A tale of two tumors: treating pancreatic and extrapancreatic neuroendocrine tumors

Current Status of Immunotherapy in Management of Small Bowel Neuroendocrine Tumors

PURPOSE OF REVIEW

This study aims to present the current landscape of immunotherapy in the management of small bowel neuroendocrine tumors and identify ongoing and future targets for improved response.

RECENT FINDINGS

Somatostatin analogs and mTOR inhibitors remain cornerstones of non-surgical treatment, and applications of PRRT in SBNET are promising. Several efforts to replicate the success of immunotherapies in other solid tumors have been attempted in SBNET, with limited responses observed with current immune targets, such as PD-1/PD-L1 and CTLA-4. Epigenetic analyses have suggested a potential role for methylation and histone acetylation in SBNET tumorigenesis that warrant greater exploration. While the incidence of SBNET continues to increase, the number of effective therapies is few. Further elucidation of targetable components of the SBNET immune microenvironment with greater modulatory effects is necessary to improve outcomes in this growing patient population.

S-1/temozolomide versus S-1/temozolomide plus thalidomide in advanced pancreatic and non-pancreatic neuroendocrine tumours (STEM): A randomised, open-label, multicentre phase 2 trial

BACKGROUND

There are currently limited systemic treatment options for patients with advanced neuroendocrine tumours (NETS) and the efficacy of existing treatments is sub-optimal. We evaluated the efficacy and safety of Tegafur/gimeracil/oteracil/potassium capsules (S-1)/Temozolomide with or without thalidomide for the treatment of NETS (STEM trial).

METHODS

A randomised, controlled, open-label, phase 2 trial conducted at eight hospitals in China. Adults (≥18 years) with unresectable/metastatic, pancreatic or non-pancreatic NETS, with an Eastern Cooperative Oncology Group (ECOG) PS of 0-1, and progression on ≤2 previous therapies were randomised (1:1, using hierarchical block randomization with block length 4, stratified by pancreatic/non-pancreatic disease to receive S-1 40-60 mg orally twice daily on days 1-14 plus temozolomide 200 mg orally daily on days 10-14 in a 21-day cycle OR S-1 and temozolomide plus thalidomide orally nightly (100 mg on days 1-7, 200 mg on days 8-14, and 300 mg from day 15), until disease progression, death, intolerable toxicity, withdrawal of informed consent or at the investigator's discretion. The primary endpoint was objective response rate (ORR) by RECIST 1.1 in an intention-to-treat population. Safety was assessed in all patients who received treatment. The study was registered at ClinicalTrials.gov: NCT03204019 (pancreatic group) and NCT03204032 (non-pancreatic group).

FINDINGS

Between March 23, 2017 and November 16, 2020, 187 patients were screened and 140 were randomly assigned to S-1/temozolomide plus thalidomide (n = 69) or S-1/temozolomide (n =71). After a median follow-up of 12·1 months (IQR: 8·4-16·6), the ORR was comparable in the S-1/temozolomide plus thalidomide and S-1/temozolomide groups 26·1% [95% CI 17·2-37·5] versus 25·4% [95% CI 16·7-36·6]; odds ratio: 1·03 [95% CI 0·48-2·22]; P = 0·9381). In the S-1/temozolomide plus thalidomide group, the most common grade 3-4 treatment-related adverse event was fatigue (2/68, 3%), and in the control group were thrombocytopenia and diarrhea (both 1/71, 2%). There were no treatment-related deaths in either group.

INTERPRETATION

S-1/temozolomide with or without thalidomide leads to a comparable treatment response in patients with advanced/metastatic NETS.

FUNDING

This work was supported by CAMS Innovation Fund for Medical Sciences (CIFMS,2021-I2M-1-066, 2017-I2M-4-002, 2021-I2M-1-019, 2017-I2M-1-001), the National Natural Science Foundation of China (81972311, 82141127, 31970794,), the State Key Project on Infection Diseases of China (2017ZX10201021-007-003), the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (2019PT310026), Sanming Project of Medicine in Shenzhen (SZSM202011010), and the State Key Laboratory Special fund from the Ministry of Science (2060204).

