Background: Peptide receptor radionuclide therapy (PRRT) is an established treatment of metastatic low-grade and intermediate-grade neuroendocrine tumors (G1-G2). However, its possible benefit in high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN G3: NET G3 and NEC) has been unknown.
Methods: Data from 3 recent retrospective studies (Thang et al. 2018, Zhang et al. 2018, Carlsen et al. 2019) on efficacy and toxicity of PRRT in patients with GEP NEN G3 were assessed. All patients had a high uptake on somatostatin receptor imaging and most had progressive disease.
Results: The 3 studies (one multicenter) included in total 249 patients, mainly pancreatic primaries (6069%). Treatment was mainly given as 2nd or 3rd line therapy. Response rates were 3144%. Disease control rate (DCR) was 6978%. Grade 3-4 hematological or renal toxicity occurred in 1%, 16% and 17% of patients. Progression free survival (PFS) and overall survival (OS) was higher in patients with Ki-67 2155% vs Ki-67 >55%: PFS 1116 m vs 46 months and OS 2246 m vs 79 months. In the multicenter study, patients with well differentiated tumors (NET G3, n=60) had a better PFS and OS compared to poorly differentiated carcinomas (NEC, n=62): PFS 19 vs 8 months (P<0.001) and OS 44 vs 19 months (P<0.001).
Conclusion: Three retrospective cohorts of patients with GEP NEN G3 treated with PRRT demonstrates quite similar results with promising response rates, disease control rates, PFS and OS in patients with mainly progressive disease. Based on these results, PRRT may be considered for patients with high-grade GEP NEN G3 (NET G3 and NEC).
18 - 21 May 2019
European Society of Endocrinology