rAAV-CFTRΔR Rescues the Cystic Fibrosis Phenotype in Human Intestinal Organoids and CF Mice

RATIONALE: Gene therapy holds promise for a curative mutation-independent treatment applicable to all cystic fibrosis (CF) patients. The various viral vector-based clinical trials conducted in the past have demonstrated safety and tolerance of different vectors, but none have led to a clear and persistent clinical benefit. Recent clinical breakthroughs in adeno-associated virus-(rAAV) based gene therapy encouraged us to re-explore a rAAV approach for CF.

OBJECTIVES: We evaluated the preclinical potential of rAAV gene therapy for CF to restore chloride and fluid secretion in two complementary models: intestinal organoids derived from CF subjects and a CF mouse model, an important milestone towards the development of a clinical rAAV candidate for CF gene therapy.

METHODS: We engineered a rAAV vector containing a truncated CFTR (CFTRΔR) combined with a short promoter (CMV173) to ensure optimal gene expression. A rescue in chloride and fluid secretion after rAAV-CFTRΔR treatment was assessed by forskolin-induced swelling in CFTR-deficient organoids and by nasal potential differences in ΔF508 mice.

MEASUREMENTS AND MAIN RESULTS: rAAV-CFTRΔR transduction of human CFTR-deficient organoids resulted in forskolin-induced swelling indicating a restoration of CFTR function. Nasal potential differences demonstrated a clear response to low chloride and forskolin perfusion in the majority of rAAV-CFTRΔR treated CF mice.

CONCLUSIONS: Our study provides robust evidence that rAAV-mediated gene transfer of a truncated CFTR functionally rescues the CF phenotype across the nasal mucosa of CF mice and in patient-derived organoids. These results underscore the clinical potential of rAAV-CFTRΔR in offering a cure for all CF patients in the future.