Pembrolizumab monotherapy in patients with previously treated metastatic high-grade neuroendocrine neoplasms: joint analysis of two prospective, non-randomised trials. Br J Cancer. 2020;122:1309-1314. [PMID: 32152503 PMCID: PMC7188798 DOI: 10.1038/s41416-020-0775-0]

Liver Transplantation for Non-hepatocellular Carcinoma: The Role of Immune Checkpoint Inhibitors

Colorectal cancer (CRC), gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN), and cholangiocarcinoma (CCA) exhibit high rates of morbidity and mortality once metastasized to the liver. Liver transplantation (LT) is a viable therapeutic approach for these cancers in highly selected patients; however, their invasive nature at late stages causes many patients to be delisted from transplantation or to require further downstaging. Immunotherapy with immune checkpoint modulators has revolutionized cancer research. Immune checkpoint inhibitors (ICI) leverage the chronic inflammatory state and the overexpression of cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) by malignant cells and regulatory T cells, to block immune checkpoints and counteract tumor's ability to evade the immune system. However, the interaction between allograft PD-L1 and PD-1 on infiltrating T cells functions as a means of graft tolerance in cases of LT. Therefore, the application of ICIs might block this protective effect and induce graft rejection, a phenomenon particularly observed in PD-1/PD-L1 inhibiting ICIs. The risk of post-LT graft rejection can be mitigated by applying advanced biomarkers and specifying certain mutations that enhance patient selection criteria for pre-LT ICI use. Furthermore, the determination of optimal intervals of ICI administration pre- and post-LT, identification of ICI indications in de novo malignancies occurring after LT, and investigation of biomarkers for early rejection detection, pave the way for more promising LT outcomes in patients with CRC, GEP-NEN, or CCA. Therefore, this review aims to illustrate a comprehensive overview of the role of ICI therapy in the management of non-hepatocellular carcinoma transplant oncology cancers by demonstrating the potential for its application in both pre-and post-LT states, and pathways to reduce or timely detect ICI-associated graft rejection.

Combining anti-PD-1 antibodies with surufatinib for gastrointestinal neuroendocrine carcinoma: Two cases report and review of literature

BACKGROUND

Gastrointestinal neuroendocrine carcinoma (GI NEC) has a low incidence rate and poor prognosis. Most patients already have metastatic disease when they are diagnosed. Platinum chemotherapy is the main means of treating metastatic GI NECs. There is a lack of effective treatment methods after chemotherapy failure. Therefore, Therefore, selecting appropriate posterior-line treatment programs to improve the prognosis of patients is urgently needed.

CASE SUMMARY

A 64-year-old female was diagnosed with stage IV NEC of the rectum due to abdominal pain and rectal bleeding. After multiline chemotherapy, the condition progressed, and the patient was treated with a combination of camrelizumab and surufatinib. The efficacy evaluation revealed partial remission (PR) and stable conditions, with the expression of the tumor marker neuron-specific enolase (NSE) returning to normal. The adverse reactions were controllable, and the overall condition was good, with weight gain achieved in the past four years. Another 51-year-old female experienced recurrence and metastasis of a duodenal NEC after surgery. After multiline chemotherapy, she received sintilimab combined with surufatinib. The curative effect fluctuated between PR and stability. During treatment, she recovered from immune-related diabetes and later died due to deterioration of her condition. During the treatment, the patient's NSE level returned to normal.

CONCLUSION

The combination of antiangiogenic targeted drugs and immunotherapy provides a new therapeutic approach for the treatment of metastatic GI-NECs.

Phase Ib/II study of Pembrolizumab with Lanreotide depot for advanced, progressive Gastroenteropancreatic neuroendocrine tumors (PLANET)

While performing a study of immune checkpoint blockade with the anti-PD-1 antibody pembrolizumab combined with the somatostatin analogue (SSA) lanreotide in patients with low- and intermediate-grade gastroenteropancreatic neuroendocrine tumors (GEP-NETs), we studied whether there were any immune correlates of response to the anti-PD-1 therapy that could guide future attempts to integrate immunotherapy into the treatment of NETs. Patients with grade 1 and 2 GEP-NETs who had progressed on a prior SSA received lanreotide 90 mg subcutaneously and pembrolizumab 200 mg intravenously every 3 weeks until progression or intolerable toxicity. Objective response rate (ORR) at any time in the study, clinical benefit rate (CBR, defined as stable disease or better), progression-free survival (PFS), and overall survival (OS) were measured. Changes in T cell subsets in peripheral blood before and during therapy were analyzed by multiparameter mass cytometry (CyTOF). Archived tissue samples were analyzed for PD-L1 expression and TIL infiltration. Twenty-two (22) patients (GI/pancreatic 14/8, median Ki67 7% [IQR 4, 10%], median 1.5 prior systemic therapies [range 1-4]) were enrolled. Among the GI-NETs, there was one partial response, the CBR was 50%, the median PFS was 8.5 months, and the median OS was 32.7 months. No responses were seen in pancreatic NETs, which had 0% CBR, a PFS of 2.7 months, and an OS of 23.9 months. Of the 16 analyzable tumors, 6 had detectable PD-L1 expression and 15 had detectable TILs. Neither TILs nor PD-L1 expression correlated with ORR or CBR. However, clinical benefit (SD or better) was associated with peripheral blood on-treatment effector memory T cell activation and progressive disease was associated with baseline peripheral blood regulatory T cell (Treg) activation. We conclude that immune checkpoint blockade had low activity in unselected patients with grade 1 and 2 GEP-NETs. Further study of strategies to reduce Treg activation or enhance effector memory activation during immunotherapy is warranted.

Activity and Safety of Avelumab in High-Grade Neuroendocrine Tumors and Poorly Differentiated Neuroendocrine Carcinomas Progressive after Chemotherapy (AveNEC Trial)

PURPOSE

Neuroendocrine neoplasms grade 3 (NEN G3) are rare tumors with poor prognosis and no established second-line therapy. The role of immune checkpoint blockade in these aggressive tumors remains unclear.

PATIENTS AND METHODS

The phase II AveNEC study evaluated the effect of avelumab (AVE, 10 mg/kg i.v. every 2 weeks) in 60 patients with well-differentiated high-grade neuroendocrine tumors (N = 22) or poorly differentiated neuroendocrine carcinomas (N = 38) progressing after ≥1 prior chemotherapy (excluding Merkel cell carcinoma and small cell lung cancer).

RESULTS

The best overall response according to immune-related Response Evaluation Criteria in Solid Tumors (iRECIST) was partial response (PR) in three (5%) and stable disease (SD) in nine (15%) patients, with a disease control rate at 16 weeks of 15% (3 PRs; 6 SDs) and a median duration of response of 4.3 months. Six (10%) patients achieved SD or PR for >6 months and two for >1 year. Response rates were similar regardless of differentiation, Ki-67 expression, or primary localization. The median progression-free survival was 1.9 months, and the overall survival was 6.6 months. After a median follow-up of 3.6 years, only four (7%) patients were still alive; 1- and 2-year survival rates were 33% and 17%, respectively. Responders had a significantly longer overall survival of 30.2 months compared with 4.8 months in nonresponders. AVE was well tolerated, with few treatment-related grade 3/4 adverse events, and the quality of life remained stable during treatment.

CONCLUSIONS

In patients with progressive high-grade NEN G3, AVE was well tolerated and provided disease control with significant clinical benefit in 15% of heavily pretreated patients.

Optimal early endpoint for second-line or subsequent immune checkpoint inhibitors in previously treated advanced solid cancers: a systematic review

BACKGROUND

The administration of second-line or subsequent immune checkpoint inhibitors (ICIs) in previously treated patients with advanced solid cancers has been clinically investigated. However, previous clinical trials lacked an appropriate primary endpoint for efficacy assessment. This systematic review aimed to explore the most optimal early efficacy endpoint for such trials.

METHODS

Phase 2 or 3 clinical trials involving patients with advanced solid cancers with disease progression following standard first-line therapy receiving second-line or subsequent ICI administration, with adequate survival outcome data, were included from PubMed, Embase, Web of Science, and Cochrane Library databases before February 2023. Quality assessment was conducted using the Cochrane tool and Newcastle-Ottawa Quality Assessment Scale for Cohort Studies for randomized controlled trials (RCTs) and non-randomized trials, respectively. Objective response rate (ORR) and progression-free survival (PFS) at 3, 6, and 9 months were investigated as potential early efficacy endpoint candidates for 12-month overall survival (OS), with a strong correlation defined as Pearson's correlation coefficient r ≥ 0.8.

