Repeat or single-dose lentiviral vector administration to mouse lungs? It’s all about the timing

Abstract

Lentiviral vectors are attractive delivery vehicles for cystic fibrosis gene therapy owing to their low immunogenicity and ability to integrate into the host cell genome, thereby producing long-term, stable gene expression. Nonetheless, repeat dosing may be required to increase initial expression levels, and/or boost levels when they wane. The primary aim of this study was to determine if repeat dosing of a VSV-G pseudotyped LV vector delivered into mouse lungs is more effective than a single dose. C57Bl/6 mouse lungs were conditioned with lysophosphatidylcholine, followed one-hour later by a LV vector carrying the luciferase reporter gene, using six different short-term (≤1 wk) and long-term (>1 wk) dosing schedules. Luciferase expression was quantified using bioluminescence imaging over 12 months. Most dosing schedules produced detectable bioluminescence over the 12-month period, but the shorter intervals (≤1 wk) produced higher levels of flux than the longest interval (five doses at least 1-month apart). Ex vivo lung analysis at 12 months showed that the estimated mean flux for the group that received two doses 1-week apart was significantly greater than the single dose group and the two groups that received doses over a period greater than 1-week. These results suggest that early consecutive multiple doses are more effective at improving gene expression in mouse lungs at 12 months, than longer repeat dosing intervals.

Genetic therapies in cystic fibrosis

“…Recent efforts in lentiviral drug development, including dosing strategies, continue to support increasing promise. Using luciferase bioluminescence as an efficacy read-out, Donnelley et al recently administered a lentiviral vector to murine lungs, either as a single dose, or by split dosing in which smaller amounts were delivered repeatedly at various intervals [18]. Higher bioluminescence flux was achieved if the dose was split into two sub-doses a day apart, but extra splitting had no significant additional benefit.…”