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The biology of metastatic pancreatic neuroendocrine tumors (panNET) may alter over time. It remains to be defined if, how, and when this patient group should be recommended to re-evaluate the characteristics of their disease. This prospective single-center, longitudinal cohort study at Uppsala University Hospital, Sweden (NCT03130205), included metastatic panNET patients with progressive disease to participate in a standardized re-characterization protocol: clinical and biochemical analyses, core-needle biopsy, and dual-positron emission tomography/computed tomography (PET/CT) (¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and Gallium-68 DOTATOC (⁶⁸Ga-DOTATOC)) with NETPET score assessments. At further disease progression, a second re-characterization was offered. The proportion of patients with a clinically significant change is reported and defined as information that could lead to a change in the therapeutic algorithm proposed in the European Neuroendocrine Tumor Society (ENETS) guidelines. Between 2017 and 2021, 21 patients with progressive metastatic panNETs were included. Before inclusion, 19 tumors were grade (G) 1 or 2, and two were G3. Sixteen patients underwent biopsy with collection of adequate tumor material, of whom 81.3% (n = 13/16) displayed an increase in the Ki-67 index, with transition from G2 to G3 in 50% (n = 8/16). Twelve and 15 patients were positive on ¹⁸F-FDG- and ⁶⁸Ga-DOTATOC-positron emission tomography (PET), respectively. This corresponded to NETPET grades P1 (n = 2), P2b (n = 12), and P3b (n = 1). A clinically significant change was noted among 62% (n = 13/21) of patients at first re-characterization, leading to therapy change in 7 positron emission tomography/computed tomography (PET/CT) patients. After the second re-characterization, a significant clinical change occurred in 43% (n = 3/7) with a shift in therapy for one patient. This study shows that a considerable number of progressive metastatic panNETs experience significant changes in their disease characteristics over time. This may result in a revised treatment plan and highlights the need to re-evaluate all relevant aspects of panNET disease. Such comprehensive re-characterization is particularly crucial in the context of clinical trial inclusion.

Precise anatomic localization of insulinomas is crucial for surgical treatment. Current routine noninvasive imaging techniques, including CT, MRI, and ⁶⁸Ga-DOTA-somatostatin analog (DOTA-SSA) PET/CT, have limited sensitivity. Endoscopic ultrasound is highly sensitive but invasive. In this prospective multicenter study, we compared the diagnostic accuracy of ⁶⁸Ga-NODAGA-exendin-4 (exendin) PET/CT with all routine imaging procedures for the localization of insulinomas.

Methods: Sixty-nine adults with biochemically proven adult endogenous hyperinsulinemic hypoglycemia underwent exendin PET/CT and current routine imaging. Images were evaluated in a clinical reading and in an expert reading. Image quality was determined by quantitative analysis.

Results: Based on clinical readings, the accuracy of exendin PET/CT (94.4%; 95% CI, 84.6%–98.8%) was greater than that of DOTA-SSA PET/CT (64.8%; 95% CI, 50.6%–77.3%), contrast-enhanced CT/contrast-enhanced diffusion-weighted imaging-MRI (83.3%; 95% CI, 70.7%–92.1%), and endoscopic ultrasound (82.8%; 95% CI, 64.1%–94.1%). In 13% of patients, a correct diagnosis was only reached after exendin PET/CT. Interobserver agreement between readings was higher for exendin PET/CT than for DOTA-SSA PET/CT and contrast-enhanced CT/contrast-enhanced diffusion-weighted imaging-MRI (Cohen κ, 1.0 vs. 0.5 and 0.55). Exendin PET/CT provided a higher insulinoma-to-background ratio (15.3 ± 6.7 vs. 5.2 ± 3.0) and contrast-to-noise ratio (22.6 ± 11.1 vs. 5.1 ± 3.7) than did DOTA-SSA PET/CT.

Conclusion: This study demonstrates the superiority of exendin PET/CT in a unique prospective comparison to all current routine imaging modalities for preoperative localization of benign insulinomas, providing the level of evidence needed for clinical implementation.

