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

Combined Lanreotide Autogel and Temozolomide Treatment of Progressive Pancreatic and Intestinal Neuroendocrine Tumors: The Phase II SONNET Study

BACKGROUND

In advanced neuroendocrine tumors (NET), antiproliferative treatment options beyond somatostatin analogs remain limited. Temozolomide (TMZ) has shown efficacy in NET alone or combined with other drugs.

MATERIALS AND METHODS

SONNET (NCT02231762) was an open, multicenter, prospective, phase II study to evaluate lanreotide autogel 120 mg (LAN) plus TMZ in patients with progressive advanced/metastatic grade 1/2 gastroenteropancreatic (GEP) NET or of unknown primary. Patients could be enrolled at first-line or higher therapy line. The primary endpoint was disease control rate ([DCR], rate of stable disease [SD], partial [PR], and complete response [CR]) at 6 months of LAN and TMZ. Patients with nonfunctioning (NF) NET without progression at 6 months were randomized to 6-month LAN maintenance or watch and wait, patients with functioning (F)-NET with clinical benefit (PR, SD) continued on LAN.

RESULTS

Fifty-seven patients were recruited. The majority of patients received the study drug at second or higher treatment line and had an NET G2. DCR at 6 months LAN and TMZ was 73.5%. After 6 months of further LAN maintenance, 54.5% of patients with F-NET and 71.4% with NF-NET had SD or PR vs 41.7% with NF-NET on observation only. LAN and TMZ were effective in all subgroups analyzed. At 12 months of follow-up, median progression-free survival was 11.1 months. Median serum chromogranin A decreased except in NF-NET on observation. O6-methylguanine DNA methyltransferase promoter methylation appeared to better reflect TMZ response than loss of gene expression. During combination therapy, the most frequent treatment-emergent adverse events grade 3/4 reported were nausea (14%), thrombocytopenia (12.3%), and neutropenia (8.8%). Four deaths were reported resulting from severe adverse events not considered related to study medication.

CONCLUSIONS

LAN plus TMZ is a treatment option for patients with progressive GEP-NET with more aggressive biological profile showing a manageable safety profile.

Current and emerging strategies for the management of advanced/metastatic lung neuroendocrine tumors

Pulmonary neuroendocrine tumors represent a spectrum of disease ranging from typical carcinoid tumors to small cell lung cancers. The incidence of low-grade pulmonary NETs has been increasing, leading to improved awareness and the need for more treatment options for this rare cancer. Somatostatin analogs continue to be the backbone of therapy and may be followed or accompanied by targeted therapy, chemotherapy, and immune therapy. The recent addition of peptide receptor radionuclide therapy (PRRT) to the treatment armamentarium of NETs has led to the development of targeted alpha therapy to overcome PRRT resistance and minimize off-target adverse effects. Herein, we aim to highlight current treatment options for patients with advanced low grade pulmonary NETs along with emerging therapies, sequencing of therapies, upcoming clinical trials, and the importance of a multidisciplinary team to improve patient outcomes.

Approach to the Patient: Insulinoma

Insulinomas are hormone-producing pancreatic neuroendocrine neoplasms with an estimated incidence of 1 to 4 cases per million per year. Extrapancreatic insulinomas are extremely rare. Most insulinomas present with the Whipple triad: (1) symptoms, signs, or both consistent with hypoglycemia; (2) a low plasma glucose measured at the time of the symptoms and signs; and (3) relief of symptoms and signs when the glucose is raised to normal. Nonmetastatic insulinomas are nowadays referred to as "indolent" and metastatic insulinomas as "aggressive." The 5-year survival of patients with an indolent insulinoma has been reported to be 94% to 100%; for patients with an aggressive insulinoma, this amounts to 24% to 67%. Five percent to 10% of insulinomas are associated with the multiple endocrine neoplasia type 1 syndrome. Localization of the insulinoma and exclusion or confirmation of metastatic disease by computed tomography is followed by endoscopic ultrasound or magnetic resonance imaging for indolent, localized insulinomas. Glucagon-like peptide 1 receptor positron emission tomography/computed tomography or positron emission tomography/magnetic resonance imaging is a highly sensitive localization technique for seemingly occult, indolent, localized insulinomas. Supportive measures and somatostatin receptor ligands can be used for to control hypoglycemia. For single solitary insulinomas, curative surgical excision remains the treatment of choice. In aggressive malignant cases, debulking procedures, somatostatin receptor ligands, peptide receptor radionuclide therapy, everolimus, sunitinib, and cytotoxic chemotherapy can be valuable options.

European Neuroendocrine Tumour Society (ENETS) 2023 guidance paper for nonfunctioning pancreatic neuroendocrine tumours

This ENETS guidance paper for well-differentiated nonfunctioning pancreatic neuroendocrine tumours (NF-Pan-NET) has been developed by a multidisciplinary working group, and provides up-to-date and practical advice on the management of these tumours. Using the extensive experience of centres treating patients with NF-Pan-NEN, the authors of this guidance paper discuss 10 troublesome questions in everyday clinical practice. Our many years of experience in this field are still being verified in the light of the results of new clinical, which set new ways of proceeding in NEN. The treatment of NF-Pan-NEN still requires a decision of a multidisciplinary team of specialists in the field of neuroendocrine neoplasms.

