Heterogeneity of grade 3 gastroenteropancreatic neuroendocrine carcinomas: New insights and treatment implications

A Case of Gastric Neuroendocrine Neoplasm with Mixed Grade: a Distinct Type of "High"-grade Well-Differentiated Neuroendocrine Neoplasm

Grade 3 neuroendocrine tumor (NET G3) is a rare new entity that has recently been introduced in the classification of neuroendocrine neoplasms of the pancreas. It is a well-differentiated form, with a high proliferative activity (Ki67 > 20%), and it represents a category whose prognosis is intermediate between NET G2 and poorly differentiated neuroendocrine carcinoma (NEC G3). In sites other than the pancreas, this new category is by far less coded. Herein is reported a case of NET G3 of the stomach, the 13th described in literature. The patient was a 71-year-old man with a mass in the gastric fundus. Histological examination revealed a neuroendocrine tumor that was mostly composed by areas with conventional well-differentiated features and intermediate proliferative rate (< 20 mitoses/10 HPFs and 7% Ki67); part of the tumor was characterized by increased nuclear atypia, a confluent growth pattern, intermediate mitotic activity, and high Ki67 value (25%). The tumor was studied immunohistochemically and molecularly, and the only alteration that came out was MEN1 gene mutation (Lau584SerfsTer5) in both the high- and low-grade components. According to the actual classification of gastric neuroendocrine neoplasms, this case is labeled as NEC G3 but it should be named NET G3, with a much better prognosis than the former. Overall, both morphological pattern and the Ki67 value should be mentioned in the histological report in cases of high-grade neuroendocrine neoplasms because of its clinical significance in defining the prognosis and for new potential therapeutic approaches.

Open issues on G3 neuroendocrine neoplasms: back to the future

The recent recognition that grade 3 (G3) neuroendocrine neoplasms (NENs) can be divided into two different categories according to the histopathological differentiation, that is G3 neuroendocrine tumors (NETs) and G3 neuroendocrine carcinomas (NECs) has generated a lot of interest concerning not only the diagnosis, but also the differential management of such new group of NENs. However, several issues need to be fully clarified in order to put G3 NETs and G3 NECs in the right place. The aim of this review is to focus on those issues that are still undetermined starting from the current knowledge, evaluating the available evidence and the possible clinical implications.

In Reply

Coriat et al. clarify data about their recently published article on gastroenteropancreatic neuroendocrine carcinomas, specifically as related to the management of grade 3 neuroendocrine tumors.

Advanced neuroendocrine tumours of the small intestine and pancreas: clinical developments, controversies, and future strategies

In this Review, we discuss clinical developments and controversies in the treatment of neuroendocrine tumours (NETs) that are relevant for clinicians and clinical researchers. We describe advances in genetics, blood-based biomarkers, functional imaging, and systemic therapy of advanced NETs and discuss results of recent phase 3 studies, systemic treatment of advanced disease with peptide receptor radionuclide therapy, biotherapy, chemotherapy, and molecularly targeted therapy, and the potential role of immunotherapy in the treatment of NETs. Suggested treatment algorithms for NETs of ileal or jejunal origin and of pancreatic origin are presented.

G3 GEP NENs category: are basic and clinical investigations well integrated?

Gastroenteropancreatic neuroendocrine neoplasms grade 3, all of them with >20% Ki-67, can be heterogeneous on the basis of their morphological features, comprising well and poorly differentiated neoplasms; the former are named tumors and the latter carcinomas. Several papers about gastroenteropancreatic neuroendocrine neoplasms grade 3 heterogeneity have been reporting over the last years by clinicians and pathologists, indicating that the differential diagnosis between named tumors grade 3 and named carcinomas grade 3 may be relevant in defining a different approach in terms of characterization of disease, staging, and treatment. To well define the sub-type of gastroenteropancreatic neuroendocrine neoplasms grade 3 pathologist's expertise in recognizing tumor morphology, immunohistochemical, and molecular techniques were reported remarkable. Although current evidence about grade 3 gastroenteropancreatic neuroendocrine neoplasms heterogeneity is still far from producing validated specific therapies for specific subcategories, the hypotheses generated from the several retrospective analyses published so far on this topic represent solid bases for designing prospective therapeutic clinical trials in homogenous clinical settings.

