ABSTRACT
ABSTRACT: In a recent 99m Tc-HYNIC-PSMA study conducted at our department, we examined 2 patients with prostate cancer referred for initial staging on the same day. The whole-body scans revealed radiotracer uptake in the gastric mucosa and thyroid glands, alluding to high levels of free TcO 4- in the injected vial. The scans were repeated after confirming acceptable radiopharmaceutical purity of 97% (normal range, 95%-100%). Interestingly, 1 patient had liver metastases at presentation, which remained non-PSMA-avid after repeating the scan. We have reviewed this pitfall, which has been reported with many radiotracers, yet not reported with PSMA tracers.
Subject(s)
Organotechnetium Compounds , Prostatic Neoplasms , Humans , Male , Prostatic Neoplasms/diagnostic imaging , Aged , Glutamate Carboxypeptidase II/metabolism , Whole Body Imaging , Middle Aged , Antigens, SurfaceABSTRACT
Merkel cell carcinoma is a rare, aggressive skin malignancy, also known as neuroendocrine carcinoma of the skin, with high rates of recurrence and distant metastasis. In refractory metastatic Merkel cell carcinoma (mMCC), besides immunotherapy, chemotherapy, and radiation, peptide receptor radionuclide therapy (PRRT) may be a viable option since this type of tumor can express somatostatin receptors. Methods: We performed a comprehensive review of the literature to evaluate the efficacy of PRRT in mMCC patients. Results: Thirty-seven patients with mMCC received PRRT (1-5 cycles) with 177Lu- or 90Y-labeled somatostatin analogs (cumulative activity, 1.5-30 GBq). Radiographic response was available for 19 of 28 patients who received PRRT alone. Six (31.6%) of 19 patients showed objective responses, from partial to complete, and no severe adverse events were reported. Conclusion: Our analysis supports the use of PRRT in mMCC with sufficient somatostatin receptor uptake, although the quality of the available evidence is low. Prospective clinical trials are already in development and have started accruing in some parts of the world.
Subject(s)
Carcinoma, Merkel Cell , Neuroendocrine Tumors , Organometallic Compounds , Skin Neoplasms , Humans , Neuroendocrine Tumors/pathology , Carcinoma, Merkel Cell/chemically induced , Carcinoma, Merkel Cell/drug therapy , Prospective Studies , Retrospective Studies , Receptors, Somatostatin/metabolism , Skin Neoplasms/chemically induced , Skin Neoplasms/drug therapy , Radioisotopes , Octreotide/therapeutic use , Organometallic Compounds/therapeutic useABSTRACT
ABSTRACT: A 70-year-old man with mCRPC (metastatic castration-resistant prostate cancer) was referred for 68 Ga-PSMA PET/CT for restaging and the possibility of targeted molecular radioligand therapy with 177 Lu-PSMA. Numerous 68 Ga-PSMA-avid skeletal metastases with low SUVs were noted. Because of low PSMA expression, a 68 Ga-FAPI-46 PET/CT was performed to evaluate the eligibility for FAPI-based radioligand therapy. There were some discordant findings between 68 Ga-PSMA and 68 Ga-FAPI PET/CT scans regarding the detectability of lesions and SUVs. Our case signifies that 68 Ga-FAPI theragnostic may have a potential role in the treatment of mCRPC patients with insignificant PSMA expression or in cases after the failure of 177 Lu-PSMA therapy.
Subject(s)
Positron Emission Tomography Computed Tomography , Prostatic Neoplasms, Castration-Resistant , Aged , Dipeptides , Gallium Radioisotopes , Heterocyclic Compounds, 1-Ring , Humans , Lutetium , Male , Prostate-Specific Antigen/metabolism , Prostatic Neoplasms, Castration-Resistant/diagnostic imaging , Prostatic Neoplasms, Castration-Resistant/metabolism , Prostatic Neoplasms, Castration-Resistant/radiotherapy , Quinolines , Radioisotopes , Radiopharmaceuticals , Treatment OutcomeABSTRACT
A 56-year-old man with metastatic castration-resistant prostate cancer was referred for radioligand therapy with Lu-prostate-specific membrane antigen. In the third cycle, a posttherapy whole-body scan showed unexpected skeletal and joint uptake apart from his known metastatic lesions. This observation raised suspicion for possible impurity (mainly free lutetium) in the applied radiopharmaceutical product. After contacting the radiopharmaceutical company, we were informed that the radiochemical purity of the used batch of Lu-prostate-specific membrane antigen had been 95%. This is the first report of excess free lutetium scan pattern and its complications in a patient undergoing radioligand therapy.
Subject(s)
Chlorides/metabolism , Dipeptides , Heterocyclic Compounds, 1-Ring , Prostatic Neoplasms, Castration-Resistant/diagnostic imaging , Prostatic Neoplasms, Castration-Resistant/pathology , Whole Body Imaging , Artifacts , Humans , Lutetium , Male , Middle Aged , Neoplasm Metastasis , Prostate-Specific Antigen , Prostatic Neoplasms, Castration-Resistant/metabolism , Treatment OutcomeABSTRACT
A 77-year-old man with a history of metastatic Merkel cell carcinoma and debilitating painful cutaneous lesions was referred to our nuclear medicine department for peptide receptor radionuclide therapy with Lu-DOTATATE as ultimate therapeutic option. Post-treatment whole body scan showed multiple zones of Lu-DOTATATE uptake in the metastatic regions, which revealed significant improvement within the next 10 days of therapy. Peptide receptor radionuclide therapy in metastatic Merkel cell carcinoma is an effective therapeutic option that should be considered in earlier stages of the disease.
