High-grade Neuroendocrine Tumors Research Articles

Combined deletion of MEN1, ATRX and PTEN triggers development of high-grade pancreatic neuroendocrine tumors in mice

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of tumors that exhibit an unpredictable and broad spectrum of clinical presentations and biological aggressiveness. Surgical resection is still the only curative therapeutic option for localized PanNET, but the majority of patients are diagnosed at an advanced and metastatic stage with limited therapeutic options. Key factors limiting the development of new therapeutics are the extensive heterogeneity of PanNETs and the lack of appropriate clinically relevant models. In that context, genomic sequencing of human PanNETs revealed recurrent mutations and structural alterations in several tumor suppressors. Here, we demonstrated that combined loss of MEN1, ATRX, and PTEN, tumor suppressors commonly mutated in human PanNETs, triggers the development of high-grade pancreatic neuroendocrine tumors in mice. Histopathological evaluation and gene expression analyses of the developed tumors confirm the presence of PanNET hallmarks and significant overlap in gene expression patterns found in human disease. Thus, we postulate that the presented novel genetically defined mouse model is the first clinically relevant immunocompetent high-grade PanNET mouse model.

Treatment and long term safety outcomes of Peptide Receptor Radionuclide Therapy for metastatic neuroendocrine tumours: an Asian experience.

Peptide-receptor radionuclide therapy (PRRT) is a targeted molecular therapy used to treat neuroendocrine tumours (NET). It has been shown to be effective and well-tolerated in patients with metastatic neuroendocrine tumours in several centres in United States (US), Europe and Australia. Tolerability and efficacy data emerging from Asian centres remain few. Epidemiological evidence suggests that there are differences in neuroendocrine neoplasms between the population groups. We aim to describe the treatment and safety outcomes of PRRT in the Asian population. Methods One hundred and seven (107) patients with metastatic neuroendocrine tumour who had undergone PRRT treatment from January 2012 to March 2019 were included in this retrospective study. The response rates using RECIST1.1 and qualitative analysis were examined. The overall and progression free survival curves were also evaluated. Results The median progression free survival was 49 months. Response assessment after completion of treatment showed that 33(37.9%) of 87 patients had partial or complete response. Subgroup analysis comparing high- and low-grade NET showed that there was a significant difference in the time to progression curves. Comparison of the number of cycles and progression free and overall survival also showed a significant difference. Ten patients (9%) had grade 3 or more haematological toxicities. Four patients (4%) had grade 3/4 hepatobiliary toxicities, although the presence of extensive liver metastases was a confounding factor. None of the patients had grade 3/4 acute kidney injury. Conclusion Our results show that PRRT is safe and effective in the treatment of metastatic neuroendocrine tumour in the Asian population. There was a significant difference in the progression free survival curves between low-grade and high-grade NET, and in the progression free and overall survival comparing the number of cycles received.

Abstract 3146: HRA00130-C004, a novel anti-DLL3 ADC with bystander effect, high DAR and favorable safety profiles

Abstract Small Cell Lung Cancer (SCLC) is a highly aggressive neuroendocrine tumor, accounting for ~15% of all new lung cancer cases1. It is estimated that there are 250,000 new SCLC cases and at least 200,000 deaths globally each year2. SCLC exhibits high recurrence after first-line treatment, poor response to subsequent therapies, and rare survival3. Lacking of recommended treatments for prolonging survival remains a problem over decades4. DLL3 is an inhibitory ligand of the Notch receptor. It binds to its Notch receptor through a cis-interaction, thus, mediates inhibition of Notch pathway to facilitate neuroendocrine tumorigenesis5. DLL3 is highly upregulated and aberrantly expressed on the cell surface in SCLC and other high-grade neuroendocrine tumors with limited expression in normal tissues6.Here we presented a DLL3-directed ADC, HRA00130-C004, which features a differentiated topoisomerase I inhibitor payload DXh conjugated via a cleavable linker to a humanized IgG1 antibody. HRA00130-C004 strongly inhibited the proliferation of cell lines with different DLL3 expression. In the bystander killing assays, HRA00130-C004 was able to kill both DMS53 cells (DLL3 over-expressed) and U-2OS (DLL3-negative) cells when they are co-cultured. The in vivo treatment of HRA00130-C004 resulted in a dramatic and sustained inhibition of tumor growth in H1184 (DLL3 high) and DMS53 (DLL3 low) xenograft models. No obvious weight loss was observed during the experiment. Furthermore, HRA00130-C004 demonstrated a favorable PK profile and satisfactory molecular integrity in rats with 3mg/kg dosing and cynomolgus monkeys with 10 mg/kg dosing. The exposure of total antibody and intact ADC was consistent. Moreover, HRA00130-C004 was well tolerated in rats and cynomolgus monkeys with no related adverse findings, which indicated its favorable safety profiles. In summary, taking advantage of Hengrui’s DXh platform, HRA00130-C004 has demonstrated great potency and good safety profiles. These data support the future clinical development of HRA00130-C004. 1.CA Cancer J. Clin., 2018, 68, 7; 2.J. Natl. Compr. Cancer Netw. 2018, 16, 1171; 3.Mol. Ther. Oncolytics, 2021, 20, 470; 4.Journal of Cancer, 2022, 13, 2945; 5.Cellular Oncology, 2019, 42, 261; 6.Journal of Hematology and Oncology 2019, 12, 61; Citation Format: Qingqing Yao, Changding Xue, Zhibin Xu, Lingfeng You, Zhendong Xue, Yuchang Mao, Sophie Lin, Jun Feng, Zhe Zhang, Xin Ye, Min Hu, Feng He. HRA00130-C004, a novel anti-DLL3 ADC with bystander effect, high DAR and favorable safety profiles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3146.

