Non-small cell lung cancer with loss of expression of the SWI/SNF complex is associated with aggressive clinicopathological features, PD-L1-positive status, and high tumor mutation burden

Clinical and pathological characteristics and prognostic factors of SMARCA4-deficient non-small cell lung cancer

The objective of the study is to investigate the clinicopathological features and prognostic factors of SMARCA4-deficient non-small cell lung cancer (SMARCA4-deficient NSCLC). A total of 43 patients with SMARCA4-deficient NSCLC who were diagnosed at Baotou Steel Hospital between January 2021 and October 2024 were included. Kaplan-Meier survival curves were plotted, and the log-rank test was used for group comparisons. Cox regression analysis was performed to identify factors influencing the 2-year overall survival in SMARCA4-deficient NSCLC patients. SMARCA4-deficient NSCLC patients exhibited distinct characteristics: older age (P < 0.05), male predominance (P < 0.05), smoking history (P < 0.05), larger tumors (P < 0.05), higher Ki-67 index (P < 0.05), lower EGFR mutation rates (P < 0.05), fewer squamous carcinomas (P < 0.05), and more poorly differentiated tumors (P < 0.05). Immunohistochemistry revealed BRG1 loss in 93.0 % (40/43), with TTF-1 (76.7 %) and P40 (81.4 %) negativity. The 2-year survival rate was significantly worse in SMARCA4-deficient NSCLC vs. SMARCA4-intact NSCLC (log-rank P < 0.001). Multivariate Cox analysis identified age ≥ 65 years (HR = 2.8, P = 0.003), smoking (HR = 2.4, P = 0.012), tumor size >5 cm (HR = 3.1, P < 0.001), and distant metastasis (HR = 4.5, P < 0.001) as independent predictors of poor survival in SMARCA4-deficient NSCLC. Patients with advanced-stage disease (III/IV) had significantly shorter survival (P < 0.05). SMARCA4 deficiency defines an aggressive NSCLC subtype with unique clinicopathological traits, including rapid progression, and poor survival.

SMARCA4-deficient non-small cell lung cancer with metastasis to the sigmoid colon: a case report

BACKGROUND

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4-deficient non-small cell lung cancer (SMARCA4-dNSCLC) is a rare subtype of NSCLC whose definitive radiographic characteristics have not yet been fully delineated. Clinically, these tumors often metastasize to distant organs and lymph nodes at an early stage, which is strongly associated with poor clinical prognosis. The common metastatic sites include bone, brain, adrenal glands, liver, and spleen, whereas intestinal metastasis is extremely rare. In this case, we describe a rare instance of SMARCA4-deficient NSCLC with metastasis to the sigmoid colon.

CASE DESCRIPTION

A 59-year-old male presented with hoarseness and shortness of breath. Computed tomography (CT) imaging revealed an irregular mass in the posterior apical segment of the upper lobe of the left lung, with enlarged lymph nodes in the mediastinum and left lung hilum. A biopsy of the lung mass confirmed the diagnosis of NSCLC with SMARCA4 gene deletion. CT also revealed uneven thickening of the sigmoid colon wall, which was proved to be metastases from the lung cancer through surgical pathology. The patient initially underwent chemotherapy combined with immunotherapy and intensity-modulated radiotherapy for the lungs. However, a follow-up CT revealed progression in the sigmoid colon tumor. Consequently, the patient underwent laparoscopic radical sigmoid colectomy with regional lymph node dissection. Two months postoperatively, metastasis to the left adrenal gland was detected. The treatment regimen was adjusted to a combination therapy consisting of gemcitabine, nedaplatin, bevacizumab, and camrelizumab accordingly. The patient demonstrated a favorable response to this treatment, with no evidence of recurrence or further metastasis to date.

CONCLUSIONS

This case represents the first reported instance of SMARCA4-dNSCLC with metastasis to the sigmoid colon. The atypical clinical and radiological features of this condition pose significant diagnostic challenges, particularly in differentiating metastatic lesions from primary colonic tumors. This case underscores the significance of recognizing rare metastatic patterns in SMARCA4-dNSCLC, enriching the literature on its diverse manifestations and providing a critical reference for clinicians in diagnosing and managing SMARCA4-dNSCLC with sigmoid colon metastasis.

Brain metastases lung adenocarcinoma patients with BRG1 loss have a grim prognosis, featuring unique morphological and methylation characteristics

BRG1 deficiency in patients with lung adenocarcinoma that has metastasized to the brain, termed BRG1-deficient brain metastasis lung adenocarcinoma, is an uncommon event. Prior to this study, these patients had not undergone extensive molecular and (epi)genetic analysis. We report a comprehensive clinical, histopathologic, and molecular assessment of 9 BRG1-deficient brain metastasis lung adenocarcinoma cohort (BRG1-deficient BM cohort) in comparison with a 16 BRG1-retained brain metastasis lung adenocarcinoma cohort (BRG1-retained BM cohort). Patients with BRG1-deficient BM exhibited a significantly increased risk of mortality. Molecular analysis revealed a high prevalence of mutations in SMARCA4 and TP53 genes within this group. DNA methylation molecular diagnostics showed a high rate of genomic instability and a markedly lower DNA methylation age in these patients. Functional enrichment analysis of differentially methylated genes suggested that hypomethylation genes were primarily associated with the negative regulation of neuron differentiation, G protein-coupled receptor signaling pathways, and cell differentiation. Conversely, hypermethylation was linked to the regulation of small GTPase mediated signal transduction, Rho protein signal transduction, DNA damage response, and apoptotic processes. This study investigated a rare subgroup of lung adenocarcinoma patients with brain metastasis characterized by BRG1 deficiency and a poor prognosis. Our study not only provides a comprehensive multi-omic data resource but also provides valuable biological insights into patients. The findings may serve as a valuable reference for the future pathological diagnosis of BRG1-deficient brain metastasis in lung adenocarcinoma patients.

Clinical characteristics and prognostic analysis of patients with SMARCA4-deficient lung cancer

BackgroundSMARCA4-deficient NSCLC is a rare type of tumor, accounting for approximately 10% of all NSCLC. It exhibits a weak response to conventional chemotherapy and has a poor prognosis, and lacks alterations in EGFR (epidermal growth factor receptor), ALK (anaplastic lymphoma kinase), and ROS1 (ROS proto-oncogene 1) genes Therefore, the mechanisms of SMARCA4 in NSCLC development urgently need to be explored to identify novel biomarkers and precise therapeutic strategies for this subtype.ObjectiveThe aim of this study was to understand the clinical characteristics of this special type of tumor and its response to different treatments.MethodsWe collected clinical data from 42 patients with SMARCA4-deficient NSCLC from July 2022 to January 2024, and analyzed their clinical features and survival state.ResultsThe study included a total of 42 patients diagnosed with NSCLC and harboring SMARCA4 mutation. The majority of these patients were male with a median age of 67 years. Most patients presented at stage IV upon diagnosis with highly aggressive tumors characterized by high Ki-67 proliferation index values resulting in poor overall prognosis. Genetic testing revealed TP53 gene mutations to be most prevalent (21%), followed by KRAS mutations (13%). Patients receiving immunotherapy exhibited significantly longer median overall survival compared to those treated solely with chemotherapy. Targeted drug therapy demonstrated favorable effects in some patients.ConclusionNSCLC patients harboring SMARCA4 deficiency exhibit poor overall survival rates with a median overall survival time of 5.4 months. Immunotherapy may provide benefits for NSCLC patients with SMARCA4 deficiency.

Cytotoxic mechanisms of pemetrexed and HDAC inhibition in non-small cell lung cancer cells involving ribonucleotides in DNA

The cytotoxic mechanisms of thymidylate synthase inhibitors, such as the multitarget antifolate pemetrexed, are not yet fully understood. Emerging evidence indicates that combining pemetrexed with histone deacetylase inhibitors (HDACi) may enhance therapeutic efficacy in non-small cell lung cancer (NSCLC). To explore this further, A549 NSCLC cells were treated with various combinations of pemetrexed and the HDACi MS275 (Entinostat), and subsequently assessed for cell viability, cell cycle changes, and genotoxic markers. Proteomic alterations were analyzed using label-free shotgun and targeted LC-MS/MS. MS275 enhanced the sensitivity of A549 cells to pemetrexed, but only when administered following prior treatment with pemetrexed. Both HeLa (p53 negative) and A549 (p53 positive) showed robust activation of γH2AX upon treatment with this combination. Importantly, CRISPR/Cas9 knockout of the uracil-DNA glycosylase UNG did not affect γH2AX activation or sensitivity to pemetrexed. Proteomic analysis revealed that MS275 altered the expression of known pemetrexed targets, as well as several proteins involved in pyrimidine metabolism and DNA repair, which could potentiate pemetrexed cytotoxicity. Contrary to the conventional model of antifolate toxicity, which implicates futile cycles of uracil incorporation and excision in DNA, we propose that ribonucleotide incorporation in nuclear and mitochondrial DNA significantly contributes to the cytotoxicity of antifolates like pemetrexed, and likely also of fluorinated pyrimidine analogs. HDAC inhibition apparently exacerbates cytotoxicity of these agents by inhibiting error-free repair of misincorporated ribonucleotides in DNA. The potential of HDACis to modulate pyrimidine metabolism and DNA damage responses offers novel strategies for improving NSCLC outcomes.

Predicting hepatocellular carcinoma outcomes and immune therapy response with ATP-dependent chromatin remodeling-related genes, highlighting MORF4L1 as a promising target

BACKGROUND

Hepatocellular carcinoma (HCC) continues to be a major cause of cancer-related death worldwide, primarily due to delays in diagnosis and resistance to existing treatments. Recent research has identified ATP-dependent chromatin remodeling-related genes (ACRRGs) as promising targets for therapeutic intervention across various types of cancer. This development offers potential new avenues for addressing the challenges in HCC management.

