Perioperative outcomes and survival of modified subxiphoid video-assisted thoracoscopic surgery thymectomy for T2-3 thymic malignancies: A retrospective comparison study.

OBJECTIVE: Our previous study demonstrated that modified subxiphoid video-assisted thoracic surgery thymectomy with an auxiliary sternal retractor is feasible for locally invasive thymic malignancies. This study aimed to compare perioperative and oncological outcomes of modified subxiphoid video-assisted thoracoscopic surgery thymectomy versus median sternotomy thymectomy for locally advanced thymic malignancies. METHODS: In total, 221 patients with T2-3 thymic malignancies who underwent modified subxiphoid video-assisted thoracoscopic surgery thymectomy or median sternotomy thymectomy between 2015 and 2020 were enrolled in our prospectively maintained database. A 1:1 propensity score-matching analysis was performed to balance the bias. Surgical difficulty was evaluated with a modified resection index. Perioperative and oncological results were compared between the modified subxiphoid video-assisted thoracoscopic surgery thymectomy group and the median sternotomy thymectomy group. RESULTS: There were 72 patients in each group in the final analysis. Our results showed that the modified subxiphoid video-assisted thoracoscopic surgery thymectomy group had a shorter operative duration (98 vs 129 minutes, P < .001), less blood loss (40 vs 100 mL, P < .001), shorter drainage duration (3 vs 5 days, P < .001), shorter length of hospital stay (5 vs 6 days, P < .001), and fewer postoperative complications (5.6% vs 23.6%; P = .005). No significant difference was detected in complete resection (98.6% vs 98.6%, P = 1.000) between the 2 groups. Conversion occurred in 5 of 106 patients (4.7%). Survival analyses indicated similar recurrence-free survival (hazard ratio, 0.94; 95% CI, 0.40-2.20; P = .883) and overall survival (hazard ratio, 0.52; 95% CI, 0.05-5.02; P = .590) between the 2 groups. CONCLUSIONS: Modified subxiphoid video-assisted thoracoscopic surgery thymectomy was safe and effective for T2-3 thymic malignancies and could be an alternative for selected patients with locally advanced thymic diseases. Further prospective studies are needed to evaluate the long-term survival of those undergoing modified subxiphoid approach thoracoscopic thymectomy.

Exosomal NAT10 from esophageal squamous cell carcinoma cells modulates macrophage lipid metabolism and polarization through ac4C modification of FASN.

N-acetyltransferase 10 (NAT10) is acknowledged as a tumor promoter in various cancers due to its role as a regulator of acetylation modification. Tumor-associated macrophages (TAMs) play a pivotal role in the tumor microenvironment (TME). However, the intercellular communication between esophageal squamous cell carcinoma (ESCC) cells and TAMs involving NAT10 remains poorly understood. This study aimed to elucidate the regulatory mechanism of NAT10 in modulating macrophage lipid metabolism and polarization. Experimental evidence was derived from in vitro and in vivo analyses. We explored the association between upregulated NAT10 in ESCC tissues, macrophage polarization, and the therapeutic efficacy of PD-1. Furthermore, we investigated the impact of methyltransferase 3 (METTL3)-induced m6A modification on the increased expression of NAT10 in ESCC cells. Additionally, we examined the role of exosomal NAT10 in stabilizing the expression of fatty acid synthase (FASN) and promoting macrophage M2 polarization through mediating the ac4C modification of FASN. Results indicated that NAT10, packaged by exosomes derived from ESCC cells, promotes macrophage M2 polarization by facilitating lipid metabolism. In vivo animal studies demonstrated that targeting NAT10 could enhance the therapeutic effect of PD-1 on ESCC by mediating macrophage reprogramming. Our findings offer novel insights into improving ESCC treatment through NAT10 targeting.

WHO histological classification and tumor size are predictors of the locally aggressive behavior of thymic epithelial tumors.

