Correlation between MGMT promoter methylation and response to temozolomide-based therapy in neuroendocrine neoplasms: an observational retrospective multicenter study

Challenges and future perspectives for the use of temozolomide in the treatment of SCLC

Small-cell lung cancer (SCLC), accounting for 10-20 % of all lung tumors, represents the most aggressive high-grade neuroendocrine carcinoma. Most patients are diagnosed with extensive-stage SCLC (ES-SCLC), with brian metastases identified in ∼ 80 % of cases during the disease cours, and the prognosis is dismal, with a 5-year survival rate of less than 5 %. Current available treatments in the second-line setting are limited, and topotecan has long been the only FDA-approved drug in relapsed or refractory ES-SCLC, until the recent approval of lurbinectedin, a selective inhibitor of RNA polymerase II. Temozolomide (TMZ) is an oral alkylating agent, which showed single-agent activity in SCLC, particularly among patients with O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation. Several studies have revealed the synergistic activity of temozolomide with poly-ADP-ribose polymerase (PARP) inhibitors, that prevent repair of TMZ-induced DNA damage. This review focuses on the rationale for the use of TMZ in ES-SCLC and provides an overview of the main trials that have evaluated and are currently investigating its role, both as a single-agent and in combinations, in relapse or refractory disease.

Efficacy and safety of temozolomide-based regimens in advanced pancreatic neuroendocrine tumors: a systematic review and meta-analysis

BACKGROUND

Recent advances in the management of pancreatic neuroendocrine tumors (pNETs) highlight the potential benefits of temozolomide, an alkylating agent, for these patients. In this meta-analysis, we aimed to assess the outcome of temozolomide, alone or in combination with other anticancer medications in patients with advanced pNET.

METHODS

Online databases of PubMed, Web of Science, Embase, the Cochrane Library, and ClinicalTrials.gov were searched systematically for clinical trials that reported the efficacy and safety of temozolomide in patients with advanced pNET. Random-effect model was utilized to estimate pooled rates of outcomes based on Response Evaluation Criteria in Solid Tumors criteria, biochemical response, and adverse events (AEs).

RESULTS

A total of 14 studies, providing details of 441 individuals with advanced pNET, were included. The quantitative analyses showed a pooled objective response rate (ORR) of 41.2% (95% confidence interval, CI, of 32.4%-50.6%), disease control rate (DCR) of 85.3% (95% CI of 74.9%-91.9%), and a more than 50% decrease from baseline chromogranin A levels of 44.9% (95% CI of 31.6%-49.0%). Regarding safety, the results showed that the pooled rates of nonserious AEs and serious AEs were 93.8% (95% CI of 88.3%-96.8%) and 23.7% (95% CI of 12.0%-41.5%), respectively. The main severe AEs encompassed hematological toxicities.

CONCLUSIONS

In conclusion, our meta-analysis suggests that treatment with temozolomide, either as a monotherapy or in combination with other anticancer treatments might be an effective and relatively safe option for patients with advanced locally unresectable and metastatic pNET. However, additional clinical trials are required to further strengthen these findings. This study has been registered in PROSPERO (CRD42023409280).

Expression of neuroendocrine markers predicts increased survival in triple-negative breast cancer patients

Background

The significance of neuroendocrine (NE) markers in triple-negative breast cancer (TNBC) patients has not been investigated. This study aims to clarify the incidence and prognostic significance of NE marker expression in TNBC, determine its association with other clinicopathological parameters, and further explore the pathological features and potential treatment options for TNBC patients expressing NE markers.

Methods

Clinicopathological data were collected from 396 TNBC patients undergoing radical breast cancer surgery at Peking Union Medical College Hospital from January 2002 to December 2014, with a final follow-up in July 2019. Immunohistochemistry (IHC) staining was performed for NE markers including chromogranin A (CgA) and synaptophysin (Syn). For TNBC patients with positive NE marker expression, IHC staining was then performed for alpha-thalassemia/mental retardation X-linked (ATRX), O(6)-methylguanine-methyltransferase (MGMT), somatostatin receptor 2 (SSTR2), and programmed death receptor-ligand 1 (PD-L1). The chi-square or Fisher exact test was used to evaluate the correlations between NE marker expression and other parameters. Survival curves were plotted using the Kaplan-Meier (K-M) method to assess the prognostic significance of NE markers in TNBC.

Results

NE marker-positive staining was observed in 7.6% (30/396) of all TNBC cases. Only 0.5% (2/396) cases had ≥ 90% neoplastic cells expressing NE markers. Positive NE marker expression was associated with negative basal-like marker expression. K-M survival analysis showed that the NE marker-positive TNBC patients had higher disease-free survival (DFS) rates than the NE marker-negative patients at the same stage. Among the 30 NE marker-positive TNBC cases, 13.3% and 26.7% showed negative IHC staining for ATRX and MGMT, respectively, while 13.3% had a 3+ score for SSTR2 IHC staining. For PD-L1 IHC staining, 13.3% of the 30 TNBC cases were higher than 10 scores in Combined Positive Score (CPS), and 10.0% were higher than 10% in Tumor Cell Proportion Score (TPS).

Conclusion

There was a small proportion of TNBC patients expressing NE markers. TNBC patients with positive NE marker expression had a better prognosis than the negative group at the same stage. TNBC cases with positive NE marker expression may potentially benefit from immunotherapy or somatostatin analogue treatment.

Bronchial carcinoid tumors in children and adolescents - A report and management considerations from the German MET studies

OBJECTIVES

Bronchial carcinoid tumors (BC) are exceptionally rare in childhood, with an incidence of <0.2/1,000,000 per year. Typical low-grade BCs are distinguished from atypical, intermediate-grade BCs. Little is known about BCs in pediatric patients and management guidelines are missing. In this study, we explored characteristics and outcome of pediatric patients with BC prospectively registered with the Malignant Endocrine Tumor studies.

MATERIAL AND METHODS

We performed a retrospective multicenter study in children, adolescents, and young adults (aged 0-20 years) with BC reported to the German MET registry between January 1997 and December 2022. Data were last updated on 28 of February 2023.

RESULTS

Thirty-two patients were diagnosed at a median age of 15.0 years (range, 9.8-19.2). Atypical BCs (23.3%) were less frequent than typical, but more common than in adulthood. Lymph node metastases were present in 14.3% of cases (atypical BC: 28.6%, typical BC: 10.5%), distant metastases in one (3.1%) patient with atypical BC. 92.6% of patients were in complete remission after surgical resection (median follow-up: 2.7 years). The patient with metastatic spread and one patient with atypical BC and multiple recurrences were on treatment at last follow-up. 5-year event-free survival of typical BC was 100% and 83.3% in atypical BC.

CONCLUSIONS

Completely resected localized BCs in pediatric patients have a favorable outcome also with lung tissue sparing surgery. Atypical BC with risk of metastatic spread and recurrence occurred more frequently compared to adults. Interdisciplinary management and collaborative efforts are needed to improve our understanding and the management of pediatric BC.