Abstract 5953: DUSP6 is a novel target in neuroendocrine tumors

Abstract Background: Neuroendocrine tumors (NETs) are rare malignancies derived from enterochromaffin cells of the diffuse neuroendocrine system and most frequently observed in the gastrointestinal tract and bronchopulmonary system. Surgery is the major treatment for localized NETs. In high-grade NETs, treatment opportunities include chemotherapeutic drugs such as temozolomide (TEM), and capecitabine and small-molecule targeted therapies such as everolimus or sunitinib. Despite promising initial responses, most patients develop therapy resistance by unknown mechanisms. Therefore, there is a pressing need to apprehend the mechanisms of resistance to improve the therapeutic efficacy of the current treatments. Phosphatases are emerging and novel targets in human malignancies and their modulation yields significant anti-tumor activities. Dual specificity phosphatase 6 (DUSP6) is a MAPK phosphatase and mainly binds to and dephosphorylates extracellular signal-regulated kinase (ERK)1/2. DUSP6 expression is increased in several malignancies, correlating with distant metastases and a worse clinical outcome. Moreover, DUSP6 mediates resistance to certain chemotherapeutics and small molecular tyrosine kinase inhibitors and its blockade increases therapeutic sensitivity. The current study aimed to investigate the contribution of DUSP6 to therapy resistance in the NET models. Material and Methods: Using Western blot analysis, the expression of DUSP6 was measured in 8 clinical samples of small bowel neuroendocrine tumors, the NET cell lines BON-1, H69, IMR-32, QGP and H524 and two PDX models, 1452 (rectal neuroendocrine) and 913 (pancreatic neuroendocrine). The effects of DUSP6 depletion on cell viability were explored using a pharmacological inhibitor, BCI, and its siRNA-mediated knockdown. Moreover, BCI-mediated apoptotic cell death was measured by an annexin V/PI staining assay. Results: DUSP6 expression was positive in 5 out of 8 clinical samples, 4 NET cell lines and both the PDX models. BCI treatment induced an apoptotic response in the NET models and synergistically increased sensitivity to TMZ and cisplatin in 1452 cells., RNAi-mediated depletion of DUSP6 also increased sensitivity to sunitinib and triggered TMZ-induced apoptotic cell death in 1452 cells, which was associated with changes in (O6-Methylguanine-DNA-methyltransferase) MGMT expression. These findings suggest that DUSP6 is an important therapeutic target in neuroendocrine tumors and its blockade is a promising therapeutic approach to enhance the therapeutic index of current treatments. Citation Format: Majid Momeny, Vahid Khalaj, Solmaz AghaAmiri, Po Hien Ear, Servando Hernandez Vargas, Sukhen Ghosh, Ali Azhdarinia. DUSP6 is a novel target in neuroendocrine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5953.