METHODS

This study integrated bioinformatics analyses and experimental approaches to explore the role of ACRRGs in HCC. We utilized data from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO), applying machine learning algorithms to develop a prognostic model based on ACRRGs' expression. Experimental validation was conducted using quantitative real-time Polymerase Chain Reaction (qRT-PCR), Western blotting, and functional assays in HCC cell lines and xenograft models.

RESULTS

Our bioinformatics analysis identified four key ACRRGs-MORF4L1, HDAC1, VPS72, and RUVBL2-that serve as prognostic markers for HCC. The developed risk prediction model effectively distinguished between high-risk and low-risk patients, showing significant differences in survival outcomes and predicting responses to immunotherapy in HCC patients. Experimentally, MORF4L1 was demonstrated to enhance cancer stemness by activating the Hedgehog signaling pathway, as supported by both in vitro and in vivo assays.

CONCLUSION

ACRRGs, particularly MORF4L1, play crucial roles in modulating HCC progression, offering new insights into the molecular mechanisms driving HCC and potential therapeutic targets. Our findings advocate for the inclusion of chromatin remodeling dynamics in the strategic development of precision therapies for HCC.

SMARCB1/INI-1-Deficient sinonasal carcinoma demonstrates a poor prognosis but favorable clinical outcomes after PD-1/PD-L1 inhibitor therapy: A case series

Despite advances in multimodal cancer therapy, such as combining radical surgery with high-intensity chemoradiotherapy, for SMARCB1/INI-1-deficient sinonasal carcinoma (SDSC), the prognosis of patients remains poor. Immunotherapy is gaining increasing popularity as a novel treatment strategy for patients with SMARCB1/INI-1-deficient tumors. Herein, we report on the management of three patients with SDSC who received PD-1/PD-L1 inhibitor therapy as a part of multimodal therapy based on surgery and chemoradiotherapy. All three patients survived and demonstrated good clinical remission and disease control. To our knowledge, this is the first case series reporting the use of immunotherapy to improve clinical outcomes in neoadjuvant, adjuvant, and late first-line stages of treatment in patients with SDSC. Furthermore, we reviewed the relevant literature and further explored the correlation between SMARCB1/INI-1 deletion and immunotherapy.

SMARCA4 Deficiency in Lung Cancer: From Signaling Pathway to Potential Therapeutic Targets

SMARCA4-deficient lung cancer, including thoracic SMARCA4-deficient undifferentiated tumors and SMARCA4-deficient nonsmall-cell lung carcinomas, is a rare and aggressive disease characterized by rapid progression and poor prognosis. This cancer was identified as a distinct entity with specific morphologic and molecular features in the 2021 WHO Classification of Thoracic Tumors. Molecular alterations in SMARCA4 are specific to this type of lung cancer. Deficiency in SMARCA4 suppresses the SWI/SNF tumor suppressor complex, driving tumor progression. Due to the lack of standardized treatment, most patients succumb to the disease within 6 months. This study provides a detailed analysis of the SMARCA4 pathway and its role in lung cancer. We analyzed potential therapeutic targets and agents to offer insights for the precise and effective treatment of SMARCA4-deficient lung cancer.

Case report: Aggressive NSCLC with partial BRG-1 deficiency and KRAS G12C mutation: a case study and treatment challenges

Background

SMARCA4-deficient (BRG-1 deficient) primary thoracic tumors are rare aggressive malignancies associated with poor prognosis. While complete BRG-1 loss is well-documented, the clinical implications of partial BRG-1 deficiency remain unclear. This case report explores a case of mixed lung cancer with partial BRG-1 deficiency and KRAS G12C mutation, highlighting its clinical relevance, treatment challenges, and the importance of comprehensive molecular profiling.

Methods

We performed immunohistochemistry, next-generation sequencing, and PD-L1 expression analysis to characterize the tumor. Treatment included surgical resection, chemotherapy, and immunotherapy.

Case presentation

We present a case of early-stage mixed lung cancer with partial BRG-1 deficiency in a 66-year-old male, treated with surgical resection, chemotherapy, and later, a PD-1 inhibitor. Despite aggressive treatment, rapid progression to brain metastasis was observed, underscoring the need for tailored approaches.

Conclusion

Partial BRG-1 deficiency may lead to aggressive clinical behavior, similar to complete BRG-1 loss. This case emphasizes the importance of comprehensive molecular profiling to guide treatment decisions and suggests further investigation into combined therapeutic strategies, including immunotherapy.

Concurrent EGFR mutation and SMARCA4 deficiency in non-small cell lung cancer: A case report and literature review

RATIONALE

SMARCA4-deficient non-small cell lung cancer (NSCLC) represents a highly aggressive subtype with poor prognosis. While clinical studies have identified common co-mutations in TP53, LRP1B, STK11, KEAP1, and KRAS, actionable driver mutations such as EGFR or ALK are rarely reported in conjunction with SMARCA4 deficiency. This case presents a rare instance of NSCLC featuring both an EGFR exon 21 L858R mutation and SMARCA4 deficiency, highlighting the challenges in treatment and the need for novel therapeutic strategies.

PATIENT CONCERNS

A 79-year-old female patient presented with concerns of a lung mass, suspected to be peripheral lung cancer based on diagnostic imaging.

DIAGNOSES

Histopathological evaluation confirmed SMARCA4-deficient NSCLC. Molecular genetic analysis further revealed an EGFR exon 21 L858R mutation.

INTERVENTIONS

The patient was initially treated with osimertinib, an EGFR tyrosine kinase inhibitor. Upon disease progression, treatment was adjusted to include anlotinib in combination with ongoing osimertinib.

OUTCOMES

The initial treatment with osimertinib led to partial remission. However, disease progression necessitated a change in therapy. The combination treatment stabilized the disease temporarily, achieving a stable disease status.

LESSONS

This case underscores the transient efficacy of targeted therapy in SMARCA4-deficient NSCLC with concurrent EGFR mutations. It highlights the need for continuous therapeutic adjustments and emphasizes the importance of further research into effective strategies for treating this complex and challenging subset of NSCLC, as current modalities have limitations in sustained efficacy.

SMARCA4 alterations in non-small cell lung cancer: a systematic review and meta-analysis

AIMS

A mutation in the SMARCA4 gene which encodes BRG1, a common catalytic subunit of switch/sucrose non-fermentable chromatin-remodelling complexes, plays a vital role in carcinogenesis. SMARCA4 mutations are present in approximately 10% of non-small cell lung cancers (NSCLC), making it a crucial gene in NSCLC, but with varying prognostic associations. To explore this, we conducted a systematic review and meta-analysis on the prognostic significance of SMARCA4 mutations in NSCLC.

METHODS

Electronic database search was performed from inception to December 2022. Study characteristics and prognostic data were extracted from each eligible study. Depending on heterogeneity, pooled HR and 95% CI were derived using the random-effects or fixed-effects models.

RESULTS

8 studies (11 cohorts) enrolling 8371 patients were eligible for inclusion. Data on overall survival (OS) and progression-free survival (PFS) were available from 8 (10 cohorts) and 1 (3 cohorts) studies, respectively. Comparing SMARCA4-mutated NSCLC patients with SMARCA4-wild-type NSCLC patients, the summary HRs for OS and PFS were 1.49 (95% CI 1.18 to 1.87; I2=84%) and 3.97 (95% CI 1.32 to 11.92; I2=79%), respectively. The results from the trim-and-fill method for publication bias and sensitivity analysis were inconsistent with the primary analyses. Three studies reported NSCLC prognosis for category I and II mutations separately; category I was significantly associated with OS.

CONCLUSION

Our findings suggest that SMARCA4 mutation negatively affects NSCLC OS and PFS. The prognostic effects of SMARCA4-co-occurring mutations and the predictive role of SMARCA4 mutation status in immunotherapy require further exploration.

SMARCA4 deficiency and mutations are frequent in large cell lung carcinoma and are prognostically significant

SMARCA4 mutation has emerged as a marker of poor prognosis in lung cancer and has potential predictive value in cancer treatment, but recommendations for which patients require its investigation are lacking. We comprehensively studied SMARCA4 alterations and the clinicopathological significance in a large cohort of immunohistochemically-subtyped non-small cell lung cancer (NSCLC). A total of 1416 patients was studied for the presence of SMARCA4 deficiency by immunohistochemistry (IHC). Thereafter, comprehensive sequencing of tumours was performed for 397 of these patients to study the mutational spectrum of SWI/SNF and SMARCA4 aberrations. IHC evidence of SMARCA4 deficiency was found in 2.9% of NSCLC. Of the sequenced tumours, 38.3% showed aberration in SWI/SNF complex, and 9.3% had SMARCA4 mutations. Strikingly, SMARCA4 aberrations were much more prevalent in large cell carcinoma (LCC) than other histological tumour subtypes. SMARCA4-deficient and SMARCA4-mutated tumours accounted for 40.5% and 51.4% of all LCC, respectively. Multivariable analyses confirmed SMARCA4 mutation was an independent prognostic factor in lung cancer. The immunophenotype of a subset of these tumours frequently showed TTF1 negativity and HepPAR1 positivity. SMARCA4 mutation or its deficiency was associated with positive smoking history and poor prognosis. It also demonstrated mutual exclusion with EGFR mutation. Taken together, the high incidence of SMARCA4 aberrations in LCC may indicate its diagnostic and prognostic value. Our study established the necessity of SMARCA4 IHC in the identification of SMARCA4-aberrant tumours, and this may be of particular importance in LCC and tumours without known driver events.

