Programmed death-ligand 1 expression at tumor invasive front is associated with epithelial-mesenchymal transition and poor prognosis in esophageal squamous cell carcinoma

The roles of PD-L1 in the various stages of tumor metastasis

The interaction between tumor programmed death ligand 1 (PD-L1) and T-cell programmed cell death 1 (PD-1) has long been acknowledged as a mechanism for evading immune surveillance. Recent studies, however, have unveiled a more nuanced role of tumor-intrinsic PD-L1 in reprograming tumoral phenotypes. Preclinical models emphasize the synchronized effects of both intracellular and extracellular PD-L1 in promoting metastasis, with intricate interactions with the immune system. This review aims to summarize recent findings to elucidate the spatiotemporal heterogeneity of PD-L1 expression and the pro-metastatic roles of PD-L1 in the entire process of tumor metastasis. For example, PD-L1 regulates the epithelial-to-mesenchymal transition (EMT) process, facilitates the survival of circulating tumor cells, and induces the formation of immunosuppressive environments at pre-metastatic niches and metastatic sites. And the complexed and dynamic regulation process of PD-L1 for tumor metastasis is related to the spatiotemporal heterogeneity of PD-L1 expression and functions from tumor primary sites to various metastatic sites. This review extends the current understandings for the roles of PD-L1 in mediating tumor metastasis and provides new insights into therapeutic decisions in clinical practice.

Immune checkpoints between epithelial-mesenchymal transition and autophagy: A conflicting triangle

Inhibitory immune checkpoint (ICP) molecules are pivotal in inhibiting innate and acquired antitumor immune responses, a mechanism frequently exploited by cancer cells to evade host immunity. These evasion strategies contribute to the complexity of cancer progression and therapeutic resistance. For this reason, ICP molecules have become targets for antitumor drugs, particularly monoclonal antibodies, collectively referred to as immune checkpoint inhibitors (ICI), that counteract such cancer-associated immune suppression and restore antitumor immune responses. Over the last decade, however, it has become clear that tumor cell-associated ICPs can also induce tumor cell-intrinsic effects, in particular epithelial-mesenchymal transition (EMT) and macroautophagy (hereafter autophagy). Both of these processes have profound implications for cancer metastasis and drug responsiveness. This article reviews the positive or negative cross-talk that tumor cell-associated ICPs undergo with autophagy and EMT. We discuss that tumor cell-associated ICPs are upregulated in response to the same stimuli that induce EMT. Moreover, ICPs themselves, when overexpressed, become an EMT-inducing stimulus. As regards the cross-talk with autophagy, ICPs have been shown to either stimulate or inhibit autophagy, while autophagy itself can either up- or downregulate the expression of ICPs. This dynamic equilibrium also extends to the autophagy-apoptosis axis, further emphasizing the complexities of cellular responses. Eventually, we delve into the intricate balance between autophagy and apoptosis, elucidating its role in the broader interplay of cellular dynamics influenced by ICPs. In the final part of this article, we speculate about the driving forces underlying the contradictory outcomes of the reciprocal, inhibitory, or stimulatory effects between ICPs, EMT, and autophagy. A conclusive identification of these driving forces may allow to achieve improved antitumor effects when using combinations of ICIs and compounds acting on EMT and/or autophagy. Prospectively, this may translate into increased and/or broadened therapeutic efficacy compared to what is currently achieved with ICI-based clinical protocols.

Epithelial-to-mesenchymal transition in cancer progression: unraveling the immunosuppressive module driving therapy resistance

Cancer cells undergo phenotypic switching (cancer cell plasticity) in response to microenvironmental cues, including exposure to therapy/treatment. Phenotypic plasticity enables the cancer cells to acquire more mesenchymal traits promoting cancer cells' growth, survival, therapy resistance, and disease recurrence. A significant program in cancer cell plasticity is epithelial-to-mesenchymal transition (EMT), wherein a comprehensive reprogramming of gene expression occurs to facilitate the translational shift from epithelial-to-mesenchymal phenotypes resulting in increased invasiveness and metastasis. In addition, EMT plays a pivotal role in facilitating cancer cells' escape from the body's immune system using several mechanisms, such as the downregulation of major histocompatibility complex-mediated antigen presentation, upregulation of immune checkpoint molecules, and recruitment of immune-suppressive cells. Cancer cells' ability to undergo phenotypic switching and EMT-driven immune escape presents a formidable obstacle in cancer management, highlighting the need to unravel the intricate mechanisms underlying these processes and develop novel therapeutic strategies. This article discusses the role of EMT in promoting immune evasion and therapy resistance. We also discuss the ongoing research on developing therapeutic approaches targeting intrinsic and induced cell plasticity within the immune suppressive microenvironment. We believe this review article will update the current research status and equip researchers, clinicians, and other healthcare professionals with valuable insights enhancing their existing knowledge and shedding light on promising directions for future cancer research. This will facilitate the development of innovative strategies for managing therapy-resistant cancers and improving patient outcomes.

Dual anti-PD-(L)1/TGF-β inhibitors in cancer immunotherapy - Updated

Immune checkpoint inhibitor (ICI) therapy suffers from tumor resistance and relapse in majority of patients due to the suppressive tumor immune microenvironment (TIME). Advances in the field have brought about development of fusion proteins able to target two signaling simultaneously and to exert maximal anti-cancer immunity. Bispecific inhibitors of transforming growth factor (TGF)-β signaling and programmed death-1 (PD-1) or programmed death-ligand 1 (PD-L1) are developed to reduce the rate of relapse and to achieve durable anti-cancer therapy. TGF-β is well-known for its immunosuppressive activity, and it takes critical roles in promotion of all tumor hallmarks. Bispecific anti-PD-(L)1/TGF-β inhibitors reinvigorate effector activity of CD8+ T and natural killer (NK) cells, hamper regulatory T cell (Treg) expansion, and increase the density of anti-tumor type 1 macrophages (M1). Responses to the bispecific approach are higher compared with solo anti-PD-(L)1 or TGF-β targeted therapy, and are seemingly more pronounced in human papillomavirus (HPV)+ patients. High expression of PD-L1 or immune-excluded phenotype in a tumor can also be markers of better response to the bispecific strategy. Besides, anti-PD-(L)1/TGF-β inhibitor therapy can be used safely with other therapeutic modalities including vaccination, radiation and chemotherapy.

What role does PDL1 play in EMT changes in tumors and fibrosis?

Epithelial-mesenchymal transformation (EMT) plays a pivotal role in embryonic development, tissue fibrosis, repair, and tumor invasiveness. Emerging studies have highlighted the close association between EMT and immune checkpoint molecules, particularly programmed cell death ligand 1 (PDL1). PDL1 exerts its influence on EMT through bidirectional regulation. EMT-associated factors, such as YB1, enhance PDL1 expression by directly binding to its promoter. Conversely, PDL1 signaling triggers downstream pathways like PI3K/AKT and MAPK, promoting EMT and facilitating cancer cell migration and invasion. Targeting PDL1 holds promise as a therapeutic strategy for EMT-related diseases, including cancer and fibrosis. Indeed, PDL1 inhibitors, such as pembrolizumab and nivolumab, have shown promising results in clinical trials for various cancers. Recent research has also indicated their potential benefit in fibrosis treatment in reducing fibroblast activation and extracellular matrix deposition, thereby addressing fibrosis. In this review, we examine the multifaceted role of PDL1 in immunomodulation, growth, and fibrosis promotion. We discuss the challenges, mechanisms, and clinical observations related to PDL1, including the limitations of the PD1/PDL1 axis in treatment and PD1-independent intrinsic PDL1 signaling. Our study highlights the dynamic changes in PDL1 expression during the EMT process across various tumor types. Through interplay between PDL1 and EMT, we uncover co-directional alterations, regulatory pathways, and diverse changes resulting from PDL1 intervention in oncology. Additionally, our findings emphasize the dual role of PDL1 in promoting fibrosis and modulating immune responses across multiple diseases, with potential implications for therapeutic approaches. We particularly investigate the therapeutic potential of targeting PDL1 in type II EMT fibrosis: strike balance between fibrosis modulation and immune response regulation. This analysis provides valuable insights into the multifaceted functions of PDL1 and contributes to our understanding of its complex mechanisms and therapeutic implications.

Comparative analysis of immune checkpoint inhibitors in first-line treatment of esophageal squamous cell carcinoma: a network meta-analysis

Aim: To evaluate the efficacy and safety of first-line immunochemotherapy in the treatment of advanced esophageal squamous cell carcinoma (CRD42021287033). Methods: PubMed, Embase, Cochrane Library and Web of Science were systematically searched to obtain randomized controlled trials, and the outcome indicators of the reports were compared and analyzed. Results: A total of 3163 patients from five reported randomized controlled trials were included in the meta-analysis. The results showed the comprehensive benefits of toripalimab combined with chemotherapy, in terms of overall survival (hazard ratio: 0.59; 95% CI: 0.43-0.81) and progression-free survival (hazard ratio: 0.58; 95% CI: 0.46-0.73). Conclusion: Toripalimab combined with chemotherapy may be a better choice for first-line immunochemotherapy, although this needs to be verified by clinical studies.