Epidemiology of Neuroendocrine Neoplasms and Results of Their Treatment with [177Lu]Lu-DOTA-TATE or [177Lu]Lu-DOTA-TATE and [90Y]Y-DOTA-TATE-A Six-Year Experience in High-Reference Polish Neuroendocrine Neoplasm Center

Neuroendocrine neoplasms (NENs) are a group of neoplasms arising from neuroendocrine cells. The worldwide incidence and prevalence of the NENs are estimated to be 6/100,000 and 35/100,000, respectively. Those numbers are increasing every decade, requiring higher and higher diagnosis and treatment costs. Radioligand therapy (RLT) using beta-emitting radioisotopes is an efficient and relatively safe method of treatment, typically used as a second-line treatment. RLT tolerability is higher than other available pharmacotherapies (chemotherapy or tyrosine kinase inhibitors). Recent studies show an increase in overall survival among patients treated with RLT. The present study aimed to learn the epidemiology of NENs in Poland and assess the effectiveness of RLT in a high-reference center. A prospective analysis of 167 patients treated with RLT in one of Poland's highest-reference NEN centers was performed. The analysis covered 66 months of observation (1 December 2017-30 May 2023), during which 479 RLT single administrations of radioisotope were given. The standard procedure was to give four courses of [177Lu]Lu-DOTA-TATE alone, or tandem therapy-[177Lu]Lu-DOTA-TATE and [90Y]Y-DOTA-TATE. Grading analysis showed that most patients had non-functioning G2 NEN with a mean Ki-67 of 6.05% (SD ± 6.41). The most common primary tumor location was the pancreas. Over two-thirds of patients did undergo surgery due to primary tumors or distant metastases. The majority of patients were using lanreotide as a chronically injected somatostatin analog. Median progression-free survival (PFS) on somatostatin analogs was 21.0 (IQR = 29.0) months. Directly after the last course of RLT, disease stabilization was noted in 69.46% of patients, partial regression was noted in 20.36% of patients, complete regression was noted in 0.60% of patients, and progression was noted in 9.58% of patients. In long-term follow-up, the median observation time among patients who underwent four treatment cycles (n = 108) was 29.8 (IQR = 23.9) months. Stabilization of the disease was observed in 55.56% of the patients and progression was observed in 26.85% of the patients, while 17.59% of patients died. Median PFS was 29.3 (IQR 23.9), and the median OS was 34.0 months (IQR 16.0). The mean age of NEN diagnosis is the sixth decade of life. It takes almost three years from NEN diagnosis to the start of RLT. In long-term observation, RLT leads to disease stabilization in over half of the patients with progressive disease. No differences in PFS or OS depend on the radioisotope used for RLT. In Poland, organized coordination of NEN treatment in high-reference centers ensures the continuity of patient care.

Novel treatment strategy of targeting epigenetic dysregulation in pancreatic neuroendocrine tumors

BACKGROUND

Epigenetic dysregulation is an integral step in the progression of pancreatic neuroendocrine tumors. We hypothesized that tumor suppressor repression by DNA methyltransferase 1 in pancreatic neuroendocrine tumors could be targeted with epigenetic treatment.

METHODS

Resected pancreatic neuroendocrine tumors from 32 patients were stained for DNA methyltransferase 1 and scored. Human (BON1) and murine (STC) pancreatic neuroendocrine tumor cells were treated with DNA methyltransferase 1 inhibitor 5-azacytidine and chemotherapeutic agents 5-fluorouracil and temozolomide. Cell proliferation assay and tumor suppressor gene analysis were performed with qRT-PCR and Clarion S microarray. Tumor measurements were compared in a murine treatment model.

RESULTS

High DNA methyltransferase scores were associated with high Ki-67 (6.7% vs 70.6% P < .01), mitotic rate (0.0% vs 31.3%), and grade (20.0% vs 80.4%, P < .01). Treatment with 5-azacytidine and chemotherapy resulted in a reduction of cell proliferation compared to chemotherapy alone in BON1 (77.3% vs 53.1%, P < .001) and STC (73.4% vs 34.2%, P < .001). Treatment with 5-azacytidine and chemotherapy resulted in upregulation of tumor suppressors CDKN1A (7.6 rel. fold, P < .001), BRCA2 (4.3 rel. fold, P < .001), and CDH1 (6.0 rel. fold, P = .026) in BON1 and CDKN1a (14.5 rel. fold, P < .001) and CDH (17.5 rel. fold, P < .001) in STC. In microarray, 5-azacytidine drove global genetic changes in combination treatment. In vivo tumors treated with chemotherapy measured 88.6 ± 19.54 mm³ vs 52.89 ± 10.51 mm³ in those treated with combination therapy (P = .009).

CONCLUSION

Epigenetic dysregulation with DNA methyltransferase 1 is associated with pancreatic neuroendocrine tumors and is a potential targetable strategy. 5-azacytidine and chemotherapy in combination can reduce cell proliferation, upregulate silenced tumor suppressor genes, and decrease in vivo tumors in pancreatic neuroendocrine tumors.

Systemic Therapy for Pancreatic Neuroendocrine Tumors

Patients with metastatic or advanced pancreatic neuroendocrine tumors (NETs) carry poorer prognoses relative to patients with other NETs due to bulkier and often, more proliferative baseline disease. Patients with these tumors also possess more approved treatment options relative to patients with other NETs, making therapeutic sequencing nuanced. As such, defining optimal therapeutic sequencing and developing more potent cytoreductive treatments for patients are significant areas of research need in the field. Herein this review, we discuss the current systemic therapy landscape, our approach to therapeutic sequencing in the clinic and ongoing studies seeking to define optimal sequencing of systemic therapies, and novel therapeutics in development, for patients with pancreatic NETs. We limit the scope of this latter topic to agents with preclinical or clinical rationale over the last 8 years to provide a contemporary view of the drug development landscape and focus primarily on new types of peptide receptor radionuclide therapy, anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors and anti-vascular endothelial growth receptor tyrosine kinase inhibitor plus immunotherapy combinations.

Preoperative Chemoradiotherapy With Capecitabine With or Without Temozolomide in Patients With Locally Advanced Rectal Cancer: A Prospective, Randomised Phase II Study Stratified by O6-Methylguanine DNA Methyltransferase Status: KCSG-CO17-02

AIMS

To evaluate the clinical efficacy of adding temozolomide (TMZ) to preoperative capecitabine (CAP)-based chemoradiotherapy in patients with locally advanced rectal cancer (LARC) and validate O⁶-methylguanine DNA methyltransferase (MGMT) methylation status as a predictive marker for TMZ combined regimens.

