Durational Study of Persistent Transduction of Rhesus Macaque Lung and Other Organs Following Single Dosing with AAV1-CFTR

Adeno-associated virus (AAV)–mediated gene transfer remains a promising strategy for cystic fibrosis (CF), but durability of expression and optimal dosing intervals are unresolved challenges. Here, we evaluated long-term gene transfer, transduction, and immunological responses following a single pulmonary administration of an AAV1 vector encoding Δ27–264 CFTR to juvenile rhesus macaques. Four animals received 1 × 10 ¹ ³ vector genomes via endotracheal spray. Two were untreated. All were analyzed 180 days post-delivery. Vector genomes were detected throughout the conducting airways and distal lung at levels ranging from ∼5 × 10 ⁶ to 9 × 10 ⁷ vg/µg genomic DNA. Vector genomes were also detected in extrapulmonary tissues, including liver, pancreas, spleen, heart, and kidney. Cystic fibrosis transmembrane conductance regulator (CFTR) messenger RNA expression was detected in all tissues examined and in several respiratory and extrapulmonary tissues, accompanied by increased CFTR protein expression in multiple tissues. Transgene expression was observed in airway basal cells and FOXI1-positive ionocytes, indicating targeting of key epithelial and progenitor cell populations. Despite persistence of vector genomes, immune activation was limited. Cytokine and chemokine expression profiles showed only sporadic, tissue-specific changes without evidence of coordinated inflammation. Neutralizing antibodies to AAV1 developed in all animals but did not correlate with capsid-specific T cell responses, which remained low and infrequent. These findings indicate sustained gene transfer and transduction for at least 180 days following a single AAV1 administration to the primate lung, with minimal immunopathology. The durability of expression supports the potential feasibility of extended dosing intervals and informs the development of repeatable AAV-based gene therapies for CF.