Patient derived tumoroids of high grade neuroendocrine neoplasms for more personalized therapies

There are no therapeutic predictive biomarkers or representative preclinical models for high-grade gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN), a highly aggressive, fatal, and heterogeneous malignancy. We established patient-derived (PD) tumoroids from biobanked tissue samples of advanced high-grade GEP-NEN patients and applied this model for targeted rapid ex vivo pharmacotyping, next-generation sequencing, and perturbational profiling. We used tissue-matched PD tumoroids to profile individual patients, compared ex vivo drug response to patients’ clinical response to chemotherapy, and investigated treatment-induced adaptive stress responses.PD tumoroids recapitulated biological key features of high-grade GEP-NEN and mimicked clinical response to cisplatin and temozolomide ex vivo. When we investigated treatment-induced adaptive stress responses in PD tumoroids in silico, we discovered and functionally validated Lysine demethylase 5 A and interferon-beta, which act synergistically in combination with cisplatin. Since ex vivo drug response in PD tumoroids matched clinical patient responses to standard-of-care chemotherapeutics for GEP-NEN, our rapid and functional precision oncology approach could expand personalized therapeutic options for patients with advanced high-grade GEP-NEN.

Differentiating high-grade neuroendocrine neoplasms.

Differentiating high-grade neuroendocrine neoplasms.

Alternative schedule of temozolomide/capecitabine in neuroendocrine neoplasms.

The chemotherapy regimen capecitabine/temozolomide (CAPTEM) is routinely used in neuroendocrine tumors (NET), with antitumor activity particularly demonstrated in pancreatic or high-grade neuroendocrine neoplasms (NEN). However, different dosing regimens are used, and the optimal schedule remains to be defined. This single-center retrospective analysis assessed the efficacy and safety of CAPTEM in patients with NEN using a schedule starting both compounds simultaneously (temozolomide on days 1-5 and capecitabine on days 1-14 of a 28-day cycle) rather than sequentially. The primary parameters of interest were response rates, progression-free survival (PFS), and toxicities following this treatment regimen, hereinafter referred to as TEMCAP. The study population comprised 40 patients, half of whom (n = 20) had pancreatic NEN, and 9 patients (22.5%) had pulmonary or thymic NETs. The most common histology was NET G3 (n = 15, 37.5%), and 8 patients (20.0%) had a neuroendocrine carcinoma (NEC). Most patients (77.5%) had at least one prior systemic therapy, and 16 patients (40.0%) prior chemotherapy. The median number of TEMCAP cycles was 6 (range 1-16). Median PFS for the highly heterogeneous population was 13.3 months, while the median overall survival was 31.9 months. In total, 14/36 patients (38.9%) exhibited a partial response, and the disease control rate was 75.0%. The safety profile of TEMCAP (at a below-target mean temozolomide dose of 118.85 mg/m2) in our cohort was remarkably good with no toxicities of grade 3 or 4. Taken together, the results of this analysis further support the use of temozolomide/capecitabine in NEN and prompt further assessment of our modified TEMCAP schedule.

Novel ensemble feature selection techniques applied to high-grade gastroenteropancreatic neuroendocrine neoplasms for the prediction of survival

Background and ObjectiveDetermining the most informative features for predicting the overall survival of patients diagnosed with high-grade gastroenteropancreatic neuroendocrine neoplasms is crucial to improve individual treatment plans for patients, as well as the biological understanding of the disease. The main objective of this study is to evaluate the use of modern ensemble feature selection techniques for this purpose with respect to (a) quantitative performance measures such as predictive performance, (b) clinical interpretability, and (c) the effect of integrating prior expert knowledge. MethodsThe Repeated Elastic Net Technique for Feature Selection (RENT) and the User-Guided Bayesian Framework for Feature Selection (UBayFS) are recently developed ensemble feature selectors investigated in this work. Both allow the user to identify informative features in datasets with low sample sizes and focus on model interpretability. While RENT is purely data-driven, UBayFS can integrate expert knowledge a priori in the feature selection process. In this work, we compare both feature selectors on a dataset comprising 63 patients and 110 features from multiple sources, including baseline patient characteristics, baseline blood values, tumor histology, imaging, and treatment information. ResultsOur experiments involve data-driven and expert-driven setups, as well as combinations of both. In a five-fold cross-validated experiment without expert knowledge, our results demonstrate that both feature selectors allow accurate predictions: A reduction from 110 to approximately 20 features (around 82%) delivers near-optimal predictive performances with minor variations according to the choice of the feature selector, the predictive model, and the fold. Thereafter, we use findings from clinical literature as a source of expert knowledge. In addition, expert knowledge has a stabilizing effect on the feature set (an increase in stability of approximately 40%), while the impact on predictive performance is limited. ConclusionsThe features WHO Performance Status, Albumin, Platelets, Ki-67, Tumor Morphology, Total MTV, Total TLG, and SUVmax are the most stable and predictive features in our study. Overall, this study demonstrated the practical value of feature selection in medical applications not only to improve quantitative performance but also to deliver potentially new insights to experts.