Expression of glucose transporter-2 in murine retina: Evidence for glucose transport from horizontal cells to photoreceptor synapses

The retina has the highest relative energy consumption of any tissue, depending on a steady supply of glucose from the bloodstream. Glucose uptake is mediated by specific transporters whose regulation and expression are critical for the pathogenesis of many diseases, including diabetes and diabetic retinopathy. Here, we used immunofluorescence to show that glucose transporter-2 (GLUT2) is expressed in horizontal cells of the mouse neuroretina in proximity to inner retinal capillaries. To study the function of GLUT2 in the murine retina, we used organotypic retinal explants, cultivated under entirely controlled, serum-free conditions and exposed them to streptozotocin, a cytotoxic drug transported exclusively by GLUT2. Contrary to our expectations, streptozotocin did not measurably affect horizontal cell viability, while it ablated rod and cone photoreceptors in a concentration-dependent manner. Staining for poly-ADP-ribose (PAR) indicated that the detrimental effect of streptozotocin on photoreceptors may be associated with DNA damage. The negative effect of streptozotocin on the viability of rod photoreceptors was counteracted by co-administration of either the inhibitor of connexin-formed hemi-channels meclofenamic acid or the blocker of clathrin-mediated endocytosis dynasore. Remarkably, cone photoreceptors were not protected from streptozotocin-induced degeneration by neither of the two drugs. Overall, these data suggest the existence of a GLUT2-dependent glucose transport shuttle, from horizontal cells into photoreceptor synapses. Moreover, our study points at different glucose uptake mechanisms in rod and cone photoreceptors.

Progress in the Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous and orphan group of neoplasms that vary in their histology, clinical features, prognosis, and management. The treatment of PNETs is highly dependent on the stage at presentation, tumor grade and differentiation, presence of symptoms from hormonal overproduction or from local growth, tumor burden, and rate of progression. The US Food and Drug Administration has recently approved many novel treatments, which have altered decision making and positively impacted the care and prognosis of these patients. In this review, we focus on the significant progress made in the management of PNETs over the past decade, as well as the active areas of research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Drug Development in Neuroendocrine Tumors: What Is on the Horizon?

OPINION STATEMENT

Neuroendocrine neoplasms (NENs) constitute a heterogenous group of malignancies. Translational research into NEN cell biology is the cornerstone for drug development strategies in this field. Somatostatin receptor type 2 (SSTR2) expression is the hallmark of well-differentiated neuroendocrine tumors (NETs). Somatostatin analogs and peptide receptor radionuclide therapy (PRRT) form the basis of anti-SSTR2 treatment onto new combination strategies, antibody-drug conjugates and bispecific antibodies. Classical pathways involved in NET development (PI3K-Akt-mTOR and antiangiogenics) are reviewed but new potential targets for NET treatment will be explored. Epigenetic drugs have shown clinical activity in monotherapy and preclinical combination strategies are more than attractive. Immunotherapy has shown opposite results in different NEN settings. Although the NOTCH pathway has been targeted with disappointing results, new strategies are being developed. Finally, after years of solid preclinical evidence on different genetically engineered oncolytic viruses, clinical trials for refractory NET patients are now ongoing.

Surufatinib in advanced extrapancreatic neuroendocrine tumours (SANET-ep): a randomised, double-blind, placebo-controlled, phase 3 study

BACKGROUND

Therapeutic options for advanced neuroendocrine tumours (NETs) are limited. We investigated the efficacy and safety of surufatinib (HMPL-012, sulfatinib) in patients with extrapancreatic NETs.

