Radiopharmaceuticals in Cancer Treatment

Introduction to Radiopharmaceuticals

• Radiopharmaceuticals, such as alpha particle radiopharmaceuticals, can be effective as a sequential treatment option following Lutetium-177 (LU-177) infusions in patients with progressive disease, particularly when there is high uptake on diagnostic imaging and adequate bone marrow reserve, as recommended by the European Society for Medical Oncology 1

Patient Selection and Treatment Algorithm

• Optimal candidates for alpha particle radiopharmaceuticals after LU-177 therapy should demonstrate superior radiopharmaceutical uptake at all tumor sites on diagnostic imaging, have reasonable bone marrow reserve, adequate renal function, and be in a self-caring status to minimize radiation exposure risk to healthcare staff, as recommended by the European Society for Medical Oncology 1
• Patients with neuroendocrine tumors (NETs) who have disease progression on somatostatin analogs (SSAs) and meet the general requirements for Peptide Receptor Radionuclide Therapy (PRRT) are recommended for PRRT as second-line therapy, according to the European Society for Medical Oncology (ESMO) guidelines 2

Efficacy of Radiopharmaceuticals

• Radiolabeled peptide therapy has shown objective response rates of 9-33% for neuroendocrine tumors (NETs) 1
• Objective response rates of approximately 23% have been reported for pheochromocytomas/paragangliomas 3
• Lu-177 dotatate is approved for patients with midgut NETs and pancreatic NETs, as stated in the ESMO guidelines 2
• PRRT should be used after failure of approved therapies in pancreatic NETs, according to ESMO guidelines 2

Treatment Regimens and Dosage

• Standard treatment consists of 3-4 cycles of Lutetium-177 dotatate, with retreatment being appropriate upon disease progression, as recommended by the ESMO clinical practice guidelines 2
• The recommended number of Lu-177 infusions is 3-5 cycles for neuroendocrine tumors, with cycles administered every 6-12 weeks, as suggested by the European Journal of Nuclear Medicine and Molecular Imaging 4
• The dosage of Lu-177 is 5.55-7.4 GBq (150-200 mCi) per cycle, with 3-5 cycles, and an interval between cycles of 6-12 weeks, as recommended by the European Journal of Nuclear Medicine and Molecular Imaging 4
• Example treatment regimens:

5, 2, 4

Toxicity and Monitoring

• Myelosuppression is cumulative and may be dose-limiting after repeated treatment cycles, and patients with bone marrow infiltration or previous chemotherapy/radionuclide therapy are at higher risk for severe myelotoxicity 1
• Nephrotoxicity risk increases with pre-existing microangiopathy due to hypertension or diabetes 1
• Renal toxicity is a concern, with a creatinine clearance loss of about 3.8% per year for Lu-177 dotatate, as reported in the European Journal of Nuclear Medicine and Molecular Imaging 4
• There is a risk of myelodysplastic syndrome or acute myelogenous leukemia (reported in <3% of cases) associated with Lu-177 dotatate treatment, according to the EANM guidelines 5
• Lutetium-177 (Lu-177) therapy is associated with a higher incidence of grade ≥3 adverse events, particularly anemia, thrombocytopenia, lymphopenia, and fatigue, as reported in the VISION trial 6
• The incidence of grade 3/4 neutropenia, thrombocytopenia, and lymphopenia in patients receiving Lu-177 therapy is approximately 1%, 2%, and 9%, respectively, according to the Journal for ImmunoTherapy of Cancer 7

Guideline Recommendations and Radiation Safety

• The European Society for Medical Oncology recommends close monitoring when administering alpha particle radiopharmaceuticals after LU-177, including complete blood count every 2-4 weeks after treatment, and renal and liver function tests before subsequent cycles 1
• Patients require complete blood count every 2-4 weeks after treatment, renal and liver function tests before subsequent cycles, and long-term follow-up with blood tests every 8-12 weeks for the first 12 months, as well as whole-body imaging following each cycle to document radiopharmaceutical distribution, with patient-specific dosimetry providing valuable information to assess organ-specific radiation absorbed doses 4
• Patients should follow specific radiation safety protocols, including double toilet flush after urination for 1 week following treatment, thorough hand washing after urination, and avoidance of close contact with children and pregnant women for 7 days, as recommended by the European Journal of Nuclear Medicine and Molecular Imaging 4
• Limit close contact (<3 feet) with household contacts for 2 days or with children and pregnant women for 7 days, and sleep in separate bedroom from household contacts for 3 days, from children for 7 days, or from pregnant women for 15 days, as stated by the European Journal of Nuclear Medicine and Molecular Imaging 4
• Lu-177 therapy has been shown to demonstrate significant improvement in progression-free survival and objective response rates compared to standard treatments, with manageable toxicity profiles, as recommended by the European Society for Medical Oncology and supported by the European Association of Nuclear Medicine and the National Comprehensive Cancer Network 8, 4