Peptide receptor radionuclide therapy as a potential tool for neoadjuvant therapy in patients with inoperable neuroendocrine tumours (NETs)

Contemporary Approaches to the Surgical Management of Pancreatic Neuroendocrine Tumors

The incidence of pancreatic neuroendocrine tumors (PNETs) is on the rise primarily due to the increasing use of cross-sectional imaging. Most of these incidentally detected lesions are non-functional PNETs with a small proportion of lesions being hormone-secreting, functional neoplasms. With recent advances in surgical approaches and systemic therapies, the management of PNETs have undergone a paradigm shift towards a more individualized approach. In this manuscript, we review the histologic classification and diagnostic approaches to both functional and non-functional PNETs. Additionally, we detail multidisciplinary approaches and surgical considerations tailored to the tumor's biology, location, and functionality based on recent evidence. We also discuss the complexities of metastatic disease, exploring liver-directed therapies and the evolving landscape of minimally invasive surgical techniques.

Efficacy and safety of neoadjuvant therapy in gastroenteropancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

To determine the effectiveness and safety of neoadjuvant therapy in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) and provide evidence-based suggestions for clinical treatment.

METHODS

The Cochrane Library, Embase, PubMed, and Web of Science were searched for articles published that analyzed the effectiveness and safety of GEP-NEN-targeted neoadjuvant therapy before March 2023. A confidence interval (CI) of 95%, a subgroup analysis, heterogeneity, and effect size (ES) were analyzed, and a meta-analysis of the literature was performed using the Stata BE17 software.

RESULTS

A total of 417 patients from 13 studies were included in this meta-analysis. The primary variables comprised the objective response rate (ORR), disease control rate (DCR), surgical resection rate, and R0 resection rate with ES values of 0.42 (95% CI: 0.25-0.60), 0.96 (95% CI: 0.93-0.99), 0.67 (95% CI: 0.50-0.84), and 0.60 (95% CI: 0.54-0.67), respectively. The secondary variables were the incidence rates of treatment-related adverse events (TRAEs), Grade 3 or higher TRAEs, and surgical complications with ES values of 0.29 (95% CI: -0.03-0.21), 0.13 (95% CI: -0.07-0.33), and 0.35 (95% CI: 0.27-0.44), respectively.

CONCLUSION

Neoadjuvant therapy is an effective and safe treatment method for GEP-NENs. However, further studies are required to determine the optimal regimen for this therapy in these tumors.

Neoadjuvant Peptide Receptor Radionuclide Therapy in a Rare Case of Pediatric Primary Hepatic Gastrinoma

ABSTRACT

Gastrinomas with predilection for the adult male population are located in the gastrinoma triangle (>90%). Primary hepatic gastrinoma especially in pediatric population is very rare. Peptide receptor radionuclide therapy has shown benefit in metastatic gastroenteropancreatic neuroendocrine tumors (NETs) with an increasing interest in expanding its role as neoadjuvant treatment modality to improve the surgical candidature in inoperable NETs. There is currently no literature supporting its role in the pediatric NET patients. We present a rare case of a young boy with primary hepatic gastrinoma where 177Lu-based peptide receptor radionuclide therapy in the neoadjuvant setting contributed to his final disease-free status.

Extended peptide receptor radionuclide therapy: evaluating nephrotoxicity and therapeutic effectiveness in neuroendocrine tumor patients receiving more than four treatment cycles

PURPOSE

Currently, the most used peptide receptor radionuclide therapy (PRRT) regimen for neuroendocrine tumors comprises 4 treatment cycles, and there is not enough large-scale data to support the safety of more individualized extended PRRT. This study aims to evaluate the therapeutic effectiveness and potential nephrotoxicity related to PRRT using more than four treatment cycles.

METHODS

In this retrospective analysis, we included patients who had received at least four PRRT cycles and had available follow-up data. We analyzed renal function indicators before and after multiple treatments, comparing nephrotoxicity in patients receiving four cycles ("standard") with those receiving more than four ("extended treatment"). Nephrotoxicity was assessed via creatinine levels and CTCAE creatinine grades. Treatment effectiveness was gauged using Kaplan-Meier survival analysis, focusing on overall survival and disease-specific survival (DSS). Statistical analyses were performed using SPSS version 26 (IBM), R 4.2.3, and GraphPad Prism 9.0.0. Statistical significance was defined as a P-value of less than 0.05.

RESULTS

Our study cohort consisted of 281 patients in the standard group and 356 in the extended treatment group. No significant differences in baseline characteristics or renal function were noted between the two groups pre-treatment. Mean post-treatment creatinine levels did not significantly differ between the standard (89.30 ± 51.19 μmol/L) and extended treatment groups (93.20 ± 55.98 μmol/L; P = 0.364). Similarly, there was no statistical significance between the CTCAE creatinine grades of the two groups (P = 0.448). Adverse renal events were observed in 0.4% of patients in the standard group and 1.1% in the extended treatment group. After a median follow-up time of 88.3 months, we found that median overall survival was significantly higher in the extended treatment group (72.8 months) compared to the standard treatment group (52.8 months). A Cox regression analysis further supported these findings, indicating a better prognosis for the extended treatment group in terms of overall survival (HR: 0.580, P < 0.001) and DSS (HR: 0.599, P < 0.001).

CONCLUSION

Our findings suggest that extending PRRT treatment beyond the standard four cycles may be a safe and effective therapeutic strategy for NET patients. This approach could be particularly beneficial for patients experiencing disease recurrence or progression following standard treatment.

Pathological complete response of initially unresectable multiple liver metastases achieved using combined peptide receptor radionuclide therapy and somatostatin analogs following pancreatic neuroendocrine tumor resection: a case report

BACKGROUND

Peptide receptor radionuclide therapy (PRRT) serves as a novel and effective treatment option for somatostatin receptor-positive unresectable liver metastases of pancreatic neuroendocrine tumors (PNETs). However, there are few reported cases of surgical resection for initially unresectable liver metastases of PNET that were converted to resectable after PRRT. Here we report a case where PRRT and somatostatin analogs (SSAs) led to a pathological complete response of initially unresectable multiple liver metastases following PNET resection.

CASE PRESENTATION

A 52-year-old man underwent pylorus-preserving pancreaticoduodenectomy for PNET at age 40 and subsequent hepatectomies for resectable liver metastases at 44 and 47 years of age. At age 48, a follow-up examination revealed unresectable multiple liver metastases, and PRRT with 177Lu-DOTATATE therapy was initiated. After four cycles of PRRT, most liver metastases diminished according to imaging studies, and the remaining two hepatic lesions continued to shrink with additional lanreotide. Conversion surgery for liver metastases was successfully performed, revealing no viable tumor cells in tissue specimens. Seventeen months after surgery, imaging showed no detectable residual tumor or recurrence. We present a review of the relevant literature that highlights the significance of our findings.

CONCLUSIONS

This rare case highlights the pathological complete response of initially unresectable multiple liver metastases achieved by PRRT and SSAs following PNET resection, suggesting their potential as a multimodality treatment option for unresectable PNET.

