Undergoing Peptide Receptor Radionuclide Therapy Research Articles

Quantitative SPECT/CT Imaging of (177)Lu with In Vivo Validation in Patients Undergoing Peptide Receptor Radionuclide Therapy.

The purpose of this study is to extend an established SPECT/CT quantitation protocol to (177)Lu and validate it in vivo using urine samples, thus providing a basis for 3D dosimetry of (177)Lu radiotherapy and improvement over current planar methods which improperly account for anatomical variations, attenuation, and overlapping organs. In our quantitation protocol, counts in images reconstructed using an ordered subset-expectation maximization algorithm are converted to kilobecquerels per milliliter using a calibration factor derived from a phantom experiment. While varying reconstruction parameters, we tracked the ratio of image to true activity concentration (recovery coefficient, RC) in hot spheres and a noise measure in a homogeneous region. The optimal parameter set was selected as the point where recovery in the largest three spheres (16, 8, and 4 ml) stagnated, while the noise continued to increase. Urine samples were collected following 12 SPECT/CT acquisitions of patients undergoing [(177)Lu]DOTATATE therapy, and activity concentrations were measured in a well counter. Data was reconstructed using parameters chosen in the phantom experiment, and estimated activity concentration from the images was compared to the urine values to derive RCs. In phantom data, our chosen parameter set yielded RCs in 16, 8, and 4 ml spheres of 80.0, 74.1, and 64.5 %, respectively. For patients, the mean bladder RC was 96.1 ± 13.2% (range, 80.6-122.4 %), with a 95 % confidence interval between 88.6 and 103.6 %. The mean error of SPECT/CT concentrations was 10.1 ± 8.3% (range, -19.4-22.4 %). Our results show that quantitative (177)Lu SPECT/CT in vivo is feasible but could benefit from improved reconstruction methods. Quantifying bladder activity is analogous to determining the amount of activity in the kidneys, an important task in dosimetry, and our results provide a useful benchmark for future efforts.

Differences in the sensitivity of pretherapy and post-therapy scans in patients undergoing peptide receptor radionuclide therapy

Minutoli, Fabio; Sindoni, Alessandro; Cardile, Davide; Baldari, Sergio Author Information

Prognosis of neuroendocrine tumor patients with carcinoid heart disease undergoing Peptide Receptor Radionuclide Therapy – does the heart matter? – PRRT in carcinoid heart disease – does the Tricuspid valve insufficency matters

Prognosis of neuroendocrine tumor patients with carcinoid heart disease undergoing Peptide Receptor Radionuclide Therapy – does the heart matter? – PRRT in carcinoid heart disease – does the Tricuspid valve insufficency matters

Year Book of Dermatology

The objective of this study was to assess the safety, dosimetry, and efficacy of the ¹⁷⁷Lu-labeled somatostatin receptor (SSTR) antagonist DOTA-p-Cl-Phe-cyclo (D-Cys-Tyr-D-4-amino-Phe(carbamoyl)-Lys-Thr-Cys)D-Tyr-NH2 (¹⁷⁷Lu-DOTA-LM3) in patients with metastatic neuroendocrine neoplasms (NENs). <b>Methods:</b> Fifty-one patients (age 27–76, mean 51.6±13.9 years) with metastatic NENs underwent peptide receptor radionuclide therapy (PRRT) with ¹⁷⁷Lu-DOTA-LM3 between August 2017 and December 2019. The median administered activity per cycle was 6.1±0.88 GBq (range 2.8–7.4 GBq). ⁶⁸Ga-NODAGA-LM3 PET/CT was used for patient selection and follow-up after ¹⁷⁷Lu-DOTA-LM3 PRRT. Morphologic and molecular responses were evaluated in accordance with RECIST 1.1 and European Organization for Research and Treatment of Cancer (EORTC) criteria. Treatment-related adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. Dosimetry was performed in 11 patients and compared with the SSTR agonist ¹⁷⁷Lu-DOTATOC in 247 patients undergoing PRRT on the same dosimetry protocol. <b>Results:</b> Higher uptake and a longer effective half-life of ¹⁷⁷Lu-DOTA-LM3 was found for whole-body as well as kidneys, spleen, and metastases, resulting in higher mean absorbed organ and tumor doses as compared to the agonist ¹⁷⁷Lu-DOTA-TOC. All patients tolerated therapy without any serious acute adverse effects. Mild nausea without vomiting was observed in 5 (9.8%) patients; no other symptoms were reported. The most severe delayed adverse event was CTC-3 thrombocytopenia in 3 (5.9%) patients. Neither CTC-4 thrombocytopenia nor CTC-3-4 anemia or leukopenia was observed after treatment. No significant decline in renal function was observed, nor was hepatotoxicity. According to RECIST 1.1, disease control could be reached in 40 patients (disease control rate, 85.1%) of 47 patients monitored after ¹⁷⁷Lu-DOTA-LM3 PRRT, with a partial response in 17 (36.2%) and stable disease in 23 (48.9%), whereas 7 (14.9%) patients had progressive disease, and by EORTC criteria, complete remission in 2 (4.3%), partial remission in 21 (44.7%), stable disease in 18 (38.3%), and progressive disease in 6 (12.8%) patients. <b>Conclusion:</b> “Antagonist PRRT” with ¹⁷⁷Lu-DOTA-LM3 could be administered without severe adverse effects and was well tolerated by the majority of patients, with thrombocytopenia occurring only in a few patients. No other severe adverse effects were observed, particularly no nephrotoxicity. The SSTR antagonist ¹⁷⁷Lu-DOTA-LM3 appears to be very promising for PRRT, provides favorable biodistribution and higher tumor radiation doses than SSTR agonists, and was very effective in treating advanced metastatic NENs, especially in patients with low or no SSTR agonist binding, even achieving complete remission in some patients.