Metastatic tumor cells detection and anti-metastatic potential with vesicular stomatitis virus in immunocompetent murine model of osteosarcoma

Oncolytic Viral Therapy in Osteosarcoma

Primary bone malignancies, including osteosarcoma (OS), are rare but aggressive. Current OS treatment, involving surgical resection and chemotherapy, has improved survival for non-metastatic cases but remains ineffective for recurrent or metastatic OS. Oncolytic viral therapy (OVT) is a promising alternative, using naturally occurring or genetically modified viruses to selectively target and lyse cancer cells and induce a robust immune response against remaining OS cells. Various oncolytic viruses (OVs), such as adenovirus, herpes simplex virus, and measles virus, have demonstrated efficacy in preclinical OS models. Combining OVT with other therapeutics, such as chemotherapy or immunotherapy, may further improve outcomes. Despite these advances, challenges in reliability of preclinical models, safety, delivery, and immune response must be addressed to optimize OVT for clinical use. Future research should focus on refining delivery methods, exploring combination treatments, and clinical trials to ensure OVT's efficacy and safety for OS. Overall, OVT represents a novel approach with the potential to drastically improve survival outcomes for patients with OS.

Surgical Treatment of Osteosarcoma Induced Distant Pre-Metastatic Niche in Lung to Facilitate the Colonization of Circulating Tumor Cells

Recently, the major challenge in treating osteosarcoma patients is the metastatic disease, most commonly in the lungs. However, the underlying mechanism of recurrence and metastasis of osteosarcoma after surgical resection of primary tumor remains unclear. This study aims to investigate whether the pulmonary metastases characteristic of osteosarcoma is associated with surgical treatment and whether surgery contributes to the formation of pre-metastatic niche in the distant lung tissue. In the current study, the authors observe the presence of circulating tumor cells in patients undergoing surgical resection of osteosarcoma which is correlated to tumor recurrence. The pulmonary infiltrations of neutrophils and Gr-1+ myeloid cells are characterized to form a pre-metastatic niche upon the exposure of circulating tumor cells after surgical resection. It is found that mitochondrial damage-associated molecular patterns released from surgical resection contribute to the formation of pre-metastatic niche in lung through IL-1β secretion. This study reveals that surgical management for osteosarcoma, irrespective of the primary tumor, might promote the formation of postoperative pre-metastatic niche in lung which is with important implications for developing rational therapies during peri-operative period.

Oncolytic Viruses and Their Potential as a Therapeutic Opportunity in Osteosarcoma

Osteosarcoma remains an unmet medical need. Oncolytic viruses are gaining traction as novel cancer therapeutics. These viruses are either naturally nonpathogenic or engineered to be safe by specific genetic deletions yet retain the ability to infect and kill human cancer cells and elicit anticancer immunity. Some versions are being specifically designed and tested in patients with osteosarcoma, though due to their generalized mechanism of action most are being tested in patients across a broad range of cancer types. The activity of these viruses is impacted not only by the susceptibility of tumor cells to infection but also by the tumor microenvironment (TME) and by tumor immunogenicity. Here we review the field of oncolytic viruses with a particular emphasis on highlighting any available data in preclinical osteosarcoma models or in patients with osteosarcoma. While in general the viruses have been shown safe to administer to patients by a variety of routes, their therapeutic efficacy to date has been limited. Given the low rate of adverse events and the likely absence of long-term side effects, the utility of oncolytic viruses will most likely be realized when used in combination with other agents.

Novel Near-Infrared Fluorescence-Guided Surgery With Vesicular Stomatitis Virus for Complete Surgical Resection of Osteosarcomas in Mice

Attempts have been made to visualize tumor cells intraoperatively with fluorescence guidance. However, the clear demarcation and complete tumor resection have always been a challenging task. To address this, we have developed a novel fluorescence bioimaging system with vesicular stomatitis virus (VSV) incorporating Katushka, near-infrared fluorescent protein. VSV is tumor-specific owing to the deficiency of antiviral interferon signaling pathways in tumor cells. We aimed to evaluate the tumor specificity of the recombinant VSV-Katushka (rVSV-K) in osteosarcoma cells and to assess the feasibility of complete tumor resection by the rVSV-K fluorescence guidance. In in vitro experiments, mouse and human osteosarcoma cell lines and normal human mesenchymal stem cells were infected with rVSV-K and observed by fluorescence microscopy. Near-infrared fluorescence was observed only in osteosarcoma cells, even at a low-concentration of virus infections. In in vivo experiments, mouse osteosarcoma (LM8) cells were transplanted subcutaneously into the back of immune-competent mice to produce an osteosarcoma, which was then injected with rVSV-K. The areas emitting fluorescence were resected using a bioimaging system. The distance between the surgical and tumor margins of the fluorescence-guided resection with rVSV-K group was significantly larger than that of the non-guided resection groups. The local recurrence rate was significantly lower in the fluorescence-guided resection with rVSV-K group than in the non-guided resection groups. The distant metastasis rate and average survival rate were not significantly different between all groups. These results suggest that the rVSV-K is specific to osteosarcoma cells and enables complete tumor resection of osteosarcomas in mice. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.