ECEESPE2025 Poster Presentations Endocrine Related Cancer (76 abstracts)
Individual dosimetry in radionuclide therapy (RLT) of NET using [177Lu]Lu-DOTA-TATE or [177Lu/90Y]-DOTA-TATE mixture - effect on total administered RLT activity
Marta Opalinska 1 , Maciej Kolodziej 2 , Grzegorz Kamiński 2 , Marek Dedecjus 3 , Aldona Kowalska 4 , Marek Saracyn 2 , Piotr Garnuszek 5 , Wioletta Lenda-Tracz 6 , Danuta Gąsior-Perczak 4 , Anna Borkowska 6 , Joanna Januszkiewicz-Caulier 3 , Anna Budzyńska 7 , Agata Kubik 7 , Patrycja Szubstarska 7 , Krzysztof Kacperski 7 , Wioletta Chalewska 3 , Paulina Cegła 3 , Izabela Cieszykowska 5 , Renata Mikolajczak 5 & Alicja Hubalewska-Dydejczyk 1
1Jagiellonian University Medical College, Chair and Department of Endocrinology, Kraków, Poland; 2Military Institute of Medicine - National Research Institute, Department of Endocrinology and Isotope Therapy, Warsaw, Poland; 3National Institute of Oncology, National Institute of Oncology, Warsaw, Poland; 4Jan Kochanowski University in Kielce, Collegium Medicum, Kielce, Poland; 5National Centre for Nuclear Research, Radioisotope Center POLATOM, Otwock-Świerk, Poland; 6Jagiellonian University Medical College, Faculty of Health Sciences, Kraków, Poland; 7Military Instituteof Medicine - National Research Institute, Department of Nuclear Medicine, Warsaw, Poland
JOINT1762
Introduction: Radioligand therapy (RLT) targeting somatostatin receptors is an effective treatment for disseminated neuroendocrine tumors(NETs) that express these receptors. Individual dosimetry of critical organs ensures safety and, in some cases, allows for an increased radiation dose during therapy, potentially leading to better treatment outcomes. The DUONEN multicenter randomized clinical trial aims to evaluate the effect of individual dosimetry on the efficacy and safety of RLT with [177Lu]Lu-DOTA-TATE or a mixture of [177Lu/90Y]-DOTA-TATE in patients with NET.
Materials and Methods: Adult patients with advanced, unresectable, well-differentiated(G1 and G2) NETs, who are progressing on long-acting somatostatin analogues, are randomized into four arms:
• Arm A: Treated with [177Lu]Lu-DOTA-TATE at a constant radioactivity of 7400MBq per cycle
• Arm B: Treated with a mixture of [177Lu/90Y]-DOTA-TATE, initially in a 3700:1850MBq/MBq ratio, with the [90Y]Y-DOTA-TATE dose adjusted in each cycle based on individual dosimetry to maintain the highest possible radiation dose in tumor tissue
• Arm C: Similar to Arm B, but with the radioactivity of [177Lu]Lu-DOTA-TATE adjusted according to dosimetry, while the radioactivity of [90Y]Y-DOTA-TATE remains constant
• Arm D: The first dose is analogous to arm A, with subsequent doses individualized based on dosimetryThe overall dose limits for four cycles of RLT are <23Gy for the kidneys and <2Gy for the red bone marrow.
Results: By now dosimetry was performed for 115cycles of RLT in 40patients (10 per arm) using QDose software based on 4 SPECT/CT scans and 5 blood samples. In all arms, the doses to the red bone marrow did not exceed the critical limits, with most cases being considerably lower. There was significant variability in the individual doses absorbed by the kidneys. The average dose for kidneys equaled 0. 64 Gy/GBq (SD 0. 19) in arms A and D whereas in arms B and C 0. 76 Gy/GBq (SD 0. 29), and 3. 26 Gy/GBq (SD 1. 26) for [177Lu]Lu-DOTA-TATE and [90Y]Y-DOTA-TATE, respectively. Considering the standard activity of 7. 4GBq in the first cycle, the activity in subsequent cycles could be increased by more than 10% in 60% of cases and decreased in about 15% of cases.
Conclusion: Individual dosimetry may play an important role in RLT, leading to significant dose adjustments in subsequent cycles of treatment for most patients. This approach frequently allows for significant dose increases in subsequent cycles of [177Lu]Lu-DOTA-TATE therapy and suggested dose reductions in the arms using mixtures of [177Lu/90Y]-DOTA-TATE.
Acknowledgments: The study was funded by the Polish Medical Research Agency (Project number 2019/ABM/01/00077-00).
Volume 110
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Endocrine Abstracts
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