Genetics-guided therapy in neuroendocrine carcinoma: response to BRAF- and MEK-inhibitors.

Background: Metastatic neuroendocrine carcinoma (NEC) is associated with short survival. Other than platinum-based chemotherapy, there is no clear standard regimen. Current guidelines suggest that combination treatment with BRAF-inhibitors should be considered for patients with BRAF V600E-mutated NEC. However, since only eight such patients have been reported in the literature, our object was to confirm the validity of this recommendation. Methods: This was a single-center retrospective cohort study conducted at Uppsala University Hospital. The included patients 1) had a histopathologically confirmed diagnosis of NEC, 2) were diagnosed between January 1st, 2018 and December 31st, 2023, 3) had tumor tissue genetically screened by a broad next-generation sequencing (NGS) panel, and 4) showed a tumor mutation for which there is a currently available targeted therapy. Results: We screened 48 patients diagnosed with NEC between January 1st, 2018 and December 31st, 2023. Twelve had been analyzed with a broad NGS-panel, and two had a targetable mutation. Both these patients harbored a BRAF V600E-mutated colon-NEC and were treated with BRAF- and MEK-inhibitors dabrafenib and trametinib in second-line. At first radiological evaluation (RECIST 1.1), both patients had a reduction of tumor size, which decreased by 31 and 40%. Both had short response periods, and their overall survival was 12 and 9 months. Conclusions: BRAF-mutated NEC is sensitive to treatment with BRAF- and MEK-inhibitor combination. These results further support that DNA sequencing should be considered as standard of care in NECs to screen for potential treatment targets.

Head-to-head: Should Ki67 proliferation index be included in the formal classification of pulmonary neuroendocrine neoplasms?

The reporting of lung neuroendocrine neoplasms (NENs) according to the 2021 World Health Organisation (WHO) is based on mitotic count per 2 mm2, necrosis assessment and a constellation of cytological and immunohistochemical details. Accordingly, typical carcinoid and atypical carcinoid are low- to intermediate-grade neuroendocrine tumours (NETs), while large-cell neuroendocrine carcinoma (NEC) and small-cell lung carcinoma are high-grade NECs. In small-sized diagnostic material (cytology and biopsy), the noncommittal term of carcinoid tumour/NET not otherwise specified (NOS) and metastatic carcinoid NOS have been introduced with regard to primary and metastatic diagnostic settings, respectively. Ki-67 antigen, a well-known marker of cell proliferation, has been included in the WHO classification as a non-essential but desirable criterion, especially to distinguish NETs from high-grade NECs and to delineate the provisional category of carcinoid tumours/NETs with elevated mitotic counts (> 10 mitoses per mm2) and/or Ki-67 proliferation index (≥ 30%). However, a wider use of this marker in the spectrum of lung NENs continues to be highly reported and debated, thus witnessing a never-subsided attention. Therefore, the arguments for and against incorporating Ki-67 in the classification and clinical practice of these neoplasms are discussed herein in detail.

Histopathological Features Predicting Neuroendocrine Morphology in Primary Breast Tumors: A Retrospective Analysis.

Objective: Neuroendocrine neoplasms of primary breast tumors are rare compared to locations, such as the respiratory system and gastrointestinal system, where they are frequently observed. The diagnostic criteria for primary neuroendocrine tumors of the breast have been changed since first description. Morphological and immunohistochemical features helpful in their diagnosis, which vary due to the heterogeneous nature of these tumors, are highlighted in this retrospective study. The purpose was to determine specific histopathological features that can identify neuroendocrine morphology in primary breast tumors. Materials and Methods: Cases diagnosed with invasive breast carcinoma from resection materials in a single center between 2011 and 2022 and in which neuroendocrine markers were investigated were included. Demographic information, initial histopathological diagnosis, presence of tumor in another organ, tumor location, size and surgical details of the cases were obtained from the hospital database and pathology reports. The slides were re-evaluated in terms of tumor growth pattern, cribriformity, tubule formation, nuclear features, prominence of nucleoli, palisading and basal location of nuclei, presence of grooves, cytoplasmic features and evidence of cytoplasmic border. Results: The presence of basally located nuclei, absence of tubule formation, inconspicuous nucleoli, fine nuclear chromatin, granular cytoplasm and inconspicuous cytoplasmic borders were frequent findings in tumors with neuroendocrine features (p<0.05). These features may help differentiate primary breast tumors with neuroendocrine features from other breast carcinomas. Conclusion: The histopathological features that are different from the specific features seen in classical neuroendocrine tumors, the absence of specific clinical and radiological findings, the inability to study neuroendocrine markers in every laboratory and the need to prove that the breast tumor is not a metastasis all create diagnostic difficulties for primary breast neuroendocrine neoplasms. We believe that the results of this study may help diagnose and identify more specific histomorphological features that help determine neuroendocrine morphology in primary breast tumors.