Peptide receptor radionuclide therapy (PRRT) in metastatic neuroendocrine tumors of unknown primary (CUP-NETs)

Rationale: Peptide receptor radionuclide therapy (PRRT) for the treatment of neuroendocrine tumors (NETs) has been explored for more than two decades, but there are only limited data on the treatment of NETs of unknown primary site (CUP-NETs). This study aimed to analyze the long-term outcome, efficacy, and safety of PRRT in patients with CUP-NETs. Methods: Patients with pathologically confirmed metastatic CUP-NET who received lutetium-177 (177Lu) and/or yttrium-90 (90Y) labeled somatostatin analogs between March 2001 and March 2019 were retrospectively reviewed; those patients were referred as cCUP-NETs (clinical CUP-NETs). Eighty-one patients had unknown primary tumors even after [68Ga]Ga-SSTR and [18F]FDG PET/CT and were classified as pCUP-NETs (PET CUP-NETs). Treatment response was assessed according to RECIST 1.1 and PERCIST. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier analysis, and adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. Results: A total of 575 PRRT cycles were administered to 156 patients (76 men and 80 women) evaluable for analysis: these patients were monitored for a median period of 92.3 mo (range, 4.0-169.1 mo). The disease control rate was 41.4% (43.4%) by RECIST and 40.2% (40.8%) by PERCIST in cCUP-NENs (pCUP-NETs). The objective response rate (ORR) with PRRT was 29.4% and 32.2% in cCUP-NENs and pCUP-NETs, respectively. The median PFS and OS for the entire cohort were 17.4 mo (95% confidence interval [95% CI], 11.4-23.4) and 67.4 mo (95% CI, 47.2-87.2) for all patients, respectively. The median OS for G3 tumors was significantly lower (15 mo) than for patients with G1 NET (85.5 mo), G2 (71.7 mo), and for patients with unknown grade (63.3 mo) NETs (P = 0.186, HR: 10.6, 95% CI: 3.87, 28.97, P = 0.09). PRRT was well tolerated by all patients. During treatment and long-term follow-up, CTCAE grade 3 and grade 4 thrombocytopenia and leukocytopenia were observed in only 3 patients (1.9%); there was no evidence of renal or hepatic toxicity. Conclusion: In a large cohort of patients with advanced CUP-NETs treated with PRRT in a real-world scenario and followed up to 14 years after the commencement, PRRT has demonstrated favorable and clinically significant efficacy and survival with minimal and acceptable side effects. Our results indicate that PRRT is a well-tolerated and effective treatment option for patients with metastatic CUP-NETs expressing somatostatin receptors.

Neoadjuvant therapy in pancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

Background and Objectives

Neoadjuvant therapy plays an increasingly important role in pancreatic neuroendocrine neoplasms (pNENs), but the systematic evaluation of its efficacy is still lacking. The purpose of this study is to explore the role of neoadjuvant therapy in pNENs.

Methods

We systematically reviewed the literatures published online until October 1, 2021. Meta-analysis was conducted to generate proportion with 95% confidence intervals (95% CI) for tumor response, resection rate, R0 resection rate and survival time.

Results

Nine studies with 468 patients were involved in the systematic review. None of these patients met complete response (CR). Furthermore, 43.6% (95% CI [18.1, 69.0]) patients were expected to achieve partial response (PR), 51.3% (95% CI [27.9, 78.3]) to stable disease (SD), and 4.3% (95% CI [0.7, 7.9]) to progressive disease (PD). The estimate resection rate and R0 resection rate after neoadjuvant therapy were 68.2% (95% CI [44.5, 91.9]) and 60.2% (95% CI [53.5, 66.9]), respectively. There was no significant difference in resection rate between different chemotherapy regimens (41.67% vs 33.93%, P=0.453), as well as R0 resection rate (62.50% vs 68.30%, P=0.605). In terms of objective response rate (ORR), there was no significant difference between CAPTEM and FAS (41.67% vs 33.93%, P=0.453), while PRRT showed a higher ORR compared with chemotherapy, although there was also no statistical difference (49.06% vs 36.96%, P=0.154).

Conclusion

Neoadjuvant therapies could reduce the tumor size and stage of some borderline resectable or unresectable pNENs, and give some patients the chance of radical resection. However, according to the current data, the best treatment regimen for pNENs neoadjuvant therapy is still unknown.

Prospective Cohort Real-World Study on Neuroendocrine Tumor Patient's Quality of Life During Peptide Receptor Radionuclide Therapy With 177Lu-DOTATATE

OBJECTIVE

The aim of this study was to report lutetium-177 (177Lu)-DOTATATE radionuclide therapy from a patient perspective and their health-related quality of life.

METHODS

This prospective cohort study, including adult patients treated with 177Lu-DOTATATE. At the beginning of the follow-up (T1), socioeconomic and clinical information was collected, and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaires C30-v3 and GI.NET21 were applied. Follow-up was performed at the third cycle (T2) and 3 months after the end of treatment (T3). Student t test for paired samples was used to compare quality of life at T1, T2, and T3.

RESULTS

Thirty-eight patients with stage IV disease and mean age of 52.54 (standard deviation, 12.49) years were included. The most prevalent site was the gastrointestinal tract (39.7%). Global health improved between T2 and T3 (P = 0.022) and T1 and T3 (P = 0.038). Functional scales did not indicate significant changes between the periods. Regarding symptoms, significant improvements in nausea and vomiting and gastrointestinal symptoms were observed between T2 and T3 (P = 0.012 and 0.029) and T1 and T3 (P = 0.012 and 0.011), respectively.

CONCLUSIONS

177Lu-DOTATATE therapy improved global health and reduced disease-related symptoms in NET patients, positively impacting health-related quality of life.

Current status of surgical management of patients with gastroenteropancreatic neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) of the gastroenteropancreatic system are rare and heterogeneous tumours, yet with increasing prevalence. The most frequent primary sites are the small intestine, rectum, pancreas, and stomach. For a localized disease, surgical resection with local lymph nodes is usually curative with good overall and disease free survival. More complex situation is the treatment of locally advanced lesions, liver metastases, and, surprisingly, small asymptomatic tumours of the rectum and pancreas. In this review, we focus on the current role of surgical management of gastroenteropancreatic NENs. We present surgical approach for the most frequent primary sites. We highlight the role of endoscopic surgery and the watch-and-wait strategy for selected cases. As liver metastases pose an important clinical challenge, we present current indications and contraindications for liver resection and a role of liver transplantation for metastatic NENs.

Induction therapy with 177Lu-DOTATATE procures long-term survival in locally advanced or oligometastatic pancreatic neuroendocrine neoplasm patients

PURPOSE

Peptide receptor radionuclide therapy (PRRT) with ¹⁷⁷Lu-DOTATATE induces objective response in up to 57% of pancreatic neuroendocrine neoplasms (panNENs). Therefore, PRRT may comprise a downstaging option for panNEN patients who are not eligible for upfront curative surgery or are at high risk for recurrence. The aim of this study was to assess the potency of induction PRRT for locally advanced panNENs and to evaluate the effect of surgery after PRRT on overall survival (OS).

METHODS

Retrospective cohort study of panNEN patients treated with induction ¹⁷⁷Lu-DOTATATE.

RESULTS

After PRRT, 26 out of 49 patients underwent pancreatic surgery with curative intent (PRRT + surgery). Partial objective response was obtained in 62% of the PRRT + surgery group versus 26% of the patients not undergoing panNEN surgery (PRRT-only group, p = 0.02). Downstaging in tumour-vessel interface was observed in 38% of all patients with at least one involved vessel. Median OS was 14.7 years (95% CI 5.9-23.6) for the PRRT + surgery group compared to 5.5 years (95% CI 4.5-6.5) for the PRRT-only group (p = 0.003). In the Cox proportional hazards analysis, surgery was not significantly associated with OS after propensity score adjustment with cumulative activity, performance status, tumour size after PRRT, and tumour grade. Median progression-free survival was 5.3 years (95% CI 2.4-8.1) for the PRRT + surgery group and 3.0 years (95% CI 1.6-4.4) for the PRRT-only group (p = 0.02).

CONCLUSION

Early administration of PRRT followed by surgery is associated with favourable long-term outcomes in patients with locally advanced or oligometastatic panNEN and can be considered for selected patients with vascular involvement and/or increased risk of recurrence.