ERCC1 and MGMT Methylation as a Predictive Marker of Relapse and FOLFOX Response in Colorectal Cancer Patients from South Tunisia

Genetic and epigenetic modifications present a major cause of relapse and treatment failure in colorectal cancer. This study aims to appreciate the prognostic and predictive value of ERRC1 and MGMT methylation. We also studied the prognostic impact of the ERCC1 rs11615 polymorphism as well as its expression. Methylation profiles of ERCC1 and MGMT were tested by methylation-specific PCR. A polymorphism of ERCC1 was studied using PCR-RFLP and its expression was examined by immunohistochemistry. ERCC1 was methylated in 44.6% of colorectal adenocarcinoma while MGMT was methylated in 69% of cases. MGMT methylation was strongly associated with lymph node metastasis, lymph invasion, venous invasion, perineural invasion, distant metastasis and relapse. Patients with methylation of both genes were more likely to have a poor prognosis and display chemoresistance. IHC analysis revealed that ERCC1 staining was noted in 52.8% of colorectal adenocarcinoma and inversely related to distant metastasis and cancer recurrence. Kaplan Meier analysis revealed that the worst overall survival was significantly associated with ERCC1 and MGMT methylation while decreased ERCC1 expression and T/T genotype exhibited the best overall survival. The methylation of MGMT, alone or combined with ERCC1, is predictive for poor prognosis, short overall survival and chemotherapy response in colorectal cancer.

MGMT is frequently inactivated in pancreatic NET-G2 and is associated with the therapeutic activity of STZ-based regimens

O6-methylguanine-DNA methyltransferase (MGMT) has been linked with alkylating agent resistance and tumor growth suppression. However, its role remains undetermined in pancreatic neuroendocrine tumors (Pan-NET). The MGMT expression was examined by immunohistochemistry in 142 patients to evaluate MGMT immunoreactivity and clinicopathological factors. We analyzed the relationship between MGMT expression and treatment efficacy in 19 patients who received STZ-based regimens. In 142 Pan-NET, 97 cases (68.3%) were judged as MGMT-positive and 45 cases (31.6%) as negative. MGMT negativity was significantly more common in NET-G2 (62.5%) than in NET-G1 (11.2%, p < 0.001). MGMT-negative cases were associated significantly with larger tumor size (p < 0.01), higher Ki-67 index (p < 0.01), higher mitotic index (p < 0.05), and more frequent liver metastasis (p < 0.05). Of the 19 cases treated with STZ, 6 cases were determined as SD and 4 cases as PD in MGMT-positive patients (N = 10), while 5 cases were determined as PR and 4 cases as SD in MGMT-negative patients (N = 9). Progression-free survival in MGMT-negative cases was significantly better than in MGMT-positive cases (p < 0.05). MGMT expression was lower in NET-G2 than in NET-G1, and STZ-based regimens improved the therapeutic outcomes of MGMT-negative Pan-NET. These findings indicate that NET-G2 may represent a better therapeutic target for STZ treatment.

Targeted Genomic Profiling and Chemotherapy Outcomes in Grade 3 Gastro-Entero-Pancreatic Neuroendocrine Tumors (G3 GEP-NET)

BACKGROUND

Grade 3 gastro-entero-pancreatic neuroendocrine tumors (G3 GEP-NET) are poorly characterized in terms of molecular features and response to treatments.

METHODS

Patients with G3 GEP-NET were included if they received capecitabine and temozolomide (CAPTEM) or oxaliplatin with either 5-fluorouracile (FOLFOX) or capecitabine (XELOX) as first-line treatment (chemotherapy cohort). G3 NET which successfully undergone next-generation sequencing (NGS) were included in the NGS cohort.

RESULTS

In total, 49 patients were included in the chemotherapy cohort: 15 received CAPTEM and 34 received FOLFOX/XELOX. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were 42.9%, 9.0 months, and 33.6 months, respectively. Calculating a Ki67 cutoff using ROC curve analysis, tumors with Ki67 ≥ 40% had lower ORR (51.2% vs. 0%; p = 0.007) and shorter PFS (10.6 months vs. 4.4 months; p < 0.001) and OS (49.4 months vs. 10.0 months; p = 0.023). In patients who received FOLFOX/XELOX as a first-line treatment, ORR, PFS, and OS were 38.2%, 7.9 months, and 30.0 months, respectively. In the NGS cohort (N = 13), the most mutated genes were DAXX/ATRX (N = 5, 38%), MEN1 (N = 4, 31%), TP53 (N = 4, 31%), AKT1 (N = 2, 15%), and PIK3CA (N = 1, 8%).

CONCLUSIONS

FOLFOX/XELOX chemotherapy is active as the first-line treatment of patients with G3 GEP-NET. The mutational landscape of G3 NET is more similar to well-differentiated NETs than NECs.

Molecular Pathways Implicated in Radioresistance of Glioblastoma Multiforme: What Is the Role of Extracellular Vesicles?

Glioblastoma multiforme (GBM) is a primary brain tumor that is very aggressive, resistant to treatment, and characterized by a high degree of anaplasia and proliferation. Routine treatment includes ablative surgery, chemotherapy, and radiotherapy. However, GMB rapidly relapses and develops radioresistance. Here, we briefly review the mechanisms underpinning radioresistance and discuss research to stop it and install anti-tumor defenses. Factors that participate in radioresistance are varied and include stem cells, tumor heterogeneity, tumor microenvironment, hypoxia, metabolic reprogramming, the chaperone system, non-coding RNAs, DNA repair, and extracellular vesicles (EVs). We direct our attention toward EVs because they are emerging as promising candidates as diagnostic and prognostication tools and as the basis for developing nanodevices for delivering anti-cancer agents directly into the tumor mass. EVs are relatively easy to obtain and manipulate to endow them with the desired anti-cancer properties and to administer them using minimally invasive procedures. Thus, isolating EVs from a GBM patient, supplying them with the necessary anti-cancer agent and the capability of recognizing a specified tissue-cell target, and reinjecting them into the original donor appears, at this time, as a reachable objective of personalized medicine.

Prospective Evaluation of MGMT-Promoter Methylation Status and Correlations with Outcomes to Temozolomide-Based Chemotherapy in Well-Differentiated Neuroendocrine Tumors

Temozolomide (TEM) as a single agent or in combination with capecitabine (CAPTEM) is active in well-differentiated advanced neuroendocrine tumors (NETs) of gastro-entero-pancreatic and thoracic origin. The predictive role of MGMT-promoter methylation in this setting is controversial. We sought to prospectively evaluate the MGMT-promoter methylation status ability to predict outcomes to TEM-based chemotherapy in patients with NET. A single-center, prospective, observational study has been conducted at the ENETS Center-of-Excellence Outpatient Clinic of the IRCCS Policlinico Sant'Orsola-Malpighi in Bologna, Italy. Patients with advanced, gastro-entero-pancreatic or lung well-differentiated NETs candidate to TEM-based chemotherapy and with available tumor samples for MGMT-promoter methylation assessment were included. The MGMT-promoter methylation status was analyzed by using pyrosequencing. The primary endpoint was progression-free survival (PFS) by the MGMT-promoter methylation status. Secondary endpoints included overall survival (OS), objective response rate (ORR), disease control rate (DCR), and safety. Survival outcomes were compared by restricted mean survival time (RMST) difference. Of 26 screened patients, 22 were finally enrolled in the study. The most frequent NET primary sites were the pancreas (64%) and the lung (23%). MGMT promoter was methylated in five tumors (23%). At a median follow-up time of 47.2 months (95%CI 29.3-89.7), the median PFS was 32.8 months (95%CI 17.2-NA), while the median OS was not reached. Patients in the methylated MGMT group, when compared to those in the unmethylated MGMT group, had longer PFS (median not reached [95%CI NA-NA] vs. 30.2 months [95%CI 15.2-NA], respectively; RMST p = 0.005) and OS (median not reached [95%CI NA-NA] vs. not reached [40.1-NA], respectively; RMST p = 0.019). After adjusting for confounding factors, the MGMT-promoter methylation status was independently associated to the PFS. Numerically higher ORR (60% vs. 24%; p = 0.274) and DCR (100% vs. 88%; p = 1.00) were observed in the methylated vs. unmethylated MGMT group. TEM-based chemotherapy was well-tolerated (adverse events grade ≥3 < 10%). In this prospective study, MGMT-promoter methylation predicted better outcomes to TEM-based chemotherapy in patients with NET.

