (H1) subunit vaccine containing a recombinant fusion protein of Ag85B and ESAT-6 was paired with a two-component CAF01 liposomal adjuvant system developed and manufactured by Statens Serum Institut. A phase I clinical study was performed to evaluate H1:CAF01 in healthy non-BCG vaccinated adult male and female subjects between the ages of 18 and 55 years old. The subjects were randomized into four groups including H1 alone or H1 with 125/25µg, 313/125µg or 625/125µg CAF01 and were vaccinated on study days 0 and 56. PBMCs harvested approximately 150 weeks post vaccination were used to assess antigen specific responses by a 13-color intracellular cytokine staining assay. Vaccination with H1:CAF01 resulted in statistically significant Ag85B-specific CD4 polyfunctional CD154+ T cells compared to H1 alone. ESAT-6 stimulation resulted in detection of CD4 polyfunctional CD154+ T cells responses that were not elevated to a statistically significant extent compared to H1 alone. This is the first demonstration of the persistence of an antigen-specific cellular immune response up to 3 years after vaccination in a clinical trial using H1:CAF01 vaccination.