177Lu

177Lu (lutetium-177) is a radionuclide used in targeted radionuclide therapy (TRNT). It decays by beta-minus emission to hafnium-177 with a half-life of 6.647 days. In addition to beta radiation, it emits gamma rays at 113 keV and 208 keV, enabling imaging and dosimetry with conventional gamma cameras or SPECT. The beta radiation provides a therapeutic dose to targeted cells within a few millimeters of the emission, making it suitable for treating small to medium-sized tumors and metastases while limiting damage to surrounding tissue.

Production of 177Lu occurs primarily in nuclear reactors. It is produced by neutron irradiation of lutetium-176 targets (direct route) or via indirect routes involving ytterbium isotopes. Production quality aims at high specific activity and chemical purity to support radiopharmaceutical kit formulation.

Medical use of 177Lu is centered on peptide receptor radionuclide therapy (PRRT). The most widely known therapy is 177Lu-DOTATATE (Lutathera) for somatostatin receptor–positive neuroendocrine tumors, approved in many regions. Another radiopharmaceutical, 177Lu-PSMA-617, is used for metastatic castration-resistant prostate cancer, with regulatory approvals in several jurisdictions. Treatments are given intravenously in cycles, often with nephroprotection, and include post-therapy imaging for response assessment.

Safety and regulation: Like other radiopharmaceuticals, 177Lu therapies require specialized facilities, trained personnel, and adherence to radiation safety. Potential adverse effects include hematologic toxicity and renal toxicity, necessitating careful patient selection and dosimetry.

Status: 177Lu continues to be investigated in various indications and dosimetry methods, with ongoing efforts to optimize dosing, imaging, and combination therapies.