Predictive Factors for Resistant Disease with Medical/Radiologic/Liver-Directed Anti-Tumor Treatments in Patients with Advanced Pancreatic Neuroendocrine Neoplasms: Recent Advances and Controversies

Simple Summary

Tumor resistance, both primary and acquired, is leading to increased complexity in the nonsurgical treatment of patients with advanced panNENs, which would be greatly helped by reliable prognostic/predictive factors. The importance in identifying resistance is being contributed to by the increased array of possible treatments available for treating resistant advanced disease; the variable clinical course as well as response to any given treatment approach of patients within one staging or grading system, the advances in imaging which are providing increasing promising results/parameters that correlate with grading/outcome/resistance, the increased understanding of the molecular pathogenesis providing promising prognostic markers, all of which can contribute to selecting the best treatment to overcome resistance disease. Several factors have been identified that have prognostic/predictive value for identifying development resistant disease and affecting overall survival (OS)/PFS with various nonsurgical treatments of patients with advanced panNENs. Prognostic factors identified for patients with advanced panNENs for both OS/PFSs include various clinically-related factors (clinical, laboratory/biological markers, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors. Particularly important prognostic factors for the different treatment modalities studies are the recent grading systems. Most prognostic factors for each treatment modality for OS/PFS are not specific for a given treatment option. These advances have generated several controversies and new unanswered questions, particularly those related to their possible role in predicting the possible sequence of different anti-tumor treatments in patients with different presentations. Each of these areas is reviewed in this paper.

Abstract

Purpose: Recent advances in the diagnosis, management and nonsurgical treatment of patients with advanced pancreatic neuroendocrine neoplasms (panNENs) have led to an emerging need for sensitive and useful prognostic factors for predicting responses/survival. Areas covered: The predictive value of a number of reported prognostic factors including clinically-related factors (clinical/laboratory/imaging/treatment-related factors), pathological factors (histological/classification/grading), and molecular factors, on therapeutic outcomes of anti-tumor medical therapies with molecular targeting agents (everolimus/sunitinib/somatostatin analogues), chemotherapy, radiological therapy with peptide receptor radionuclide therapy, or liver-directed therapies (embolization/chemoembolization/radio-embolization (SIRTs)) are reviewed. Recent findings in each of these areas, as well as remaining controversies and uncertainties, are discussed in detail, particularly from the viewpoint of treatment sequencing. Conclusions: The recent increase in the number of available therapeutic agents for the nonsurgical treatment of patients with advanced panNENs have raised the importance of prognostic factors predictive for therapeutic outcomes of each treatment option. The establishment of sensitive and useful prognostic markers will have a significant impact on optimal treatment selection, as well as in tailoring the therapeutic sequence, and for maximizing the survival benefit of each individual patient. In the paper, the progress in this area, as well as the controversies/uncertainties, are reviewed.

Peptide Receptor Radionuclide Therapy Targeting the Somatostatin Receptor: Basic Principles, Clinical Applications and Optimization Strategies

Simple Summary

Peptide receptor radionuclide therapy (PRRT) is a systemic treatment consisting of the administration of a tumor-targeting radiopharmaceutical into the circulation of a patient. The radiopharmaceutical will bind to a specific peptide receptor leading to tumor-specific binding and retention. This will subsequently cause lethal DNA damage to the tumor cell. The only target that is currently used in widespread clinical practice is the somatostatin receptor, which is overexpressed on a range of tumor cells, including neuroendocrine tumors and neural-crest derived tumors. Academia played an important role in the development of PRRT, which has led to heterogeneous literature over the last two decades, as no standard radiopharmaceutical or regimen has been available for a long time. This review focuses on the basic principles and clinical applications of PRRT, and discusses several PRRT-optimization strategies.

Abstract

Peptide receptor radionuclide therapy (PRRT) consists of the administration of a tumor-targeting radiopharmaceutical into the circulation of a patient. The radiopharmaceutical will bind to a specific peptide receptor leading to tumor-specific binding and retention. The only target that is currently used in clinical practice is the somatostatin receptor (SSTR), which is overexpressed on a range of tumor cells, including neuroendocrine tumors and neural-crest derived tumors. Academia played an important role in the development of PRRT, which has led to heterogeneous literature over the last two decades, as no standard radiopharmaceutical or regimen has been available for a long time. This review provides a summary of the treatment efficacy (e.g., response rates and symptom-relief), impact on patient outcome and toxicity profile of PRRT performed with different generations of SSTR-targeting radiopharmaceuticals, including the landmark randomized-controlled trial NETTER-1. In addition, multiple optimization strategies for PRRT are discussed, i.e., the dose–effect concept, dosimetry, combination therapies (i.e., tandem/duo PRRT, chemoPRRT, targeted molecular therapy, somatostatin analogues and radiosensitizers), new radiopharmaceuticals (i.e., SSTR-antagonists, Evans-blue containing vector molecules and alpha-emitters), administration route (intra-arterial versus intravenous) and response prediction via molecular testing or imaging. The evolution and continuous refinement of PRRT resulted in many lessons for the future development of radionuclide therapy aimed at other targets and tumor types.

Peptide receptor radionuclide therapy with [177Lu]Lu-DOTA-TATE

This continuing education aims to present in a clear and easy-to-understand way, the biology of neuroendocrine tumors (NETs), the characteristics of somatostatin receptors, the selection of patients for radiolabelled peptide therapy (PRRT), the inclusion criteria to benefit from treatment with the minimum possible adverse effects, the administration protocol, follow-up and response evaluation. The functional imaging studies necessary to explore the biology of the tumor and to individualize the treatment are also carried out, and constitute the cornerstone for the development of teragnosis. Clinical trials are being developed to better define the position of PRRT within the broad therapeutic options, and among the future perspectives, there are several lines of research to improve the objective response rate and survival with PRRT, focused on the development of new agonists and somatostatin receptor antagonists, new radionuclides and radiosensitizing combination therapies. In conclusion, PRRT is a great therapeutic, well-tolerated and safe tool with generally mild and self-limited acute side effects, that must be sequenced at the best moment of the evolution of the disease of patients with NET. Candidate patients for PRRT should always be evaluated by a multidisciplinary clinical committee.

What Are the Place and Modalities of Surgical Management for Pancreatic Neuroendocrine Neoplasms? A Narrative Review

Pancreatic neuroendocrine neoplasms (panNENs) are a heterogeneous group of tumors derived from cells with neuroendocrine differentiation. They are considered malignant by default. However, their outcomes are variable depending on their presentation in the onset of hereditary syndromes, hormonal secretion, grading, and extension. Therefore, although surgical treatment has long been suggested as the only treatment of pancreatic neuroendocrine neoplasms, its modalities are an evolving landscape. For selected patients (small, localized, non-functional panNENs), a "wait and see" strategy is suggested, as it is in the setting of multiple neuroendocrine neoplasia type 1, but the accurate size cut-off remains to be established. Parenchyma-sparring pancreatectomy, aiming to limit pancreatic insufficiency, are also emerging procedures, which place beyond the treatment of insulinomas and small non-functional panNENs (in association with lymph node picking) remains to be clarified. Furthermore, giving the fact that the liver is generally the only metastatic site, surgery keeps a place of choice alongside medical therapies in the treatment of metastatic disease, but its modalities and extensions are still a matter of debate. This narrative review aims to describe the current recommended surgical management for pancreatic NENs and controversies in light of the actual recommendations and recent literature.

