Extent of radiosensitization by the PARP inhibitor olaparib depends on its dose, the radiation dose and the integrity of the homologous recombination pathway of tumor cells.

Background And Purpose: The PARP inhibitor olaparib is currently tested in clinical phase 1 trials to define safe dose levels in combination with RT. However, certain clinically relevant insights are still lacking. Here we test, while comparing to single agent activity, the olaparib dose and genetic background dependence of olaparib-mediated radiosensitization.