Thorax, Vol 69, S2, Abstract P204
British Thoracic Society Winter Meeting, London, 2014
Although most CF patients express CFTR protein (albeit mutant) and should therefore not recognise the wild-type CFTR protein as foreign, there is an inherent risk of activation of T-cells against the recombinant wild-type protein after gene therapy. In addition, we have previously shown that approximately 10% of CF and non-CF subjects carry self-reactive CFTR-specific T-cells (Calcedo et al, Hum Gene Ther Clin Dev 2013). The reason for this is unknown and it is also unclear whether being positive for self-reactive T-cells affects disease severity or increases the risk of further T-cell activation after gene therapy.
As part of the UKCFGTC Phase I/IIa Pilot study [in which patients received a single dose (5, 10 or 20 mls) of the non-viral formulation pGM169/GL67A] peripheral blood mononuclear cells (PBMC) were collected prior to dosing and approximately 4 weeks after nebulisation of 5 ml (n = 2), 10 ml (n = 6) or 20 ml (n = 17) of pGM169/GL67A. IFN-g ELISPOT to detect CFTR-specific T-cells in PBMC was performed. CFTR-specific T-cells were detectable in one patient pre- and post-dosing. In the remaining 18 patients we did not detect CFTR-specific T- cells. In addition we quantified anti-DNA antibodies (anti- nuclear and anti-cytoplasmic) in blood samples taken pre- and approximately 4 weeks post-dosing (n = 7 (5 ml), n = 10 (10 ml) and n = 17 (20 ml). We did not observe any evidence for induction of anti-DNA antibodies after a single dose of pGM169/GL67A.
The UKCFGTC has now completed a Phase IIb multi-dose clinical trial in May 2014 (ClinicalTrials.gov identification number – NCT01621867). CF patients received 12 monthly doses of pGM169/GL67A (115 completed nine or more doses), or placebo by aerosol. PBMC were collected on two occasions prior to dose 1 to establish baseline levels for CFTR-specific T- cells, approximately 4 weeks after Dose 4 or 5, and 2 to 4 weeks after Dose 12 and the ELISPOT was performed. In addition anti- DNA antibodies were quantified.
The Phase IIb trial will be unblinded in Summer 2014 to allow data analysis and all data will be presented at the conference.