SEARCH · PubMed Health

Results for “neuroendocrine”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2026

Origin and evolution of colorectal mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN).

Colorectal neuroendocrine carcinoma (NEC) is a rare and aggressive cancer and in a subset of patients associated with an adenocarcinoma (AC) component. When both components exceed 30% of the tumour, it is classified as mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN), although there is an ongoing debate about whether any presence of two distinct components should be sufficient for a MiNEN diagnosis. This study aimed to investigate the origin and subsequent genetic changes of these two components. Ten colorectal cases suitable for sampling of an AC and a poorly differentiated NEC component were identified from the NORDIC NEC 2 study and sequenced across a 360-cancer gene panel. Mock phylogenetic trees were constructed from the molecular profiles of each sample within a patient. All ten cases revealed a common trunk of shared somatic mutations, including well-known colorectal cancer driver mutations such as BRAF, KRAS, APC, and TP53. In all cases, a single branching point separated the AC and NEC components. Private AC and NEC mutations generally had low variant allele frequencies, indicating that most AC and NEC cells were genetically similar. NEC, when compared with AC samples, demonstrated a higher frequency of private mutations (P = 0.009), indicating a higher mutation rate and greater ploidy (P = 0.012), suggesting an association between genomic duplication and AC-to-NEC transition. Shared mutations indicate a common clonal origin, underscoring the role of established colorectal driver mutations in the early development of these tumours, while the mechanisms underlying NEC differentiation remain poorly understood and may involve non-genetic factors.

Humans↗

PubMed2026

Immunological Features of Neuroendocrine Neoplasms and Adrenal Tumors.

Neuroendocrine neoplasms, which occur throughout the human body, as well as adrenocortical carcinoma and pheochromocytoma, which originate in the adrenal gland, are primarily classified as rare malignancies. Immunotherapy, including immune checkpoint inhibitors (ICIs), is generally not incorporated into the standard care protocols for these tumors. The clinical efficacy of ICIs in these tumors has been modest. This may be due to the biological heterogeneity of these tumors. The tumor immune microenvironment profiles are heterogeneous among the molecular subtypes of pheochromocytoma/paraganglioma, suggesting a potential benefit observed in selected subgroups. Poorly differentiated neuroendocrine carcinoma (NEC) exhibits spontaneous activation of adaptive immunity, unlike well-differentiated neuroendocrine tumors. A delta-like ligand 3-directed T-cell-engaging bispecific antibody, tarlatamab, has recently demonstrated prolonged survival in small cell lung cancer, and investigations into its use in extrapulmonary NEC are underway. This review examines the immunological features of representative neuroendocrine and adrenal tumors (neuroendocrine tumor, neuroendocrine carcinoma, adrenocortical carcinoma, and pheochromocytoma/paraganglioma). In the future, elucidating the relationship between specific molecular subtypes and immunophenotypes may facilitate the development of personalized therapies and guide clinical investigations in promising patient subpopulations.

Humans↗

PubMed2025

Clinicopathologic and Molecular Analysis of Colorectal Carcinomas With Spectrum of Neuroendocrine Carcinoma Components.