A combination of surgery, theranostics, and liquid biopsy - a personalised oncologic approach to treatment of patients with advanced metastatic neuroendocrine neoplasms

Rationale: Neuroendocrine neoplasia (NEN) of small bowel (SBNEN) frequently present with metastatic disease. Theranostics (molecular imaging followed by targeting therapy) allow for personalised medicine. Liquid biopsies enable precise identification of residual disease and real-time monitoring of therapeutic response. Our aim was to determine the clinical utility of a combination of surgery, theranostics, and a multigene blood measurement in metastasised SBNEN. Methods: Inclusion criteria were SBNEN, G1/G2 NEN, initial tumour diagnosis, stage IV NEN, positivity on 68Ga somatostatin analogue PET/CT, eligible for surgery, and 177Lu peptide receptor radionuclide therapy (PRRT). Blood samples for NETest were collected longitudinally. Progression-free survival (PFS) and overall survival (OS) were calculated. NETest results were assessed prior to surgery and during clinical follow-up. Results: A surgical cohort of 39 SBNEN patients met eligibility criteria. Thirty-two patients underwent ileal resection and 7 right hemicolectomy. The mean number of 177Lu PRRT cycles was 4. Mortality was nil. Surgical morbidity was 10.3%. Transient grade 1/2 toxicity occurred in 41% (PRRT). NETest scores (n=9 patients) decreased in 100% following treatment and correlated with diminished tumour volume and disease stabilization following surgery and PRRT. Median follow-up: 78 months. Median PFS and OS: 42.7 and 110 months, respectively. Progression-free survival at 1-, 3-, and 5-years was 79.4%, 57.1% and 40.5%, respectively. Overall survival at 1-, 3-, and 5-years was 97.4%, 97.4%, and 94.1%, respectively. Conclusions: Surgery combined with 177Lu PRRT is safe and provides favourable PFS and OS in selected patients with advanced SBNEN. Liquid biopsy (NETest) has the potential to accurately delineate disease status.

Strategies Towards Improving Clinical Outcomes of Peptide Receptor Radionuclide Therapy

Purpose of Review

Peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu-DOTA⁰,Tyr³] octreotate is an effective and safe second- or third-line treatment option for patients with low-grade advanced gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN). In this review, we will focus on possible extensions of the current use of PRRT and on new approaches which could further improve its treatment efficacy and safety.

Recent Findings

Promising results were published regarding PRRT in other NENs, including lung NENs or high-grade NENs, and applying PRRT as neoadjuvant or salvage therapy. Furthermore, a diversity of strategic approaches, including dosimetry, somatostatin receptor antagonists, somatostatin receptor upregulation, radiosensitization, different radionuclides, albumin binding, alternative renal protection, and liver-directed therapy in combination with PRRT, have the potential to improve the outcome of PRRT. Also, novel biomarkers are presented that could predict response to PRRT.

Summary

Multiple preclinical and early clinical studies have shown encouraging potential to advance the clinical outcome of PRRT in NEN patients. However, at this moment, most of these strategies have not yet reached the clinical setting of randomized phase III trials.

Surgical feasibility, Determinants and overall Efficacy assessment of Neoadjuvant PRRT with 177Lu-DOTATATE for Locally Advanced Unresectable Gastroenteropancreatic Neuroendocrine Tumors

OBJECTIVE: The aim of the study was to assess ¹⁷⁷Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in neoadjuvant setting in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). In addition, we also evaluated the variables associated with resectability of the primary following PRRT. MATERIALS AND METHODS: A total of 57 GEP-NETs with unresectable primary due to vascular involvement as defined using the National Comprehensive Cancer Network (NCCN) criteria given for pancreatic ductal adenocarcinoma (PDAC), who underwent ¹⁷⁷Lu-DOTATATE without any prior surgery were included in this study. GEP-NETs were divided into two groups: Group1-without liver metastases (n = 23 patients) and Group2- with potentially resectable liver metastases (n = 34 patients). ¹⁷⁷Lu-DOTATATE was administered with mixed amino acid-based renal protection with dose of 7.4 GBq (200 mCi) per cycle. Evaluation of surgical resectability following PRRT was done by using tri-phasic computed tomography (CT) imaging. Overall PRRT response was evaluated under four broad categories. The Kaplan-Meier product-limit method was used to calculate progression free survival (PFS) and overall survival (OS). Associations between variables and resectable primary after PRRT were analyzed by using Chi-square test at significant P value less than 0.05. RESULTS: Following ¹⁷⁷Lu-DOTATATE, unresectable primary became resectable in 15 out of 57 (26.3%) patients {7 patients in group-1 and 8 patients in group-2}. Response (complete response and partial response) to PRRT was seen in 48 patients (84%), 23 patients (40%), 18 patients (31%) and 23 patients (40%) on symptomatic, biochemical, molecular imaging and anatomical imaging response evaluation criteria respectively. Estimated rates of PFS were 95% and 90% at 2 years in group1 and group2 patients respectively. The 2-years OS of combined both groups was 92.1%. Higher rate of resectable primary following PRRT was found in duodenal NET, GEP-NETs with absent regional lymph node involvement, size of primary<5cm, size of liver lesions ≤1.5 cm, number of liver lesions ≤3 and FDG uptake(SUV_max<5 in primary tumor) with significant P value. CONCLUSION: Thus, unresectable primary converted could be into resectable in a moderate fraction of GEP-NETs following ¹⁷⁷Lu-DOTATATE, signifying that neoadjuvant PRRT could be considered in GEP-NETs patients with unresectable primary due to vascular involvement with or without liver metastases. Effective control of symptoms with favorable morphological and functional imaging response and durable PFS and OS following ¹⁷⁷Lu-DOTATATE PRRT were important observation in our study, which may lead to less morbidity and mortality in these patients.

The State of Peptide Receptor Radionuclide Therapy and Its Sequencing among Current Therapeutic Options for Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are the most common form of neuroendocrine neoplasia, but there is no current consensus for the sequencing of approved therapies, particularly with respect to peptide receptor radionuclide therapy (PRRT). This comprehensive review evaluates the data supporting approved therapies for GEP-NETs and recommendations for therapeutic sequencing with a focus on how PRRT currently fits within sequencing algorithms. The current recommendations for PRRT sequencing restrict its use to metastatic, inoperable, progressive midgut NETs; however, this may change with emerging data to suggest that PRRT might be beneficial as neoadjuvant therapy for inoperable tumors, is more tolerable than other treatment modalities following first-line standard dose somatostatin analogs, and can be used as salvage therapy after disease relapse following prior successful cycles of PRRT. PRRT has also been shown to reduce tumor burden, improve quality of life, and prolong the time to disease progression in a broad spectrum of patients with GEP-NETs. As the various potential benefits of PRRT in GEP-NET therapy continues to expand, it is necessary to review and critically evaluate our treatment algorithms for GEP-NETs.

Neoadjuvant Therapy for Neuroendocrine Neoplasms: Recent Progresses and Future Approaches

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors, their treatment being challenging and requiring a multidisciplinary approach. Though the only curative treatment is surgery, up to 50% of patients are diagnosed with metastatic disease. In the last years, neoadjuvant chemo(radio)therapy has become part of the standard of care in the treatment of different cancer types. However, evidence of its efficacy and safety in NEN patients has not yet been confirmed in the literature. The aim of the present review is to perform an extensive review of the scientific evidence for neoadjuvant therapy in patients with gastroenteropancreatic and thoracic NENs.

Peptide receptor radionuclide therapy as a two-step strategy for initially unresectable liver disease from neuroendocrine tumors: a single-center experience

PURPOSE

In this study, we describe our experience with peptide receptor radionuclide therapy (PRRT) for initially unresectable liver disease as a two-steps therapeutic strategy, first in neoadjuvant intention before surgery and then later on in case of disease relapse.

METHODS

We performed a retrospective evaluation of four cases of unresectable liver metastases of NET of different origins treated with neoadjuvant Lu-177-DotaTATE for conversion into resectability first and as rechallenging treatment after disease relapse.

RESULTS

After treatment with Lu-177-DotaTAE, resectability was reached in three of four cases. In one case, SIRT was additionally performed preoperatively. Relapse occurred in three of four cases after 32, 34, and 37 months, respectively, and was managed with Re-PRRT-treatment.

CONCLUSION

Although more data are needed, our retrospective study suggests that treatment with Lu-177-DotaTATE is an important adjunct to surgery not only in neoadjuvant intention but also for treating disease relapse. A register study might deliver more evidence for supporting this strategy.