RESULTS

A total of 64 RCTs comprising 22,725 patients and 106 non-randomized prospective trials involving 10,608 participants were eligible for modeling and external validation, respectively. RCTs examined 15 different cancer types, predominantly non-small-cell lung cancer (NSCLC) (17, 28%), melanoma (9, 14%), and esophageal squamous cell carcinoma (5, 8%). The median sample size of RCTs was 124 patients, and the median follow-up time was 3.2-57.7 months. The ORR (r = 0.38; 95% confidence interval [CI], 0.18-0.54) and PFS (r = 0.42; 95% CI, 0.14-0.64) exhibited weak trial-level correlations with OS. Within ICI treatment arms, the r values of ORR and 3-, 6-, and 9-month PFS with 12-month OS were 0.61 (95% CI, 0.37-0.79), 0.78 (95% CI, 0.62-0.88), 0.84 (95% CI, 0.77-0.90), and 0.86 (95% CI, 0.79-0.90), respectively. External validation of 6-month PFS indicated an acceptable discrepancy between actual and predicted 12-month OS.

CONCLUSIONS

In non-randomized phase 2 trials on second-line or subsequent ICI therapy in patients with advanced solid cancers, 6-month PFS could serve as an early efficacy endpoint. However, early efficacy endpoints are not recommended in RCTs to replace OS.

Everolimus in the Treatment of Neuroendocrine Tumors: Lights and Shadows

Neuroendocrine tumors (NETs) comprise a heterogeneous group of neoplasms that originate from neuroendocrine cells, characterized by their ability to secrete hormones and peptides. Once considered rare, the incidence of NETs has steadily increased due to improved diagnostic modalities. The therapeutic landscape is multifaceted, ranging from surgery for localized disease to pharmacological interventions for advanced cases. However, the absence of robust predictive biomarkers precludes patient stratification and optimization of therapy. Everolimus, an oral mTOR inhibitor, has emerged as a key therapeutic agent due to its dual role in inhibiting cell proliferation and angiogenesis. Nevertheless, challenges such as resistance mechanisms, toxicity and optimal treatment sequencing remain unresolved. This article provides a comprehensive review of the role of everolimus in the management of NETs, focusing in particular on unresolved issues, from the absence of predictive biomarkers to the unavailability of defined guidelines for determining the correct therapeutic sequence.

Unraveling the mysteries of MGMT: Implications for neuroendocrine tumors

Neuroendocrine tumors (NETs) are a diverse group of tumors that arise from neuroendocrine cells and are commonly found in various organs. A considerable proportion of NET patients were diagnosed at an advanced or metastatic stage. Alkylating agents are the primary treatment for NET, and O6-methylguanine methyltransferase (MGMT) remains the first-line of defense against DNA damage caused by these agents. Clinical trials have indicated that MGMT promoter methylation or its low/lacked expression can predict a favorable outcome with Temozolomide in NETs. Its status could help select NET patients who can benefit from alkylating agents. Therefore, MGMT status serves as a biomarker to guide decisions on the efficacy of Temozolomide as a personalized treatment option. Additionally, delving into the regulatory mechanisms of MGMT status can lead to the development of MGMT-targeted therapies, benefiting individuals with high levels of MGMT expression. This review aims to explore the polymorphism of MGMT regulation and summarize its clinical implications in NETs, which would help establish the role of MGMT as a biomarker and its potential as a therapeutic target in NETs. Additionally, we explore the benefits of combining Temozolomide and immunotherapy in MGMT hypermethylated subgroups. Future studies can focus on optimizing Temozolomide administration to induce specific immunomodulatory changes.

PD-L1 expression, tumor-infiltrating lymphocytes, and mismatch repair proteins status in digestive neuroendocrine neoplasms: exploring their potential role as theragnostic and prognostic biomarkers

Theragnostic biomarkers are still needed to select patients with digestive neuroendocrine neoplasms (NENs) for an optimal management. The PD-1/PD-L1 pathway plays a pivotal role in T cells activation and host immune response to cancer and PD-L1 expression in tumor and/or immune cells is used to identify patients who would benefit of treatment with immune checkpoint inhibitors. However, its role as a biomarker is still unclear in digestive NENs. We investigated PD-L1 expression in 68 well-characterized digestive NENs (32 NETs, 32 NECs and 4 MiNENs) and TPS and CPS scores were calculated. In addition, tumor infiltrating T-lymphocytes and mismatch repair protein expression (MMR) were evaluated. All results were correlated with clinicopathological features. PD-L1 expression was higher in NECs than in NETs: TPS > 1% and/or CPS > 1 were observed in 16% of NETs, 68.8% of NECs and 50% of MiNENs (p: 0.05). The mean TPS score in positive cases was 6.3% in NETs, 16.2% in NECs and 5% in MiNENs. The CPS score was 4.8 in NETs, 8.1 in NECs and 6 in MiNENs. MMR-deficient neoplasms were more frequently observed in NECs than in NETs (p: < 0.05) as well as intra-tumor immune infiltration (p: 0.00001). No correlation between PD-L1 expression and survival or other clinicopathological parameters was observed. Our results suggest that treatment with immune checkpoint inhibitors may have a potential role only in selected cases, mainly in NECs and MiNENs.

Gastroenteropancreatic neuroendocrine neoplasms: epidemiology, genetics, and treatment

The incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP NEN) is increasing at a rapid pace and is becoming an increasingly important consideration in clinical care. Epidemiological data from multiple countries indicate that the incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP NEN) exhibits regional, site-specific, and gender-based variations. While the genetics and pathogenesis of some GEP NEN, particularly pancreatic NENs, have been investigated, there are still many mechanisms that require further investigation. The management of GEP NEN is diverse, but surgery remains the primary option for most cases. Peptide receptor radionuclide therapy (PRRT) is an effective treatment, and several clinical trials are exploring the potential of immunotherapy and targeted therapy, as well as combination therapy.

Comprehensive genomic and transcriptomic characterization of high-grade gastro-entero-pancreatic neoplasms

BACKGROUND

High-grade gastro-entero-pancreatic neoplasms (HG GEP-NENs) can be stratified according to their morphology and Ki-67 values into three prognostic classes: neuroendocrine tumors grade 3 (NETs G3), neuroendocrine carcinomas with Ki-67 < 55% (NECs <55) and NECs with Ki-67 ≥ 55% (NECs ≥55).

METHODS

We analyzed a cohort of 49 HG GEP-NENs by targeted Next-Generation Sequencing (TrueSight Oncology 500), RNA-seq, and immunohistochemistry for p53, Rb1, SSTR-2A, and PD-L1.

RESULTS

Frequent genomic alterations affected TP53 (26%), APC (20%), KRAS and MEN1 (both 11%) genes. NET G3 were enriched in MEN1 (p = 0.02) mutations, while both NECs groups were enriched in TP53 (p = 0.001), APC (p = 0.002) and KRAS (p = 0.02) mutations and tumors with TMB ≥ 10 muts/Mb (p = 0.01). No differentially expressed (DE) gene was found between NECs <55% and NECs ≥55%, while 1129 DE genes were identified between NET G3 and NECs. A slight enrichment of CD4+ and CD8+ T cells in NECs and of cancer-associated fibroblasts and macrophages (M2-like) in NET G3. Multivariate analysis identified histologic type and Rb1 loss as independent prognostic factors for overall survival.

CONCLUSIONS

This study showed that GEP-NET G3 and GEP-NECs exhibit clear genomic and transcriptomic differences, differently from GEP-NECs <55% and GEP-NECs ≥55%, and provided molecular findings with prognostic and potentially predictive value.

Emerging Treatment Options for Neuroendocrine Neoplasms of Unknown Primary Origin: Current Evidence and Future Perspectives

Among neuroendocrine neoplasms (NENs), a non-negligible proportion (9-22%) is represented by sufferers of NENs of unknown primary origin (UPO), a poor prognostic group with largely unmet clinical needs. In the absence of standard therapeutic algorithms, current guidelines suggest that the treatment of UPO-NENs should be based on tumor clinical-pathological characteristics, disease burden, and patient conditions. Chemotherapy represents the backbone for the treatment of high-grade poorly differentiated UPO-NENs, usually providing deep but short-lasting responses. Conversely, the spectrum of available systemic therapy options for well-differentiated UPO-NENs may range from somatostatin analogs in indolent low-grade tumors, to peptide receptor radioligand therapy, tyrosine kinase inhibitors (TKIs), or chemotherapy for more aggressive tumors or in case of high disease burden. In recent years, molecular profiling has provided deep insights into the molecular landscape of UPO-NENs, with both diagnostic and therapeutic implications. Although preliminary, interesting activity data have been provided about upfront chemoimmunotherapy, the use of immune checkpoint inhibitors (ICIs), and the combination of ICIs plus TKIs in this setting. Here, we review the literature from the last 30 years to examine the available evidence about the treatment of UPO-NENs, with a particular focus on future perspectives, including the expanding scenario of targeted agents in this setting.