The genetics of colorectal carcinoma (CRC) with neuroendocrine differentiation remain poorly understood; recent studies focusing on pure neuroendocrine carcinomas (NECs) demonstrated mutation profiles closely resembling colorectal adenocarcinomas (ACAs) with more frequent BRAF mutations and Rb/p16 pathway dysregulation. However, pathogenesis of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) and ACAs with minor NEC component (AMiNECs) remains controversial. We aimed to define the behavior and molecular underpinnings of these tumors in comparison with conventional ACAs. In total, 20 NECs, 10 MiNENs, and 8 AMiNECs were compared with 100 controls with ACAs. Well-differentiated neuroendocrine tumors of any grade were excluded. CRCs with NEC components presented at a slightly earlier age (mean, 59 vs 65 years; P = .24) in a similar sex distribution (male:female, 1:1.11 vs 1.04:1; P = .97). The majority of cases arose either from a precursor adenoma (42%) or in the setting of inflammatory bowel disease (18%), whereas 5 of 10 cases (50%) originating from the rectum were human papillomavirus driven. Despite similarity in tumor size and depth of invasion among all groups, CRCs with NEC components showed more frequent lymph node and distant metastases (P < .001 each), leading to more advanced disease stage (stage III/IV; P < .001) and worse 5-year survival outcomes (35.4% for NECs, 30% for MiNENs, and 41.6% for AMiNECs vs 85.1% for ACAs; P < .001), compared with ACAs. Next-generation sequencing revealed more frequent BRAF (40% vs 3%; P < .001) and BRCA1 alterations (15% vs 1%; P = .001) in NECs compared with ACAs. Genomic alterations in RB1 were exclusively found in NECs (10%) and MiNENs (20%). In conclusion, the presence of any NEC component (from AMiNEC to pure NEC) in CRC carries a dismal prognosis. Yet, these tumors are more likely to harbor potentially targetable mutations such as BRAF p.V600E and alterations in BRCA1/2, which are of therapeutic value.

Humans↗

PubMed2026

Epithelial tumor suppressor deletion promotes neuroendocrine differentiation in bladder cancer and reveals homoharringtonine as a candidate vulnerability.

Neuroendocrine bladder carcinoma (NEBC) is a highly aggressive malignancy with unresolved lineage determinants and limited preclinical models, hindering mechanistic investigation and therapeutic development. Here, we sought to assess whether bladder epithelial-derived models are competent to acquire neuroendocrine lineage programs under defined tumor suppressor alterations and to identify candidate therapeutic vulnerabilities in these systems. We integrated genomic and transcriptomic analyses of human NEBC with genetically engineered mouse models, epithelial-derived bladder organoids, and patient-derived NEBC models. Human NEBC exhibited dominant RB1 and TP53 alterations and an epithelial transcriptional continuum consistent with lineage plasticity. In vivo, intravesical Adeno-Cre-mediated tumor suppressor deletion predominantly generated sarcoma-like tumors, whereas epithelial-restricted organoid models recapitulated the molecular and neuroendocrine features of human NEBC, supporting epithelial lineage competence for neuroendocrine differentiation. Patient-derived models and human NEBC specimens further supported epithelial identity in NEBC. Using these complementary platforms, drug screening identified homoharringtonine (HHT) as a candidate therapeutic vulnerability in the tested NEBC systems. HHT suppressed neuroendocrine marker expression, induced apoptosis, and attenuated IL6-JAK-STAT3 signaling. Together, these findings describe complementary epithelial-derived NEBC models and support further investigation of HHT as a candidate therapeutic vulnerability.

Journal Article↗

PubMed2026

Divergent c-MYC Expression Patterns in NET and NEC: Insights from a Multicentre Cohort of 1380 Neuroendocrine Neoplasms.

Neuroendocrine neoplasms (NEN) comprise well-differentiated neuroendocrine tumours (NET) and neuroendocrine carcinomas (NEC), whose distinction is clinically critical. Although c-MYC alterations have been implicated in NEC pathogenesis, c-MYC expression across NEC subtypes and anatomical sites, as well as in NET, remains incompletely defined. We analysed c-MYC immunohistochemically in 1380 resected NEN using the Immunoreactive Score (IRS: negative 0-1, weak 2-3, moderate 4-8, strong 9-12). Overall, c-MYC positivity (IRS ≥ 2) was observed in 13.3% of NEN. Expression was detected in 43% of NEC (164/381), including strong staining in 19.4%, whereas it was rare in NET and pulmonary carcinoids (20/999; 2%; p ≤ 0.001). Within NEC, c-MYC expression was enriched in LCNEC and MiNEN compared with SCNEC and Merkel cell carcinoma (p ≤ 0.001) and occurred more often in gastroenteropancreatic than in pulmonary NEC (57.6% vs. 37.3%; p ≤ 0.001). Among NET, G3 tumours showed the highest positivity rate (6/35; 17.1%), although this was significantly lower than in NEC (p ≤ 0.001), with strong expression observed in only one NET G3 (2.9%). No association between c-MYC expression and survival was identified in either NEC or NET. Our study confirms c-MYC expression as a common event in NEC and highlights differences across histological subtypes and anatomical sites, while demonstrating its absence in most low-proliferative NET. A subset of NET G3 tumours exhibits weak to moderate c-MYC expression at levels far below those seen in NEC, suggesting that strong c-MYC positivity may support a NEC classification in borderline cases but does not represent a definitive discriminatory marker.