Tumour evolution with acquisition of more aggressive disease characteristics is a hallmark of disseminated cancer. Metastatic pancreatic neuroendocrine tumours (PanNETs) in particular may progress from a low/intermediate to a high-grade disease. The aim of this work was to understand the molecular mechanisms underlying metastatic progression as well as PanNET transformation from a low/intermediate to a high-grade disease. We performed multi-omics analysis (genome/exome sequencing, total RNA-sequencing and methylation array) of 32 longitudinal samples from six patients with metastatic low/intermediate grade PanNET. The clonal composition of tumour lesions and underlying phylogeny of each patient were determined with bioinformatics analyses. Findings were validated in post-alkylating chemotherapy samples from 24 patients with PanNET using targeted next generation sequencing. We validate the current PanNET evolutionary model with MEN1 inactivation that occurs very early in tumourigenesis. This was followed by pronounced genetic diversity on both spatial and temporal levels, with parallel and convergent tumour evolution involving the ATRX/DAXX and mechanistic target of the rapamycin (mTOR) pathways. Following alkylating chemotherapy treatment, some PanNETs developed mismatch repair deficiency and acquired a hypermutational phenotype. This was validated among 16 patients with PanNET who had high-grade progression after alkylating chemotherapy, of whom eight had a tumour mutational burden >50 (50%). In comparison, among the eight patients who did not show high-grade progression, 0 had a tumour mutational burden >50 (0%; odds ratio ‘infinite’, 95% confidence interval 1.8 to ‘infinite’, p = 0.02). Our findings contribute to broaden the understanding of metastatic/high-grade PanNETs and suggests that therapy driven disease evolution is an important hallmark of this disease.

Longitudinal changes in pancreatic neuroendocrine tumor (panNET) cell proliferation correlate with fast disease progression and poor prognosis. The optimal treatment strategy for secondary panNET grade (G)3 that has progressed from a previous low- or intermediate-grade to high-grade panNET G3 is currently unknown. This was a single-center retrospective cohort study aimed to characterize treatment patterns and outcomes among patients with secondary panNET-G3. Radiological responses were assessed using the Response Evaluation Criteria in Solid Tumors version 1.1. A total of 22 patients were included and received a median of 2 (range, 1–4) treatment lines in 14 different combinations. Median overall survival (OS) was 9 months (interquartile range (IQR): 4.25–17.5). For the 15 patients who received platinum–etoposide chemotherapy, median OS was 7.5 months (IQR: 3.75–10) and median progression-free survival (PFS) was 4 months (IQR: 2.5–5.5). The 15 patients who received conventional panNET therapies achieved a median OS of 8 months (IQR: 5–16.75) and median PFS was 5.5 months (IQR: 2.75–8.25). We observed one partial response on ¹⁷⁷Lu DOTA-TATE therapy. In conclusion, this hypothesis-generating study failed to identify any promising treatment alternatives for patients with secondary panNET-G3. This demonstrates the need for both improved biological understanding of this particular NET entity and for designing prospective studies to further assess its treatment in larger patient cohorts.

Objective: To retrospectively analyze toxicity, progression-free survival (PFS), overall survival (OS) and their determinants in patients with advanced pancreatic neuroendocrine tumors (panNETs), previously pretreated with chemotherapy, undergoing peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE.

Methods: In total, 102 patients with advanced panNETs, previously pretreated with one (67%) or several (33%) lines of chemotherapy were included, of whom 90 % had progressive disease and the majority (74.5%) with grade 2 tumors. 177Lu-DOTATATE, 7.4 GBq per cycle, was administered with 6 to 8 weeks interval, in 88 % of patients utilizing a dosimetry-guided protocol, until an absorbed dose of 23 Gy to the kidneys was reached.

