Osivax is developing promising influenza and Covid vaccines

The viruses that cause influenza and COVID-19 are constantly evolving, evading our vaccine defenses. The French company Osivax is developing vaccines that make it harder for viruses to escape.

Many life-saving vaccines have been developed and approved to protect against viral infections, including COVID-19 and influenza. Commercially available vaccines usually activate the production of antibodies against fragments called antigens on the surface of viruses, such as the spike protein in the case of the coronavirus responsible for COVID-19.

However, flu and coronaviruses are capable produce their surface antigens, which makes it difficult for antibodies to fight invaders. This means that Covid booster vaccines are often needed to combat new strains of the pathogen. And in the case of seasonal flu, vaccine manufacturers must predict which strain will be present, which may provide insufficient protection to vulnerable populations.

To get around this problem, Osivax is developing vaccines that activate T cells instead of antibodies against viral antigens. Unlike antibodies, T cells can detect antigens hidden inside viruses, and many of these hidden antigens do not evolve very often.

Antibodies are much easier to target with a vaccine than T cells, according to Delphine Guyon-Gelin, Osivax’s chief business development officer. This is because antibodies can be measured with a simple blood test, while T cells often need to be tested in tissue samples.

“If you can get an antibody-based vaccine that protects and neutralizes the virus well, you don’t have to worry about T cells as much,” Guyon-Ghelin said. However, she added that antibody-based vaccines are generally limited to highly mutating viral infections such as influenza and COVID-19.

Osivax produces recombinant protein vaccines that self-assemble into virus-like particles (VLPs). These VLPs are designed to resemble viruses enough to cause the immune system to attack them, and can activate both antibodies and T cells. By targeting antigens within viruses, Osivax VLP vaccines may provide the future of vaccines against viral infections.

Osivax’s lead program is in phase 2 trials for influenza prevention. So far, the vaccine has shown about 75% protection against two strains of flu in clinical trials.

“The average effectiveness of flu vaccines over the past 10 years has been 40% in adults. In the elderly, it was closer to 30%,” commented Guyon-Gellin. “What we observed in our clinical trial is twice as much.”

If a promising flu vaccine comes to market, it could reduce the risk of getting the flu among the elderly, who are one of the most vulnerable groups to infection. It could also serve as a basic vaccine in future pandemics.

“As we saw with COVID-19, you identify the virus and then you need a little bit of time to make a fully adapted vaccine and deliver it,” Guyon-Guelin said. A core vaccine can help meet vaccine needs until more specific vaccines are available.

To fund the development of the vaccine, Osivax is raising a Series B investment round, with the next clinical step being a Phase 2b trial of its lead influenza candidate, which will begin in 2023. Osivax is also supported by a €10 million grant from Bpifrance, which it received. in June 2022.

In addition to influenza and Covid, Osivax is developing vaccine candidates against latent viral infections such as human papillomavirus (HPV). The firm is also exploring the potential to deploy the technology to treat cancer.

A number of VLP-based vaccines are already widely used to prevent infections such as hepatitis B, HPV and malaria. Osivax chose VLPs because they have some advantages over viral vector vaccines and messenger RNA (mRNA) vaccines. For example, some viral vector vaccines are not well suited for re-immunization, and mRNA vaccines tend to have lower tolerability and duration of action than protein vaccines.

One prime example of the effectiveness of T-cell-targeted vaccines is the Shingrix shingles vaccine. This shows that the strategy has potential, despite how difficult the development may be.

“The best benchmark for T-cell vaccine use may be Shingrix,” Guyon-Ghelin said. “But it’s clearly a new area that’s less explored.”

There are many companies looking for universal, promising influenza and COVID-19 vaccines that T cells are targets. Some examples include Emergex Vaccines and ConserV Bioscience.

However, other attempts against influenza using T-cell vaccines have been unsuccessful. In 2020, Vaccitech abandoned its flu vaccine program after its candidate failed to meet phase 2 trial goals. In Israel, a flu vaccine developed by BiondVax failed to prevent influenza in phase 3 trials.

Guyon-Gellin is confident that Osivax can succeed where others have failed, as his vaccine has shown robust clinical efficacy in independent trials.

The COVID-19 pandemic has increased interest in vaccine technology with mRNA therapeutics reaching the mainstream as a result. While private investment for flu vaccine developers remains limited, Guyon-Ghelin noted that public investors and governments are more willing to fund the development of better flu vaccines.

“During the Covid pandemic, much of the public funding for the fight against influenza was suspended to allocate more resources to the Covid emergency,” said Guyon-Gellin. “We are now seeing these sectors return to public funding.”