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Transarterial radioembolization (TARE) using β-emitting yttrium-90 microspheres has been used for decades in patients with liver-dominant unresectable metastatic neuroendocrine tumors (mNETs). TARE is one of the embolotherapies supported by the National Comprehensive Cancer Network, among other guidelines, for progressive or symptomatic liver-dominant mNETs. Initial studies with relatively short-term follow-up have indicated that TARE is likely to be at least as effective in controlling symptoms and/or disease progression in the liver as bland or chemoembolization. However, more recent data have shed new light on the risk of long-term hepatotoxicity in patients with mNETs treated with TARE. In this article, we will discuss rationale for TARE, clinical indications, outcomes, and toxicity, as well as new strategies to enhance efficacy of TARE while reducing its toxicity in the treatment of liver-dominant mNETs.

BACKGROUND: MMR proficient (pMMR) colorectal cancer (CRC) is usually unresponsive to immunotherapy. Recent data suggest that ibrutinib may enhance the anti-tumour activity of anti-PD-1 immunotherapy. In this study, we evaluated the safety and efficacy of ibrutinib plus pembrolizumab in refractory metastatic CRC. METHODS: This was a phase 1/2 study in patients with refractory metastatic pMMR CRC. The primary endpoints for phases 1 and 2 were maximum tolerated dose (MTD) and disease control rate, respectively. The secondary endpoints were safety, progression-free survival (PFS) and overall survival (OS). RESULTS: A total of 40 patients were enrolled. No dose-limiting toxicity was observed, and MTD was not identified. The highest tested dose of ibrutinib, 560 mg once daily, was combined with a fixed dose of pembrolizumab 200 mg every 3 weeks for the phase 2 portion. The most common grade 3/4 treatment-related adverse events were anaemia (21%), fatigue (8%) and elevated alkaline phosphatase (8%). Among 31 evaluable patients, 8 (26%) achieved stable disease, and no objective response was observed. The median PFS and OS were 1.4 and 6.6 months, respectively. CONCLUSION: Ibrutinib 560 mg daily plus pembrolizumab 200 mg every 3 weeks appears to be well tolerated with limited anti-cancer activity in metastatic CRC. CLINICALTRIALS.GOV IDENTIFIER: NCT03332498.

Objective Current National Comprehensive Cancer Network guidelines for gastroenteropancreatic neuroendocrine tumors (GEPNETs) recommend complete (R0) surgical resection of the primary tumor and metastases, if feasible. However, large multicenter studies of recurrence patterns of GEPNETs after resection have not been performed. Methods Patients 18 years or older who presented to 7 participating National Comprehensive Cancer Network institutions between 2004 and 2008 with a new diagnosis of a small bowel, pancreas, or colon/rectum neuroendocrine tumor (NET) and underwent R0 resection of the primary tumor, and synchronous metastases, if present, were included in this analysis. Descriptive statistics and Kaplan-Meier estimates were used to calculate recurrence rates and time-associated end points, respectively. Results Of 294 patients with GEPNETs, 50% were male, 88% were White, and 99% had Eastern Cooperative Oncology Group performance status 0 to 1. The median age was 55 years (range, 20-90). The median follow-up time from R0 resection was 62.1 months. Recurrence rates were 18% in small bowel NETs (n = 110), 26% in pancreatic NETs (n = 141), and 10% in colon/rectum NETs (n = 50). The frequency of surveillance imaging was highly variable. Conclusions R0 resection was associated with variable risk of recurrence across subtypes. Further research to inform refinement of guidelines for the appropriate duration of surveillance after R0 resection is needed.

We report the impact of 177Lu-DOTATATE treatment on abdominal pain, diarrhea, and flushing, symptoms that patients with advanced midgut neuroendocrine tumors often find burdensome. Methods: All patients enrolled in the international randomized phase 3 Neuroendocrine Tumors Therapy (NETTER-1) trial (177Lu-DOTATATE plus standard-dose octreotide long-acting repeatable [LAR], n = 117; high-dose octreotide LAR, n = 114) were asked to record the occurrence of predefined symptoms in a daily diary. Change from baseline in symptom scores (mean number of days with a symptom) was analyzed using a mixed model for repeated measures. Results: Patients (intent-to-treat) who received 177Lu-DOTATATE experienced a significantly greater decline from baseline in symptom scores than patients who received high-dose octreotide LAR. For 177Lu-DOTATATE, the mean decline in days with abdominal pain, diarrhea, and flushing was 4.10, 4.55, and 4.52 d per 4 wk, respectively, compared with 0.99, 1.44, and 2.54 d for high-dose octreotide LAR. The mean differences were 3.11 d (95% CI, 1.35–4.88; P = 0.0007) for abdominal pain, 3.11 d (1.18–5.04; P = 0.0017) for diarrhea, and 1.98 d (0.08–3.88; P = 0.0413) for flushing, favoring 177Lu-DOTATATE. A positive repeated-measures correlation was found between diary-recorded symptom scores and questionnaire-recorded pain, diarrhea, and flushing. Conclusion: In addition to efficacy and quality-of-life benefits, symptom diaries from NETTER-1 demonstrated that treatment with 177Lu-DOTATATE was associated with statistically significant reductions in abdominal pain, diarrhea, and flushing, constituting the core symptoms of patients with progressive midgut neuroendocrine tumors, compared with high-dose octreotide LAR, supporting a beneficial effect of 177Lu-DOTATATE on health-related quality of life. Title in Web of Science: Symptom Diaries of Patients with Midgut Neuroendocrine Tumors Treated with Lu-177-DOTATATE

Peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE has been approved for the treatment of gastroenteropancreatic NETs. An understanding of benefits and risks is important for the appropriate implementation of this therapy. This review summarizes study data supporting the use of radiolabeled somatostatin analogs for the treatment of advanced NETs and highlights risks, including potential toxicities in specific populations. Key ongoing clinical trials, including randomized studies, are designed to better define the position of PRRT within the broader therapeutic landscape. Preclinical and early-phase human studies are focused on the development of novel somatostatin-receptor agonists and antagonists, new radionuclides, and radiosensitizing combination therapies.

