Efficient gene delivery and expression in pancreas and pancreatic tumors by capsid-optimized AAV8 vectors

M Chen, K Maeng, A Nawab, RA Francois… - Human gene therapy …, 2017 - liebertpub.com
M Chen, K Maeng, A Nawab, RA Francois, JK Bray, MK Reinhard, SL Boye, WW Hauswirth
Human gene therapy methods, 2017liebertpub.com
Despite efforts to use adeno-associated viral (AAV) vector–mediated gene therapy for
treatment of pancreatic ductal adenocarcinoma (PDAC), transduction efficiency remains a
limiting factor and thus improvement of AAV delivery would significantly facilitate the
treatment of this malignancy. Site-directed mutagenesis of specific tyrosine (Y) residues to
phenylalanine (F) on the surface of various AAV serotype capsids has been reported as a
method for enhancing gene transfer efficiencies. In the present studies, we determine …
Despite efforts to use adeno-associated viral (AAV) vector–mediated gene therapy for treatment of pancreatic ductal adenocarcinoma (PDAC), transduction efficiency remains a limiting factor and thus improvement of AAV delivery would significantly facilitate the treatment of this malignancy. Site-directed mutagenesis of specific tyrosine (Y) residues to phenylalanine (F) on the surface of various AAV serotype capsids has been reported as a method for enhancing gene transfer efficiencies. In the present studies, we determine whether Y-to-F mutations could also enhance AAV8 gene transfer in the pancreas to facilitate gene therapy for PDAC. Three different Y-to-F mutant vectors (a single-mutant, Y733F; a double-mutant, Y447F+Y733F; and a triple-mutant, Y275F+Y447F+Y733F) and wild-type AAV8 (WT-AAV8) were administered by intraperitoneal or tail-vein routes to KrasG12D+/−, KrasG12D+/−/Pten+/−, and wild-type mice. The transduction efficiency of these vectors expressing the mCherry reporter gene was evaluated 2 weeks post administration in pancreas or PDAC and correlated with viral genome copy numbers. Our comparative and quantitative analyses of the transduction profiles demonstrated that the Y-to-F double-mutant exhibited the highest mCherry expression in pancreatic tissues (range 45–70%) compared with WT-AAV8 (7%; p < 0.01). We also detected a 7-fold higher level of vector genome copy numbers in normal pancreas following transduction with the double-mutant AAV8 compared with WT-AAV8 (10,285 vs. 1,500 vector copies/μg DNA respectively, p < 0.05). In addition, we observed that intraperitoneal injection of the double-mutant AAV8 led to a 15-fold enhanced transduction efficiency as compared to WT-AAV8 in mouse PDAC, with a corresponding ∼14-fold increase in vector genome copy numbers (26,575 vs. 2,165 copies/μg DNA respectively, p < 0.05). These findings indicate that the Y447+Y733F-AAV8 leads to a significant enhancement of transduction efficiency in both normal and malignant pancreatic tissues, suggesting the potential use of this vector in targeting pancreatic diseases in general, and PDAC in particular.
Mary Ann Liebert