The multicenter, double-blind, randomized, placebo-controlled Phase I study was designed to assess the safety and immunogenicity – a patient’s ability to generate an immune response – of four doses (0.3mcg, 1mcg, 3mcg and 10mcg) of the vaccine candidate. The vaccine candidate is comprised of the ectodomain of the viral M2 protein (M2e) fused to the bacterial protein flagellin.
Sixty healthy young volunteers aged 18-49 were randomized to receive the vaccine candidate in dosages of 0.3mcg (six subjects), 1mcg (18 subjects), 3mcg (six subjects), 10mcg (14 subjects), compared to placebo (16 subjects), in two doses injected 28 days apart. Clinical and laboratory safety assessments took place one and seven days after immunization; immune response to M2e and flagellin was assessed at seven, 14 and 28 days after each dose.
The 0.3mcg and 1mcg doses were safe and well tolerated in all subjects and immunogenic in 18 (75%) of 24 vaccinees after the first dose and 23 (96%) after the second dose. In the 1mcg group, the geometric mean M2e antibody concentration was 0.4mcg/ml after the first dose and 1.7mcg/ml after the booster dose. Immune responses to flagellin were also robust and did not appear to negatively affect M2e antibody responses from the booster dose. The two highest doses (three and 10mcg) were associated with the presence of flu-like symptoms in some of the subjects.
Given the strength of the antibody responses and the absence of significant adverse reactions at the two lowest doses (0.3mcg and 1mcg), VaxInnate intends to continue development and clinical evaluation of the vaccine candidate at doses of 1mcg and less.
This first clinical study of VaxInnate’s M2e universal flu vaccine candidate also validates the company’s novel approach to developing and producing flu vaccines, which is based upon a proprietary combination of toll-like receptor (TLR)-mediated immune enhancement and recombinant bacterial production of vaccine antigen, the company said.
David Taylor, chief medical officer of VaxInnate, said: “VaxInnate’s M2e universal flu vaccine candidate has passed a critical initial test. We’re encouraged by these data, which demonstrate that the vaccine is safe and elicits potent immune responses at doses below a microgram of vaccine antigen, and does so without the use of conventional adjuvants.”