Critical appraisal of MGMT in digestive NET treated with alkylating agents

Pancreatic Neuroendocrine Tumors: Signaling Pathways and Epigenetic Regulation

Pancreatic neuroendocrine tumors (PNETs) are characterized by dysregulated signaling pathways that are crucial for tumor formation and progression. The efficacy of traditional therapies is limited, particularly in the treatment of PNETs at an advanced stage. Epigenetic alterations profoundly impact the activity of signaling pathways in cancer development, offering potential opportunities for drug development. There is currently a lack of extensive research on epigenetic regulation in PNETs. To fill this gap, we first summarize major signaling events that are involved in PNET development. Then, we discuss the epigenetic regulation of these signaling pathways in the context of both PNETs and commonly occurring-and therefore more extensively studied-malignancies. Finally, we will offer a perspective on the future research direction of the PNET epigenome and its potential applications in patient care.

Predictive Factors of Response to Streptozotocin in Neuroendocrine Pancreatic Neoplasms

Pancreatic neuroendocrine neoplasms (Pan-NENs) may exhibit a heterogeneous clinical course, ranging from indolent to progressive/metastatic behavior. In the latter scenario, streptozocin (STZ) is considered the cornerstone of systemic treatment; however, response to STZ-based chemotherapy may vary among individuals. In this narrative review, we aimed to identify the predictive factors of response to STZ in advanced Pan-NENs. We performed an extensive search in international online databases for published studies and ongoing clinical trials evaluating STZ in Pan-NENs. We found 11 pertinent studies evaluating 17 patient-, tumor-, or treatment-related factors. Age, CgA blood levels, tumor grade, Ki-67% index, anatomical location of the primary tumor, tumor stage, site of metastasis origin, liver tumor burden, extrahepatic spread, functional status, O6-methylguanine-methyltransferase (MGMT) status, line of therapy, and response to previous treatments were all statistically associated with radiological response and/or survival. The identified predictors may help clinicians make appropriate treatment decisions, in this way improving clinical outcomes in patients with advanced Pan-NENs.

Selection of Chemotherapy in Advanced Poorly Differentiated Extra-Pulmonary Neuroendocrine Carcinoma

Extra-pulmonary poorly differentiated neuroendocrine carcinoma is rare, and evidence for treatment has been limited. In this article, the evidence behind the cytotoxic chemotherapy choices used for metastatic or unresectable EP-PD-NEC is reviewed. In the first-line setting, etoposide and platinum chemotherapy or irinotecan and platinum have been demonstrated to be equivalent in a large phase III trial. Questions remain regarding the optimal number of cycles, mode of delivery, and the precise definition of platinum resistance in this setting. In the second-line setting, FOLFIRI has emerged as an option, with randomized phase 2 trials demonstrating modest, but significant, response rates. Beyond this, data are extremely limited, and several regimens have been used. Heterogeneity in biological behaviour is a major barrier to optimal EP-PD-NEC management. Available data support the potential role of the Ki-67 index as a predictive biomarker for chemotherapy response. A more personalised approach to management in future studies will be essential, and comprehensive multi-omic approaches are required to understand tumour somatic genetic changes in relation to their effects on the surrounding microenvironment.

Integrating Functional Imaging and Molecular Profiling for Optimal Treatment Selection in Neuroendocrine Neoplasms (NEN)

PURPOSE OF REVIEW

Gastroenteropancreatic NEN (GEP-NEN) are group of malignancies with significant clinical, anatomical and molecular heterogeneity. High-grade GEP-NEN in particular present unique management challenges.

RECENT FINDINGS

In the current era, multidisciplinary management with access to a combination of functional imaging and targeted molecular profiling can provide important disease characterisation, guide individualised management and improve patient outcome. Multiple treatment options are now available, and combination and novel therapies are being explored in clinical trials. Precision medicine is highly relevant for a heterogenous disease like NEN. The integration of dual-tracer functional PET/CT imaging, molecular histopathology and genomic data has the potential to be used to gain a more comprehensive understanding of an individual patient's disease biology for precision diagnosis, prognostication and optimal treatment allocation.