Prognostic factors and predictive models for patients with lung large cell neuroendocrine carcinoma: Based on SEER database.

BACKGROUND: Lung Large cell neuroendocrine carcinoma (LCNEC) is a rare, aggressive, high-grade neuroendocrine carcinoma with a poor prognosis, mainly seen in elderly men. To date, we have found no studies on predictive models for LCNEC. METHODS: We extracted data from the Surveillance, Epidemiology, and End Results (SEER) database of confirmed LCNEC from 2010 to 2018. Univariate and multivariate Cox proportional risk regression analyses were used to identify independent risk factors, and then we constructed a novel nomogram and assessed the predictive effectiveness by receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). RESULTS: A total of 2546 patients with LCNEC were included, excluding those diagnosed with autopsy or death certificate, tumor, lymph node, metastasis (TNM) stage, tumor grade deficiency, etc., and finally, a total of 743 cases were included in the study. After univariate and multivariate analyses, we concluded that the independent risk factors were N stage, intrapulmonary metastasis, bone metastasis, brain metastasis, and surgical intervention. The results of ROC curves, calibration curves, and DCA in the training and validation groups confirmed that the nomogram could accurately predict the prognosis. CONCLUSIONS: The nomogram obtained from our study is expected to be a useful tool for personalized prognostic prediction of LCNEC patients, which may help in clinical decision-making.

Poorly differentiated neuroendocrine carcinoma originating in the subglottic larynx: A case report with imm unohistochemical study.

Key Clinical Message: Laryngeal neuroendocrine carcinomas are the most common non-squamous neoplasm of the larynx. Due to the rarity of the tumor, pathological diagnosis should be confirmed by immunohistochemistry. Abstract: Laryngeal neuroendocrine carcinomas (LNECs) are a rare cancer of the head and neck. Few case reports of poorly differentiated neuroendocrine carcinoma originating in the subglottic larynx exist within the literature. In this case, we discuss a 57-year-old patient with a history of four-month hoarseness with a newly diagnosed of poorly differentiated neuroendocrine carcinoma in the subglottic larynx. Treatment and prognosis of the various NEC groups differ, so precise identification requires consideration of the microscopic findings and immunostaining analysis. immunohistochemistry staining demonstrated positive result for cytokeratin 7, synaptophysin, chromogranin, CD 56, with the Ki-67 index of45%. Although surgery is usually the treatment for all tumor types, chemo radiotherapy is recommended for poorly differentiated NECs because surgery is ineffective.

Synchronous Double Primary Tumors of Liver (Small Cell Neuroendocrine Carcinoma and Hepatocellular carcinoma): A Case Report.

This study presents a case of dual primary liver cancer involving small cell neuroendocrine carcinoma and hepatocellular carcinoma. The 58-year-old Chinese male patient, who has a medical history of viral hepatitis B, presented with right upper abdominal pain persisting for one month. Imaging studies indicated the presence of multiple liver masses in segments V and VII-VIII, as well as a mass in the left lung. Subsequent hepatic biopsy performed on both segments confirmed the presence of hepatocellular carcinoma in segment V and small cell neuroendocrine carcinoma in segment VII-VIII. After undergoing one cycle of chemotherapy, the lung mass exhibited a reduction in size, while the liver masses showed an inadequate response. Subsequently, the patient underwent Transcatheter Arterial Chemoembolization (TACE) and Hepatic Artery Infusion Chemotherapy (HIAC), resulting in partial remission (PR). However, the patient was diagnosed with brain metastasis and subsequently treated with Sorafenib and Tirelizumab, a Programmed Death 1 (PD-1) immune checkpoint inhibitor. The efficacy evaluation indicated stability, and no severe adverse effects were observed at the time of writing. The patient's survival time was 16 months.

