In our current study we have therefore tested 2 orally available, potent and selective, clinically tested, ATM inhibitors (ATMi)—AZD0156 and its analog AZD1390—on their ability to increase the efficacy of Ra-223 in a BALB/c nude mouse model of human prostate cancer bone metastasis in addition to an immune-competent C57BL/6 model of prostate cancer bone metastasis. The gene discussed is ATM; the disease is prostate cancer.