Australasian Gastro-Intestinal Trials Group (AGITG) STOPNET: A randomised study of cessation of somatostatin analogues after peptide receptor radionuclide therapy (PRRT) in mid, hind-gut, and pancreatic neuroendocrine tumours

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Introduction: After progressing on somatostatin analogues (SSA), patients with somatostatin receptor positive gastroenteropancreatic (GEP) NETs often receive PRRT. It is unclear whether current practice of continuing SSA after commencing PRRT is beneficial, especially in non-functioning NETs.

Aim(s): Evaluate the outcomes of SSA cessation or continuation in patients with GEP-NETs undergoing PRRT after progression on SSA. Co-primary endpoints: 20-month progression-free survival (PFS); feasibility of patient recruitment and patient acceptance of SSA cessation.

Materials and methods: STOPNET is an AGITG-led prospective, randomised, non-comparative, open-label, multi-centre phase II study in collaboration with CCTG (NCT06345079). Eligible participants must have advanced or unresectable WHO grade 1/2 non-functioning GEP-NETs (except foregut), with progressive disease on imaging after receiving ≥3 months of SSA at standard growth-control doses. Randomisation is 2:1 to SSA cessation or SSA continuation. SSA cessation arm will receive their last SSA ≥28 days prior to the first PRRT cycle. SSA continuation arm will continue to receive SSA during and after PRRT as per current practice. Sample size for the SSA cessation arm was calculated based on Fleming’s single stage design, assuming uninteresting and interesting 20-month PFS rates of 60% and 77% respectively. The study aims to enroll 78 participants across 13 sites.

Conference:

Presenting Author:

Authors: Burge M, Wyld D, Pattison D, Loree J, Goodwin R,

Keywords: Somatostatin analogue, peptide receptor radionuclide therapy, gastroenteropancreatic, neuroendocrine, non-functioning, cessation, Australasian Gastro-Intestinal Trials Group (AGITG), Canadian Cancer Trials Group (CCTG),