FOLFOX-bevacizumab chemotherapy in patients with metastatic neuroendocrine tumors

Neuroendocrine tumors (NETs) are highly vascularized neoplasms. While FOLFOX chemotherapy has shown efficacy in patients with advanced NETs, its combination with antiangiogenics has been scarcely described. Here, we report the efficacy and tolerance of FOLFOX-bevacizumab in this setting. We retrospectively studied all consecutive patients with metastatic NET treated by FOLFOX-bevacizumab in two expert centers from 2013 to 2020. We assessed time to treatment failure (TTF), objective response rate (ORR) and toxicity. We explored factors associated with TTF and ORR using multivariate analyses. We included 57 patients (35.1% female, median age 61.7 years), with pancreatic (66.7%), small-intestine (14%) or lung (7%) NETs. Most patients (57.9%) had extra-hepatic metastases and G3 NETs accounted for 40.3% of cases. Patients received a median of 17 cycles of treatment, including a median of seven cycles of bevacizumab and/or 5-fluorouracile maintenance. Median TTF was 15.5 months (95% CI: 9.8-21.2) and was shorter in patients age > 60 years (HR 2.56, 95% CI: 1.16-5.64), p = .020) and >1 previous systemic treatment line (HR 4.15, 95% CI: 1.96-8.78), p < .001). The ORR was 42.9% and was higher in cases of performance status at 0 (OR 5.25, 95% CI: 1.13-24.35), p = .034) and G3 NET (OR 5.39, 95% CI: 1.23-23.52), p = .025). The FOLFOX-bevacizumab combination has promising efficacy in patients with progressive metastatic NETs and notably for G3 NETs, for which optimal treatment as yet remains ill-defined. Hence, it could be a relevant alternative to alkylating-based chemotherapy in this setting and should be further explored prospectively.

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

Background and Objectives

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

Methods

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

Results

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

Conclusion

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

Molecular deciphering of primary liver neuroendocrine neoplasms confirms its distinct existence with foregut-like profile

Isolated hepatic localizations of neuroendocrine tumors (NETs) are generally considered as metastatic NETs of unknown primary but could correspond to primary hepatic NETs (PHNETs), a poorly explored entity. We aimed to describe the clinicopathological and molecular features of PHNETs and compare them with other primary NETs. We assembled a retrospective cohort of patients managed for hepatic localization of NET without extra-hepatic primary tumor after exhaustive clinical, imaging and immunohistochemical characterization. We performed whole-exome sequencing with mutational and copy number analysis. Transcriptomic profiles were compared to pancreatic (n=31), small-bowel (n=22) and lung (n=15) NETs using principal component analysis, unsupervised clustering and gene-set enrichment analysis. Among 27 screened patients, 16 had PHNET (solitary tumor in 63%, median size 11 cm, G2 NETs in 81%) following clinical and pathological review. DNA analyses showed "foregut-like" genomic profiles with frequent alterations in pathways of Fanconi DNA repair (75%), histone modifiers (58%), adherens junctions (58%) and cell cycle control (50%). The most frequently involved genes were KMT2A (58%), ATM (42%), CDH1, CDKN2C, FANCF and MEN1 (33% each). Transcriptomic analyses showed that PHNETs clustered closer to foregut (pancreatic, lung) NETs than to midgut (small-bowel) NETs, while remaining a distinct entity with specific profile. Assessment of potentially predictive biomarkers suggested efficacy of treatments usually active in foregut NETs. In conclusion, PHNETs display a foregut-like molecular profile distinct from other types of NETs, with recurrent molecular alterations. Upon exhaustive work-up to exclude unrecognized primary tumor, PHNETs should not be considered metastatic NETs from an unknown primary. This article is protected by copyright. All rights reserved.

An update on the development of concepts, diagnostic criteria, and challenging issues for neuroendocrine neoplasms across different digestive organs

Digestive neuroendocrine neoplasms (NENs) are a group of heterogeneous neoplasms found throughout the digestive tract, with different behaviour and genetic background. In the last few years, nomenclature and WHO/UICC classifications of digestive NENs have changed, and molecular classifications have emerged, especially in pancreatic locations. Increasing patho-molecular details are needed to diagnose the different categories of NEN, including the use of helpful immunohistochemical markers. In this review, we address these topics in three successive chapters. We first briefly review recent updates in classifications, discuss important grading and proliferating issues and advances in the molecular understanding of NEN. Then, we provide an update on diagnosis, including the most important differential diagnoses of NEN, with a focus on high-grade neoplasms and mixed tumours. Finally, we highlight a variety of currently used and next-generation predictive and prognostic biomarkers as well as biomarkers of tumour origin and describe some site specificities of gastrointestinal NEN. We specifically focus on biomarkers available to pathologists with the potential to change the way patients with NEN are diagnosed and treated.

