Current efforts on expanding minimally invasive techniques into the realm of oncological surgery are hindered by lack of accurate visualization of tumor margins and failure to detect micro metastases in real time. We used a systemic delivery of a herpes viral vector with cancer-selective infection and replication to precisely differentiate between normal and malignant tissue. NV1066 is a genetically modified, replication-competent herpes simplex virus carrying a transgene for enhanced green fluorescent protein (GFP). We tested the potential of NV1066 in delineating tumor tissue in vitro and in vivo in a wide range of cancers and whether NV1066-induced GFP expression can detect small foci of tumors and metastases in in vivo models using an operating endoscope with fluorescent filters. Our findings indicate that NV1066 can be used for real-time intraoperative imaging and enhanced detection of early cancers and metastases. We demonstrate that a single dose of NV1066, administered either locally (intratumoral or intracavitary) or systemically, will detect loco-regional and distant disease throughout the body. Such cancer selectivity is confirmed in 110 types of cancer cells from 16 different primary organs. Fluorescence-aided minimally invasive endoscopy revealed microscopic tumor deposits unrecognized by conventional laparoscopy/thoracoscopy. Furthermore, NV1066 ability to transit and infect tumor and metastases is proven in syngenic and transplanted tumors in different animal models, both immunocompetent and immunodeficient. Cancer-selective GFP expression is confirmed by histology, immunohistochemistry, and qRT-PCR. These studies form the basis for real-time, intraoperative diagnostic imaging of tumor and metastases by minimally invasive endoscopic technology.

Key words: oncolytic viral therapy • gene therapy • HSV • endoscopy