Chemotherapy in Well Differentiated Neuroendocrine Tumors (NET) G1, G2, and G3: A Narrative Review

Neuroendocrine tumors (NETs) are rare neoplasms with a wide spectrum of clinical behavior, from the long survival of well-differentiated NETs to the dismal prognosis of high-grade neuroendocrine carcinomas (NECs), being G3 NETs a recently recognized intermediate entity. While the role of chemotherapy is well established in NECs, data on NETs mostly derives from small studies, experts' opinions, and extrapolating results from small-cell lung cancer studies. This narrative review aims to summarize available evidence about the use of chemotherapy in the setting of G1-2 NETs and G3 NETs. We performed literature research in PubMed Library for all articles published up to September 2022 about the efficacy of chemotherapy in NETs. Treatment regimens with STZ-5FU, CAPTEM, and anti-metabolite-based treatment are the most active and tolerated in gastroenteropancreatic NETs (GEP-NETs) G1-G2, while platinum-based regimens (FOLFOX/XELOX) and TEM/CAPTEM showed the best activity in thoracic NETs. Solid evidence about chemotherapy efficacy in G3 NETs is still lacking. Literature data support the use of chemotherapy in low-intermediate grade NETs after the failure of other therapies or if tumor shrinkage is needed. Studies assessing G3 NETs independently from NECs are needed to better understand the role of chemotherapy in this setting.

Capecitabine and Temozolomide (CAPTEM) in Advanced Neuroendocrine Neoplasms (NENs): A Systematic Review and Pooled Analysis

Background

Retrospective studies and single center experiences suggest a role of capecitabine combined with temozolomide (CAPTEM) in neuroendocrine tumors (NENs).

Methods

We performed a systematic review to assess the efficacy and safety of CAPTEM in patients affected with NENs, with the aim to better clarify the role of this regimen in the therapeutic algorithm of NENs.

Results

A total of 42 articles and 1818 patients were included in our review. The overall disease control rate was 77% (range 43.5%-100%). The median progression free survival ranged from 4 to 38.5 months, while the median overall survival ranged from 8 to 103 months. Safety analysis showed an occurrence of G3-G4 toxicities in 16.4% of the entire population. The most common toxicities were hematological (27.2%), gastrointestinal (8.3%,) and cutaneous (3.2%).

Conclusion

This systematic review demonstrated that CAPTEM was an effective and relatively safe treatment for patients with advanced well-moderate differentiated NENs of gastroenteropancreatic, lung and unknown origin.

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).

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.

Large Cell Neuroendocrine Carcinoma of the Lung: Current Understanding and Challenges

Large cell neuroendocrine carcinoma of the lung (LCNEC) is a rare and highly aggressive type of lung cancer, with a complex biology that shares similarities with both small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). The prognosis of LCNEC is poor, with a median overall survival of 8-12 months. The diagnosis of LCNEC requires the identification of neuroendocrine morphology and the expression of at least one of the neuroendocrine markers (chromogranin A, synaptophysin or CD56). In the last few years, the introduction of next-generation sequencing allowed the identification of molecular subtypes of LCNEC, with prognostic and potential therapeutic implications: one subtype is similar to SCLC (SCLC-like), while the other is similar to NSCLC (NSCLC-like). Because of LCNEC rarity, most evidence comes from small retrospective studies and treatment strategies that are extrapolated from those adopted in patients with SCLC and NSCLC. Nevertheless, limited but promising data about targeted therapies and immune checkpoint inhibitors in patients with LCNEC are emerging. LCNEC clinical management is still controversial and standardized treatment strategies are currently lacking. The aim of this manuscript is to review clinical and molecular data about LCNEC to better understand the optimal management and the potential prognostic and therapeutic implications of molecular subtypes.

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

Simple Summary

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

Abstract

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

Radiolabeled Somatostatin Analogues for Diagnosis and Treatment of Neuroendocrine Tumors

Simple Summary

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors, presenting in often challenging clinical scenarios, and require multidisciplinary discussion for optimal care. The theranostic approach (DOTA peptides labelled with ⁶⁸Ga for imaging well-differentiated neuroendocrine tumors NETs, and labelled with ⁹⁰Y or ¹⁷⁷Lu for therapy) plays a crucial role in the management of NENs to assess disease extension and criteria for peptide receptor radionuclide therapy (PRRT) eligibility of based on somatostatin receptor (SSTR) expression. The present paper is an overview of currently employed radiolabeled SSTR analogues used for both diagnosis and therapy of NENs. Further emerging radiopharmaceuticals targeting SSTRs (e.g., fluorinated SSTR agonists, radiolabeled SSTR antagonists) as well as strategies to improve PRRT efficacy (by means of implementation of personalized treatment schemes, dosimetry, amelioration of response assessment strategies, and optimization of treatment sequencing) are also discussed. Finally, although very preliminary, some studies employing radiomic features in various kinds of NET are reported.

Abstract

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors that require multidisciplinary discussion for optimal care. The theranostic approach (DOTA peptides labelled with ⁶⁸Ga for diagnosis and with ⁹⁰Y or ¹⁷⁷Lu for therapy) plays a crucial role in the management of NENs to assess disease extension and as a criteria for peptide receptor radionuclide therapy (PRRT) eligibility based on somatostatin receptor (SSTR) expression. On the diagnostic side, [⁶⁸Ga]Ga-DOTA peptides PET/CT (SSTR PET/CT) is the gold standard for imaging well-differentiated SSTR-expressing neuroendocrine tumors (NETs). [¹⁸F]FDG PET/CT is useful in higher grade NENs (NET G2 with Ki-67 > 10% and NET G3; NEC) for more accurate disease characterization and prognostication. Promising emerging radiopharmaceuticals include somatostatin analogues labelled with ¹⁸F (to overcome the limits imposed by ⁶⁸Ga), and SSTR antagonists (for both diagnosis and therapy). On the therapeutic side, the evidence gathered over the past two decades indicates that PRRT is to be considered as an effective and safe treatment option for SSTR-expressing NETs, and is currently included in the therapeutic algorithms of the main scientific societies. The positioning of PRRT in the treatment sequence, as well as treatment personalization (e.g., tailored dosimetry, re-treatment, selection criteria, and combination with other alternative treatment options), is warranted in order to improve its efficacy while reducing toxicity. Although very preliminary (being mostly hampered by lack of methodological standardization, especially regarding feature selection/extraction) and often including small patient cohorts, radiomic studies in NETs are also presented. To date, the implementation of radiomics in clinical practice is still unclear. The purpose of this review is to offer an overview of radiolabeled SSTR analogues for theranostic use in NENs.

Efficacy of Capecitabine and Temozolomide in Small Bowel (Midgut) Neuroendocrine Tumors

Simple Summary

The capecitabine/temozolomide (CAPTEM) regimen has proven activity in pancreatic neuroendocrine tumors (NETs); however, data are limited in NETs of the small bowel. To observe whether this regimen has activity in this patient population, we conducted a retrospective study of all patients with small bowel NETs treated with this regimen at our institution. We found that response rates were poor among patients with low-intermediate grade tumors but higher among patients with high-grade disease. Our findings suggest that the CAPTEM regimen should be reserved for patients with higher-grade small bowel NETs.