MATERIALS AND METHODS

LARC patients with clinical stage II (cT3-4N0) or III (cT_anyN+) disease were enrolled. They were stratified into unmethylated MGMT (uMGMT) and methylated MGMT (mMGMT) groups by methylation-specific polymerase chain reaction before randomisation and were then randomly assigned (1:1) to one of four treatment arms: uMGMT/CAP (arm A), uMGMT/TMZ + CAP (arm B), mMGMT/CAP (arm C) and mMGMT/TMZ + CAP (arm D). The primary end point was the pathological complete response (pCR) rate.

RESULTS

Between November 2017 and July 2020, 64 patients were randomised. Slow accrual caused early study termination. After excluding four ineligible patients, 60 were included in the full analysis set. The pCR rate was 15.0% (9/60), 0%, 14.3%, 18.8% and 26.7% for the entire cohort, arms A, B, C and D, respectively (P = 0.0498 between arms A and D). The pCR rate was 9.7% in the CAP group (arms A + C), 20.7% in the TMZ + CAP group (arms B + D), 6.9% in the uMGMT group (arms A + B) and 22.6% in the mMGMT group (arms C + D). Grade 1-2 nausea or vomiting was significantly more frequent in the TMZ + CAP treatment groups (arms B + D) than in the CAP treatment groups (arms A + C, P < 0.001) with no difference in grade 3 adverse events. There were no grade 4 or 5 adverse events.

CONCLUSION

The addition of TMZ to CAP-based chemoradiotherapy tended to improve pCR rates, particularly in those with mMGMT LARC. MGMT status may warrant further investigation as a predictive biomarker for chemotherapeutic agents and radiotherapy.

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.

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.

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.

Temozolomide in aggressive pituitary tumours and pituitary carcinomas

Survival for patients with aggressive pituitary tumours (APT) and pituitary carcinomas (PC) has significantly improved following the increasing use of temozolomide (TMZ) since the first reports of response in 2006. TMZ was established as first line chemotherapy for APT/PC in the 2018 ESE guidelines on the management of APT/PC. There is no controversy over its use as salvage therapy however there is increasing interest in exploring TMZ use earlier in the treatment algorithm for APT/PC. Overall response rates as reported in systematic reviews are around 40% but stable disease in another 25% illustrates the clinical effectiveness of TMZ. Response is higher among functional compared to non-functional tumours. Where maximal radiation thresholds have not been reached in a patient, combination radiotherapy and TMZ appears more effective. Whether combination TMZ and capecitabine (CAPTEM) offers increased benefit remains uncertain particularly given added toxicity. O6-methyl guanine DNA methyl transferase (MGMT) status is important in determining response to treatment, although examination via immunohistochemistry versus PCR-based promoter-methylation analysis remains somewhat controversial. Optimal duration of TMZ treatment has still not been determined although longer treatment courses have been associated with increased progression-free survival. Treatment options following disease progression after TMZ remain unclear but include a second course of TMZ, immunotherapy and targeted oncological agents such as bevacizumab and lapatinib as well as peptide receptor radionuclide treatment (PRRT). An experienced pituitary multidisciplinary team is essential to all management decisions in patients with APT/PC.

Capecitabine and temozolomide for metastatic intermediate to high-grade pancreatic neuroendocrine neoplasm: a single center experience

BACKGROUND/AIMS

The combination of capecitabine and temozolomide (CAPTEM) is one of the treatment options for metastatic pancreatic neuroendocrine neoplasms (pNENs). This study aims to evaluate the efficacy of CAPTEM in patients with metastatic intermediate to high-grade pancreatic neuroendocrine tumor (pNET) or carcinoma (pNEC).

METHODS

This study was conducted retrospectively in a single center. Patients were treated for intermediate to high-grade tumor with 750 mg/m² of capecitabine twice daily from day 1 to 14 and 200 mg/m² of temozolomide once daily from day 10 to 14, repeating twice in a cycle of 28 days. The primary outcomes were durations of overall survival (OS) and progression-free survival (PFS). The secondary outcomes consisted of objective response rate and disease control rate.

RESULTS

A total of 12 patients (grade 2 NET in six, grade 3 NET in three, NEC in three patients) who received CAPTEM were included in this study. Patients received a median of five cycles (range, 2 to 46) of CAPTEM. The median dose combined 1,150 mg of capecitabine and 300 mg of temozolomide. The median OS and PFS were 41.2 months (range, 3.2 to 167) and 39.7 months (range, 2.1 to 100), respectively. Patients with NET had longer OS and PFS compared to those of patients with NEC (p = 0.002 and p = 0.028). High Ki-67 proliferative index (&gt; 50%) was significantly associated with poor survival outcomes.

CONCLUSION

CAPTEM showed favorable survival outcomes in patients with metastatic intermediate to high-grade pNENs. Our study supports that CAPTEM may be an effective treatment option for metastatic pNENs.

Prognostic and Predictive Biomarkers for Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PanNETs) represent a clinically challenging disease because these tumors vary in clinical presentation, natural history, and prognosis. Novel prognostic biomarkers are needed to improve patient stratification and treatment options. Several putative prognostic and/or predictive biomarkers (eg, alternative lengthening of telomeres, alpha-thalassemia/mental retardation, X-linked (ATRX)/Death Domain Associated Protein (DAXX) loss) have been independently validated. Additionally, recent transcriptomic and epigenetic studies focusing on endocrine differentiation have identified PanNET subtypes that display similarities to either α-cells or β-cells and differ in clinical outcomes. Thus, future prospective studies that incorporate genomic and epigenetic biomarkers are warranted and have translational potential for individualized therapeutic and surveillance strategies.

Capecitabine and temozolomide (CAPTEM) is effective in metastatic well-differentiated gastrointestinal neuroendocrine tumors

OBJECTIVE

The aim of this study was to investigate the outcomes and prognostic factors of patients with metastatic gastrointestinal neuroendocrine tumor (mGI-NET) who were treated with capecitabine and temozolomide (CAPTEM) and somatostatin receptor ligand (octreotide or lanreotide).

