Ethris has dosed the first patient in a Phase 2a clinical trial of ETH47, the company’s lead mRNA-based antiviral candidate targeting virus-induced asthma exacerbations. The study will assess whether intranasal ETH47 can reduce asthma-related symptoms in adults following exposure to rhinovirus, a common trigger for acute attacks.

ETH47 encodes interferon lambda (IFNλ), a protein key to antiviral immunity in the respiratory tract. Delivered via nasal spray using Ethris’ proprietary Stabilized NanoParticle (SNaP) lipid nanoparticle platform, the therapy aims to activate local antiviral defences without systemic exposure, thereby reducing the risk of off-target effects.

The Phase 2a study, being conducted at St. Mary’s Hospital, London, follows a successful Phase 1 trial where ETH47 was found to be safe and well-tolerated across all doses. Results showed strong local induction of IFNλ and activation of antiviral genes, with no detection of the mRNA, protein, or lipid carriers in the bloodstream.

“Dosing the first patient in our Phase 2a trial for ETH47 marks a defining moment for Ethris, as we advance our lead candidate further into clinical development and continue to validate the potential of Ethris’ innovative platform,” said Dr Thomas Langenickel, chief medical officer at Ethris.

“ETH47 stands out as a highly promising candidate with a novel mechanism of action designed to directly strengthen the body’s antiviral defenses in the airways. By targeting viral infections upstream, ETH47 has the potential to fundamentally change the way asthma is managed and reduce the burden of acute attacks.”

Professor Sebastian Johnston of Imperial College London, a scientific advisor to Ethris and director of VirTus Respiratory Research Ltd, added: “After more than three decades investigating the role of respiratory viruses in asthma, it is clear that we need new approaches to address the underlying triggers of asthma exacerbations. Most therapies today focus on managing symptoms or reducing inflammation. There remains a significant unmet need for interventions that directly target viral triggers and boost antiviral defenses in the airways. This is precisely where innovative new approaches like ETH47 could make a real difference for patients and healthcare systems.”

The randomized, double-blind, placebo-controlled trial will enrol 50 adults with asthma who will undergo a rhinovirus challenge before receiving either ETH47 or placebo. The study’s primary endpoint will assess changes in respiratory symptoms using the Lower Respiratory Symptoms Score (LRSS), a validated tool completed by participants twice daily. The goal is to determine whether ETH47 can help patients regain symptom control comparable to that seen in healthy individuals.

If successful, the company plans to advance ETH47 into a broader Phase 2b study to further evaluate its ability to prevent asthma exacerbations and improve patient outcomes.