Prognostic impact of desmoplastic reaction in esophageal squamous cell carcinoma patients with neoadjuvant therapy

AIM

This study aimed to examine the prognostic value of desmoplastic reaction (DR) in esophageal squamous cell carcinoma (ESCC), particularly in patients who received neoadjuvant therapy, such as chemotherapy (NAC) or chemoradiotherapy (NACRT).

METHOD

In total, 153 patients with pStage II/III ESCC were included in this study. Ninety-one patients received neoadjuvant therapy (NAC, 70; NACRT, 21). Patients were classified according to three DR categories based on the presence of keloid-like collagen and/or myxoid stroma.

RESULTS

In total, 50, 50, and 53 patients were classified as having mature, intermediate, and immature DR, respectively. The weighted kappa coefficient was 0.623 in the patients with preoperative treatments and 0.782, in those without. The 5-year disease-specific survival (DSS) rates in patients with intermediate/immature DR was significantly worse than those with mature DR (40.7% vs. 73.3%, p < 0.001). Similarly, the 5-year DSS rate in patients with intermediate/immature DR was significantly worse than those with mature DR in a study of patients who received neoadjuvant therapy (46.7% vs. 71.2%, p = 0.009). Multivariate analysis revealed that DR (hazard ratio [HR]: 3.15, 95% confidence interval [CI] 1.58-6.27, p = 0.001), along with N factors, was an independent risk factor for DSS. Moreover, multivariate analysis of patients who received neoadjuvant therapy revealed only DR (HR: 2.47, 95% CI 1.02-5.96, p = 0.045) as independent risk factors for DSS.

CONCLUSION

The DR classification was a valuable prognostic factor not only in the ESCC patients without neoadjuvant therapy but also in those with neoadjuvant therapy.

Effect of BIM expression on the prognostic value of PD-L1 in advanced non-small cell lung cancer patients treated with EGFR-TKIs

The role of Programmed Cell Death Ligand 1 (PD-L1) expression in predicting epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs) efficacy remains controversial. Recent studies have highlighted that tumor-intrinsic PD-L1 signaling can be modulated by STAT3, AKT, MET oncogenic pathway, epithelial-mesenchymal transition, or BIM expression. This study aimed to investigate whether these underlying mechanisms affect the prognostic role of PD-L1. We retrospectively enrolled patients with EGFR mutant advanced stage NSCLC who received first-line EGFR-TKI between January 2017 and June 2019, the treatment efficacy of EGFR-TKI was assessed. Kaplan-Meier analysis of progression-free survival (PFS) revealed that patients with high BIM expression had shorter PFS, regardless of PD-L1 expression. This result was also supported by the COX proportional hazard regression analysis. In vitro, we further proved that the knockdown of BIM, instead of PDL1, induced more cell apoptosis following gefitinib treatment. Our data suggest that among the pathways affecting tumor-intrinsic PD-L1 signaling, BIM is potentially the underlying mechanism that affects the role of PD-L1 expression in predicting response to EGFR TKI and mediates cell apoptosis under treatment with gefitinib in EGFR-mutant NSCLC. Further prospective studies are required to validate these results.

Immunological and biological dissection of normal and tumoral salivary glands

Salivary glands naturally play central roles in oral immunity. The salivary glands microenvironment inevitable may be exposed to exogenous factors consequently triggering the initiation and formation of various malignant and benign tumors. Mesenchymal stem cells are recruited into salivary gland microenvironment, interact with tumor cells, and induce inhibitory cytokines as well as cells with immunosuppressive phenotypes such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). The immune components and tumor immune responses in malignant and benign SGTs are still under investigation. Immune responses may directly play a limiting role in tumor growth and expansion, or may participate in formation of a rich milieu for tumor growth in cooperation with other cellular and regulatory molecules. Immune checkpoint molecules (e.g. PDLs, HLA-G and LAG3) are frequently expressed on tumor cells and/or tumor-infiltrating lymphocytes (TILs) in salivary gland microenvironment, and an increase in their expression is associated with T cell exhaustion, immune tolerance and tumor immune escape. Chemokines and chemokine receptors have influential roles on aggressive behaviors of SGTs, and thereby they could be candidate targets for cancer immunotherapy. To present a broad knowledge on salivary glands, this review first provides a brief description on immunological functions of normal salivary glands, and then describe the SGT's tumor microenvironment, by focusing on mesenchymal stem cells, immune cell subsets, immune checkpoint molecules, chemokines and chemokine receptors, and finally introduces immune checkpoint inhibitors as well as potential targets for cancer therapy.

A ruptured sarcomatoid hepatocellular carcinoma treated with combined immunotherapy

Sarcomatoid hepatocellular carcinoma (sHCC) is a rare phenotype of HCC with extremely poor prognosis and no established pharmacological treatment. Interventional therapies such as radiofrequency ablation (RFA) or transcatheter arterial embolization (TAE) have been shown to limit the development of sHCC through mechanisms involving hypoxia-induced epithelial-mesenchymal transition. This report describes an 83-year-old man who developed sHCC 2 years after RFA treatment for HCC and experienced sHCC rupture. Following TAE-induced hematostasis, he was administered lenvatinib for tumor control. Although his physical status had improved, due to loss of fever and attenuation of arterial enhancement in the tumor, for 1 month after lenvatinib administration, tumor re-growth was observed 2 months after lenvatinib treatment. His general condition was preserved, and he was treated with 10 courses of atezolizumab plus bevacizumab (Atez+Bev), resulting in tumor shrinkage that was maintained for 3-8 months after Atez+Bev. Findings in this patient showed that combined immunotherapy was effective for sHCC. Further investigation in additional patients is required to maximize prognosis in patients with sHCC.

Neoadjuvant immunotherapy for resectable esophageal cancer: A review

Esophageal cancer (EC) is one of the most common cancers worldwide, especially in China. Despite therapeutic advances, the 5-year survival rate of EC is still dismal. For patients with resectable disease, neoadjuvant chemoradiotherapy (nCRT) in combination with esophagectomy is the mainstay of treatment. However, the pathological complete response (pCR) rate to nCRT of 29.2% to 43.2% is not satisfactory, and approximately half of the patients will develop either a locoregional recurrence or distant metastasis. It is, therefore, necessary to explore novel and effective treatment strategies to improve the clinical efficacy of treatment. Immunotherapy utilizing immune checkpoint inhibitors (ICIs) has significantly changed the treatment paradigm for a wide variety of advanced cancers, including EC. More recently, increasing clinical evidence has demonstrated that neoadjuvant immunotherapy can potentially improve the survival of patients with resectable cancers. Furthermore, accumulating findings support the idea that chemotherapy and/or radiotherapy can activate the immune system through a variety of mechanisms, so a combination of chemotherapy and/or radiotherapy with immunotherapy can have a synergistic antitumor effect. Therefore, it is reasonable to evaluate the role of neoadjuvant immunotherapy for patients with surgically resectable EC. In this review, we discuss the rationale for neoadjuvant immunotherapy in patients with EC, summarize the current results of utilizing this strategy, review the planned and ongoing studies, and highlight the challenges and future research needs.

Programmed death-ligand 1 signaling and expression are reversible by lycopene via PI3K/AKT and Raf/MEK/ERK pathways in tongue squamous cell carcinoma

Background

Cancer therapy targeting programmed death receptor-1 (PD-1 or CD279) or programmed death-ligand 1 (PD-L1 or CD274) gives hope to Tongue Squamous Cell Carcinoma (TSCC) treatment. However, the tumor-intrinsic mechanism of PD-L1 is not fully elucidated in TSCC. On the other hand, lycopene showed antitumor effects and chemotherapy/radiotherapy-enhancing effects by mechanisms closely correlated with PD-L1.

Purpose

We aimed to explore whether the mechanisms of PD-L1 signaling and regulation are reversible by lycopene treatment in TSCC.

Methods

We collected TSCC tissues and normal tissues for assessment of PD-L1 expression by immunohistochemical technique and western blotting. We measured the expression of PD-L1 in three TSCC cell lines and constructed cell lines with knockdown and overexpression of PD-L1. Then, we measured the proliferation by CCK-8 assay, migration and invasion by Transwell assay, and apoptosis by TUNEL assay in five groups with treatment of blank control, negative control with vector transfection, PD-L1 knockdown/overexpression, 4 μM lycopene, and combined 4 μM lycopene and PD-L1 knockdown/overexpression. We also systematically analyzed the PD-L1 constitutive signaling pathways and their effect EMT pathways. In order to bring out the mechanism underlying PI3K/AKT depressing Raf/MEK/ERK, we used PI3K inhibitor LY294002.

Results

We detected significant PD-L1 upregulation in biopsies by western blot and immunohistochemistry. Our study demonstrated that PD-L1 upregulation elevated IGF-1R to activate the PI3K/AKT pathway but inactivated the Raf/MEK/ERK pathway in TSCC cell line CAL27, while PD-L1 knockdown decreased IGF-1R to inactivate both PI3K/AKT and Raf/MEK/ERK pathways in cell line SCC9, to increase/decrease p-FOXOs and decrease/increase p-GSK-3β, producing further changes in EMT, proliferation, migration, invasion, and apoptosis. Lycopene reversed PD-L1 signaling and expression by mechanisms opposite to PD-L1 upregulation but similar to PD-L1 knockdown.