METHODS

Clinicopathological characteristics and treatment outcomes of 43 patients with mGI-NET were retrospectively evaluated. Overall survival (OS) and progression-free survival (PFS) were evaluated using Kaplan-Meier curve. Cox-regression analysis was used to assess prognostic variables.

RESULTS

There were 23 (53.5%) men and 20 women (46.5%) with a median age of 59 years (range 27-85 y). Patients were given octreotide (86.0%) or lanreotide (14.0%) with CAPTEM. In patients with well-differentiated mGI-NET, median PFS was 17.4 months, and the disease control rate was 71.1%. Patients with poorly differentiated mGI-NET showed no response, and the median PFS was 4.5 months. Four (9.3%) discontinued the medication due to toxicity. Anemia (37.2%), thrombocytopenia (25.6%), and fatigue (16.3%) were the most prevalent adverse events. The 5-year OS rate was 61.0% in all patients during a median follow-up of 33.8 months. In multivariate analysis, age (P = 0.014) and tumor differentiation (P < 0.001) were statistically significant factors for OS.

CONCLUSIONS

CAPTEM plus somatostatin receptor ligands were efficacious and well tolerated in individuals with well-differentiated mGI-NET. However, it was ineffective for those with poorly differentiated tumors. Age of 60 years or elder and poorly differentiated tumors were related to a poor patient prognosis.

The optimal duration of capecitabine plus temozolomide in patients with well-differentiated pancreatic NETs with or without maintenance therapy

BACKGROUND

The optimal duration of capecitabine combined with temozolomide (CapTem) for metastatic pancreatic neuroendocrine tumours (PanNETs) remains controversial. The present study aimed to assess the activity and safety of prolonged CapTem and Cap maintenance therapy in patients with metastatic PanNETs.

METHODS

Retrospective real-world data of 94 patients with metastatic PanNETs were obtained from one cancer centre. Fifteen patients were treated with Cap maintenance therapy after fixed 12-13 cycles of CapTem (group I), 44 patients were treated with prolonged CapTem until disease progression (group II), and 35 patients were treated with fixed 12-13 cycles of CapTem (group III).

RESULTS

The mean ± SE follow-up period was 41.79 ± 26.31 months. The median CapTem treatment duration was 12 months in group I and 14 months in group II. The median time to best partial response was 12 months both in groups I and group II. The objective response rates of groups I and II were significantly higher than those of group III (73.3%, 41.9%, and 20%, respectively, p = .002). The median progression-free survival (mPFS) of group I and group II was significantly higher than that of group III (35 months, 26 months vs. 19 months, p < .001). Safety analysis of the three groups indicated rare events of grade 3-4 toxicities, with nausea, vomiting, fatigue, and anaemia being the most common adverse effects.

CONCLUSIONS

Patients with PanNETs who responded well to CapTem treatment may benefit from prolonged CapTem and Cap maintenance therapy after fixed cycles. Prospective studies are encouraged to further explore the prolonged CapTem treatment and maintenance therapy.

Pharmacotherapeutic Management of Well-Differentiated Neuroendocrine Tumors in Older Patients: Current Status and Potential Therapies

Neuroendocrine tumors are a rare and heterogenous group of neoplasms that arise from hormone-producing cells throughout the body, with the greatest increase in incidence occurring among older adults aged ≥ 65 years. Despite this, there is currently a lack of data regarding the safety and efficacy of systemic treatment for older adults with neuroendocrine tumors. In this review, we provide a synopsis of the current standard-of-care pharmacotherapeutic treatments for neuroendocrine tumors, with an emphasis on available data in older adults. The benefits of various systemic options such as somatostatin analogs, tryptophan hydroxylase inhibition, molecular targeted agents, peptide receptor radionuclide therapy, and chemotherapy were similar between older adults compared to younger patients. However, real-world data regarding tolerance in the older adult population with neuroendocrine tumors are needed. Future development of novel systemic therapies in the neuroendocrine tumor treatment landscape and their inclusion of and potential impact on older adults living with neuroendocrine tumors is warranted.

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.

Single-cell RNA sequencing reveals spatiotemporal heterogeneity and malignant progression in pancreatic neuroendocrine tumor

Aims: Using Single-cell RNA sequencing (scRNA-seq), we explored the spatiotemporal heterogeneity of pancreatic neuroendocrine tumors (pNETs) and the underlying mechanism for malignant progression.

Methods: scRNA-seq was conducted on three tumor tissues (two primary tissues from different sites, one liver metastatic lesion), one normal liver tissue, and peripheral blood mononuclear cells from one patient with a metastatic G2 pNET, followed by bioinformatics analysis and validation in a pNETs cohort.

Results: The transcriptome data of 24.544 cells were obtained. We identified subpopulations of functional heterogeneity within malignant cells, immune cells, and fibroblasts. There were intra- and inter-heterogeneities of cell subpopulations for malignant cells, macrophages, T cells, and fibroblasts among all tumor sites. Cell trajectory analysis revealed several hallmarks of carcinogenesis, including the hypoxia pathway, metabolism reprogramming, and aggressive proliferation, which were activated at different stages of tumor progression. Evolutionary analysis based on mitochondrial mutations defined two dominant clones with metastatic capacity. Finally, we developed a gene signature (PCSK1 and SMOC1) defining the metastatic potential of the tumor and its prognostic value was validated in a cohort of thirty G1/G2 patients underwent surgical resection.

Conclusions: Our scRNA-seq analysis revealed intra- and intertumor heterogeneities in cell populations, transcriptional states, and intercellular communications among primary and metastatic lesions of pNETs. The single-cell level characterization of the spatiotemporal dynamics of malignant cell progression provided new insights into the search for potential novel prognostic biomarkers of pNETs.

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 of advanced gastroenteropancreatic neuroendocrine neoplasia, are we on the way to personalised medicine?

