Production of FVIII in the lungs.

Pytel KM, Paul-Smith M McIntosh J, Chan M, Meng C, Pringle IA, Davies LA, Inoue M, Hasegawa M, Hyde SC, Gill DR, Nathwani AC, Alton EW, Griesenbach U

The British Society of Gene Therapy Annual Conference, Glasgow, 2015

We have previously shown that the lung can be used as ‘‘factory’’ for production of secreted proteins, using Sendai virus-mediated gene transfer, which however could not be re- peatedly administrated due to induction of immune responses. To overcome these issues we developed a lentiviral vector specifically pseudotyped with the Sendai virus envelope proteins F and HN (rSIV.F/HN).

The unique features of rSIV.F/ HN, namely stable expression for >20 months after a single dose and efficient transduction after repeated administration, make the vector an attractive candidate for a large range of disease indications. Here, we first transduced mouse lung with rSIV.F/HN carrying the secreted reporter gene Gaussia luciferase (GLux) or a control virus by nasal instillation (1e6 transduction units (TU)/mouse, n = 5–6/group). Persistent levels of GLux expression were detectable in lung (3 logs above control) and broncho-alveolar lavage fluid (BALF, 4 logs above control) for at least 12 months.

Importantly, even this modest dose of virus led to significant (p<0.01) levels of GLux in serum (274–72 RLU/ul, control: 41–6 RLU/ul) which per- sisted for at least 12 months. Transduction of mouse lung with rSIV.F/HN carrying the FVIII cDNA (1.6e8-3.4e8 TU/ mouse, n = 3–4/group) produced, significant (p < 0.05) and dose-related levels of FVIII in lungs and BALF 10 and 28 days post-transduction. Therapeutically relevant levels (3% of normal) of FVIII were also detectable in plasma 1 month after gene transfer. These data support the concept that rSIV.F/HN-mediated transduction of lungs can produce therapeutically relevant and persistent levels of recombinant protein in blood.