Chemokine Receptor CXCR4 Radioligand Targeted Therapy Using 177Lutetium-pentixather for Pulmonary Neuroendocrine Cancers.

Intermediate to high-grade lung neuroendocrine tumors (NETs; i.e., atypical carcinoid tumors) and neuroendocrine carcinomas (NECs) are currently difficult to cure. These tumors were found to express the CXCR4 G-protein coupled receptor that can be targeted with radioligands. PCR and flow cytometric analysis of lung NET and NEC cell lines using an anti-CXCR4 antibody demonstrated that all cell lines tested expressed CXCR4. PET/CT imaging with 68Galium-pentixafor in mouse xenografts of NETs and NECs verified tumor targeting that was blocked by a CXCR4 agonist. Clonogenic survival analysis demonstrated a more than additive enhancement of killing when 1 μM auranofin (a thioredoxin reductase inhibitor) was used as a radiosensitizer in combination with 177Lu-pentixather (10 μCi). DMS273 small cell lung cancer xenografts in female nude mice treated with 25 μCi/g 177Lu-pentixather induced inhibition of tumor growth and resulted in an increase in overall survival without causing unacceptable normal tissue toxicities. Immunohistochemical staining of 95 retrospective human samples (containing 90 small cell lung carcinomas) demonstrated 84% CXCR4 positivity. In a multivariable analysis of this cohort that included age, gender, stage, primary site, SSTR2 status, and CXCR4 status, Cox regression models determined that only distant metastasis at presentation (P < 0.01) and a CXCR4 H-score >30 (P = 0.04) were significantly associated with reduced survival. Prospective clinical testing of patient tumors identified CXCR4-positivity in 76% of 21 NECs, 67% of 15 lung NETs (including 8 of 10 atypical carcinoids), and 0% of 25 non-lung NETs (including 5 NETS G3s). These data support the hypothesis that CXCR4-targeted theranostics can be utilized effectively for select NETs and NECs.

Targeting CXCR4 and Thioredoxin Reductase in High Grade Neuroendocrine Tumors & Neuroendocrine Carcinomas

Targeting CXCR4 and Thioredoxin Reductase in High Grade Neuroendocrine Tumors & Neuroendocrine Carcinomas

The molecular characteristics of high-grade gastroenteropancreatic neuroendocrine neoplasms

The molecular characteristics of high-grade gastroenteropancreatic neuroendocrine neoplasms

Phase II study of everolimus and temozolomide as first-line treatment in metastatic high-grade gastroenteropancreatic neuroendocrine neoplasms

BackgroundThe optimal treatment for metastatic high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms when Ki-67 ≤55% is unknown. A prospective multi-centre phase 2 study was performed to evaluate the efficacy and safety of everolimus and temozolomide as first-line treatment for these patients.MethodsPatients received everolimus 10 mg daily continuously and temozolomide 150 mg/m2 for 7 days every 2 weeks. Endpoints included response, survival, safety and quality of life (QoL). Histopathological re-evaluation according to the 2019 WHO classification was performed.ResultsFor 37 eligible patients, the primary endpoint with 65% disease control rate (DCR) at 6 months (m) was reached. The response rate was 30%, the median progression-free survival (PFS) 10.2 months and the median overall survival (OS) 26.4 months. Considering 26 NET G3 patients, 6 months DCR was 77% vs. 22% among nine NEC patients (p = 0.006). PFS was superior for NET G3 vs. NEC (12.6 months vs. 3.4 months, Log-rank-test: p = 0.133, Breslow-test: p < 0.001). OS was significantly better for NET G3 (31.4 months vs. 7.8 months, p = 0.003). Grade 3 and 4 toxicities were reported in 43% and 38%. QoL remained stable during treatment.ConclusionEverolimus and temozolomide may be a treatment option for selected GEP-NET G3 patients including careful monitoring. Toxicity did not compromise QoL.Clinical trial registrationClinicalTrials.gov (NTC02248012).