High Interobserver Agreement for the Standardized Reporting System SSTR-RADS 1.0 on Somatostatin Receptor PET/CT

Recently, a standardized framework system for interpreting somatostatin receptor (SSTR)-targeted PET/CT, termed the SSTR reporting and data system (RADS) 1.0, was introduced, providing reliable standards and criteria for SSTR-targeted imaging. We determined the interobserver reliability of SSTR-RADS for interpretation of ⁶⁸Ga-DOTATOC PET/CT scans in a multicentric, randomized setting. Methods: A set of 51 randomized ⁶⁸Ga-DOTATOC PET/CT scans was independently assessed by 4 masked readers with different levels of experience (2 experienced readers and 2 inexperienced readers) trained on the SSTR-RADS 1.0 criteria (based on a 5-point scale from 1 [definitively benign] to 5 [high certainty that neuroendocrine neoplasia is present]). For each scan, SSTR-RADS scores were assigned to a maximum of 5 target lesions (TLs). An overall scan impression based on SSTR-RADS was indicated, and interobserver agreement rates on a TL-based, on an organ-based, and on an overall SSTR-RADS score-based level were computed. The readers were also asked to decide whether peptide receptor radionuclide therapy (PRRT) should be considered on the basis of the assigned RADS scores. Results: Among the selected TLs, 153 were chosen by at least 2 readers (all 4 readers selected the same TLs in 58 of 153 [37.9%] instances). The interobserver agreement for SSTR-RADS scoring among identical TLs was good (intraclass correlation coefficient [ICC] ≥ 0.73 for 4, 3, and 2 identical TLs). For lymph node and liver lesions, excellent interobserver agreement rates were derived (ICC, 0.91 and 0.77, respectively). Moreover, the interobserver agreement for an overall scan impression based on SSTR-RADS was excellent (ICC, 0.88). The SSTR-RADS-based decision to use PRRT also demonstrated excellent agreement, with an ICC of 0.80. No significant differences between experienced and inexperienced readers for an overall scan impression and TL-based SSTR-RADS scoring were observed (P ≥ 0.18), thereby suggesting that SSTR-RADS seems to be readily applicable even for less experienced readers. Conclusion: SSTR-RADS-guided assessment demonstrated a high concordance rate, even among readers with different levels of experience, supporting the adoption of SSTR-RADS for trials, clinical routine, or outcome studies.

One decade of 'Bench-to-Bedside' peptide receptor radionuclide therapy with indigenous [177Lu]Lu-DOTATATE obtained through 'Direct' neutron activation route: lessons learnt including practice evolution in an Indian setting

The present treatise chronicles one decade of experience pertaining to clinical PRRT services in a large-volume tertiary cancer care centre in India delivering over 4,000 therapies, an exemplar of successful PRRT programme employing indigenous 177Lutetium production and resources. For the purpose of systematic discussion, we have sub-divided the communication into 3 specific parts: (a) Radiopharmaceutical aspects that describes 177Lutetium production through 'Direct' Neutron Activation Route and the subsequent radiolabeling procedures, (b) The specific clinical nuances and finer learning points (apart from the routine standard procedure) based upon clinical experience and how it has undergone practice evolution in our setting and (c) Dosimetry results with this indigenous product and radiation safety/health physics aspects involved in PRRT services. Initiated in 2010 at our centre, the PRRT programme is a perfect example of affordable quality health care delivery, with indigenous production of the radionuclide (177Lu) in the reactor and subsequent radiolabeling of the radiopharmaceutical ([177Lu]Lu-DOTATATE) at the hospital radiopharmacy unit of the centre, which enabled catering to the needs of a large number of patients of progressive, metastatic and advanced Neuroendocrine Neoplasms (NENs) and related malignancies.

Systemic Treatment Selection for Patients with Advanced Pancreatic Neuroendocrine Tumours (PanNETs)

Pancreatic neuroendocrine tumours (PanNETs) are rare diseases and a good example of how research is not only feasible, but also of crucial importance in the scenario of rare tumours. Many clinical trials have been performed over the past two decades expanding therapeutic options for patients with advanced PanNETs. Adequate management relies on optimal selection of treatment, which may be challenging for clinicians due to the fact that multiple options of therapy are currently available. A number of therapies already exist, which are supported by data from phase III studies, including somatostatin analogues and targeted therapies (sunitinib and everolimus). In addition, chemotherapy remains an option, with temozolomide and capecitabine being one of the most popular doublets to use. Peptide receptor radionuclide therapy was successfully implemented in patients with well-differentiated gastro-entero-pancreatic neuroendocrine tumours, but with certain questions waiting to be solved for the management of PanNETs. Finally, the role of immunotherapy is still poorly understood. In this review, the data supporting current systemic treatment options for locally advanced or metastatic PanNETs are summarized. Strategies for treatment selection in patients with PanNETs based on patient, disease, or drug characteristics is provided, as well as a summary of current evidence on prognostic and predictive biomarkers. Future perspectives are discussed, focusing on current and forthcoming challenges and unmet needs of patients with these rare tumours.

Management of Ileal Neuroendocrine Tumors with Liver Metastases

PURPOSE

Assessment of treating metastatic ileal neuroendocrine tumors (NETs) with complete resection of primary tumor, nodal and liver metastases, plus administration of long-acting somatostatin analogues (SSAs).

METHODS

A prospective database was queried for patients with ileal or pancreatic NETs with pathology-confirmed liver metastases and tumor somatostatin receptors. Patients did not have MEN-1 and had no previous treatment. The impacts of SSA treatment on the primary outcome of survival and secondary outcome of progression-free survival were assessed with Kaplan-Meier analysis. Log rank test was used to compare overall and progression-free survival among groups.

RESULTS

Seventeen ileal NET patients and 36 pancreatic NET patients who underwent surgical resection between 2001 and 2018, who had pathology-confirmed liver metastases and confirmed tumor somatostatin receptors, did not have MEN-1, and had no previous treatment were identified. Median follow-up for patients with ileal NETs was 80 months (range 0-197 months) and 32 months (range 1-182 months) for pancreatic NETs. Five-year survival was 93% and 72% for ileal and pancreatic NET, respectively. Progression-free 5-year survival was 70% and 36% for ileal and pancreatic NET, respectively. Overall 5-year survival for pNETs was greater in those patients treated with SSA (79%) compared to those who underwent surgery alone (34%, p < 0.01). The average ECOG score was low for surviving patients with ileal (0.15) and pancreatic NET (0.73) indicating a good quality of life.

CONCLUSIONS

Resection of primary lymph node and liver metastatic ileal or pancreatic NETs followed with continued SSAs is associated with an excellent progression-free and overall survival and minimal side effects.

Histopathological and Immunophenotypic Changes of Pancreatic Neuroendocrine Tumors after Neoadjuvant Peptide Receptor Radionuclide Therapy (PRRT)

Peptide Receptor Radionuclide Therapy (PRRT) is an emerging therapeutic option for pancreatic neuroendocrine tumors (PanNETs). A possible role for PRRT as a neoadjuvant agent is still largely undetermined, explored only in case reports or small case series. Likewise, the histopathological and immunophenotypic changes induced by PRRT are poorly characterized. In the present study, 24 patients who underwent neoadjuvant PRRT on the basis of their disease's characteristics were retrospectively matched with 24 patients who underwent upfront surgery. A comprehensive morphological and immunohistochemical evaluation was conducted to identify the differences in the two groups. The most significant findings were that the total percentage of stroma increased significantly in patients who underwent PRRT (p < 0.0001) and the characteristics of the stroma were different in the two groups. The somatostatin receptors type 2A (SSTR2A) were retained in most patients (87%) after PRRT. The density of CD163+ M2-polarized macrophages was greater in the PRRT group (p = 0.022), and M2-polarized macrophages tended to assume an epithelioid morphology (p = 0.043). In the neoadjuvant PRRT group, none of the histological parameters considered were associated with progression-free survival (PFS). Neoadjuvant PRRT in PanNETs is associated with reduced tumor diameter, an increased percentage of stroma, preserved SSTR2A expression in most of the cases, and an increased CD163+ M2-polarized macrophages density.