Humans↗

PubMed2026

HeteroGeNETics: Neuroendocrine tumor genetics reflect their heterogeneous complex diversity.

Neuroendocrine neoplasms (NENs) comprise a diverse group of malignancies arising across multiple anatomical sites and displaying remarkable biological and clinical heterogeneity. While advances in sequencing have identified recurrent genetic alterations in several NEN subtypes, these tumors remain largely characterized by a relatively low mutational burden and lack of dominant oncogenic drivers. Consequently, emerging evidence suggests that the molecular basis of neuroendocrine tumorigenesis extends beyond individual mutations and involves broader processes such as chromatin remodeling, telomere maintenance, epigenetic dysregulation and cellular plasticity. This review aims to summarize the current molecular landscape of pulmonary, gastro-enteropancreatic and thymic NENs, focusing on the biological pathways and cellular programs disrupted by recurrent genetic alterations unrelated to syndromes. We discuss how multi-omic studies have refined molecular classification and revealed common principles underlying neuroendocrine tumor development. Collectively, recent literature supports a shift from mutation-centered models toward a more integrated understanding of the complex biology and evolution of NENs.

genomics↗

PubMed2026

IASLC Update on Classification of Pulmonary Neuroendocrine Neoplasms.

Since the publication of the 2021 WHO classification of thoracic tumors, our knowledge of pulmonary neuroendocrine neoplasms (NENs) has expanded significantly, particularly through the elucidation of molecular pathways and proposals to refine histopathologic classification. This expanded knowledge across all aspects of pulmonary NENs holds promise for more precise stratification of neuroendocrine tumors (NETs) and the potential development of novel, subtype-specific therapeutic strategies for all NENs. Based on our comprehensive review of the current pulmonary NEN landscape, our multidisciplinary expert panel has deliberated on the modification and updating of the 2021 classification, resulting in the proposal of a new pulmonary carcinoid/NET classification presented in this position paper, which incorporates the following three major points: (1) The proposed framework continues the shift from the traditional carcinoid terminology toward broader adoption of the "NET" nomenclature as found in other organ systems while retaining the term "carcinoid" as the primary diagnostic term to ensure clear communication with thoracic clinical providers. (2) Ki-67 has been incorporated as a diagnostic criterion, aligning with practices in other NET classifications. (3) There is formal recognition of the concept of "carcinoid/NET G3," a rare subset of lung carcinoids characterized by increased proliferative activity but with molecular features more aligned with pulmonary NETs than with high-grade neuroendocrine carcinomas. This position paper on the current knowledge of pulmonary NENs, including the proposed carcinoid/NET classification, will aid in accurate tumor categorization and guide treatment strategies.

Carcinoid tumor↗

PubMed2026

Comprehensive Clinicopathologic, Immunohistochemical, and Genomic Profiling of Sporadic Ampullary Somatostatin-producing D-cell Neuroendocrine Tumors Identifies Recurrent HRAS Hotspot Mutations.