Rare SMARCA4-deficient thoracic tumor: Insights into molecular characterization and optimal therapeutics methods

INTRODUCTIONS

The 2021 WHO Classification of Thoracic Tumors recognized SMARCA4-deficient undifferentiated thoracic tumors (SMARCA4-dUT) as a distinct entity that shows a striking overlap in demographic and molecular profiles with SMARCA4-deficient non-small lung cancer (SMARCA4-dNSCLC). The implications of SMARCA4 deficiency based on immunohistochemistry remain unclear. We aimed to investigate molecular characteristics of SMARCA4-deficient thoracic tumors (SDTT) and explore optimal therapeutics.

METHODS

From June.15, 2018, to Nov.15, 2023, a large cohort including patients diagnosed with SMARCA4-deficient (N = 196) and SMARCA4-intact (N = 438) thoracic tumors confirmed by immunohistochemistry at SYSUCC were screened. Clinicopathologic and molecular characteristics were identified and compared. External SRRSH cohort (N = 34) was combined into a pooled cohort to compare clinical outcome of first-line therapy efficacy.

RESULTS

SDTT is male predominance with smoking history, high tumor burden, and adrenal metastases. The relationship between SMARCA4 mutation and protein expression is not completely parallel. The majority of SMARCA4-deficient patients harbor truncating (Class-I) SMARCA4 mutations, whereas class-II alterations and wild-type also exist. Compared with SMARCA4-intact thoracic tumors, patients with SDTT displayed a higher tumor mutation burden (TMB) and associated with a shorter median OS (16.8 months vs. Not reached; P < 0.001). Notably, SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in these differences. SDTT is generally resistant to chemotherapy, while sensitive to chemoimmunotherapy (median PFS: 7.5 vs. 3.5 months, P < 0.001). In particular, patients with SMARCA4 deficient thoracic tumors treated with paclitaxel-based chemoimmunotherapy achieved a longer median PFS than those with pemetrexed-based chemoimmunotherapy (10.0 vs. 7.3 months, P = 0.028).

CONCLUSIONS

SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in its characteristics of higher TMB and poor prognosis. Chemoimmunotherapy serves as the optimal option in the current treatment regimen. Paclitaxel-based chemoimmunotherapy performed better than those with pemetrexed-based chemoimmunotherapy.

Thoracic SMARCA4-deficient undifferentiated tumor: current knowledge and future perspectives

Thoracic SMARCA4-deficient undifferentiated tumor is a newly recognized disease entity characterized as a high-grade malignant neoplasm with an undifferentiated or rhabdoid phenotype. The tumor was initially identified as a subtype of thoracic sarcoma with SMARCA4 loss, but further investigation resulted in its classification as a subtype of epithelial malignancies in the current World Health Organization classification. SMARCA4-deficient undifferentiated tumor is highly aggressive and has a poor prognosis. Because of its rarity, an optimal treatment strategy has not yet been identified. In this review, we summarize the literature on SMARCA4-deficient undifferentiated tumor in terms of its clinical characteristics, diagnosis, treatment strategy and future perspectives.

Thoracic SMARCA4-deficient undifferentiated tumor: A clinicopathological and prognostic analysis of 35 cases and immunotherapy efficacy

BACKGROUND

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently recognized distinct clinicopathological entity according to the fifth edition of the 2021 World Health Organization Classification (WHO) for thoracic tumors. Thoracic SMARCA4-UTs are diagnostically challenging to diagnose, especially on small biopsies.

METHODS

We identified 35 thoracic SMARCA4-UTs from the Department of Pathology of West China Hospital, Sichuan University, between January 2017 and December 2022. In the present study, we summarized the clinicopathological features, prognostic significance and immunotherapy efficacy of thoracic SMARCA4-UTs.

RESULTS

All 35 patients were male, and 88.6 % were smokers. The left upper lobe (25.7 %) and mediastinum (20.0 %) were the most affected sites. 17.1 % of the patients received surgical treatment. 30.4 % of the patients were stage III, and 69.6 % were stage IV. Solid architecture (100 %), rhabdoid morphology (51.4 %) and necrosis (42.9 %) were the common histological features. Immunohistochemical staining revealed CD34 and synaptophysin positivity in most patients (76.9 % and 65.2 %, respectively). Patients had unfavorable outcomes. Patients who received immunotherapy had better OS and PFS than those who did not (p = 0.007 and p = 0.02, respectively). Five patients were evaluated for immunotherapy efficacy, and four of those patients were negative expression of PD-L1. Cases 1-4 presented TIL counts ranging from 20 to 1000/HPF. Case 5 presented TIL counts of 5-10/HPF. Mutations in SMARCA4 were confirmed in cases 4 and 5, and the TMB was 5.98 and 5.03 mutations/Mb, respectively. Case 1 achieved a CR, cases 2-4 achieved a PR, and case 5 had a PD. Five patients who received immunotherapy were all alive, with OS ranging from 10.7 to 33.6 months.

CONCLUSIONS

Thoracic SMARCA4-UTs exhibited an aggressive clinical course, presented solid architecture with or without necrosis and/or rhabdoid morphology, and frequently expressed CD34 and synaptophysin. Some thoracic SMARCA4-UTs appear to be associated with responsiveness to immunotherapy, suggesting the need for validation in larger series.

Unveiling the role of KRAS in tumor immune microenvironment

Kirsten rats sarcoma viral oncogene (KRAS), the first discovered human oncogene, has long been recognized as "undruggable". KRAS mutations frequently occur in multiple human cancers including non-small cell lung cancer(NSCLC), colorectal cancer(CRC) and pancreatic ductal adenocarcinoma(PDAC), functioning as a "molecule switch" determining the activation of various oncogenic signaling pathways. Except for its intrinsic pro-tumorigenic role, KRAS alteration also exhibits an unique immune signature characterized by elevated PD-L1 level and high tumor mutational burden(TMB). KRAS mutation shape an immune suppressive microenvironment by impeding effective T cells infiltration and recruiting suppressive immune cells including myeloid-derived suppressor cells(MDSCs), regulatory T cells(Tregs), cancer associated fibroblasts(CAFs). In immune checkpoint inhibitor(ICI) era, NSCLC patients with mutated KRAS tend to be more responsive to ICI than patients with intact KRAS. The hallmark for KRAS mutation is the existence of multiple kinds of co-mutations. Different types of co-alterations have distinct tumor microenvironment(TME) signatures and responses to ICI. TP53 co-mutation possess a "hot" TME and achieve higher response to immunotherapy while other loss of function mutation correlated with a "colder" TME and a poor outcome to ICI-based therapy. The groundbreaking discovery of KRAS G12C inhibitors significantly improved outcomes for this KRAS subtype even though efficacy was limited to NSCLC patients. KRAS G12C inhibitors also restore the suppressive TME, creating an opportunity for combinations with ICI. However, an inevitable challenge to KRAS inhibitors is drug resistance. Promising combination strategies such as combination with SHP2 is an approach deserve further exploration because of their immune modulatory effect.

Response to PD-1 inhibitor in SMARCB1‑deficient undifferentiated rectal carcinoma with low TMB, proficient MMR and BRAF V600E mutation: a case report and literature review

BACKGROUND

Despite major advancements, effective treatment for patients with SMARCB1-deficient cancers has remained elusive. Here, we report the first case of a SMARCB1-deficient undifferentiated carcinoma in the rectum expressing high PD-L1 and responding to a PD-1 inhibitor, as well as with low tumor mutation burden (TMB), proficient mismatch repair (MMR) and BRAF V600E mutation.

CASE PRESENTATION

A 35-year-old man visited our hospital complaining of increased defecation frequency, bloody stools and weight loss of 3 kg for one month. Colonoscopy revealed an ulcerated and irregular mass approximately 8-12 cm from the anus. Surgical resection was performed. Histopathological findings revealed that the tumor cells had poor connectivity with each other; each cell had eosinophilic cytoplasm and a polymorphic nucleus. Brisk mitotic activity and necrosis were frequently observed in the tumor cells. Immunohistochemical examination showed that the tumor cells were negative for SMARCB1. The tumor proportion score (TPS) of PD-L1 (22C3) expression was 95%, and the combined positive score (CPS) was 100; the tumor was mismatch repair (MMR) proficient. Next-generation sequencing showed a low tumor mutation burden (TMB), as well as the BRAF V600E mutation. The final diagnosis was SMARCB1-deficient undifferentiated carcinoma. Chemotherapy was useless in this case. His tumor recurred during chemotherapy, and he then received targeted therapy with tirelizumab, an inhibitor of PD-1. At present, his general condition is good. A recent computed tomography (CT) scan showed that the tumor had disappeared, indicating that the immunotherapy was effective. Astonishingly, his most recent follow-up was in August, and his condition continued to improve with the tumor has disappeared.

CONCLUSION

SMARCB1‑deficient undifferentiated carcinoma in the rectum is extremely rare, and it has aggressive histological malignancy and poor progression. The observed response to PD-1 inhibitors suggests a role for prospective use of SMARCB1 alterations as a predictive marker for immune checkpoint blockade.

Clinicopathological characteristics and treatment outcomes of advanced SMARCA4-deficient thoracic tumors

PURPOSE

SMARCA4-deficient thoracic tumors, characterized by distinct clinicopathological, morphological, immunohistochemical, and genetic features, differ significantly from conventional non-small-cell lung carcinomas (NSCLCs). This group encompasses both SMARCA4-deficient NSCLCs (SMARCA4-NSCLCs) and SMARCA4-deficient undifferentiated tumors (SMARCA4-UTs). The efficacy of PD-1 inhibitors in treating SMARCA4-deficient thoracic tumors remains uncertain.

