The UK Respiratory Gene Therapy Consortium has developed a highly efficient lentiviral vector for CF gene therapy. A first-in-man trial will test safety and mechanistic efficacy using nasal administration. This work evaluates novel and improved safety and efficacy outcome assays to maximise the impacts of the trial.
Nasal cytokines inform on inflammatory responses following vector administration. A panel of ten relevant nasal cytokines were identified, and harvested from people with CF and healthy controls using sponges. IL-1β and IL-8 were quantifiable in most cases. Median concentrations were similar in CF and control participants, and remained stable on repeated visits in CF.
The development of vector-neutralising antibodies following treatment may reduce efficacy of repeat doses and must be evaluated in the trial. ELISA and cell-based neutralisation assays were evaluated for this purpose. There was no loss of detection or neutralising function of antibodies through sponge collection or following storage at -80°C.
Peak nasal inspiratory flow (PNIF) could inform on early inflammatory responses to nasal administration of the agent. PNIF was assessed to be repeatable on separate visits with similar values to a healthy control group.
Assessment of viral shedding is an important safety consideration. A digital PCR assay was assessed to be sufficiently sensitive to detect relevant shedding in urine and saliva and freezing did not affect recovery.
Efficacy has been difficult to assess in nasal gene therapy trials with optimal cell sampling techniques debated. Here, nasal brushing was found superior to curettage for harvesting CFTR-expressing cells. An RNA in situ hybridisation assay was used to reliably detect lentiviral transduction in vitro and in vivo. Objective quantification of cellular transduction was performed using a custom-designed programme.
These studies characterise new outcome measures and lay the framework for a rigorous nasal assessment of the lentiviral vector for the CF gene therapy trial.