Phase II study of pembrolizumab and lenvatinib in advanced well-differentiated neuroendocrine tumors

BACKGROUND

Immune checkpoint inhibitors (CPIs) have not been shown to be active in well-differentiated neuroendocrine tumors (NETs), with response rates <5%. Lenvatinib is a multitargeted tyrosine kinase inhibitor which binds to vascular endothelial growth factor and fibroblast growth factor receptors and has demonstrated efficacy in pancreatic and gastrointestinal NETs [44% and 16% objective radiographic response rate (ORR), respectively]. The combination of antiangiogenic and CPI therapies can be synergistic. We therefore evaluated the combination of lenvatinib and pembrolizumab in well-differentiated gastrointestinal (GI) and thoracic NETs.

PATIENTS AND METHODS

A prospective, phase II trial evaluated patients with advanced GI/thoracic NETs (pancreatic NETs were excluded due to high response rate of lenvatinib monotherapy in this patient population), with evidence of progression within 8 months of study entry and at least two prior lines of systemic therapy. Patients received lenvatinib 20 mg daily and pembrolizumab 200 mg intravenously every 3 weeks until unacceptable toxicity or progression of disease. Primary endpoint was objective response rate, and an interim analysis was planned once 20 patients were enrolled. Four ORRs were required to continue enrollment.

RESULTS

Twenty patients were enrolled on protocol from April 2021 to January 2022 (nine small intestine, five lung, two thymic, two unknown primary, one cecal, one presacral primaries). Two patients (10%) achieved a partial response (atypical lung and small intestinal primaries). Median progression-free survival (PFS) was 8 months (95% confidence interval 5.8-10.2 months). Twelve (60%) patients experienced probably or definitely associated grade 3 adverse events (10 hypertension). Fourteen patients (70%) required dose reductions or discontinued one of the medications. Two patients discontinued treatment before radiographic assessment.

CONCLUSIONS

The combination of pembrolizumab and lenvatinib did not show sufficient response in patients with NETs to warrant continued enrollment on trial.

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.

Spatial profiling reveals tissue-specific neuro-immune interactions in gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are heterogeneous malignancies that arise from complex cellular interactions within the tissue microenvironment. Here, we sought to decipher tumor-derived signals from the surrounding microenvironment by applying digital spatial profiling (DSP) to hormone-secreting and non-functional GEP-NETs. By combining this approach with in vitro studies of human-derived organoids, we demonstrated the convergence of cell autonomous immune and pro-inflammatory proteins that suggests their role in neuroendocrine differentiation and tumorigenesis. DSP was used to evaluate the expression of 40 neural- and immune-related proteins in surgically resected duodenal and pancreatic NETs (n = 20) primarily consisting of gastrinomas (18/20). A total of 279 regions of interest were examined between tumors, adjacent normal and abnormal-appearing epithelium, and the surrounding stroma. The results were stratified by tissue type and multiple endocrine neoplasia I (MEN1) status, whereas protein expression was validated by immunohistochemistry (IHC). A tumor immune cell autonomous inflammatory signature was further evaluated by IHC and RNAscope, while functional pro-inflammatory signaling was confirmed using patient-derived duodenal organoids. Gastrin-secreting and non-functional pancreatic NETs showed a higher abundance of immune cell markers and immune infiltrate compared with duodenal gastrinomas. Compared with non-MEN1 tumors, MEN1 gastrinomas and preneoplastic lesions showed strong immune exclusion and upregulated expression of neuropathological proteins. Despite a paucity of immune cells, duodenal gastrinomas expressed the pro-inflammatory and pro-neural factor IL-17B. Treatment of human duodenal organoids with IL-17B activated NF-κB and STAT3 signaling and induced the expression of neuroendocrine markers. In conclusion, multiplexed spatial protein analysis identified tissue-specific neuro-immune signatures in GEP-NETs. Duodenal gastrinomas are characterized by an immunologically cold microenvironment that permits cellular reprogramming and neoplastic transformation of the preneoplastic epithelium. Moreover, duodenal gastrinomas cell autonomously express immune and pro-inflammatory factors, including tumor-derived IL-17B, that stimulate the neuroendocrine phenotype. © 2024 The Pathological Society of Great Britain and Ireland.

Retrospective Analyses of PD-L1, LAG-3, TIM-3, OX40L Expressions and MSI Status in Gastroenteropancreatic Neuroendocrine Neoplasms

We investigated expressions of PD-L1, LAG-3, TIM-3, and OX40L as immune checkpoint proteins, and MSI (repetitive short-DNA-sequences due to defective DNA-repair system) status were analyzed with immunohistochemistry from tissue blocks. Of 83 patients, PD-L1 expression was observed in 18.1% (n = 15) of the patients. None of the patients exhibited LAG-3 expression. TIM-3 expression was 4.9% (n = 4), OX40L was 22.9% (n = 19), and 8.4% (n = 7) of the patients had MSI tumor. A low-to-intermediate positive correlation was observed between PD-L1 and TIM-3 expressions (rho: 0.333, p < 0.01). Although PD-L1 expression was higher in grade 3 NET/NEC, MSI status was prominent in grade 1/2 NET.

Peptide receptor radionuclide therapy combinations for neuroendocrine tumours in ongoing clinical trials: status 2023

A growing body of literature reports on the combined use of peptide receptor radionuclide therapy (PRRT) with other anti-tumuor therapies in order to anticipate synergistic effects with perhaps increased safety issues. Combination treatments to enhance PRRT outcome are based on improved tumour perfusion, upregulation of somatostatin receptors (SSTR), radiosensitization with DNA damaging agents or targeted therapies. Several Phase 1 or 2 trials are currently recruiting patients in combined regimens. The combination of PRRT with cytotoxic chemotherapy, capecitabine and temozolomide (CAPTEM), seems to become clinically useful especially in pancreatic neuroendocrine tumours (pNETs) with acceptable safety profile. Neoadjuvant PRRT prior to surgery, PRRT combinations of intravenous and intraarterial routes of application, combinations of PRRT with differently radiolabelled (alpha, beta, Auger) SSTR-targeting agonists and antagonists, inhibitors of immune checkpoints (ICIs), poly (ADP-ribose) polymerase-1 (PARP1i), tyrosine kinase (TKI), DNA-dependent protein kinase, ribonucleotide reductase or DNA methyltransferase (DMNT) are tested in currently ongoing clinical trials. The combination with [131I]I-MIBG in rare NETs (such as paraganglioma, pheochromocytoma) and new non-SSTR-targeting radioligands are used in the personalization process of treatment. The present review will provide an overview of the current status of ongoing PRRT combination treatments.

Targeted radionuclide therapy in endocrine-related cancers: advances in the last decade

Targeted radionuclide therapy plays an increasingly important role in managing endocrine-related tumors and significantly advances the therapeutic landscape for patients with these diseases. With increasing FDA-approved therapies and advances in the field, come an increased knowledge of the potential for long-term toxicities associated with these therapies and the field must develop new strategies to increase potency and efficacy while individualizing the selection of patients to those most likely to respond to treatment. Novel agents and modalities of therapy are also being explored. This review will discuss the current landscape and describe the avenues for growth in the field currently being explored.

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

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

Gastric neuroendocrine carcinoma presenting complete durable response by nivolumab treatment for multiple metastases and radiotherapy to oligoprogressive metastasis

Gastric neuroendocrine carcinomas (NEC) are highly aggressive cancer with dismal prognosis. Platinum-based chemotherapy is used as the first-line treatment for this entity. However, there are no established therapeutic guidelines for platinum-resistant gastric NEC. We herein report a patient with metastatic gastric NEC who achieved durable and complete response to nivolumab with radiotherapy for oligoprogressive metastasis. A 70-year-old male patient had recurrences of resected gastric NEC, involving the liver and lymph nodes. His disease became refractory to cisplatin and etoposide combination therapy, after which he was treated with nivolumab. All the tumors showed marked shrinkage. However, 1 year after starting nivolumab, one metastatic lesion of the liver began to enlarge, and radiotherapy was performed to the lesion. Thereafter, a complete response was obtained, which has been maintained without any treatment for the past 2 years.

Managing Metastatic Extrapulmonary Neuroendocrine Carcinoma After First-Line Treatment

PURPOSE OF REVIEW

Extrapulmonary neuroendocrine carcinoma (EP-NEC) is a rare, aggressive malignancy that can arise from any organ and frequently presents with distant metastases. Advanced disease has a poor prognosis with median overall survival (OS) rarely exceeding 1 year even with systemic therapy. The management paradigm of advanced/metastatic EP-NEC has been extrapolated from small cell lung cancer (SCLC) and commonly consists of 1st line therapy with etoposide and platinum (cisplatin or carboplatin), followed by alternative cytotoxic regimens at the time of progression. Only a minority of patients are able to receive 2nd line therapy, and cytotoxics derived from the SCLC paradigm such as topotecan or lurbinectedin have very limited activity. We aimed to evaluate emerging therapeutic options in the 2nd and later lines and survey potential future developments in this space.