Primary Small-Cell Carcinoma of the Urinary Bladder: A Case Report and Literature Review.

Small-cell carcinoma of the bladder (SCCB) is an uncommon and aggressive malignancy of the urinary tract. Its clinical presentation often mimics that of other bladder neoplasms, posing a diagnostic challenge. This case report presents a rare instance of SCCB in a 65-year-old female, shedding light on the diagnostic journey and emphasizing the need for heightened and prompt clinical suspicion due to its aggressive nature. The patient presented to the urological department with hematuria, dysuria, and hypogastric pain. Initial investigations revealed a bladder mass, prompting biopsies with inconclusive results. A comprehensive histopathological examination, including immunohistochemistry, confirmed a SCCB. A computed tomography (CT) scan was used to evaluate local and distal extention. Following the initial evaluation, a referral to an oncological service was needed. Diagnoses encompassed SCCB, with interventions that comprise chemotherapy without radical cystectomy. Despite the rarity of SCCB, timely and accurate diagnosis facilitated a tailored multidisciplinary approach, leading to prompt clinical oncology management. This case demonstrates the importance of meticulous diagnostic evaluation in rare malignancies, guiding individualized therapeutic strategies for optimal patient outcomes.

Evaluation of association between center colorectal neuroendocrine neoplasm volume and survival among patients with colorectal neuroendocrine carcinoma.

BACKGROUND: Although correlation between center volume and survival has been reported for several complex cancers, it remains unknown if this is true for colorectal neuroendocrine carcinomas (CRNECs). We hypothesized that higher center annual volume of colorectal neuroendocrine neoplasm resections would be associated with overall survival (OS) for patients with CRNECs. METHODS: Patients in the National Cancer Database diagnosed with stages I-III CRNEC between 2006 and 2018 and who underwent surgical resection were identified. The mean annual colorectal neuroendocrine neoplasm resection volume threshold associated with significantly worse mortality hazard was determined using restricted cubic splines. Kaplan-Meier (KM) method was used to compare OS, while Cox proportional hazards model was used for multivariable analysis. RESULTS: There were 694 patients with CRNEC who met inclusion criteria across 1229 centers. Based on the cubic spline, centers treating fewer than one colorectal neuroendocrine neoplasm patient every 3 years on average had worse outcomes. Centers below this threshold were classified as low-volume (LV) centers corresponding with 42% of centers and about 15% of the patient cohort. In unadjusted survival analysis, LV patients had a median OS of 14 months (95% confidence interval [CI]: 10-19) while those treated at HV centers had a median OS of 33 months (95% CI: 25-49). In multivariable analysis, resection at a LV center was associated with increased risk of mortality (1.42 [95% CI: 1.01-2.00], p = 0.04). CONCLUSION: CRNEC patients have a dire prognosis; however, treatment at an HV center may be associated with decreased risk of mortality.

Lethal disseminated intravascular coagulation induced by primary and metastatic neuroendocrine prostate cancer.

Introduction: Neuroendocrine prostate cancer has a poor prognosis. Although disseminated intravascular coagulation associated with malignancy can be lethal, it very rarely occurs among patients with primary neuroendocrine prostate cancer. Case presentation: An 80-year-old man presented to our hospital with bloody sputum. Blood examination indicated disseminated intravascular coagulation. Serum levels of prostate-specific antigen and neuron-specific enolase were 44.274 and 176 ng/mL, respectively. Core needle biopsies of an irregular mass in the prostate and a metastatic tumor in the left iliac bone showed similar neuroendocrine carcinoma cells. Hence, the patient was diagnosed with disseminated intravascular coagulation associated with primary and metastatic neuroendocrine prostate cancer. Unfortunately, he passed away 3 weeks after the biopsies. Conclusion: Given the difficulty of effectively treating metastatic neuroendocrine prostate cancer among patients in poor physical condition due to disease progression, identifying a new well-tolerated treatment modality is imperative.

Response to capmatinib in a patient with neuroendocrine carcinoma of the gallbladder origin harboring MET amplification.