METHODS

SANET-ep was a randomised, double-blind, placebo-controlled, phase 3 trial undertaken at 24 hospitals across China. Patients (aged 18 years or older) with unresectable or metastatic, well differentiated, extrapancreatic NETs, with an Eastern Cooperative Oncology Group performance status of 0 or 1, and progression on no more than two types of previous systemic regimens were enrolled. Patients were centrally randomly assigned (2:1) using stratified block randomisation (block size 3) via an interactive web response system to receive oral surufatinib at 300 mg per day or matching placebo. Randomisation was stratified by tumour origin, pathological grade, and previous treatment. Patients, investigators, research staff and the sponsor study team were masked to treatment allocation. Crossover to the surufatinib group was allowed for patients in the placebo group at disease progression. The primary endpoint was investigator-assessed progression-free survival, which was analysed in the intention-to-treat population. A preplanned interim analysis was done at 70% of predicted progression-free survival events. This study was registered with ClinicalTrials.gov, NCT02588170. Follow-up is ongoing.

FINDINGS

Between Dec 9, 2015, and March 31, 2019, 198 patients were randomly assigned to surufatinib (n=129) or placebo (n=69). Median follow-up was 13·8 months (95% CI 11·1-16·7) in the surufatinib group and 16·6 months (9·2-not calculable) in the placebo group. Investigator-assessed median progression-free survival was 9·2 months (95% CI 7·4-11·1) in the surufatinib group versus 3·8 months (3·7-5·7) in the placebo group (hazard ratio 0·33; 95% CI 0·22-0·50; p<0·0001). As the trial met the predefined criteria for early discontinuation of the study at the interim analysis, the study was terminated early, as recommended by the independent data monitoring committee. The most common treatment-related adverse events of grade 3 or worse were hypertension (47 [36%] of 129 patients in the surufatinib group vs nine [13%] of 68 patients in the placebo group) and proteinuria (25 [19%] vs zero). Treatment-related serious adverse events were reported in 32 (25%) of 129 patients in the surufatinib group and nine (13%) of 68 patients in the placebo group. Treatment-related deaths occurred in three patients in the surufatinib group (disseminated intravascular coagulation and hepatic encephalopathy, liver injury, and death with unknown reason) and one patient in the placebo group (cachexia and respiratory failure).

INTERPRETATION

Progression-free survival was significantly longer in patients given surufatinib compared with patients given placebo, and surufatinib has a favourable benefit-to-risk profile in patients with progressive, advanced, well differentiated extrapancreatic NETs. Our results suggest that surufatinib might be a new treatment option for this population.

FUNDING

Hutchison MediPharma.

Glucagonoma: From skin lesions to the neuroendocrine component (Review)

Glucagonoma is a hormonally active rare pancreatic neuroendocrine tumour causing an excess of glucagon. This is a narrative review based on a multidisciplinary approach of the tumour. Typically associated dermatosis is necrolytic migratory erythema (NME) which is most frequently seen at disease onset. Insulin-dependent diabetes mellitus, depression, diarrhoea, deep vein thrombosis are also identified, as parts of so-called 'D' syndrome. Early diagnosis is life saving due to potential aggressive profile and high risk of liver metastasis. NME as paraneoplastic syndrome may be present for months and even years until adequate recognition and therapy; it is remitted after successful pancreatic surgery. Thus the level of practitioners' awareness is essential. If surgery is not curative, debulking techniques may improve the clinical aspects and even the outcome in association with other procedures such as embolization of hepatic metastasis; ablation of radiofrequency type; medical therapy including chemotherapy, targeted therapy with mTOR inhibitors such as everolimus, PRRT (peptide receptor radiotherapy), and somatostatin analogues (including combinations of medical treatments). Increased awareness of the condition involves multidisciplinary practitioners.

Short- and Long-Term Outcomes of Laparoscopic Organ-Sparing Resection for Pancreatic Neuroendocrine Neoplasms

BACKGROUND

Pancreatic neuroendocrine neoplasms (PNENs) are rare neoplasms associated with a long life expectancy after resection. In this setting, patients may benefit from laparoscopic organ-sparing resection. Studies of laparoscopic organ-sparing resection for PNENs are limited. The aim of this study was to evaluate the short- and long-term outcomes of laparoscopic organ-sparing resection for PNENs.

