Ethris nasal mRNA spray ETH47 lowers rhinovirus peak load 40-fold in Phase 2a asthma trial

Munich-based Ethris GmbH announced topline Phase 2a data on November 5, 2026 for ETH47, an intranasal mRNA encoding interferon lambda (IFNλ), in adults with asthma, according to techtimes.com techtimes.comtechtimes.comtechtimes.comOpen source ↗. The randomized, double-blind, placebo-controlled study enrolled 50 adults with mild-to-moderate asthma. A single dose given one day before a controlled rhinovirus challenge was associated with a 40-fold lower peak viral load on Day 2, a 58% lower lower respiratory symptom score (LRSS) area under the curve, 65% less rescue medication use, a 53% lower Jackson Cold Score and a 37% lower proportion of participants developing a full cold. No serious adverse events were reported.

Ethris did not report p-values or statistical significance for any outcome and describes the results as numerical reductions. A Phase 2a trial of 50 participants is not powered to establish significance for primary endpoints. In the subgroup with higher IFNλ concentrations in nasal lining fluid, viral load on Days 2 and 3 was more than 100-fold lower, peak viral load was 19-fold lower and peak LRSS was 46% lower.

Challenge-study design

The study (ISRCTN21576805) used a controlled human infection model. It was run by VirTus Respiratory Research Ltd. with Prof. Sebastian Johnston of Imperial College London as principal investigator, at the hVIVO quarantine unit at St. Mary's Hospital in London. Participants received ETH47 or placebo on Day -1 and were inoculated intranasally with rhinovirus A16 on Day 0. The primary endpoint was LRSS area under the curve; secondary endpoints were viral load, Jackson Cold Score, rescue medication use and the proportion of participants developing a cold. The first patient was enrolled in August 2025, enrollment was completed in July 2026, and final data were collected by August 15, 2026.

Interferon lambda mechanism

The rationale rests on a 2006 Nature Medicine paper by Contoli, Johnston and colleagues, which found that airways of people with asthma produce less interferon lambda after rhinovirus infection than those of healthy individuals techtimes.comtechtimes.comtechtimes.comOpen source ↗. No FDA-approved antiviral or vaccine for rhinovirus exists, and more than 160 serotypes circulate, so ETH47 targets the host rather than the virus.

ETH47 is built on the SNIM®RNA platform, which uses modified nucleotides and HPLC purification to remove double-stranded RNA contaminants. It is formulated in the SNaP® lipid nanoparticle, designed to withstand nasal spray delivery and penetrate the mucus layer. Airway cells that take up the mRNA secrete IFNλ locally; it binds IFNLR1 and IL10RB on neighboring epithelial cells and activates the JAK-STAT pathway and interferon-stimulated genes such as IFIT1, MX1 and OAS3.