Background Long-acting somatostatin analogs (SSAs) are the primary first-line treatment of well-differentiated advanced gastroenteropancreatic neuroendocrine tumors (NETs), but data about their efficacy in pancreatic NETs (panNETs) with Ki-67 ≥10% are still limited. Materials and Methods To assess the clinical outcomes of advanced, nonfunctioning, well-differentiated panNETs with Ki-67 ≥10% receiving first-line long-acting SSAs in a real-world setting, we carried out a retrospective, multicenter study including patients treated between 2014–2018 across 10 centers of the NET CONNECT Network. The primary endpoints were time to next treatment (TNT) and progression-free survival (PFS), whereas overall survival (OS) and treatment safety were secondary endpoints. Results A total of 73 patients were included (68 grade [G]2, 5 G3), with liver metastases in 61 cases (84%). After a median follow-up of 36.4 months (range, 6–173), the median TNT and PFS were 14.2 months (95% confidence interval [CI], 11.6–16.2) and 11.9 months (95% CI, 8.6–14.1) respectively. No statistically significant difference was observed according to the somatostatin analog used (octreotide vs. lanreotide), whereas increased tumor grade (hazard ratio [HR], 4.4; 95% CI, 1.2–16.6; p = .04) and hepatic tumor load (HR, 2; 95% CI, 1–4; p = .03) were independently associated with shortened PFS. The median OS recorded was 86 months (95% CI, 56.8–86 months), with poor outcomes observed when the hepatic tumor burden was >25% (HR, 3.4; 95% CI, 1.2–10; p = .01). Treatment-related adverse events were reported in 14 patients, most frequently diarrhea. Conclusion SSAs exert antiproliferative activity in panNETs with Ki-67 ≥10%, particularly in G2 tumors, as well as when hepatic tumor load is ≤25%. Implications for Practice The results of the study call into question the antiproliferative activity of somatostatin analogs (SSAs) in pancreatic neuroendocrine tumors with Ki-67 ≥10%. Patients with grade 2 tumors and with hepatic tumor load ≤25% appear to derive higher benefit from SSAs. Prospective studies are needed to validate these results to optimize tailored therapeutic strategies for this specific patient population.

Background 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) has activity in pancreatic neuroendocrine tumors (pNETs), but its use is limited, partly because of toxicities. pNETs can often become aggressive over time. We evaluated the efficacy of FOLFOX in patients with aggressive pNETs who had progressed after capecitabine plus temozolomide (cap/tem) among other treatments. Materials and Methods This was a retrospective study of all patients with well-differentiated metastatic pNETs, treated at an academic cancer center between January 2008 and June 2019, who received FOLFOX and had received cap/tem in the past. The primary endpoint was objective response rate. Results Thirty-one patients met eligibility criteria. Twenty-five received FOLFOX, and six received FOLFOX with bevacizumab. Patients were heavily pretreated, having received a median of three prior lines of systemic therapy prior to FOLFOX (range, 1–8). Three (9.7%) patients had grade [G]1 tumors, 16 (51.6%) had G2, and 6 (19.4%) had G3, and grade was unspecified in 6 (19.4%) patients. Fourteen (45.2%) exhibited a best response of partial radiographic response per RECIST 1.1 criteria, 15 (48.4%) stable disease, and 2 (6.4%) progressive disease; overall response rate was 45.2% and disease control rate was 93.5%. Median progression-free survival was 6 months (95% confidence interval [CI], 5.0–7.0), and median overall survival was 16 months from onset of study treatment (95% CI, 11.3–20.7) and 67 months from date of diagnosis (95% CI, 49.8–84.2). Median duration of treatment was 3 months, and median duration of response was 2 months. Toxicity profile was consistent with known adverse events associated with this regimen. Conclusion FOLFOX is active in aggressive, heavily pretreated pNETs that have progressed on prior cap/tem chemotherapy; response durations are relatively short. Implications for Practice FOLFOX chemotherapy has robust activity in patients with rapidly progressive, heavily pretreated pancreatic neuroendocrine tumors (NETs), a setting in which few, if any, other options are likely to be effective. Durations of response, however, are relatively short, and new treatments are urgently needed for patients with aggressive transformation of pancreatic NETs.

Although radiation-induced mesenteritis or peritonitis can potentially exacerbate the risk of bowel obstruction, there are no data in the literature on the incidence of intestinal obstruction related to peptide receptor radionuclide therapy. Methods: The records of all patients treated with 177Lu-DOTATATE at Moffitt Cancer Center between April 2018 and October 2019 were evaluated. The number of patients who developed bowel obstruction within 3 mo of a 177Lu-DOTATATE treatment was divided by the total number of patients with preexisting peritoneal or mesenteric disease. Management strategies and outcomes were evaluated. Results: Of a total of 159 patients treated, 81 had baseline mesenteric or peritoneal disease, among whom 5 (6%) experienced at least 1 episode of bowel obstruction within 3 mo of treatment. Two of the patients underwent surgical exploration during obstruction describing a “frozen abdomen.” All 5 responded at least temporarily to high-dose corticosteroid treatment and regained bowel function, but 2 patients eventually succumbed to progressive peritoneal disease. Conclusion: Peptide receptor radionuclide therapy can lead to bowel obstruction in patients with mesenteric or peritoneal disease, likely by inducing inflammation. Corticosteroids can potentially play a role in treatment and prophylaxis.

Background Metastatic high-grade neuroendocrine neoplasms (G3NENs) have limited treatment options after progression on platinum-based therapy. We addressed the role of Pembrolizumab in patients with previously treated metastatic G3NENs. Methods Two open-label, phase 2 studies enrolled patients with G3NEN (Ki-67 > 20%) to receive Pembrolizumab at 200 mg I.V. every 3 weeks. Radiographic evaluation was conducted every 9 weeks with overall response rate as the primary endpoint. Results Between November 2016 and May 2018, 29 patients (13 males/16 females) with G3NENs were enrolled. One patient (3.4%) had an objective response and an additional six patients (20.7%) had stable disease, resulting in a disease control rate of 24.1%. Disease control rate (DCR) at 18 weeks was 10.3% (3/29). There was no difference in the DCR, PFS or OS between the PD-L1-negative and -positive groups (p 0.56, 0.88 and 0.55, respectively). Pembrolizumab was well tolerated with only 9 grade 3, and no grade 4 events considered drug-related. Conclusions Pembrolizumab can be safely administered to patients with G3NENs but has limited activity as a single agent. Successful completion of our trials suggest studies in G3NENs are feasible and present an unmet need. Further research to identify active combination therapies should be considered. Clinical trial registration number NCT02939651 (10/20/2016).

