Theranostic methods are changing the standard of care in men with prostate cancer. By enabling targeted imaging and therapy, agents targeting prostate-specific membrane antigen (PSMA) enable both detection and subsequent treatment of recurrent or metastatic prostate cancer. However, a significant fraction of prostate tumors demonstrates heterogeneous, low, or absent expression of PSMA. CD46 is a cell surface antigen that is highly expressed on the surface of prostate cancer cells including those that are PSMA negative.