METHODS

A retrospective study was performed for patients with PNENs who underwent laparoscopic organ-sparing pancreatectomy between March 2005 and May 2018. The patients' demographic data, operative results, pathological reports, hospital courses and morbidity, mortality, and follow-up data (until August 2018) were analysed.

RESULTS

Thirty-five patients were included in the final analysis. There were 9 male and 26 female patients, with a median age of 46 years (range 25-75 years). The mean BMI was 24.6 ± 3.3 kg/m². Nine patients received laparoscopic enucleation (LE), 20 received laparoscopic spleen-preserving distal pancreatectomy (LSPDP), and 6 received laparoscopic central pancreatectomy. The operative time, intraoperative blood loss, transfusion rate, and postoperative hospital stay were 186.4 ± 60.2 min, 165 ± 73.0 ml, 0 days, and 9 days (range 5-23 days), respectively. The morbidity rate, grade ≥ III complication rate, and grade ≥ B pancreatic fistula rate were 34.2%, 11.4%, and 8.7%, respectively, with no mortality. The rate of follow-up was 94.3%, and the median follow-up time was 55 months (range 3-158 months). One patient developed recurrence 36 months after LE and was managed with surgical resection. The other patients survived without metastases or recurrence during the follow-up. One patient had diabetes after LSPDP, and no patients had symptoms of pancreatic exocrine insufficiency. Nineteen patients who underwent LSPDP (16 with the Kimura technique and 3 with the Warshaw technique) were followed. Normal patency of the splenic artery and vein was observed in 14 and 14 patients within 1 month of surgery and in 15 and 14 patients 6 months or more after the operation, respectively. Partial splenic infarction was observed in 3 patients within 1 month of surgery and in no patients 6 months or more after the operation. Three patients eventually developed collateral venous vessels around the gastric fundus and reserved spleen, with one case of variceal bleeding.

CONCLUSIONS

Laparoscopic organ-sparing resection for selected cases of PNENs is safe and feasible and has favourable short- and long-term outcomes.

Insulinoma Presenting as a Complex Partial Seizure: Still a Possible Misleading Factor

Delayed diagnosis of insulinoma remains an intractable clinical challenge because the symptoms are in most cases misattributed to other disorders. In this study, a 64-year-old man presented with intermittent seizure episodes after being misdiagnosed with epilepsy and receiving anti-epileptic drugs for 4 years. During this period, the patient continued to suffer from repeated seizures. A starvation test, pancreatic enhancement CT, MRI scan, and pathological examination clinically diagnosed insulinoma, and the symptoms improved following surgical removal of the tumor. The appearance of unusual manifestations and insulinoma imaging makes it difficult to accurately diagnose the condition. This case emphasizes the need for careful reassessment of all atypical and refractory seizures for neurologists.

Spleen-preserving distal pancreatectomy and lymphadenectomy for glucagonoma syndrome: A case report

RATIONALE

Glucagonoma is a rare type of functional pancreatic neuroendocrine tumor that is characterized by distinctive clinical manifestations; among these, necrolytic migratory erythema represents the hallmark clinical sign of glucagonoma syndrome and is usually presented as the initial complaint of patients.

PATIENT CONCERNS

A 30-year-old male patient was admitted to our hospital with a complaint of diffuse erythematous ulcerating skin rash for more than 10 months. He also complained of hyperglycemia and a weight loss of 15 kg in those months.

DIAGNOSIS

This patient underwent a contrast-enhanced computed tomography scan which showed a pancreatic body mass measuring approximately 6 cm with low density accompanied by partial calcification in plain scanning images and uneven enhancement in strengthening periods. In addition, laboratory tests indicated elevated fasting blood glucagon (1109 pg/mL, normal range: 50-150 pg/mL) levels. Glucagonoma syndrome was ultimately diagnosed in clinical.

INTERVENTION

Spleen-preserving distal pancreatectomy was conducted and postoperative pathology revealed the presence of glucagonoma.

OUTCOMES

The patient recovered uneventfully with the glucagonoma syndrome disappeared soon after surgery, and the postoperative plasma glucagon decreased to a normal level. Follow-up showed no recurrence for 5 years since the surgery.