METHODS

Medical records of 36 patients diagnosed with stage IIIB, IIIC, or IV SMARCA4-deficient thoracic tumors were analyzed. We assessed the clinical, pathological, and genetic features of these patients through immunohistochemistry (IHC) and a 68-gene panel next-generation sequencing (NGS). We compared the differences between SMARCA4-NSCLCs and SMARCA4-UTs, and evaluated the impact of chemotherapy and immunotherapy on patient outcomes.

RESULTS

The majority of patients with SMARCA4-deficient thoracic tumors were heavy-smoking males, averaging 64.6 years in age. IHC predominantly showed weak or negative staining for markers such as TTF-1, CK5/6, p40, synaptophysin, chromogranin A, and CD56, which are often associated with adenocarcinoma, squamous cell carcinoma, and neuroendocrine tumors. The most common genetic mutations identified via NGS included TP53, CDKN2A, KRAS, STK11, NF1, and PTEN. No significant overall survival (OS) difference was observed between SMARCA4-NSCLCs and SMARCA4-UTs (p = 0.366). The median OS for patients treated with chemotherapy (n = 9) was 447 days, while the median OS for patients undergoing PD-1-inhibitor-based therapy (n = 16) was not reached (p = 0.105).

CONCLUSION

SMARCA4-deficient thoracic tumors exhibit distinct characteristics from conventional NSCLCs, and PD-1 inhibitors show promise in treating advanced SMARCA4-deficient thoracic tumors.

The Role of the AT-Rich Interaction Domain 1A Gene (ARID1A) in Human Carcinogenesis

The switch/sucrose non-fermentable (SWI/SNF) (SWI/SNF) complex uses energy from ATP hydrolysis to mobilise nucleosomes on chromatin. Components of SWI/SNF are mutated in 20% of all human cancers, of which mutations in AT-rich binding domain protein 1A (ARID1A) are the most common. ARID1A is mutated in nearly half of ovarian clear cell carcinoma and around one-third of endometrial and ovarian carcinomas of the endometrioid type. This review will examine in detail the molecular functions of ARID1A, including its role in cell cycle control, enhancer regulation, and the prevention of telomerase activity. ARID1A has key roles in the maintenance of genomic integrity, including DNA double-stranded break repair, DNA decatenation, integrity of the cohesin complex, and reduction in replication stress, and is also involved in mismatch repair. The role of ARID1A loss in the pathogenesis of some of the most common human cancers is discussed, with a particular emphasis on gynaecological cancers. Finally, several promising synthetic lethal strategies, which exploit the specific vulnerabilities of ARID1A-deficient cancer cells, are briefly mentioned.

SMARCA4‑deficient non‑small cell lung cancer with an EGFR mutation: A case report

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4 (SMARCA4)-deficient non-small cell lung cancer (dNSCLC) is a rare malignant tumor that originates in the lungs. It occurs more frequently in male smokers, and the epidermal growth factor receptor (EGFR) gene is often mutation-free. In the present study, the case of a 60-year-old, non-smoking female patient diagnosed with SMARCA4-dNSCLC is reported. Biopsy of the tumor showed solid flaky, nest-like infiltrating growth. Immunohistochemistry revealed the following: SMARCA4/BRG1(-), SMARCB1/INI-1(+), cytokeratin7 (+), cytokeratin 5.2 (+), CK5/6(+) and calretinin(+). The Ki-67 positivity index was 75%, and the thyroid transcription factor-1, NapsinA, p40, nuclear protein in testis, CD34, Sal-like protein 4, SRY-box transcription factor 2 and synaptophysin were negative. Molecular analysis showed mutations in both EGFR and TP53. The pathological diagnosis was SMARCA4-dNSCLC with an EGFR gene mutation. The present case report could be used for broadening the pathological diagnosis of SMARCA4-dNSCLC and for selecting appropriate treatment approaches.

The clinicopathological features of BRG1-deficient non-small cell lung cancer and its response to immunotherapy: A single-center retrospective study

PURPOSE

BRG1-deficient NSCLCs have been more intriguing recently for its highly aggressive clinical behavior and no effective therapies. This study characterized the clinical and pathological features of BRG1-deficient NSCLCs and investigated their response to immunotherapy.

METHODS

Forty-seven cases with BRG1-deficient NSCLC were included. Immunohistochemical markers such as BRG1, CK7, TTF-1, NapsinA, P40, HepPar-1, Ki-67, BRM, ARID1A and ARID1B were stained. Additionally, the PD-L1 expression level, overall survival, progression-free survival and disease control rate of patients received immunotherapy were evaluated.

RESULTS

This study revealed that: (1) Patients with BRG1-deficient NSCLC have a male predominance (89.4 %), smoker enrichment (76.6 %) and poor prognosis (median OS: 7.0 months for advanced stage). (2) Histologically, BRG1-deficient NSCLCs presented significant morphological diversity and no lepidic pattern. Inflammatory infiltration and tumor necrosis was a prominent feature. Immunohistochemical analyses showed a distinctive uniform immunophenotype (TTF-1-/NapsinA-/CK7+) in 60.9 % (28/46) of cases and HepPar-1 positive in 46.5 % (20/43) of cases. BRM loss or significant reduction coexisted in 11.8 % (4/34) of cases. No case (0/37) showed loss of ARID1A or ARID1B. (3) Eight patients with advanced tumor stage had received immunotherapy and 4 cases achieved a sustainable clinical response with the disease control rate of 50 %.

CONCLUSION

BRG1-deficient NSCLC showed diverse histopathological patterns and a unique immunohistochemical phenotype. ICIs-based immunotherapy is a promising therapy needs to be investigated further for BRG1- deficient NSCLC.

Molecular, clinicopathological characteristics and surgical results of resectable SMARCA4-deficient thoracic tumors

PURPOSE

SMARCA4-deficient thoracic tumors are rapid aggressive malignancies, often diagnosed at an advanced and inoperable stage. The value of pulmonary resection for resectable SMARCA4-deficient thoracic tumors is largely unknown.

METHODS

In this observational study, we included 45 patients who received surgery for stage I-III SMARCA4-deficient tumors. We compared the molecular, clinicopathological characteristics and survival between SMARCA4-dNSCLC and SMARCA4-deficient undifferentiated tumor (SMARCA4-dUT) patients.

RESULTS

Thirty-four SMARCA4-dNSCLC and 11 SMARCA4-dUT patients were included in this study. Molecular profiles were available in 33 out of 45 patients. The most common mutated gene was TP53 (21, 64%), and followed by STK11 (9, 27%), KRAS (5, 15%), FGFR1 (4, 12%) and ROS1 (4, 12%). There were 3 patients that harbored ALK mutation including 1 EML4-ALK rearrangement. There were 2 patients that harbored EGFR rare site missense mutation. SMARCA4-dUT patients had significance worse TTP (HR = 4.35 95% CI 1.77-10.71, p = 0.001) and OS (HR = 4.27, 95% CI 1.12-16.35, p = 0.022) compared to SMARCA4-dNSCLC patients. SMARCA4-dUT histologic type, stage II/III, R1/2 resection and lymphovascular invasion were independent poor prognostic predictors for both TTP and OS. There were 8 patients who received immunotherapy, the objective response rate was 50%. The SMARCA4-dNSCLC patient with ALK rearrangement was treated with crizotinib as second-line therapy, and achieved stable disease for 9.7 months.

CONCLUSION

Patients with SMARCA4-deficient tumors have a high probability of early recurrence after surgery, except for stage I patients. Immunotherapy seems to be a valuable strategy to treat recurrence.

Dysregulation of SWI/SNF Chromatin Remodelers in NSCLC: Its Influence on Cancer Therapies including Immunotherapy

Lung cancer is the leading cause of cancer death worldwide. Molecularly targeted therapeutics and immunotherapy revolutionized the clinical care of NSCLC patients. However, not all NSCLC patients harbor molecular targets (e.g., mutated EGFR), and only a subset benefits from immunotherapy. Moreover, we are lacking reliable biomarkers for immunotherapy, although PD-L1 expression has been mainly used for guiding front-line therapeutic options. Alterations of the SWI/SNF chromatin remodeler occur commonly in patients with NSCLC. This subset of NSCLC tumors tends to be undifferentiated and presents high heterogeneity in histology, and it shows a dismal prognosis because of poor response to the current standard therapies. Catalytic subunits SMARCA4/A2 and DNA binding subunits ARID1A/ARID1B/ARID2 as well as PBRM1 were identified to be the most commonly mutated subunits of SWI/SNF complexes in NSCLC. Mechanistically, alteration of these SWI/SNF subunits contributes to the tumorigenesis of NSCLC through compromising the function of critical tumor suppressor genes, enhancing oncogenic activity as well as impaired DNA repair capacity related to genomic instability. Several vulnerabilities of NSCLCS with altered SWI/SNF subunits were detected and evaluated clinically using EZH2 inhibitors, PROTACs of mutual synthetic lethal paralogs of the SWI/SNF subunits as well as PARP inhibitors. The response of NSCLC tumors with an alteration of SWI/SNF to ICIs might be confounded by the coexistence of mutations in genes capable of influencing patients' response to ICIs. High heterogenicity in the tumor with SWI/SNF deficiency might also be responsible for the seemingly conflicting results of ICI treatment of NSCLC patients with alterations of SWI/SNF. In addition, an alteration of each different SWI/SNF subunit might have a unique impact on the response of NSCLC with deficient SWI/SNF subunits. Prospective studies are required to evaluate how the alterations of the SWI/SNF in the subset of NSCLC patients impact the response to ICI treatment. Finally, it is worthwhile to point out that combining inhibitors of other chromatin modulators with ICIs has been proven to be effective for the treatment of NSCLC with deficient SWI/SNF chromatin remodelers.