Ampullary somatostatin-producing D-cell neuroendocrine tumors are rare neoplasms that may be associated with type 1 neurofibromatosis. The molecular features of sporadic ampullary somatostatin-producing D-cell neuroendocrine tumors (SAMSOM-NETs) remain poorly characterized. We performed an integrated morphological, immunohistochemical, and genomic analysis of a multicenter series of SAMSOM-NETs. Eleven cases were included (73% male; median age: 63 years). All six patients who underwent lymphadenectomy were staged as pN1, and liver metastases were found in three cases; however, no tumor-related deaths occurred (median follow-up: 104 months). Common histologic features that can pose diagnostic challenges in the differential diagnosis with adenocarcinoma included a tubulo-glandular architecture (100%), periodic Acid-Schiff (PAS)-positive intraluminal mucin (73%), MUC1 expression (100%), and carcinoembryonic antigen (45%) expression. All tumors exhibited dot-like cytoplasmic reactivity for cytokeratins (CK) CAM5.2 or CK AE1/AE3, and 82% were CK7-positive. ISL1 and PDX1 were diffusely expressed in all cases, while CDX2 was positive in 54% and ARX showed only focal expression in four tumors. Genomic profiling revealed microsatellite stability and low tumor mutational burden. Alterations in the RAS pathway, including HRAS mutations (4 cases, 36%), a KRAS mutation (1 case), and NF1 alterations (one case), were identified in 54% of cases and in all tumors with liver metastases. Additional molecular findings included a CDK12 splice-site alteration and an NTRK3::PRDM4 fusion. Potentially actionable alterations affecting kinase-related pathways were detected in 64% of tumors. Our findings support SAMSOM-NET as a peculiar neuroendocrine tumor subtype showing distinctive histologic and molecular characteristics with potential diagnostic and therapeutic implications.

Humans↗

PubMed2026

Grade progression and high-grade transformation in neuroendocrine neoplasms.

Epithelial neuroendocrine neoplasms (NENs) comprise a biologically diverse group of malignancies that span a wide spectrum of differentiation, proliferative activity, and clinical behavior. Contemporary classifications distinguish well-differentiated neuroendocrine tumors (NETs) from poorly differentiated neuroendocrine carcinomas (NECs). However, growing longitudinal data indicate that a subset of NETs may undergo temporal evolution characterized by rising Ki-67, increasing morphologic atypia, and acquisition of genomic alterations classically associated with NEC, particularly TP53 and, less commonly, RB1 inactivation. These phenomena, referred to as grade progression and high-grade transformation, can result in tumors with NEC-like behavior despite retention of a NET molecular backbone, creating diagnostic and therapeutic ambiguity. In this review, we synthesize recent evidence on the molecular, morphologic, and clinical features of gastroenteropancreatic NET grade progression and transformation, highlight the role of clonal evolution and treatment-associated selection pressure, and discuss implications for imaging, biopsy strategy, molecular profiling, and therapy selection.

Humans↗

PubMed2026

PSIP1::TBL1X: a recurrent gene fusion in pancreatic neuroendocrine tumors.

Effective treatment of metastatic neuroendocrine tumors (NETs) is limited by a lack of targeted therapies and clinically useful predictive biomarkers. We applied complementary genomic profiling technologies, including optical genome mapping (OGM) and whole exome sequencing (WES), to 70 liver metastases of NETs from multiple anatomical primary sites to identify actionable genomic alterations. We detected recurrent fusions involving TBL1X (PSIP1::TBL1X) and BEND2 (CHD7::BEND2 and NEO1::BEND2) by OGM in pancreatic neuroendocrine tumors (pNETs). The expression of the PSIP1::TBL1X fusion was confirmed by PacBio Iso-Seq long-read transcriptome sequencing and nested rtPCR, and fusion protein expression was established by western blotting. Expression of the PSIP1::TBL1X fusion was also assayed in a separate cohort of 31 specimens from 28 pNET cases by rtPCR. Across both cohorts, PSIP1::TBL1X was identified in 11% of pNET patients with available metastatic tissue, but was not detected in primary tumor specimens. All PSIP1::TBL1X fusion isoforms were found to retain early exons of PSIP1 and the complete coding sequence of TBL1X. Consistent with prior reports, BEND2 fusions were associated with high-grade tumors and may represent a clinically useful biomarker for aggressive disease. Notably, TBL1X and BEND2 fusions did not co-occur with ATRX/DAXX mutations, defining a distinct molecular subgroup of pNETs. This study highlights the importance of structural variant profiling in molecular profiling studies and supports a revised view of the role of gene fusions in neuroendocrine malignancies.