Huge recurrent gastric neuroendocrine tumor: a second-line chemotherapeutic dilemma

Chemotherapy is considered “state of the art” for the treatment of poorly differentiated neuroendocrine neoplasms. Unfortunately, there is no standard effective post-first-line treatment for relapsing high-grade gastroenteropancreatic neuroendocrine neoplasms. We report the case of a patient with a gastric neuroendocrine carcinoma stage IV, with massive gastrointestinal bleeding at diagnosis. After the first line of platin-based chemotherapy a major tumoral response was documented, but the patient relapsed after 4 months. A second line of chemotherapy treatment was given, with the FOLFOX regimen, and the patient has been free of progression for almost 2 years. There is no second-line standard treatment accepted for this type of carcinoma, but 5-fluorouracil combined with oxaliplatin showed interesting antitumor activity.

Preoperative imaging and pathologic classification for pancreatic neuroendocrine tumors

The management of patients with pancreatic neuroendocrine tumor (PNET), whether hormonally secretory or not, is multidisciplinary and often multimodal. Surgical treatment plays a central role because complete resection is the only potentially curative treatment. The choice of the therapeutic plan for a PNET requires precise localization of the primary tumor (which may sometimes be multiple in case of genetic predisposition), confirmation of the diagnosis of PNET, a search for metastases (mainly hepatic), and identification of the main histoprognostic factors. This update focuses on the WHO 2017 histological classification and recent innovations in the preoperative assessment of PNET using conventional and isotopic imaging. The aim is to not only allow the mapping of primary and metastatic lesions but also to predict tumor aggressiveness.

Clinical and Biomarker Evaluations of Sunitinib in Patients with Grade 3 Digestive Neuroendocrine Neoplasms

BACKGROUND/AIMS

Angiogenesis is extensively developed in well-differentiated pancreatic neuroendocrine tumours (PanNET) where sunitinib was shown to prolong progression-free survival, leading to nationwide approval. However, clinical experience in patients with grade 3 gastroenteropancreatic neuroendocrine neoplasms (GEPNEN-G3) remains limited. This prospective phase II trial evaluated potential predictive biomarkers of sunitinib activity in patients with advanced GEPNEN-G3.

METHODS

Sunitinib was given at a dose of 37.5 mg/day as a continuous daily dosing until progression or unacceptable toxicity. Evaluation of activity was based on RECIST1.1. Safety was evaluated according to NCI-CTCAE v4. Pharmacokinetics of sunitinib and its main active metabolite SU12662 were evaluated. All tumour samples were reviewed histologically for tumour differentiation. PDGFRβ, carbonic anhydrase 9, Ki-67, VEGFR2, and p-AKT were quantified using immunohistochemistry and their expression correlated with response by RECIST1.1.

RESULTS

Thirty-one patients were included and 26 had available histological tissue. Six and 20 patients presented well-differentiated tumours (NET-G3) and neuroendocrine carcinoma (NEC), respectively. Eighteen patients responded to sunitinib (4 experienced partial responses and 14 tumour stabilization). A high p-AKT expression correlated with lower response to sunitinib (OR 0.94, 95% CI 0.89-0.99, p = 0.04). Safety and PK exposure to sunitinib and SU12662 in these patients were consistent with that reported in PanNET.

CONCLUSION

Sunitinib showed evidence of activity in patients with GEPNEN-G3 with expected toxicity profile. In the NET-G3 and NEC groups, 4/6 and 11/20 patients were responders, respectively. High p-AKT expression predicted a lower response to sunitinib. Our study allowed the identification of a potential biomarker of resistance/sensitivity to sunitinib in aggressive GEPNEN-G3.

Downgrading of a G3 Neuroendocrine Tumor to a G2 Tumor: Can First-Line Cytotoxic Chemotherapy Change the Tumor Biology?

The antiproliferative treatment options for neuroendocrine tumors (NET)/neuroendocrine carcinomas of the gastrointestinal tract critically depend on the proliferation rate, evaluated by immunohistochemical staining for Ki-67. According to their grading, tumors are treated with somatostatin analogs, mTOR inhibitors, or cytotoxic substances. This case illustrates downgrading of a primarily highly proliferative NET achieved by a variation of cytotoxic chemotherapy regimens, followed by a combination therapy using everolimus together with lanreotide. The latter medication might lead to a good clinical response as far as tumor growth is concerned.