The maximal contrast-enhanced range of CT for differentiating the WHO pathological subtypes and risk subgroups of thymic epithelial tumors.

To explore the value of maximal contrast-enhanced (CEmax) range using contrast-enhanced CT (CECT) imaging in differentiating the pathological subtypes and risk subgroups of thymic epithelial tumors (TETs). The pre-treatment-CECT images of 319 TET patients from May 2012 to November 2021 were analyzed retrospectively. The CEmax was defined as the maximum difference between the CT value of the solid tumor on pre-contrast and contrast-enhanced images. The mean CEmax value was calculated at three different tumor levels. There was a significant difference in the CEmax among the eight main pathological subtypes [types A, AB, B1, B2, and B3 thymoma, thymic carcinoma (TC), low-grade neuroendocrine tumor (NET) and high-grade NET] (p < 0.001). Among the eight subtypes, the CEmax values of types A, AB, and low-risk NET were higher than those of the other subtypes (all p < 0.001), and there was no difference among types B1-B3 and high-risk NET (all p > 0.05). There was no difference for CEmax values between NET and TC (p = 0.491). For the risk subgroups, the CEmax of TC (including NET) was 35.35 ± 11.41 HU, which was lower than that of low-risk thymoma (A and AB) (57.73±21.24 HU) (P < 0.001) and was higher than that of high-risk thymoma (B1-B3) (27.37±8.27 HU) (P < 0.001). The CEmax cut-off values were 38.5 HU and 30.5 HU respectively (AUC: 0.829 and 0.712; accuracy, 72.4% and 67.7%). The tumor CEmax on CECT helps differentiate the pathological subtypes and risk subgroups of TETs. In this study, an improved simplified risk grouping method was proposed based on the traditional (2004 edition) simplified risk grouping method for TETs. If Type B1 thymoma is classified as high-risk, radiologists using this improved method may improve the accuracy in differentiating risk level of TETs compared with the traditional method.

Appendiceal Neuroendocrine Neoplasms: A Comprehensive Review.

Appendiceal neuroendocrine neoplasm (NEN) is the most common adult appendiceal malignant tumor, constituting 16% of gastrointestinal NENs. They are versatile tumors with varying morphology, immunohistochemistry, secretory properties, and cancer genomics. They are slow growing and clinically silent, to begin with, or present with features of nonspecific vague abdominal pain. Most acute presentations are attributed clinically to appendicitis, with most cases detected incidentally on pathology after an appendectomy. Approximately 40% of them present clinically with features of hormonal excess, which is likened to the functional secretory nature of their parent cell of origin. The symptoms of carcinoid syndrome render their presence clinically evident. However, slow growing and symptomatically silent in its initial stages, high-grade neuroendocrine tumors and neuroendocrine carcinomas of the appendix are aggressive and usually have hepatic and lymph node metastasis at presentation. This review article focuses on imaging characteristics, World Health Organization histopathological classification and grading, American Joint Committee on Cancer/Union or International Cancer Control, European Neuroendocrine Tumor Society staging, European Neuroendocrine Tumor Society standardized guidelines for reporting, data interpretation, early-stage management protocols, and advanced-stage appendiceal NENs. Guidelines are also set for the follow-up and reassessment. The role of targeted radiotherapy, chemotherapy, and high-dose somatostatin analogs in treating advanced disease are discussed, along with types of ablative therapies and liver transplantation for tumor recurrence. The search for newer location-specific biomarkers in NEN is also summarized. Regarding the varying aggressiveness of the tumor, there is a scope for research in the field, with plenty of data yet to be discovered.

Somatostatin receptor expression in Merkel cell carcinoma: correlation with clinical data

Background Merkel cell carcinoma (MCC) is a rare, high-grade neuroendocrine neoplasm (NEN) of the skin. Somatostatin receptors (SSTRs) are G protein-linked receptors that regulate cell proliferation and growth. SSTRs are expressed in many NENs; however, scant information is available on their expression in MCCs or their association with clinical parameters and patient outcomes. Material and methods This retrospective study was conducted at Helsinki University Hospital and the University of Helsinki. Using a tissue microarray, we investigated SSTR1-5 expression by immunohistochemistry in 99 MCC tissue samples. Samples were collected between 1983 and 2017 and coupled with the patients’ clinical data. Results SSTR2-SSTR5 were detected in 69%, 6%, 4%, and 1% of the tumours, respectively. However, SSTR1 expression was not observed. Cytoplasmic SSTR2 positivity was associated with metastatic disease at the time of diagnosis (p = 0.009), but it did not correlate with disease-specificity or overall survival. Conclusion SSTR2-5 expression was observed in MCCs. In particular, SSTR2 expression is clinically valid because it is associated with metastatic disease at the time of diagnosis and can thus serve as a prognostic marker. Moreover, SSTR2 overexpression provides a molecular basis for tumour imaging and treatment with somatostatin analogues.

