The tumor microenvironment is a relevant target for novel biological therapies. While it has been demonstrated that tumor-stromal cell interactions are important in the sensitivity of the cancer cells to oncolytic virues, few studies have investigated the direct effects of an oncolytic virus on the stroma, and its implications on the virus antitumor efficacy.

MV-m-uPA and MV-h-uPA are fully retargeted, species specific, oncolytic measles viruses directed against murine or human urokinase receptor (uPAR). The effects of stromal selective targeting by uPAR retargeted MVs were investigated. In vitro infection, gene expression and cytotoxicity by MV-h-uPA and MV-m-uPA were demonstrated in human and murine cancer cells and cancer associated fibroblasts in a species specific manner. In murine fibroblast (3T3)/human breast cancer (T47D) 3-D co-cultures, selective fibroblast targeting by MV-m-uPA inhibited breast cancer cell growth.  These effects were validated in vivo, in a human breast cancer xenograft (MDA-MB-231), where intravenous administration of the murine specific MV-m-uPA led to significant tumor growth delay and improved survival compared to controls. Experiments comparing the effects of tumor (MV-h-uPA) vs. stromal (MV-m-uPA) vs. combined treatment showed that tumor and stromal targeting was associated with improved tumor control. Correlative studies demonstrated in vivo tumor targeting, increased apoptosis, and MV-m-uPA induced differential regulation of both stromal (murine) genes and cancer (human) genes associated with inflammation, angiogenesis and survival, among others, indicating viral induced modulation of tumor-stromal interactions.

Our results demonstrate for the first time the feasibility of stromal selective targeting by an oncolytic MV, viral induced modulation of the tumor microenvironment, and subsequent tumor growth delay. These findings further validate the critical role of stromal uPAR in cancer progression and the potential of oncolytic viruses as anti-stromal agents.

Citation Format: Yuqi Jing, Valery Chavez, Nicolas Acquavella, Doraya El-Ashry, Yuguang Ban, Xi Chen, Jaime Merchan. In vitro, in vivo and molecular effects of stromal selective targeting by uPAR retargeted oncoytic measles virus on breast cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5093. doi:10.1158/1538-7445.AM2017-5093