Nuklearmedizinische Theranostik: Update Nuklearmedizin 2021

Background: Theranostic approaches increasingly define the combined diagnostic and therapeutic patient management in nuclear medicine. Three novel approaches in different clinical stages are presented. Methods: The manuscript is based on a literature and guideline compilation on the current status of selected radiopharmaceuticals. Results: For prostate cancer, radiolabeled ligands to prostate-specific membrane antigen (PSMA) have been available for several years. ⁶⁸Ga-PSMA PET/CT is currently used under the rules of „Ambulante Spezialärztliche Versorgung“ (ASV) for diagnosis of early biochemical recurrences. Recent studies also demonstrate clear advantages in the initial staging of high-risk patients. For therapy of metastatic castration-resistant prostate cancer (mCRPC), ¹⁷⁷Lu-PSMA is available and can be used in accordance with the current German S3 guideline. Moreover, a phase III study was recently reported to meet the primary endpoints indicating an early drug approval. The chemokine receptor 4 (CXCR4) ligands ⁶⁸Ga-pentixafor and ⁹⁰Y/¹⁷⁷Lu-pentixather provide a pair of theranostics for the receptor-specific detection and therapy of tumors expressing chemokine receptor 4. Results of first clinical studies in hematological neoplasms such as non-Hodgkin’s lymphoma, CNS lymphoma and multiple myeloma suggest an increased use of these radiopharmaceuticals in the future. Radiolabeled inhibitors against fibroblast activation protein (FAP) are currently opening completely new diagnostic and therapeutic aspects in tumors with a high stromal proportion and immune involvement, such as colon, pancreatic, and ovarian cancer. Although data are still limited, the central role of FAP-positive tumor fibroblasts in neoangiogenesis and immune response suggests significant contributions to in vivo image-based phenotyping and combined tumor therapy. Conclusion: Following the approval of Lutathera® (Lutetium[177Lu]-Oxodotreotid), three new theranostic approaches for the systemic treatment of tumors are currently under clinical investigation, with PSMA ligands for diagnosis and treatment of prostate cancer already having found their way into the current S3 guideline.