March 10, 2020
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Universal flu vaccine shows promise in phase 2b trial

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A single dose of a universal influenza vaccine, adjuvanted FLU-v, may provide prolonged protection against multiple strains of the influenza virus, according to results of a phase 2b trial published in the Annals of Internal Medicine.

“FLU-v is a universal influenza vaccine that targets conserved regions of the flu virus, and therefore should provide protection against all circulating strains and new emergent strains of flu virus without having to change the composition of the vaccine antigens,” Olga Pleguezuelos, PhD, chief scientific officer at SEEK, told Healio Primary Care. “This means that the vaccine could be manufactured all year round and vaccinations will not be limited from September to November and to only groups at risk as it is with the seasonal flu.”

Pleguezuelos and colleagues conducted a randomized, double-blind, placebo-controlled phase 2b trial to evaluate FLU-v (Imutex) — a combination of four synthetic peptides from conserved regions matrix-1, matrix-2 and nucleoprotein inuenza proteins — at one site in the Netherlands. The vaccine, according to researchers, was designed to induce humoral and cell-mediated immunity and protect against A and B strains of influenza.

Within the study, 175 healthy adults were randomly assigned to subcutaneously receive 0.5 mL of nonadjuvanted FLU-v (NA-FLU-v), adjuvanted FLU-v (A-FLU-v), nonadjuvanted placebo (NA-placebo) or adjuvanted placebo (A-placebo).

 

The researchers evaluated vaccine-specific cellular responses at day 0, 42 and 180 using cytometry and an enzyme-linked immunosorbent assay. They collected solicited information on adverse events 21 days after vaccination through diary cards completed by patients. They also collected unsolicited information on adverse events throughout the study period.

On days 42 and 180, the researchers compared changes in cellular immune response with FLU-v vs. placebo to day 0 by evaluating Th1 cytokine production.

The most common adverse events that Pleguezuelos and colleagues observed were mild to moderate injection site reactions.

The difference in median fold increase in secreted interferon gamma between A-FLU-v and A-placebo was 38.2-fold (95% CI, 4.7-fold to 69.7-fold) at day 42 and 25-fold at day 180 (95% CI, 5.7-fold to 50.9-fold).

At day 42, the difference in median fold increase between A-FLU-v and A-placebo was 4.5-fold (95% CI, 2.3-fold to 9.8-fold) for interferon gamma CD4+ T cells and 4.9-fold (95% CI, 1.3-fold to 40-fold) for tumor necrosis factor. There was a seven-fold (95% CI, 3.5-fold to 18-fold) difference for interleukin-2 and 1.7-fold (95% CI, 0.1-fold to 4-fold) difference for CD107a.

Pleguezuelos and colleagues did not observe a difference between NA-FLU-v and NA-placebo.

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During follow-up, 17 of the 47 participants who were swabbed tested positive for influenza. H3N2 was the dominant strain. The researchers determined the overall efficacy for A-FLU-v was 37% (95% CI, –76% to 77%), and the overall efficacy for NA-FLU-v was 67% (95% CI, –17% to 91%). However, the researchers noted that the study was not powered to determine efficacy and a phase 3 trial is needed.

“We are exploring options for the FLU-v vaccine programme and are scheduling meetings with key regulatory authorities, FDA and EMEA, hoping to gain further insight into phase 3 preparation,” Pleguezuelos said. “Phase 3 influenza trials are large (10,000 subjects) and costly and funding is obviously an important hurdle for a small biotech like ours to overcome.” – by Erin Michael

Disclosures: Pleguezuelos reports being an employee of SEEK but does not have shares in the company. FLU-v is currently owned by Imutex, which is 51% SEEK and 49% hVIVO. Please see the study for all other authors’ relevant financial disclosures.