Abstract

The capecitabine/temozolomide regimen has significant activity in pancreatic NETs; however, data are limited in NETs of the small bowel (midgut). A retrospective study of all patients with metastatic midgut NETs seen at Moffitt Cancer Center between January 2008 and June 2019 treated with CAPTEM was conducted. 32 patients with proven or suspected well-differentiated primary small bowel NETs (excluding duodenum) were identified. 6 patients were found to have a radiographic response (19%), 5 of whom had high-grade disease. Only one patient among 23 with low/intermediate-grade disease responded (4%), whereas the response rate for patients with high-grade disease was 56%. Among patients with low/intermediate-grade disease, 44% discontinued due to poor tolerability. The CAPTEM regimen appears to have an activity in patients with high-grade small bowel NETs and is largely inactive in patients with low/intermediate-grade tumors.

Perspectives on the diagnostic, predictive and prognostic markers of neuroendocrine neoplasms (Review)

Neuroendocrine neoplasms (NENs) are a heterogeneous group of rare tumors with different types of physiology and prognosis. Therefore, prognostic information, including morphological differentiation, grade, tumor stage and primary location, are invaluable and contribute to the formulation of treatment decisions. Biomarkers that are currently used, including chromogranin A (CgA), serotonin and neuron-specific enolase, are singular parameters that cannot be used to accurately predict variables associated with tumor growth, including proliferation, metabolic rate and metastatic potential. In addition, site-specific biomarkers, such as insulin and gastrin, cannot be applied to all types of NENs. The clinical application of broad-spectrum markers, as it is the case for CgA, remains controversial despite being widely used. Due to limitations of the currently available mono-analyte biomarkers, recent studies were conducted to explore novel parameters for NEN diagnosis, prognosis, therapy stratification and evaluation of treatment response. Identification of prognostic factors for predicting NEN outcome is a critical requirement for the planning of adequate clinical management. Advances in ‘liquid’ biopsies and genomic analysis techniques, including microRNA, circulating tumor DNA or circulating tumor cells and sophisticated biomathematical analysis techniques, such as NETest or molecular image-based biomarkers, are currently under investigation as potentially novel tools for the management of NENs in the future. Despite these recent findings yielding promising observations, further research is necessary. The present review therefore summarizes the existing knowledge and recent advancements in the exploration of biochemical markers for NENs, with focus on gastroenteropancreatic-neuroendocrine tumors.

Chemotherapy in Neuroendocrine Tumors

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.

Treatment patterns and outcomes for patients with newly diagnosed glioblastoma multiforme: a retrospective cohort study

Aim:

Investigate real-world outcomes and healthcare utilization of patients with glioblastoma multiforme (GBM) related to O⁶-methylguanine DNA methyltransferase (MGMT) promoter testing and methylation.

Patients & methods:

US Oncology Network data were analyzed for patients receiving first-line (1L) treatment for GBM.

Results:

Most patients received 1L radiation with temozolomide. Unadjusted median overall survival (OS) was higher in tested versus untested (median:18.1 vs 11.8 months) and in methylated versus unmethylated (median: 25.5 vs 12.4 months). Untested status, unmethylated MGMT and older age were associated with reduced OS and longer 1L treatment with increased OS. Similar findings were observed for progression-free survival. Utilization was similar between cohorts.

Conclusion:

In community oncology practices, MGMT methylation and testing were predictive of better survival in GBM.

We studied the characteristics and survival of patients with newly diagnosed glioblastoma multiforme (GBM) in community-based oncology practices. These patients had received temozolomide and radiotherapy with surgery, which is the standard of care for GBM. We were interested in how patient survival was related to methylation of the O⁶-methylguanine DNA methyltransferase (MGMT) promoter. The study showed that patients with methylated versus unmethylated MGMT GBM survived longer. However, patients who were tested for methylation, whether MGMT was methylated or not, also survived longer. This may be because patients who get tested also get better care in general.

Should temozolomide be used on the basis of O6-methylguanine DNA methyltransferase status in patients with advanced neuroendocrine tumors? A systematic review and meta-analysis

BACKGROUND

Temozolomide (TEM) is an active treatment in metastatic neuroendocrine tumors (NETs). Patients affected by glioblastoma multiforme or advanced melanoma treated with TEM who have deficiency of O⁶-methylguanine DNA methyltransferase (MGMT) have a better responses and survival. However, the predictive role of MGMT in patients with NETs treated with TEM is still debated.

METHODS

We conducted a systematic review of the literature and meta-analysis, based on PRISMA methodology, searching in the main databases (PubMed, Embase, Scopus, Web of Science, Cochrane Library and clinical trial.gov) and the proceedings of the main international congresses, until April 26, 2021.

RESULTS

Twelve out of 616 articles were selected for our analysis, regarding a total of 858 NET patients treated with TEM-based chemotherapy. The status of MGMT had been tested in 513 (60%) patients, using various methods. The pooled overall response rate (ORR) was higher in MGMT-deficient compared with MGMT-proficient NETs, with a risk difference of 0.31 (95% confidence interval, CI: 0.13-0.50; p < 0.001; I²: 73%) and risk ratio of 2.29 (95% CI: 1.34-3.91; p < 0.001; I²: 55%). The pooled progression free survival (PFS) (hazard ratio, HR = 0.56; 95% CI: 0.43-0.74; p < 0.001) and overall survival (OS) (HR = 0.41; 95% CI: 0.20-0.62; p = 0.011) were longer in MGMT-deficient versus MGMT-proficient NETs.

CONCLUSIONS

Our meta-analysis suggested that MGMT status may be predictive of TEM efficacy. However, due to the high heterogeneity of the evaluated studies the risk of biases should be considered. On this hypothesis future homogeneous prospective studies are warranted.

Evaluation of MGMT gene methylation in neuroendocrine neoplasms

Unresectable neuroendocrine neoplasms (NENs) often poorly respond to standard therapeutic approaches. Alkylating agents, in particular temozolomide, commonly used to treat high-grade brain tumors including glioblastomas, have recently been tested in advanced or metastatic NENs, where they showed promising response rates. In glioblastomas, prediction of response to temozolomide is based on the assessment of the methylation status of the MGMT gene, as its product, O-6-methylguanine-DNA methyltransferase, may counteract the damaging effects of the alkylating agent. However, in NENs, such a biomarker has not been validated yet. Thus, we have investigated MGMT methylation in 42 NENs of different grades and from various sites of origin by two different approaches: in contrast to methylation-specific PCR (MSP), which is commonly used in glioblastoma management, amplicon bisulfite sequencing (ABS) is based on high resolution next-generation sequencing and interrogates several additional CpG sites compared to those covered by MSP. Overall, we found MGMT methylation in 74% (31/42) of the NENs investigated. A higher methylation degree was observed in well-differentiated tumors and in tumors originating in the gastrointestinal tract. Comparing MSP and ABS results, we demonstrate that the region analyzed by the MSP test is sufficiently informative of the MGMT methylation status in NENs, suggesting that this predictive parameter could routinely be interrogated also in NENs.

