BACKGROUND AND PURPOSE: Esophageal cancer has a persistently low 5-year survival rate and has recently been classified as a cancer of unmet need by Cancer Research UK. Consequently, new approaches to therapy are urgently required. Here, we tested the hypothesis that an ATR inhibitor, VX-970, used in combination with standard therapies for esophageal cancer could improve treatment outcome. MATERIAL AND METHODS: Using esophageal cancer cell lines we evaluated the efficacy of combining VX-970 with cisplatin and carboplatin in vitro and with radiation in vitro and in vivo. Radiation experiments were also carried out in hypoxic conditions to mimic the tumor microenvironment. RESULTS: Combining VX-970 with cisplatin, carboplatin and radiation increased tumor cell kill in vitro. A significant tumor growth delay was observed when VX-970 was combined with radiotherapy in vivo. CONCLUSIONS: VX-970 is an effective chemo/radiosensitizer which could be readily integrated in the current treatment paradigm to improve the treatment response in esophageal cancer and we plan to test it prospectively in the forthcoming phase I dose escalation safety study combining the ATR inhibitor VX-970 with chemoradiotherapy in esophageal cancer (EudraCT number: 2015-003965-27).
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ATR, Esophageal cancer, Hypoxia, Radiation, Animals, Antineoplastic Combined Chemotherapy Protocols, Ataxia Telangiectasia Mutated Proteins, Cell Line, Tumor, Chemoradiotherapy, Esophageal Neoplasms, Humans, Isoxazoles, Mice, Pyrazines