Targeted beta- plus auger and conversion electron therapy with terbium-161 labelled somatostatin receptor antagonist DOTA-LM3 – BETA plus phase 0 study

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Introduction: Radioligand therapy with lutetium-177 labelled somatostatin receptor (SSTR) agonists (177Lu-DOTATATE or 177Lu-DOTATOC) showed limited response rate and durability. The novel SSTR antagonist DOTA-LM3 labelled with terbium-161, which co-emits conversion and Auger electrons in addition to β- particles, potentially increasing tumour doses and offering a more effective treatment for micro metastases.

Aim(s): Evaluation of tumour and organ absorbed doses of 161Tb-DOTA-LM3 in comparison to 177Lu-DOTATOC in 8 patients with advanced, progressive SSTR-positive grade 1 and 2 gastroenteropancreatic neuroendocrine tumours.

Materials and methods: In this randomised, cross-over, prospective, single-centre, open-label Phase 0 study (NCT05359146) all patients received 1 GBq 161Tb-DOTA-LM3 and 1 GBq 177Lu-DOTATOC over a 4-week interval. Primary endpoint: imaging-based tumour and organ absorbed doses (3D dosimetry using a Monte-Carlo-based OSEM reconstruction); secondary endpoint: safety (CTCAE V5.0 criteria).

Conference:

Presenting Author: Fricke J

Authors: Fricke J, Westerbergh F, McDougall L, Christ E, Nicolas G,

Keywords: Radionuclide therapy, PRRT, Auger electrons, Conversion electrons, Terbium-161, radiolabelled somatostatin antagonist, neuroendocrine tumour,