Phase II study of temozolomide monotherapy in patients with extrapulmonary neuroendocrine carcinoma

Extrapulmonary neuroendocrine carcinoma (EPNEC) is a lethal disease with a poor prognosis. Platinum-based chemotherapy is used as the standard first-line treatment for unresectable EPNEC. Several retrospective studies have reported the results of the utilization of temozolomide (TMZ) as a drug for the second-line treatment for EPNEC. Patients with unresectable EPNEC that were resistant to platinum-based combination chemotherapy were recruited for a prospective phase II study of TMZ monotherapy. A 200 mg/m2 dose of TMZ was given from day 1 to day 5, every 4 weeks. Response rate (RR) was evaluated as the primary end-point. The presence of O6 -methylguanine DNA methyltransferase (MGMT) in EPNEC patients was also evaluated as exploratory research. Thirteen patients were enrolled in this study. Primary lesions were pancreas (n = 3), stomach (n = 3), duodenum (n = 1), colon (n = 1), gallbladder (n = 1), liver (n = 1), uterus (n = 1), bladder (n = 1), and primary unknown (n = 1). Each case was defined as pathological poorly differentiated neuroendocrine carcinoma from surgically resected and/or biopsied specimens. The median Ki-67 labeling index was 60% (range, 22%-90%). The RR was 15.4%, progression-free survival was 1.8 months (95% confidence interval [CI], 1.0-2.7), overall survival (OS) was 7.8 months (95% CI, 6.0-9.5), and OS from first-line treatment was 19.2 months (95% CI, 15.1-23.3). No grade 3 or 4 hematological toxicity had occurred and there was one case of grade 3 nausea. One case presented MGMT deficiency and this case showed partial response. Temozolomide monotherapy is a feasible, modestly effective, and safe treatment for patients with unresectable EPNEC following platinum-based chemotherapy, especially those with MGMT deficiency.

Temozolomide alone or in combination with capecitabine in patients with advanced neuroendocrine neoplasms: an Italian multicenter real-world analysis

PURPOSE

Temozolomide (TEM) has been reported to be active alone or in combination with capecitabine (CAP) in patients with neuroendocrine neoplasms (NENs). We retrospectively evaluated activity and toxicity of TEM-based chemotherapy in patients with advanced NENs and explored the potential correlation with clinical/biological factors.

METHODS

Patients received oral TEM alone or in combination with CAP. Objective response rate (ORR) [complete response + partial response (PR)], median progression-free survival (mPFS), and toxicity were calculated. The O⁶-methylguanine-DNA-methyltransferase (MGMT) gene inactivation status in tumor tissue was evaluated by pyrosequencing.

RESULTS

From September 2008 to April 2020, 170 patients (84% progressive on different therapies) were consecutively treated, 114 (67%) patients received TEM-CAP and 56 (33%) TEM alone. Primary tumor sites were: pancreas 98 (58%), gastrointestinal tract 21 (12%), lung 35 (21%), and unknown 16 (9%). The ORR was 28% for the whole population (33% for TEM-CAP and 18% for TEM as single agent). The median OS (mOS) and mPFS of the whole population were 35.6 months (32.6-48.7) and 14.7 months (10.1-18.3), respectively. There were 48% PR in the MGMT hypermethylated, mainly in pancreatic NENs. Vomiting and leukopenia were the most frequent grade 3/4 toxicity.

CONCLUSIONS

This large retrospective analysis suggested that a TEM-based chemotherapy is active in advanced, pretreated NEN patients. It generated solid hypotheses that warrant a future prospective study in a biological homogeneous NEN population and clinical setting.

An Overview on Molecular Characterization of Thymic Tumors: Old and New Targets for Clinical Advances

Thymic tumors are a group of rare mediastinal malignancies that include three different histological subtypes with completely different clinical behavior: the thymic carcinomas, the thymomas, and the rarest thymic neuroendocrine tumors. Nowadays, few therapeutic options are available for relapsed and refractory thymic tumors after a first-line platinum-based chemotherapy. In the last years, the deepening of knowledge on thymus' biological characterization has opened possibilities for new treatment options. Several clinical trials have been conducted, the majority with disappointing results mainly due to inaccurate patient selection, but recently some encouraging results have been presented. In this review, we summarize the molecular alterations observed in thymic tumors, underlying the great biological differences among the different histology, and the promising targeted therapies for the future.

Association between MGMT status and response to alkylating agents in patients with neuroendocrine neoplasms: a systematic review and meta-analysis

Background: O⁶-methylguanine-DNA methyltransferase (MGMT) is a specific DNA damage reversal repair protein. The influence of MGMT status on alkylating agent sensitivity in patients with neuroendocrine neoplasms (NENs) is controversial. We conducted a meta-analysis to assess the influence of MGMT status on the therapeutic sensitivity of alkylating agents in patients with NENs.

Methods: We searched PubMed, EmBase, and Cochrane library public databases through 3 July 2019. The objective response rate (ORR) was the outcome data of interest. Subgroup analysis was performed according based on MGMT methylation and expression of MGMT protein.

Results: Eleven studies were included in the meta-analysis. The proportion of patients with NENs that achieved an ORR after alkylating agent treatment was higher in the MGMT-deficient group than the non-deficient group (OR: 5.00; 95% CI: 3.04–8.22; P < 0.001; I²: 3%). Similar results were noted in the MGMT methylation and MGMT protein expression subgroups.

Conclusion: Patients with NENs and MGMT methylation or low protein expression had a higher ORR proportion than patients without MGMT methylation or high protein expression. The MGMT status can be used as a biological indicator of the response to alkylating agent treatment in patients with NENs.

A Ki-67 Index to Predict Treatment Response to the Capecitabine/Temozolomide Regimen in Neuroendocrine Neoplasms: A Retrospective Multicenter Study

OBJECTIVE

The efficacy of the capecitabine/temozolomide (CAPTEM) regimen has been demonstrated in metastatic neuroendocrine neoplasms (NENs), but because of varying response rates among the patients, biomarkers to predict its response are greatly needed. Here, we investigated the clinical utility of a Ki-67 index to predict the CAPTEM regimen objective responses and select patients who could benefit from this regimen.

METHODS

Metastatic NENs patients treated with the CAPTEM regimen from 4 high-volume medical centers were selected and grouped in a training and validation cohort. The classification and regression tree (CART) was generated to identify the optimal threshold of Ki-67 for stratifying the patients into different Ki-67 range groups based on their response to the CAPTEM regimen.

RESULTS AND CONCLUSIONS

The overall response rate (ORR) and disease control rate of the entire cohort (N = 151) were 26.5 and 76.2%, respectively, with a median progression-free survival (PFS) of 12.0 months. CART analysis showed that patients in the Ki-67 range group 10-40% demonstrated a significantly higher ORR than those in Ki-67 >40 and <10% groups (p < 0.001 in the training cohort and p = 0.036 in the validation cohort). Response to the CAPTEM regimen was not influenced by the expression of O6-methylguanine-DNA methyltransferase or primary tumor location. Multivariate analysis identified the Ki-67 index as the only independent prognostic factor for overall survival (p = 0.031) and PFS (p = 0.006). The proposed Ki-67 index was externally validated and could be used to clinically identify suitable metastatic NENs patients who could achieve an optimal cytoreduction using the CAPTEM regimen.

Recent Advances in the Management of Typical and Atypical Lung Carcinoids

Neuroendocrine neoplasms of the lung represent about 20% to 30% of all neuroendocrine tumors. On the basis of clinical and pathologic characteristics, 2 different categories of tumors may be defined: poorly differentiated neuroendocrine neoplasms, characterized by a high rate of recurrences and poor prognosis, and well-differentiated neuroendocrine neoplasms (typical carcinoids and atypical carcinoids), which generally display an indolent course. Lung carcinoids represent only 1% to 5% of all lung malignancies, but their incidence has significantly increased over the past 30 years. Surgery is the reference standard of treatment for lung carcinoids with locoregional disease. For advanced or unresectable lung carcinoids, several therapeutic options are available, but the choice should be shared within a multidisciplinary team to ensure optimal therapeutic outcomes. We describe the current management of these rare neoplasms.

O6-methylguanine DNA methyltransferase and glucose transporter 2 in foregut and hindgut gastrointestinal neuroendocrine neoplasms

Background

Streptozocin (STZ) is used for treating both pancreatic (PanNET) and gastrointestinal (GI-NET) neuroendocrine tumors but its therapeutic efficacy is relatively low in GI-NETs. Therefore, it has become pivotal to select GI-NET patients who could benefit from STZ treatment. STZ is transported via the glucose transporter 2 (GLUT2) into the cells and the loss of O6-methylguanine DNA methyltransferase (MGMT) also increases its therapeutic efficacy. Therefore, GLUT2 high and MGMT low status could be the surrogate markers of STZ.

