Abstract 2873: Elimination of MYCN-amplified neuroblastoma cells by telomerase-targeted oncolytic virotherapy as novel precision medicine
Authors: Tani Morimichi , Tazawa Hiroshi , Tanimoto Terutaka , Nouso Hiroshi , Urata Yasuo , Kagawa Shunsuke , Noda Takuo , Fujiwara Toshiyoshi 
Published: August 2019

Abstract
Background: Neuroblastoma (NB) is a primary malignant tumor of the peripheral sympathetic nervous system. Recent whole-genome sequencing studies have demonstrated that high-risk NB with unfavorable clinical outcome is characterized by amplification of MYCN oncogene and rearrangement of human telomerase reverse transcriptase (hTERT) gene. Since hTERT expression is transcriptionally and commonly activated in high-risk NB, hTERT activation would be an attractive therapeutic target for the treatment of high-risk NB. To eliminate hTERT-activated malignant tumor cells, we have developed two types of hTERT-driven oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702. In this study, we investigated the therapeutic potential of hTERT-driven oncolytic adenoviruses OBP-301 and OBP-702 in MYCN-amplified NB cells.
Methods: We used 4 human NB cell lines with MYCN amplification (IMR-32, CHP-134, NB-1, LA-N-5). The expression of cell surface coxsackie and adenovirus receptor (CAR) and hTERT was analyzed using flow cytometric analysis and real-time RT-PCR. We assessed the in vitro antitumor effect of OBP-301 and OBP-702 using a XTT assay. The molecular mechanism of virus-mediated antitumor effect was investigated in aspect of apoptosis, autophagy, and MYCN expression. To address the underlying mechanism of virus-mediated MYCN modulation, we analyzed the role of E2F1 and p53 in the virus-infected NB cells. The in vivo antitumor effect of OBP-301 and OBP-702 was assessed using a subcutaneous CHP-134 xenograft tumor model.
Results: All MYCN-amplified NB cells showed CAR and hTERT expression. OBP-301 and OBP-702 showed profound antitumor effect in association with autophagy-related cell death in all MYCN-amplified NB cells. In the virus-infected NB cells, E2F1 expression was inversely correlated with MYCN expression. Virus-induced E2F1 and p53 expression suppressed the MYCN expression in the MYCN-amplified NB cells. OBP-301 and OBP-702 significantly suppressed tumor growth in a subcutaneous CHP-134 xenograft tumor model.
Conclusion: Our results suggest that hTERT-driven oncolytic adenoviruses OBP-301 and OBP-702 are promising antitumor agents for eliminating the MYCN-amplified NB cells through E2F1- and p53-mediated suppression of oncogenic MYCN protein. Further clinical study is warranted to evaluate the safety and feasibility of hTERT-driven oncolytic virotherapy as novel precision medicine for high-risk NB patients.
Citation Format: Morimichi Tani, Hiroshi Tazawa, Terutaka Tanimoto, Hiroshi Nouso, Yasuo Urata, Shunsuke Kagawa, Takuo Noda, Toshiyoshi Fujiwara. Elimination of MYCN-amplified neuroblastoma cells by telomerase-targeted oncolytic virotherapy as novel precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2873.