Liver transplantation in the treatment of unresectable hepatic metastasis from neuroendocrine tumors

Neuroendocrine tumors (NET) are rare neoplasms with generally indolent growth behavior. The liver is the most common site of NET metastasis. The NET metastatic spread to the liver are usually multiple tumors involving bilateral hemilivers. For patients with isolated NET metastasis to the liver, a complete extirpation (R0) resection of both the primary NET and liver metastasis provide the best chance of tumor recurrence-free patient survival. Orthotopic liver transplantation (OLT) presents a viable treatment option for patients with unresectable liver metastasis from NET. Post-OLT outcomes for the patients of NET with liver metastasis (5-year overall survival rate 47-71%) are comparable to those for other indications. However, the high rate of recurrence after OLT (31-57%) remains a clinical obstacle. As such, it is imperative to consider each patient individually and identify prognostic factors that would impact post-OLT outcomes. This article focuses on the role of OLT in the definitive treatment of metastatic liver NET, review patient selection criteria predictive of survival outcomes and post-OLT outcomes for patients.

Response rates in metastatic neuroendocrine tumors receiving peptide receptor radionuclide therapy and implications for future treatment strategies

BACKGROUND

Peptide receptor radionuclide therapy is a targeted therapy used to treat unresectable somatostatin receptor-positive neuroendocrine tumors. The objective of this study was to evaluate response rates among neuroendocrine tumors of different primaries and identify factors relevant to future treatment strategies.

METHODS

We retrospectively reviewed patients who received peptide receptor radionuclide therapy for neuroendocrine tumors from 2018 to 2019 at our institution. Patients were assessed with computed tomography/magnetic resonance imaging and ⁶⁸Ga-DOTATATE-positron emission tomography before and after 2 or 4 cycles of peptide receptor radionuclide therapy. Tumor response was evaluated by RECIST 1.1. Statistics included multinomial logistic regression models and Fisher exact test.

RESULTS

Twenty-seven patients underwent 92 cycles of peptide receptor radionuclide therapy: pancreas (n = 11), small bowel (n = 7), and other (n = 9) neuroendocrine tumors. Overall, 30% (8 of 27) had partial response, 59% (16 of 27) stable disease, and 11% (3 of 27) progressed. Pancreatic neuroendocrine tumors responded differently from small bowel neuroendocrine tumors regardless of cycle number (P = .01). The majority of pancreatic neuroendocrine tumors (6 of 11) had partial response to peptide receptor radionuclide therapy, while all small bowel neuroendocrine tumors had stable disease. Pancreatic neuroendocrine tumors stable after 2 cycles were more likely to respond to additional cycles versus other neuroendocrine tumors (probability: 60% vs 11%).

CONCLUSION

Patients with unresectable advanced or metastatic pancreatic neuroendocrine tumors may benefit from a full course of peptide receptor radionuclide therapy, whereas other neuroendocrine tumors appear less likely to respond. Large prospective studies are needed to confirm these findings.

[Treatment of colorectal and non-colorectal liver metastases: rationale for neoadjuvant therapeutic concepts]

BACKGROUND

Liver metastases represent the most common secondary malignant liver disease. Data regarding the incidence of colorectal and non-colorectal liver metastases are rare due to insufficient documentation in a register. Results regarding neoadjuvant therapy are limited and mostly from retrospective analyses.

OBJECTIVE

A summary and rating of the rationale for neoadjuvant therapeutic concepts for colorectal and non-colorectal liver metastases were performed.

MATERIAL UND METHODS

The analysis was based on European and American guidelines and included publications in both German and English languages. The results and recommendations were summarized and a review based on the literature is given.

RESULTS

Neoadjuvant treatment of liver metastases is performed with heterogeneous intentions. The selection of biologically favorable tumors as well as the conversion of primarily non-operable into resectable metastases of the liver are classical reasons for neoadjuvant treatment. The rationale for neoadjuvant treatment of colorectal and especially for non-colorectal liver metastases cannot be answered in a consistently coherent way with respect to the current status quo of the literature and guidelines. The creation of treatment strategies in clinical settings follows criteria, such as patterns of metastases, complexity of the resection and biological factors (metachronous/synchronous metastases, prognostic factors).

CONCLUSION

Neoadjuvant treatment in the context of conversion therapy is the standard procedure for metastasized colorectal cancer. The biological selection of favorable tumors as the basis for neoadjuvant treatment of resectable lesions is not a consistently used standard for colorectal cancer. Non-colorectal liver metastases are resected only as part of individual concepts.

The North American Neuroendocrine Tumor Society Consensus Paper on the Surgical Management of Pancreatic Neuroendocrine Tumors

This manuscript is the result of the North American Neuroendocrine Tumor Society consensus conference on the surgical management of pancreatic neuroendocrine tumors from July 19 to 20, 2018. The group reviewed a series of questions of specific interest to surgeons taking care of patients with pancreatic neuroendocrine tumors, and for each, the available literature was reviewed. What follows are these reviews for each question followed by recommendations of the panel.

The Role of Perioperative Systemic Therapy in Localized Pancreatic Neuroendocrine Neoplasms

BACKGROUND

The role of perioperative systemic therapy (PST) in the management of localized pancreatic neuroendocrine neoplasms (PanNEN) is unclear.

OBJECTIVES

We aimed to evaluate the benefit of PST compared to surgery alone (SA) in patients with localized PanNEN.

METHOD

We selected patients with stages I-III PanNEN who underwent curative-intent surgical resection in National Cancer Database from 2006 to 2014. Patients who had both PST and surgical resection were matched with patients who received SA by propensity score at 1-to-1 ratio with nearest neighbor method.

RESULTS

Four thousand eight hundred and ninety-two patients were included in this study with median age of 60 years. Factors associated with significant more use of PST compared to SA included age <65 years, community medical facilities, grade 3 tumor, tumor in the pancreatic head, T34 tumor, and N1 tumor. Three hundred and one PST patients were matched with 301 SA patients. In the matched cohort, the PST group had significantly shorter overall survival (OS) compared to the SA group (median overall both not reached, p = 0.037). This finding was confirmed by multivariable Cox proportional hazards regression in the original cohort (hazard ratio [HR] 1.45, 95% CI 1.11-1.89, p = 0.006). Subgroup analyses showed that adjuvant therapy was not associated with improved OS in grades 1-2 PanNEN (HR 2.03, 95% CI 1.31-3.16, p = 0.002).

CONCLUSIONS

PST stratified by grade and neoadjuvant or adjuvant therapy compared to SA was not associated with improved OS in patients with localized PanNEN. PST for localized PanNEN should be used with caution until prospective data are available.

Systemic treatment for lung carcinoids: from bench to bedside

In the huge spectrum of lung neuroendocrine neoplasms, typical and atypical carcinoids should be considered as a separate biological entity from poorly differentiated forms, harboring peculiar molecular alterations. Despite their indolent behavior, lung carcinoids correlate with a worse survival. To date, only limited therapeutic options are available and novel drugs are strongly needed. In this work, we extensively reviewed scientific literature exploring available therapeutic options, new molecular targets and future perspectives in the management of well differentiated neoplasms of bronchopulmonary tree. Systemic therapy represents the main option in advanced and unresectable disease; accepted choices are somatostatin analogs, peptide receptor radionuclide therapy, everolimus and chemotherapy. To date, an univocal treatment strategy has not been identified yet, thus tailored therapeutic algorithms should consider treatment efficacy as well as safety profiles. Several molecular alterations found in carcinoid tumors might act as molecular targets leading to development of new therapeutic options. Further studies are necessary to identify new potential “druggable” molecular targets in the selected subset of low-grade lung carcinoids. Furthermore, evaluating the available therapies in more homogeneous population might improve their efficacy through a perfect tailoring of treatment options.

