Radiolabelled somatostatin receptor (SSTR) antagonist vs. agonist for peptide receptor radionuclide therapy (PPRT) in patients with SSTR positive neuroendocrine tumours – A retrospective basket study

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Introduction: PRRT with lutetium-177 labelled somatostatin receptor (SSTR) agonists ([177Lu]Lu-DOTATATE or [177Lu]Lu-DOTATOC (177Lu-TOC) has limited response rate and durability. The SSTR antagonist [177Lu]Lu-DOTA-JR11 (177Lu-JR11) offers potentially increased tumour doses with better efficacy.

Aim(s): Intrapatient comparison of tumour and organ absorbed doses and medium progression-free survival (PFS) after therapy with 177Lu-TOC and 177Lu-JR11 in patients with therapy resistant metastatic neuroendocrine tumours (NETs).

Materials and methods: In this preplanned retrospective, single-centre, open-label study, 15 consecutive patients with metastatic NETs and a PFS of ≤ 12 months after last round 177Lu-TOC PRRT were included. These patients received as a rechallenge one cycle 177Lu-TOC (5.1- 7.4 GBq) followed by 1-2 cycles 177Lu-JR11 (2.7-4.8 GBq/cycle) in an interval of 10 weeks. Endpoints: imaging-based tumour and kidney absorbed doses (3D dosimetry using Olinda), safety (CTCAE V5.0 criteria) and PFS (follow-up morphological imaging every ~3 months).

Conference:

Presenting Author: Eigler C

Authors: Eigler C, Mushaweh A, McDougall L, Bauman A, Christ E,

Keywords: Somatostatin Receptor, Neuroendocrine Tumour, DOTA-JR11, DOTA-TOC, Peptide Receptor Radionuclide Therapy,