[Classification of pancreatic neuroendocrine tumours: Changes made in the 2017 WHO classification of tumours of endocrine organs and perspectives for the future]

The WHO classification of the tumors of endocrine organs, published in July 2017, has introduced significant changes in the classification of pancreatic neuroendocrine tumors, the previous version of which has appeared in 2010, within the WHO classification of the tumors of the digestive system. The main change is the introduction of a new category of well-differentiated neoplasms, neuroendocrine tumors G3, in addition to the previous categories of neuroendocrine tumors G1 and G2. The differential diagnosis between neuroendocrine tumors G3 (well-differentiated) and neuroendocrine carcinomas (poorly-differentiated) might be difficult; the authors of the WHO classification therefore suggest the use of a number of immunohistochemical markers to facilitate the distinction between the two entities. The other changes are: (a) the modification of the threshold between neuroendocrine tumors G1 and G2, now set at 3%; (b) the terminology used for mixed tumors: the previous term mixed adeno-neuroendocrine carcinoma (MANEC) is substituted by the term mixed neuroendocrine-non neuroendocrine neoplasm (MiNEN). Finally, the recommendations for Ki-67 index evaluation are actualized. Even if these changes only concern, stricto sensu, the neuroendocrine tumors of pancreatic location, they will probably be applied, de facto, for all digestive neuroendocrine tumors. The revision of the histological classification of pancreatic neuroendocrine tumors coincides with the revision of their UICC TNM staging; significant changes have been made in the criteria for T3 and T4 stages. Our professional practices have to take into account all these modifications.

Increased incidence trend of low-grade and high-grade neuroendocrine neoplasms

PURPOSE

The incidence of neuroendocrine neoplasms is increasing. This work aimed at: (i) establishing worldwide incidence trend of low-grade neuroendocrine neoplasms; (ii) defining the incidence and temporal trend of high-grade neuroendocrine neoplasms in USA utilizing the Surveillance Epidemiology and End Results database; (iii) comparing trends for low-grade vs. high-grade neuroendocrine neoplasms.

METHODS

We conducted a literature search on MEDLINE and Scopus databases and incidence trends were plotted for 1973-2012. The Surveillance Epidemiology and End Results database was used to identify incidence rates in USA for 1973-2012. Incidence rates were stratified according to histological grade, gender and ethnicity. Trends were summarized as annual percent change and corresponding 95% confidence interval.

RESULTS

11 studies were identified involving 72,048 cases; neuroendocrine neoplasm incidence rates increased over time in all countries for all sites, except for appendix. In Surveillance Epidemiology and End Results low-grade neuroendocrine neoplasm incidence rate increased from 1.09 in 1973 to 3.51 per 100,000 in 2012. During this interval, high-grade neuroendocrine neoplasm incidence rate increased from 2.54 to 10.52 per 100,000. African Americans had the highest rates of digestive neuroendocrine neoplasms with male prevalence in high-grade.

CONCLUSIONS

Our data indicate an increase in the incidence of neuroendocrine neoplasms as a worldwide phenomenon, affecting most anatomical sites and involving both low-grade and high-grade neoplasms.

