Design of gene therapy trials in CF patients.

The report of the first CF patients to receive CFTR gene therapy appeared in 1993; since then, there have been over 20 clinical trials of both viral and non-viral gene transfer agents. These have largely been single dose to either nose or lower airway and have been designed around molecular or bioelectrical outcome measures. Both transgene mRNA and partial correction of chloride secretion have been reported, although sodium hyperabsorption has not been improved. The UK CF Gene Therapy Consortium is focussed on a clinical programme to establish whether these proof-of-principle measures translate into clinical benefit. Here, we discuss the considerations in designing such a programme, focusing in particular on our choice of the optimal, currently available delivery method and established and novel outcome measures. We highlight the logistic and regulatory complexities of such a clinical programme and finally, we look to the future and consider possible alternative strategies.