RECENT FINDINGS

After a long period of stagnation in treatment options and outcomes, more promising regimens are gradually being utilized in the 2nd line setting including systemic therapy combinations such as FOLFIRI, FOLFOX, modified FOLFIRINOX, CAPTEM, and, more recently, novel checkpoint inhibitors such as nivolumab and ipilimumab. Simultaneously, advances in the understanding of disease biology are helping to refine patient selection and identify commonalities between NEC and their sites of origin which may eventually lead to additional targeted therapy options. While many questions remain, contemporary developments give grounds for optimism that improved outcomes for EP-NEC will soon be within reach.

Narrative Review of Immunotherapy in Gastroentero-Pancreatic Neuroendocrine Neoplasms

Gastroentero-pancreatic Neuroendocrine Neoplasms (GEP-NENs) are a diverse group of rare tumors that arise from neuroendocrine cells in the gastrointestinal tract and pancreas, and they can vary significantly in terms of clinical behavior and prognosis. Immunotherapy, particularly immune checkpoint inhibitors, has shown remarkable success in various malignancies by harnessing the body's immune system to target and eliminate cancer cells. Immune checkpoint inhibitor clinical studies in GEP-NENs have yielded promising outcomes, particularly in individuals with advanced and refractory disease. Objective responses and disease stabilization have been observed in some cases, even in those previously unresponsive to traditional treatments like chemotherapy or targeted therapies. However, it's important to note that the efficacy of immunotherapy in GEP-NENs can vary widely depending on tumor characteristics, the immune microenvironment, and patient factors. As such, identifying predictive biomarkers to select the most suitable patients for immunotherapy remains an ongoing challenge. Immunotherapy has considerable potential for treating GEP-NENs, but research is still in its early stages. Several combinations are being explored to enhance the effectiveness of immunotherapy and improve the outcomes of treatment, such as combining immunotherapy with other targeted therapies or chemotherapy.

Consensus report of the 2021 National Cancer Institute neuroendocrine tumor clinical trials planning meeting

Important progress has been made over the last decade in the classification, imaging, and treatment of neuroendocrine neoplasm (NENs), with several new agents approved for use. Although the treatment options available for patients with well-differentiated neuroendocrine tumors (NETs) have greatly expanded, the rapidly changing landscape has presented several unanswered questions about how best to optimize, sequence, and individualize therapy. Perhaps the most important development over the last decade has been the approval of 177Lu-DOTATATE for treatment of gastroenteropancreatic-NETs, raising questions around optimal sequencing of peptide receptor radionuclide therapy (PRRT) relative to other therapeutic options, the role of re-treatment with PRRT, and whether PRRT can be further optimized through use of dosimetry among other approaches. The NET Task Force of the National Cancer Institute GI Steering Committee convened a clinical trial planning meeting in 2021 with multidisciplinary experts from academia, the federal government, industry, and patient advocates to develop NET clinical trials in the era of PRRT. Key clinical trial recommendations for development included 1) PRRT re-treatment, 2) PRRT and immunotherapy combinations, 3) PRRT and DNA damage repair inhibitor combinations, 4) treatment for liver-dominant disease, 5) treatment for PRRT-resistant disease, and 6) dosimetry-modified PRRT.

Potent molecular-targeted therapies for gastro-entero-pancreatic neuroendocrine carcinoma

Neuroendocrine neoplasms (NENs), which are characterized by neuroendocrine differentiation, can arise in various organs. NENs have been divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs) based on morphological differentiation, each of which has a distinct etiology, molecular profile, and clinicopathological features. While the majority of NECs originate in the pulmonary organs, extrapulmonary NECs occur most predominantly in the gastro-entero-pancreatic (GEP) system. Although platinum-based chemotherapy is the main therapeutic option for recurrent or metastatic GEP-NEC patients, the clinical benefits are limited and associated with a poor prognosis, indicating the clinically urgent need for effective therapeutic agents. The clinical development of molecular-targeted therapies has been hampered due to the rarity of GEP-NECs and the paucity of knowledge on their biology. In this review, we summarize the biology, current treatments, and molecular profiles of GEP-NECs based on the findings of pivotal comprehensive molecular analyses; we also highlight potent therapeutic targets for future precision medicine based on the most recent results of clinical trials.

Tumor mutation burden in gastro-entero-pancreatic-neuroendocrine neoplasms

Background

As rare tumors, there are limited treatment options for neuroendocrine neoplasms (NENs). Recently, microsatellite instability (MSI) and tumor mutation burden (TMB) have been emerging as potential biomarkers in various tumors. However, there is a lack of research on the use of these biomarkers in gastro-entero-pancreatic (GEP)-NENs.

Methods

We analyzed 31 patients diagnosed with GEP-NEN between 2013 to 2022. The TMB and MSI analyses using next-generation sequencing (NGS) were performed for all patients. The TruSightTM Oncology 500 assay from Illumina was used as the NGS panel.

Results

Out of the 31 patients analyzed, the most frequent primary origin was the pancreas (12 patients, 38.7%), followed by the stomach (4 patients, 12.9%), gallbladder (4 patients, 12.9%), rectum (7 patients, 22.6%), small bowel (2 patients, 6.5%), and bile duct (1 patient, 3.2%). Among these patients, 19 (61.3%) were diagnosed with well-differentiated neuroendocrine tumors, with grade 2 being the most common (15 patients, 48.4%), followed by grade 3 (3 patients, 9.7%) and grade 1 (1 patient, 3.2%). Neuroendocrine carcinoma was confirmed in 12 patients (38.7%). The median number of metastases was 2.0 [interquartile range (IQR), 1.0-3.0], and the liver was the most common site of metastasis (23 patients, 74.2%). The median TMB was 4.7 (IQR, 3.1-6.3) mutations/Mb, and all tumors were classified as microsatellite stability (MSS). Only one patient had a high TMB (266.4 mutations/Mb), which was a grade 3 neuroendocrine tumor originating from the pancreas. The TMB value did not vary depending on the primary tumor site or World Health Organization (WHO) grade.

Conclusions

This analysis showed that, despite very low incidence, there are GEP-NENs with high TMB. For precision medicine, testing for MSI and TMB is needed for this tumor type.

Digestive MiNENs: Could histological classification and molecular characterization drive clinical outcome and therapeutic approach?

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are epithelial neoplasms in which neuroendocrine and non-neuroendocrine discrete components are combined, each of which constitutes ≥ 30% of the neoplasm. The finding of an additional neuroendocrine component seems to characterize the tumor's biological behavior. Few studies have proved MiNENs histogenetic and molecular characterization, and the development of molecular markers for more accurate classification of MiNENs represents a clinical need. However, a common origin of the neuroendocrine and non-neuroendocrine components from a pluripotent cancer stem cell could be suggested. The optimal clinical management of MiNENS is largely unknown. Whenever feasible, curative-intent resection should be performed for localized disease; in advanced disease, the treatment should be targeted to the component responsible for the metastatic spreading. This paper provides a revision of the current knowledge on MiNENs, focusing on available evidence about their molecular characterization to suggest a prognostic stratification of these rare forms.

Expert Consensus Practice Recommendations of the North American Neuroendocrine Tumor Society for the management of high grade gastroenteropancreatic and gynecologic neuroendocrine neoplasms

High-grade neuroendocrine neoplasms are a rare disease entity and account for approximately 10% of all neuroendocrine neoplasms. Because of their rarity, there is an overall lack of prospectively collected data available to advise practitioners as to how best to manage these patients. As a result, best practices are largely based on expert opinion. Recently, a distinction was made between well-differentiated high-grade (G3) neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas, and with this, pathologic details, appropriate imaging practices and treatment have become more complex. In an effort to provide practitioners with the best guidance for the management of patients with high-grade neuroendocrine neoplasms of the gastrointestinal tract, pancreas, and gynecologic system, the North American Neuroendocrine Tumor Society convened a panel of experts to develop a set of recommendations and a treatment algorithm that may be used by practitioners for the care of these patients. Here, we provide consensus recommendations from the panel on pathology, imaging practices, management of localized disease, management of metastatic disease and surveillance and draw key distinctions as to the approach that should be utilized in patients with well-differentiated G3 neuroendocrine tumors vs poorly differentiated neuroendocrine carcinomas.