Role of PD-L1 expression as a biomarker for GEP neuroendocrine neoplasm grading

Neuroendocrine neoplasms (NENs) are rare, heterogeneous and ubiquitous tumors commonly localized in the gastrointestinal tract, lung, and pancreas. The clinical behavior of NEN is highly unpredictable; in fact, low-grade cases can unexpectedly be associated with metastases. Currently, the 2010 WHO NEN classification employs histological differentiation and the proliferation index for grading tumors but fails to provide reliable prognostic and therapeutic indications. Therefore, there is an urgent need for a better characterization of G2/G3 NENs. Similar to several other tumors, NENs possess immune-escape mechanisms, but very little has yet been done to characterize this crucial aspect. There are no available data describing PD-L1 expression in these tumors. Here we provide, for the first time, evidence of PD-L1 tissue expression in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). PD-L1 expression was significantly associated with a high-grade WHO classification (G3) (P<0.001) but not with gender, primary site, or lymph node status. The PD-L1 positivity rate and signal intensity are directly correlated (P<0.001) with a grade increase from G1 to G3. In particular in G3 cases, we observed a dichotomy between the morphology (WD- and PD-NENs) and Ki67. Moreover, our study demonstrated a significant association with the grade and PD-L1 expression levels in immune-infiltrating cells (P<0.001). In particular, G3 tumors are characterized by strong PD-L1 expression in both the tumor and infiltrating immune cells (P<0.001), reflecting an unfavorable environment for T-cell-mediated tumor aggression. These findings suggest that NENs might acquire resistance to immune surveillance by upregulating PD-L1 and inhibiting peritumoral and intratumoral infiltrating lymphocytes. Here we demonstrate that PD-L1 is currently the best-known biomarker for G3 NENs, becoming the new gold standard for G3 NEN discrimination. Furthermore, pharmacological approaches using anti-PD-1 antibodies may become the logical choice for the treatment of G3 cases with a poor prognosis.

Different long-term oncologic outcomes after radical surgical resection for neuroendocrine carcinoma and adenocarcinoma of the stomach

PURPOSE

To explore differences in long-term outcomes between gastric neuroendocrine carcinoma (GNEC) and gastric adenocarcinoma (GAC).

METHODS

One hundred GNEC patients and 3089 GAC patients were enrolled. Differences in long-term outcomes between the groups were analyzed by 1:2 propensity score matching.

RESULTS

Statistically significant differences between the groups were noted in terms of gender, American Society of Anesthesiologists score, tumor size, T stage, N stage, TNM stage and surgical approach. However, differences were not significant after matching. The 3-year and 5-year overall survival rates for the GNEC group were reduced compared with those for the GAC group, though disease-free survival rates and mean recurrence times were similar. Notably, the mean post-recurrence survival of the GNEC group was significantly worse than that of the GAC group (5.2 vs. 14.8 months, p<0.001). A strong negative correlation was found between a high Ki-67 labeling index and overall survival time. Cox regression analysis indicated the Ki-67 labeling index to be an independent factor influencing patient post-recurrence survival.

CONCLUSIONS

The long-term oncologic outcome of GNEC was worse than that of GAC, which may be relative to its reduced post-recurrence survival. A high Ki-67 labeling index was an independent factor influencing patient post-recurrence survival.

The Surgical Management of Small Bowel Neuroendocrine Tumors: Consensus Guidelines of the North American Neuroendocrine Tumor Society

Small bowel neuroendocrine tumors (SBNETs) have been increasing in frequency over the past decades, and are now the most common type of small bowel tumor. Consequently, general surgeons and surgical oncologists are seeing more patients with SBNETs in their practices than ever before. The management of these patients is often complex, owing to their secretion of hormones, frequent presentation with advanced disease, and difficulties with making the diagnosis of SBNETs. Despite these issues, even patients with advanced disease can have long-term survival. There are a number of scenarios which commonly arise in SBNET patients where it is difficult to determine the optimal management from the published data. To address these challenges for clinicians, a consensus conference was held assembling experts in the field to review and discuss the available literature and patterns of practice pertaining to specific management issues. This paper summarizes the important elements from these studies and the recommendations of the group for these questions regarding the management of SBNET patients.

Rb Loss and KRAS Mutation Are Predictors of the Response to Platinum-Based Chemotherapy in Pancreatic Neuroendocrine Neoplasm with Grade 3: A Japanese Multicenter Pancreatic NEN-G3 Study