LESSONS

The treatment of glucagonoma should be directed according to the stage at which the disease is diagnosed. Surgery is currently the only method available to cure the tumor, although medications are given to patients who present with advanced glucagonoma and who are not candidates for operation. Multidisciplinary therapy and multimodality treatment are advised, although these have been systematically evaluated to a lesser degree.

Surgical management of Zollinger-Ellison syndrome: Classical considerations and current controversies

Zollinger-Ellison syndrome (ZES) is characterized by gastric acid hypersecretion causing severe recurrent acid-related peptic disease. Excessive secretion of gastrin can now be effectively controlled with powerful proton pump inhibitors, but surgical management to control gastrinoma itself remains controversial. Based on a thorough literature review, we design a surgical algorithm for ZES and list some significant consensus findings and recommendations: (1) For sporadic ZES, surgery should be routinely undertaken as early as possible not only for patients with a precisely localized diagnosis but also for those with negative imaging findings. The surgical approach for sporadic ZES depends on the lesion location (including the duodenum, pancreas, lymph nodes, hepatobiliary tract, stomach, and some extremely rare sites such as the ovaries, heart, omentum, and jejunum). Intraoperative liver exploration and lymphadenectomy should be routinely performed; (2) For multiple endocrine neoplasia type 1-related ZES (MEN1/ZES), surgery should not be performed routinely except for lesions > 2 cm. An attempt to perform radical resection (pancreaticoduodenectomy followed by lymphadenectomy) can be made. The ameliorating effect of parathyroid surgery should be considered, and parathyroidectomy should be performed first before any abdominal surgery for ZES; and (3) For hepatic metastatic disease, hepatic resection should be routinely performed. Currently, liver transplantation is still considered an investigational therapeutic approach for ZES. Well-designed prospective studies are desperately needed to further verify and modify the current considerations.

Surufatinib in Advanced Well-Differentiated Neuroendocrine Tumors: A Multicenter, Single-Arm, Open-Label, Phase Ib/II Trial

PURPOSE

No antiangiogenic treatment is yet approved for extrapancreatic neuroendocrine tumors (NET). Surufatinib (HMPL-012, previously named sulfatinib) is a small-molecule inhibitor targeting vascular endothelial growth factor receptors, fibroblast growth factor receptor 1 and colony-stimulating factor 1 receptor. We conducted a single-arm phase Ib/II study of surufatinib in advanced NETs.

PATIENTS AND METHODS

Patients with histologically well-differentiated, low or intermittent grade, inoperable or metastatic NETs were enrolled into a pancreatic or extrapancreatic NET cohort. Patients were treated with surufatinib 300 mg orally, once daily. The primary endpoints were safety and objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors (version 1.1).

RESULTS

Of the 81 patients enrolled, 42 had pancreatic NETs and 39 had extrapancreatic NETs. Most patients had radiologic progression within 1 year prior to enrollment (32 patients in each cohort). In the pancreatic and extrapancreatic NET cohorts, ORRs were 19% [95% confidence intervals (CI), 9-34] and 15% (95% CI, 6-31), disease control rates were 91% (95% CI, 77-97) and 92% (95% CI, 79-98), and median progression-free survival was 21.2 months (95% CI, 15.9-24.8) and 13.4 months (95% CI, 7.6-19.3), respectively. The most common grade ≥3 treatment-related adverse events were hypertension (33%), proteinuria (12%), hyperuricemia (10%), hypertriglyceridemia, and diarrhea (6% for each), and increased alanine aminotransferase (5%).

CONCLUSIONS

Surufatinib showed encouraging antitumor activity and manageable toxicities in patients with advanced NETs. Two ongoing phase III studies, validating the efficacy of surufatinib in patients with NETs, will contribute to the clinical evidence.