OBJECTIVE: The aim of this study was to explore the influencing factors that affect the local invasive behavior of thymic epithelial tumors (TETs). METHOD: We retrospectively analyzed 524 patients with TETs who underwent surgical treatment at our center from January 2010 to January 2022. Cox regression analysis was applied to identify predictors associated with the prognosis of TET. Logistic regression analysis was used to analyze the factors associated with the locally invasive behavior of TETs. Receiver operating characteristic analysis and the Youden index were applied to determine the predictive efficiency and cutoff value. RESULTS: There were 275 males and 249 females with a median age of 56 years. Seventy-seven patients had locally invasive behavior. The prognosis of local invasive TETs was significantly worse that of noninvasive TETs (P < 0.001). WHO classification and tumor size were two hazard factors for tumor invasive behavior. The risk of local invasion increased by 2.196 (OR (95 % CI): 1.813-2.659) times for each grade in WHO classification with a change from type A to thymic carcinoma. The tumor size cutoff of 6 cm represented a distinct boundary in predicting the hazard of local invasion (AUC: 0.784, specificity: 0.711, sensitivity: 0.726). CONCLUSION: WHO classification and tumor size are important factors in predicting the locally aggressive behavior of TETs. The invasion capability of TETs is constantly increasing with an escalation in WHO classification. Tumors greater than 6 cm in size have a higher risk for local invasion.

ASCC3 promotes the immunosuppression and progression of non-small cell lung cancer by impairing the type I interferon response via CAND1-mediated ubiquitination inhibition of STAT3.

BACKGROUND: Activating signal cointegrator 3 (ASCC3) has been identified as an oncogenic factor that impairs host immune defense. However, the underlying mechanisms of carcinogenesis and its impact on the antitumor immune response remain unclear. In this study, we aimed to investigate the molecular mechanisms of ASCC3 in the progression of non-small cell lung cancer (NSCLC). METHODS: Single-cell sequencing data from the Gene Expression Omnibus and gene expression profiles from The Cancer Genome Atlas database were analyzed. The expression, clinical relevance and biological functions of ASCC3 in NSCLC were explored. Then, RNA sequencing, immunoprecipitation, mass spectrometry, immunofluorescence, and flow cytometry analyses were conducted to explore the underlying molecular mechanisms. In addition, in vivo experiments in mouse models were conducted to explore the probability of ASCC3 knockdown to improve the efficacy of anti-Programmed Death-1 (PD-1) therapy in NSCLC. RESULTS: ASCC3 was significantly upregulated in NSCLC and correlated with poor pathological characteristics and prognosis in patients with NSCLC. Overexpression of ASCC3 promoted malignant phenotypes of NSCLC cells and induced an immunosuppressive tumor microenvironment, which was characterized by a decrease in CD8+ T cells, natural killer cells and dendritic cells but an increase in regulatory T(Treg) cells. Mechanistically, ASCC3 stabilized signal transducer and activator of transcription (STAT)3 signaling by recruiting Cullin-associated and neddylation dissociated 1 (CAND1), which inhibited ubiquitin-mediated degradation of STAT3, thereby impairing the type I interferon response of tumor cells and promoting the immunosuppression and progression of NSCLC. Furthermore, high expression of ASCC3 impaired the efficacy of anti-PD-1 therapy, and an anti-PD-1 antibody combined with ASCC3 knockdown exerted promising synergistic efficacy in a preclinical mouse model. CONCLUSION: ASCC3 could stabilize the STAT3 pathway via CAND1, reshaping the tumor microenvironment and inducing resistance to anti-PD-1 therapy, which promotes the progression of NSCLC. It is a reliable prognostic indicator and can be a target in combination therapy for NSCLC.

Comprehensive landscape and future perspective of long noncoding RNAs in non-small cell lung cancer: it takes a village.

