Preclinical testing of an ATR inhibitor demonstrates improved response to standard therapies for esophageal cancer

Abstract 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).