Translate Bio presented positive results from a preclinical study of a novel mRNA-based therapeutic designed to treat the pulmonary component of primary ciliary dyskinesia (PCD), a rare genetic disease. Mutations in the genes that cause PCD result in ineffective mucociliary clearance which can lead to lung disease. Study results suggest that delivery of an mRNA-based therapeutic to the lungs can lead to the expression of DNAI1, which could potentially restore mucociliary clearance, the cellular mechanism of the disease. The data are being presented at the American Thoracic Society (ATS) 2021 International Conference and can also be viewed on the Company’s website. PCD is an autosomal recessive disease caused by a genetic mutation that leads to dysfunction of the cilia, which prevents proper mucociliary clearance from the lungs. PCD causes chronic inflammation and pulmonary infection risks which can lead to irreversible lung damage (bronchiectasis) in adulthood including severe impact on quality of life, potential for respiratory failure and, in some cases, the need for lung transplantation. There is no cure for PCD. Disease management is focused on relieving symptoms and slowing the progression of lung damage. While PCD can result from a mutation in one or more of 30+ genes involved in ciliary function, DNAI1 is one of the more frequently mutated genes, accounting for approximately 5–10% of diagnosed PCD cases. Translate Bio designed multiple mRNA sequences to produce functional human DNAI1 using a codon optimization algorithm. The mRNA sequences were screened for DNAI1 protein expression and those sequences producing the highest DNAI1 levels were packaged into proprietary lipid nanoparticles (LNPs) designed for delivery to the lung via nebulization. Data presented include preclinical assessments of the level and distribution of protein expression as well as ciliary activity.