(UroToday.com) Since 2015, several phase 3 randomized controlled trials have demonstrated that adding either androgen pathway inhibitors or chemotherapy to testosterone suppression can prolong overall survival for men diagnosed with metastatic hormone-sensitive metastatic prostate cancer (mHSPC). The STAMPEDE study has specifically demonstrated a survival advantage in mHSPC with the addition of the androgen synthesis inhibitor abiraterone acetate. Based on observations from STAMPEDE that radiation therapy may reduce treatment failure rates in locally advanced prostate cancers as well as preclinical data suggesting that stereotactic body radiotherapy (SBRT) can induce expression of PD-L1 on tumor and immune cells, the authors of this abstract tested the hypothesis that the combination of testosterone suppression, abiraterone acetate, SBRT and the anti-PD-L1 drug atezolizumab may together exert synergistic effects to improve outcomes in men with mHSPC.