Pembrolizumab alone and pembrolizumab plus chemotherapy in previously treated, extrapulmonary poorly differentiated neuroendocrine carcinomas

BACKGROUND

To date, single-agent immune checkpoint inhibitor (CPI) therapy has proven to be ineffective against biomarker-unselected extrapulmonary poorly differentiated neuroendocrine carcinomas (EP-PDNECs). The efficacy of CPI in combination with chemotherapy remains under investigation.

METHODS

Patients with advanced, progressive EP-PDNECs were enrolled in a two-part study of pembrolizumab-based therapy. In Part A, patients received pembrolizumab alone. In Part B, patients received pembrolizumab plus chemotherapy.

PRIMARY ENDPOINT

objective response rate (ORR). Secondary endpoints: safety, progression-free survival (PFS) and overall survival (OS). Tumours were profiled for programmed death-ligand 1 expression, microsatellite-high/mismatch repair deficient status, mutational burden (TMB), genomic correlates. Tumour growth rate was evaluated.

RESULTS

Part A (N = 14): ORR (pembrolizumab alone) 7% (95% CI, 0.2-33.9%), median PFS 1.8 months (95% CI, 1.7-21.4), median OS 7.8 months (95% CI, 3.1-not reached); 14% of patients (N = 2) had grade 3/4 treatment-related adverse events (TRAEs). Part B (N = 22): ORR (pembrolizumab plus chemotherapy) 5% (95% CI, 0-22.8%), median PFS 2.0 months (95% CI, 1.9-3.4), median OS 4.8 months (95% CI, 4.1-8.2); 45% of patients (N = 10) had grade 3/4 TRAEs. The two patients with objective response had high-TMB tumours.

DISCUSSION

Treatment with pembrolizumab alone and pembrolizumab plus chemotherapy was ineffective in advanced, progressive EP-PDNECs.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT03136055.

Progress in immunotherapy for neuroendocrine neoplasm of the digestive system

Neuroendocrine neoplasms (NENs) are rare heterogeneous tumors that can develop in almost any organ, with the digestive organs, including the gastrointestinal tract and pancreas being the most commonly affected sites. Despite the fact that advances in initial therapies have progressed, there is presently no recognized effective treatment for advanced NEN. Immune checkpoint inhibitors (ICIs) have shown superior efficacy in treating several types of solid tumors. Despite their successful role in the treatment of partial NENs, such as small cell lung cancer, and Merkel cell carcinoma, the role of ICIs in most of the NENs remains limited. Nevertheless, due to their specific anti-tumor mechanisms and acceptable safety profile, ICIs are a promising avenue for further study in NENs therapy. Recent clinical trials have illustrated that combination therapy with ICI is more efficient than monotherapy, and multiple clinical trials are constantly ongoing to evaluate the efficacy and safety of these combination therapies. Therefore, the purpose of this review is to provide a comprehensive summary of the clinical progress of immunotherapy in NENs affecting the digestive system, with a specific emphasis on the application of programmed cell death protein 1/programmed death receptor ligand 1 inhibitor. Furthermore, this review has an exploration of the potential beneficiary population and the inherent value of utilizing immunotherapy in the management of NENs.

Addition of Peptide Receptor Radiotherapy to Immune Checkpoint Inhibition Therapy Improves Outcomes in Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are often diagnosed in advanced stages. Despite the advances in treatment approaches, including somatostatin analogs and peptide receptor radionuclide therapy (PRRT), these patients have no curative treatment option. Moreover, immunotherapy often yields modest results in NETs. We investigated whether combining PRRT using [177Lu]DOTATATE and immune checkpoint inhibition therapy improves treatment response in NETs. Methods: A gastroenteropancreatic NET model was generated by subcutaneous implantation of human QGP-1 cells in immune-reconstituted NOD.Cg-Prkdcscid Il2rgtm1Wjl /SzJ mice engrafted with human peripheral blood mononuclear cells (n = 96). Mice were randomly assigned to receive pembrolizumab (anti-PD1), [177Lu]DOTATATE (PRRT), simultaneous anti-PD1 and PRRT (S-PRRT), anti-PD1 on day 0 followed by PRRT on day 3 (delayed PRRT [D-PRRT]), PRRT on day 0 followed by anti-PD1 (early PRRT [E-PRRT]), or vehicle as control (n = 12/group). Human granzyme-B-specific [68Ga]NOTA-hGZP PET/MRI was performed before and 6 d after treatment initiation, as an indicator of T-cell activation. Response to treatment was based on tumor growth over 21 d and on histologic analyses of extracted tissues on flow cytometry for T cells, hematoxylin and eosin staining, and immunohistochemical staining. Results: [68Ga]NOTA-hGZP PET/MRI showed significantly increased uptake in tumors treated with E-PRRT, S-PRRT, and anti-PD1 on day 6 compared with baseline (SUVmax: 3.36 ± 0.42 vs. 0.73 ± 0.23; 2.36 ± 0.45 vs. 0.76 ± 0.30; 2.20 ± 0.20 vs. 0.72 ± 0.28, respectively; P < 0.001), whereas no significant change was seen in PET parameters in the D-PRRT, PRRT, or vehicle groups (P > 0.05). Ex vivo analyses confirmed the PET results showing the highest granzyme-B levels and T cells (specifically CD8-positive effector T cells) in the E-PRRT group, followed by the S-PRRT and anti-PD1 groups. Tumor growth follow-up showed the most significant tumor size reduction in the E-PRRT group (baseline to day 21, 205.00 ± 30.70 mm3 vs. 78.00 ± 11.75 mm3; P = 0.0074). Tumors showed less growth reduction in the PRRT, D-PRRT, and S-PRRT groups than in the E-PRRT group (P < 0.0001). The vehicle- and anti-PD-1-treated tumors showed continued growth. Conclusion: Combination of PRRT and anti-PD1 shows the most robust inflammatory response to NETs and a better overall outcome than immune checkpoint inhibition or PRRT alone. The most effective regimen is PRRT preceding anti-PD1 administration by several days.

Urinary Neuroendocrine Neoplasms Treated in the "Modern Era": A Multicenter Retrospective Review

BACKGROUND

Primary urinary neuroendocrine neoplasms (U-NENs) are extremely rare thus optimal treatment is unknown. Grading and treatment are typically extrapolated from other primary sites. Since 2010, the clinical landscape for NENs has changed substantially. We performed a retrospective review of U-NENs to assess treatment patterns and oncologic outcomes of patients treated in the recent era of NEN therapy.

PATIENTS AND METHODS

A multicenter retrospective review of patients diagnosed after 2005 and alive after 2010. Time to treatment failure (TTF) was used to evaluate progression and toxicity for systemic therapy. Tumors were categorized as having either well-differentiated neuroendocrine tumor (WDNET) or poorly differentiated neuroendocrine carcinoma (PDNEC) histology.

RESULTS

A total of 134 patients from 6 centers were included in our analysis, including 94 (70%) bladder, 32 (24%) kidney, 2 (1.5%) urethra and 4 other urinary primaries (3.0%). Poorly-differentiated neuroendocrine carcinoma was more common in bladder (92%) than non-bladder tumors (8%). Median Ki-67 available in bladder primary was 90% (n = 24), kidney 10% (n = 23), ureter 95% (n = 1), urethra 54% (n = 2), and others 90% (n = 3). Patients received a median of 2 therapies (range 0-10). Median time to death was not reached in locoregional WDNETs versus 8.2 years (95% CI, 3.5-noncalculable) in metastatic WDNETs (predominantly renal primary). Median time to death was 3.6 years (95% CI, 2.2-9.2) in locoregional PDNECs versus 1 year (95% CI, 0.8-1.3) in metastatic PDNECs (predominantly bladder primary).

CONCLUSION

This is the most extensive series examining treatment patterns in patients with U-NENs in the recent era of NEN therapy. The apparent inferior survival for bladder NENs is likely due to the preponderance of PDNECs in this group. As predicted, treatments for U-NENs mirrored that of other more common NENs. In our retrospective cohort, we observed that patients with WD-UNETs treated with peptide receptor radionuclide therapy (PRRT) and everolimus suggested potential activity for disease control in WD-UNETs. Prospective studies are needed to assess the activity of new oncology drugs in UNENs.