Conclusion

Taken together, this study firstly confirmed PD-L1 expression and signaling are reversible by lycopene via PI3K/AKT and Raf/MEK/ERK pathways in TSCC. Our study provides a sounder basis for comprehending PD-L1 signaling and expression and prevention and treatment of TSCC.

Bidirectional crosstalk between epithelial-mesenchymal plasticity and IFNγ-induced PD-L1 expression promotes tumour progression

Epithelial-mesenchymal transition (EMT) and immunoevasion through upregulation of programmed death-ligand 1 (PD-L1) are important drivers of cancer progression. While EMT has been proposed to facilitate PD-L1-mediated immunosuppression, molecular mechanisms of their interaction remain obscure. Here, we provide insight into these mechanisms by proposing a mathematical model that describes the crosstalk between EMT and interferon gamma (IFNγ)-induced PD-L1 expression. Our model shows that via interaction with microRNA-200 (miR-200), the multi-stability of the EMT regulatory circuit is mirrored in PD-L1 levels, which are further amplified by IFNγ stimulation. This IFNγ-mediated effect is most prominent for cells in a fully mesenchymal state and less strong for those in an epithelial or partially mesenchymal state. In addition, bidirectional crosstalk between miR-200 and PD-L1 implies that IFNγ stimulation allows cells to undergo EMT for lower amounts of inducing signal, and the presence of IFNγ accelerates EMT and decelerates mesenchymal-epithelial transition (MET). Overall, our model agrees with published findings and provides insight into possible mechanisms behind EMT-mediated immune evasion, and primary, adaptive, or acquired resistance to immunotherapy. Our model can be used as a starting point to explore additional crosstalk mechanisms, as an improved understanding of these mechanisms is indispensable for developing better diagnostic and therapeutic options for cancer patients.

PD-L1 Expression in Colorectal Adenocarcinoma Is Associated With the Tumor Immune Microenvironment and Epithelial-Mesenchymal Transition

OBJECTIVES

Colorectal carcinomas are the third-most common tumors in the world, and colorectal cancer ranks second in cancer-related deaths. Our aim in this study was to investigate the correlation between programmed cell death ligand 1 (PD-L1) expression and clinicopathologic parameters in colorectal carcinomas and their relationship to the tumor immune microenvironment, epithelial-mesenchymal transition (EMT), and microsatellite instability. We also investigated the predictive and prognostic role of PD-L1.

METHODS

One hundred patients with a diagnosis of colorectal adenocarcinoma who did not receive neoadjuvant therapy were included in the study. The relationships among the altered expression of PD-L1; vimentin; E-cadherin; mismatch repair status; and pathologic microenvironmental features, including the presence of tumor budding and CD8-positive tumor infiltrating lymphocytes (TILs), were assessed.

RESULTS

Increased PD-L1 expression in tumor cells was associated with increased TILs (P = .013), high histologic grade (P = .011), advanced pathologic T stage (P = .007), lymph node metastasis (P = .002), distant metastasis (P < .001), perineural invasion (P = .009), high bud score (P = .023), EMT (P < .001), and shorter disease-free survival (P = .029).

CONCLUSIONS

Overall, PD-L1 expression in colorectal carcinoma tumor cells is a marker of poor prognosis, and the positive correlation detected between EMT status and PD-L1 expression suggests that patients with the mesenchymal phenotype may be more likely to benefit from programmed cell death 1 protein/PD-L1 immunotherapy.

Current and Future Immunotherapy-Based Treatments for Oesophageal Cancers

Oesophageal cancer is a disease that causes significant morbidity and mortality worldwide, and the prognosis of this condition has hardly improved in the past few years. Standard treatment includes a combination of chemotherapy, radiotherapy and surgery; however, only a proportion of patients go on to treatment intended to cure the disease due to the late presentation of this disease. New treatment options are of utmost importance, and immunotherapy is a new option that has the potential to transform the landscape of this disease. This treatment is developed to act on the changes within the immune system caused by cancer, including checkpoint inhibitors, which have recently shown great promise in the treatment of this disease and have recently been included in the adjuvant treatment of oesophageal cancer in many countries worldwide. This review will outline the mechanisms by which cancer evades the immune system in those diagnosed with oesophageal cancer and will summarize current and ongoing trials that focus on the use of our own immune system to combat disease.

Programmed Death-Ligand 1 (PD-L1) Positivity and Factors Associated with Poor Prognosis in Patients with Gastric Cancer: An Umbrella Meta-Analysis

Gastric cancer (GC) is one of the most common malignancies throughout the world with late diagnosis and poor prognosis. The expression of programmed death-ligand 1 (PD-L1) in GC is attributed to immune evasion and tumor progression. PD-L1 positivity has both predictive and prognostic biomarker potential. Aiming to summarize a large amount of research and to provide a definitive conclusion to the conflicting results on the prognostic significance of PD-L1 expression in GC, we performed an umbrella review based on existing meta-analyses which were published recently (2016-2021) and indexed in the PubMed database. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used in August 2021 to screen articles, and data extraction with quality assessment was performed on the selected meta-analyses. Review Manager (RevMan) 5.3 software was used to analyze the HR and OR with a 95% confidence interval (CI) among PD-L1 positive GC patients. We also assessed the between-study heterogeneity (I ²). Forest and Funnel plots were obtained, and a P-value of <0.05 was considered statistically significant. A total of 567 articles were screened, and we selected three meta-analyses with a total of 40 studies conducted over a period of 14 years. In our umbrella review, a total of 8,419 GC patients with an average PD-L1 positivity of 39% were analyzed. We found that PD-L1 positivity in GC patients is associated with poor prognosis (pooled HR =1.44, 95% CI: 1.24-1.68, P<0.00001) having higher mortality reducing the chances of overall survival (OS). However, there are no significant differences in PD-L1 expression among different lymph node (LN) metastases (OR=1.31, 95% CI: 0.98-1.74, P=0.07) and tumor, node, and metastasis (TNM) stages (OR=1.13, 95% CI: 0.80-1.58, P=0.50). Early identification of PD-L1 expression may help tailor cost-effective and targeted immunotherapy among GC patients. More research is needed to further understand how PD-L1 affects LN metastasis and tumor invasion.

Inhibition of DCLK1 kinase reverses epithelial-mesenchymal transition and restores T-cell activity in pancreatic ductal adenocarcinoma

Immunotherapy has recently become a promising cancer therapy with extensive applications of immune checkpoint inhibitors (ICIs). However, pancreatic ductal adenocarcinoma (PDAC) appears to be unresponsive to immunotherapy due to the immunosuppressive microenvironment. Recent studies showed that cancer stem cell marker DCLK1 promoted the initiation and development of PDAC. Nevertheless, the mechanism driving this process remains unclear. Here, by performing gain-of-function investigations in PDAC cell lines, we demonstrate that both DCLK1 long (DCLK1-iso1, DCLK1-AS) and short (DCLK1-iso4, DCLK1-BL) isoforms can efficiently activate EMT leading to tumor migration and invasion. Consistent with experiments in vitro, bioinformatic analysis demonstrates that DCLK1 may act as a driver of EMT activation in PDAC. Further analysis showed that EMT was associated with an immunosuppressive microenvironment, which includes more immunosuppressive cells and chemokines, and patients with a higher EMT score were less sensitive to immune checkpoint inhibitors according to the TIDE (Tumor Immune Dysfunction and Exclusion) algorithm. Multiplexed immunofluorescence results demonstrated the close correlation between DCLK1, EMT and immunosuppression in PDAC patients. The findings were further confirmed in vivo reflected by decreased CD4+, CD8+ T cells and increased M2 macrophages as well as E-cad loss in DCLK1-overexpressing subcutaneous tumors. Importantly, the highly-specific DCLK1 inhibitor (DCLK1-IN-1) was able to effectively block EMT process and restore T-cell activity. Altogether, our data demonstrate that DCLK1 is strongly associated with tumor immune escape in PDAC and inhibiting DCLK1 kinase activity may be a promising therapeutic modality.

METTL3/IGF2BP3 axis inhibits tumor immune surveillance by upregulating N6-methyladenosine modification of PD-L1 mRNA in breast cancer

BACKGROUND

Continual expression of PD-L1 in tumor cells is critical for tumor immune escape and host T cell exhaustion, however, knowledge on its clinical benefits through inhibition is limited in breast cancer. N⁶-methyladenosine (m⁶A) plays a crucial role in multiple biological activities. Our study aimed to investigate the regulatory role of the m⁶A modification in PD-L1 expression and immune surveillance in breast cancer.

METHODS

MeRIP-seq and epitranscriptomic microarray identified that PD-L1 is the downstream target of METTL3. MeRIP-qPCR, absolute quantification of m⁶A modification assay, and RIP-qPCR were used to examine the molecular mechanism underlying METTL3/m⁶A/IGF2BP3 signaling axis in PD-L1 expression. B-NDG and BALB/c mice were used to construct xenograft tumor models to verify the phenotypes upon METTL3 and IGF2BP3 silencing. In addition, breast cancer tissue microarray was used to analyze the correlation between PD-L1 and METTL3 or IGF2BP3 expression.