Long-Term Survival and Glycemic Control with Toceranib Phosphate and Prednisone for a Metastatic Canine Insulinoma

Canine insulinoma is a highly metastatic neoplasm that is associated with a guarded to poor prognosis in dogs with distant metastases. A median survival of 6 mo has been reported for dogs with metastatic insulinoma. The dog in this report, diagnosed with stage III pancreatic insulinoma, had long-term glycemic control with survival of over 24 mo while receiving prednisone and toceranib phosphate after partial pancreatectomy. Toceranib phosphate has been shown to be an efficacious therapy for canine mast cell tumors with increasing evidence that it may be beneficial in the medical management of neuroendocrine tumors.

A meta-analysis of Prognostic factor of Pancreatic neuroendocrine neoplasms

Pancreatic neuroendocrine neoplasms (pNENs) are a group of clinically rare and heterogeneous diseases of the pancreas. However, the prognostic factors for this disease in patients still remain controversial. The purpose of our study is to evaluate the predictive roles of those prognostic factors for pNENs. All related articles published until Sep 17, 2017 were identified via PubMed, EMBASE, Web of Science, Ovid and the Cochrane Library. Studies that examined the prognostic factors of pNENs were enrolled. 17 articles (2822 patients) were finally included in this study. The pooled data suggested that patients with positive surgical resection margin and lymph node, advanced G stage and TMN stage, organ metastasis, vascular invasion and the necrosis of specimens had a decreased overall survival for pNENs. Similarly, patients with functional tumors might have a poor prognosis. However, age, gender, surgical type and size of tumor could not be regarded as prognostic factors for pNENs. Our analytic data demonstrated that surgical resection margin, G stage, TMN stage, lymph node, metastasis, vascular invasion and the necrosis could be prognostic factors for pNENs. Our study may assist doctors to screen patients with different prognosis more efficiently during follow-up and select appropriate treatment measures.

A single institution's 21-year experience with surgically resected pancreatic neuroendocrine tumors: an analysis of survival and prognostic factors

BACKGROUND

Pancreatic neuroendocrine tumors (pNETs) comprise a heterogeneous group of tumors with a varied biological behavior. In the present study, we analyzed the experience of 79 pNETs resected between 1999 and 2014. The pathologic prognostic factors (European Neuroendocrine Tumor Society, ENETS; and AJCC) classification, vascular invasion (VI), proliferation index (ki-67) and the presence of necrosis were retrospectively reviewed.

METHODS

The clinical data of 79 patients with pNETs who underwent surgery were retrospectively analyzed. Mortality rates and Kaplan-Meier estimates were used to evaluate survival over time for pathologic stages, tumor functionality, and vascular invasion. Cox proportional hazards models were used to calculate the hazard ratio regarding ENETS, AJCC staging, sex, tumor functionality and vascular invasion.

RESULTS

The male:female ratio was 40:39. Twenty-one patients (26%) had functional tumors and 58 (73.4%) had non-functional tumors, of which 35 (44.3%) were diagnosed incidentally. Seventeen Whipple procedures, 46 distal pancreatectomies (including 26 laparoscopic and 20 open procedures), 8 laparoscopic central pancreatectomies, 1 laparoscopic resection of the uncinated process and 7 enucleations (one laparoscopic) were performed. Vascular invasion and necrosis were observed in 29 of 75 cases (38.6%) and in 16 cases (29%), respectively. The comparison between survivor functions of ENETS staging categories showed statistically significant differences (p = 0.042). Mortality rate was higher in patients with non-functioning tumors compared with hormonally functioning tumors (p = 0.052) and in those with vascular invasion (p = 0.186).

CONCLUSIONS

In spite of the heterogeneity of pNETs, the ENETS TNM classification efficiently predicts long-term prognosis. The non-functioning tumors and the presence of vascular invasion are associated with poor prognosis.

Long-term follow-up and role of FDG PET in advanced pancreatic neuroendocrine patients treated with 177Lu-D OTATATE

PURPOSE

Lu-DOTATATE (Lu-PRRT) is a valid therapeutic option in differentiated pancreatic neuroendocrine tumors (P-NETs). FDG PET seems to be an important prognostic factor in P-NETs. We evaluated the efficacy of Lu-PRRT and the role of FDG PET in 60 patients with advanced P-NETs.