Gastroenteropancreatic neuroendocrine neoplasia (GEPNEN) comprises clinically as well as prognostically diverse tumour entities often diagnosed at late stage. Current classification provides a uniform terminology and a Ki67-based grading system, thereby facilitating management. Advances in the study of genomic and epigenetic landscapes have amplified knowledge of tumour biology and enhanced identification of prognostic and potentially predictive treatment subgroups. Translation of this genomic and mechanistic biology into advanced GEPNEN management is limited. 'Targeted' treatments such as somatostatin analogues, peptide receptor radiotherapy, tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors are treatment options but predictive tools are lacking. The inability to identify clonal heterogeneity and define critical oncoregulatory pathways prior to therapy, restrict therapeutic efficacy as does the inability to monitor disease status in real time. Chemotherapy in the poor prognosis NEN G3 group, though associated with acceptable response rates, only leads to short-term tumour control and their molecular biology requires delineation to provide new and more specific treatment options.The future requires an exploration of the NEN tumour genome, its microenvironment and an identification of critical oncologic checkpoints for precise drug targeting. In the advance to personalised medical treatment of patients with GEPNEN, clinical trials need to be based on mechanistic and multidimensional characterisation of each tumour in order to identify the therapeutic agent effective for the individual tumour.This review surveys advances in NEN research and delineates the current status of translation with a view to laying the basis for a genome-based personalised medicine management of advanced GEPNEN.

Current treatments and future potential of surufatinib in neuroendocrine tumors (NETs)

Neuroendocrine tumors (NETs) are rare, heterogeneous, often indolent tumors that predominantly originate in the lungs and gastrointestinal tract. An understanding of the biology and tumor microenvironment of NETs has led to the development of molecularly targeted treatment options including somatostatin analogs, tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors and peptide receptor radionuclide therapy. Although increases in progression-free survival have been demonstrated, most currently approved NET therapies are limited by the development of tumor resistance. Surufatinib (HMPL-012, previously known as sulfatinib) is a new, oral, small-molecule tyrosine kinase inhibitor that potently inhibits vascular endothelial growth-factor receptor 1-3, fibroblast growth-factor receptor 1, and colony-stimulating-factor-1 receptor. This unique combination of molecular activities inhibits tumor angiogenesis, regulates tumor-immune evasion, and may decrease tumor resistance. Surufatinib demonstrated statistically significant, clinically meaningful antitumor activity, including tumor shrinkage, in two phase III studies recently completed in China in advanced pancreatic NETs and advanced extrapancreatic NETs. The safety profile of surufatinib in neuroendocrine tumors studies was consistent with previous surufatinib clinical studies. In an ongoing study in United States (US) patients with NETs of pancreatic origin and NETs of extrapancreatic origin previously treated with everolimus or sunitinib, surufatinib has also demonstrated promising efficacy. Furthermore, the pharmacokinetic and safety profile of surufatinib in US patients is similar to data collected in studies done in China. These positive phase III results support the efficacy of surufatinib in patients with advanced, progressive, well-differentiated NETs regardless of tumor origin.

Sequential Capecitabine/Temozolomide and Sunitinib Treatment in Patients With Metastatic Well-Differentiated Grade 1/Grade 2 Pancreatic Neuroendocrine Tumors

OBJECTIVE

The role of alternate sequential administration of sunitinib and capecitabine/temozolomide (CAPTEM) in metastatic pancreatic neuroendocrine tumors (PanNETs) remains unexplored. We thus aimed to analyze the efficacy and tolerability of this strategy in advanced grade 1/grade 2 PanNETs.

METHODS

In total, data of 43 patients with metastatic PanNET were collected from a real-world database of a cancer center. Twenty-four patients were treated with sunitinib followed by CAPTEM (group 1), and 19 patients were treated with CAPTEM followed by sunitinib (group 2).

RESULTS

Twenty-three patients were treated with first-line sunitinib or CAPTEM, and 20 patients were pretreated with somatostatin analog (SSA) or SSA in combination with transcatheter arterial chemoembolization. The objective response rate with first-line treatment was similar in both groups, whereas that with second-line treatment was higher in group 1 than in group 2, albeit with no significant differences (21.1% vs 5.3%, respectively; P = .205). Median progression-free survival (mPFS) for first-line and second-line treatments did not differ between the 2 groups (11 and 12 months vs 12 and 8 months, respectively). Following subgroup analyses, treatment with first-line sunitinib and sunitinib after pretreated SSA had a longer mPFS than that with second-line sunitinib after CAPTEM (11 months vs 8 months, respectively; P = .046), whereas treatment with first-line CAPTEM and CAPTEM after pretreated SSA had an mPFS similar to that of second-line CAPTEM after sunitinib treatment. CAPTEM and sunitinib had similar tolerability.

CONCLUSION

Alternating sunitinib and CAPTEM were well tolerated and associated with similar mPFS in grade 1/grade 2 PanNETs. However, larger prospective studies are required to investigate the efficacy of alternate sequential therapies for metastatic PanNET.

Nordic guidelines 2021 for diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms

BACKGROUND

The diagnostic work-up and treatment of patients with gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN) has undergone major advances and new methods are introduced. Furthermore, an update of the WHO classification has resulted in a new nomenclature for GEP-NEN that is implemented in the clinic.

AIM

These Nordic guidelines summarise the Nordic Neuroendocrine Tumour Group's current view on how to diagnose and treat GEP-NEN patients and aims to be useful in the daily practice for clinicians.

Capecitabine plus temozolomide in patients with grade 3 unresectable or metastatic gastroenteropancreatic neuroendocrine neoplasms with Ki-67 index <55%: single-arm phase II study

BACKGROUND

Grade 3 neuroendocrine neoplasms (NENs) of gastroenteropancreatic (GEP) origin with Ki-67 indices <55% do not respond well to platinum-based chemotherapy. The combination of capecitabine and temozolomide (CAPTEM) has shown favorable responses in grade 1-2 NENs, but has rarely been studied in patients with grade 3 NENs.