Neuroendocrine carcinoma (NEC) of the gallbladder origin is particularly rare, accounting for only 0.38% of primary malignancies of the gallbladder, and standard therapies are limited. The MET gene encodes the tyrosine kinase receptor, c-Met. Pathogenic variants of MET, such as MET exon 14 skipping and MET amplification, result in excessive downstream signaling that promotes tumor progression. A MET inhibitor, capmatinib, blocks signaling of c-Met and has been approved by the Food and Drug Administration for non-small cell lung cancer with MET exon 14 skipping. The effectiveness of capmatinib has been reported in other cancers with MET amplification, but NEC with MET variants has not been reported. Here, we present a case of a 72-year-old woman with NEC of the gallbladder with multiple liver and lymph node metastases, who was resistant to conventional chemotherapy including carboplatin plus etoposide as first-line treatment and irinotecan as second-line treatment, but she responded to capmatinib. After 6 weeks of treatment, CT scan showed a partial response (80% reduction in size), but after 13 weeks, regrowth of liver metastasis was observed. Herein, we report a meaningful efficacy of capmatinib to the patient of NEC of the gallbladder origin with MET amplification.

An unexpected case of large cell neuroendocrine carcinoma of the colon: a case report.

Background: Patients presenting with large cell neuroendocrine carcinomas (LCNECs) comprise a small minority of total colon and rectal cancers (1-2%) with poor prognostic outcomes in lieu of late diagnosis and metastasis at the point of diagnosis. Case Description: We report a case presentation of a 69-year-old male presenting with diffuse, non-severe upper abdominal pain and a positive at-home colon cancer screening test. At the time of presentation, the patient was negative for constipation or blood in stool. The patient underwent a colonoscopy with biopsy results positive for LCNEC within the proximal ascending colon. A right hemicolectomy was performed with subsequent pathology indicating a poorly differentiated LCNEC with 4/18 positive nodes and final pathology showing stage IIIA (T3, N1, M0) with Ki-67 index at 70%. Post-operative intervention included two cycles of carboplatin and etoposide as well as routine follow-up for labs, imaging, and pharmacological management. Conclusions: LCNECs are highly aggressive with poor prognostic outcomes and high mortality rates on both 1- and 5-year survival scales. Prior studies and reports indicated a need for further research and data investigating treatment standardization for patients diagnosed with LCNECs. In lieu of this, this study provides a potential standardized treatment modality combining both European Neuroendocrine Tumor Society (ENETS) and North American Neuroendocrine Tumor Society (NANETS) consensus guidelines.

A prognostic nomogram based on least absolute shrinkage and selection operator Cox regression in patients with pulmonary large-cell neuroendocrine carcinoma.

Background: Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is a rare subtype of breast cancer with a poor prognosis. Despite its rarity, it is important to gain a better understanding of the epidemiological, clinical, and prognostic features of pulmonary LCNEC. The purpose of this study was to design, construct, and validate a new nomogram for predicting overall survival (OS) in patients with pulmonary LCNEC. Methods: In total, the data of 1,864 LCNEC patients were extracted from the Surveillance, Epidemiology, and End Results (SEER) database, which is maintained by the National Cancer Institute in the United States and serves as a comprehensive source of cancer-related information. Of these patients, 556 served as the validation group and 1,308 served as the training cohort. We constructed a new nomogram with the training cohort that included the independent factors for OS as identified by least absolute shrinkage and selection operator Cox regression. Five independent factors were ultimately selected by the stepwise regression. Every factor of the Cox regression was included in the nomogram. Analyses of the calibration curve, decision curve, area under the curve, and concordance index (C-index) values were performed to assess the effectiveness and discriminative ability of the nomogram. Results: Five optimal predictive factors for OS were selected and merged to construct a 3- and 5-year OS nomogram. The nomogram had C-index values of 0.716 and 0.708 in the training cohort and validation cohort, respectively. The actual OS rates and the calibration curves showing the predictions of the nomogram were in good agreement. Conclusions: The prognostic nomogram may be very helpful in estimating the OS of patients with pulmonary LCNEC.

Advances in genetic profile and therapeutic strategy of pulmonary large cell neuroendocrine carcinoma.

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a high-grade neuroendocrine carcinoma (HGNEC) accounting for 3% of primary lung cancer, and characterized by strong invasion, high heterogeneity, and extremely poor prognosis. At present, the diagnosis and treatment of LCNEC remains controversial and refer to therapeutic strategy of small cell lung cancer (SCLC), lacking precise therapy. Recently, the genetic analysis and clinical trials of LCNEC gradually emerged, providing more evidence for precise diagnosis and treatment. Here, we review the diagnosis, molecular characteristics, and treatment of LCNEC based on the existing research and frontier progress to provide a potential direction for future diagnosis and treatment of LCNEC.