Chemotherapy in NEN: still has a role?

Neuroendocrine neoplasms (NENs) comprise a broad spectrum of tumors with widely variable biological and clinical behavior. Primary tumor site, extent of disease, tumor differentiation and expression of so matostatin receptors, proliferation and growth rates are the major prognostic factors that determine the therapeutic strategy. Treatment options for advanced disease have considerably expanded in recent years, particularly for well differentiated tumors (NETs). Novel drugs approved over the past decade in this context include somatostatin analogues and 177Lu-oxodotreotide for somatostatin-receptor-positive gastroenteropancreatic (GEP) NETs, sunitinib for pancreatic NETs (P-NETs), and everolimus for P-NETs and non-functioning lung or gastrointestinal NETs. Nevertheless, chemotherapy remains an essential component of the treatment armamentarium of patients with NENs, particularly of patients with P-NETs or those with bulky, symptomatic or rapidly progressive tumors (generally G3 or high-G2 NENs). In this manuscript we will comprehensively review available evidence related to the use of chemotherapy in lung and GEP NENs and will critically discuss its role in the treatment algorithm of this family of neoplasms.

Molecular Pathology of Well-Differentiated Pulmonary and Thymic Neuroendocrine Tumors: What Do Pathologists Need to Know?

Thoracic (pulmonary and thymic) neuroendocrine tumors are well-differentiated epithelial neuroendocrine neoplasms that are classified into typical and atypical carcinoid tumors based on mitotic index cut offs and presence or absence of necrosis. This classification scheme is of great prognostic value but designed for surgical specimens, only. Deep molecular characterization of thoracic neuroendocrine tumors highlighted their difference with neuroendocrine carcinomas. Neuroendocrine tumors of the lung are characterized by a low mutational burden, and a high prevalence of mutations in chromatin remodeling and histone modification-related genes, whereas mutations in genes frequently altered in neuroendocrine carcinomas are rare. Molecular profiling divided thymic neuroendocrine tumors into three clusters with distinct clinical outcomes and characterized by a different average of copy number instability. Moreover, integrated histopathological, molecular and clinical evidence supports the existence of a grey zone category between neuroendocrine tumors (carcinoid tumors) and neuroendocrine carcinomas. Indeed, cases with well differentiated morphology but mitotic/Ki-67 indexes close to neuroendocrine carcinomas have been increasingly recognized. These are characterized by specific molecular profiles and have an aggressive clinical behavior. Finally, thoracic neuroendocrine tumors may arise in the background of genetic susceptibility, being MEN1 syndrome the well-defined familial form. However, pathologists should be aware of rarer germline variants that are associated with the concurrence of neuroendocrine tumors of the lung or their precursors (such as DIPNECH) with other neoplasms, including but not limited to breast carcinomas. Therefore, genetic counseling for all young patients with thoracic neuroendocrine neoplasia and/or any patient with pathological evidence of neuroendocrine cell hyperplasia-to-neoplasia progression sequence or multifocal disease should be considered.

Usefulness of an immunohistochemical score in advanced pancreatic neuroendocrine tumors treated with CAPTEM or everolimus

BACKGROUND

Pancreatic neuroendocrine tumors are rare neoplasms for which few predictive and/or prognostic biomarkers have been validated. Our previous work suggested the potential of the combined expression of N-myc downstream-regulated gen-1 (NDRG-1), O6-methylguanine DNA methyltransferase (MGMT) and Pleckstrin homology-like domain family A member 3 (PHLDA-3) as prognostic factors for relapse and survival.

METHODS

In this new multicenter study we evaluated immunohistochemistry expression in 76 patients with advanced PanNET who were treated with capecitabine-temozolomide or everolimus. Based on the immunohistochemistry panel, an immunohistochemistry prognostic score (IPS) was developed.

RESULTS

In patients treated with capecitabine and temozolomide, low IPS was an independent prognostic factor for progression-free-survival and overall-survival. Similar findings were observed with highest IPS for overall-survival in patients treated with everolimus.

CONCLUSION

From our knowledge, it is the first time that a simple IPS could be useful to predict outcome for patients with metastatic pancreatic neuroendocrine tumors treated with everolimus or capecitabine and temozolomide.