Results: Mean 32±10.9 GBq per patient was administered in 1-10 cycles starting median 36 months after panNET diagnosis. Median follow-up was 34 months. Median PFS was 24 months and median OS was 42 months from start of PRRT. Independent risk factors for both progression and death were liver tumor burden >50%, more than one line of previous chemotherapy and elevated alkaline phosphatase (ALP). Resection of the primary tumor was linked to longer survival. Bone marrow toxicity grade 3-4 occurred in 10.8%. One patient (1.0 %) developed acute myeloid leukemia. Bone marrow toxicity was unrelated to type and length of previous chemotherapy, amount of administered activity and absorbed dose to the bone marrow.

Conclusion: 177Lu-DOTATATE therapy was feasible, highly effective and safe in patients with advanced panNETs heavily pretreated with chemotherapy. More than one line of chemotherapy was a therapy related independent risk factor for shorter PFS and OS.

INTRODUCTION: Little is known about how Pancreatic Neuroendocrine Tumors (PanNETs) evolve over time and if changes towards a more aggressive biology correlates with prognosis. The purpose of this study was to characterize changes PanNET differentiation and proliferation over time, and to correlate findings to overall survival (OS).

PATIENTS AND METHODS: In this retrospective cohort study we screened 475 PanNET patients treated at Uppsala University Hospital, Sweden. Sporadic patients with baseline and follow-up tumor samples were included. Pathology reports and available tissue sections were re-evaluated with regard to tumor histopathology and Ki-67 index.

RESULTS: Forty-six patients with 106 tumor samples (56 available for pathology re-evaluation) were included. Median Ki-67 index at diagnosis was 7% (range 1-38%), grade 1 n=8, grade 2 n=36, and grade 3 n=2. The median change in Ki-67 index (absolute value; follow-up - baseline) was +14% (range -11 to +80%). Increase in tumor grade occurred in 28 patients (63.6%), the majority from grade 1/2 to grade 3 (n=24, 54.5%). The patients with a high-grade progression had a median OS of 50.2 months compared to 115.1 months in patients without such progression (HR 3.89, 95% CI 1.91-7.94, P<0.001).

CONCLUSIONS: A longitudinal increase in Ki-67 index and increase in tumor grade were observed in a majority of PanNETs included in this study. We propose that increase in Ki-67 index and high-grade progression should be investigated further as important biomarkers in PanNET.

PURPOSE: Peptide receptor radionuclide therapy in patients with neuroendocrine tumours has yielded promising results. This prospective study investigated the feasibility of dosimetry of the kidneys and bone marrow during therapy and its impact on efficacy and outcome.

METHODS: Lu-DOTA-octreotate with co-infusion of a mixed amino acid solution, and cycles were repeated until the absorbed dose to the kidneys reached 23 Gy or there were other reasons for stopping therapy. The Ki-67 index was ≤2% in 47 patients (23.5%), 3-20% in 121 (60.5%) and >20% in 16 (8%).

RESULTS: In 123 patients (61.5%) the absorbed dose to the kidneys reached 23 Gy with three to nine cycles during first-line therapy; in no patient was a dose to the bone marrow of 2 Gy reached. The best responses (according to RECIST 1.1) were a complete response (CR) in 1 patient (0.5%), a partial response (PR) in 47 (23.5%), stable disease (SD) in 135 (67.5%) and progressive disease (PD) in 7 (3.5%). Median progression-free survival was 27 months (95% CI 22-30 months) in all patients, 33 months in those in whom the absorbed dose to the kidneys reached 23 Gy and 15 months in those in whom it did not. Median overall survival (OS) was 43 months (95% CI 39-53 months) in all patients, 54 months in those in whom the absorbed dose to the kidneys reached 23 Gy and 25 months in those in whom it did not. Median OS was 60 months in patients with a best response of PR or CR, 42 months in those with SD and 16 months in those with PD. Three patients (1.5%) developed acute leukaemia, 1 patient (0.5%) chronic leukaemia (unconfirmed) and 30 patients (15%) grade 3 or 4 bone marrow toxicity. Eight patients (4%) developed grade 2 kidney toxicity and one patient (0.5%) grade 4 kidney toxicity.