Clinical Behavior, Mutational Profile and T-Cell Repertoire of High-Grade Neuroendocrine Tumors of the Head and Neck

Neuroendocrine carcinomas (NECs) of the head and neck (HN) account for <1% of HN cancers (HNCs), with a 5-year overall survival (OS) <20%. This is a retrospective study of HN NECs diagnosed at our institution between 2005 and 2022. Immunohistochemistry and next-generation sequencing (NGS) were used to evaluate neuroendocrine markers, tumor mutational burden (TMB), mutational profiles and T-cell receptor repertoires. Eleven patients with high-grade HN NECs were identified (male:female ratio 6:5; median age 61 (Min-Max: 31-86)): nasoethmoidal (3), parotid gland (3), submaxillary gland (1), larynx (3) and base of tongue (1). Among n = 8 stage II/IVA/B, all received (chemo)radiotherapy with/without prior surgery or induction chemotherapy, with complete response in 7/8 (87.5%). Among n = 6 recurrent/metastatic patients, three received anti-PD1 (nivolumab (2), pembrolizumab (1)): two achieved partial responses lasting 24 and 10 months. After a median follow-up of 30 and 23.5 months since diagnosis and since recurrent/metastatic, median OS was not reached. Median TMB (n = 7) was 6.72 Mut/Mb. The most common pathogenic variants were TP53, HNF1A, SMARCB1, CDKN2A, PIK3CA, RB1 and MYC. There were 224 median TCR clones (n = 5 pts). In one patient, TCR clones increased from 59 to 1446 after nivolumab. HN NECs may achieve long-lasting survival with multimodality treatment. They harbor moderate-high TMBs and large TCR repertoires, which may explain responses to anti-PD1 agents in two patients and justify the study of immunotherapy in this disease.

Efficacy of first-line checkpoint inhibitors in combination with chemotherapy in high-grade extrapulmonary metastatic neuroendocrine carcinomas

Poorly differentiated extrapulmonary neuroendocrine carcinomas (EP NECs) are aggressive cancers characterized by a high Ki-67 index, rapid tumor growth and poor survival, and are subdivided into small and large cell carcinoma. For small cell carcinoma of the lung, a pulmonary NEC, the combination of cytotoxic chemotherapy (CTX) and a checkpoint inhibitor (CPI) is considered standard therapy and superior to CTX alone. EP NECs are typically treated with platinum-based regimens, some clinicians have adopted the addition of a CPI to CTX based on data from trials in patients with small cell carcinoma of the lung. In this retrospective study of EP NECs, we report 38 patients treated with standard first-line CTX and 19 patients treated with CTX plus CPI. We did not observe any additional benefit of adding CPI to CTX in this cohort.

Neuroendocrine Neoplasms of the Gastrointestinal Tract versus Neuroendocrine Neoplasms of the Gynaecological Tract-Comparison of the Risk Factors and Non-Surgical Treatment Efficacy

Neuroendocrine tumours of the gastrointestinal tract are rare. The incidence has increased in recent years due to improvements in diagnostic methods for detecting these lesions. These tumours have a poor prognosis, especially when detected at an advanced stage. The basis of the treatment is resection, and non-surgical treatments are also standard in the treatment process. The situation is similar in even rarer neuroendocrine tumours of the reproductive tract, which are associated with an equally poor prognosis. In this article, we focus on learning about the risk factors (including genetic mutations) that increase the risk of the disease and comparing the effectiveness of non-surgical treatments-chemotherapy, radiotherapy, peptide receptor radionuclide therapy, somatostatin analogues, and immunotherapy. The efficacy of these treatments varies, and immunotherapy appears to be a promising form of treatment; however, this requires further research.

A systematic review of therapeutic strategies in gastroenteropancreatic grade 3 neuroendocrine tumors

Background

Gastroenteropancreatic (GEP) neuroendocrine neoplasms with Ki-67 > 20% were subdivided in the most recent 2019 World Health Organization histopathological classification into grade 3 (G3) neuroendocrine tumors (NETs), described as well-differentiated tumors, and neuroendocrine carcinomas, which are described as poorly differentiated tumors. This classification met the demand noted for different prognoses between these subgroups, prompting the need for treatment recommendations for well-differentiated G3 tumors.

Methods

We systematically searched medical literature databases and oncology conferences for studies on G3 GEP NET to describe epidemiology, diagnosis, molecular features, and treatments used. We excluded studies that did not discriminate G3 NET data. Data were tabulated and described, and a quality analysis of the reports was performed.

Results

We found 23 published studies and six abstracts; 89.7% of studies were retrospective, six were composed exclusively of G3 NETs. Among 761 patients, the median number of patients per study was 15, most were male and older than 60 years, and functional imaging tests were positive in more than 80% of cases. Overall, the scientific evidence supporting the treatment of G3 GEP NETs is limited. For localized disease, resection remains the standard treatment but there is no evidence to support neoadjuvant or adjuvant therapy. For advanced disease, capecitabine and temozolomide seems to be the most effective option, with a response rate, median progression-free survival, and median overall survival up to 37.9%, 20.6 months, and 41.2 months, respectively.

Conclusion

The latest available data on the epidemiology, diagnosis, molecular changes, and treatment of G3 GEP NET are described. Yet, the level of evidence for treatment recommendations is low, as most studies are retrospective. A treatment algorithm for G3 GEP NET is proposed.

Comparative Outcomes of Second-line Topoisomerase-I Inhibitor Therapies on Neuroendocrine Carcinoma

INTRODUCTION

This investigation aims to assess the outcomes for second-line therapies to treat extrapulmonary neuroendocrine carcinoma (EP-NEC) after first-line platinum-based chemotherapy.

METHODS

With IRB approval, we conducted a retrospective study of EP-NEC patients that progressed on first-line platinum chemotherapy from 2008 to 2018. Demographic data and treatment-related characteristics were collected and represented as descriptive statistics. The primary endpoints include overall survival (OS) and progression-free survival (PFS). OS and PFS were estimated and stratified by site of primary (gastroenteropancreatic [GEP] versus non-GEP) and type of second-line therapy (irino/topotecan versus others). Log-rank test and Kaplan-Meier curves were used to compare survival distributions between groups.

RESULTS

Forty-seven patients met eligibility, with median age 65 (range 31-82), 62% male, and 83% White; 22 were GEP and 25 were non-GEP primary. Thirty patients (63.8%) received second-line therapy where 11 received irinotecan/topotecan (ir/to), while 19 received other agents (temozolomide, other platinum agents, gemcitabine, paclitaxel, pembrolizumab, and sunitinib). The median OS was 10.3 months in the ir/to group versus 13.4 months for other therapies, p = 0.10. The median PFS for ir/to therapy compared to other therapies was 2.0 months versus 1.8 months, respectively, p = 0.72. The OS and PFS with and without ir/to were not significantly different by the primary site (p = 0.61 and p = 0.21).

DISCUSSION/CONCLUSION

Many EP-NEC patients undergo second-line therapies. Interestingly, outcomes for ir/to-containing second-line therapies were not statistically different from other agents, regardless of the site of primary. With approval of new second-line therapies for small cell lung cancer, further research in therapeutic options is needed for this aggressive disease.

Future therapeutic strategies in the treatment of extrapulmonary neuroendocrine carcinoma: a review

Neuroendocrine neoplasms (NENs) are rare malignancies arising most commonly in the gastrointestinal and bronchopulmonary systems. Neuroendocrine carcinomas (NECs) are a subgroup of NENs characterised by aggressive tumour biology, poor differentiation and dismal prognosis. Most NEC primary lesions arise in the pulmonary system. However, a small proportion arise outside of the lung and are termed extrapulmonary (EP)-, poorly differentiated (PD)-NECs. Patients with local or locoregional disease may benefit from surgical excision; however, this is often not an option, due to late presentation. To date, treatment has mirrored that of small-cell lung cancer, with platinum-etoposide forming the basis of first-line treatment. There is a lack of consensus in relation to the most effective second-line treatment option. Low incidence, an absence of representative preclinical models and a lack of understanding of the tumour microenvironment all present challenges to drug development in this disease group. However, progress made in elucidating the mutational landscape of EP-PD-NEC and the observations made in several clinical trials are paving the way towards improving outcomes for these patients. The optimisation and strategic delivery of chemotherapeutic interventions according to tumour characteristics and the utilisation of targeted and immune therapies in clinical studies have yielded mixed results. Targeted therapies that complement specific genetic aberrations are under investigation, including AURKA inhibitors in those with MYCN amplifications, BRAF inhibitors in those with BRAFV600E mutations and EGFR suppression, and Ataxia Telangiectasia and Rad3-related inhibitors in patients with ATM mutations. Immune checkpoint inhibitors (ICIs) have conferred promising results in several clinical trials, particularly with dual ICIs and in combination with targeted therapy or chemotherapy. However, further prospective investigations are required to elucidate the impact of programmed cell death ligand 1 expression, tumour mutational burden and microsatellite instability on response. This review aims to explore the most recent developments in the treatment of EP-PD-NEC and contribute towards the requirement for clinical guidance founded on prospective evidence.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Immunotherapy in Gastroenteropancreatic Neuroendocrine Neoplasia

The worldwide prevalence and incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) and of NENs, in general, have been increasing recently. While valuing the considerable progress made in the treatment strategies for GEP-NEN in recent years, patients with advanced, metastasized disease still have a poor prognosis, which calls for urgent novel therapies. The immune system plays a dual role: both host-protecting and "tumor-promoting." Hence, immunotherapy is potentially a powerful weapon to help NEN patients. However, although recent successes with checkpoint inhibitors have shown that enhancing antitumor immunity can be effective, the dynamic nature of the immunosuppressive tumor microenvironment presents significant hurdles to the broader application of these therapies. Studies led to their approval in NEN of the lung and Merkel cell carcinoma, whereas results in other settings have not been so encouraging. Oncolytic viruses can selectively infect and destroy cancer cells, acting as an in situ cancer vaccine. Moreover, they can remodel the tumor microenvironment toward a T cell-inflamed phenotype. Oncolytic virotherapy has been proposed as an ablative and immunostimulatory treatment strategy for solid tumors that are resistant to checkpoint inhibitors alone. Future efforts should focus on finding the best way to include immunotherapy in the GEP-NEN treatment scenario. In this context, this study aims at providing a comprehensive generalized review of the immune checkpoint blockade and the oncolytic virotherapy use in GEP-NENs that might improve GEP-NEN treatment strategies.

