Recently, CD46 has emerged as a promising target for the treatment of both adenocarcinoma and neuroendocrine types of metastatic castration-resistant prostate cancer (mCRPC). YS5, a human full-length IgG1 with high specificity for CD46, was identified to have high binding affinity for prostate cancer tissue. YS5 has been developed into an antibody-drug conjugate, FOR46, which is currently in a phase I clinical trial (NCT03575819) for the treatment of mCRPC. Since then, a companion molecular imaging agent for CD46-targeted therapy has been developed.