Purpose: Patients with pancreatic neuroendocrine neoplasm grade-3 (PanNEN-G3) show variable responses to platinum-based chemotherapy. Recent studies indicated that PanNEN-G3 includes well-differentiated neuroendocrine tumor with G3 (NET-G3). Here, we examined the clinicopathologic and molecular features of PanNEN-G3 and assessed the responsiveness to chemotherapy and survival.Experimental Design: A total of 100 patients with PanNEN-G3 were collected from 31 institutions, and after central review characteristics of each histologic subtype [NET-G3 vs. pancreatic neuroendocrine carcinoma (NEC-G3)] were analyzed, including clinical, radiological, and molecular features. Factors that correlate with response to chemotherapy and survival were assessed.Results: Seventy patients analyzed included 21 NETs-G3 (30%) and 49 NECs-G3 (70%). NET-G3 showed lower Ki67-labeling index (LI; median 28.5%), no abnormal Rb expression (0%), and no mutated KRAS (0%), whereas NEC-G3 showed higher Ki67-LI (median 80.0%), Rb loss (54.5%), and KRAS mutations (48.7%). Chemotherapy response rate (RR), platinum-based chemotherapy RR, and prognosis differed significantly between NET-G3 and NEC-G3. Chemotherapeutic outcomes were worse in NET-G3 (P < 0.001). When we stratified PanNEN-G3 with Rb and KRAS, PanNENs-G3 with Rb loss and those with mutated KRAS showed significantly higher RRs to platinum-based chemotherapy than those without (Rb loss, 80% vs. normal Rb, 24%, P = 0.006; mutated KRAS, 77% versus wild type, 23%, P = 0.023). Rb was a predictive marker of response to platinum-based chemotherapy even in NEC-G3 (P = 0.035).Conclusions: NET-G3 and NEC-G3 showed distinct clinicopathologic characteristics. Notably, NET-G3 does not respond to platinum-based chemotherapy. Rb and KRAS are promising predictors of response to platinum-based chemotherapy for PanNEN-G3, and Rb for NEC-G3. Clin Cancer Res; 23(16); 4625-32. ©2017 AACR.

Clinicopathological characteristics of biliary neuroendocrine neoplasms: a multicenter study

OBJECTIVES

This study assessed the clinicopathological features, therapeutic approaches, and prognosis of patients with biliary neuroendocrine neoplasm (NENs).

MATERIALS AND METHODS

Multicenter retrospective study of patients with biliary tract NENs in the gallbladder, the extrahepatic bile duct, or the ampulla of Vater between 2005 and 2014.

RESULTS

Total of 43 patients were included in the study. The median age was 62 years (range: 29-84 years) and 58.1% of the patients were male. The tumors occurred in the gallbladder (n = 11), the extrahepatic bile duct (n = 5) or the ampulla of Vater (n = 27). The liver was the most common metastatic site. Based on the 2010 World Health Organization classification, more patients with gallbladder NENs (11/11 (100%)) had neuroendocrine carcinoma G3 than those with NENs in the ampulla of Vater (10/27 (37.1%)). The median progression free survival time (39.3 vs 5.1 months, p = 0.001) and median overall survival time (46.9 vs 7.9 months, p < 0.001) were significantly longer in patients with ampulla of Vater NENs than gallbladder NENs. A 2010 World Health Organization classification of neuroendocrine carcinoma G3 was independently related to poor overall survival (hazard ratio (HR), 27.1; 95% confidence intervals (CI), 2.81-260.68; p = 0.004).

CONCLUSION

The 2010 World Health Organization classification of neuroendocrine carcinoma G3 was the only factor related to poor prognosis in patients with biliary neuroendocrine neoplasms.

Pancreatic Neuroendocrine Neoplasms: Basic Biology, Current Treatment Strategies and Prospects for the Future

Pancreatic neuroendocrine neoplasms (pNENs) are rare tumors accounting for only 1%–2% of all pancreatic tumors. pNENs are pathologically heterogeneous and are categorized into three groups (neuroendocrine tumor: NET G1, NET G2; and neuroendocrine carcinoma: NEC) on the basis of the Ki-67 proliferation index and the mitotic count according to the 2010 World Health Organization (WHO) classification of gastroenteropancreatic NENs. NEC in this classification includes both histologically well-differentiated and poorly differentiated subtypes, and modification of the WHO 2010 classification is under discussion based on genetic and clinical data. Genomic analysis has revealed NETs G1/G2 have genetic alterations in chromatin remodeling genes such as MEN1, DAXX and ATRX, whereas NECs have an inactivation of TP53 and RB1, and these data suggest that different treatment approaches would be required for NET G1/G2 and NEC. While there are promising molecular targeted drugs, such as everolimus or sunitinib, for advanced NET G1/G2, treatment stratification based on appropriate predictive and prognostic biomarkers is becoming an important issue. The clinical outcome of NEC is still dismal, and a more detailed understanding of the genetic background together with preclinical studies to develop new agents, including those already under investigation for small cell lung cancer (SCLC), will be needed to improve the prognosis.