Targeted Exosome-Associated AAV-Mediated Gene Therapy to Eliminate Metastatic Neuroendocrine Cancers

ABSTRACT Neuroendocrine (NE) malignancies are hormone secreting neoplasms that arise from endocrine and nervous system. Multiple NE tumors (NETs) have been diagnosed, such as pancreatic neuroendocrine cancers, medullary thyroid cancers, and pulmonary neuroendocrine carcinoids. Most NE cancer patients are metastatic at the time of initial diagnosis which makes the complete resections via surgery impossible. The current chemotherapies, including Octreotide, Sunitinib, Everolimus and peptide receptor, have marginal curative benefits and severe side effects. Thus, an effective targeted therapy is critical for patients with metastatic NE cancers. We have recently developed a novel technique, named “mitochondrial chemo-optogenetics”, by expressing a heterologous light-gated channelrhodopsin protein in the IMM of cancer cells, and depolarizing IMM potentials and inducing cell death by using luciferase-luciferin bioluminescence as the endogenous light source. Our preliminary data showed that this new mitochondrial gene therapy caused substantial NE cancer cell death in vitro and stopped NE tumor growth and even reduced tumor size in a subcutaneous NE cancer xenograft mouse model. Additionally, we have built an innovative NE cancer-targeted gene delivery platform by tagging our new anti-somatostatin receptor 2 (SSTR2) monoclonal antibody (mAb) to the surface of exosome. However, a targeted gene therapy, such as mAb-Exo-AAV carrying our mitochondrial chemo-optogenetics therapeutic gene, is urgently needed to achieve substrate-induced mitochondrial depolarization and selective elimination of cancer cells in vivo. Moreover, the therapeutic efficacy of the gene therapy in metastatic a model is essential because most diagnosed NE cancer patients are metastatic. The specific objective of this application is to develop, produce and evaluate an innovative NE cancer-targeted mitochondrial gene therapy to selectively destroy and eliminate NETs in vivo. The following two specific aims over a 12-month period are propose. Aim 1: To develop, produce and characterize the NE-cancer targeted mitochondrial gene therapy. A high-quality anti-SSTR2 mAb-Exo-AAV will be constructed by cloning a cancer promoter (cfos) and the fused blue light- producing luciferase and light-gated rhodopsin gene, i.e. cfos-NLuc-2A-ABCB-CoChR (~3.3 kb), into the engineered pAAV-MCS promoterless expression vector, and produced using our stirred-tank bioreactor-based exosome-AAV biomanufacturing platform and surface tagging technology. The anti-SSTR2 mAb-Exo-AAV will then be evaluated for its cancer specific targeting and in vitro anti-cancer efficacy. Aim 2: To evaluate the therapeutic values of the mitochondrial gene therapy using preclinical NET metastatic animal model. Most NE cancer patients are initially diagnosed with metastases and have already developed carcinoid syndrome. Therefore we will evaluate the maximal tolerated dose (MTD), pharmacokinetics (PK), anti- NET efficacy, and liver metastases reduction of the developed gene therapy using metastatic model.PROJECT NARRATIVE Neuroendocrine (NE) cancers are neuroendocrine neoplasms with widespread hepatic metastases, and there is no effective biotherapy currently. In this project, an innovative mitochondrial chemo-optogenetics gene therapy, delivered via our NE cancers-targeting monoclonal antibody tagged exosome-associated adeno-associated virus (mAb-Exo-AAV), will be developed, produced and evaluated. This targeted therapy could improve the life quality and survival rate of NE cancer patients.