Background: Carcinoid heart disease (CaHD) is a rare condition that has a high impact on the morbidity and mortality of its patients. Once heart failure symptoms develop in the patient with CaHD, cardiac valve surgery is often the only effective treatment. Although atrioventricular block (AVB) is a known postoperative complication of the valve surgery, the incidence of AVB in this population has not been well described. Methods: Comprehensive records were collected retrospectively on consecutive patients with CaHD who underwent a valve surgery at a tertiary medical center from January 2001 to December 2015. We excluded patients with pre-existing permanent pacemaker (PPM). Results: Nineteen consecutive patients were included in this study and 18 of them underwent at least dual valve (tricuspid and pulmonary valve) replacement surgery. Our 30-day post-surgical mortality was 0%. During the 6-month observation period following the surgery, 31.5% (n = 6) required PPM implantation due to complete AVB. There was no statistical difference in baseline characteristics and electrocardiographic and echocardiographic parameters between the patients who did or did not require PPM placement. Conclusions: Our study revealed that almost one-third of CaHD patients who underwent a valve replacement surgery developed AVB requiring PPM implantation. Due to high incidence of PPM requirement, we believe that prophylactic placement of an epicardial lead during the valve surgery can be helpful in these patients to reduce serious complication from placement of pacemaker lead on a later date through a prosthetic valve. Cardiol Res. 2020;11(1):56-60 doi: https://doi.org/10.14740/cr986

Objective The pathogenesis of pancreatic neuroendocrine tumors (PNETs) is still unclear. We propose Frabin as a new molecular alteration in PNETs. Frabin is a guanine nucleotide exchange factor playing a role in mediating actin cytoskeleton changes during cell migration, morphogenesis, polarization, and division. Methods Patients with PNETs of different grades were assessed for Frabin expression using immunohistochemistry and tissue microarray. The tissue microarray included 12 grade 1 and 3 grade 2 PNETs and 14 grade 3 pancreatic neuroendocrine carcinomas (PECAs). Frabin immunostain was scored with Allred system. Statistical analysis used SAS and R software. Immunohistochemistry scores were correlated with tumor grade and stage. The Spearman correlation coefficient was calculated with P values. Results Pancreatic neuroendocrine tumors were graded according to the World Health Organization 2017 guidelines. Frabin was expressed by 24 (82.7%) of the PNET/PECA studied. Only 5 (17.2%) of the 29 PNETs/PECA evaluated were Frabin negative. Frabin expression was cytoplasmic in all cases. We found a significant positive correlation (ρ = 0.47) between Frabin immunohistochemistry score and tumor grade (P = 0.01). No correlation was found between Frabin expression and tumor stage (P = 0.91). Conclusions We report Frabin overexpression as a novel molecular alteration occurring in PNETs/PECAs.

INTRODUCTION: (177)Lutetium-[DOTA°,Tyr(3)]octreotate ((177)Lu-DOTATATE) is a type of peptide receptor radionuclide therapy that garnered FDA approval in January 2018 for the treatment of somatostatin receptor-positive gastroenteropancreatic (GEP) neuroendocrine tumor (NET) patients. The therapy approval was based on findings from the randomized international phase III NETTER-1 trial as well as outcome data from a large European registry. The mechanism of the drug stems directly from its structure: a somatostatin analog (octreotate) selectively binding to somatostatin receptor expressing cells and being internalized, along with a chelated beta-emitting isotope (177)Lu. AREAS COVERED: Herein we describe the pharmacology, clinical efficacy and adverse event data from prospective and retrospective studies with (177)Lu-DOTATATE. We discuss the role of (177)Lu-DOTATATE within the current treatment landscape for GEP NET patients. EXPERT OPINION: (177)Lu-DOTATATE represents a unique addition to the treatment armamentarium for GEP NETs because of its potential to elicit tumor cytoreduction, which is rare among other existing treatment options, and prolonged disease control. Where (177)Lu-DOTATATE fits into the treatment sequence for GEP NET patients remains an area of active investigation.

Background: Ibrutinib is an orally administered inhibitor of Bruton’s tyrosine kinase (Btk). Preclinical data suggest that mast cells are recruited within neuroendocrine neoplasms (NENs) where they stimulate angiogenesis and tumor growth. Ibrutinib inhibits mast cell degranulation and has been associated with regression of tumors in a mouse insulinoma model. Methods: A prospective, phase II trial evaluated patients with advanced gastrointestinal (GI)/lung NENs and pancreatic NENs (pNENs) who had evidence of progression within 12 months of study entry on at least one prior therapy. Patients received ibrutinib 560 mg daily until unacceptable toxicity, progression of disease, or withdrawal of consent. The primary endpoint was objective response rate. Results: Twenty patients were enrolled on protocol from November 2015 to December 2017 (15 advanced GI/lung NENs and 5 pNENs). No patient reached an objective response. Median PFS was 3.0 months. A total of 44 drug-related adverse events (AEs) were captured as probably or definitely associated with ibrutinib. Five patients experienced probably or definitely related grade 3 AEs, and 1 patient experienced a probably related grade 4 AE. Five patients discontinued treatment prior to radiographic assessment. Conclusions: Ibrutinib does not show significant evidence of activity in well-differentiated gastroenteropancreatic and lung NENs.

With the recent approval of 177Lu-DOTATATE for use in gastroenteropancreatic neuroendocrine tumors, access to peptide receptor radionuclide therapy is increasing. Representatives from the North American Neuroendocrine Tumor Society and the Society of Nuclear Medicine and Molecular Imaging collaborated to develop a practical consensus guideline for the administration of 177Lu-DOTATATE. In this paper, we discuss patient screening, maintenance somatostatin analog therapy requirements, treatment location and room preparation, drug administration, and patient release as well as strategies for radiation safety, toxicity monitoring, management of potential complications, and follow-up. Controversies regarding the role of radiation dosimetry are discussed as well. This document is designed to provide practical guidance on how to safely treat patients with this therapy.

Background and study aims Pancreatic neuroendocrine tumors (P-NENs) are rare tumors with malignant potential. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been shown to be superior to other imaging methods in preoperative localization and diagnosis of P-NENs. The objective of this study was to describe the EUS features of non-metastatic cystic and non-cystic P-NENs seen at a referral center and to evaluate the performance of EUS-FNA in diagnosis of P-NENs. Patients and methods All patients with histologically confirmed, non-metastatic P-NENs, which underwent EUS-FNA prior to surgical resection at the Moffitt Cancer Center between Jan 2005 and Dec 2012 were included. Clinical, endoscopic and pathologic information was abstracted from electronic medical records. Results Thirty-nine patients, all with non-functional P-NENs, were included in this study. Thirteen tumors were cystic and 26 were solid. Among the cystic tumors, 50 % were partly cystic and partly solid, and 50 % were fully cystic. The cystic tumors were more commonly seen at the body/tail, and the solid tumors were more uniformly distributed. Fluid could be aspirated from 50 % of the cystic tumors, all with a carcinoembryonic antigen level Conclusions EUS-FNA is much more sensitive in diagnosing solid P-NENs than cystic PNETs. Our results indicate that EUS-FNA may have higher sensitivity for diagnosis of cystic P-NENs than the reported sensitivity of EUS-FNA for all pancreatic cystic tumors.