Humans↗

PubMed2025

Pituitary Neuroendocrine Tumor or Pituitary Adenoma? Let's Ask the Epigenome!

The introduction of the term pituitary neuroendocrine tumor (PitNET) to replace pituitary adenoma has sparked a versatile debate among experts. The controversy surrounding this nomenclature change includes the question of whether these tumors' biological identity truly corresponds to neuroendocrine tumors. In this meta-analysis, DNA methylation data were interrogated to clarify whether the old or new nomenclature more accurately reflects the epigenome of these tumors. Publicly available DNA methylation data of 100 NETs, 100 PitNETs/adenomas, and 100 adenomas of various origins and lineages were compiled from 18 different publications. Epigenomic signatures characteristic of NETs and adenomas were defined and compared to those of PitNETs/adenomas. Promoter CpG methylation levels were investigated for hallmarks of cellular differentiation. Comparative DNA methylation analyses demonstrated that all 100 PitNETs/adenomas aligned more closely with NETs than with adenomas. Focusing on promoter-associated CpGs moreover confirmed robust epigenomic features associated with neuroendocrine differentiation in PitNETs/adenomas. These findings indicate that PitNETs/adenomas resemble NETs rather than adenomas on the epigenomic level and support PitNET as the biologically more accurate term. Of note, appropriately addressing the broad spectrum of clinical behaviors in these tumors remains a critical issue in the current pituitary tumor classification framework and nomenclature.

Humans↗

PubMed2026

Dual Mechanisms Underlie the Repression of Repressor Element 1-Silencing Transcription Factor Expression in Lung Neuroendocrine Carcinoma Cells.

Recent advances in genetic analysis have led to further subtyping of small-cell lung carcinoma (SCLC). The major subtypes of SCLC are the achaete-scute family bHLH transcription factor 1 (ASCL1)-predominant (SCLC-A), neuronal differentiation 1 (NEUROD1)-predominant (SCLC-N), and POU class 2 homeobox 3 (POU2F3) (SCLC-P) subtypes. SCLC-A and SCLC-N tumors express chromogranin A (CHGA) and synaptophysin (SYP), but SCLC-P tumors do not. Large-cell neuroendocrine carcinoma, another type of neuroendocrine carcinoma (NEC), also frequently expresses CHGA and SYP. Because CHGA and SYP expression is controlled by a transrepressor, repressor element 1-silencing transcription factor (REST), the mechanisms underlying REST suppression in NEC were investigated, with a focus on miRNAs and epigenetics, to determine the causes of the differences in the expression of CHGA and SYP between SCLC-A/N and SCLC-P cells. The results showed that miR-375-3p, which was induced by ASCL1 and NEUROD1, repressed REST expression by binding to the 3'-untranslated region of REST mRNA. Bisulfite sequencing and experiments using a DNA methyltransferase inhibitor, a histone deacetylase inhibitor, and chromatin immunoprecipitation-based quantitative PCR revealed that promoter/enhancer hypermethylation and histone deacetylation causes REST gene inactivation in SCLC-A/N. These phenomena were also observed in a large-cell neuroendocrine carcinoma cell line that expressed high levels of ASCL1 and NEUROD1. Taken together, these findings suggest that NEC has dual repressive effects on REST expression, resulting in strict regulation of the expression of CHGA, SYP, and other REST-controlled neuronal/neuroendocrine-specific genes.

