Used in targeted radionuclide therapy for metastatic castration-resistant prostate cancer. Binds to prostate-specific membrane antigen (PSMA) highly expressed on prostate cancer cells. When labeled with therapeutic radionuclides like lutetium-177, delivers radiation directly to tumor cells while sparing healthy tissue. Enables both imaging and treatment, supporting theranostic approaches. Improves progression-free survival and symptom control in eligible patients. Also under investigation for use with other radionuclides and in earlier stages of prostate cancer.