Long noncoding RNAs (lncRNAs) are a distinct subtype of RNA that lack protein-coding capacity but exert significant influence on various cellular processes. In non-small cell lung cancer (NSCLC), dysregulated lncRNAs act as either oncogenes or tumor suppressors, contributing to tumorigenesis and tumor progression. LncRNAs directly modulate gene expression, act as competitive endogenous RNAs by interacting with microRNAs or proteins, and associate with RNA binding proteins. Moreover, lncRNAs can reshape the tumor immune microenvironment and influence cellular metabolism, cancer cell stemness, and angiogenesis by engaging various signaling pathways. Notably, lncRNAs have shown great potential as diagnostic or prognostic biomarkers in liquid biopsies and therapeutic strategies for NSCLC. This comprehensive review elucidates the significant roles and diverse mechanisms of lncRNAs in NSCLC. Furthermore, we provide insights into the clinical relevance, current research progress, limitations, innovative research approaches, and future perspectives for targeting lncRNAs in NSCLC. By summarizing the existing knowledge and advancements, we aim to enhance the understanding of the pivotal roles played by lncRNAs in NSCLC and stimulate further research in this field. Ultimately, unraveling the complex network of lncRNA-mediated regulatory mechanisms in NSCLC could potentially lead to the development of novel diagnostic tools and therapeutic strategies.

Tumor-infiltrating CD36+CD8+T cells determine exhausted tumor microenvironment and correlate with inferior response to chemotherapy in non-small cell lung cancer.

BACKGROUND: The scavenger receptor CD36 was reported to be highly expressed on tumor-infiltrating CD8+ T cells, but the clinical role remains obscure. This study aims to explore the infiltration and clinical value of CD36+CD8+ T cells in NSCLC. METHODS: Immunohistochemistry and immunofluorescence were conducted for survival analyses and immunological evaluation in 232 NSCLC patients in Zhongshan Hospital. Flow cytometry analyses were carried out to assess the immune cells from fresh tumor samples, non-tumor tissues and peripheral blood. In vitro tumor infiltrating lymphocytes cultures were conducted to test the effect of CD36 blockage. RESULTS: Accumulation of CD36+CD8+ T cells in tumor tissues was correlated with more advanced stage (p < 0.001), larger tumor size (p < 0.01), and lymph node metastasis (p < 0.0001) in NSCLC. Moreover, high infiltration of CD36+CD8+ T cells indicated poor prognosis in terms of both overall survival (OS) and recurrence-free survival (RFS) and inferior chemotherapy response. CD36+CD8+ T cells showed decreased GZMB (p < 0.0001) and IFN-γ (p < 0.001) with elevated PD-1 (p < 0.0001) and TIGIT (p < 0.0001). Analysis of tumor-infiltrating immune cell landscape revealed a positive correlation between CD36+CD8+ T cells and Tregs (p < 0.01) and M2-polarized macrophages (p < 0.01) but a negative correlation with Th1 (p < 0.05). Notably, inhibition of CD36 partially restored the cytotoxic function of CD8+ T cells by producing more GZMB and IFN-γ. CONCLUSION: CD36+CD8+ T cells exhibit impaired immune function and high infiltration of CD36+CD8+ T cells indicated poor prognosis and inferior chemotherapy response in NSCLC patients. CD36 could be a therapeutic target in combination with chemotherapy in NSCLC patients.

Immunotherapy of thymic epithelial tumors: molecular understandings and clinical perspectives.

Immunotherapy has emerged to play a rapidly expanding role in the treatment of cancers. Currently, many clinical trials of therapeutic agents are on ongoing with majority of immune checkpoint inhibitors (ICIs) especially programmed death receptor 1 (PD-1) and its ligand 1 (PD-L1) inhibitors. PD-1 and PD-L1, two main immune checkpoints, are expressed at high levels in thymic epithelial tumors (TETs) and could be predictors of the progression and immunotherapeutic efficacy of TETs. However, despite inspiring efficacy reported in clinical trials and clinical practice, significantly higher incidence of immune-related adverse events (irAEs) than other tumors bring challenges to the administration of ICIs in TETs. To develop safe and effective immunotherapeutic patterns in TETs, understanding the clinical properties of patients, the cellular and molecular mechanisms of immunotherapy and irAEs occurrence are crucial. In this review, the progress of both basic and clinical research on immune checkpoints in TETs, the evidence of therapeutic efficacy and irAEs based on PD-1 /PD-L1 inhibitors in TETs treatment are discussed. Additionally, we highlighted the possible mechanisms underlying irAEs, prevention and management strategies, the insufficiency of current research and some worthy research insights. High PD-1/PD-L1 expression in TETs provides a rationale for ICI use. Completed clinical trials have shown an encouraging efficacy of ICIs, despite the high rate of irAEs. A deeper mechanism understanding at molecular level how ICIs function in TETs and why irAEs occur will help maximize the immunotherapeutic efficacy while minimizing irAEs risks in TET treatment to improve patient prognosis.