Methods

In this study, we examined the MGMT and GLUT2 status in gastrointestinal neuroendocrine neoplasm (NEN). We studied 84 NEN cases: 33 foregut and 37 hindgut GI-NETs and 14 gastrointestinal neuroendocrine carcinomas (GI-NECs).

Results

In GI-NETs, MGMT scores of ≥2 and ≥ 3 were 77% (54/70) and 56% (39/70), respectively, and GLUT2 scores of ≥4 and ≥ 6 were 30% (21/70) and 4.3% (3/70), respectively. Methylation-specific polymerase chain reaction revealed that MGMT promoter methylation was detected only in 2/14 GI-NECs but none of the included GI-NETs. GLUT2 (GLUT2 score) and MGMT immunoreactivity (MGMT and H-scores) were both significantly correlated with Ki-67 labeling index (GLUT2 score: P = 0.0045, ρ = − 0.4570; MGMT score: P = 0.0064, ρ = − 0.4399; H-score: P = 0.0110, ρ = − 0.4135) and MGMT immunoreactivity were significantly correlated with GLUT2 immunoreactivity (MGMT score: P = 0.0198; H-score, P = 0.0004, ρ = 0.5483) in hindgut NETs, but not in foregut NETs. However, discrepancies from the above correlation between GLUT2 and MGMT immunoreactivity were detected in several GI-NET cases which could be potential candidates for STZ therapy.

Conclusion

The evaluation of MGMT and GLUT2 status could provide an important information in planning STZ therapy in GI-NET patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07579-6.

Molecular profile of pancreatic neuroendocrine neoplasms (PanNENs): Opportunities for personalized therapies

Pancreatic neuroendocrine neoplasms (panNENs) are the second most common epithelial tumors of the pancreas. Despite improvements in prognostic grading and staging systems, it remains a challenge to predict the clinical behavior of panNENs and the response to specific therapies given the high degree of heterogeneity of these tumors. Most panNENs are nonfunctional and present as advanced disease. However, systemic therapies provide modest benefits. Therefore, there is a need for predictive biomarkers to develop personalized treatment and to advance new drug development. The somatostatin receptors remain the only clinically established prognostic and predictive biomarkers in panNENs. Oncogenic drivers are at a very low frequency. Commonly mutated genes in panNENs include MEN1, chromatin remodeling genes (DAXX and ATRX), and mammalian target of rapamycin pathway genes. In contrast, poorly differentiated neuroendocrine carcinomas (panNECs), which carry a very poor prognosis, have distinctive mutations in certain genes (eg, RB1 and p53). Ongoing research to integrate epigenomics will provide tremendous opportunities to improve current understanding of the clinical heterogeneity of pancreatic neuroendocrine tumors and provide invaluable insight into the biology of these tumors, new drug development, and establishing personalized therapies.

Phase I trial of TRC102 (methoxyamine HCl) in combination with temozolomide in patients with relapsed solid tumors and lymphomas

BACKGROUND

TRC102 inhibits base excision repair by binding abasic sites and preventing AP endonuclease processing; it potentiates the activity of alkylating agents, including temozolomide, in murine models. In published xenograft studies, TRC102 enhanced the antitumor effect of temozolomide regardless of cell line genetic characteristics, e.g., O6-methylguanine DNA methyltransferase (MGMT), mismatch repair (MMR), or p53 status.

MATERIALS AND METHODS

We conducted a phase 1 trial of TRC102 with temozolomide given orally on days 1-5 of 28-day cycles in adult patients with refractory solid tumors that had progressed on standard therapy. Tumor induction of nuclear biomarkers of DNA damage response (DDR) γH2AX, pNBs1, and Rad51 was assessed in the context of MGMT and MMR protein expression for expansion cohort patients.

RESULTS

Fifty-two patients were enrolled (37 escalation, 15 expansion) with 51 evaluable for response. The recommended phase 2 dose was 125 mg TRC102, 150 mg/m2 temozolomide QDx5. Common adverse events (grade 3/4) included anemia (19%), lymphopenia (12%), and neutropenia (10%). Four patients achieved partial responses (1 non-small cell lung cancer, 2 granulosa cell ovarian cancer, and 1 colon cancer) and 13 patients had a best response of stable disease. Retrospective analysis of 15 expansion cohort patients did not demonstrate a correlation between low tumor MGMT expression and patient response, but treatment induced nuclear Rad51 responses in 6 of 12 patients.

CONCLUSIONS

The combination of TRC 102 with temozolomide is active, with 4 of 51 patients experiencing a partial response and 13 of 51 experiencing stable disease, and the side effect profile is manageable.

Therapeutic options in lung neuroendocrine tumors: between established concepts and new hopes

Typical (TC) and atypical (AC) carcinoids are low-grade neuroendocrine tumors (NETs) of the lung and, are neglected diseases in respect of both high-grade NETs of the lung (i.e. small-cell lung cancer and large-cell neuroendocrine carcinoma) and gastroenteropancreatic (GEP)-NETs. AC and TC account for 2 and 0.2% of all thoracic malignancies, respectively, and have a 12.9% chance of metastatic spread at diagnosis, reaching up to 20% during disease history. There are very few trials specifically designed for lung NETs, and therapeutic options are mainly derived by studies carried out in patients with GEP-NETs. We report a case of a patient affected by AC progressed to available standard treatments who received off-label treatment with sunitinib, a well-known multitarget tyrosine-kinase inhibitor with marked antiangiogenic activity, used routinely for the treatment of GEP-NETs. During treatment, the patient required the administration of an alternative schedule to improve tolerability, with benefit, and achieved a partial response according to the RECIST criteria, which is unusual in NETs. We critically reviewed available data supporting the use of somatostatin analogs, chemotherapy, and target therapies (everolimus and sunitinib) in advanced lung NETs. In the review, ongoing trials in lung NETs and future developments in this research field are also discussed.

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

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

Post first-line dacarbazine or temozolomide in neuroendocrine carcinoma

OBJECTIVE

First-line chemotherapy in metastatic neuroendocrine carcinomas (NECs) is based on etoposide and platinum. However, there is no standard concerning second-line treatment. The objective of this study was to evaluate efficacy and tolerance of dacarbazine or temozolomide in metastatic digestive NEC as post first-line treatment.

MATERIAL AND METHODS

This study included patients with a metastatic NEC of digestive or unknown primary site. All patients received platinum-etoposide as first-line chemotherapy. Primary endpoint was progression-free survival (PFS). Secondary endpoints were clinical/morphological responses, toxicity, and overall survival (OS).

RESULTS

Twenty-seven patients were included: 17 received dacarbazine and 10 temozolomide as post-first line treatments. Median PFS was 3.0 (95%CI (2.2;3.7)) months. There was no significant difference between dacarbazine and temozolomide on PFS. Clinical and morphological responses were found in 12 and 9 patients, respectively. Median OS was 7.2 (95%CI (2.2;12.2)) months. The toxicity profile was that expected with such treatments.

CONCLUSION

LV5FU2-dacarbazine or temozolomide-capecitabine chemotherapies allow a temporary clinical response for almost half of patients and/or a morphological response for a third of patients.