RESULTS

We identified that PD-L1 was a downstream target of METTL3-mediated m⁶A modification in breast cancer cells. METTL3 knockdown significantly abolished m⁶A modification and reduced stabilization of PD-L1 mRNA. Additionally, METTL3-mediated PD-L1 mRNA activation was m⁶A-IGF2BP3-dependent. Moreover, inhibition of METTL3 or IGF2BP3 enhanced anti-tumor immunity through PD-L1-mediated T cell activation, exhaustion, and infiltration both in vitro and in vivo. PD-L1 expression was also positively correlated with METTL3 and IGF2BP3 expression in breast cancer tissues.

CONCLUSION

Our study suggested that METTL3 could post-transcriptionally upregulate PD-L1 expression in an m⁶A-IGF2BP3-dependent manner to further promote stabilization of PD-L1 mRNA, which may have important implications for new and efficient therapeutic strategies in the tumor immunotherapy.

Prognostic Value of Programmed Death Ligand-1 Expression in Solid Tumors Irrespective of Immunotherapy Exposure: A Systematic Review and Meta-Analysis

BACKGROUND

The programmed cell death-1/programmed cell death ligand-1 (PD-L1) pathway, which plays a crucial role in cancer immune surveillance, is the target of several approved immunotherapeutic agents and is used as a predictive biomarker in some solid tumors. However, its use as a prognostic marker (i.e., regardless of therapy used) is not established clearly with available data demonstrating inconsistent prognostic impact of PD-L1 expression in solid tumors.

METHODS

We conducted a systematic literature search of electronic databases and identified publications exploring the effect of PD-L1 expression on overall survival and/or disease-free survival. Hazard ratios were pooled in a meta-analysis using generic inverse-variance and random-effects modeling. We used the Deeks method to explore subgroup differences based on disease site, stage of disease, and method of PD-L1 quantification.

RESULTS

One hundred and eighty-six studies met the inclusion criteria. Programmed cell death ligand-1 expression was associated with worse overall survival (hazard ratio 1.33, 95% confidence interval 1.26-1.39; p < 0.001). There was significant heterogeneity between disease sites (subgroup p = 0.002) with pancreatic, hepatocellular, and genitourinary cancers associated with the highest magnitude of adverse outcomes. Programmed cell death ligand-1 was also associated with worse overall disease-free survival (hazard ratio 1.19, 95% confidence interval 1.09-1.30; p < 0.001). Stage of disease did not significantly affect the results (subgroup p = 0.52), nor did the method of quantification via immunohistochemistry or messenger RNA (subgroup p = 0.70).

CONCLUSIONS

High expression of PD-L1 is associated with worse survival in solid tumors albeit with significant heterogeneity among tumor types. The effect is consistent in early-stage and metastatic disease and is not sensitive to method of PD-L1 quantification. These data can provide additional information for the counseling of patients with cancer about prognosis.

Immunosuppressive Traits of the Hybrid Epithelial/Mesenchymal Phenotype

Recent preclinical and clinical data suggests enhanced metastatic fitness of hybrid epithelial/mesenchymal (E/M) phenotypes, but mechanistic details regarding their survival strategies during metastasis remain unclear. Here, we investigate immune-evasive strategies of hybrid E/M states. We construct and simulate the dynamics of a minimalistic regulatory network encompassing the known associations among regulators of EMT (epithelial-mesenchymal transition) and PD-L1, an established immune-suppressor. Our simulations for the network consisting of SLUG, ZEB1, miR-200, CDH1 and PD-L1, integrated with single-cell and bulk RNA-seq data analysis, elucidate that hybrid E/M cells can have high levels of PD-L1, similar to those seen in cells with a full EMT phenotype, thus obviating the need for cancer cells to undergo a full EMT to be immune-evasive. Specifically, in breast cancer, we show the co-existence of hybrid E/M phenotypes, enhanced resistance to anti-estrogen therapy and increased PD-L1 levels. Our results underscore how the emergent dynamics of interconnected regulatory networks can coordinate different axes of cellular fitness during metastasis.

Clinicopathological and Prognostic Value of Programmed Cell Death 1 Expression in Hepatitis B Virus-related Hepatocellular Carcinoma: A Meta-analysis

BACKGROUND AND AIMS

The efficacy of targeted programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) monoclonal antibodies (mAbs) has been confirmed in many solid malignant tumors. The overexpression of PD-1/PD-L1 serves as a biomarker to predict prognosis and clinical progression. However, the role of PD-1 in patients with hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) remains indeterminate. Given that HBV is the most important cause for HCC, this study aimed to investigate the prognostic and clinicopathological value of PD-1 in HBV-HCC via a meta-analysis.

METHODS

We searched PubMed, Embase, Scopus, the Cochrane Library, Web of Science and Google Scholar up to January 2021 for studies on the correlation between clinicopathology/prognosis and PD-1 in patients with HBV-HCC. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to investigate the prognostic significance of PD-1 expression. The odds ratios (ORs) and 95% CIs were determined to explore the association between PD-1 expression and clinicopathological features.

RESULTS

Our analysis included seven studies with 658 patients, which showed that high PD-1 expression was statistically correlated with poorer overall survival (HR=2.188, 95% CI: [1.262-3.115], p<0.001) and disease-free survival (HR=2.743, 95% CI: [1.980-3.506], p<0.001). PD-1 overexpression was correlated with multiple tumors (OR=2.268, 95% CI: [1.209-4.257], p=0.011), high level of alpha fetoprotein (AFP; OR=1.495, 95% CI: [1.005-2.223], p=0.047) and advanced Barcelona Clinic Liver Cancer (BCLC) stage (OR=3.738, 95% CI: [2.101-6.651], p<0.001).

CONCLUSIONS

Our meta-analysis revealed that the high level of PD-1 expression was associated with multiple tumors, high level of AFP and advanced BCLC stage. It significantly predicted a poor prognosis of HBV-HCC, which suggests that anti-PD-1 therapy for HBV-HCC patients is plausible.

NHS-IL12 and bintrafusp alfa combination therapy enhances antitumor activity in preclinical cancer models

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Combination therapy induced both adaptive and innate antitumor immunity.

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Combination therapy significantly enhanced antitumor activity.

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Combination therapy generated tumor antigen specific immune memory.

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Bintrafusp alfa mediated the reduction of lung metastases.

Combinatorial immunotherapy approaches are emerging as viable cancer therapeutic strategies for improving patient responses and outcomes. This study investigated whether two such immunotherapies, with complementary mechanisms of action, could enhance antitumor activity in murine tumor models. The immunocytokine NHS-IL12, and surrogate NHS-muIL12, are designed to deliver IL-12 and muIL-12, respectively, to the tumor microenvironment (TME) to activate NK cells and CD8⁺ T cells and increase their cytotoxic functions. Bintrafusp alfa (BA) is a bifunctional fusion protein composed of the extracellular domains of the TGF-β receptor II to function as a TGF-β “trap” fused to a human IgG1 antibody blocking PD-L1. With this dual-targeting strategy, BA enhances efficacy over that of monotherapies in preclinical studies. In this study, NHS-muIL12 and BA combination therapy enhanced antitumor activity, prolonged survival, and induced tumor-specific antitumor immunity. This combination therapy increased tumor-specific CD8⁺ T cells and induced immune profiles, consistent with the activation of both adaptive and innate immune systems. In addition, BA reduced lung metastasis in the 4T1 model. Collectively, these findings could support clinical trials designed to investigate NHS-IL12 and BA combination therapy for patients with advanced solid tumors

Cross-Talk Between Tumor Cells Undergoing Epithelial to Mesenchymal Transition and Natural Killer Cells in Tumor Microenvironment in Colorectal Cancer

Tumor cells undergoing epithelial to mesenchymal transition (EMT) and immune cells in tumor microenvironment (TME) reciprocally influence each other. Immune cells, by supplying TME with bioactive molecules including cytokines, chemokines, enzymes, metabolites, and by physical interactions with tumor cells via their receptors, represent an important factor that affects EMT. Chronical inflammation in TME favorizes tumor growth and invasiveness and stimulates synthesis of EMT promoting transcription factors. Natural killer (NK) cells, owing to their unique ability to exert cytotoxic function independent of major histocompatibility (MHC)-mediated antigen presentation, play a significant role in the control of metastasis in colorectal cancer (CRC). Although, the cross-talk between immune cells and tumor cells in general favors the induction of EMT and inhibition of antitumor immune responses, there are some changes in the immunogenicity of tumor cells during EMT of CRC cells that increase their susceptibility to NK cell cytotoxic lysis. However, suppressive TME downmodulates the expression of activating NK cell receptors, decreases the expression of activating and increases the expression of inhibitory NK cell ligands on tumor cells, and impairs NK cell metabolism that altogether negatively affects the overall NK cell function. Furthermore, process of EMT is often associated with increased expression of programmed cell death ligand (PD-L) and expression of immune checkpoint molecules PD-1, TIGIT, and TIM3 on functionally exhausted NK cells in TME in CRC. In this review we discuss modalities of cross-talk between tumor cells and NK cells, with regard of EMT-driven changes.

Correlation between High PD-L1 and EMT/Invasive Genes Expression and Reduced Recurrence-Free Survival in Blood-Circulating Tumor Cells from Patients with Non-Muscle-Invasive Bladder Cancer

BACKGROUND

PD-L1 represents a crucial immune checkpoint molecule in the tumor microenvironment, identified as a key target for cancer immunotherapy. A correlation between PD-L1 and EMT-related genes expression in various human cancers has been suggested.