Primary Small Cell Carcinoma of the Breast: When a Rare Tumour is Real

Background: Extra-pulmonary small-cell neoplasms are rare, and treatment planning is challenging for clinicians. The lack of guideline-based management undermines and isolates patients for whom these cancers are not just rare but also real. Small-cell breast cancer (SCBC) is a rare, aggressive disease that accounts for less than 1% of all invasive breast cancers. Here, we report a case of SCBC and discuss the complexities of case management. Case Presentation: A 46-year-old patient presented with a self-detected right breast lump. Mammogram and ultrasound examination showed a 69x47mm dense lesion in the upper outer aspect of the right breast and a 17mm pathologic node in the inferior right axilla. The triple assessment demonstrated a localised high-grade malignant neuroendocrine neoplasm. Management extrapolated from small cell lung cancer management and case reports, consisted of chemotherapy with carboplatin, and etoposide introduced with concurrent radiotherapy, followed by mastectomy with axillary lymph node dissection. A complete pathological response was obtained. Six months following her surgery, metastatic disease in the brain, chest wall, lymph nodes, and lungs developed. Rechallenge with carboplatin and etoposide led to a brief response, and subsequent immunotherapy was ineffective. Conclusion: This case report highlights the challenges of rare tumour management. Establishing registries for these and other rare tumors would facilitate care, reduce patient uncertainty and assist in founding protocol-based care.

Germline pathogenic variants in patients with high-grade gastroenteropancreatic neuroendocrine neoplasms.

High-grade gastroenteropancreatic (HG-GEP) neuroendocrine neoplasms (NENs) are highly aggressive cancers. The molecular etiology of these tumors remains unclear, and the prevalence of pathogenic germline variants in patients with HG-GEP NENs is unknown. We assessed sequencing data of 360 cancer genes in normal tissue from 240 patients with HG-GEP NENs; 198 patients with neuroendocrine carcinomas (NECs) and 42 with grade 3 neuroendocrine tumors (NET G3). Applying strict criteria, we identified pathogenic germline variants and compared the frequency with previously reported data from 33 different cancer types. We found a recurrent MYOC variant in three patients and a recurrent MUTYH variant in two patients, indicating that these genes may be important underlying risk factors for HG-GEP NENs when mutated. Further, germline variants were found in canonical tumor-suppressor genes, such as TP53, RB1, BRIP1 and BAP1. Overall, we found that 4.5% of patients with NEC and 9.5% of patients with NET G3 carry germline pathogenic or highly likely pathogenic variants. Applying identical criteria for variant classification in silico to mined data from 33 other cancer types, the median percentage of patients carrying pathogenic or highly likely pathogenic variants was 3.4% (range: 0-17%). The patients with NEC and pathogenic germline variants had a median overall survival of 9 months, similar to what is generally expected for metastatic GEP NECs. A patient with NET G3 and pathogenic MUTYH variant had much shorter overall survival than expected. The fraction of HG-GEP NENs with germline pathogenic variants is relatively high, but still <10%, meaning that that germline mutations cannot be the major underlying cause of HG-GEP NENs.

De Novo and Histologically Transformed Small-Cell Lung Cancer Is Sensitive to Lurbinectedin Treatment Through the Modulation of EMT and NOTCH Signaling Pathways.

