Title: Tumor-targeting adenovirus OBP-401 inhibits primary and metastatic tumor growth of triple-negative breast cancer in orthotopic nude-mouse models
Abstract: // Shuya Yano 1, 2, 3 , Kiyoto Takehara 1, 2, 3 , Hiroyuki Kishimoto 3 , Hiroshi Tazawa 4 , Yasuo Urata 5 , Shunsuke Kagawa 3 , Michael Bouvet 2 , Toshiyoshi Fujiwara 3 , Robert M. Hoffman 1, 2 1 AntiCancer, Inc., San Diego, CA, USA 2 Department of Surgery, University of California San Diego, CA, USA 3 Department of Gastroenterological Surgery, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan 4 Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan 5 Oncolys BioPharm Inc., Tokyo, Japan Correspondence to: Robert M. Hoffman, email: [email protected] Toshiyoshi Fujiwara, email: [email protected] Keywords : triple-negative breast cancer, TNBC, high-metastatic, variants, nude mouse, adenovirus, OBP-401 Abbreviations : GFP, green fluorescent protein; RFP, red fluorescent protein. Received: September 27, 2016 Accepted: October 24, 2016 Published: November 11, 2016 ABSTRACT Our laboratory previously developed a highly-invasive, triple-negative breast cancer (TNBC) variant using serial orthotopic implantation of the human MDA-MB-231 cell line in nude mice. The isolated variant was highly-invasive in the mammary gland and lymphatic channels and metastasized to lymph nodes in 10 of 12 mice compared to 2 of 12 of the parental cell line. In the present study, the tumor-selective telomerase dependent OBP-401 adenovirus was injected intratumorally (i.t.) (1 × 10 8 PFU) when the high-metastatic MDA-MB-231 primary tumor expressing red fluorescent protein (MDA-MB-231-RFP) reached approximately 500 mm 3 (diameter; 10 mm). The mock-infected orthotopic primary tumor grew rapidly. After i.t. OBP-401 injection, the growth of the orthotopic tumors was arrested. Six weeks after implantation, the fluorescent area and fluorescence intensity showed no increase from the beginning of treatment. OBP-401 was then injected into high-metastatic MDA-MB-231-RFP primary orthotopic tumor growing in mice which already had developed metastasis within lymphatic ducts. All 7 of 7 control mice subsequently developed lymph node metastasis. In contrast, none of 7 mice which received OBP-401 had lymph node metastasis. Seven of 7 control mice also had gross lung metastasis. In contrast, none of the 7 mice which received OBP-401 had gross lung metastasis. Confocal laser microscopy imaging demonstrated that all control mice had diffuse lung metastases. In contrast, all 7 mice which received OBP-401 only had a few metastatic cells in the lung. OBP-401 treatment significantly extended survival of the treated mice.