Exosomal circZNF451 restrains anti-PD1 treatment in lung adenocarcinoma via polarizing macrophages by complexing with TRIM56 and FXR1.

BACKGROUND: Although success was achieved in the therapy for a minority of advanced lung adenocarcinoma (LUAD) patients, anti-programmed death 1 (PD1) resistance was found in most LUAD patients. Here, we aimed to uncover a potential role of exosomal circular RNAs (circRNAs) in LUAD refractory to PD1 blockade.  METHODS: circRNA sequencing and qRT-PCR were performed to determine the level of exosomal circRNAs in LUAD patients subsequently treated with anti-PD1. Then, the RNA pulldown, RNA immunoprecipitation, mass spectrometry, chromatin immunoprecipitation, luciferase reporter assays, flow cytometry, RNA sequencing, and in vitro and in vivo models were used to uncover the biological functions and underlying mechanism of circZNF451 in LUAD anti-PD1 treatment resistance. RESULTS: circRNA sequencing and qRT-PCR identified the up-regulation of exosomal circZNF451 from LUAD patients with progressive disease (PD) compared to those with partial remission (PR) after PD1 blockade therapy. Furthermore, elevated circZNF451 was revealed to be associated with poor prognosis of LUAD patients. Additionally, exosomal circZNF451 was demonstrated to induce an anti-inflammatory phenotype in macrophages and exhaustion of cytotoxic CD8+ T cells, and enhanced TRIM56-mediated degradation of FXR1 to activate the ELF4-IRF4 pathway in macrophages. By transgenic mice, knockout of ELF4 in macrophages was found to rescue immunotherapy efficacy in tumors with high level of exosomal circZNF451. CONCLUSION: Exosomal circZNF451 reshapes the tumor immune microenvironment by inducing macrophages polarization via the FXR1- ELF4-IRF4 axis and is a novel biomarker for predicting the sensitivity of PD1 blockade in LUAD.

A novel predictive model for distinguishing mediastinal lymphomas from thymic epithelial tumours.

OBJECTIVES: We recently reported a high rate of nontherapeutic thymectomy. Mediastinal lymphomas (MLs) are the malignancies most likely to be confused with thymic epithelial tumours (TETs). This study aimed to establish a predictive model by evaluating clinical variables and positron emission tomography to distinguish those diseases. METHODS: From 2018 to 2021, consecutive patients who were pathologically diagnosed with TETs or MLs were retrospectively reviewed. Univariable and multivariable analyses were used to identify association factors. The Akaike information criterion was used to select variables. A nomogram was developed and validated to differentiate MLs from TETs. RESULTS: A total of 198 patients were included. Compared with TETs, patients with MLs were more likely to be younger with higher metabolic tumour volume (154.1 vs 74.6 cm3), total lesion glycolysis (1388.8 vs 315.2 g/ml cm3), SUVmean (9.2 vs 4.8), SUVpeak (12.9 vs 6.3) and SUVmax (14.8 vs 7.5). A nomogram was established based on the stepwise regression results and the final model containing age and SUVmax had minimal Akaike information criterion value of 72.28. Receiver operating characteristic analyses indicated that the area under the curve of predictive nomogram in differentiating MLs from TETs was 0.842 (95% CI: 0.754-0.907). The internal bootstrap resampling and calibration plots demonstrated good consistence between the prediction and the observation. CONCLUSIONS: Combination of age and SUVmax appears to be a useful tool to differentiate MLs from TETs. The novel predictive model prevents more patients from receiving nontherapeutic thymectomy.

