Guide to Radiopharmaceuticals Used in Theranostics

Theranostics connects diagnosis and treatment through targeted radiopharmaceuticals. A diagnostic agent can identify whether a particular molecular target is present, while a related therapeutic agent can deliver radiation to cells carrying that target. The International Atomic Energy Agency describes gallium 68 and lutetium 177 as an important diagnostic and therapeutic pair used in modern theranostics.

Understanding Common Theranostic Radiopharmaceuticals

Radiopharmaceuticals generally contain a radioactive isotope and a targeting molecule. The targeting component guides the radiopharmaceutical toward a particular receptor, protein, or biological pathway, while the radionuclide provides either imaging signals or therapeutic radiation.

Common examples include:

• Gallium 68: A positron emitting radionuclide commonly used with targeted molecules for PET imaging. Gallium 68 labeled agents can help demonstrate whether specific tumor targets are present before radionuclide therapy.
• Lutetium 177: A therapeutic radionuclide that emits beta radiation and can deliver treatment to targeted cells. Lutetium 177 dotatate targets somatostatin receptors and is used for certain somatostatin receptor positive gastroenteropancreatic neuroendocrine tumors.
• Lutetium 177 vipivotide tetraxetan: This targeted radiopharmaceutical binds to PSMA, a protein expressed on many prostate cancer cells. Its use includes selected patients with PSMA positive metastatic prostate cancer.
• Iodine 123 and iodine 131: These isotopes represent an established theranostic concept, with iodine 123 used for diagnostic imaging and iodine 131 providing therapeutic radiation in appropriate thyroid-related applications.

How Theranostic Radiopharmaceuticals Support Treatment

The theranostic process usually begins with molecular imaging. A patient receives a diagnostic radiopharmaceutical, followed by imaging such as PET or another nuclear medicine scan. The resulting images can show whether the intended biological target is present and where it is distributed.

Important aspects include:

• Target identification: Imaging can help determine whether tumors express the molecular target required for a particular therapy.
• Treatment selection: Demonstrating target expression may help clinicians identify patients who could be appropriate candidates for targeted radionuclide therapy.
• Targeted radiation delivery: Therapeutic radionuclides release radiation near or within targeted cells, with the aim of damaging their DNA.
• Treatment monitoring: Follow-up imaging and clinical assessments can help evaluate disease response and guide ongoing management.
• Personalized care: Matching the treatment to a demonstrated molecular target is an important feature of precision nuclear medicine.

Theranostic radiopharmaceuticals are administered and monitored by specialized healthcare teams because radioactive medicines require appropriate preparation, handling, dosimetry, radiation protection, and patient monitoring. Treatment suitability depends on factors such as the disease type, molecular target, previous treatments, organ function, and individual clinical circumstances.

Overall, radiopharmaceutical theranostics represents an important development in nuclear medicine by connecting molecular imaging with targeted radionuclide treatment. Established approaches involving iodine, gallium 68, and lutetium 177 demonstrate how diagnostic information can support treatment selection and personalized management. Research continues to investigate additional radionuclides, targeting molecules, and combinations that may expand the role of theranostics across cancer care and other diseases.