Clinical analysis of 12 cases of ovarian neuroendocrine carcinoma.

BACKGROUND: Neuroendocrine neoplasms of the female genital tract are rare. AIM: To enhance our clinical understanding of neuroendocrine carcinoma (NEC) of the ovary. METHODS: A retrospective review was conducted on 12 patients diagnosed with NEC of the ovary, analyzing clinicopathological characteristics, treatment modalities, and survival status. RESULTS: The median age at diagnosis was 34.5 years (range: 20 to 62 years). Among the 12 cases, 9 were small cell carcinoma of the ovary and 3 were large cell NEC. Five cases were stage I tumors, one case was stage IV, and six cases were stage III. Eleven patients underwent surgery as part of their treatment. All patients received adjuvant chemotherapy. Among the 12 patients, one patient received radiotherapy, and one patient with a BRCA2 mutation was administered PARP inhibitor maintenance after chemotherapy. The median progression-free survival was 13 months, and the median overall survival was 19.5 months. Four cases remained disease-free, while eight cases experienced tumor recurrence, including three cases that resulted in death due to disease recurrence. CONCLUSION: NEC of the ovary is a rare condition that is more common in women of childbearing age and is associated with aggressive behavior and poor clinical outcomes. Surgical resection remains the mainstay of treatment, with some patients benefiting from adjuvant chemoradiation therapy.

Molecular Classification of Gastrointestinal and Pancreatic Neuroendocrine Neoplasms: Are We Ready for That?

In the last two decades, the increasing availability of technologies for molecular analyses has allowed an insight in the genomic alterations of neuroendocrine neoplasms (NEN) of the gastrointestinal tract and pancreas. This knowledge has confirmed, supported, and informed the pathological classification of NEN, clarifying the differences between neuroendocrine carcinomas (NEC) and neuroendocrine tumors (NET) and helping to define the G3 NET category. At the same time, the identification genomic alterations, in terms of gene mutation, structural abnormalities, and epigenetic changes differentially involved in the pathogenesis of NEC and NET has identified potential molecular targets for precision therapy. This review critically recapitulates the available molecular features of digestive NEC and NET, highlighting their correlates with pathological aspects and clinical characteristics of these neoplasms and revising their role as predictive biomarkers for targeted therapy. In this context, the feasibility and applicability of a molecular classification of gastrointestinal and pancreatic NEN will be explored.

A systematic review of primary large cell neuroendocrine carcinoma of the prostate.

Background: Large cell neuroendocrine carcinoma (LCNEC) is a rare subtype of prostate cancer. The pathogenesis, clinical manifestation, treatment options, and prognosis are uncertain and underreported. Materials and methods: A systematic search was conducted in April 2022 through PubMed, Embase, and Cochrane. We reviewed cases of LCNEC developed either from de novo or transformation from prostate adenocarcinoma and summarized the relevant pathophysiological course, treatment options, and outcomes. Results: A total of 25 patients with a mean age of 70.4 (range 43 87 years old) from 18 studies were included in this review. 13 patients were diagnosed with de novo LCNEC of the prostate. 12 patients were from the transformation of adenocarcinoma post-hormonal therapy treatment. Upon initial diagnosis, patients diagnosed with de novo prostatic LCNEC had a mean serum PSA value of 24.6 ng/ml (range: 0.09-170 ng/ml, median 5.5 ng/ml), while transformation cases were significantly lower at 3.3 ng/ml (range: 0-9.3 ng/ml, median 0.05 ng/ml). The pattern of metastasis closely resembles prostate adenocarcinoma. Six out of twenty-three cases displayed brain metastasis matching the correlation between neuroendocrine tumors and brain metastasis. Three notable paraneoplastic syndromes included Cushings syndrome, dermatomyositis, and polycythemia. Most patients with advanced metastatic disease received conventional platinum-based chemotherapy with a mean survival of 5 months. There was one exception in the transformation cohort with a somatic BRCA2 mutation who was treated with a combination of M6620 and platinum-based chemotherapy with an impressive PFS of 20 months. Patients with pure LCNEC phenotype have worse survival outcomes when compared to those with mixed LCNEC and adenocarcinoma phenotypes. It is unclear whether there is a survival benefit to administering ADT in pure pathologies. Conclusion: LCNEC of the prostate is a rare disease that can occur de novo or transformation from prostatic adenocarcinoma. Most patients present at an advanced stage with poor prognosis and are treated with conventional chemotherapy regimens. Patients who had better outcomes were those who were diagnosed at an early stage and received treatment with surgery or radiation and androgen deprivation therapy (ADT). There was one case with an exceptional outcome that included a treatment regimen of M6620 and chemotherapy.