Immune Checkpoint Inhibitor Therapy in Neuroendocrine Tumors

Neuroendocrine tumors (NETs) occur in various regions of the body and present with complex clinical and biochemical phenotypes. The molecular underpinnings that give rise to such varied manifestations have not been completely deciphered. The management of neuroendocrine tumors (NETs) involves surgery, locoregional therapy, and/or systemic therapy. Several forms of systemic therapy, including platinum-based chemotherapy, temozolomide/capecitabine, tyrosine kinase inhibitors, mTOR inhibitors, and peptide receptor radionuclide therapy have been extensively studied and implemented in the treatment of NETs. However, the potential of immune checkpoint inhibitor (ICI) therapy as an option in the management of NETs has only recently garnered attention. Till date, it is not clear whether ICI therapy holds any distinctive advantage in terms of efficacy or safety when compared to other available systemic therapies for NETs. Identifying the characteristics of NETs that would make them (better) respond to ICIs has been challenging. This review provides a summary of the current evidence on the value of ICI therapy in the management of ICIs and discusses the potential areas for future research.

Evaluation of PD-L1 expression in a large set of gastroenteropancreatic neuroendocrine tumours and correlation with clinicopathological data

BACKGROUND

Targeting programmed death protein 1 (PD-1) or its ligand PD-L1 is a promising therapeutic approach for many types of cancer in which PD-L1 is overexpressed. However, data on PD-L1 expression levels in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are limited and contradictory.

METHODS

We evaluated PD-L1 expression in 457 archived, formalin-fixed, paraffin-embedded GEP-NEN samples from 175 patients by immunohistochemistry using the highly sensitive monoclonal anti-PD-L1 antibody 73-10. The immunostaining was semiquantitatively evaluated using a 12-point immunoreactivity score (IRS) taking both PD-L1-positive tumour cells and immune cells into account. Tumour samples with an IRS ≥ 3 were considered PD-L1-positive. Results were correlated with clinicopathological data and with the expression of several typical markers and receptors for neuroendocrine tumours.

RESULTS

Of the GEP-NEN samples, 73% were PD-L1-positive. The median IRS value across all samples was 4.0, corresponding to low expression. PD-L1 immunostaining was predominantly localised at the plasma membrane of the tumour cells. Positive correlations were observed between PD-L1 expression and tumour grading or Ki-67 index, between PD-L1 expression and the expression of chromogranin A, and between PD-L1 expression and the expression of each of the five somatostatin receptors. PD-L1 expression was lower in tumours with lymph node metastases at diagnosis than in those without regional metastasis and lower in high-stage than in earlier-stage tumours. No association was noted between PD-L1 expression and patient survival.

CONCLUSIONS

PD-L1 expression is common in GEP-NENs and increases with malignancy. Therefore, especially in high-grade GEP-NENs, targeting the PD-1/PD-L1 axis could be a promising additional therapeutic strategy.

Potential new applications of immunotherapy for neuroendocrine neoplasms: immune landscape, current status and future perspectives

Neuroendocrine neoplasms (NENs) are a highly heterogeneous class of tumors arising from neuroendocrine cells and peptidergic neurons. After failure of first-line treatment, patients have poor prognosis and limited treatment options. Immune checkpoint inhibitors (ICIs) may be a powerful means of increasing therapeutic efficacy for such patients, but ICIs alone have low response rates and short disease control durations in most NENs and may be effective for only a portion of the population. ICIs combined with other immunotherapies, targeted therapies, or cytotoxic drugs have achieved some efficacy in patients with NENs and are worthy of further exploration to assess their benefits to the population. In addition, accumulating experimental and clinical evidence supports that the interaction between neuroendocrine and immune systems is essential to maintain homeostasis, and assessment of this broad neuroendocrine-immune correlation is essential for NEN treatment. In this review, we summarize the immune microenvironment characteristics, advances in immunotherapy, predictive biomarkers of ICI efficacy for NENs, and the effects of common endocrine hormones on the immune system, highlighting possible new application areas for this promising treatment in neglected NENs.

The Landscape and Clinical Application of the Tumor Microenvironment in Gastroenteropancreatic Neuroendocrine Neoplasms

Simple Summary

The tumor microenvironment (TME) plays a role in promoting tumor progression. Elucidating the relationship between the TME and tumor cells will benefit current therapies. Therefore, this review summarizes the most recent relationship between the TME and tumor characteristics, discusses the differences in the TME at various sites along the digestive tract, and compares the TMEs of neuroendocrine tumors and neuroendocrine carcinomas. Microbial ecological changes in the TME were reviewed. The clinical application of the TME was summarized from bench to bedside. The TME can be used as a tumor drug target for diagnostic value, prognosis prediction, and efficacy evaluation, further revealing the potential of immune checkpoints combined with antiangiogenic drugs. The clinical application prospects of adoptive cell therapy and oncolytic viruses were described. The potential therapeutic approaches and strategies for gastrointestinal neuroendocrine neoplasms are considered.

Abstract

Gastroenteropancreatic neuroendocrine neoplasms feature high heterogeneity. Neuroendocrine tumor cells are closely associated with the tumor microenvironment. Tumor-infiltrating immune cells are mutually educated by each other and by tumor cells. Immune cells have dual protumorigenic and antitumorigenic effects. The immune environment is conducive to the invasion and metastasis of the tumor; in turn, tumor cells can change the immune environment. These cells also form cytokines, immune checkpoint systems, and tertiary lymphoid structures to participate in the process of mutual adaptation. Additionally, the fibroblasts, vascular structure, and microbiota exhibit interactions with tumor cells. From bench to bedside, clinical practice related to the tumor microenvironment is also regarded as promising. Targeting immune components and angiogenic regulatory molecules has been shown to be effective. The clinical efficacy of immune checkpoint inhibitors, adoptive cell therapy, and oncolytic viruses remains to be further discussed in clinical trials. Moreover, combination therapy is feasible for advanced high-grade tumors. The regulation of the tumor microenvironment based on multiple omics results can suggest innovative therapeutic strategies to prevent tumors from succeeding in immune escape and to support antitumoral effects.

Exploring Real World Outcomes with Nivolumab Plus Ipilimumab in Patients with Metastatic Extra-Pulmonary Neuroendocrine Carcinoma (EP-NEC)

Simple Summary

Extrapulmonary neuroendocrine carcinomas (EP-NEC) are a group of tumors which are often metastatic and characterized by poor outcomes. Platinum-etoposide chemotherapy is the current front-line therapy for metastatic EP-NEC, and has been adapted from small cell lung cancer. There are limited treatment options for patients with platinum-resistant EP-NEC, with no current established second-line standard of care. Recently, there has been mixed evidence for the role of immunotherapy in EP-NEC, with limited existing prospective data. In this multicenter retrospective analysis, we compared outcomes between patients with refractory EP-NEC who received single, dual immune check point inhibitors (ICPIs) and cytotoxic chemotherapy in the second-line setting. This real world experience suggests that utilizing ipilimumab and nivolumab in patients with second-line pretreated EP-NEC may be more effective than other existing treatment options.