METHODS

From March 2008 to June 2011, 60 consecutive patients with P-NETs were enrolled in the study. Follow-up lasted until March 2016. Eligible patients were treated with two different total cumulative activities (18.5 or 27.8 GBq in 5 cycles every 6-8 weeks), according to kidney and bone marrow parameters.

RESULTS

Twenty-eight patients received a mean full activity (FA) of 25.9 GBq and 32 a mean reduced activity (RA) of 18.5 GBq. The disease control rate (DCR), defined as the sum of CR+PR+SD was 85.7 % in the FA group and 78.1 % in the RA group. Median progression-free survival (mPFS) was 53.4 months in the FA group and 21.7 months in the RA group (P = 0.353). Median overall survival (mOS) was not reached (nr) in FA patients and was 63.8 months in the RA group (P = 0.007). Fifty-five patients underwent an FDG PET scan before Lu-PRRT, 32 (58 %) showing an increased FDG uptake in tumor sites. mPFS was 21.1 months in FDG PET-positive patients and 68.7 months in the FDG PET-negative group (P < 0.0002), regardless of the total activity administered.

CONCLUSION

Both FA and RA are active in patients undergoing Lu-PRRT. However, an FA of 27.8 GBq of Lu-PRRT prolongs PFS and OS compared to an RA of 18.5 GBq. Our results indicate that FDG PET is an independent prognostic factor in this patient setting.

A Delphic consensus assessment: imaging and biomarkers in gastroenteropancreatic neuroendocrine tumor disease management

The complexity of the clinical management of neuroendocrine neoplasia (NEN) is exacerbated by limitations in imaging modalities and a paucity of clinically useful biomarkers. Limitations in currently available imaging modalities reflect difficulties in measuring an intrinsically indolent disease, resolution inadequacies and inter-/intra-facility device variability and that RECIST (Response Evaluation Criteria in Solid Tumors) criteria are not optimal for NEN. Limitations of currently used biomarkers are that they are secretory biomarkers (chromogranin A, serotonin, neuron-specific enolase and pancreastatin); monoanalyte measurements; and lack sensitivity, specificity and predictive capacity. None of them meet the NIH metrics for clinical usage. A multinational, multidisciplinary Delphi consensus meeting of NEN experts (n = 33) assessed current imaging strategies and biomarkers in NEN management. Consensus (>75%) was achieved for 78% of the 142 questions. The panel concluded that morphological imaging has a diagnostic value. However, both imaging and current single-analyte biomarkers exhibit substantial limitations in measuring the disease status and predicting the therapeutic efficacy. RECIST remains suboptimal as a metric. A critical unmet need is the development of a clinico-biological tool to provide enhanced information regarding precise disease status and treatment response. The group considered that circulating RNA was better than current general NEN biomarkers and preliminary clinical data were considered promising. It was resolved that circulating multianalyte mRNA (NETest) had clinical utility in both diagnosis and monitoring disease status and therapeutic efficacy. Overall, it was concluded that a combination of tumor spatial and functional imaging with circulating transcripts (mRNA) would represent the future strategy for real-time monitoring of disease progress and therapeutic efficacy.

Efficacy and Safety of Everolimus in Extrapancreatic Neuroendocrine Tumor: A Comprehensive Review of Literature

BACKGROUND

Everolimus, an oral mTOR (mammalian target of rapamycin) inhibitor, is currently approved for the treatment of progressive pancreatic neuroendocrine tumors (NETs). Although promising, only scattered data, often from nondedicated studies, are available for extrapancreatic NETs.

PATIENTS AND METHODS

A systematic review of the published data was performed concerning the use of everolimus in extrapancreatic NET, with the aim of summarizing the current knowledge on its efficacy and tolerability. Moreover, the usefulness of everolimus was evaluated according to the different sites of the primary.