Unmet Needs in Functional and Nonfunctional Pancreatic Neuroendocrine Neoplasms

Recently, the European Neuroendocrine Tumor Society (ENETS) held working sessions composed of members of the advisory board and other neuroendocrine neoplasm (NEN) experts to attempt to identify unmet needs in NENs in different locations or with advanced/poorly differentiated NENs. This report briefly summarizes the main proposed areas of unmet needs in patients with functional and nonfunctional pancreatic NENs.

Surgical Approaches to the Management of Neuroendocrine Liver Metastases

Surgical approaches to hepatic metastases occupy an important role in the management of patients with neuroendocrine neoplasms and may have curative or palliative intentions. Resection of hepatic disease with curative intent is the only modality offering potential cure for patients with liver metastases; however, only a minority of patients are eligible. Regardless of resection margin, disease recurrence almost invariably occurs and novel adjuvant/neoadjuvant therapies are mandated to be included within multimodal treatment concepts. Liver transplantation in meticulously selected patients may be associated with excellent outcomes, but unfortunately demands on donated organs limit the wider utilization of this approach.

Preoperative Fluorouracil, Doxorubicin, and Streptozocin for the Treatment of Pancreatic Neuroendocrine Liver Metastases

INTRODUCTION

While preoperative chemotherapy is frequently utilized before resection of non-neuroendocrine liver metastases, patients with resectable neuroendocrine liver metastases typically undergo surgery first. FAS is a cytotoxic chemotherapy regimen that is associated with substantial response rates in locally advanced and metastatic pancreatic neuroendocrine tumors.

METHODS

All patients who underwent R0/R1 resection of pancreatic neuroendocrine liver metastases at a single institution between 1998 and 2015 were included. The outcomes of patients treated with preoperative FAS were compared with those of patients who were not.

RESULTS

Of the 67 patients included, 27 (40.3%) received preoperative FAS, whereas 40 (59.7%) did not. Despite being associated with higher rates of synchronous disease, lymph node metastases, and larger tumor size, patients who received preoperative FAS had similar overall survival [overall survival (OS), 108.2 months (95% confidence interval (CI) 78.0-136.0) vs. 107.0 months (95% CI 78.0-136.0), p = 0.64] and recurrence-free survival [RFS, 25.1 months (95% CI 23.2-27.0) vs. 18.0 months (95% CI 13.8-22.2), p = 0.16] as patients who did not. Among patients who presented with synchronous liver metastases (n = 46), the median OS [97.3 months (95% CI 65.9-128.6) vs. 65.0 months (95% CI 28.1-101.9), p = 0.001] and RFS [24.8 months (95% CI 22.6-26.9) vs. 12.1 months (2.2-22.0), p = 0.003] were significantly greater among patients who received preoperative FAS compared with those who did not.

CONCLUSIONS

The use of FAS before liver resection is associated with improved OS compared with surgery alone among patients with advanced synchronous pancreatic neuroendocrine liver metastases.

Peptide Receptor Radionuclide Therapy and the Treatment of Gastroentero-pancreatic Neuroendocrine Tumors: Current Findings and Future Perspectives

Purpose and Methods

Patients with inoperable and metastasized neuroendocrine tumors (NETs), particularly those with grades 1 and 2, usually receive treatment with somatostatin analogues (SSAs). Peptide receptor radionuclide therapy (PRRT) has gained momentum over the past two decades in patients who progress on SSAs. 177Lu-DOTATATE is currently the most widely used radiopeptide for PRRT. We reviewed the recent evidence on PRRT and the treatment of gastroentero-pancreatic neuroendocrine tumors (GEP-NETs).

Results

¹⁷⁷Lu-DOTATATE can be used as neoadjuvant treatment in patients with inoperable GEP-NETs, who might be candidate for surgery after treatment and as adjuvant therapy after surgical intervention. Combination treatments of PRRT with chemotherapy or targeted agents as well as combinations of radionuclides in patients with NETs have been explored over the last few years. The majority of patients with NETs experience partial response or have disease stabilization, a small percentage has complete response, while some 30% of patients, however, will have disease progression. The safety and efficacy of retreatment with extra cycles of PRRT as salvage therapy have been evaluated in small retrospective series.

Conclusion

Overall, there is evidence that disease control and quality of life improve significantly after 117Lu PRRT therapy. Clinical trials on this therapy are scarce, and there is a need for further studies to establish proper management guidelines.

Surgical management of neuroendocrine tumor-associated liver metastases: a review

Liver metastasis is common among patients who suffer from neuroendocrine tumors (NETs). Radical surgery is the standard treatment whenever possible but there is still controversies concerning the treatment strategies such as resection of the primary, role of debulking surgery, liver transplantation (LT) and neoadjuvant or adjuvant therapies. This article aims to review the current evidence available, together with some latest updates, focusing on the surgical management.

Everolimus in Combination with Octreotide Long-Acting Repeatable in a First-Line Setting for Patients with Neuroendocrine Tumors: A 5-Year Update

BACKGROUND

We previously presented data of this multicentric, phase II study showing that everolimus plus octreotide long-acting repeatable (LAR) for advanced neuroendocrine neoplasms (NENs), in the first line setting, is an active and safe treatment. We now present updated data at 5 years.

METHODS

Patients with advanced well-differentiated, previously untreated neuroendocrine tumors of the gastroenteropancreatic tract and of the lung received octreotide LAR 30 mg plus everolimus 10 mg/day. The primary endpoint was the objective response rate (ORR). We performed an analysis of "long responder" patients and of time to progression (TTP) and overall survival (OS) at 5 years.

RESULTS

Fifty patients were enrolled; the primary tumor site was: pancreas (14 patients), lung (11 patients), ileum (9 patients), jejunum/duodenum (2 patients), and unknown (14 patients). Seventeen (34%) of these patients have received treatment for more than 2 years. The median exposure to study drugs was 519.5 days (range 48-2,024). Currently 3 patients are still in treatment. The ORR (partial response + complete response) was 18% (95% confidence interval [CI] 7.4-28.6): complete response 1 patient (2%), partial response 8 patients (16%), stable disease 37 patients (74%). The median TTP was 33.6 months (95% CI 18.7-41.2) and the median OS was 61.0 months (95% CI 49.8-not reached).

CONCLUSION

In this update of clinical outcome at 5-year follow-up, everolimus plus octreotide has been shown to be active in advanced NENs. The current analysis showed a further prolongation of TTP and a long exposure to the study drug without major side effects in the long term.

Peptide receptor radionuclide therapy as neoadjuvant therapy for resectable or potentially resectable pancreatic neuroendocrine neoplasms

BACKGROUND

Peptide receptor radionuclide therapy is a valid therapeutic option for pancreatic neuroendocrine neoplasms. The aim of this study was to describe an initial experience with the use of peptide receptor radionuclide therapy as a neoadjuvant agent for resectable or potentially resectable pancreatic neuroendocrine neoplasms.

METHODS

The postoperative outcomes of 23 patients with resectable or potentially resectable pancreatic neuroendocrine neoplasms at high risk of recurrence who underwent neoadjuvant peptide receptor radionuclide therapy (peptide receptor radionuclide therapy group) were compared with 23 patients who underwent upfront surgical operation (upfront surgery group). Patients were matched for tumor size, grade, and stage. Median follow-up was 61 months.

RESULTS

The size (median greatest width) of the primary pancreatic neuroendocrine neoplasms decreased after neoadjuvant peptide receptor radionuclide therapy (59 to 50 mm; P=.047). There were no differences in intraoperative and postoperative outcomes and there were no operative deaths, but the risk of developing a pancreatic fistula tended to be less in the peptide receptor radionuclide therapy group when compared to the upfront surgery group (0/23 vs 4/23; P < .02). The incidence of nodal metastases at the time of resection was also less in the peptide receptor radionuclide therapy group (n= 9/23 vs 17/23; P<.02). Neither median disease-specific survival (not reached in either group; P=.411) nor progression-free survival (52 vs 37 months; P>.2) differed between groups, but progression-free survival in the 31 patients who had an R0 resection seemed to be greater in the 15 patients in the peptide receptor radionuclide therapy group versus 16 patients the upfront group (median progression-free survival not reached vs 36 months; P<.05).

