First-in-Humans Application of Tb-161: A Feasibility Study Using Tb-161-DOTATOC

R.P. Baum*, A. Singh, H.R. Kulkarni, P. Bernhardt, T. Ryden, C. Schuchardt, N. Gracheva, P.V. Grundler, U. Koster, D. Muller*, M. Prohl, J.R. Zeevaart, R. Schibli, N.P. van der Meulen, C. Muller*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Tb-161 has decay properties similar to those of Lu-177 but, additionally, emits a substantial number of conversion and Auger electrons. The aim of this study was to apply Tb-161 in a clinical setting and to investigate the feasibility of visualizing the physiologic and tumor biodistributions of Tb-161-DOTATOC. Methods: Tb-161 was shipped from Paul Scherrer Institute, Villigen-PSI, Switzerland, to Zentralklinik Bad Berka, Bad Berka, Germany, where it was used for the radiolabeling of DOTATOC. In 2 separate studies, 596 and 1,300 MBq of Tb-161-DOTATOC were administered to a 35-y-old male patient with a metastatic, well-differentiated, nonfunctional malignant paraganglioma and a 70-y-old male patient with a metastatic, functional neuroendocrine neoplasm of the pancreatic tail, respectively. Whole-body planar g-scintigraphy images were acquired over a period of several days for dosimetry calculations. SPECT/CT images were reconstructed using a recently established protocol and visually analyzed. Patients were observed for adverse events after the application of Tb-161-DOTATOC. Results: The radiolabeling of DOTATOC with Tb-161 was readily achieved with a high radiochemical purity suitable for patient application. Planar images and dosimetry provided the expected time-dependent biodistribution of Tb-161-DOTATOC in the liver, kidneys, spleen, and urinary bladder. SPECT/CT images were of high quality and visualized even small metastases in bones and liver. The application of Tb-161-DOTATOC was well tolerated, and no related adverse events were reported. Conclusion: This study demonstrated the feasibility of imaging even small metastases after the injection of relatively low activities of Tb-161-DOTATOC using g-scintigraphy and SPECT/CT. On the basis of this essential first step in translating Tb-161 to clinics, further efforts will be directed toward the application of Tb-161 for therapeutic purposes.
Original languageEnglish
Pages (from-to)1391-1397
Number of pages7
JournalJournal of Nuclear Medicine
Issue number10
Publication statusPublished - 1 Oct 2021


  • Tb-161
  • SPECT/CT imaging
  • Auger electrons
  • first-in-humans
  • LU-177

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