The overall goal of this project is to construct smart oncolytic adenovirus (Ad) with designed polymer which can be administered systemically to treat primary and metastatic cancer. We have demonstrated that this efficient systemic delivery of Ad overcome the obstacles associated with immune reaction, short blood circulation time and poor tumor targeting of Ad. Oncolytic Ad has been well-known to selectively replicate in and kill tumor cells, while sparing normal cells. As oncolytic Ad genome including therapeutic transgene cassette replicates in cancer cells, the level of cancer- killing effect can be maximized by amplification of therapeutic gene as well as Ad replication-mediated oncolysis. c-Met-specific shRNA-expressing oncolytic Ad (RdB/shMet) will be generated and characterized for additive therapeutic efficacy through viral oncolysis and long lasting siRNA-mediated silencing of c- Met. Bioreducible polymer, arginated cystamine bisacrylamide hexyl (ABP) will be pegylated and conjugated with tumor-targeting peptides (ABP-PEG-Peptide). Surface of RdB/shMet oncolytic Ad will then be conjugated with ABP-PEG-Peptide to improve systemic delivery by enabling oncolytic Ads to evade capture by immune cells and antibodies. After physical characterization of ABP-PEG-Peptide-conjugated oncolytic Ad, tumor- homing peptide-dependent cell entry and tumor-specific killing efficacy will be evaluated. Therapeutic efficacy and safety profile of smart oncolytic Ad nanocomplex will be assessed in orthotopic tumor models which represent a clinically relevant tumor model. Immune response against Ad, liver toxicity, blood clearance profile, and body distribution profile will be assessed. Polymer-shielded and tumor-targeted oncolytic Ad nanocomplex may have a synergistic therapeutic effect due to features of its replicating system of Ad and systemic delivery of polymers. ABP-PEG-Peptide- conjugated oncolytic Ad may evade neutralizing anti-Ad Abs and decreases both liver accumulation and interaction with blood components, which results in extended blood circulation time after intravenous injection. In addition, cancer-specific targeting can be significantly improved by EPR-mediated passive targeting as well as tumor-specific peptide-mediated active targeting. More importantly, oncolytic Ad can keep continuously replicating and infecting neighboring tumor cells after tumor-selective infection, ultimately enhancing therapeutic value. Further, the restricted selectivity to tumor cells reduces toxicity of normal cells, making it possible to treat primary and metastatic lesions via systemic delivery.
The proposal presents a new paradigm for the design of oncolytic Ad nanocomplex that allows systemic administration by reduction of Ad-specific immune response and increase of blood circulation profile. This approach will explore the potential to combine the complementary characteristics of viral and nonviral vectors into a single vector, overcoming the limitations of both viral and nonviral vectors. The obtained results will support to move toward clinical application.
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