CONCLUSION

Neoadjuvant peptide receptor radionuclide therapy for resectable or potentially resectable pancreatic neuroendocrine neoplasms in patients with high-risk features of recurrence seems to be beneficial, but well-designed and much larger prospective trials are needed to confirm the safety and the oncologic value of this approach.

Peptide Receptor Radionuclide Therapy With 177Lu-Octreotate in Patients With Somatostatin Receptor Expressing Neuroendocrine Tumors: Six Years' Assessment

OBJECTIVES

Peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogues is a promising treatment for patients with inoperable, well to moderately differentiated metastatic neuroendocrine tumors (NETs). In continuation of our novel study with the radionuclide lutetium Lu, we now present further results of Lu DOTATATE therapy in managing NETs and other somatostatin receptor-expressing tumors in a larger and more diverse patient group.

PATIENTS AND METHODS

One hundred forty-four consecutive patients (85 men and 59 women; age range, 11-87 years; mean age, 58.5 years) with histologically confirmed NET were enrolled. One hundred forty-three patients received at least 1 cycle of treatment. Among them, 132 were deemed evaluable by having at least 1 cycle of treatment and a posttreatment MRI or CT scan for assessment based on modified Response Evaluation Criteria in Solid Tumors. Response to therapy was evaluated in terms of progression-free survival, overall survival, as well as radiologic, biochemical, and clinical responses. Further, analysis of symptoms was reviewed during therapy and also in subsequent follow-ups for safety evaluation. Renal, gastrointestinal (GI), hepatic, and hematological adverse events were evaluated using National Cancer Institute common toxicities criteria V4.03, through full blood panels, as well as consultation with patients for any symptoms and/or adverse events.

RESULTS

As of July 2016, median progression-free survival was about to be reached. Of 28 patients who have completed Lu DOTATATE therapy (completion of 4 or more cycles of treatment and all designated follow-ups), no patient showed complete response (CR), 8 patients (28.57%) showed partial response (PR), 16 patients (57.14%) showed stable disease (SD), and progressive disease (PD) was observed in 4 patients (14.28%). The objective response rate (CR + PR) of this group was 28.57% (n = 8) with a cumulative disease control (CR + PR + SD) of 85.71% (n = 24).Among 132 evaluable patients, assessment of treatment response using modified Response Evaluation Criteria in Solid Tumors criteria revealed CR in none of the patients, PR in 12 patients (9.09%), SD in 66 patients (50%), whereas PD, which included patients who passed away, was observed in 54 patients (40.90%), yielding an objective response rate of 9.09% (n = 12) and a cumulative disease control rate of 59.09% (n = 78).Symptoms including abdominal pain, diarrhea, flushing, and fatigue improved in over 50% of the patients, whereas weight loss improved in 28.26% of the patients. No grade 3 or grade 4 renal toxicities were found, though eleven grade 3 and five grade 4 hematological as well as three grade 3 hepatotoxicities were reported. Grade 3 hematotoxicity lasted an average of 2.7 months, and grade 4 lasted for only 0.9 months, whereas grade 3 hepatotoxicity lasted an average of 3.1 months.

CONCLUSIONS

Lu-octreotate peptide receptor radionuclide therapy has shown promising potential as a safe and effective targeted therapy in inoperable, well to moderately differentiated metastatic neuroendocrine cancers. The results of the multicenter randomized clinical trial conducted in United States and Europe are concordant with current study.

Theranostics of Neuroendocrine Tumors

Somatostatin receptor positron emission tomography/computed tomography using ⁶⁸Ga-labeled somatostatin analogs is the mainstay for the evaluation of receptor status in neuroendocrine tumors (NETs). This translates towards better therapy options, with increasing evidence of peptide receptor radionuclide therapy (PRRT) as the treatment of choice for advanced or progressive NETs. There are benefits in progression-free and overall survival as well as a significant improvement in clinical condition. In patients with progressive NETs, fractionated, personalized PRRT results in good therapeutic responses with no significant severe hematological and/or renal toxicity, thus improving quality of life.

Radionuclide Therapy for Neuroendocrine Tumors

Peptide receptor radionuclide therapy (PRRT) is a form of systemic radiotherapy that allows targeted delivery of radionuclides to tumor cells expressing high levels of somatostatin receptors. The two radiopeptides most commonly used for PRRT, ⁹⁰Y-DOTATOC and ¹⁷⁷Lu-DOTATATE, have been successfully employed for more than a decade for the treatment of advanced neuroendocrine tumors (NETs). Recently, the phase III, randomized NETTER-1 trial has compared ¹⁷⁷Lu-DOTATATE versus high-dose octreotide LAR in patients with progressive, metastatic midgut NETs, demonstrating exceptional tolerability and efficacy. This review summarizes recent developments in the field of radionuclide therapy for gastroenteropancreatic and lung NETs and considers possible strategies to further enhance its clinical efficacy.

Neoadjuvant peptide receptor radionuclide therapy and modified multivisceral transplantation for an advanced small intestinal neuroendocrine neoplasm: an updated case report

Small intestinal neuroendocrine neoplasms (SI-NEN) frequently metastasise to regional lymph nodes, and surgery is the mainstay of therapy for such patients. However, despite the possible use of advanced surgical techniques, the resection of both primary and locoregional diseases is not always attainable. Intestinal and multivisceral transplantation has been performed in a small number of patients with conventionally nonresectable, slow-growing tumours threatening the mesenteric root but has remained controversial. The use of donor skin in “sentinel flaps” in transplantation theoretically offers advantages in tailoring immunosuppression and monitoring for rejection. We represent (with extended follow-up) the first case of a patient with inoperable extensive mesenteric metastases from SI-NEN, who underwent neoadjuvant peptide receptor radionuclide therapy before a modified multivisceral transplant with a concomitant vascularised sentinel forearm flap. At 48 months after transplantation, our patient remained at full physical activity with no evidence of disease recurrence on either tumour biochemistry or radiological imaging.

Peptide receptor radionuclide therapy: focus on bronchial neuroendocrine tumors

Well-differentiated bronchial neuroendocrine tumors (B-NETs) are rare. They represent 1-5 % of all lung cancers. The incidence of these neoplasms has risen over the past 30 years and, especially for advanced or metastatic disease, management is complex and requires a multidisciplinary approach. Treatment with somatostatin analogs (SSAs) is the most important first-line therapy, in particular in well-differentiated NETs with high somatostatin type receptor (SSTR) expression. In these tumors, the role of mammalian target of rapamycin (m-TOR) inhibitors and the potential utility of other target therapies remain unclear while chemotherapy represents the gold standard treatment only for aggressive forms with low SSTR expression. Peptide receptor radionuclide therapy (PRRT) is an emerging treatment modality for advanced NETs. There are many cumulative evidences about the effectiveness and tolerability of this therapeutic approach, especially in gastro-entero-pancreatic (GEP)-NETs. For B-NETs, scientific research is moving more slowly. Here, we performed a review in order to evaluate the efficacy and toxicity of PRRT with a focus on patients with inoperable or metastatic well-differentiated B-NETs.

Pancreatic neuroendocrine tumors: Challenges in an underestimated disease

Pancreatic neuroendocrine tumours (PanNETs) are considered a relatively unusual oncologic entity. Due to its relative good prognosis, surgery remains the goal standard therapy not only in localized disease but also in the setting of locally or metastatic disease. Most of the patients are diagnosed in metastatic scenario, where multidisciplinary approach based on surgery, chemotherapies, liver-directed and/or molecular targeted therapies are commonly used. Owing to a deeper molecular knowledge of this disease, these targeted therapies are nowadays widely implemented, being the likely discovery of predictive biomarkers that would allow its use in other settings. This review is focused on describing the different classifications, etiology, prognostic biomarkers and multidisciplinary approaches that are typically used in PanNET.