PATIENTS AND METHODS

This open-label, single-arm phase II trial included patients with unresectable or metastatic grade 3 NENs of GEP origin with Ki-67 indices <55% enrolled between June 2017 and July 2020. Patients received oral capecitabine 750 mg/m2 twice daily on days 1 to 14 and oral temozolomide 200 mg/m2 once daily on days 10 to 14 every 4 weeks. Histologic findings were centrally reviewed after the completion of enrollment. The primary endpoint was overall response rate, and the secondary endpoints were progression-free survival (PFS), overall survival (OS), and adverse events.

RESULTS

Of the 30 patients included in the full analysis set, 1 (3.3%) achieved complete response, 8 (26.7%) had partial responses, and 14 (46.7%) had stable disease, making the overall response rate 30.0%. At a median follow-up of 19.2 months, the median PFS was 5.9 months and the median OS was not reached. Patients with well-differentiated NENs showed significantly better median PFS (9.3 months versus 3.5 months, P = 0.005) and median OS (not reached versus 6.2 months, P = 0.004) than patients with poorly differentiated tumors. Expression of O6-methyl-guanine methyltransferase protein did not correlate with clinical outcomes. The most common grade 3-4 adverse events were thrombocytopenia (10%), anemia (6.7%), and nausea (6.7%).

CONCLUSIONS

CAPTEM was effective and well tolerated in patients with grade 3 GEP-NENs with Ki-67 indices <55%, with superior efficacy outcomes compared with the historical controls receiving platinum-based chemotherapy.

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.

Digestive Well-Differentiated Grade 3 Neuroendocrine Tumors: Current Management and Future Directions

Digestive well-differentiated grade 3 neuroendocrine tumors (NET G-3) have been clearly defined since the 2017 World Health Organization classification. They are still a rare category lacking specific data and standardized management. Their distinction from other types of neuroendocrine neoplasms (NEN) not only lies in morphology but also in genotype, aggressiveness, functional imaging uptake, and treatment response. Most of the available data comes from pancreatic series, which is the most frequent tumor site for this entity. In the non-metastatic setting, surgical resection is recommended, irrespective of grade and tumor site. For metastatic NET G-3, chemotherapy is the main first-line treatment with temozolomide-based regimen showing more efficacy than platinum-based regimen, especially when Ki-67 index <55%. Targeted therapies, such as sunitinib and everolimus, have also shown some positive therapeutic efficacy in small samples of patients. Functional imaging plays a key role for detection but also treatment selection. In the second or further-line setting, peptide receptor radionuclide therapy has shown promising response rates in high-grade NEN. Finally, immunotherapy is currently investigated as a new therapeutic approach with trials still ongoing. More data will come with future work now focusing on this specific subgroup. The aim of this review is to summarize the current data on digestive NET G-3 and explore future directions for their management.

Metastatic Pheochromocytomas and Abdominal Paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are believed to harbor malignant potential; about 10% to 15% of pheochromocytomas and up to 50% of abdominal paragangliomas will exhibit metastatic behavior.

EVIDENCE ACQUISITION

Extensive searches in the PubMed database with various combinations of the key words pheochromocytoma, paraganglioma, metastatic, malignant, diagnosis, pathology, genetic, and treatment were the basis for the present review.

DATA SYNTHESIS

To pinpoint metastatic potential in PPGLs is difficult, but nevertheless crucial for the individual patient to receive tailor-made follow-up and adjuvant treatment following primary surgery. A combination of histological workup and molecular predictive markers can possibly aid the clinicians in this aspect. Most patients with PPGLs have localized disease and may be cured by surgery. Plasma metanephrines are the main biochemical tests. Genetic testing is important, both for counseling and prognostic estimation. Apart from computed tomography and magnetic resonance imaging, molecular imaging using 68Ga-DOTATOC/DOTATATE should be performed. 123I-MIBG scintigraphy may be performed to determine whether 131I-MIBG therapy is a possible option. As first-line treatment in patients with metastatic disease, 177Lu-DOTATATE or 131I-MIBG is recommended, depending on which shows best expression. In patients with very low proliferative activity, watch-and-wait or primary treatment with long-acting somatostatin analogues may be considered. As second-line treatment, or first-line in patients with high proliferative rate, chemotherapy with temozolomide or cyclophosphamide + vincristine + dacarbazine is the therapy of choice. Other therapies, including sunitinib, cabozantinib, everolimus, and PD-1/PDL-1 inhibitors, have shown modest effect.

CONCLUSIONS

Metastatic PPGLs need individualized management and should always be discussed in specialized and interdisciplinary tumor boards. Further studies and newer treatment modalities are urgently needed.

Multicenter Analysis of Treatment Outcomes for Systemic Therapy in Well Differentiated Grade 3 Neuroendocrine Tumors (NET G3)

Well-differentiated grade 3 neuroendocrine tumors (NET G3) have been distinguished from poorly differentiated neuroendocrine carcinomas (NEC) in the most current WHO classifications. Commonly applied first-line chemotherapy protocols with cisplatin or carboplatin in combination with etoposide (PE) are less effective in NET G3 than NEC. Suggested alternative treatment protocols have not been studied in first-line therapy of NET G3 so far. We performed a retrospective analysis of patients with NET G3 in the databases of 3 German cancer centers. Out of 142 patients, 136 patients received palliative first-line therapy: overall response rate (ORR) was 35.1% for PE (n = 37), 56.4% for FOLFOX (n = 39), 27.3% for temozolomide/capecitabine (TEM/CAP) (n = 22), 45.0% for streptozotocin/5-fluorouracil (STZ/5-FU) (n = 20), and 16.7% for other (n = 18). Median progression-free survival (PFS) for PE was 6.9 months. Compared to PE, PFS in the other treatment groups was 6.9 months for FOLFOX (p = 0.333), 12.0 months for TEM/CAP (p = 0.093), 4.8 months for STZ/5-FU (p = 0.919), and 14.1 months for other (p = 0.014). In a univariate setting, all non-PE patients combined showed a significantly prolonged PFS vs. PE (9.0 months; p = 0.049) which could not be confirmed in a multivariate analysis. In conclusion, NET G3 with FOLFOX showed the highest ORR, and with TEM/CAP showed the longest PFS. Further prospective evaluation of the optimal therapeutic strategy for this tumor entity is needed.