The functioning side of the pancreas: a review on insulinomas

PURPOSE

Insulinomas are a rare type of neuroendocrine tumors, originating in the pancreas, difficult to diagnose and to treat. Due to its rarity, insulinomas are a not well-known pathological entity; thus, the diagnostic process is frequently a medical challenge with many possible differential diagnoses. The diagnostic process varies between non-invasive procedures, such as the fasting test or imaging techniques, and invasive ones. Insulinomas are rarely malignant, but the glycemic imbalance correlated with this tumor can frequently alter the quality of life of the patients and the consequent hypoglycemia can be extremely dangerous. Moreover, insulinomas can be associated with different genetic syndromes, such as Multiple Endocrine Neoplasia 1, accompanied by other specific symptoms. There are many different treatment strategies, depending on the need to control symptoms or control diseases progression, the only curative one being surgery.

METHODS AND RESULTS

We reviewed the evidences present in the literature on insulinomas and reported its main clinical characteristics and management strategies.

CONCLUSION

The aim of this review of the literature is to present the current knowledge on insulinomas, exploring the main clinical characteristics, the diagnostic tools, and the therapeutic strategies.

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

The traditionally promulgated perspectives of neuroendocrine neoplasms (NEN) as rare, indolent tumours are blunt and have been outdated for the last 2 decades. Clear increments in their incidence over the past decades render them increasingly clinically relevant, and at initial diagnosis many present with nodal and/or distant metastases (notably hepatic). The molecular pathogenesis of these tumours is increasingly yet incompletely understood. Those arising from the small bowel (SB) or pancreas typically occur sporadically; the latter may occur within the context of hereditary tumour predisposition syndromes. NENs can also be associated with endocrinopathy of hormonal hypersecretion. Tangible advances in the development of novel biomarkers, functional imaging modalities and therapy are especially applicable to this sub-set of tumours. The management of SB and pancreatic neuroendocrine tumours (NET) may be challenging, and often comprises a multidisciplinary approach wherein surgical, medical, interventional radiological and radiotherapeutic modalities are implemented. This review provides a comprehensive overview of the epidemiology, pathophysiology, diagnosis and treatment of SB and pancreatic NETs. Moreover, we provide an outlook of the future in these tumour types which will include the development of precision oncology frameworks for individualised therapy, multi-analyte predictive biomarkers, artificial intelligence-derived clinical decision support tools and elucidation of the role of the microbiome in NEN development and clinical behaviour.

Multiple Assays to Determine Methylguanine-Methyltransferase Status in Lung Carcinoids and Correlation with Clinical and Pathological Features

BACKGROUND

O6-methylguanine-methyltransferase (MGMT) is a key enzyme for the DNA repair machinery strongly associated with response to alkylating agents in different tumors. Data on its expression and related clinical impact in neuroendocrine tumors are limited to the gastro-entero-pancreatic system, with controversial results in terms of prognostic or predictive value. In lung carcinoids, although clinical efficacy of alkylating agents has been shown in small studies, very few data to date are available on MGMT status.

OBJECTIVE

To assess MGMT status in lung carcinoids using multiple assays and to compare data with major clinical and pathological features.

METHODS

A retrospective series of 95 lung carcinoids and 51 control cases of high-grade neuroendocrine lung carcinomas was analyzed for MGMT promoter methylation, MGMT gene expression, and MGMT protein expression using pyrosequencing, quantitative real-time PCR, and immunohistochemistry, respectively.

RESULTS

MGMT protein expression was inversely correlated with MGMT promoter methylation and positively with MGMT gene expression. MGMT promoter methylation progressively increased from carcinoids to high-grade carcinomas. In the carcinoid group, decreased MGMT gene expression was significantly associated with aggressive features (atypical histotype, grade G2, larger tumor size, higher T stage, and positive nodal status) but not with survival. MGMT promoter methylation was associated with lower stage and negative nodal status.

CONCLUSIONS

Our study investigated MGMT status in a large series of lung carcinoids in the attempt to move forward a rational use of alkylating agents in these tumors. Interestingly, low MGMT gene expression defines a subgroup of lung carcinoids with aggressive features.

Capecitabine and Temozolomide in Patients with Advanced Pulmonary Carcinoid Tumours

BACKGROUND

Temozolomide and capecitabine (CAPTEM) chemotherapy is known to be active in patients with pancreatic neuroendocrine tumours.

OBJECTIVE

This retrospective analysis set out to describe the efficacy and toxicity of CAPTEM in patients with advanced pulmonary carcinoids (PCs).

METHODS

Patients were included with advanced PC who had been treated with a maximum of 6 cycles of oral temozolomide 200 mg/m2 on days 10-14 and capecitabine 750 mg/m2 b.i.d. on days 1-14, repeated every 28 days, -followed by monthly intramuscular injection of octreotide 30 mg long-acting release as maintenance treatment.

RESULTS

Of the 33 patients, all with well-differentiated PC, 61% had atypical carcinoid, 36% had Ki-67 index >10% and 42% had ≥3 organs involved by metastasis. CAPTEM was administered as first-line treatment in 42% of patients, and 17% had received prior somatostatin analogue treatment. Six patients (18%) achieved a partial response, 19 (58%) had stable disease and 8 (24%) developed progressive disease. After a median time of follow-up of 34.8 months, median progression-free survival (PFS) was 9.0 months and median overall survival 30.4 months. Median duration of disease response was 21.7 months and median duration of disease control 9.7 months. Patients with multi-organ metastasis had shorter PFS, but only when treated as second or third line with CAPTEM (p = 0.023).

CONCLUSIONS

CAPTEM induced a modest response and PFS rate, comparable to other studies with temozolomide in patients with advanced PC. The efficacy of CAPTEM should be compared to that of monotherapy with temozolomide in a prospective clinical trial.

Clinical Epigenetics of Neuroendocrine Tumors: The Road Ahead

Neuroendocrine tumors, or NETs, are cancer originating in neuroendocrine cells. They are mostly found in the gastrointestinal tract or lungs. Functional NETs are characterized by signs and symptoms caused by the oversecretion of hormones and other substances, but most NETs are non-functioning and diagnosis in advanced stages is common. Thus, novel diagnostic and therapeutic strategies are warranted. Epigenetics may contribute to refining the diagnosis, as well as to identify targeted therapy interfering with epigenetic-sensitive pathways. The goal of this review was to discuss the recent advancement in the epigenetic characterization of NETs highlighting their role in clinical findings.

MGMT Promoter Methylation and Parathyroid Carcinoma

Context

Parathyroid carcinoma (PC) is extremely rare. Prognosis is poor, with no known evidence-based systemic therapies. We previously reported complete remission in a patient with metastasized parathyroid carcinoma and high tumor MGMT promoter methylation status who was treated with temozolomide.

Objective

To study MGMT promoter methylation status in an additional set of aggressive parathyroid tumors.

Design/Setting

The study included 12 patients: 7 with sporadic and 5 with familial primary hyperparathyroidism (two of the latter carried a CDC73 gross deletion). Patient 9 is the previously described patient with PC and high MGMT methylation status. Her daughter (patient 12) had surgery for severe primary hyperparathyroidism due to atypical parathyroid adenoma during pregnancy. Eleven patients thus had PC and one had atypical parathyroid adenoma. MGMT promoter methylation status was determined from DNA extracted from primary (n = 10) or metastatic (n = 2) tumors. A mean methylation level >20% was considered high. Patient 11 had metastatic PC and received temozolomide cycles.

Results

Only the previously published patient (patient 9) had high tumor MGMT promoter methylation status. This was not a characteristic of the atypical parathyroid adenoma of the daughter (patient 12). Patient 11 (CDC73 intragenic deletion) has disseminated PC, low MGMT promoter methylation, and stable disease on follow-up after temozolomide treatment.