Small-cell lung cancer (SCLC) is a high-grade neuroendocrine tumor with dismal prognosis and limited treatment options. Lurbinectedin, conditionally approved as a second-line treatment for metastatic SCLC, drives clinical responses in about 35% of patients, and the overall survival (OS) of those who benefit from it remains very low (∼9.3 months). This finding highlights the need to develop improved mechanistic insight and predictive biomarkers of response. We used human and patient-derived xenograft (PDX)-derived SCLC cell lines to evaluate the effect of lurbinectedin in vitro. We also demonstrate the antitumor effect of lurbinectedin in multiple de novo and transformed SCLC PDX models. Changes in gene and protein expression pre- and post-lurbinectedin treatment was assessed by RNA sequencing and Western blot analysis. Lurbinectedin markedly reduced cell viability in the majority of SCLC models with the best response on POU2F3-driven SCLC cells. We further demonstrate that lurbinectedin, either as a single agent or in combination with osimertinib, causes an appreciable antitumor response in multiple models of EGFR-mutant lung adenocarcinoma with histologic transformation to SCLC. Transcriptomic analysis identified induction of apoptosis, repression of epithelial-mesenchymal transition, modulation of PI3K/AKT, NOTCH signaling associated with lurbinectedin response in de novo, and transformed SCLC models. Our study provides a mechanistic insight into lurbinectedin response in SCLC and the first demonstration that lurbinectedin is a potential therapeutic target after SCLC transformation.

NET G3 vs NEC: p53 and Rb1 Immunolabeling in High-grade Gastrointestinal Neuroendocrine Neoplasms - Is It Enough for the Differential Diagnosis?

High-grade gastrointestinal neuroendocrine neoplasms (GI-NENs) are divided into well-differentiated G3 neuroendocrine tumors (NETs G3) and neuroendocrine carcinomas (NECs), having identical cut-offs of proliferation, but different biomolecular origins. This translates in distinct treatment choices. Our aim was to establish if p53/Rb1 immunohistochemical status in GI-NENs with Ki67 index >20% can predict the histopathological diagnosis. p53/Rb1 immunolabelling was performed on 42 cases of high-grade GI-NENs, diagnosed as NET G3, NEC and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) with NEC component. Immunolabeled slides were digitally scanned, with automatic quantification of p53 and Rb1, blind to the diagnosis. The p53 positive percentage was stratified; two cut-offs were selected, naming the intervals as N (null, <1%), T (tumor, 1%-20%) and C (carcinoma, >20%). The Rb1 expression loss in >90% of neoplastic cells was considered mutational. NETs G3 mainly showed the T status (14/16, 87.5%), followed by N (1/16, 6.25%) and C (1/16, 6.25%); NECs and NEC components in MiNENs predominantly expressed the C status (19/26, 73.08%), followed by N (5/26, 19.23%) and T (2/26, 7.69%) (p<0.001, χ 2 =27.017). NET G3s showed positive expression for Rb1; 73.08% of NECs expressed negative Rb1 (p<0.001, χ 2 =21.351). NECs and NEC components in MiNENs showed Rb1 mutational status in 13 C cases (13/19, 68.42%), 4 N cases (4/5, 80%) and in both the T cases (p=0.002, χ 2 =11.187). Our results highlight the correlations between the p53/Rb1 immunostainings and the histopathological diagnosis of high-grade GI-NENs. NECs and NEC components in MiNENs showed a p53 mutational status (0% or 21-100%) and predominantly negative Rb1 expression. NETs G3 showed a p53 wild-type status (1-20%) and retained Rb1 expression. These findings suggest that the differential diagnosis of high-grade GI-NENs may benefit from p53/Rb1 immunohistochemical tests in everyday practice.

ATP6AP2 is robustly expressed in pancreatic β cells and neuroendocrine tumors, and plays a role in maintaining cellular viability

ATP6AP2, also known as (pro)renin receptor, has been shown to be expressed in several tissues including pancreatic β cells. Whereas ATP6AP2 plays an important role in regulating insulin secretion in mouse pancreatic β cells, the expression profiles and roles of ATP6AP2 in human pancreatic endocrine cells and neuroendocrine tumor cells remain unclear. Here in this study, we investigated the expression profiles of ATP6AP2 in pancreatic endocrine cells, and found that ATP6AP2 is robustly expressed in pancreatic insulinoma cells as well as in normal β cells. Although ATP6AP2 was also expressed in low-grade neuroendocrine tumors, it was not or faintly detected in intermediate- and high-grade neuroendocrine tumors. Knockdown experiments of the Atp6ap2 gene in rat insulinoma-derived INS-1 cells demonstrated decreased cell viability accompanied by a significant increase in apoptotic cells. Taken together, these findings suggest that ATP6AP2 plays a role in maintaining cellular homeostasis in insulinoma cells, which could lead to possible therapeutic approaches for endocrine tumors.