Abstract 2981: Combination therapy of oncolytic herpes virus HF10 and bevacizumab against experimental model of human breast carcinoma xenograft

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Abstract Background: Breast cancer is one of the most common and feared cancers in women. Multimodal therapy with a more specific and effective strategy is urgently needed. Oncolytic HSV is a good candidate because of broad host range and tumor selective viral distribution. In our study, the combination effect of oncolytic herpes virus HF10 and Bevacizumab in the treatment of experimental model of human breast carcinoma xenograft is evaluated. Method: The VEGFA gene transcription and protein expression was measured in three human breast cancer cell lines (MCF-7,T47D and MDA-MB-231) by RT-PCR, Western blot and ELISA. The MTT analysis was performed to evaluate the efficiency of combination therapy in vitro. The effect on viral replication was evaluated by PCR and titering of the virus replicating under various doses of Bevacizumab. The advanced tumor model was formed by 12 female BALB/c nude mice which were implanted 4 pieces of 5 mm x 5mm MDA-MB-231 tumor to the flank site. The single tumor model was made by 28 female BALB/c nude mice which were implanted 1 piece of 5 mm x 5mm MDA-MB-231 tumor to the right flank site. Control group received no treatment. The HF10 group of advanced tumor model received two single injections of 10^6 pfu/dose intratumorally on Day 1 and Day 14. The HF10 group of single tumor model received one single injection of 10^6 pfu/dose intratumorally on Day 1. Bevacizumab group received 5mg/kg Bevacizumab intra-peritoneally twice a week for 2 weeks. Combination group received both intratumoral HF10 and intraperitoneally Bevacizumab at the same dose. The tumor diameter was measured weekly. On Day 2 and Day 35 following the last dose of the treatment tumors were collected. Histopathological parameters were HIF1A, VEGFA, Thrombospondin 1, CD31 driven microvascular density, CD4, CD8, Caspase 3, Cyr61 and HSV-1 antigen. Results: Among the three candidate cell lines, MDA-MB-231 has the highest level of VEGFA expression, while T47D has the lowest level of VEGFA expression. The cytotoxic effect of HF10 is time- and dose- dependent in vitro. Combination therapy does not affect viral replication in vitro. In the in vivo study, combination group had the smallest tumor volume comparing with other groups in both animal models (P<0.05). Combination therapy induced synergistic effect in vivo in both animal models. Viral distribution was significantly enhanced in the combination group when compared to HF10 group on both Day 2 and Day 35. Conclusion: Enhanced angiogenesis effect following viral treatment remains as an obstacle of oncolytic viral therapy. Anti-angiogenesis reagent is effective to achieve better antitumor effect. Our result shows that Bevacizumab enhances the viral distribution by antagonizing vascular permeability and decreasing tumor interstitial pressure and therefore promotes the oncolytic effect. It can be a promising virus-associated agent in the anticancer treatment. Citation Format: Gewen Tan, Hideki Kasuya, Tevfik Tolga Sahin, Toshio Shikano, Suguru Yamada, Akiyuki Kanzaki, Kazuo Yamamura, Tsutomu Fujii, Hiro-yuki Sugimoto, Shuji Nomoto, Yoko Nishikawa, Maki Tanaka, Naoko Tsurumaru, Shin Takeda, Akimasa Nakao, Yasuhiro Kodera. Combination therapy of oncolytic herpes virus HF10 and bevacizumab against experimental model of human breast carcinoma xenograft. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2981. doi:10.1158/1538-7445.AM2014-2981