Dynamic and Static 18F-FDG PET/CT Imaging in SMARCA4-Deficient Non-Small Cell Lung Cancer and Response to Therapy: A Case Report

SMARCA4-deficient non-small cell lung cancer (NSCLC) is a more recently recognized subset of NSCLC. We describe the ¹⁸F-fluorodeoxyglucose (FDG) PET/CT findings in a rare case of SMARCA4-deficient NSCLC and response to therapy. A 45-year-old male patient with a history of heavy smoking (10 years) underwent an ¹⁸F-fluorodeoxyglucose (FDG) PET/CT dynamic (chest) + static (whole-body) scan for diagnosis and pre-treatment staging. ¹⁸F-FDG PET/CT showed an FDG-avid mass in the upper lobe of the left lung (SUV_max of 22.4) and FDG-avid lymph nodes (LN) in the left pulmonary hilar region (SUV_max of 5.7). In addition, there were multiple metastases throughout the body, including in the distant LNs, adrenal glands, bone, left subcutaneous lumbar region, and brain. Pathological findings confirmed SMARCA4-deficient NSCLC. After four cycles of chemotherapy and immune checkpoint inhibitors (ICI), the patient underwent again an ¹⁸F-FDG PET/CT scan (including a dynamic scan) for efficacy evaluation. We report a case that deepens the understanding of the ¹⁸F-FDG PET/CT presentation of SMARCA4-deficient NSCLC as well as dynamic imaging features and parametric characteristics.

SMARCA4 as a support for the differential diagnosis of poorly differentiated lung carcinomas

Among non-small cell lung cancers (NSCLCs), sarcomatoid carcinomas account for 3%. They are rare tumours with a poor prognosis, classified into three subgroups, namely pleomorphic carcinoma, pulmonary blastoma and carcinosarcoma. In the 5th edition of WHO Classification of Thoracic Tumours more space is given to SMARC4-deficient lung cancers. Although studies on SMARCA4-deficient lung tumours are limited, a small percentage of SMARCA4 loss is present within NSCLCs. This finding is clinically relevant, as the loss of the SMARCA4 gene is associated with a worse prognosis. In our study, we analysed the presence of the main catalytic subunit of the SMARCA4 gene, the BRG1 protein, in 60 sarcomatoid lung tumours. The results of our study show that 5.3% of sarcomatoid carcinomas have BRG1-loss in tumour cells, proving that a non-negligible amount of lung sarcomatoid carcinomas are SMARCA4-deficient. These data open the debate on the necessity of including the detection of SMARCA4 within a standardised immunohistochemical panel.

Clinical characteristics and prognostic analysis of SMARCA4-deficient non-small cell lung cancer

PURPOSE

To improve the understanding of special types of tumors, we summarized and analyzed the clinicopathological features and prognostic factors of SMARCA4-deficient non-small cell lung cancer (SMARCA4-dNSCLC).

METHODS

We selected 105 patients with SMARCA4-dNSCLC and 221 patients with SMARCA4-intact non-small cell lung cancer (SMARCA4-iNSCLC) by performing immunohistochemical analysis of 1520 NSCLC samples, and we assessed the patients' clinicopathological features and survival state.

RESULTS

(1) SMARCA4-dNSCLC was significantly associated with older age, male sex, smoking history, larger invasive tumor size, higher tumor proliferation index (Ki-67), more adrenal metastases, more lymph node metastases, and few EGFR mutations (p < 0.05). The tumors were mostly negative for thyroid transcription factor-1 (TTF-1), CD34, and p40 and positive for cytokeratin 7 (CK7) in immunohistochemistry (IHC). Nineteen SMARCA4-dNSCLC patients mostly had TP53, SMARCA4, and LRP1B mutations, and 48% of them had SMARCA4 frameshift mutations. SMARCA4-dNSCLC patients have a worse prognosis than SMARCA4-iNSCLC patients (HR: 0.27; 95% CI: 0.17-0.45). The overall survival (OS) of patients with stage III SMARCA4-dNSCLC was worse than that of patients with SMARCA4-iNSCLC, and the OS of stage IV SMARCA4-dNSCLC patients was also worse than that of SMARCA4-iNSCLC patients (p < 0.01). (2) Multivariate regression analysis showed that sex (HR: 4.12; 95% CI: 1.03-16.39) and smoking history (HR: 2.29; 95% CI: 1.04-5.02) had significant effects on the survival time of SMARCA4-dNSCLC patients. In SMARCA4-dNSCLC patients without distant metastases (stage I-III), patients with stage N2 or N3 lymph node metastases (HR: 6.35; 95% CI: 1.07-37.47) had a poor prognosis. Among patients with SMARCA4-dNSCLC who were treated and had distant metastases (stage IV), male patients and patients treated with immunotherapy combined with chemotherapy showed a longer median overall survival (mOS).

CONCLUSION

SMARCA4-dNSCLC has unique clinicopathological features and a shorter survival prognosis than SMARCA4-iNSCLC. The efficacy of immunotherapy combined with chemotherapy needs to be observed for longer periods.

Two Cases of SMARCA4-Deficient Non-small Cell Lung Cancer (NSCLC) with Improved Performance Status (PS) after Treatment with Immune Checkpoint Inhibitors (ICIs)

SWItch/Sucrose Non-Fermentable (SWI/SNF)-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4 (SMARCA4) mutations are commonly reported in non-small cell lung cancer (NSCLC) and are associated with a poor prognosis. There is insufficient evidence regarding the efficacy of immune checkpoint inhibitors (ICIs) in SMARCA4-deficient NSCLC patients with poor performance status (PS). We report two cases of advanced SMARCA4-deficient NSCLC treated with ICIs, in which marked regression of the tumor and improved general condition of the patients were achieved.

Case report: Heterogenous SMARCA4-deficient thoracic non-small cell lung carcinoma with various responses to nivolumab

SMARCA4-deficient non-small cell carcinoma is an aggressive neoplasm with poor outcome. Several studies have highlighted its immunochemistry, pathophysiology, and underlying mechanisms, but studies of its definite treatment are few. Here, we report on a 69-year-old male with heterogenous pathological presentations of SMARCA4-deficient non-small cell carcinoma. He initially presented with neck lymphadenopathies. Immunohistochemistry staining and genomic profiling confirmed the diagnosis of SMARCA4-deficient non-small cell carcinoma. The patient responded well to immune checkpoint inhibitors with nivolumab. However, new lesions with various pathological presentations and various responses to nivolumab appeared during the treatment course. The patient survived more than 3 years from the initial diagnosis. This case shows the efficacy of nivolumab to treat SMARCA4-deficient non-small cell lung carcinoma.

SMARCA4 and SMARCE1 in gastric cancer: Correlation with ARID1A, and microsatellite stability, and SMARCE1/ERBB2 co-amplification

BACKGROUND

Recent studies have shown an association between certain subunits of the SWI/SNF complex with specific tumor characteristics in gastric cancer (GC). In an earlier study, we applied multiregional whole exome sequencing on multiple primary tumor samples and found alterations of the SWI/SNF complex in 78% of the cases. ERBB2, which encodes for Her2/neu, is a well-known predictive biomarker used to guide the treatment of GC in the palliative setting. SMARCE1, which encodes for a subunit of the SWI/SNF complex, is localized in close genetic proximity to ERBB2.

AIM

As little is known about the significance of the SWI/SNF complex in GC biology and the potential relationship between ERBB2 and SMARCE1 upregulation, we examined the expression patterns of SMARCA4 and SMARCE1, two mutually exclusive catalytic ATPase subunits of the SWI/SNF complex, in a well characterized GC cohort.

MATERIALS AND METHODS

The expression of SMARCA4 and SMARCE1 was studied by immunohistochemistry in connection with clinicopathological patient characteristics in a cohort of 468 GCs. Digital droplet polymerase chain reaction was performed for amplification analysis on ERBB2 and SMARCE1.

RESULTS

Immunohistochemical staining of whole-mount tissue sections found a diffusely "gray scale" expression of SMARCA4 in 446 (95.2%) GCs and of SMARCE1 in 463 (98.8%) GCs. The expression of SMARCA4 and SMARCE1 correlated significantly with ARID1A, p53, and microsatellite status. No correlation was found with the patient prognosis. The amplification analysis of SMARCE1 showed amplification in 4 of 34 cases. In 3 of 34 cases, SMARCE1 was co-amplified with ERBB2. We also found a co-expression of SMARCE1 and Her2/neu in a subset of patients.

CONCLUSION

While the effect of a co-amplification is currently unknown, synergistic effects of SMARCE1 and Her2/neu overexpression should be explored in future studies, holding potential for an improved treatment of GC.

SMARCA4: Current status and future perspectives in non-small-cell lung cancer

SMARCA4, also known as transcription activator, is an ATP-dependent catalytic subunit of SWI/SNF (SWItch/Sucrose NonFermentable) chromatin-remodeling complexes that participates in the regulation of chromatin structure and gene expression by supplying energy. As a tumor suppressor that has aberrant expression in ∼10% of non-small-cell lung cancers (NSCLCs), SMARCA4 possesses many biological functions, including regulating gene expression, differentiation and transcription. Furthermore, NSCLC patients with SMARCA4 alterations have a weak response to conventional chemotherapy and poor prognosis. Therefore, the mechanisms of SMARCA4 in NSCLC development urgently need to be explored to identify novel biomarkers and precise therapeutic strategies for this subtype. This review systematically describes the biological functions of SMARCA4 and its role in NSCLC development, metastasis, functional epigenetics and potential therapeutic approaches for NSCLCs with SMARCA4 alterations. Additionally, this paper explores the relationship and regulatory mechanisms shared by SMARCA4 and its mutually exclusive catalytic subunit SMARCA2. We aim to provide innovative treatment strategies and improve clinical outcomes for NSCLC patients with SMARCA4 alterations.