Patient-derived tumoroid models of pulmonary large-cell neuroendocrine carcinoma: a promising tool for personalized medicine and developing novel therapeutic strategies.

Pulmonary large-cell neuroendocrine carcinoma (LCNEC), a disease with poor prognosis, is classified as pulmonary high-grade neuroendocrine carcinoma, along with small-cell lung cancer. However, given its infrequent occurrence, only a limited number of preclinical models have been established. Here, we established three LCNEC tumoroids for long-term culture. Whole-exome sequencing revealed that these tumoroids inherited genetic mutations from their parental tumors; two were classified as small-cell carcinoma (S-LCNEC) and one as non-small cell carcinoma (N-LCNEC). Xenografts from these tumoroids in immunodeficient mice mimicked the pathology of the parent LCNEC, and one reproduced the mixed-tissue types of combined LCNEC with a component of adenocarcinoma. Drug sensitivity tests using these LCNEC tumoroids enabled the evaluation of therapeutic agent efficacy. Based on translational research, we found that a CDK4/6 inhibitor might be effective for N-LCNEC and that Aurora A kinase inhibitors might be suitable for S-LCNEC or LCNEC with MYC amplification. These results highlight the value of preclinical tumoroid models in understanding the pathogenesis of rare cancers and developing treatments. LCNEC showed a high success rate in tumoroid establishment, indicating its potential application in personalized medicine.

Small Cell Non-keratinizing Neuroendocrine Carcinoma Involving the Larynx and the Base of the Tongue: A Rare Case With a Locally Aggressive Spread.

Squamous cell carcinoma is the most predominant type of malignancy in the head and neck region with neuroendocrine carcinomas (NECs) being a rare occurrence. Here we report a rare case of small cell non-keratinizing NEC (WHO grade 3), TNM (tumor, node, and metastasis) stage T3N1M0, involving the larynx and the base of the tongue, in a 54-year-old male patient, demonstrating its rarity in an uncommon anatomical site and an aggressive and relatively uncommon pattern of spread for this tumor, over a period of two months. NECs in the head and neck region, especially those affecting the larynx and the posterior third of the tongue, remain exceedingly rare, comprising only a small fraction of malignancies in this region. The aggressive nature and distinct pattern of spread observed in this case underscore the importance of recognizing such unusual presentations for appropriate diagnosis and management. Given the rarity of this tumor type, a comprehensive understanding of its clinicopathological features is essential for guiding effective treatment strategies. We also discuss the treatment.

Esophageal squamous cell carcinoma transformed into neuroendocrine carcinoma after neoadjuvant immunochemotherapy: A case report.

Immunotherapy provides durable responses for locally advanced esophageal carcinoma clinical therapy in numerous patients. However, the mechanisms of resistance to immunotherapy have not been elucidated. The phenomenon of the histological transformation of non-small cell lung cancer to small cell lung cancer resulting in resistance to immune checkpoint inhibitors (ICIs) has been reported. It remains unclear whether ICIs or chemotherapy could cause a similar transformation from esophageal squamous cell carcinoma (ESCC) to esophageal neuroendocrine carcinoma (ENEC). The present study report the case of a patient initially diagnosed with stage II ESCC who underwent radical surgery after three cycles of neoadjuvant therapy with cisplatin, albumin bound paclitaxel and ICIs. Immunohistochemical staining confirmed the absence of the SCC component and the presence of the NEC component, with negativity for CK5/6 and tumor protein p40, but positive expression of tumor protein p53, pan-cytokeratin, synaptophysin and CD56. The patient was followed up for 5 months with no treatment or postoperative complications. In conclusion, histological transformation to ENEC is a potential mechanism of acquired resistance to ICIs in ESCC. Prospective larger studies are warranted to further characterize ESCC-to-NEC transformation on use of ICIs.