Patients with carcinoid syndrome diarrhea that is not controlled with long‐acting somatostatin analogs can benefit from the addition of the tryptophan hydroxylase inhibitor, telotristat ethyl. This article evaluates the real‐world effectiveness of telotristat ethyl using patient‐reported data., Background. When carcinoid syndrome (CS) diarrhea (CSD) is inadequately controlled with long‐acting somatostatin analogs (SSAs), clinical practice guidelines recommend addition of the tryptophan hydroxylase inhibitor telotristat ethyl (TE). In a 12‐week multinational, randomized controlled trial, TE added to SSA reduced peripheral serotonin and the frequency of CSD. We evaluated real‐world effectiveness of TE using patient‐reported data from a nurse support program over 3 months. Materials and Methods. This study used a deidentified data set of patients initiating TE who opted into a nurse support program between March and November 2017 and reported CS symptom burden at baseline and at least one follow‐up time point at months 1, 2, and 3. Patients reported demographic and medical history information as well as frequency of bowel movements (BMs) and flushing episodes, severity of nausea, urgency and abdominal pain (0 “no/not at all” to 100 “worst imaginable/very urgent”), and stool form (1 “very hard” to 10 “watery”). Mean changes from baseline in CS symptom burden were reported using paired‐sample t tests and Wilcoxon signed‐rank tests. Results. Most patients initiating TE enrolled in the nurse program (791/898, 88%), of whom 369 (47%) were included in the analysis. Patients treated with TE reported significant reductions in CSD and other CS symptoms (all p < .001). At least half of patients treated with TE experienced ≥30% improvement from baseline in BM frequency and an average reduction of at least two BMs per day within 3 months. Conclusion. Patients taking SSA therapy showed substantial burden of disease before initiating TE and significant improvements with the addition of TE treatment in this real‐world effectiveness study. Implications for Practice. Patients with carcinoid syndrome diarrhea uncontrolled by high doses of long‐acting somatostatin analogs may be candidates for additional therapy with the tryptophan hydroxylase inhibitor telotristat ethyl. Understanding the real‐world prevalence of uncontrolled symptoms and the effectiveness of telotristat ethyl in clinical practice may further support clinical and policy decisions for these patients. This study investigated self‐reported carcinoid syndrome symptom burden and improvements among patients initiating telotristat ethyl and participating in a voluntary nurse support program. Disease burden and off‐label somatostatin analog treatment before initiating telotristat ethyl were high, and symptoms improved markedly over 1, 2, and 3 months of treatment.

Simple Summary Cytotoxic chemotherapy is a standard therapy for patients with poorly differentiated neuroendocrine carcinomas, however, its role in patients with well differentiated neuroendocrine tumors is less defined. In this review, we describe the data supporting many of the chemotherapy regimens which have been tested in patients with well differentiated neuroendocrine tumors, specifically focusing on the impact of tumor features (e.g., primary tumor origin, grade and DNA damage repair defects) on chemosensitivity, and discuss future directions for chemotherapy as a combinatorial treatment modality for patients with this disease. Abstract The role for cytotoxic chemotherapy in patients with well-differentiated neuroendocrine tumors (NETs) remains debated. Compared to patients with poorly differentiated neuroendocrine carcinomas (NECs) where chemotherapy is utilized ubiquitously, chemotherapy may play a more select role in patients with certain types of NETs (e.g., pancreatic tumors, higher grade tumors, and tumors possessing DNA damage repair defects). The primary types of chemotherapy that have been tested in patients with NETs include alkylating agent- and platinum agent-based combinations. Across regimens, chemotherapy appears to elicit greater antitumor activity in patients with pancreatic or grade 3 NETs. The role for chemotherapy in lower grade extra-pancreatic NETs remains undefined. Furthermore, while chemotherapy has demonstrated clinically meaningful benefit for patients in the systemic setting, its role in the adjuvant or neoadjuvant setting is as-of-yet undetermined. Finally, efforts to combine chemotherapy with targeted therapy and peptide receptor radionuclide therapy are ongoing, in hopes of improving the cytoreductive treatment options for patients with NETs.

1669 Introduction: Microcalcification in the arterial wall traced by 18F-sodium fluoride (NaF) positron emission tomography (PET) is considered an indicator of early phase atherosclerosis and a potential precursor of macrocalcification detectable by computed tomography (CT). Ongoing carotid artery disease is a major cause of stroke that typically occurs without preceding symptoms. Thus, methods that can detect and monitor early phase carotid atherosclerosis may be of clinical interest. We aimed to examine 2-year changes in carotid NaF uptake by means of repeat NaF-PET/CT. Methods: Twenty-nine healthy subjects and 20 angina pectoris patients underwent 90-min NaF-PET/CT twice two years apart using the same scanner in each patient on both occasions. The right and left main carotid arteries were manually segmented. NaF uptake was expressed as the mean and total standardized uptake values without and with partial volume correction (SUVmean, SUVtotal and cSUVmean, cSUVtotal). Results: Recorded NaF uptake values are shown in Table 1. Insignificant tendencies were similar or higher NaF uptake in angina patients at both time points with less uptake in healthy subjects and generally higher uptake in angina patients after 2 years. Thus, mean (± standard deviation) right carotid cSUVmean of angina patients was 1.84±0.56 and 1.88±0.97 at baseline and after 2 years (p=0.15) vs. 1.62±0.35 and 1.44±0.36 in healthy subjects (p=0.001). Similarly, left carotid cSUVmean of angina patients was 1.5±0.44 and 1.53±0.51 at baseline and after 2 years (p=0.87) vs. 1.43±0.23 and 1.34±0.27 in healthy subjects (p=0.08). NaF uptake at baseline could not predict a change in CT-calcification after 2 years. Conclusions: Slightly higher NaF uptake in the angina group indicated more ongoing carotid microcalcification at both time points in patients than in healthy subjects. The 2-year changes were very small in both groups, albeit with a tendency of slight decreases among healthy controls, suggesting a more dynamic, waxing and waning, process in these compared to a slow, but more consistent, progression in angina patients despite statin therapy in half of these.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Neuroendocrine and Adrenal Gland Tumors focus on the diagnosis, treatment, and management of patients with neuroendocrine tumors (NETs), adrenal tumors, pheochromocytomas, paragangliomas, and multiple endocrine neoplasia. NETs are generally subclassified by site of origin, stage, and histologic characteristics. Appropriate diagnosis and treatment of NETs often involves collaboration between specialists in multiple disciplines, using specific biochemical, radiologic, and surgical methods. Specialists include pathologists, endocrinologists, radiologists (including nuclear medicine specialists), and medical, radiation, and surgical oncologists. These guidelines discuss the diagnosis and management of both sporadic and hereditary neuroendocrine and adrenal tumors and are intended to assist with clinical decision-making. This article is focused on the 2021 NCCN Guidelines principles of genetic risk assessment and counseling and recommendations for well-differentiated grade 3 NETs, poorly differentiated neuroendocrine carcinomas, adrenal tumors, pheochromocytomas, and paragangliomas.

