Despite the proven safety of oncolytic viruses (OV) in clinical trials for glioblastoma (GBM), their efficacy has been hindered by suboptimal spreading within the tumor. We show that hyaluronan or hyaluronic acid (HA), an important component of extracellular matrix (ECM), is highly expressed in a majority of tumor xenografts established from patient-derived GBM lines that present both invasive and nodular phenotypes. Intratumoral injection of a conditionally replicating adenovirus expressing soluble hyaluronidase (ICOVIR17) into nodular GBM, mediated HA degradation and enhanced viral spread, resulting in a significant antitumor effect and mice survival. In an effort to translate OV-based therapeutics into clinical settings, we encapsulated human adipose-derived mesenchymal stem cells (MSC) loaded with ICOVIR17 in biocompatible synthetic extracellular matrix (sECM) and tested their efficacy in a clinically relevant mouse model of GBM resection. Compared with direct injection of ICOVIR17, sECM-MSC loaded with ICOVIR17 resulted in a significant decrease in tumor regrowth and increased mice survival. This is the first report of its kind revealing the expression of HA in GBM and the role of OV-mediated HA targeting in clinically relevant mouse model of GBM resection and thus has clinical implications.
Treatment of metastatic tumors with engineered adenoviruses that replicate selectively in tumor cells is a new therapeutic approach in cancer. Systemic administration of these oncolytic adenoviruses lack metastatic targeting ability. The tumor stroma engrafting property of intravenously injected mesenchymal stem cells (MSCs) may allow the use of MSCs as cellular vehicles for targeted delivery. In this work, we study the safety and the efficacy of infusing autologous MSCs infected with ICOVIR-5, a new oncolytic adenovirus, for treating metastatic neuroblastoma. Four children with metastatic neuroblastoma refractory to front-line therapies received several doses of autologous MSCs carrying ICOVIR-5, under an approved preliminary study. The tolerance to the treatment was excellent. A complete clinical response was documented in one case, and the child is in complete remission 3 years after this therapy. We postulate that MSCs can deliver oncolytic adenoviruses to metastatic tumors with very low systemic toxicity and with beneficial antitumor effects.
Human MSC loaded with different oHSV variants provide a platform to translate oncolytic virus therapies to clinics in a broad spectrum of GBMs after resection and could also have direct implications in different cancer types.
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