(617c) Activatable Virus Nanoparticles for Cancer Targeting

Adeno-associated virus (AAV) nanoparticles show great promise as gene delivery vectors due to its high safety profile, ability to transduce dividing and non-dividing cells, and its low immunogenicity.  Successful implementation of cancer gene therapy will require a high degree of targeting to minimize destruction of healthy tissue.  A significant body of work has demonstrated that AAV can be retargeted via cell surface receptors.  However, it may be difficult to distinguish cancer cells from normal tissue by the presence of a single biomarker.  We present an adeno-associated virus nanoparticle designed to integrate multiple signals in the tumor microenvironment, which influences the virus’s decision to activate cell-binding and ultimately mediate transduction. The mutant displays drastic changes in heparin affinity and transduction behavior after in vitro treatment by MMP-7.  Heparin affinity chromatography indicates the vector activates to bind its primary cell surface receptor, heparan sulfate proteoglycan (HSPG), after treatment with cancer marker MMP-7.  Western blot analysis confirms the virus is specifically cleaved by this protease.  Strikingly, transduction assays reveal a consistent increase in gene delivery after treatment with MMP-7 in 5 different cell lines: 293T, Cos-7, BT-549, MDA-MB-231, and HeLa.  The greatest increase was in 293T cells at over a log fold increase in GFP positive cells.  No difference was observed for wt capsids in any assay. This work is the first demonstration of an AAV nanoparticle engineered to respond to enzymatic markers of disease. Combined with the redesign of AAV2’s cell binding domain, this strategy may provide the critical advancement necessary to achieve high specificity for cancer therapy.