Targeted radionuclide therapies (TRT) using 131I-metaiodobenzylguanidine (131I-MIBG) and peptide receptor radionuclide therapy (177Lu or 90Y) represent several of the therapeutic options in the management of metastatic/inoperable pheochromocytoma/paraganglioma. Recently, high-specific-activity-131I-MIBG therapy was approved by the FDA and both 177Lu-DOTATATE and 131I-MIBG therapy were recommended by the National Comprehensive Cancer Network guidelines for the treatment of metastatic pheochromocytoma/paraganglioma. However, a clinical dilemma often arises in the selection of TRT, especially when a patient can be treated with either type of therapy based on eligibility by MIBG and somatostatin receptor imaging. To address this problem, we assembled a group of international experts, including oncologists, endocrinologists, and nuclear medicine physicians, with substantial experience in treating neuroendocrine tumors with TRTs to develop consensus and provide expert recommendations and perspectives on how to select between these two therapeutic options for metastatic/inoperable pheochromocytoma/paraganglioma. This article aims to summarize the survival outcomes of the available TRTs; discuss personalized treatment strategies based on functional imaging scans; address practical issues, including regulatory approvals; and compare toxicities and risk factors across treatments. Furthermore, it discusses the emerging TRTs.

Background The authors previously reported the results of the nonpancreatic neuroendocrine neoplasm cohort of the SWOG S1609 DART (Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors) trial, which permitted all histologic grades and had a 44% overall response rate (ORR) among patients with high-grade disease. Here they sought to validate their findings in a dedicated prospective cohort of high-grade neuroendocrine neoplasms within S1609. Methods A prospective, open-label, multicenter, phase 2 clinical trial of ipilimumab plus nivolumab was conducted across multiple rare tumor cohorts. The dedicated, high-grade neuroendocrine neoplasm cohort was examined here. The primary end point was the ORR according to version 1.1 of the Response Evaluation Criteria in Solid Tumors. Secondary end points included progression-free survival (PFS), overall survival (OS), and toxicity. Results Nineteen patients with high-grade neuroendocrine neoplasms (defined by local pathology review) were enrolled in this cohort of S1609. The most common primary sites were unknown primaries (21%), which were followed by the rectum, gastroesophageal junction, cervix, and pancreas (11%). The median number of lines of prior therapy was 1 (range, 0-3). All patients were microsatellite-stable. The median Ki-67 value was 80%. The ORR was 26% (95% confidence interval [CI], 11%-45%), and the clinical benefit rate (stable disease for ≥6 months plus partial responses plus complete responses) was 32% (95% CI, 13%-57%). The 6-month PFS rate was 32% (95% CI, 16%-61%) with a median PFS of 2.0 months (95% CI, 1.8 months to ∞) and a median OS of 8.7 months (95% CI, 6.1 months to ∞). The most common toxicities were fatigue (32%) and rash (26%), and the most common grade 3/4 immune-related adverse event was rash (15%); there were no events that required treatment discontinuation and no grade 5 events. Conclusions Ipilimumab plus nivolumab demonstrated a 26% ORR in patients with high-grade neuroendocrine neoplasms, with durable responses seen in patients with refractory disease.

OBJECTIVE The aim of the study was to assess the impact of systemic markers of inflammation on the outcomes in patients with neuroendocrine tumors (NETs) treated with everolimus or placebo (as measured by baseline neutrophil-to-lymphocyte ratio [NLR] and lymphocyte-to-monocyte ratio [LMR]). METHODS Patient data (gastrointestinal, pancreatic, and lung NETs) from 2 large phase 3 studies, RADIANT-3 (n = 410) and RADIANT-4 (n = 302), were pooled and analyzed. The primary end point was centrally assessed progression-free survival (PFS) as estimated by the Kaplan-Meier method. RESULTS In the pooled population, elevated LMR (median PFS, 11.1 months; 95% confidence interval, 9.3-13.7; hazard ratio, 0.69; P < 0.001) and reduced NLR (median PFS, 10.8 months; 95% confidence interval, 9.2-11.7; hazard ratio, 0.75; P = 0.0060) correlated with longer PFS among all patients. These markers were also found to be prognostic in the everolimus- and placebo-treated subgroups. CONCLUSIONS Data from this study suggest that LMR and NLR are robust prognostic markers for NETs and could potentially be used to identify patients who may receive or are receiving the most benefit from targeted therapies. As both are derived from a complete blood count, they can be routinely used in clinical practice, providing valuable information to clinicians and patients alike.

Despite efforts to enhance enrollment and the merger of national cooperative groups, < 5% of patients with cancer will enroll into a clinical trial. Additionally, clinical trials are affected by a lack of diversity inclusive of minority patients, rural residents, or low-income individuals. COVID-19 further exacerbated known barriers of reduced physician-patient interaction, physician availability, trial activation and enrollment, financial resources, and capacity for conducting research. Based on the cumulative insight of academic and community clinical researchers, we have created a white paper identifying existing challenges in clinical trial conduct and have provided specific recommendations of sustainable modifications to improve efficiency in the activation and conduct of clinical trials with an overarching goal of providing improved access and care to our patients with cancer.

We report the impact of

Gastroenteropancreatic neuroendocrine tumors are relatively rare neoplasms, characterized by a propensity to secrete hormones that cause distinct clinical syndromes. During the past decade, the systemic treatment landscape has improved significantly: new options include everolimus, an inhibitor of the mammalian target of rapamycin; sunitinib, an angiogenesis inhibitor; and cytotoxic regimens such as capecitabine and temozolomide. Moreover, the recent approval of the radiolabeled somatostatin analog 177Lu-DOTATATE has had a significant impact on management of neuroendocrine malignancies. In this review, we discuss advances in the medical management of gastroenteropancreatic neuroendocrine tumors within the context of the larger multidisciplinary approach to these diseases.

