534. Preparation for a First-in-Man Lentivirus Trial in Cystic Fibrosis Patients

Abstract

Background: We have recently shown that non-viral gene therapy can stabilise the decline of lung function in cystic fibrosis (CF) patients. However, the effect was modest, and it is important to develop more potent gene transfer agents in parallel. F/HN-pseudotyped lentiviral vectors are more efficient for lung gene transfer than non-viral vectors in pre-clinical models. In preparation for a first-in-man CF trial using the lentiviral vector we have undertaken key translational pre-clinical studies. Methods: Regulatory-compliant vectors carrying a range of promoter/enhancer elements were assessed in mice and human air liquid interface cultures to select the lead candidate; CFTR expression and function were assessed in CF models (knockout mice and human intestinal organoids) using this lead candidate vector. Toxicity was assessed and “benchmarked” against the leading non-viral formulation recently used in a Phase IIb clinical trial. Integration site profiles were mapped and transduction efficiency determined to inform clinical trial dose-ranging. The impact of pre-existing and acquired immunity against the vector and vector stability in several clinically relevant delivery devices was assessed. Results: A hybrid promoter consisting of the elongation factor 1α promoter and the CMV enhancer was most efficacious in both murine lungs and human air liquid interface cultures. The efficacy, toxicity and integration site profile supports further progression towards clinical trial and pre-existing and acquired immune responses do not interfere with vector efficacy. The lead rSIV.F/HN candidate expresses functional CFTR and the vector is stable in clinically relevant delivery devices. Conclusions: The data support progression of the F/HN pseudotyped lentiviral vector into a first-in-man CF trial due to start in Q2 2017. Regulatory-compliant toxicology studies are currently being performed.