Peptide receptor radionuclide therapy (PRRT) is an established treatment for grade 1 and 2 gastroenteropancreatic neuroendocrine tumors with an increased uptake on somatostatin receptor imaging (SRI). Patients with metastatic high-grade (WHO G3) gastroenteropancreatic neuroendocrine neoplasms (NET G3 and NEC) represent a heterogeneous subgroup with poor prognosis and standard platinum-etoposide chemotherapy have limited therapeutic benefit. However, there is promising emerging evidence supporting the effectiveness of PRRT in SRI-positive G3 disease. A review search for studies reporting on PRRT in gastroenteropancreatic neuroendocrine neoplasms G3 was performed: four studies with more than ten cases were found. PRRT was mainly given as second- or third-line treatment in patients with progressive disease. Most patients had a pancreatic primary, 50% had well-differentiated tumors, and most had a Ki-67 <55%. Three studies showed similar results with promising response rates (31–41%) and disease control rates (69–78%). Progression-free survival (11–16 months) and survival (22–46 months) were best concerning patients with a Ki-67 <55%. Progression-free survival was 19 months in NET G3, 11 months for lowNEC (Ki-67 ≤55%) and 4 months for highNEC (Ki-67 >55%). PRRT should be considered for patients with increased uptake on SRI, both in gastroenteropancreatic NET G3 cases and as well as in NEC cases with a Ki-67 21–55%. PRRT for NEC with a Ki-67 >55% is less defined, but could be considered in highly selected cases after response to initial chemotherapy where all residual disease have high uptake on SRI. Dual tracer using 18F-FDG PET/CT and SRI provides important information for patient selection for PRRT in this heterogeneous complex high-grade disease.
Halfdan Sorbye, Grace Kong and Simona Grozinsky-Glasberg
Jan P Dumanski, Chiara Rasi, Peyman Björklund, Hanna Davies, Abir S Ali, Malin Grönberg, Staffan Welin, Halfdan Sorbye, Henning Grønbæk, Janet L Cunningham, Lars A Forsberg, Lars Lind, Erik Ingelsson, Peter Stålberg, Per Hellman and Eva Tiensuu Janson
The genetics behind predisposition to small intestinal neuroendocrine tumors (SI-NETs) is largely unknown, but there is growing awareness of a familial form of the disease. We aimed to identify germline mutations involved in the carcinogenesis of SI-NETs. The strategy included next-generation sequencing of exome- and/or whole-genome of blood DNA, and in selected cases, tumor DNA, from 24 patients from 15 families with the history of SI-NETs. We identified seven candidate mutations in six genes that were further studied using 215 sporadic SI-NET patients. The result was compared with the frequency of the candidate mutations in three control cohorts with a total of 35,688 subjects. A heterozygous variant causing an amino acid substitution p.(Gly396Asp) in the MutY DNA glycosylase gene (MUTYH) was significantly enriched in SI-NET patients (minor allele frequencies 0.013 and 0.003 for patients and controls respectively) and resulted in odds ratio of 5.09 (95% confidence interval 1.56–14.74; P value = 0.0038). We also found a statistically significant difference in age at diagnosis between familial and sporadic SI-NETs. MUTYH is involved in the protection of DNA from mutations caused by oxidative stress. The inactivation of this gene leads to specific increase of G:C- > T:A transversions in DNA sequence and has been shown to cause various cancers in humans and experimental animals. Our results suggest that p.(Gly396Asp) in MUTYH, and potentially other mutations in additional members of the same DNA excision-repair pathway (such as the OGG1 gene) might be involved in driving the tumorigenesis leading to familial and sporadic SI-NETs.
Esben Andreas Carlsen, Nicola Fazio, Dan Granberg, Simona Grozinsky-Glasberg, Hojjat Ahmadzadehfar, Chiara Maria Grana, Wouter T Zandee, Jaroslaw Cwikla, Martin A Walter, Peter Sandor Oturai, Anja Rinke, Andrew Weaver, Andrea Frilling, Sara Gritti, Anne Kirstine Arveschoug, Amichay Meirovitz, Ulrich Knigge and Halfdan Sorbye
Peptide receptor radionuclide therapy (PRRT) is an established treatment of metastatic neuroendocrine tumors grade 1–2 (G1–G2). However, its possible benefit in high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN G3) is largely unknown. We therefore aimed to assess the benefits and side effects of PRRT in patients with GEP NEN G3. We performed a retrospective cohort study at 12 centers to assess the efficacy and toxicity of PRRT in patients with GEP NEN G3. Outcomes were response rate, disease control rate, progression-free survival (PFS), overall survival (OS) and toxicity. We included 149 patients (primary tumor: pancreatic n = 89, gastrointestinal n = 34, unknown n = 26). PRRT was first-line (n = 30), second-line (n = 62) or later-line treatment (n = 57). Of 114 patients evaluated, 1% had complete response, 41% partial response, 38% stable disease and 20% progressive disease. Of 104 patients with documented progressive disease before PRRT, disease control rate was 69%. The total cohort had median PFS of 14 months and OS of 29 months. Ki-67 21–54% (n = 125) vs Ki-67 ≥55% (n = 23): PFS 16 vs 6 months (P < 0.001) and OS 31 vs 9 months (P < 0.001). Well (n = 60) vs poorly differentiated NEN (n = 62): PFS 19 vs 8 months (P < 0.001) and OS 44 vs 19 months (P < 0.001). Grade 3–4 hematological or renal toxicity occurred in 17% of patients. This large multicenter cohort of patients with GEP NEN G3 treated with PRRT demonstrates promising response rates, disease control rates, PFS and OS as well as toxicity in patients with mainly progressive disease. Based on these results, PRRT may be considered for patients with GEP NEN G3.