Minimally invasive localization of oncolytic herpes simplex viral therapy of metastatic pleural cancer

Abstract

Purpose-Herpes simplex virus-one (HSV-1) oncolytic therapy and gene therapy are promising treatment modalities against cancer. NV1066, one such HSV-1 virus carries a marker gene for enhanced green fluorescent protein (EGFP). The purpose of this study was to determine whether NV1066 is cytotoxic to lung cancer and whether EGFP is a detectable marker of viral infection in vitro and in vivo. We further investigated whether EGFP expression in infected cells can be used to localize the virus and to identify small metastatic tumor foci (< 1 mm.) in vivo by means of minimally invasive endoscopic systems equipped with fluorescent filters.Experimental Design-In A549 human lung cancer cells, in vitro viral replication was determined by plaque assay, cell kill by LDH release assay, and EGFP expression by flow cytometry. In vivo, A549 cells were injected into the pleural cavity of athymic mice. Mice were treated with intrapleural injection of NV1066 or saline and examined for EGFP expression in tumor deposits using a stereomicroscope or a fluorescent thoracoscopic system. Results-NV1066 replicated in, expressed EGFP in infected cells and killed tumor cells in vitro.In vivo, treatment with intrapleural NV1066 decreased pleural disease burden, as measured by chest wall nodule counts and organ weights. EGFP was easily visualized in tumor deposits, including microscopic foci, by fluorescent thoracoscopy.Conclusions-NV1066 has significant oncolytic activity against a human NSCLC cell line and is effective in limiting the progression of metastatic disease in an in vivo orthotopic model. By incorporating fluorescent filters into endoscopic systems, a minimally-invasive means for diagnosing small metastatic pleural deposits and localization of viral therapy for thoracic malignancies may be developed using the EGFP marker gene inserted in oncolytic herpes simplex viruses.

Fluorescence-guided Surgery with a Fluorophore-conjugated Antibody to Carcinoembryonic Antigen (CEA), that Highlights the Tumor, Improves Surgical Resection and Increases Survival in Orthotopic Mouse Models of Human Pancreatic Cancer

“…23,24 Other examples include the use of replication-competent adenovirus engineered to express GFP in the presence of activated telomerase or by targeting rapidly replicating cells with the oncolytic herpes simplex-1 virus, NV1066. 25–28 Furthermore, there has been interest in using fluorophore-conjugated antibodies to unique surface markers expressed by individual tumor types. 12,14, 29,30 These methods have all shown promising capabilities to label tumor for enhanced detection and subsequent resection under fluorescence-guidance, leading to improved DFS and OS in mouse models of cancer.…”

Regional Liver Therapy Using Oncolytic Virus to Target Hepatic Colorectal Metastases

“…For example, carotid perfusion of oHSV cured experimental oral cancer in a hamster model (59), while single doses of oHSV via peritoneal and pleural perfusion in murine models have shown both tumor regression and cure in experimental animals with disseminated xenografts of human gastric cancer, colorectal cancer, esophageal cancer, and mesothelioma (60–64). Accordingly, a wealth of preclinical data have been reported by several groups showing efficacy of oncolytic viral therapy against colorectal cancer and hepatic colorectal metastases in models of both local and systemic therapy (Table 1).…”

Current status and future perspectives of fluorescence-guided surgery for cancer

“…The virus was injected directly into primary tumors and was able to locate and replicate within metastatic lymph nodes that were then visualized with fluorescence imaging [44]. This technique also has the potential to be used as a highly sensitive diagnostic for cancer.…”