CONCLUSIONS: Lu-DOTA-octreotate is feasible. Patients in whom the absorbed dose to the kidneys reached 23 Gy had a longer OS than those in whom it did not. Patients with CR/PR had a longer OS than those with SD. Bone marrow dosimetry did not predict toxicity.

Mutations affecting the mechanistic target of rapamycin (MTOR) signalling pathway are frequent in human cancer and have been identified in up to 15% of pancreatic neuroendocrine tumours (NETs). Grade A evidence supports the efficacy of MTOR inhibition with everolimus in pancreatic NETs. Although a significant proportion of patients experience disease stabilization, only a minority will show objective tumour responses. It has been proposed that genomic mutations resulting in activation of MTOR signalling could be used to predict sensitivity to everolimus.

PATIENTS AND METHODS: Patients with NETs that underwent treatment with everolimus at our Institution were identified and those with available tumour tissue were selected for further analysis. Targeted next-generation sequencing (NGS) was used to re-sequence 22 genes that were selected on the basis of documented involvement in the MTOR signalling pathway or in the tumourigenesis of gastroenterpancreatic NETs. Radiological responses were documented using Response Evaluation Criteria in Solid Tumours.

RESULTS: Six patients were identified, one had a partial response and four had stable disease. Sequencing of tumour tissue resulted in a median sequence depth of 667.1 (range=404-1301) with 1-fold coverage of 95.9-96.5% and 10-fold coverage of 87.6-92.2%. A total of 494 genetic variants were discovered, four of which were identified as pathogenic. All pathogenic variants were validated using Sanger sequencing and were found exclusively in menin 1 (MEN1) and death domain associated protein (DAXX) genes. No mutations in the MTOR pathway-related genes were observed.

CONCLUSION: Targeted NGS is a feasible method with high diagnostic yield for genetic characterization of pancreatic NETs. A potential association between mutations in NETs and response to everolimus should be investigated by future studies.

Systemic therapies established in the management of patients with neuroendocrine tumors (NETs) include somatostatin analogs and interferon-alpha, also referred to as biotherapy. Recent randomized controlled studies have extended the knowledge on the frequency of side effects associated with biotherapy. More recently, novel targeted drugs, such as the mammalian target of rapamycin inhibitor everolimus and the multiple tyrosine kinase inhibitor sunitinib, have been introduced in the management of NETs. Although targeted drugs are generally well tolerated, with most adverse events being of mild to moderate severity and manageable, novel targeted drugs exhibit a distinct adverse event profile that warrants guidance for appropriate diagnostic and therapeutic management. This is particularly important given the widespread and potentially long-term use of everolimus in a broad spectrum of NETs and of sunitinib in pancreatic NETs. This review will focus on the most relevant toxicities associated with biotherapy and novel targeted drugs and on their management. For each drug class indication, administration and dosing schedule, most frequent adverse events, actions and dose adjustments for adverse events as well as their monitoring are presented. This review further covers the evaluation of treatment effect, patient information, drug interactions, and information on pregnancy.

Systemic chemotherapy is indicated in progressive or bulky advanced pancreatic neuroendocrine tumors (NETs) and in grade 3 (G3) neuroendocrine neoplasms (NENs) as per ENETS guidelines. Chemotherapy may be considered in NETs of other sites (lung, thymus, stomach, colon, and rectum) under certain conditions (e.g., when Ki-67 is at a high level [upper G2 range], in rapidly progressive disease and/or after failure of other therapies, or if somatostatin receptor imaging is negative). An ENETS Consensus Conference was held in Antibes (2015) to elaborate guidelines on the standards of care of different diagnostic procedures and therapeutic interventions in NENs. This article provides guidance on chemotherapy including therapeutic indications, dosing schedules, adverse events (including prevention and management), drug interactions, and evaluation of treatment effect for the chemotherapy agents most commonly used in NENs (streptozocin, dacarbazine, fluoropyrimidines, platinum compounds, etoposide, and irinotecan).