RESULTS

The present study included 22 different publications, including 874 patients and 456 extrapancreatic NETs treated with everolimus. Nine different primary sites of extrapancreatic NETs were found. The median progression-free survival ranged from 12.0 to 29.9 months. The median time to progression was not reached in a phase II prospective study, and the interval to progression ranged from 12 to 36 months in 5 clinical cases. Objective responses were observed in 7 prospective studies, 2 retrospective studies, and 2 case reports. Stabilization of the disease was obtained in a high rate of patients, ranging from 67.4% to 100%. The toxicity of everolimus in extrapancreatic NETs is consistent with the known safety profile of the drug. Most adverse events were either grade 1 or 2 and easy manageable with a dose reduction or temporary interruption and only rarely requiring discontinuation.

CONCLUSION

Treatment with everolimus in patients with extrapancreatic NETs appears to be a promising strategy that is safe and well tolerated. The use of this emerging opportunity needs to be validated with clinical trials specifically designed on this topic.

IMPLICATIONS FOR PRACTICE

The present study reviewed all the available published data concerning the use of everolimus in 456 extrapancreatic neuroendocrine tumors (NETs) and summarized the current knowledge on the efficacy and safety of this drug, not yet approved except for pancreatic NETs. The progression-free survival rates and some objective responses seem promising and support the extension of the use of this drug. The site-by-site analysis seems to suggest that some subtypes of NETs, such as colorectal, could be more sensitive to everolimus than other primary NETs. No severe adverse events were usually reported and discontinuation was rarely required; thus, everolimus should be considered a valid therapeutic option for extrapancreatic NETs.

[177Lu-DOTA0,Tyr3]-octreotate in the treatment of midgut neuroendocrine tumors

Midgut neuroendocrine tumors (NETs) are relatively rare and remarkably heterogeneous. Although recent developments for pancreatic NETs have brought multiple new therapies to patients who need them, there has been little observed efficacy against midgut NETs. Peptide receptor radionuclide therapy utilizes somatostatin analogs conjugated to radioactive isotopes in order to deliver high doses of radiation directly to tumor cells, which express somatostatin receptors. Peptide receptor radionuclide therapy with [(177)Lu-DOTA(0),Tyr(3)]-octreotate (DOTATATE) has been reported and investigated for more than a decade, and the randomized controlled NETTER-1 study of this agent has recently been reported to show promising results. In this article, we will summarize and evaluate the rationale and existing clinical data for the activity of DOTATATE in midgut NETs, to give context for the interpretation of NETTER-1 results when they are fully available.

Igf-I influences everolimus activity in medullary thyroid carcinoma

CONTEXT

Medullary thyroid carcinoma (MTC) is a rare tumor originating from thyroid parafollicular C cells. It has been previously demonstrated that insulin-like growth factor I (IGF-I) protects MTC from the effects of antiproliferative drugs. Everolimus, an mTOR inhibitor, has shown potent antiproliferative effects in a human MTC cell line, TT, and in two human MTC primary cultures.

OBJECTIVE

To verify whether IGF-I may influence the effects of everolimus in a group of human MTC primary cultures.

DESIGN

We collected 18 MTCs that were dispersed in primary cultures, treated without or with 10 nM-1 μM everolimus and/or 50 nM IGF-I. Cell viability was evaluated after 48 h, and calcitonin (CT) secretion was assessed after a 6 h incubation. IGF-I receptor downstream signaling protein expression profile was also investigated.

RESULTS

Everolimus significantly reduced cell viability in eight MTC [by ~20%; P < 0.01 vs. control; everolimus-responders (E-R) MTCs], while cell viability did not change in 10 MTCs [everolimus-non-responders (E-NR) MTCs]. In E-R MTCs, IGF-I blocked the antiproliferative effects of everolimus that did not affect CT secretion, but blocked the stimulatory effects of IGF-I on this parameter. IGF-I receptor downstream signaling proteins were expressed at higher levels in E-NR MTC as compared to E-R MTCs.

CONCLUSION

IGF-I protects a subset of MTC primary cultures from the antiproliferative effects of everolimus and stimulates CT secretion by an mTOR mediated pathway that, in turn, may represent a therapeutic target in the treatment of aggressive MTCs.