EVALUATION OF SAFETY AND GENE EXPRESSION WITH A SINGLE DOSE OF PGM169/GL67A ADMINISTERED TO THE NOSE AND LUNG OF INDIVIDUALS WITH CF: THE UK CF GENE THERAPY CONSORTIUM "PILOT STUDY"

The UK CF Gene Therapy Consortium is working towards a multidose gene therapy study, using the best currently available non-viral gene delivery complex, and whose end point will be to detect clinical benefit rather than proof-of-principle. Based on extensive preclinical testing our selected product is pGM169, a CpG-free human CFTR (cystic fibrosis transmembrane conductance regulator) plasmid with a CpG-free cytomegalovirus (CMV) enhancer and human elongation factor 1a (hCEFI) promoter complexed with GL67A (GL67, DOPE and DMP-PEG5000). We are currently undertaking a single dose study because of a requirement to confirm safety of this ''first-in-man'' product; however, study design has also been tailored to assess gene expression in vivo in cystic fibrosis (CF) lungs. A single nebulised dose of 20 ml (53 mg of pGM169 and 286 mg of GL67A) is delivered by an Aeroeclipse II breath-actuated device; a nasal dose (10% of the nebulised volume) is administered on the same occasion using a standard nasal spray device. The latter allows assessment of gene expression without the sampling issues inherent in lower airway assessment, as well as anchoring to our previous clinical trials. Safety measures include physical examination, lung physiology (spirometry, pulse oximetry, lung clearance index), systemic and sputum inflammatory markers, renal and hepatic function and chest CT. We are also measuring antinuclear and antidouble-stranded DNA antibodies, and specific CFTR-related T cell responses. Measurements are made at intervals prior to dosing and during a 28-day follow-up period. Gene expression is assessed by (1) quantitative Taqman RT-PCR for transgene mRNA on nasal and bronchial brushings; (2) anti-CFTR immunohistochemistry; and (3) nasal and lower airway potential difference measurements. Given intersubject variability, paired measurements on individuals will be obtained; bronchoscopies are being performed prior to dosing and at two time points postdosing. Nasal potential difference is measured on serial visits. To date, 3 patients in an initial non-bronchoscopic cohort have received a half dose of 10 ml and 3 have received the full 20 ml dose. The Data Safety Monitoring Board has granted permission to proceed further with 20 ml dosing, and available data will be presented on safety, tolerability and gene expression.