Review the progression of ovarian clear cell carcinoma from the perspective of genomics and epigenomics

Ovarian clear cell carcinoma (OCCC) is a rare subtype of epithelial ovarian cancer with unique molecular characteristics, specific biological and clinical behavior, poor prognosis and high resistance to chemotherapy. Pushed by the development of genome-wide technologies, our knowledge about the molecular features of OCCC has been considerably advanced. Numerous studies are emerging as groundbreaking, and many of them are promising treatment strategies. In this article, we reviewed studies about the genomics and epigenetics of OCCC, including gene mutation, copy number variations, DNA methylation and histone modifications.

Correlations of switch/sucrose nonfermentable complex mutations with clinical outcomes in advanced non-small cell lung cancer

BACKGROUND

The switch/sucrose nonfermentable complex mutations (SWI/SNF-mut) are common in non-small cell lung cancer (NSCLC). However, the association of SWI/SNF-mut with the clinical outcomes of immune checkpoint inhibitors (ICIs), particularly of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), has not been established.

METHODS

We retrospectively collected data of patients at Cancer Hospital Chinese Academy of Medical Sciences. Patients with advanced NSCLC who received programmed cell death protein-1 or programmed cell death ligand 1 (PD-[L]1) inhibitors were included in cohort 1 and those with EGFR mutations (EGFR-mutant) received EGFR-TKIs monotherapy were included in cohort 2. Two reported Memorial Sloan-Kettering Cancer Center (MSKCC) cohorts received immunotherapy alone used as the validation for cohort 1. We analyzed the relationship between SWI/SNF alterations and clinical outcomes in each cohort.

RESULTS

In total, 1162 patients were included, of which 230 patients (19.8%) were identified as SWI/SNF-mut with the most common genetic alterations being ARID1A (33.4%) and SMARCA4 (28.3%). In cohort 1 (n = 146), patients with co-mutations of SWI/SNF and Kirsten rat sarcoma oncogene (KRAS) (SWI/SNFmutKRASmut, n = 18) had significantly prolonged progression-free survival (PFS) (8.6 m vs. 1.9 m; hazard ratio [HR],  0.31; 95% confidence intervals [CI], 0.11-0.83; p = 0.032) to PD-(L)1 inhibitors monotherapy, which was consistent with the MSKCC cohorts (not reach [NR] vs. 6.3 m; HR, 0.36, 95% CI, 0.15-0.82; p = 0.016). In cohort 2 (n = 205), ARID1A-mut (n = 16) was associated with improved PFS after EGFR-TKIs (20.6 m vs. 11.2 m; HR, 0.47, 95% CI, 0.27-0.94; p = 0.023).

CONCLUSIONS

In advanced NSCLC, patients with SWI/SNFmutKRASmut seem to benefit more from ICIs. Furthermore, ARID1A-mut may provide a protective effect to EGFR-TKIs in EGFR-mutant patients. However, this is a retrospective single-institution analysis that requires further validation by large prospective studies.

ARID1A deficiency reverses the response to anti-PD(L)1 therapy in EGFR-mutant lung adenocarcinoma by enhancing autophagy-inhibited type I interferon production

INTRODUCTION

EGFR mutations in non-small cell lung cancer (NSCLC) are associated with a poor response to immune checkpoint inhibitors (ICIs), and only 20% of NSCLC patients harboring EGFR mutations benefit from immunotherapy. Novel biomarkers or therapeutics are needed to predict NSCLC prognosis and enhance the efficacy of ICIs in NSCLC patients harboring EGFR mutations, especially lung adenocarcinoma (LUAD) patients, who account for approximately 40-50% of all NSCLC cases.

METHODS

An ARID1A-knockdown (ARID1A-KD) EGFR-mutant LUAD cell line was constructed using lentivirus. RNA-seq and mass spectrometry were performed. Western blotting and IHC were used for protein expression evaluation. Effects of 3-MA and rapamycin on cells were explored. Immunofluorescence assays were used for immune cell infiltration examination.

RESULTS

ARID1A expression was negatively associated with immune cell infiltration and immune scores for ICIs in LUAD with EGFR mutations. In vitro experiments suggested that ARID1A-KD activates the EGFR/PI3K/Akt/mTOR pathway and inhibits autophagy, which attenuates the inhibition of Rig-I-like receptor pathway activity and type I interferon production in EGFR-mutant LUAD cells. In addition, 3-MA upregulated production of type I interferon in EGFR-mutant LUAD cells, with an similar effect to ARID1A-KD. On the other hand, rapamycin attenuated the enhanced production of type I interferon in ARID1A-KD EGFR-mutant LUAD cells. ARID1A function appears to influence the tumor immune microenvironment and response to ICIs.

CONCLUSION

ARID1A deficiency reverses response to ICIs in EGFR-mutant LUAD by enhancing autophagy-inhibited type I interferon production. Video Abstract.

Comprehensive genomic profiling of Finnish lung adenocarcinoma cohort reveals high clinical actionability and SMARCA4 altered tumors with variable histology and poor prognosis

INTRODUCTION

Lung adenocarcinoma is the most common type of lung cancer and typically carries a high number of mutations. However, the genetic background of the tumors varies according to patients' ethnic background and smoking status. Little data is available on the mutational landscape and the frequency of actionable genomic alterations in lung adenocarcinoma in the Finnish population.

MATERIALS AND METHODS

We evaluated the gene alteration frequencies of 135 stage I-IV lung adenocarcinomas operated at Turku University Hospital between 2004 and 2017 with a large commercial comprehensive genomic profiling panel. Additionally, we correlated the alterations in selected genes with disease outcomes in 115 stage I-III patients with comprehensive follow-up data. The genomic alterations in a sub-cohort of 30 never-smokers were assessed separately.

RESULTS

Seventy percent of patients in the overall cohort and 77% in the never-smoker sub-cohort harbored an alteration or a genomic signature targetable by FDA and/or EMA approved drug for non-small cell carcinoma, respectively. In multivariable analysis for disease-specific survival, any alteration in SMARCA4 (DSS; HR 3.911, 95%CI 1.561-9.795, P=0.004) exhibited independent prognostic significance along with stage, tumor mutation burden, and predominant histological subtypes.

CONCLUSIONS

Over two thirds of our overall cohort, and especially never-smokers had an actionable genomic alteration or signature. SMARCA4 alterations, detected in 7.4% of the tumors, independently predicted a shortened overall and disease-specific survival regardless of the alteration type. Most SMARCA4 alterations in our cohort were missense mutations associated with differentiated predominant histological subtypes and immunohistochemical SMARCA4/BRG1 and TTF-1 positive status.

Clinicopathologic Characteristics and Outcomes for Patients With KRAS G12D-Mutant NSCLC

Introduction

Co-occurring mutations in KRAS-mutant NSCLC are associated with discrete biological properties and modulate therapeutic susceptibilities. As G12D-specific inhibitors are expected to enter the clinic, we sought to investigate the characteristics and outcomes of patients with KRAS G12D-mutant NSCLC.

Methods

This was a retrospective single-institution study. Patients with NSCLC and KRAS G12D mutations detected by the Massachusetts General Hospital SNaPshot next-generation sequencing assay were identified. Clinical and pathologic characteristics were collected by chart review.

Results

A total of 107 patients with KRAS G12D-mutant NSCLC were identified. Most patients were former smokers (80, 74.8%) and had tumors with adenocarcinoma pathologic subtype (93, 86.9%). Among 56 patients evaluated for programmed death-ligand 1 expression, tumor proportion score was less than 50% in 43 (76.8%). Concomitant mutations were identified in STK11 (17 of 107, 15.9%), KEAP1 (10 of 58, 17.2%), TP53 (36 of 107, 33.6%), and SMARCA4 (11 of 107, 10.3%). Among 57 patients treated with first-line therapy, patients with STK11 co-mutations had shorter progression-free survival (1.2 mo, 95% confidence interval [CI]: 0.6–2.9 versus 4.1 mo, 95% CI: 2.5–6.0, p = 0.0235) and overall survival (4.3 mo, 95% CI: 1.2–10.6 versus 17.9 mo, 95% CI: 8.6–31.1, p = 0.0018) compared with wild type. Patients with KEAP1 co-mutations had shorter overall survival (4.6 mo, 95% CI: 1.2–10.6 versus 17.9 mo, 95% CI: 7.1–30.1, p = 0.0125) than those without. TP53 co-mutations exerted no influence on survival.

Conclusions

Co-occurring mutations were common in patients with KRAS G12D-mutant NSCLC. STK11 and KEAP1 co-mutations were associated with worse clinical outcomes, whereas co-occurring TP53 did not affect survival.

[Analysis of Clinicopathologic Features of 9 Cases of SMARCA4-deficient Non-small Cell Lung Cancer]

BACKGROUND

SMARCA4-deficient non-small cell lung cancer (SMARCA4-dNSCLC) is a rare primary lung malignancy. These diseases are not listed separately in the 2021 World Health Organization (WHO) classification of lung neoplasms, but they have special morphological, immunophenotypic and molecular genetic characteristics. This study aims to improve understanding of SMARCA4-dNSCLC by discussing the clinicopathological features, diagonosis and differential diagnosis of the disease.

METHODS

The clinical and imaging data of 9 cases of SMARCA4-dNSCLC diagnosed in Shanghai Changhai Hospital from January 2020 to March 2022 were collected. The clinicopathological features were analyzed by histological and immunohistochemical staining, and the literature was reviewed.