Purpose: KEYNOTE-158 (ClinicalTrials.gov identifier: NCT02628067) investigated the efficacy and safety of pembrolizumab across multiple cancers. We present results from patients with previously treated advanced well-differentiated neuroendocrine tumors (NET). Patients and Methods: Pembrolizumab 200 mg was administered every 3 weeks for 2 years or until progression, intolerable toxicity, or physician/patient decision. Tumor imaging was performed every 9 weeks for the first year and then every 12 weeks. Endpoints included objective response rate (ORR) per RECIST v1.1 by independent central radiologic review (primary) and duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety (secondary). Results: A total of 107 patients with NETs of the lung, appendix, small intestine, colon, rectum, or pancreas were treated. Median age was 59.0 years (range, 29–80), 44.9% had ECOG performance status 1, 40.2% had received ≥3 prior therapies for advanced disease, and 15.9% had PD-L1–positive tumors (combined positive score ≥1). Median follow-up was 24.2 months (range, 0.6–33.4). ORR was 3.7% (95% CI, 1.0–9.3), with zero complete responses and four partial responses (three pancreatic and one rectal) all in patients with PD-L1–negative tumors. Median DOR was not reached, with one of four responses ongoing after ≥21 months follow-up. Median PFS was 4.1 months (95% CI, 3.5–5.4); the 6-month PFS rate was 39.3%. Median OS was 24.2 months (95% CI, 15.8–32.5). Treatment-related adverse events (AE) occurred in 75.7% of patients, 21.5% of whom had grade 3–5 AEs. Conclusions: Pembrolizumab monotherapy showed limited antitumor activity and manageable safety in patients with previously treated advanced well-differentiated NETs.

Neuroendocrine tumors (NETs) are heterogeneous malignancies arising from the diffuse neuroendocrine system. They frequently originate in the gastroenteropancreatic (GEP) tract and the bronchopulmonary tree, and their incidence has steadily increased in the last 3 decades. Fundamental biologic and genomic differences underlie the clinical heterogeneity of NETs, and distinct molecular features characterize NETs of different grades and different primary sites. Although surgery remains the cornerstone of treatment for localized tumors, systemic treatment options for patients with metastatic NETs have expanded considerably. Somatostatin analogs have demonstrated both antisecretory and antitumor efficacy. Peptide receptor radionuclide therapy with lutetium-177 dotatate (177 Lu-DOTATATE) has been approved for advanced GEP-NETs. The antitumor activity of everolimus has been demonstrated across a wide spectrum of NETs, and the antiangiogenic agent sunitinib has been approved for pancreatic NETs (pNETs). Chemotherapy with temozolomide and capecitabine has recently demonstrated an unprecedented prolongation of progression-free survival in a randomized trial of pNETs. Multiple retrospective series have reported the efficacy of liver-directed therapies both for palliating symptoms of hormone excess and for controlling tumor growth. Telotristat, an oral inhibitor of tryptophan hydroxylase, has been shown to reduce diarrhea in patients with carcinoid syndrome. Defining the therapeutic algorithm and identifying biomarkers predictive of response to treatments are among the main priorities for the next decade of research in the NET field.

Neuroendocrine neoplasms (NEN) most commonly arise in the gastroenteropancreatic system and lungs. The incidence of NEN is increasing globally, with improved diagnostic techniques identifying patients with early-stage disease. The number of approved therapies for the treatment of advanced disease has grown substantially in the past decade. The treatment algorithm for advanced NEN is evolving from one that is directed by primary site–specific classification to one that is directed by biologic classification, as evidenced by overlapping systemic treatments across the primary tumor sites. Commonalities in biologic characteristics across primary sites include functional status, differentiation status, grade, level of somatostatin receptor expression, and genetic alterations. In this review, we discuss current clinical evidence and available therapies for the treatment of advanced NEN and highlight the need for prospective trials in patients with well-differentiated, high-grade NEN. Implications for Practice This review raises awareness of the evolution of the treatment algorithm for advanced neuroendocrine neoplasms (NEN) from one that is directed by primary tumor site–specific classification to one that is directed by biologic classification. In addition, this review promotes understanding of the new pathologic category of well-differentiated G3 pancreatic neuroendocrine tumors and highlights the need for prospective trials in this patient population, for whom there is currently no standard of care. This review further provides a conceptual treatment schematic that categorizes the recommendations for systemic treatments for advanced disease by biologic classification, including the new and established categories of NEN.

Objectives Early-phase clinical trials play a pivotal role in drug development. However, limited data are available on outcomes of gastrointestinal (GI) cancer patients enrolled in phase I clinical trials. Here, we evaluated the characteristics associated with survival in GI cancer patients participating in phase I clinical trials and attempted to validate previously established prognostic models. Materials and methods All consecutive patients with advanced GI tumors who participated in phase I clinical trials at our institution from January 2007 to December 2013 and received at least 1 dose of the study drug were included. Cox regression models were used to estimate multivariable-adjusted hazard ratio (HR) and 95% confidence interval. Results In 243 study patients (median age, 62 y [range, 26 to 82 y]; 55% male), treatment included chemotherapy only (14%), targeted therapy (41%), chemotherapy+targeted therapy (42%), and others (2%) for the following disease types: pancreatic (42%), colorectal (34%), gastroesophageal (10%), hepatobiliary (13%), and others (2%). Response rate was 4%, with 38% achieving stable disease and 42% having progressive disease. Median survival was 5.8 months (range, 0.2 to 52.4 mo). Our multivariable Cox regression analyses included the following as predictors of survival: Eastern Cooperative Oncology Group performance score ≥1 (HR=1.76), prior systemic therapies ≥2 (HR=1.63), lactate dehydrogenase >618 IU/L (HR=1.85), sodium >135 mmol/L (HR=0.46), and white blood count >6×10/L (HR=1.5). Our data set was consistent with previous prognostic scores. Conclusions This is the largest study to assess clinical outcomes in this patient population. Phase I trials provide clinical benefit to patients with advanced GI malignancies and should be recommended as a treatment option in appropriate patients.

Purpose: The purpose of this study was to evaluate the safety and efficacy of ontuxizumab (MORAb-004), a monoclonal antibody that interferes with endosialin (tumor endothelial marker-1) function, in patients with chemorefractory metastatic colorectal cancer and to identify a responsive patient population based on biomarkers. Experimental Design: This was a randomized, double-blind, placebo-controlled, phase II study. Patients were randomly assigned in a 2:1 ratio to receive weekly intravenous ontuxizumab (8 mg/kg) or placebo plus best supportive care until progression or unacceptable toxicity. Tissue and blood biomarkers were evaluated for their ability to identify a patient population that was responsive to ontuxizumab. Results: A total of 126 patients were enrolled. No significant difference between the ontuxizumab and placebo groups was evident for the primary endpoint of progression-free survival (PFS), with a median PFS of 8.1 weeks in each group (HR, 1.13; 95% confidence interval, 0.76–1.67; P = 0.53). There were no significant differences between groups for overall survival (OS) or overall response rate (ORR). The most common treatment-emergent adverse events (TEAEs) in the ontuxizumab group (vs. the placebo group, respectively) were fatigue (53.7% vs. 47.5%), nausea (39.0% vs. 35.0%), decreased appetite (34.1% vs. 27.5%), and constipation (28.0% vs. 32.5%). The most common grade 3/4 TEAE in the ontuxizumab group versus placebo was back pain (11.0% vs. 0%). No single biomarker clearly identified patients responsive to ontuxizumab. Conclusions: No benefit with ontuxizumab monotherapy compared with placebo for clinical response parameters of PFS, OS, or ORR was demonstrated. Ontuxizumab was well tolerated. Clin Cancer Res; 24(2); 316–25. ©2017 AACR.