Humans↗

PubMed2025

Targeting anti-apoptosis as a therapeutic strategy in neuroendocrine neoplasms.

BCL-2 is an anti-apoptotic protein expressed by aggressive neuroendocrine neoplasms (NENs). We report a case of a patient with a pancreatic neuroendocrine tumor (pNET) who received venetoclax, a BCL-2-targeting drug for the treatment of chronic lymphocytic leukemia. We further characterized BCL2 expression in NENs from a large multi-institutional patient cohort. Clinical data were abstracted from the records of a patient with a pNET. Next-generation sequencing of DNA (592-gene panel or whole exome) and RNA (whole transcriptome) was performed on 636 NENs of pancreatic (P-NENs), small bowel (SB-NENs), colorectal (CR-NENs), and lung (L-NENs) origin by Caris Life Sciences. Comparisons were performed against site-matched non-NEN cancers. BCL2- or MKI67- high and low cohorts were defined based on the top and bottom quartiles of gene expression. The patient with a pNET who received venetoclax had a partial response in the primary tumor that lasted 30 months. CR-, L-, and P-NENs had significantly higher expression of BCL2 compared to non-NEN counterparts. BCL2 expression was significantly higher in MKI67-high tumors among all NEN subtypes. In P-NENs, there was a higher prevalence of RB1 mutations in BCL2-high vs BCL2-low (40 vs 4.9%, P < 0.005). Patients with BCL2-high P-NENs had significantly decreased overall survival (HR 1.94, 95% CI 1.0-3.76, P = 0.047). Immune checkpoint gene expression and T cells were enriched in BCL2-high tumors across all subtypes. In summary, we report the first known case of a pancreatic NET with response to venetoclax. BCL2 expression correlated with high MKI67 expression, worse survival, and a highly immune-enriched microenvironment.

Aged↗

PubMed1979

Neuroendocrine cells in serially passaged rat stomach cancers induced by MNNG.

Five gastric carcinomas, induced in inbred Wistar rats by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) dissolved in drinking water, were successfully transplanted to isologous rats. The transplants grew to a size of 10 to 35 mm in diameter within 8 to 25 weeks of implantation. In one case, serial transplantation were maintained up to the 11th generation, with occurrence of distant metastasis in the 3rd generation. Histological histochemical, and electron microscopical comparison of the original and transplanted tumors revealed that (1) the original tumors were quite well differentiated, forming either papillary or tubular structures, whereas the transplants were more anaplastic and pleomorphic showing often solid nests; and (2) tumor cells with gastrointestinal differentiation and cells with neuroendocrine differentiation were present and evenly distributed in both the original and the serially transplanted tumors. As it is unlikely that the normal and neoplastic neuroendocrine cells are growing side-by-side with and independently of the epithelial neoplastic components in the present series of transplants, the findings strongly suggest (1) the multidirectional potency of the inbred rat stomach carcinoma cells and (2) the common neoplastic origin of the epithelial and neuroendocrine components.

Animals↗

PubMed1979

Altered neuroendocrine status of middle-aged rats prior to the onset of senescent anovulation.

The incidence of senescent anovulation (constant estrus) in female rats increases sharply in the age interval 10--14 months. We have compared the neuroendocrine status of 12-month-old rats, which were still cycling, with that of 6-month-old rats in the reproductive prime. Norepinephrine content in the median eminence of the hypothalamus and circulating levels of FSh and androstenedione were significnatly higher in middle-aged rats (12 months old) than in young controls (6 months old). These increases were selective, in that ten other neuroendocrine parameters measured were unchanged. These results indicate that changes occur at multiple levels of the neuroendocrine system during the transitional phase prior to the onset of senescent anovulation.

Age Factors↗

PubMed1978

Interactions between age and the neuroendocrine and immune systems.