METHODS

By ScreenCell filtration, digital droplet PCR and confocal microscopy analysis, we aimed to investigate the expression of PD-L1 and EMT/invasive genes (TWIST1, ZEB1, VIMENTIN, TIMP2) in circulating tumor cells (CTCs) collected from the blood of non-muscle-invasive bladder cancer (NMIBC) patients, assessing the prognostic value of these biomarkers in the disease. Welchs' test and Mann-Whitney U test, correlation index, Kaplan-Meier, Univariate and Multivariate Cox hazard proportional analysis were used.

RESULTS

Higher PD-L1, TIMP2 and VIM mRNA levels were found in pT1 compared to pTa NMIBC. As evaluated by Kaplan-Meier and Univariate and Multivariate Cox analysis, enhancement of PD-L1, TWIST1 and TIMP2 expression reduces the recurrent free survival in NMIBC patients.

CONCLUSIONS

High PD-L1, TWIST1 and TIMP2 mRNAs mark the recurrent-NMIBC patients and by reducing the RFS represent negative prognostic biomarkers in these patients.

Efficacy and Safety of Programmed Cell Death 1 Inhibitor Monotherapy Versus Chemotherapy as Second-Line Treatment for Advanced Esophageal Cancer: A Meta-analysis and Systematic Review

PURPOSE

With programmed cell death 1 (PD-1) inhibitors approved for second-line treatment of advanced esophageal cancer, immunotherapy and chemotherapy have gradually become the main treatments for second-line treatment of patients with advanced esophageal cancer (AEC). This meta-analysis and systematic review were conducted to evaluate the efficacy and safety of PD-1 inhibitors monotherapy versus chemotherapy in second-line treatment of AEC.

METHODS

Eligible randomized controlled trials were searched in PubMed, Embase, and the Cochrane Library and abstracts presented at the American Society of Clinical Oncology or European Society of Medical Oncology were reviewed to assess the efficacy and tolerability of PD-1/programmed cell death ligand 1 (PD-L1) inhibitors relative to chemotherapy for AEC from January 2016 to October 2020. Patients diagnosed with AEC and progressing after first-line therapy were included in this study. Hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS), risk ratios (RRs) of objective response rate (ORR), and the odds ratios (ORs) of adverse effects (AEs) were calculated.

FINDINGS

The study included 4 randomized controlled trials with 1683 patients. The results indicated that PD-1 inhibitors prolonged the OS (HR = 0.79; 95% CI, 0.71-0.88; P < 0.01) and improved the ORR (RR = 3.00; 95% CI, 2.36-3.82; P = 0.01) but did not improve the PFS (HR = 0.96; 95% CI, 0.76-1.20; P = 0.692) compared with chemotherapy in the second-line treatment of AEC. PD-1 inhibitors alone were associated with a lower incidence of all treatment-related AEs (OR = 0.29; 95% CI, 0.09-0.89; P = 0.03) and grade 3 to 5 treatment-related AEs (OR = 0.26; 95% CI, 0.16-0.44; P < 0.01) versus chemotherapy. PD-1 inhibitors prolonged OS mainly in the following patient groups: male, age <65 years, Eastern Cooperative Oncology Group performance status of 1, or PD-L1 tumor proportion score ≥10%. Asian patients had a longer OS than non-Asian patients (P = 0.01).

IMPLICATIONS

The available evidence indicates that the efficacy and tolerability of PD-1 inhibitors were better than chemotherapy in the second-line treatment of AEC, and the benefiting population of these patients was limited to males, those <65 years of age, those with a Eastern Cooperative Oncology Group performance status of 1, or those with a PD-L1 tumor proportion score ≥10%. Notably, Asian patients receiving immune monotherapy had longer OS than non-Asian patients.

Advances and challenges in the treatment of esophageal cancer

Esophageal cancer (EC) is one of the most common cancers with high morbidity and mortality rates. EC includes two histological subtypes, namely esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). ESCC primarily occurs in East Asia, whereas EAC occurs in Western countries. The currently available treatment strategies for EC include surgery, chemotherapy, radiation therapy, molecular targeted therapy, and combinations thereof. However, the prognosis remains poor, and the overall five-year survival rate is very low. Therefore, achieving the goal of effective treatment remains challenging. In this review, we discuss the latest developments in chemotherapy and molecular targeted therapy for EC, and comprehensively analyze the application prospects and existing problems of immunotherapy. Collectively, this review aims to provide a better understanding of the currently available drugs through in-depth analysis, promote the development of new therapeutic agents, and eventually improve the treatment outcomes of patients with EC.

Thalidomide suppresses angiogenesis and immune evasion via lncRNA FGD5-AS1/miR-454-3p/ZEB1 axis-mediated VEGFA expression and PD-1/PD-L1 checkpoint in NSCLC

BACKGROUND

Non-small cell lung cancer (NSCLC) accounts for about 80-85% of total lung cancer cases. Identifying the molecular mechanisms of anti-tumor drugs is essential for improving therapeutic effects. Herein, we aim to investigate the role of thalidomide in the tumorigenicity of NSCLC.

METHODS

The A549 xenograft nude mouse model was established to explore therapeutic effects of thalidomide. The expression of FGD5-AS1 was evaluated in carcinomatous and paracarcinomatous tissues from NSCLC patients as well as NSCLC cell lines. CCK-8 assay was performed to assess cell viability. The invasive capacity was examined using transwell assay. The tube formation assay was applied to determine cell angiogenesis. Flow cytometry was subjected to validate CD8⁺ T cell activity. The FGD5-AS1/miR-454-3p/ZEB1 regulatory network was analyzed using luciferase reporter, RIP and ChIP assays.

RESULTS

Thalidomide reduced tumor growth and angiogenesis and increased CD8⁺ T cell ratio in a mouse model. Enhanced expression of FGD5-AS1 was positively correlated with the poor survival of NSCLC patients. Knockdown of FGD5-AS1 notably suppressed the proliferation, invasion and angiogenesis of cancer cells as well as the apoptosis of CD8⁺ T cells. Thalidomide targeted FGD5-AS1 to exert its anti-tumor activity in NSCLC. FGD5-AS1 acted as a sponge of miR-454-3p to upregulate ZEB1, thus increasing the expression of PD-L1 and VEGFA. Simultaneous overexpression of FGD5-AS1 and silencing of miR-454-3p reversed thalidomide-mediated anti-tumor effects in NSCLC.

CONCLUSION

Thalidomide inhibits NSCLC angiogenesis and immune evasion via FGD5-AS1/miR-454-3p/ZEB1 axis-mediated regulation of VEGFA expression and PD-1/PD-L1 checkpoint.

Thymoquinone Suppresses the Proliferation, Migration and Invasiveness through Regulating ROS, Autophagic Flux and miR-877-5p in Human Bladder Carcinoma Cells

Bladder carcinoma is among the top 10 most frequently diagnosed cancer types in the world. As a phytochemical active metabolic, thymoquinone (TQ) is extracted from seeds of Nigella sativa, possessing various biological properties in a wide range of diseases. Moreover, the outstanding anti-cancer effect of TQ is attracting increasing attentions. In certain circumstances, moderate autophagy is regarded to facilitate the adaptation of malignant cells to different stressors. Conversely, closely linked with the mitochondrial membrane potential (MMP) loss, the upregulation of intracellular reactive oxygen species (ROS) is reported to activate the cell apoptosis in many cancer types. Furthermore, the vital effects of microRNAs in the pathological processes of cancer cells have also been confirmed by previous studies. The present research confirms that TQ restrains the viability, proliferation, migration and invasion through activating caspase-dependent apoptosis in bladder carcinoma cells, which is mediated by TQ induced ROS increase in bladder carcinoma cells. Furthermore, TQ is proved to block the fusion of autophagosomes and lysosomes, causing the accumulation of autophagosomes and subsequent cell apoptosis. In addition, TQ is also found to initiate the miR-877-5p/PD-L1 axis, which suppresses the epithelial mesenchymal transition (EMT) and invasion of bladder carcinoma cells. Taken together, TQ induces the apoptosis through upregulating ROS level and impairing autophagic flux, and inhibiting the EMT and cell invasion via activating the miR-877-5p/PD-L1 axis in bladder carcinoma cells.

Prognostic Function of Programmed Cell Death-Ligand 1 in Esophageal Squamous Cell Carcinoma Patients Without Preoperative Therapy: A Systematic Review and Meta-Analysis

Background

Studies investigating the correlation between the expression of programmed cell death-ligand 1 (PD-L1) and prognosis in patients with esophageal squamous cell carcinoma (ESCC) not receiving preoperative therapy have increased significantly, but conclusions remain inconclusive. Therefore, this study aimed to determine the association between clinical outcomes and expression of PD-L1 in ESCC patients without preoperative therapy.