Abstract

Background: Dual utilization of the immune checkpoint inhibitors (ICPIs) nivolumab plus ipilimumab has demonstrated clinical promise in the treatment of patients with refractory high-grade neuroendocrine neo-plasms (NENs) in phase II clinical trials (DART SWOG 1609 and CA209), while single agent ICPIs have largely been ineffective for these types of tumors. While both trials demonstrated promising results in high grade NENs, there was no adequate description of the association between tumor differentiation (high-grade well-differentiated neuroendocrine tumor vs poorly-differentiated extra-pulmonary neuroendocrine carcinoma (EP-NEC) and ICPI outcomes in the DART SWOG 1609 trial. Our study reports on the effectiveness and toxicity profile of dual ICPIs in a real world second-line EP-NEC patient population. Methods: Data on metastatic EP-NEC patients, treated with either ICPIs (single and dual ICPIs) or chemo-therapy in the second-line setting, were retrieved from databases of three comprehensive cancer centers. Associations between treatment characteristics and outcomes, including progression-free survival (PFS) and overall survival (OS), were evaluated. Results: From 2007 to 2020, we identified 70 patients with metastatic EP-NEC (predominantly of gastro-enteropancreatic origin), of whom 42 patients (23 males, 19 females, median age 62 years old) were eligible for the final analysis. All patients were refractory to platinum etoposide doublet chemotherapy in the first-line setting. The median PFS for patients who received dual ICPIs (11 patients), single agent ICPI (8 patients), and cytotoxic chemotherapy (23 patients) was 258 days, 56.5 days, and 47 days, respectively (p = 0.0001). Median overall survival (OS) for those groups was not reached (NR), 18.7 months, and 10.5 months, respectively (p = 0.004). There were no significant differences in treatment outcomes in patients according to tumor mismatch repair (MMR) or tumor mutational burden (TMB) status. Grade 3–4 adverse events (AEs) were reported in 11.1% of the patients who received dual ICPIs; however, none of these AEs led to permanent treatment discontinuation. Conclusions: In the second-line setting, patients with EP-NECs treated with dual ICPIs (nivolumab plus ipilimumab) experienced improved PFS and OS compared to patients treated with single agent ICPI or cytotoxic chemotherapy. These results echo some of the current evidence for ICPIs in grade 3 NENs and need to be validated in future prospective studies.

Primary Neuroendocrine Tumor of the Breast: Current Understanding and Future Perspectives

Primary neuroendocrine carcinoma of the breast (NECB) is characterized with heterogeneity, rarity, and poor differentiation, which is probably an underestimated subtype of breast cancer, including small cell NECs and large cell NECs. The diagnostic criteria for NECB have been constantly updated as the disease changes and the understanding increases. According to the latest WHO Classification, primary neuroendocrine neoplasm (NEN) of the breast consists of well-differentiated neuroendocrine tumors (NET), extremely aggressive neuroendocrine carcinomas (NEC) as well as invasive breast cancers of no special type (IBCs-NST) with neuroendocrine differentiation. The accurate diagnosis of NECB remains a challenge for its low incidence, which needs multi-disciplinary methods. For the rarity of the disease, there is a lack of large samples and prospective clinical research. For these invasive tumors, there are no standardized therapeutic guidelines or norms, and the treatment often refers to nonspecific breast cancer. In addition, the prognosis of such patients remains unknown. In 2003, the World Health Organization (WHO) listed NECB as an independent entity for the first time, while few features of NECB were clarified. In this review, it presents the WHO Classification, clinicopathologic characteristics, diagnosis, treatment, and prognosis of these patients. In addition, it summarizes the latest studies on molecular features of NECB, aiming to provide new therapeutic perspectives for the disease.

New insights in diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are rare epithelial neoplasms derived from pluripotent endocrine cells along the gastrointestinal tract and pancreas. GEP-NENs are classified into well-differentiated neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas. Despite overlapping morphological features, GEP-NENs vary in molecular biology, epigenetic, clinical behavior, treatment response, and prognosis features and remain an unmet clinical challenge. In this review, we introduce recent updates on the histopathologic classification, including the tumor grading and staging system, molecular genetics, and systemic evaluation of the diagnosis and treatment of GEP-NENs at different anatomic sites, together with some insights into the diagnosis of challenging and unusual cases. We also discuss the application of novel therapeutic approaches for GEP-NENs, including peptide receptor radionuclide therapy, targeted therapy, and immunotherapy with immune checkpoint inhibitors. These findings will help improve patient care with precise diagnosis and individualized treatment of patients with GEP-NENs.

Oncolytic vaccinia virus injected intravenously sensitizes pancreatic neuroendocrine tumors and metastases to immune checkpoint blockade

This study determined the influence of intravenous (i.v.) oncolytic vaccinia virus mpJX-594 (mpJX) on antitumor activity of anti-programmed death receptor-1 antibody (aPD1) in functional and metastatic pancreatic neuroendocrine tumors (PanNETs). One i.v. dose of mpJX, engineered for mice with the same plasmid design as clinical virus Pexa-Vec, was administered alone or with repeated dosing of aPD1 (mpJX+aPD1) to two contrasting genetic models of PanNET: one developing benign insulin-secreting tumors (RIP1-Tag2;C57BL/6J mice) and the other developing liver metastases (RIP1-Tag2;AB6F1 mice). Experiments revealed that aPD1 had synergistic actions with mpJX on CD8⁺ T cell and natural killer (NK) cell influx, apoptosis, and suppression of proliferation in PanNETs. After mpJX+aPD1, the 53-fold increase in apoptosis (5 days) and 85% reduction in proliferation (20 days) exceeded the sum of mpJX and aPD1 given separately. mpJX+aPD1 also stabilized blood insulin and glucose in mice with functional PanNETs, regressed liver metastases in mice with aggressive PanNETs, and prolonged survival of both. The findings revealed that mpJX+aPD1 converted “cold” PanNETs into immunogenic tumors with widespread cytotoxic T cell influx, tumor cell killing, and suppression of proliferation. Reduction of tumor insulin secretion from functional PanNETs prolonged survival, and anti-metastatic actions on aggressive PanNETs reduced the metastatic burden to less than before treatment. The findings support the efficacy of the vaccinia virus with aPD1 for functional and metastatic PanNETs.

Therapeutic strategies for gastroenteropancreatic neuroendocrine neoplasms: State-of-the-art and future perspectives

Although gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have always been considered rare tumors, their incidence has risen over the past few decades. They represent a highly heterogeneous group of neoplasms with several prognostic factors, including disease stage, proliferative index (Ki67), and tumor differentiation. Most of these neoplasms express somatostatin receptors on the cell surface, a feature that has important implications in terms of prognosis, diagnosis, and therapy. Although International Guidelines propose algorithms aimed at guiding therapeutic strategies, GEP-NEN patients are still very different from one another, and the need for personalized treatment continues to increase. Radical surgery is always the best option when feasible; however, up to 80% of cases are metastatic upon diagnosis. Regarding medical treatments, as GEP-NENs are characterized by relatively long overall survival, multiple therapy lines are adopted during the lifetime of these patients, but the optimum sequence to be followed has never been clearly defined. Furthermore, although new molecular markers aimed at predicting the response to therapy, as well as prognostic scores, are currently being studied, their application is still far from being part of daily clinical practice. As they represent a complex disease, with therapeutic protocols that are not completely standardized, GEP-NENs require a multidisciplinary approach. This review will provide an overview of the available therapeutic options for GEP-NENs and attempts to clarify the possible approaches for the management of these patients and to discuss future perspectives in this field.

Efficacy of Immune Checkpoint Inhibitors against Advanced or Metastatic Neuroendocrine Neoplasms: A Systematic Review and Meta-Analysis

We performed a systematic review and meta-analysis of the treatment efficacy of immune checkpoint inhibitors (ICIs) in advanced/metastatic neuroendocrine neoplasms (NENs). MEDLINE and EMBASE were searched to identify studies that provide data on treatment response and/or survival outcomes of advanced/metastatic NEN patients treated with ICIs. The overall response rate (ORR) was pooled using a random-effects model. Meta-regression was performed to explore factors influencing the ORR. Individual patient data (IPD) meta-analysis of survival was performed using stratified Cox regression. Ten studies (464 patients) were included. The overall pooled ORR was 15.5% (95% confidence interval (CI), 9.5-24.3%), and it varied according to the primary site (thoracic, 24.7%; gastro-entero-pancreatic, 9.5%), tumor differentiation (poorly differentiated, 22.7%; well-differentiated, 10.4%), and drug regimen (combination, 25.3%; monotherapy, 10.1%). All these variables significantly influenced the ORR. Tumor differentiation was associated with both overall survival and progression-free survival (hazard ratio of poorly differentiated tumors, 4.2 (95% CI, 2.0-8.7) and 2.6 (95% CI, 1.6-4.4), respectively). Thus, the treatment efficacy of ICIs for advanced/metastatic NENs varied according to primary site, tumor differentiation, and drug regimen. Poorly differentiated NENs showed a better ORR than well-differentiated NENs but had a negative impact on survival.