An updated analysis of the epidemiologic trends of neuroendocrine tumors in Taiwan

The incidence of neuroendocrine tumors (NETs) has been increasing in recent decades. Previously, we reported the incidence and survival of NETs in Taiwan by analyzing the 1996–2008 data from the Taiwan Cancer Registry. Here we performed an updated analysis on the incidence and survival of NETs in Taiwan from 1996 to 2015. The incidence of NETs was 0.244 per 100,000 in 1996 and increased to 3.162 per 100,000 in 2015. The most common site of NETs was rectum (29.65%), followed by lung/bronchus (17.22%), and pancreas (10.71%). The 5- and 10-year overall survival rates of all NETs were 54.6% and 45.3%, respectively. Female and younger NETs patients had a better survival. The survival of all NETs diagnosed between 2010 and 2015 was better than those diagnosed between 2004 and 2009. Among the common sites of NETs, an improved survival of pancreatic NETs diagnosed between 2010 and 2015 compared to those diagnosed between 2004 and 2009 was observed. Overall, the incidence of NETs in Taiwan has continued to increase. The survival of pancreatic NET has shown a recent improvement. The development of novel therapeutic agents has the potential to improve the prognosis of NETs of other sites in the near future.

The clinical characteristics and survival associations of pancreatic neuroendocrine tumors: does age matter?

Background

Pancreatic neuroendocrine tumor (pNET) is the second most common epithelial neoplasm of the pancreas. As in pancreatic adenocarcinoma (PDAC), patients with different onset ages display different clinical features and prognosis. We grouped pNET patients into the early-onset pNET (EOpNET) and typical age-at-onset pNET (TOpNET) to investigate the effect of onset age on their clinical characteristics and prognosis.

Methods

Data were collected retrospectively from the Surveillance, Epidemiology, and End Results (SEER) database (2004-2015; cohort 1) and the Fudan University Shanghai Cancer Center (FUSCC) (2005-2018; cohort 2). The clinical characteristics were compared using chi-squared tests. Cox proportional hazards regression was used to evaluate hazard ratios (HRs) and 95% confidence intervals (CIs), and overall survival was formulated by Kaplan-Meier curves.

Results

In total, data from 5,368 and 330 patients were included from the SEER database and the FUSCC, respectively. Gender did not affect survival in the EOpNET group. Tumors located in the tail (HR: 0.721, 95% CI: 0.63-0.83, P<0.001) and body (HR: 0.712, 95% CI: 0.60-0.85, P=0.001) had a lower risk of death compared to tumors in the head of the pancreas in the TOpNET group. The overall survival of the EOpNET group {136 [3-143] months} was better than the TOpNET group {85 [3-143] months} (P<0.001) in the SEER database. Results from the FUSCC group were similar to the SEER cohort.

Conclusions

The EOpNET group had significantly better overall survival than the TOpNET group, and early surgical resection is encouraged for all pNET patients. In any future personalized treatment of pNET, the patient's onset age should be considered as an important factor in guiding treatment and prognosis.

Benign-Appearing Glucagonoma Undergoing Malignant Transformation after a Prolonged Period

Glucagonoma are rare neuroendocrine tumors arising in the Langerhans islets of the pancreas. We report a patient with glucagonoma differentiation into a malignant form after 13 years. A 63-year-old asymptomatic man was evaluated for an enhancing lesion at the distal pancreas. Physical examination was normal. Laboratory values were normal except for an elevated serum glucagon level (206 pg/mL, Ref. 50-150). Somatostatin and other tumor markers were normal. A PET scan confirmed abnormal uptake at the distal pancreas, correlating with a CT scan. The patient underwent laparoscopic distal pancreatectomy with resection of a 2.6-cm mass which predominantly expressed glucagon. Serum glucagon levels normalized immediately postoperatively. He remained asymptomatic for 13 years with normal blood glucose, glucagon, and chromogranin levels and normal surveillance MRI scans. Thirteen years following surgery, an elevated serum glucagon level (230 pg/mL) was observed. At this time he also remained asymptomatic. Abdominal MRI and a PET scan revealed hepatic lesions. Biopsy of the hepatic lesion confirmed metastatic glucagonoma. The patient was treated with lanreotide, which normalized the serum glucagon levels, and the tumor size remained stable for 12 months of follow-up. Complete remission without any treatment for more than 13 years confirmed the benign course of the glucagon-secreting tumor. The precipitating factors are unknown. This case highlights the importance of continuous monitoring of neuroendocrine tumors even beyond 10 years.

Pancreatic neuroendocrine tumors: Therapeutic challenges and research limitations

Pancreatic neuroendocrine tumors (PNETs) are known to be the second most common epithelial malignancy of the pancreas. PNETs can be listed among the slowest growing as well as the fastest growing human cancers. The prevalence of PNETs is deceptively low; however, its incidence has significantly increased over the past decades. According to the American Cancer Society’s estimate, about 4032 (> 7% of all pancreatic malignancies) individuals will be diagnosed with PNETs in 2020. PNETs often cause severe morbidity due to excessive secretion of hormones (such as serotonin) and/or overall tumor mass. Patients can live for many years (except for those patients with poorly differentiated G3 neuroendocrine tumors); thus, the prevalence of the tumors that is the number of patients actually dealing with the disease at any given time is fairly high because the survival is much longer than pancreatic ductal adenocarcinoma. Due to significant heterogeneity, the management of PNETs is very complex and remains an unmet clinical challenge. In terms of research studies, modest improvements have been made over the past decades in the identification of potential oncogenic drivers in order to enhance the quality of life and increase survival for this growing population of patients. Unfortunately, the majority of systematic therapies approved for the management of advanced stage PNETs lack objective response or at most result in modest benefits in survival. In this review, we aim to discuss the broad challenges associated with the management and the study of PNETs.

