Inhaled CFTR mRNA Therapy in Cystic Fibrosis: Emerging Opportunities for Pediatric Precision Medicine

Background

Cystic fibrosis (CF) is a life-limiting autosomal recessive disease caused by pathogenic CFTR variants. CFTR encodes an epithelial ion channel regulating chloride and bicarbonate transport and airway surface hydration. CFTR dysfunction produces dehydrated, viscous mucus, impaired mucociliary clearance, chronic infection, and progressive lung damage. CFTR modulators, including elexacaftor/tezacaftor/ivacaftor, improve the function or processing of specific mutant CFTR proteins but remain genotype-dependent, leaving approximately 10% of people with CF without an effective modulator option. Inhaled CFTR messenger RNA (mRNA) replacement offers a potentially mutation-agnostic approach by delivering temporary instructions for functional CFTR production directly to airway epithelial cells.

Methods / Case Presentation

A narrative literature review of recent PubMed-indexed clinical and preclinical studies was conducted focusing on inhaled CFTR mRNA replacement, lipid nanoparticle (LNP) delivery, pulmonary targeting, and non-viral RNA therapeutics. Studies were evaluated for delivery efficiency, restoration of CFTR function, mucociliary clearance, safety, and translational potential, emphasizing advances relevant to pediatric precision medicine.

Results / Findings

The first-in-human randomized phase 1/2 study of aerosolized MRT5005 included 42 adults with CF. Ten participants experienced at least one febrile reaction, accounting for 14 events overall, and two experienced hypersensitivity reactions. No consistent improvement in forced expiratory volume in one second (FEV1), a standard measure of lung function, was demonstrated, establishing feasibility but not clinical efficacy. More recent strategies have focused on improving mRNA delivery to airway cells using LNPs, which protect mRNA and facilitate cellular uptake. Peptide-functionalized LNPs selected through phage display increased reporter activity up to 7.8-fold in CF bronchial epithelial cultures and 3.4-fold in mouse lungs compared with untargeted LNPs. Preclinical LUNAR-CFTR, an LNP containing codon-optimized human CFTR mRNA, restored CFTR-mediated ion transport in polarized CF human bronchial epithelial models to levels comparable to elexacaftor/tezacaftor/ivacaftor and increased mucociliary clearance approximately threefold in CF ferrets after a single dose.

Discussion & Conclusion

The field has progressed from first-in-human feasibility toward increasingly efficient and targeted pulmonary mRNA delivery. These findings support CFTR mRNA replacement as a potentially mutation-agnostic strategy, particularly for patients who cannot benefit from existing CFTR modulators. However, major barriers remain, including penetration of airway mucus, efficient epithelial uptake, intracellular release of mRNA, transient protein expression, immunologic tolerability, the need for repeat dosing, and translation of preclinical findings into meaningful clinical outcomes. Earlier restoration of CFTR function could theoretically benefit children before irreversible structural lung disease develops, but pediatric efficacy and long-term safety remain unestablished. Continued optimization of LNP delivery and prospective clinical evaluation are required before inhaled CFTR mRNA replacement can become a validated pediatric precision-medicine strategy.