SHR-1701 in Combination With Stereotactic Body Radiotherapy in mCRPC

This study tests whether combining an immunotherapy drug (SHR-1701, which blocks a protein that helps cancer hide from the immune system) with targeted radiation therapy (SBRT—high-dose radiation aimed precisely at a small number of tumors) can help men with advanced prostate cancer that has stopped responding to hormone treatments. **You may be eligible if...** - You are between 18 and 80 years old and have confirmed advanced prostate cancer - Your cancer has stopped responding to at least one type of hormone-blocking drug - You have also received docetaxel chemotherapy or have a documented reason you cannot - Your testosterone levels are maintained at very low (castrate) levels - You have adequate blood counts, liver, kidney, and heart function **You may NOT be eligible if...** - You have cancer that has spread to the brain - You have received immunotherapy (checkpoint inhibitors) before - You have an active autoimmune disease requiring systemic treatment - You have significant neurological or psychiatric disorders - You have had recent radiation therapy or certain hormone treatments Talk to your doctor to see if this trial is right for you.