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.

Medical Treatment of Advanced Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (panNENs) are relatively rare but their incidence has increased almost sevenfold over the last four decades. Neuroendocrine neoplasms are classified according to their histologic differentiation and their grade. Their grade is based on their Ki-67 proliferation index and mitotic index. Their prognosis is highly variable according to these elements and treatments also vary according to their classification. Surgery is the only curative treatment for localized and advanced panNENs and offers a better prognosis than non-surgical treatments. In the case of an advanced panNEN without the possibility of resection and/or ablation, medical treatment remains the cornerstone for improving survival and preserving quality-of-life. PanNENs are considered as chemosensitive tumors, unlike midgut neuroendocrine tumors. Thus, panNENs can be treated with chemotherapy, but targeted therapies and somatostatin analogs are also treatment options. The scarcity and heterogeneity of NENs make their management difficult. The present review aims to clarify the medical treatments currently available for advanced panNENs, based on their characteristics, and to propose a treatment algorithm.

Digestive Neuroendocrine Neoplasms (NEN): French Intergroup clinical practice guidelines for diagnosis, treatment and follow-up (SNFGE, GTE, RENATEN, TENPATH, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SFR)

INTRODUCTION

This document is a summary of the French Intergroup guidelines regarding the management of digestive neuroendocrine neoplasms (NEN) published in February 2020 (www.tncd.org).

METHODS

All French medical societies involved in the management of NEN took part in this work. Recommendations were graded into four categories (A, B, C or D), according to the level of evidence found in the literature until May 2019.

RESULTS

The management of NEN is challenging because of their heterogeneity and the increasing complexity of diagnostic and therapeutic procedures. Pathological analysis is required for their diagnostic and prognostic characterization, which mainly relies on differentiation, grade and stage. The two main emergency situations are functioning syndromes and poorly-differentiated carcinoma. Chromogranin A is the main biochemical marker of NET, although of limited clinical interest. Initial characterization relies on morphological and isotopic imaging. The treatment of localized NET relies on watchful follow-up and local or surgical resection depending on its supposed aggressiveness. Treatment options for metastatic disease include surgery, somatostatin analogues, chemotherapy, targeted therapies, organ-driven locoregional therapies and peptide-receptor radionuclide therapy. As specific predictive factors of treatment efficacy are yet to be identified and head-to-head comparisons have not or only rarely been performed, the therapeutic strategy currently depends on prognostic factors. Cumulative toxicity and the impact of treatment on quality of life must be considered since survival is relatively long in most patients with NET.

CONCLUSION

These guidelines are proposed to achieve the most beneficial therapeutic strategy in clinical practice as the therapeutic landscape of NEN is becoming ever more complex. These recommendations are permanently being reviewed.

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.

Temozolomide Is a Potential Therapeutic Tool for Patients With Metastatic Pheochromocytoma/Paraganglioma-Case Report and Review of the Literature

Context: Metastatic pheochromocytoma/paraganglioma (MPP) therapy mainly involves radionuclide therapy, chemotherapy, and targeted therapy. In recent years, temozolomide (TMZ) showed great promise in some MMP patients, especially those with SDHB germline mutation. We reported a patient with MPP who did not have any known germline genetic change and responded remarkably well to TMZ monotherapy. Case presentation: The patient was a 41-year-old woman with local and distant recurrence (soft tissues and bone metastases) of retroperitoneal paraganglioma. She suffered from dizziness, palpitation, sweating, weight loss and constipation, with the blood pressure fluctuating substantially from 130/100 mmHg to 190/120 mmHg, although she was on phenoxybenzamine and metoprolol medication. The patient showed clinical and radiological response after 3-cycle TMZ therapy. Upon 15 cycles of TMZ therapy, her symptoms were dramatically alleviated, urinary norepinephrine excretion decreased from 1,840 μg/24 h to 206 μg/24 h, and CT showed that the lesions further shrank. Molecular profiling of the tumor tissue of the patient revealed hypermethylation of the O6-methylguanine-DNA-methyltransferase (MGMT) promoter and a negative immunostaining for MGMT. Globally, only 26 cases of MPP treated with TMZ have been described so far. TMZ is effective, especially in patients with SDHB mutation, which can be explained by the silencing of MGMT expression as a consequence of MGMT promoter hypermethylation in SDHB-mutated tumors. Although, in general, patients with SDHB mutation or MGMT promoter hypermethylation have better response to TMZ, there are also exceptions. Severe side effects are uncommon, with only 17.4% patients experiencing Grade 3 toxicities, including lymphopenia, and hypertension. Conclusions: TMZ is effective and safe in MPP patients, and, it may work better on patients with SDHB-related MPP. Measurement of MGMT expression might help assess the tumor sensitivity to TMZ but this needs further systematic investigation.

Targeting Angiogenesis in Pancreatic Neuroendocrine Tumors: Resistance Mechanisms

Despite being infrequent tumors, the incidence and prevalence of pancreatic neuroendocrine tumors (P-NETs) has been rising over the past few decades. In recent years, rigorous phase III clinical trials have been conducted, allowing the approval of several drugs that have become the standard of care in these patients. Although various treatments are used in clinical practice, including somatostatin analogues (SSAs), biological therapies like sunitinib or everolimus, peptide receptor radionuclide therapy (PRRT) or even chemotherapy, a consensus regarding the optimal sequence of treatment has not yet been reached. Notwithstanding, sunitinib is largely used in these patients after the promising results shown in SUN111 phase III clinical trial. However, both prompt progression as well as tumor recurrence after initial response have been reported, suggesting the existence of primary and acquired resistances to this antiangiogenic drug. In this review, we aim to summarize the most relevant mechanisms of angiogenesis resistance that are key contributors of tumor progression and dissemination. Furthermore, several targeted molecules acting selectively against these pathways have shown promising results in preclinical models, and preliminary results from ongoing clinical trials are awaited.