RESULTS

The median age of 9 patients was 65 years old. Six men were smokers. The average maximum diameter of tumor was 3.3 cm. Six cases had been metastasized. The imaging showed that it was an infiltrating mass with unclear boundary and 3 cases invaded the pleura. Nine cases were diagnosed as SMARCA4-dNSCLC, which mainly showed three pathological forms including classic lung adenocarcinoma, mucinous adenocarcinoma and poorly differentiated carcinoma. Poorly differentiated tumor cells are epithelioid, syncytial or rhabdomyoid, the cytoplasm was rich, the cytoplasm could be completely transparent to eosinophilic, eosinophilic globules or small abscesses could be seen, showing solid flakes, with more inflammatory cells and flake necrosis in the stroma. Immunohistochemistry showed that SMARCA4 was negative in all cases and eight cases demonstrated cytokeratin 5.2 (CAM5.2) and cytokeratin 7 (CK7) was diffusely strongly positive, p40 was negative, thyroid transcription factor-1 (TTF-1) was negative in 6 cases, partially positive in 2 cases and diffusely positive in 1 case.

CONCLUSIONS

SMARCA4-dNSCLC is a rare subtype of lung cancer with complex and diverse pathological morphology. The characteristic of immunohistochemical phenotype can assist in the diagnosis.

Thoracic SMARCA2-deficient But SMARCA4-preserved Tumors With Undifferentiated Morphology Combined With Claudin-4 Negativity

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently recognized tumor characterized by inactivation of SMARCA4, a SWItch/Sucrose NonFermentable chromatin remodeler, detectable by immunohistochemistry. SMARCA4-UT shows undifferentiated or rhabdoid morphology with claudin-4 negativity. However, thoracic undifferentiated tumors with the same histologic features as SMARCA4-UTs but a preserved SMARCA4 expression have so far been underrecognized. We herein report 3 cases of thoracic undifferentiated tumors with isolated loss of SMARCA2 but retained expression of SMARCA4 and SMARCB1. The present tumors were found in 2 men and 1 woman, 40 to 50 years old. All patients were heavy smokers (≥20 pack-years). The tumors were generally large masses located in the mediastinum, lung>chest wall, or lung and composed of relatively monotonous, round to epithelioid cells with variably rhabdoid cells. Immunohistochemically, the tumors showed claudin-4 negativity with variable expression of cytokeratin. All cases showed highly aggressive clinical behavior with overall survival of 2 to 10 months. These SMARCA2-deficient tumors with preserved SMARCA4 expression appeared to be clinicopathologically indistinguishable from SMARCA4-UTs, except for in their SMARCA4 status. This variant may expand the spectrum of SWItch/Sucrose NonFermentable-deficient undifferentiated tumors of the thoracic region beyond SMARCA4-UT.

Cytomorphologic and immunophenotypical analysis of SMARCA4 (BRG1)-deficient non-small cell lung carcinoma

INTRODUCTION

Inactivation of SMARCA4/BRG1 (Brahma-related gene 1), a member of the switch/sucrose nonfermentable subfamily of adenosine triphosphate-dependent chromatin remodeling complexes, has been demonstrated in a subset of non-small cell lung carcinomas (NSCLCs). However, the cytomorphologic features of SMARCA4-deficient NSCLCs (SMARCA4-dNSCLC) have only rarely been reported.

MATERIALS AND METHODS

Eight cytology cases of SMARCA4-dNSCLC and eight SMARCA4-retained NSCLC (SMARCA4-rNSCLC) cases were retrieved from our institution's database. These were compared cytologically and immunophenotypically.

RESULTS

All 8 patients with SMARCA4-dNSCLC had a smoking history, and 4 of 8 cases had a prior cancer history. Cytologically, the tumors demonstrated predominantly loosely cohesive and high-grade epithelioid cells with markedly pleomorphic nuclei and prominent nucleoli. Binucleated/multinucleated cells were seen in 5 cases. Six cases showed focal plasmacytoid morphology, and 2 cases showed necrosis. In contrast, in all 8 cases of SMARCA4-rNSCLC, the aspirates were predominantly cohesive with focal, loosely cohesive epithelioid cells showing mild to moderate pleomorphism and lacked necrosis. Only 1 case showed multinucleated cells. All 8 cases of SMARCA4-dNSCLC showed an immunoprofile similar to that of the SMARCA4-rNSCLC cases, including immunoreactivity for AE1/AE3, a lack of immunoreactivity for thyroid transcription factor-1/Napsin A, and p40/p63 but with a loss of BRG1 expression.

CONCLUSIONS

SMARCA4-dNSCLCs exhibited high-grade cytologic features with marked pleomorphism and might show multinucleation and plasmacytoid morphology. In contrast, SMARCA4-rNSCLCs often show mild to moderate pleomorphism with round to polygonal shapes. Both characteristically lack expression of lung adenocarcinoma/squamous markers. Increased awareness of their cytomorphologic features on fine needle aspiration can ensure consideration of the diagnosis.

Multi-omic alterations of the SWI/SNF complex define a clinical subgroup in lung adenocarcinoma

SWI/SNF complexes are major targets of mutations in cancer. Here, we combined multiple “-omics” methods to assess SWI/SNF composition and aberrations in LUAD. Mutations in lung SWI/SNF subunits were highly recurrent in our LUAD cohort (41.4%), and over 70% of the mutations were predicted to have functional impact. Furthermore, SWI/SNF expression in LUAD suffered an overall repression that could not be explained exclusively by genetic alterations. Finally, SWI/SNF mutations were associated with poorer overall survival in TCGA-LUAD. We propose SWI/SNF-mutant LUAD as a separate clinical subgroup with practical implications.

ARID1A Downregulation Predicts High PD-L1 Expression and Worse Clinical Outcome in Patients With Gallbladder Cancer

BACKGROUND

Recent studies have confirmed that AT-rich interactive domain-containing protein 1A (ARID1A) plays a critical role in tumorigenesis, but its role in gallbladder cancer (GBC) remains unclear.

METHODS

In total, 224 patients from Zhongshan Hospital were recruited for this retrospective study. The clinicopathological and baseline characteristics of the patients were collected. Bioinformatics analysis was performed to reveal variations in genes and signaling pathways, and ARID1A and PD-L1 expression and the number of PD1+ tumor-infiltrating lymphocytes (TILs) were measured by immunohistochemical staining.

RESULTS

ARID1A expression was negatively correlated with overall survival in patients with GBC, and multivariate analysis identified ARID1A as an independent prognostic factor for overall survival. A heatmap and gene set enrichment analysis suggested that cytotoxic T lymphocyte signatures and immune-related signaling pathways were downregulated in ARID1A low tumors. Subsequent immunohistochemical staining confirmed that ARID1A expression was negatively correlated with PD-L1 expression and PD1+ TILs in the tumor microenvironment. The Kaplan-Meier analysis suggested that high ARID1A expression combined with low PD-L1 expression or low PD1+ TIL counts is associated with the best prognosis in patients with GBC.

CONCLUSION

ARID1A inactivation can lead to a worse prognosis in patients with GBC, potentially by mediating immune evasion through the PD1/PD-L1 pathway.

Upregulated Expression of Actin-Like 6A is a Risk Factor Affecting the Prognosis of Pancreatic Cancer

Purpose

Actin-like 6A (ACTL6A), a regulatory subunit of the ATP-dependent chromatin-remodeling complex SWI/SNF, acts as an oncogenic factor. This study is aimed at evaluating the correlation between ACTL6A expression and clinicopathological parameters in pancreatic cancer (PC) patients.

Methods

The differences of Actl6a mRNA expression between PC tissues and normal pancreatic tissues were analyzed in public databases, and ACTL6A expression was then determined and confirmed in 60 paired tissue specimens using immunohistochemistry staining. The association analysis between ACTL6A expression and the clinicopathological characteristics was analyzed, as well as Kaplan–Meier survival analysis. Univariate and multivariate Cox analyses were performed to identify the prognostic factors in the overall survival (OS) of patients with PC.

Results

The mRNA expression of Actl6a showed significantly higher in PC compared to normal controls (p < 0.05) from public databases. The score of immunohistochemistry staining further confirmed that ACTL6A expression was significantly upregulated in PC tissues (p < 0.001) through immunohistochemistry staining. High ACTL6A expression was associated with lymphovascular space invasion of PC. Kaplan–Meier analysis revealed that the high expression of ACTL6A was markedly associated with poor OS. Moreover, univariate and multivariate analysis demonstrated that ACTL6A acted as an independent risk factor for PC prognosis.

Conclusion

ACTL6A is upregulated in PC and acts as a risk factor for poor prognosis in patients with PC, and therefore clinicians could around it design preventive measures and individualized treatment to improve mortality in patients with PC.

Unusual lung tumors-from morphology to genetics

Most pathologists are well versed in the diagnosis of lung cancer, given the common nature of the disease. Occasionally more unusual neoplasms are encountered in lung biopsies and resections, which may be difficult to distinguish from "run of the mill" lung cancer cases based on overlapping morphologic and immunophenotypic features. The accurate diagnosis of these rare entities is quite challenging and requires careful morphological examination paired with judicious use of ancillary immunohistochemical and genetic studies. Herein, the clinicopathological and genetic features of five unusual lung tumors will be reviewed, including thoracic SMARCA4-deficient undifferentiated tumor, NUT carcinoma, sclerosing pneumocytoma, primary pulmonary myxoid sarcoma/angiomatoid fibrous histiocytoma, and bronchiolar adenoma/ ciliated muconodular papillary tumor. Since recognition of these entities by pathologists is of increasing importance to guide prognosis and therapy, emphasis will be placed on practical tips to reach these rare diagnoses with confidence.

