RT Journal Article SR Electronic T1 Evaluation of Safety and Dosimetry of 177Lu-DOTA-ZOL for Therapy of Bone Metastases JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1126 OP 1132 DO 10.2967/jnumed.120.255851 VO 62 IS 8 A1 Fernández, René A1 Eppard, Elisabeth A1 Lehnert, Wencke A1 Jiménez-Franco, Luis David A1 Soza-Ried, Cristian A1 Ceballos, Matías A1 Ribbeck, Jessica A1 Kluge, Andreas A1 Rösch, Frank A1 Meckel, Marian A1 Zhernosekov, Konstantin A1 Kramer, Vasko A1 Amaral, Horacio YR 2021 UL http://jnm.snmjournals.org/content/62/8/1126.abstract AB Palliative treatment of bone metastasis using radiolabeled bisphosphonates is a well-known concept proven to be safe and effective. A new therapeutic radiopharmaceutical for bone metastasis is 177Lu-DOTA-zoledronic acid (177Lu-DOTA-ZOL). In this study, the safety and dosimetry of a single therapeutic dose of 177Lu-DOTA-ZOL were evaluated on the basis of a series of SPECT/CT images and blood samples. Methods: Nine patients with exclusive bone metastases from metastatic castration-resistant prostate cancer (mCRPC) (70.8 ± 8.4 y) and progression under conventional therapies participated in this prospective study. After receiving 5,780 ± 329 MBq 177Lu-DOTA-ZOL, patients underwent 3-dimensional whole-body SPECT/CT imaging and venous blood sampling over 7 d. Dosimetric evaluation was performed for main organs and tumor lesions. Safety was assessed by blood biomarkers. Results: 177Lu-DOTA-ZOL showed fast uptake and high retention in bone lesions and fast clearance from the bloodstream in all patients. The average retention in tumor lesions was 0.02% injected activity per gram at 6 h after injection and approximately 0.01% at 170 h after injection. In this cohort, the average absorbed doses in bone tumor lesions, kidneys, red bone marrow, and bone surfaces were 4.21, 0.17, 0.36, and 1.19 Gy/GBq, respectively. The red marrow was found to be the dose-limiting organ for all patients. A median maximum tolerated injected activity of 6.0 GBq may exceed the defined threshold of 2 Gy for the red bone marrow in individual patients (4/8). Conclusion: 177Lu-DOTA-ZOL is safe and has a favorable therapeutic index compared with other radiopharmaceuticals used in the treatment of osteoblastic bone metastases. Personalized dosimetry, however, should be considered to avoid severe hematotoxicity for individual patients.