Elevated circASCC3 limits antitumor immunity by sponging miR-432-5p to upregulate C5a in non-small cell lung cancer.

Although anti-programmed cell death 1 (PD1) treatment has become a first-line therapy for advanced non-small cell lung cancer (NSCLC), most NSCLC patients are refractory to anti-PD1. Here, we aimed to investigate the mechanism of dysregulated circular RNAs (circRNAs) related to anti-PD1 resistance in NSCLC. The expression of circASCC3 (hsa_circ_0077,495) in NSCLC tissues and cell lines was evaluated by fluorescence in situ hybridization and quantitative reverse transcription-polymerase chain reaction. The functions and mechanisms of circASCC3 in NSCLC progression and anti-PD1 resistance were uncovered in vitro and in vivo. The circASCC3 level was upregulated in NSCLC compared with that in paired normal tissues. Specifically, circASCC3 expression was higher in tissues from NSCLC patients with anti-PD1 refractory than in those from patients who sensitive to anti-PD1. Overexpression of circASCC3 enhanced the malignant phenotype of NSCLC cells and led to an immunosuppressive microenvironment. Mechanistically, circASCC3 sponged miR-432-5p to increase complement C5a levels, which enhanced the progression and dysfunctional immune status of NSCLC. Thus, circASCC3 overexpression reshapes the tumor microenvironment by impacting the complement system in NSCLC and provides a potential strategy to overcome anti-PD1 resistance.

How can the rate of nontherapeutic thymectomy be reduced?

OBJECTIVES: The aim of this study was to determine the prevalence of nontherapeutic thymectomy and define a clinical standard to reduce it. METHODS: From 2016 to 2020, consecutive patients who underwent thymectomy were retrospectively reviewed. Univariable and multivariable analyses were used to identify the correlation factors of nontherapeutic thymectomy. A receiver operating characteristic curve was analysed to assess the cut-off threshold of factors correlated with nontherapeutic thymectomy. RESULTS: A total of 1039 patients were included in this study. Overall, 78.4% (n = 814) of thymectomies were therapeutic and 21.6% (n = 225) were nontherapeutic. Thymoma (57.9%, n = 602) was the most common diagnosis in therapeutic thymectomy. Among those of nontherapeutic thymectomy, thymic cysts (11.9%, n = 124) were the most common lesion. Compared with therapeutic thymectomy, patients with nontherapeutic thymectomy were more likely to be younger (median age 50.1 vs 55.6 years, P < 0.001) with a smaller precontrast and postcontrast computed tomography (CT) value (P < 0.001, P < 0.001), as well as ΔCT value [10.7 vs 23.5 Hounsfield units (HU), P < 0.001]. Multivariable analysis indicated that only age and ΔCT value were significantly different between therapeutic and nontherapeutic thymectomy groups. Receiver operating characteristic curve analysis showed that cut-off values of age and ΔCT value were 44 years and 6 HU, respectively. Patients with age ≤44 years and a ΔCT value ≤6 HU had a 95% probability of nontherapeutic thymectomy. CONCLUSIONS: Surgeons should be cautious to perform thymectomy for patients with age ≤44 years and ΔCT value ≤6 HU. This simple clinical standard is helpful to reduce the rate of nontherapeutic thymectomy.

Recent thymic emigrants as the bridge between thymoma and autoimmune diseases.

Recent thymic emigrants (RTEs) are naïve T cells that egress the thymus following intrathymic development. This continuous process, including self-renewal, is crucial to establish and maintain human immune function. Several biomarkers can identify RTEs, but none of them is specific. Additional methods to detect and study RTEs phenotypically and functionally revealed alterations in RTEs in various adverse health conditions, including autoimmune diseases, systemic disorders and thymic abnormalities such as thymoma. Often associated with autoimmune disease, thymoma is the only tumor that can generate RTEs. However, a causal relationship between RTEs and autoimmune disease remains uncertain. Here, we review current knowledge about the connections between thymoma, RTEs and autoimmune diseases to provide new perspectives for therapeutic strategies.