Roberto Buzzoni,1 Carlo Carnaghi,2 Jonathan Strosberg,3 Nicola Fazio,4 Simron Singh,5 Fabian Herbst,6 Antonia Ridolfi,7 Marianne E Pavel,8 Edward M Wolin,9 Juan W Valle,10 Do-Youn Oh,11 James C Yao,12 Rodney Pommier13 1IRCCS Foundation, National Institute of Tumors, Milan, Italy; 2Humanitas Clinical and Research Center, Rozzano, Italy; 3Moffitt Cancer Center, Tampa, FL, USA; 4European Institute of Oncology, Milan, Italy; 5Sunnybrook Health Sciences Centre, Toronto, ON, Canada; 6Novartis AG, Basel, Switzerland; 7Novartis Pharma S.A.S., Rueil-Malmaison, France; 8Medizinische Klinik 1, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; 9Montefiore Einstein Center for Cancer Care, Bronx, NY, USA; 10Institute of Cancer Sciences, University of Manchester, The Christie Hospital, Manchester, UK; 11Seoul National University Hospital, Seoul, Republic of Korea; 12University of Texas M.D. Anderson Cancer Center, Houston, TX, USA; 13Oregon Health & Science University, Portland, OR, USA Background: Recently, everolimus was shown to improve median progression-free survival (PFS) by 7.1 months in patients with advanced, progressive, well-differentiated, nonfunctional neuroendocrine tumors (NET) of lung or gastrointestinal (GI) tract compared with placebo (HR, 0.48; 95% CI, 0.35–0.67; P

With the growing use of 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT), there are many unanswered questions regarding patient selection. In this document, we review the literature on the use of 177Lu-DOTATATE in neuroendocrine tumors (NETs) of different primary origin, discuss issues of

The novel coronavirus disease 2019 (COVID-19) is now considered a pandemic imposing a tremendous challenge on many nuclear medicine departments. Whereas preliminary precautions have been addressed regarding the risk of infection ([1][1]), the potential impact of COVID-19 on the risk–benefit ratio

Lung neuroendocrine tumors (LNETs) are uncommon cancers, and there is a paucity of randomized evidence to guide practice. As a result, current guidelines from different neuroendocrine tumor societies vary considerably. There is a need to update and harmonize global consensus guidelines. This article reports the best practice guidelines produced by a collaboration between the Commonwealth Neuroendocrine Tumour Research Collaboration and the North American Neuroendocrine Tumor Society. We performed a formal endorsement and updating process of the 2015 European Neuroendocrine Tumor Society expert consensus article on LNET. A systematic review from January 2013 to October 2017 was conducted to procure the most recent evidence. The stepwise endorsement process involved experts from all major subspecialties, patients, and advocates. Guided by discussion of the most recent evidence, each statement from the European Neuroendocrine Tumor Society was either endorsed, modified, or removed. New consensus statements were added if appropriate. The search yielded 1109 new publications, of which 230 met the inclusion criteria. A total of 12 statements were endorsed, 22 statements were modified or updated, one was removed, and two were added. Critical answered questions for each topic in LNET were identified. Through the consensus process, guidelines for the management of patients with local and metastatic neuroendocrine tumors have been updated to include both recent evidence and practice changes relating to technological and definitional advances. The guidelines provide clear, evidence-based statements aimed at harmonizing the global approach to patients with LNETs, on the basis of the principles of person-centered and LNET-specific care. The importance of LNET-directed research and person-centered care throughout the diagnosis, treatment, and follow-up journey is emphasized along with directions for future collaborative research.

Background Patients with advanced lung neuroendocrine neoplasms (NENs) have few treatment options. Capecitabine and temozolomide have recently showed significant activity in patients with pancreatic neuroendocrine tumors (NETs), but data in lung NETs are limited. Methods We retrospectively reviewed the records of patients treated at a large referral center to identify patients seen between January 2008 and September 2018 with metastatic lung NENs who received treatment with capecitabine and temozolomide (CAPTEM). Patients with small cell lung cancer were excluded. The primary endpoint was overall response rate per RECIST 1.1. Secondary endpoints included progression-free survival, overall survival, and toxicity. Results Twenty patients were identified who received treatment with capecitabine and temozolomide. Fourteen (70%) had typical lung NETs, five had (25%) atypical carcinoids, and one (5%) had disease defined as a large-cell neuroendocrine carcinoma. Nineteen patients were evaluable for response. Six (30%) patients exhibited a best response of partial response per RECIST 1.1 criteria, 11 (55%) stable disease, and 2 (10%) progressive disease; objective response rate was 30%, and disease control rate was 85%. Eleven patients eventually progressed, only six of whom exhibited progression per RECIST 1.1 criteria. Median progression-free survival was 13 months (95% confidence interval [CI], 4.4–21.6 months). Median overall survival was 68 months (95% CI, 35.3–100.7 months). Toxicity profile was mild with mainly grade 1, expected toxicities. Six patients required dose reduction because of toxicity. Conclusion The CAPTEM regimen is associated with a high response rate and a relatively tolerable toxicity profile in lung NENs. This regimen warrants further exploration in a prospective clinical trial.

Background/aim Low-grade pancreatic neuroendocrine tumors (LG-PNETs) behave unpredictably. The aim of the study was to identify biomarkers that predict PNET metastasis to improve treatment selection. Patients and methods Five patients with primary non-metastatic LG-PNETs, six with primary LG-PNETs with synchronous or metachronous metastases (M-PNETs), and six metastatic to liver LG-PNETs (ML-PNETs) from the group of six M-PNET patients were selected. RNA data were normalized using iterative rank-order normalization. Student's t-test identified differentially-expressed genes in LG-PNETs versus M-PNETs. A 2-fold difference in expression was considered to be significant. Results were validated with an independent dataset of LG-PNETs and metastatic LG-PNETs. Results Overall, 195 genes had a >2-fold change (in either direction). A total of 29 genes were differentially overexpressed in M-PNETs. Erythrocyte membrane protein band 4.1-like 5 (EPB41L5) had a 2.07-fold change increase in M-PNETs and the smallest p-value. EPB41L5 was not statistically different between M-PNETs and ML-PNETs. EPB41L5 differential expression between primary and metastatic LG-PNETs was confirmed by immunohistochemistry. Conclusion These results support further investigation into whether EPB41L5 is a biomarker of PNETs with high risk for metastases.

