A novel peptide-based pan-influenza A vaccine: A double blind, randomised clinical trial of immunogenicity and safety

BACKGROUND: FP-01.1 is a novel synthetic influenza A vaccine consisting of six fluorocarbon-modified 35-mer peptides that encapsulate multiple CD4+ and CD8+ T-cell epitopes and is designed to induce an immune response across a broad population. METHODS: FP-01.1 was evaluated for safety and immunogenicity in a randomised, double-blind, placebo-controlled, dose-escalation, phase I clinical study in healthy adult volunteers (n=49). IFNγ ELISpot assays and multicolour flow cytometry were used to characterise the immune response. RESULTS: FP-01.1 was safe and well tolerated at all doses tested with a similar adverse event profile in actively vaccinated subjects compared with controls. Maximum immunogenicity was in the 150 μg/peptide dose group where a robust response (243 spots/million PBMC) was demonstrated in 75% subjects compared with 0% in placebo controls. All six peptides were immunogenic. FP-01.1 induced dual CD4+ and CD8+ T cell responses and vaccine-specific T cells cross-recognise divergent influenza strains. CONCLUSIONS: This first-in-human study showed that FP-01.1 has an acceptable safety and tolerability profile and generated robust anti-viral T cell responses in a high proportion of subjects tested. The results support the further clinical testing of FP-01.1 prior to clinical, proof-of-concept, live viral challenge studies.