Circulating tumor cell methylation profiles reveal the classification and evolution of non-small cell lung cancer.

Background: The ability of circulating tumor cells (CTCs) to identify lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) could improve pathological diagnosis and the selection of treatments for non-small cell lung cancer (NSCLC). Previous studies have shown that deoxyribonucleic acid (DNA) methylation exhibits cell and tissue specificity. Thus, we aimed to explore the methylation status of CTCs in LUAD and LUSC and identify the potential biomarkers. Methods: We first analyzed Infinium 450K methylation profiles obtained from The Cancer Genome Atlas and Gene Expression Omnibus. We then performed whole-genome sequencing of CTCs in tumor and matched normal lung tissues and white blood cells from 6 NSCLC patients. Results: The bioinformatics analysis revealed a NSCLC-specific DNA methylation marker panel, which could accurately distinguish between LUAD and LUSC with high diagnostic accuracy. The whole-genome sequencing of CTCs in NSCLC patients also showed 100% accuracy for distinguishing between LUAD and LUSC based on the CTC methylation profiles. To investigate the function of CTCs, we further analyzed similar and different methylation profiles between the CTCs and their primary tumors, and found very high similarities between the CTCs and their primary tumor tissues, indicating that these cells inherit information from primary tumors. However, the CTCs also displayed some characteristics that differed to those of primary tumor tissues, which suggest that CTCs acquire some unique characteristics after migrating from the primary tumor; these characteristics may partly explain the ability of tumor cells to evade immune surveillance. Conclusions: Our findings provide insights into the potential use of CTCs in the pathological classification of NSCLC patients. Our findings also show how CTC primary tumor inheritance and CTC evolution affect metastasis and immune escape.

Minimally invasive thymectomy for myasthenia gravis: a 7-year retrospective study.

BACKGROUND: Thymectomy has been identified as an effective strategy for patients with myasthenia gravis (MG) and thymic masses. However, the best surgical approach remains a matter of debate. The aim of the present study was to compare the surgical and neurological outcomes of video-assisted thoracoscopic thymectomy with a modified subxiphoid and bilateral approach in patients with MG and thymic masses. METHODS: From August 2013 to April 2018, 68 patients who were diagnosed with MG and thymic masses and underwent video-assisted thoracoscopic thymectomy with a modified subxiphoid (44 patients) or bilateral (24 patients) approach were included in this retrospective study. The surgical and neurological results were analyzed with propensity score matching. RESULTS: After propensity score matching, the modified subxiphoid approach in video-assisted thoracoscopic thymectomy resulted in an obviously shorter operative time (P=0.00), drainage duration (P=0.00), less intraoperative blood loss (P=0.00), and shorter postoperative hospital stay (P=0.01). In terms of neurological outcomes, no significant difference was observed in the improvement in MG, with 2-year complete stable remission rates of 21.1% and 26.3% (P=0.68) and 2-year pharmacological remission rates of 31.6% and 26.3% (P=0.60) for the bilateral and subxiphoid approaches, respectively. Additionally, the approaches resulted in similar effects on the magnitudes of decrease in the prednisolone and pyridostigmine doses after 2 years, with average pyridostigmine dose reductions of 72.2% and 71.1% (P=0.78) and average prednisolone reductions of 76.8% and 71.7% (P=0.96) for the bilateral and subxiphoid approaches, respectively. CONCLUSIONS: The modified subxiphoid approach was found to be superior to the bilateral approach in video-assisted thoracic surgery thymectomy in terms of the surgical outcomes and yielded similar neurological outcomes. Therefore, the modified subxiphoid approach is recommended as an alternative to the bilateral approach in the treatment of patients with MG and thymic masses.