Methods

We conducted a comprehensive literature search using four databases up to May 2020. Quality assessment was carried out according to the Newcastle-Ottawa Quality Assessment Scale (NOS). Hazard ratios (HRs) were used to analyze the association between PD-L1 expression with prognosis. Furthermore, we evaluated the correlation between PD-L1 and clinicopathological characteristics using odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Twenty studies (19 publications) comprising 3,677 patients were included in this meta-analysis. We found that the expression of PD-L1 was not related to overall survival (OS, HR: 1.16, 95% CI: 0.94-1.42, p = 0.16) or disease-free survival (DFS, HR: 0.85, 95% CI: 0.66-1.10, p = 0.21) in ESCC. Furthermore, although PD-L1 expression was not significantly associated with sex, degree of differentiation, TNM stage, T stage, lymph node status, smoking, or alcohol use, the merged OR demonstrated that the expression of PD-L1 was higher in older patients compared to younger patients (OR: 1.40, 95% CI: 1.07-1.83, p = 0.01). No obvious publication bias was observed.

Conclusions

Our present study illustrated that PD-L1 expression was not related to poor prognosis of ESCC patients not receiving preoperative therapy, albeit the association only showed a tendency for statistical significance. Notably, PD-L1 expression showed a significant association with age. This meta-analysis had several limitations; therefore, our results need to be verified through further large-scale and prospective studies.

Prognostic value of PD-L1 expression on immune cells or tumor cells for locally advanced esophageal squamous cell carcinoma in patients treated with neoadjuvant chemoradiotherapy

PURPOSE

Programmed death-ligand 1 (PD-L1) expression may influence the prognosis of patients with localized esophageal cancer. The current study compared the prognostic value of PD-L1 expression between tumor cells and immune cells.

METHODS

Archival esophageal tumor tissue samples were collected from patients who received paclitaxel and cisplatin-based neoadjuvant chemoradiotherapy (CRT) for locally advanced esophageal squamous cell carcinoma (ESCC) in three prospective phase II trials. PD-L1 expression on tumor and immune cells was examined immunohistochemically by using the SP142 antibody and scored by two independent pathologists. The association of PD-L1 expression with patient's outcomes was analyzed using a log-rank test and Cox regression multivariate analysis.

RESULTS

A total of 100 patients were included. PD-L1 expression on tumor cells was positive (≥ 1%, TC-positive) in 55 patients; PD-L1 expression on immune cells was high (≥ 5%, IC-high) in 30 patients. TC-positive status was associated with poor overall survival (OS) (HR: 1.63, P = 0.035), whereas IC-high status was associated with improved OS (HR: 0.44, P = 0.0024). Multivariate analysis revealed that TC-positive, IC-high, and performance status were independent prognostic factors for progression-free survival and that IC-high and performance status were independent factors for OS. Furthermore, the combination of IC-high and TC-negative status was associated with the optimal OS, whereas that of TC-positive and IC-low status was associated with the worst OS.

CONCLUSION

PD-L1 expression on tumor and immune cells may have different prognostic value for patients with locally advanced ESCC receiving neoadjuvant CRT. A combination of these two indexes may further improve the prognostic prediction.

Clinicopathological and prognostic values of PD-L1 expression in oesophageal squamous cell carcinoma: a meta-analysis of 31 studies with 5368 patients

Several immune checkpoint inhibitors targeting programmed death ligand 1 (PD-L1)/programmed death 1 have successfully improved the prognosis of oesophageal squamous cell carcinoma (ESCC) with approval in certain countries. However, whether the expression of PD-L1 is associated with the degree of benefit is unclear yet and a unified standard of antibody and cut-off value of PD-L1 detection is also lacking. The current meta-analysis then aimed to explore the association between PD-L1 expression and clinicopathological features as well as prognosis in ESCC.A systematic search on PubMed, Embase, Cochrane Library and Web of Science databases was performed up to 30 March 2021. The correlation between PD-L1 expression and clinicopathological features, as well as prognosis in ESCC, was estimated with the random-effects model.A total of 5368 patients from 31 retrospective studies were enrolled. The overexpression of PD-L1 was significantly associated with lymph node metastasis (OR 1.342, 95% CI 0.995 to 1.809, p=0.050) and distant metastasis (OR 1.516, 95% CI 1.001 to 2.294, p=0.050). The pooled HR showed that PD-L1 overexpression was significantly correlated with poor overall survival (OS) of patients with ESCC (HR 1.306, 95% CI 1.108 to 1.539, p<0.010) but not disease-free survival (DFS) (HR 1.180, 95% CI 0.937 to 1.487, p=0.160). Heterogeneity decreased significantly in subgroup analyses. The overexpression of PD-L1 was associated with poor DFS at the cut-off point of ≥1% (HR 1.642, 95% CI 1.367 to 1.973, p<0.010; I²=0%) and worse OS at the cut-off point of ≥10% (HR 1.575, 95% CI 1.175 to 2.111, p<0.010; I²=0%).The overexpression of PD-L1 was correlated with lymph node and distant metastasis as well as poor survival of ESCC.

Anti-cancer effects of Tranilast: An update

Tranilast (TRN) or (N-3,4 -dimethoxy cinnamoyl]-anthranilic acid) is an analog of a tryptophan metabolite and is identified mainly as an anti-allergic agent with limited side effects. The anti-cancer effects of tranilast either alone or in combination with chemotherapeutic drugs have been evidenced in several pre-clinical studies. The main mechanism of action of tranilast includes targeting and modulation of various signaling and immune regulatory pathways including Transforming growth factor-beta (TGF-β), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphatidylinositol 3-kinase (PI3K), MAP-Kinase (MAPK), Protein kinase B (‎Akt/PKB), c-Jun N-terminal kinase, modulation of cancer stem cells, etc. Most of these pathways are involved in tumor proliferation, invasion, and metastasis and it is postulated that tranilast, with its low toxicity profile and high anti-carcinogenic abilities, can serve as a potential anti-tumorigenic agent. The main aim of this review is to provide updated information on the anti-cancer effects of tranilast and its significance as a therapeutic agent.

Epithelial-to-Mesenchymal Transition in the Light of Plasticity and Hybrid E/M States

Epithelial-to-mesenchymal transition (EMT) is a cellular program which leads to cells losing epithelial features, including cell polarity, cell-cell adhesion and attachment to the basement membrane, while gaining mesenchymal characteristics, such as invasive properties and stemness. This program is involved in embryogenesis, wound healing and cancer progression. Over the years, the role of EMT in cancer progression has been heavily debated, and the requirement of this process in metastasis even has been disputed. In this review, we discuss previous discrepancies in the light of recent findings on EMT, plasticity and hybrid E/M states. Moreover, we highlight various tumor microenvironmental cues and cell intrinsic signaling pathways that induce and sustain EMT programs, plasticity and hybrid E/M states. Lastly, we discuss how recent findings on plasticity, especially on those that enable cells to switch between hybrid E/M states, have changed our understanding on the role of EMT in cancer metastasis, stemness and therapy resistance.

Tumor-derived extracellular vesicles containing microRNA-1290 promote immune escape of cancer cells through the Grhl2/ZEB1/PD-L1 axis in gastric cancer

Gastric cancer (GC) is a highly prevalent malignancy featured by dismal oncological outcomes. Accumulating pieces of evidence have consensus over the therapeutic significance of extracellular vesicles (EVs) and its role in carcinogenesis. Here, we planned to uncover EVs' role in GC by shuttling microRNA-1290 (miR-1290) and to identify the possible molecular mechanism associated with Grhl2, PD-L1, and ZEB1. Grhl2 was under-expressed in GC tissues, exhibiting a negative correlation with PD-L1 expression. In addition, Grhl2 promoted T cell proliferation by down-regulating PD-L1 via inhibiting ZEB1, while miR-1290 was found to negatively regulate Grhl2. EVs were also isolated from GC cells or normal gastric epithelial cells and identified with the presence of EV markers. miR-1290 expression was determined to be enriched in the EVs derived from GC cells and observed to promote the suppressive action of GC cells on T cell activation by up-regulating PD-L1 via the Grhl2/ZEB1 pathway in the co-culture system of GC cells with or without treatment of EVs with T cells. Moreover, we also developed a mouse model of GC and injected the EVs derived from miR-1290-inhibitor-treated GC cells into the tumor-bearing mice for further validation of mechanism in vivo. Intriguingly, the pivotal role of EVs-shuttled miR-1290 as an oncomiR was demonstrated in vivo. Collectively, we found that miR-1290 in EVs secreted from GC cells contributed to immune escape through the Grhl2/ZEB1/PD-L1 axis.

Sarcomatoid hepatocellular carcinoma is distinct from ordinary hepatocellular carcinoma: Clinicopathologic, transcriptomic and immunologic analyses

Sarcomatoid hepatocellular carcinoma (SHCC), which was a rare histological subtype of hepatocellular carcinoma (HCC), is currently subclassified as poorly differentiated HCC because of insufficient evidence to define SHCC as a subtype of HCC. We aimed to assess the feasibility of classifying SHCC as a histological subtype of HCC by comprehensively identifying novel and distinct characteristics of SHCC compared to ordinary HCC (OHCC). Fifteen SHCCs (1.4%) defined as HCC with at least a 10% sarcomatous component, 15 randomly disease-stage-matched OHCCs and 163 consecutive OHCCs were extracted from 1106 HCCs in the Pathology Database (1997-2019) of our hospital. SHCC patients showed poor prognosis, and the tumors could be histologically subclassified into the pleomorphic, spindle and giant cell types according to the subtype of carcinomas with sarcomatoid or undifferentiated morphology in other organs. The transcriptomic analysis revealed distinct characteristics of SHCC featuring the upregulation of genes associated with epithelial-to-mesenchymal transition and inflammatory responses. The fluorescent multiplex immunohistochemistry results revealed prominent programmed death-ligand 1 (PD-L1) expression on sarcomatoid tumor cells and higher infiltration of CD4⁺ and CD8⁺ T cells in SHCCs compared to OHCCs. The density of CD8⁺ T cells in the nonsarcomatous component of SHCCs was also higher than that in OHCCs. In conclusion, the comprehensive analyses in our study demonstrated that SHCC is distinct from OHCC in terms of clinicopathologic, transcriptomic and immunologic characteristics. Therefore, it is reasonable to consider SHCC as a histological subtype of HCC.