Conclusion

High MGMT promoter methylation status seems rare in PC. However, as demonstrated in other neuroendocrine tumors, some patients with disseminated PC might benefit from temozolomide. Demonstration of high methylation status could be a predictor of positive response to temozolomide treatment.

Clinical applications of (epi)genetics in gastroenteropancreatic neuroendocrine neoplasms: Moving towards liquid biopsies

High-throughput analysis, including next-generation sequencing and microarrays, have strongly improved our understanding of cancer biology. However, genomic data on rare cancer types, such as neuroendocrine neoplasms, has been lagging behind. Neuroendocrine neoplasms (NENs) develop from endocrine cells spread throughout the body and are highly heterogeneous in biological behavior. In this challenging disease, there is an urgent need for new therapies and new diagnostic, prognostic, follow-up and predictive biomarkers to aid patient management. The last decade, molecular data on neuroendocrine neoplasms of the gastrointestinal tract and pancreas, termed gastroenteropancreatic NENs (GEP-NENs), has strongly expanded. The aim of this review is to give an overview of the recent advances on (epi)genetic level and highlight their clinical applications to address the current needs in GEP-NENs. We illustrate how molecular alterations can be and are being used as therapeutic targets, how mutations in DAXX/ATRX and copy number variations could be used as prognostic biomarkers, how far we are in identifying predictive biomarkers and how genetics can contribute to GEP-NEN classification. Finally, we discuss recent studies on liquid biopsies in the field of GEP-NENs and illustrate how liquid biopsies can play a role in patient management. In conclusion, molecular studies have suggested multiple potential biomarkers, but further validation is ongoing.

Temozolomide Alone or Combined with Capecitabine for the Treatment of Advanced Pancreatic Neuroendocrine Tumor

BACKGROUND

The combination of capecitabine (CAP) with temozolomide (TEM) chemotherapy in advanced pancreatic neuroendocrine tumors (PanNET) relies on limited evidence. We compared TEM-CAP to TEM alone in patients with advanced PanNET.

METHODS

Consecutive patients with advanced PanNET treated with TEM or TEM-CAP between 2004 and 2017 in three expert centers were included. Progression-free survival (PFS), tolerance, tumor response, and overall survival were compared between the two groups. Propensity-based analyses were performed to reduce confounding bias due to the nonrandomized setting.

RESULTS

TEM and TEM-CAP were administered to 38 patients and 100 patients, respectively, with a median age of 58 years. The patients in the TEM group more often had hormonal syndromes (p = 0.03), a longer median delay to diagnosis (p = 0.001), and a higher number of pretreatment lines (p < 0.001). The performance status was 0 in 58% versus 65% of the patients, and tumor's median Ki-67 index was 8% versus 11%, respectively. Tolerance was similar, except that there were more cases of asthenia in the TEM group (p = 0.017) and more cases of hand-foot syndrome in the TEM-CAP group (p = 0.025). The objective response rate was 34% versus 51% (p = 0.088). The raw median PFS was similar with TEM and with TEM-CAP (21.4 vs. 19.8 months, p = 0.84). Although CAP tended to decrease the risk of progression in Cox multivariate analysis (HR 0.65, p = 0.12), it had no effect after adjustment for the propensity score (HR 1.06, p = 0.80).

CONCLUSIONS

TEM-CAP might not prolong PFS but might achieve a higher response rate than TEM alone. Hence, TEM-CAP might be preferred when tumor shrinkage is the main therapeutic objective. Otherwise, TEM might be adequate for patients with an impaired performance status or in case of extrahepatic metastases.

Lung and digestive neuroendocrine neoplasms. From WHO classification to biomarker screening: Which perspectives?

The recent classifications of lung and digestive neuroendocrine neoplasms (NENs) make a fundamental distinction between well- and poorly-differentiated neoplasms. Well-differentiated NENs are termed carcinoids in the lung and neuroendocrine tumors in the gastroenteropancreatic sphere; their risk of malignancy is highly variable; histological grading is used to stratify patients into prognostically significant groups. Poorly-differentiated NENs are termed neuroendocrine carcinoma in both the lung and the digestive sphere; they constantly are of high grade of malignancy; two types are recognized on the basis of tumor cell morphology, the small cell and the large cell types. Recent studies have largely uncovered the genetic landscape of several subsets of well-differentiated NENs (lung, pancreas, small intestine) and of poorly-differentiated NENs. Some molecular markers may help to the differential diagnosis between highly proliferative neuroendocrine tumors and neuroendocrine carcinomas, especially in the pancreas. In well-differentiated tumors, MGMT status is proposed as a predictive marker of the response to temozolomide, but remains to be validated. In poorly-differentiated neoplasms, large cell neuroendocrine carcinoma has been shown to be a heterogeneous category, with some cases presenting the same molecular signature than small cell carcinoma and others the same signature than adenocarcinomas of the same body site. Rb protein has been recently shown to be a potential marker of response to platinum salts in neuroendocrine carcinoma. Much remains to be done to translate the rapid progress in the molecular understanding of NENS into diagnostic, prognostic or predictive markers.

O6-methylguanine-DNA methyltransferase (MGMT) status in neuroendocrine tumors: a randomized phase II study (MGMT-NET)

INTRODUCTION

Neuroendocrine tumors (NETs) are rare, but their incidence is rising. Alkylating agents (ALKY), temozolomide and streptozotocin, are the main chemotherapies used for advanced pancreatic NETs. According to retrospective data, O6-methylguanine-DNA methyltransferase (MGMT) status appears to be a predictive factor of the response to ALKY.

AIMS

The main objective is to evaluate the value of tumor MGMT promoter (pMGMT) methylation in the prediction of the objective response (OR) at 3 months in patients treated with ALKY. Secondly, we will evaluate the value of MGMT immunohistochemistry and the efficacy of treatment with ALKY vs. oxaliplatin-based chemotherapy (Ox).

MATERIALS AND METHODS

A national, prospective, open-label, randomized, controlled and multicenter trial was designed. Main inclusion criteria are: adult patients with well-differentiated advanced duodeno-pancreatic, lung, or unknown primitive NETs with a validated indication for chemotherapy. pMGMT methylation will be assessed by pyrosequencing, but an ancillary study will compare this technique with others ones including MGMT immunohistochemistry.

RESULTS

A total of 104 patients will be randomly assigned (1:1 for unmethylated or 2:1 for methylated pMGMT NETs) to either the ALKY arm or to the Ox arm.

CONCLUSION

Recruitment started on October 16, 2018 (NCT03217097) and will be open in 21 centers in France.

Aggressive and Malignant Prolactinomas

Prolactin-secreting tumors (prolactinomas) represent the most common pituitary tumor type, accounting for 47-66% of functional pituitary tumors. Prolactinomas are usually benign and controllable tumors as they express abundant levels of dopamine type 2 receptor (D2), and can be treated with dopaminergic drugs, effectively reducing prolactin levels and tumor volume. However, a proportion of prolactinomas exhibit aggressive features (including invasiveness, relevant growth despite adequate dopamine agonist treatment, and recurrence potential) and few may exhibit metastasizing potential (carcinomas). In this context, the clinical, pathological, and molecular definitions of malignant and aggressive prolactinomas remain to be clearly defined, as primary prolactin-secreting carcinomas are similar to aggressive adenomas until the presence of metastases is detected. Indeed, standard molecular and histological analyses do not reflect differences between carcinomas and adenomas at a first glance and have limitations in prediction of the aggressive progression of prolactinomas, wherein the causes underlying the aggressive behavior remain unknown. Herein we present a comprehensive, multidisciplinary review of the most relevant epidemiological, clinical, pathological, genetic, biochemical, and molecular aspects of aggressive and malignant prolactinomas.