Implication of ARID1A Undercurrents and PDL1, TP53 Overexpression in Advanced Gastric Cancer

AT-rich interactive domain-containing protein 1A (ARID1A), TP53 and programmed cell death-ligand 1 (PDL1) are involved in several protein interactions that regulate the expression of various cancer-related genes involved in the progression of the cell cycle, cell proliferation, DNA repair, and apoptosis. In addition, gene expression analysis identified some common downstream targets of ARID1A and TP53. It has been established that tumors formed by ARID1A-deficient cancer cells exhibited elevated PDL1 expression. However, the aberrations in these molecules have not been studied in this population especially in Gastric Cancer (GC). In this backdrop we aimed to investigate the role of the ARID1A mutation and expression of ARID1A, TP53 and PDL1 genes in the etiopathogenesis of Gastric Cancer (GC) in the ethnic Kashmiri population (North India). The study included 103 histologically confirmed GC cases. The mutations, if any, in exon-9 of ARID1A gene was analysed by Polymerase Chain Reaction (PCR) followed by Sanger sequencing. The mRNA expression of the ARID1A, TP53 and PDL1 genes was analysed by Quantitative real time-PCR (qRT-PCR). We identified a nonsense mutation (c.3219; C > T) in exon-9 among two GC patients (∼2.0%), which introduces a premature stop codon at protein position 1073. The mRNA expression of the ARID1A, TP53 and PDL1 gene was significantly reduced in 25.3% and elevated in 47.6 and 39.8% of GC cases respectively with a mean fold change of 0.63, 2.93 and 2.43. The data revealed that reduced mRNA expression of ARID1A and elevated mRNA expression of TP53 and PDL1 was significantly associated with the high-grade and advanced stage of cancer. Our study proposes that ARAD1A under-expression and overexpression of TP53 and PDL1 might be crucial for tumor progression with TP53 and PDL1 acting synergistically.

TTF1-positive SMARCA4/BRG1 deficient lung adenocarcinoma

SMARCA4/BRG1-deficient lung adenocarcinoma (SD-LUAD) is being recognized as a distinct subtype based on subtle differences in its clinical, morphological, and immunophenotypic attributes compared to other non–small cell lung carcinomas. We present here a case of SD-LUAD with curious thyroid transcription factor 1 (TTF1) expression in a morphologically heterogenous lung adenocarcinoma. The better differentiated area showed preservation of TTF1 expression, and a poorly differentiated tumor had loss of TTF1 expression with universal BRG1 loss.

ARID1A serves as a receivable biomarker for the resistance to EGFR-TKIs in non-small cell lung cancer

ARID1A is a key component of the SWI/SNF chromatin remodeling complexes which is important for the maintaining of biological processes of cells. Recent studies had uncovered the potential role of ARID1A alterations or expression loss in the therapeutic sensitivity of cancers, but the studies in this field requires to be further summarized and discussed. Therefore, we proposed a series of mechanisms related to the resistance to EGFR-TKIs induced by ARID1A alterations or expression loss and the potential therapeutic strategies to overcome the resistance based on published studies. It suggested that ARID1A alterations or expression loss might be the regulators in PI3K/Akt, JAK/STAT and NF-κB signaling pathways which are strongly associated with the resistance to EGFR-TKIs in NSCLC patients harboring sensitive EGFR mutations. Besides, ARID1A alterations or expression loss could lead to the resistance to EGFR-TKIs via a variety of processes during the tumorigenesis and development of cancers, including epithelial to mesenchymal transition, angiogenesis and the inhibition of apoptosis. Based on the potential mechanisms related to ARID1A, we summarized that the small molecular inhibitors targeting ARID1A or PI3K/Akt pathway, the anti-angiogenic therapy and immune checkpoint inhibitors could be used for the supplementary treatment for EGFR-TKIs among NSCLC patients harboring the concomitant alterations of sensitive EGFR mutations and ARID1A.

A Pan-Cancer Analysis of SMARCA4 Alterations in Human Cancers

Background

SMARCA4, the essential ATPase subunit of SWI/SNF chromatin remodeling complex, regulates transcription through the control of chromatin structure and is increasingly thought to play significant roles in human cancers. This study aims to explore the potential role of SMARCA4 with a view to providing insights on pathologic mechanisms implicated here.

Methods

The potential roles of SMARCA4 in different tumors were explored based on The Cancer Genome Atlas (TCGA), Genotype-tissue expression (GTEx), Tumor Immune Estimation Resource (TIMER), and Gene Set Enrichment Analysis (GSEA) datasets. The expression difference, mutation and phosphorylation status, survival, pathological stage, DNA methylation, tumor mutation burden (TMB), microsatellite instability (MSI), mismatch repair (MMR), tumor microenvironment (TME), and immune cell infiltration related to SMARCA4 were analyzed.

Results

High expression levels of SMARCA4 were observed in most cancer types. SMARCA4 expression in tumor samples correlates with poor overall survival in several cancers. Lung adenocarcinoma cases with altered SMARCA4 showed a poorer prognosis. Enhanced phosphorylation levels of S613, S695, S699, and S1417 were observed in several tumors, including breast cancer. SMARCA4 correlated with tumor immunity and associated with different immune cells and genes in different cancer types. TMB, MSI, MMR, and DNA methylation correlated with SMARCA4 dysregulation in cancers. SMARCA4 expression was negatively associated with CD8+ T-cell infiltration in several tumors. Furthermore, the SWI/SNF superfamily-type complex and ATPase complex may be involved in the functional mechanisms of SMARCA4, albeit these data require further confirmation.

Conclusions

Our study offers a comprehensive understanding of the oncogenic roles of SMARCA4 across different tumors. SMARCA4 may correlate with tumor immunity.

Expanding the Immunophenotype Spectrum of SMARCA4-Deficient Non-Small Cell Lung Carcinomas: A Case Series with Neuroendocrine Markers Expression

Aims. In recent years, SMARCA4-deficient nonsmall cell lung cancer (NSCLC) has been recognized as a distinct new subtype of lung cancer, which is characterized by loss of SMARCA4 (Brahma-related gene-1 [BRG1]) protein expression. Only a limited number of SMARCA4-deficient NSCLC case series have been reported, and their clinicopathological features have not yet been fully elucidated. Our main aim was to analyze the clinical history, histology, immunohistochemistry, and molecular pathology of 5 SMARCA4-deficient NSCLC patients with poorly differentiated or undifferentiated histology and neuroendocrine markers expression. Methods and results. Five patients with complete loss of nuclear BRG1 immunostaining were identified among 53 patients of poorly differentiated/undifferentiated NSCLC. We then performed immunohistochemical staining and gene mutation analysis using a real-time polymerase chain reaction. All patients were male aged between 58 and 82 years (average 67.6 years), with smoking exposure. Histologically, the tumors had a relatively monotonous morphology and showed solid nest-like, sheet-like growth, and geographic necrosis. Thyroid transcription factor 1, cytokeratin 7, and Napsin A were all negative (5 of 5). Moreover, all tumors showed a variable expression of neuroendocrine markers, including synaptophysin, chromogranin A and CD56. Hot spot epidermal growth factor receptor/anaplastic large-cell lymphoma kinase/c-ros oncogene 1 mutations were not detected in any of the 5 tumors. Conclusions. To the best of our knowledge, this is the first study that has reported the poorly differentiated morphology with a frequent expression of neuroendocrine markers. Our results have expanded the immunophenotype spectrum of SMARCA4-deficient NSCLC. However, the clinicopathological significance of this subset of SMARCA4-deficient NSCLC should be further clarified in larger series studies.

Loss of ARID1A expression promotes lung adenocarcinoma metastasis and predicts a poor prognosis

BACKGROUND

ARID1A is an essential subunit of SWI/SNF chromatin remodeling complexes. ARID1A gene mutations and loss of ARID1A expression have been observed in a variety of cancers, and to be correlated with invasion, immune escape and synthetic lethality. As yet, however, the biological effect of ARID1A expression and its role in the prognosis of lung adenocarcinoma (LUAD) patients have remained unclear. In this study we aimed to further elucidate the role of ARID1A expression in LUAD in vitro and in vivo and to assess its effect on the clinical prognosis of LUAD patients.

METHODS

ARID1A expression was detected by IHC in tissue samples from LUAD patients. After regular culturing of LUAD cell lines and constructing stable ARID1A knockdown lines, wound healing and Transwell assays were used to assess the role of ARID1A in cell migration and invasion. The effect of ARID1A knockdown on metastasis was verified in vivo. Western blotting was used to examine the expression of target proteins. Univariate and multivariate analyses were performed to assess survival and to provide variables for nomogram construction. In addition, we used the "rms" package to construct a prognostic nomogram based on a Cox regression model.

RESULTS

We found that ARID1A expression serves as an effective prognostic marker for LUAD patients. Loss of ARID1A expression correlated with a poor prognosis, as verified with a nomogram based on a Cox regression model. In addition, we found that ARID1A knockdown promoted LUAD cell proliferation, migration and invasion in vitro and enhanced LUAD metastasis in vivo by activating the Akt signaling pathway.

CONCLUSIONS

Our data indicate that loss of ARID1A expression promotes LUAD metastasis and predicts a poor prognosis in LUAD patients.

Molecular cytology of the respiratory tract and pleura

There is growing evidence that molecular testing is feasible on all types of cytological preparation, which is fortunate as more diagnostic markers and biomarkers for targeted therapies are discovered for use in pulmonary and pleural malignancies. In this article we will discuss the pre-analytic, analytic, and post-analytic (interpretive) considerations for successful implementation of molecular tests for diagnostic and predictive markers in respiratory and pleural cytology. The vast majority of laboratories are familiar with, and have validated their molecular protocols for, formalin-fixed paraffin-embedded surgical specimens, which are not directly applicable to cytology specimens. Thus, rigorous validation must be performed for each type of fixative and cytology preparation before it is implemented in the clinical setting.