Epigenetic modulation combined with PD-1/PD-L1 blockade enhances immunotherapy based on MAGE-A11 antigen-specific CD8+T cells against esophageal carcinoma

Cancer testis antigens (CTAs) are promising targets for T cell-based immunotherapy and studies have shown that certain CT genes are epigenetically depressed in cancer cells through DNA demethylation. Melanoma-associated antigen A11 (MAGE-A11) is a CTA that is frequently expressed in esophageal cancer and is correlated with a poor esophageal cancer prognosis. Consequently, MAGE-A11 is a potential immunotherapy target. In this study, we evaluated MAGE-A11 expression in esophageal cancer cells and found that it was downregulated in several tumor cell lines, which restricted the effect of immunotherapy. Additionally, the specific recognition and lytic potential of cytotoxic T lymphocytes (CTLs) derived from the MAGE-A11 was determined. Specific CTLs could kill esophageal cancer cells expressing MAGE-A11 but rarely lysed MAGE-A11-negative tumor cells. Therefore, induction of MAGE-A11 expression is critical for CTLs recognition and lysis of esophageal cancer cells. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine increased MAGE-A11 expression in esophageal cancer cells and subsequently enhanced the cytotoxicity of MAGE-A11-specific CD8+T cells against cancer cell lines. Furthermore, we found that PD-L1 expression in esophageal cancer cells affected the antitumor function of CTLs. programmed death-1 (PD-1)/PD-L1 blockade could increase the specific CTL-induced lysis of HLA-A2+/MAGE-A11+ tumor cell lines treated with 5-aza-2'-deoxycytidine. These findings indicate that the treatment of tumor cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine augments MAGE-A11 expression in esophageal cancer cells. The combination of epigenetic modulation by 5-aza-2'-deoxycytidine and PD-1/PD-L1 blockade may be useful for T cell-based immunotherapy against esophageal cancer.

Induction Chemotherapy for Locally Advanced Esophageal Cancer

BACKGROUND

Concurrent chemoradiotherapy followed by surgery is the standard treatment for locally advanced esophageal cancer (EC), and the role of induction chemotherapy (IC) remains unclear. We aimed to study if the addition of IC to standard treatment increases the rate of pathologic complete response (pCR).

METHODS

We assembled a retrospective analysis of patients (pts) diagnosed with locally advanced EC and treated with preoperative chemoradiotherapy followed by esophagectomy (CRT+S), preceded or not by IC, between 2009 and 2017. Patients' characteristics, tumor variables, and treatment outcomes were evaluated. The Kaplan-Meier method was used to estimate overall survival and the Cox proportional hazard model to evaluate prognostic factors.

RESULTS

One hundred and three patients were studied, with a median age of 62 years (range 37-84). Seventy-five patients (73%) were male, 67 (65%) had squamous cell carcinoma, and 31 (30%) had adenocarcinoma. Forty-three patients (41.7%) received IC followed by CRT+S (IC+CRT+S). The most frequent IC consisted of paclitaxel and platinum chemotherapy (90%), and the median number of cycles was 2. All patients received CRT+S. Concurrent chemotherapy was a combination of paclitaxel and platinum in 94 patients (91%). There was no statistically significant difference in pCR between the IC group and the standard CRT+S group. The pCR was 41.9% and 46.7% in the IC+CRT+S and CRT+S groups (p = 0.628), respectively. In the multivariate analysis, pCR was an independent prognostic factor for time to treatment failure (TTF) (HR 0.35, p = 0.021), but not for overall survival (OS) (p = 0.863). The factor that significantly affected OS in the multivariate analysis was positive lymph node (HR 5.9, 95%, p = 0.026).

CONCLUSIONS

Our data suggest that the addition of IC to standard CRT + S does not increase the pCR rate in locally advanced EC. No difference in OS was observed between pts. that received or not IC. Regardless of the treatment received, pts. achieving a pCR presented improved TTF.

The therapeutic significance of the novel photodynamic material TPE-IQ-2O in tumors

Combination therapies based on photodynamic therapy (PDT) have received much attention in various cancers due to their strong therapeutic effects. Here, we aimed to explore the safety and effectiveness of a new mitochondria-targeting photodynamic material, TPE-IQ-2O, in combination therapies (combined with surgery or immunotherapy). The safety and effectiveness of TPE-IQ-2O PDT were verified with cytotoxicity evaluation in vitro and a zebrafish xenograft model in vivo, respectively. The effectiveness of TPE-IQ-2O PDT combined with surgery or immune checkpoint inhibitors (ICIs) was verified in tumor-bearing mice. Small animal in vivo imaging, immunohistochemistry, and flow cytometry were used to determine the underlying mechanism. TPE-IQ-2O PDT can not only reduce tumor recurrence in surgical treatment but also effectively improve the response to ICIs in immunotherapy without obvious toxicity. It was also found to ameliorate the immunosuppressive tumor microenvironment and promote the antitumor immunity induced by ICIs by increasing CD8⁺ tumor-infiltrating lymphocyte accumulation. Thus, TPE-IQ-2O PDT is a safe and effective antitumor therapy that can be combined with surgery or immunotherapy.

The clinicopathological significance and prognostic value of programmed death-ligand 1 in prostate cancer: a meta-analysis of 3133 patients

Background: Programmed death-ligand 1 (PD-L1) is considered an adverse factor predicting poor prognosis in various cancers, but the significance of PD-L1 expression for the prognosis of prostate cancer (PCa) is still unclear. We aimed to investigate the clinicopathological significance and prognostic value of PD-L1 expression in PCa.

Methods: Studies were retrieved from PubMed, Web of Science, Cochrane Library and Embase before March 23, 2020. Odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were obtained to assess the results. Begg’s test was applied to evaluate publication bias.

Results: Fourteen studies involving 3133 cases were analyzed. The pooled data showed that both PD-L1 protein expression and PD-L1 DNA methylation (mPD-L1) were negatively associated with biochemical recurrence-free survival, with HRs of 1.67 (95% CI = 1.38-2.06, p < 0.001) and 2.23 (95% CI = 1.51-3.29, p < 0.001), respectively. In addition, PD-L1 overexpression was significantly related to advanced tumor stage (OR = 1.40, 95% CI= 1.13-1.75, p = 0.003), positive surgical margin (OR = 1.36, 95% CI = 1.03-1.78, p = 0.028), higher Gleason score (OR = 1.81, 95% CI = 1.35-2.42, p < 0.001) and androgen receptor positivity (OR = 2.20, 95% CI = 1.61-3.01, p < 0.001), while no significant correlation with age (p = 0.122), preoperative PSA (p = 0.796) or nodal status (p = 0.113) was observed.

Conclusions: The study revealed that high expression of PD-L1 was related to unfavorable prognosis and advanced clinicopathological factors in PCa patients.

Selected updates in molecular and genomic pathology of esophageal cancer

Recent years have seen rapid advances in the field of molecular and genomic pathology that have not only improved understanding of esophageal carcinogenesis and tumor immune environment in general but also have reshaped pathology practice and clinical management. In this article, we provide updates on three topics (1) human epidermal growth factor receptor 2, the first and most important biomarker in targeted therapy of esophageal cancer; (2) programmed death 1/programmed death ligand 1, recent biomarkers that have shown promise in treating both esophageal adenocarcinoma and esophageal squamous cell carcinoma; and (3) human papillomavirus involvement in esophageal carcinogenesis, one of the most debated topics in the field, discussed here with a renewed understanding from recent genomic and molecular data.

Role of PD-L1 Expression during the Progression of Submucosal Gastric Cancer

INTRODUCTION

Programmed death-ligand 1 (PD-L1) expression is a prognostic marker for gastric cancer that correlates with tumor diameter and depth of penetration. But the role of PD-L1 and mechanism(s) employed in the initial phase of invasion in early gastric cancer is yet to be understood.

OBJECTIVE

This study aims to elucidate the role of PD-L1 during the progression of gastric cancer, specifically invading the submucosa beyond the lamina muscularis mucosa.

METHODS

Using 107 patients with pathological submucosal gastric cancer, we determined the expression of PD-L1 based on the staining of the cell membrane or cytoplasm of tumor cells in the central and invasive front of the tumor. Samples were categorized into 3 groups based on the intensity of PD-L1 expression. CD8+ lymphocytes expressing PD-1 and CD163+ macrophages were used to determine the number of cell nuclei at the invasive front, similar to PD-L1. CMTM6 levels were determined and used to stratify samples into 3 groups.