Three conclusions are suggested by some of the recent work on aging, immunology and the neuroendocrine system. 1) There appears to be sufficient data to implicate the neuroendocrine system in both the maturation and the senescence of at least some components of the immune system. 2) The thymus by its presence or its absence appears to influence certain functions of the pituitary; thus, there appears to be a possible reciprocal relationship between the pituitary and the thymus. 3) Changes in the levels of pituitary hormones or hormones that are controlled by the pituitary can restore in older rats and mice certain functions that are generally considered as part of the immune surveillance and defense system. Consequently, it can be hoped that further studies of neuroendocrine-immune relationships might lead to an understanding of some of the causes for the decline in immune competence with age in mammals.

Adrenocorticotropic Hormone↗

PubMed1979

Embryology of the diffuse neuroendocrine system and its relationship to the common peptides.

The diffuse neuroendocrine system is constituted by the cells, now more than 40 in number, of the central and peripheral divisions of the amine precursor uptake and decarboxylation (APUD) series. At one time presumed to be derived from a common "neural" ancestor, all are now deemed to be "neuroendocrine-programmed," arising either in the embryonic epiblast itself or in one of its principal descendants. The APUD cells produce more than 35 physiologically active peptides and a small number of equally active amines. Within the last 3 years, 17 of these peptides have been identified jointly in endocrine cells and in neuronal cell bodies or processes. Sharing in this way a neural and an endocrine location and site of production, they are called the "common peptides." The diffuse neuroendocrine system is to be regarded as a third division of the nervous system, whose products suppress, amplify, or modulate the activities of the other two divisions. The relationship of its products to the cells and processes of these two divisions is currently the object of intensive inquiry.

APUD Cells↗

PubMed2025

Digital Immunophenotyping of Lung Atypical Carcinoids and Large Cell Neuroendocrine Carcinomas Identifies Three Subtypes With Specific Tumor-Immune Microenvironment Features.

Atypical carcinoids (ACs) and large cell neuroendocrine carcinomas (LCNECs) are defined by the WHO as intermediate- and high-grade lung neuroendocrine neoplasms, respectively, based on morphological criteria; however, treatment strategies remain debated. Given the emerging role of the tumor microenvironment (TME) and tumor-infiltrating lymphocytes (TILs) in cancer prognosis and therapy response, this study aimed to characterize the immune landscape of ACs and LCNECs comprehensively. Immunohistochemistry for T-cell markers (CD3, CD8), immune checkpoints (PD-1, PD-L1), HLA molecules (HLA-DR, HLA-I), and fibroblasts (α-SMA) was performed on a re-evaluated cohort of 56 ACs and 104 LCNECs. Digital image analysis quantified intra-tumor (iTILs) and stromal (sTILs) CD3 and CD8 TILs in the whole slide and in specific tumor regions (invasive margin [IM] and central tumor [CT]). LCNECs exhibited significantly higher stromal T-cell infiltration, immune checkpoint expression, and HLA compared to ACs (p < 0.001), while α-SMA was more prominent in ACs. No ACs showed PD-L1 tumor expression. Digital quantification confirmed greater iTILs and sTILs in LCNECs across all regions, with moderate concordance to manual counts. Interestingly, TIL parameters were higher at the IM than in the CT (p < 0.001). Using Boruta feature selection algorithm, Principal Component Analysis and Hierarchical Clustering, three patient clusters were identified: Cluster 1 (mainly ACs, low TILs, favorable prognosis), Cluster 2 (mixed histology, intermediate TILs, moderate prognosis), and Cluster 3 (mostly LCNECs, high TILs, poor prognosis), with distinct TME marker profiles. PD-L1 tumor expression was strongly linked to Cluster 3. These findings suggest that ACs and LCNECs may be stratified into three distinct immune clusters, highlighting the heterogeneity of their tumor microenvironment and providing a rationale for further translational studies.

Humans↗