Current status of radioligand therapy and positron-emission tomography with prostate-specific membrane antigen

Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein highly expressed by prostate cancer cells. PSMA-based radioligand therapy (RLT) emerged as a promising therapeutic option for prostate cancer in the early 2000s, and has been clinically validated with great enthusiasm during these past two decades. Last year, the European Association of Nuclear Medicine (EANM) published the procedure guidelines for the safe clinical practice of Lutetium-177 (¹⁷⁷Lu)-labelled PSMA RLT. In addition, PSMA RLT with alpha-ray-emitting radioisotopes has been also developed recently. Following the clinical use of ¹⁷⁷Lu-PSMA RLT, PSMA-targeted positron-emission tomography (PET) with Gallium-68 (⁶⁸Ga) has been performed inevitably for "theranostics" for the last decade; prostate cancer is going to be treated with PSMA-RLT based on the diagnosis by PSMA-PET. Furthermore, the diagnostic usefulness of ⁶⁸Ga-PSMA PET has been documented in various diseases beyond prostate cancer more recently. Regrettably, Japan is behind European countries and the United States in this field, and has just made a belated start of their clinical trials. In this review article, we briefly overviewed the current status of PSMA RLT and PSMA PET. We hope that this topic will be a particular focus of attention for most ANM readers in Japan, and that our efforts will help to facilitate the early approval of PSMA RLT and PSMA PET by the Japanese government even if only slightly.