REPLY: Dr. Wee and colleagues reviewed their database of gastroenteropancreatic neuroendocrine tumor patients treated with 177Lu-DOTATATE and observed patterns of bowel obstruction very similar to those described in our study ( [1][1] ). These corroborating data significantly strengthen the evidence

Background Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) make up 75% of all NETs and are often diagnosed at an advanced state with only limited treatment options. Current standard therapies include somatostatin (SST) analogues and targeted drugs such as mTOR inhibitor Everolimus. While these treatments may achieve disease stabilization for a limited time, they rarely induce objective tumor remission. PRRT has recently emerged as a promising option providing more durable responses and potentially higher objective response rates. It uses radiolabeled SST analogues which specifically target and destroy tumor cells, this way significantly sparing benign tissues. PRRT with radiolabeled SST receptor (SSTR)-ligands, such as 177Lu-DOTATATE in NETTER-1, has shown promising results in the subgroup of progressive midgut NET, with significantly improved median progression-free survival (mPFS). 177Lu-Edotreotide is an innovative radiolabeled SST analogue, with a favourable safety profile and promising efficacy. Retrospective data in metastasized GEP-NET demonstrated a mPFS of 34.5 months. A prospective study of PRRT with an approved comparator has not yet been performed. Here we report the trial design and study objectives comparing the efficacy and safety of 177Lu-Edotreotide with Everolimus. Methods Trial design COMPETE (NCT03049189) is a prospective, randomized, controlled, open-label, multi-center Phase III study to evaluate the efficacy and safety of 177Lu-Edotreotide PRRT compared to Everolimus in patients with inoperable, progressive, SSTR+ GEP-NET. 300 patients with progressive Grade 1 and 2 GEP-NET will be randomized: 200 will receive a maximum of 4 cycles of 177Lu-Edotreotide (7.5 GBq/cycle) every 3 months or until diagnosis of progression; 100 will receive 10 mg Everolimus daily for 24 months, or until diagnosis of progression. Study treatment duration/patient is 24 months. Study Objectives Primary objective is to demonstrate prolonged mPFS in patients in the 177Lu-Edotreotide arm, vs. Everolimus. Secondary objectives include safety, objective response rates and overall survival after treatment with 177Lu-Edotreotide, vs. Everolimus. Conclusion COMPETE is the first pivotal study to compare PRRT in patients with Grade 1 and 2 GEP-NET using a comparator with an approved therapeutic. It is expected that COMPETE will increase their treatment options, including 1st-line therapy. Further studies with 177Lu-Edotreotide in NET patients with high unmet medical need are under review. Citation Format: Mona M. Wahba, Jonathan Strosberg, Anca Avram, Carina Mari Aparici. COMPETE Phase III Trial - Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-Edotreotide vs. Everolimus in Progressive GEP-NET [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT254.

Background This review and meta-analysis examined published evidence of peptide receptor radionuclide therapy (PRRT) re-treatment efficacy and safety in patients with advanced neuroendocrine tumors (NETs). Methods Embase, MEDLINE, MEDLINE In-Progress, and Cochrane CENTRAL were searched (database inception–present) to identify evidence of efficacy and safety of PRRT re-treatment in adults with NETs previously treated with 177Lu- and/or 90Y-PRRT. Progression-free survival (PFS), overall survival (OS), disease control rate (DCR) from time of re-treatment were assessed. Data were pooled using medians and variance for time-to-event outcomes and inverse-variance weighted proportions (Freeman-Tukey method) for binary outcomes. Results Of 567 studies screened, 13 reported re-treatment efficacy outcomes. In random-effects meta-analyses of 177Lu-PRRT re-treatment, median PFS (N = 7 studies [414 patients]) was 12.52 months (95% CI 9.82–15.22) with moderate heterogeneity across studies (I2 = 50.5%), median OS (N = 2 [194 patients]) was 26.78 months (95% CI 18.73–34.83) with moderate-to-high heterogeneity (I2 = 57.5%), and DCR (N = 8 [347 patients]) was 71% (95% CI 66–75) with high heterogeneity (I2 = 81.5%). PFS was similar with either 177Lu-PRRT re-treatment alone or in combination with 90Y-PRRT. Grade 3/4 adverse events occurred in 5% (95% CI 2–8) of patients receiving 177Lu-PRRT re-treatment (N = 5 [271 patients]) with few grade 3/4 renal toxicities (0% [95% CI 0–1]). Pooled myelodysplastic syndrome and acute myeloid leukemia incidence was 0% (95% CI 0–2). Conclusion Re-treatment with 177Lu-PRRT provided encouraging median PFS in patients with NETs with a safety profile similar to initial PRRT.

Treatment options for neuroendocrine tumors (NETs) and carcinomas (NECs) are expanding. Early-phase studies have shown preliminary evidence of the antitumor activity of alpha-emitting peptide receptor radionuclide therapy (PRRT), and novel radiopeptides incorporating somatostatin receptor antagonists (rather than agonists) have been developed. Several tyrosine kinase inhibitors (TKIs) with antiangiogenic potential have been evaluated in patients with NETs, including lenvatinib, axitinib, cabozantinib and pazopanib. Recently, two phase 3 clinical trials have demonstrated the efficacy and safety of surufatinib, an inhibitor of vascular endothelial growth factor receptor (VEGFR)-1, -2, -3, fibroblast growth factor receptor (FGFR)-1 and colony stimulating factor-1 receptor (CSF-1R), in patients with pancreatic and extra-pancreatic NETs. Multiple clinical trials of combination immunotherapy have been recently completed, but interpretation of the results is hampered by small samples sizes and discordant outcomes. This review summarizes recent data on emerging treatments for neuroendocrine neoplasms.

Neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) are a heterogeneous family of neoplasms. Well-differentiated tumors are often slow growing and characterized by low tumor mutational burden. Poorly differentiated NECs are aggressive, with an increased mutational burden and higher propensity to express PD-L1. While the therapeutic landscape for neuroendocrine neoplasms (NENs) has evolved substantially over the past decade, immunotherapy has been unexplored in NENs until recently. Checkpoint inhibitors such as anti-PD-1 and anti-CTLA-4 agents, bi-specific tumor-targeting antibodies, and chimeric antigen receptor (CAR) T-cell therapy are examples of treatments that have demonstrated efficacy in other cancers and have recently been investigated in NENs. This review examines the immune landscape of NENs in detail, summarizes recent clinical study results, and discusses potential future directions for immunotherapy.