ENA Respiratory has announced the initiation of the Phase 2 POSITS trial of its INNA-051 once-weekly antiviral nasal powder. In April 2025, ENA announced that researchers at the University of Maryland would conduct a Phase 2 trial of the intranasal anti-viral during the 2025/2026 flu season. In October 2025, the company announced that it had raised more than $22 million to support the POSITS study.
The study is expected to enroll as many as 1,100 participants who are likely to be exposed to respiratory viruses due to work and/or housing conditions. In the first part, 200 participants will receive either INNA-051 or a dry powder nasal placebo once a week for 4 weeks during the current flu season, with an additional 900 participants taking part in the 12-week second part the following year.
Development of INNA-051 has been partially supported by the US Department of Defense, and the trial is recruiting participants from a naval medical research center in Maryland. Non-profit organization Flu Lab also provided funding for Phase 2 development of the nasal powder.
ENA Respiratory CEO Christophe Demaison commented, “The start of the POSITS study is an important next step for ENA Respiratory and for the development of INNA-051. Our previous pre-clinical and clinical work has shown INNA-051 to have the potential to shorten the duration of symptomatic infections, prevent progression to the lungs, and reduce complications.”
Demaison added, “There were over a million hospitalizations and up to 200,000 deaths in the US in 2025 from respiratory-related viral infections in such patients last year. By boosting the body’s natural host defense pathways INNA-051 could offer a new option for millions of vulnerable patients worldwide and this study is an opportunity to add significantly to our evidence of its potential.”
Read the ENA Respiratory press release
