May 21, 2026 —
ReCode Therapeutics presented new clinical data from its RCT1100 inhaled mRNA program at the 2026 American Thoracic Society International Conference, highlighting the first clinical evidence of biological activity for a genetic medicine in primary ciliary dyskinesia, or PCD. The abstract was selected for oral presentation, underscoring the significance of the findings for a rare lung disease with no approved disease-modifying treatments.
PCD is an inherited disorder caused by mutations in more than 50 genes that impair the structure or function of motile cilia. Defective cilia lead to poor mucociliary clearance, chronic respiratory infections, bronchiectasis, and progressive decline in lung function. The disease is estimated to affect at least 1 in 7,500 people, with many patients remaining undiagnosed due to limited screening and disease awareness.
RCT1100 is an inhaled mRNA therapeutic designed to deliver genetic instructions directly to the airway. ReCode uses its SORT LNP platform to enable lipid nanoparticle-mediated mRNA delivery to lung cells. The goal is to restore protein expression and ciliary activity in patients with PCD, thereby improving mucociliary clearance and potentially altering the course of disease.
In the RCT1100-103 Phase 1b trial, conducted across sites in Denmark, Germany, and the United States, 57% of patients achieved meaningful improvement in mucociliary clearance at 12 weeks. Bronchoscopy data confirmed restoration of protein expression and ciliary activity in the airway, with restored protein expression correlated with positive changes in mucociliary clearance. The therapy was reported to be safe and well tolerated, with no serious adverse events.
The RCT1100-103 study builds on earlier clinical work, including a single-dose Phase 1a study in healthy volunteers and PCD patients and a multiple-dose Phase 1b study in patients with PCD. These earlier studies supported the safety and tolerability of RCT1100 across dose levels up to 5 mg administered three times weekly, with no serious adverse events or Grade 3 or higher treatment-emergent adverse events.
ReCode also highlighted a longitudinal observational study of 25 adults with confirmed PCD, which showed consistently low mucociliary clearance values regardless of genotype. These findings support mucociliary clearance as a potentially useful measure for evaluating disease-modifying therapies in future PCD studies.
Together, the data mark an important milestone for inhaled genetic medicine. By demonstrating mRNA delivery, protein expression, ciliary activity, and functional improvement in the human airway, RCT1100 provides early validation for ReCode’s lung-targeted LNP platform and may open a new therapeutic path for patients with PCD.
