Leyden Labs’ Nasal Spray Offers New Hope in Flu Protection
Influenza viruses cause millions of infections and hundreds of thousands of deaths globally each year, posing a significant threat to public health. The effectiveness of traditional influenza vaccines is limited by factors such as the rapid mutation rate of the virus and the time required for vaccine production. Dutch biotech company Leyden Labs is developing an innovative nasal spray antibody therapy aimed at revolutionizing flu protection.
Leyden Labs’ Innovative Strategy: Broad-Spectrum Protection
Leyden Labs’ core technology centers on developing a broad-spectrum neutralizing antibody designed to provide protection against multiple influenza strains, including influenza A and B. Unlike traditional vaccines, this antibody directly provides ready-made antibodies that quickly neutralize the virus and prevent it from infecting cells, rather than inducing the body to produce an immune response. This approach is potentially less affected by viral mutations and could offer broader and longer-lasting protection.
The company focuses on developing antibodies that target highly conserved regions on the surface of influenza viruses. These regions exhibit less variation between strains, increasing the likelihood that antibodies targeting them will be effective against multiple strains. Leyden Labs’ lead drug candidate is a nasal antibody spray, designed for administration directly into the nose to provide protection at the site of viral entry – the nasal mucosa. Leyden Labs aims to “stop infections early on, at the particularly gate through which they enter.”
Clinical Trial Data: Initial Positive Signs
Leyden Labs has conducted clinical trials to evaluate the safety and effectiveness of its nasal antibody spray. Data published in Science Translational Medicine show that intranasal delivery of broadly neutralizing antibodies can safely achieve and maintain protective levels at the site of viral entry. In two clinical studies involving healthy volunteers, the nasal spray was shown to be safe and well-tolerated, achieving high, sustained concentrations of the antibody CR9114 in the nasal cavity. Importantly, the antibody retained antiviral functionality while residing in the nasal mucosa.
A third study demonstrated that intranasal administration of CR9114 protected non-human primates from influenza infection and viral replication, providing proof-of-concept that antibody levels achieved intranasally can confer meaningful protection. According to Leyden Labs, the data validate the scientific premise of the PanFlu program, which aims to provide broad, immediate protection against influenza.
Advantages and Challenges of Nasal Spray Antibodies
Potential Advantages:
- Quick Onset of Effect: Antibodies provide immediate protection without requiring the body to mount an immune response.
- Broad Spectrum Protection: Antibodies targeting conserved regions may be effective against multiple virus strains.
- Convenient Administration: Nasal spray administration is simple and non-invasive, potentially increasing acceptance.
Potential Challenges:
- Protection Duration: Antibodies have a limited lifespan in the body and may require regular administration to maintain protection.
- Production Cost: Antibody production can be expensive, potentially affecting accessibility.
- Viral Mutations: While antibodies targeting conserved regions are less susceptible to mutations, viruses could still evolve resistance.
Future Development Direction
Leyden Labs is actively advancing the clinical development of its nasal antibody spray and plans to conduct larger clinical trials in the coming years. The company is also exploring applications of its technology to other respiratory viral infections, such as respiratory syncytial virus (RSV) and COVID-19. Leyden Labs is seeking partnerships with pharmaceutical companies to jointly develop and commercialize its products.
In October 2025, Leyden Labs secured €30 million from the European Innovation Council Fund and Invest-NL to support its function.
Summary and Outlook
Leyden Labs’ nasal antibody spray represents a novel strategy for influenza protection. Preliminary data from clinical trials are encouraging. If the spray successfully completes clinical trials and receives regulatory approval, it could develop into a more effective and convenient means of influenza protection, particularly for high-risk groups. Still, challenges related to protection duration, production costs, and potential viral mutations remain and require further research and development. Leyden Labs’ innovative technology offers new hope for influenza protection, but its ultimate success will depend on subsequent clinical trial results and market performance.
Worth a look