RESULTS

PD-L1 expression was higher in the invasive front (26.2%) than in the central portion of the tumors (7.4%; p < 0.001). Moreover, lymphatic and vascular invasion were more frequently observed in samples with high levels of PD-L1 (lymphatic invasion: 60.7 vs. 35.4%, p = 0.0026, and vascular invasion: 39.3 vs. 16.5%, p = 0.0018). There was no correlation between PD-L1 expression and the levels of PD-1, CD8, CD163, and CMTM6.

CONCLUSIONS

PD-L1-expressing cancer cells at the invasive front of gastric cancer influence the initial stages of tumor invasion and lymphovascular permeation in early-stage gastric cancers. Immune checkpoint signaling may be the driving force in the invasive front during the invasion of the submucosa beyond the lamina muscularis mucosa.

Transforming Growth Factor-β: A Multifunctional Regulator of Cancer Immunity

Transforming growth factor-β (TGF-β) was originally identified as an anti-tumour cytokine. However, there is increasing evidence that it has important roles in the tumour microenvironment (TME) in facilitating cancer progression. TGF-β actively shapes the TME via modulating the host immunity. These actions are highly cell-type specific and complicated, involving both canonical and non-canonical pathways. In this review, we systemically update how TGF-β signalling acts as a checkpoint regulator for cancer immunomodulation. A better appreciation of the underlying pathogenic mechanisms at the molecular level can lead to the discovery of novel and more effective therapeutic strategies for cancer.

Transforming Growth Factor-β: A Multifunctional Regulator of Cancer Immunity

Simple Summary

Transforming growth factor beta (TGF-β) is a multifunctional cytokine that can restrict cancer onset but also promote cancer progression at late stages of cancer. The ability of TGF-β in producing diverse and sometimes opposing effects relies on its potential to control different cellular signalling and gene expression in distinct cell types, and environmental settings. The tumour promoting role of TGF-β is primarily mediated through its effects on the local tumour microenvironment (TME) of the cancer cells. In this review, we discuss the most recent research on the role and regulation of TGF-β, with a specific focus on its functions on promoting cancer progression through targeting different immune cells in the TME as well as its therapeutic perspectives.

Abstract

Transforming growth factor-β (TGF-β) was originally identified as an anti-tumour cytokine. However, there is increasing evidence that it has important roles in the tumour microenvironment (TME) in facilitating cancer progression. TGF-β actively shapes the TME via modulating the host immunity. These actions are highly cell-type specific and complicated, involving both canonical and non-canonical pathways. In this review, we systemically update how TGF-β signalling acts as a checkpoint regulator for cancer immunomodulation. A better appreciation of the underlying pathogenic mechanisms at the molecular level can lead to the discovery of novel and more effective therapeutic strategies for cancer.

Zeb1 expression by tumor or stromal cells is associated with spatial distribution patterns of CD8+ tumor-infiltrating lymphocytes: a hypothesis-generating study on 113 triple negative breast cancers

Spatial organization of tumor microenvironment (TME) may influence tumor response to immunomodulatory therapies. Zeb1 is a driver of epithelial-mesenchymal transition, with several roles in immune cell development, however its role in shaping of the immune TME is not fully explored. We conducted a pre-multiplex spatial analysis study to verify whether Zeb1 influences spatial distribution of tumor-infiltrating lymphocytes (TILs) in triple negative breast cancer (TNBC). We applied single and double immunohistochemistry to analyze spatial relationships between CD8+, FoxP3+ and CD20+ tumor-infiltrating lymphocytes (TILs) and the cells expressing Zeb1 in formalin-fixed, paraffin-embedded surgical specimens of 113 TNBCs. 15.5% of cases had Zeb1+ tumor cells and 72.8% of cases had stroma rich in Zeb1+ cells. Low density of intratumoral CD8+ TILs was observed in almost all TNBCs with high or moderate Zeb1+ expression in tumor cells (22/23 cases, 95.6%), and in 90.4% of TNBCs (75/83 cases) with stroma rich in Zeb1+ cells. On the other side, a majority of TNBCs with stroma rich in Zeb1+ cells had high density of stromal CD8+ TILs (55/83 cases, 66.3%). These associations were not observed between Zeb1-expressing cells and FoxP3+ or CD20+ TILs. This in situ analysis showed specific spatial relationship between tumor or stromal Zeb1+ cells and CD8+ TILs, which need to be validated in other cohorts. Zeb1 was highlighted both as a marker of tumor cell EMT and of tumor stroma richness in mesenchymal cells. Several hypotheses about causes of the observed relationship between Zeb1 and TILs are generated and the approaches to verify them discussed. Zeb1 is worth further investigation as a potential biomarker of intratumor immunosuppression of TNBC and of its response to immunotherapies.

Epithelial-to-mesenchymal transition and its association with PD-L1 and CD8 in thyroid cancer

Programmed cell death-ligand 1 (PD-L1) has recently been shown to play a role in the regulation of epithelial-to-mesenchymal transition (EMT); however, the relationship between PD-L1 expression, EMT and the inflammatory tumour microenvironment has yet to be investigated in thyroid cancer. To address this issue, we examined the expression of CD8, PD-L1 and the EMT markers E-cadherin and vimentin in a cohort of 74 papillary thyroid cancer (PTC) patients and investigated the association of these with clinicopathologic characteristics and disease-free survival (DFS). The relationship between PD-L1 and EMT was further examined in three thyroid cancer cell lines via Western blot and live cell imaging. In order to expand our in vitro findings, the normalised gene expression profiles of 516 thyroid cancer patients were retrieved and analysed from The Cancer Genome Atlas (TCGA). PD-L1 positivity was significantly higher in PTC patients exhibiting a mesenchymal phenotype (P = 0.012). Kaplan-Meier analysis revealed that PD-L1 (P = 0.045), CD8 (P = 0.038) and EMT status (P = 0.038) were all significant predictors for DFS. Sub-analysis confirmed that the poorest DFS was evident in PD-L1 positive patients with EMT features and negative CD8 expression (P < 0.0001). IFN-γ treatment induced upregulation of PD-L1 and significantly promoted an EMT phenotype in two thyroid cancer cell lines. Our findings suggest that PD-L1 signalling may play a role in stimulating EMT in thyroid cancer. EMT, CD8 and PD-L1 expression may serve as valuable predictive biomarkers in patients with PTC.

Spatial and Temporal Changes in PD-L1 Expression in Cancer: The Role of Genetic Drivers, Tumor Microenvironment and Resistance to Therapy

Immunotherapies blocking immune inhibitory receptors programmed cell death-1 (PD-1) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) on T-cells have dramatically improved patient outcomes in a range of advanced cancers. However, the lack of response, and the development of resistance remain major obstacles to long-term improvements in patient outcomes. There is significant interest in the clinical use of biomarkers to improve patient selection, and the expression of PD-1 ligand 1 (PD-L1) is often reported as a potential biomarker of response. However, accumulating evidence suggests that the predictive value of PD-L1 expression in tumor biopsies is relatively low due, in part, to its complex biology. In this review, we discuss the biological consequences of PD-L1 expression by various cell types within the tumor microenvironment, and the complex mechanisms that regulate PD-L1 expression at the genomic, transcriptomic and proteomic levels.

Immune checkpoint inhibitors for esophageal squamous cell carcinoma: a narrative review

Esophageal cancer (EC) has the seventh highest incidence and the sixth highest mortality rate of any type of cancer worldwide. In China, esophageal squamous cell carcinoma (ESCC) accounts for more than 95% of EC patients. The main treatment for EC patients is surgery and/or chemoradiotherapy (CRT). A large proportion of EC patients are already at an advanced stage of the disease by the time they are diagnosed. In these cases, CRT is left as the only treatment choice, and the treatment outcome is poor. Immune checkpoint inhibitors (ICIs) can improve clinical response and patient survival of patient with many types of tumors through reactivating antitumor immune response. The study of ICIs in ESCC is relative delayed compared with that in other solid tumors. Recent results from clinical trials have demonstrated the safety and efficacy of ICIs either alone or combined with chemotherapy or chemoradiotherapy in ESCC patients. Accumulated evidences also have shown the improved treatment outcome was associated with PD-L1 expression, tumor DNA instability-induced tumor mutational burden (TMB), and drawing lymphocytes into the tumor. Based on these findings, ICIs combined with CRT or radiotherapy (RT) are the focus of ongoing studies. This review will summarize the recent progress in this field, especially the mechanism of ICIs used in ESCC, their clinical efficacy and toxicities, and potential biomarkers.

RAD51 Expression as a Biomarker to Predict Efficacy of Preoperative Therapy and Survival for Esophageal Squamous Cell Carcinoma: A Large-cohort Observational Study (KSCC1307)

OBJECTIVE

The aim of this study is to identify biomarkers that predict efficacy of preoperative therapy and survival for esophageal squamous cell carcinoma (ESCC).

BACKGROUND

It is essential to improve the accuracy of preoperative molecular diagnostics to identify specific patients who will benefit from the treatment; thus, this issue should be resolved with a large-cohort, retrospective observational study.

METHODS

A total of 656 patients with ESCC who received surgery after preoperative CDDP + 5-FU therapy, docetaxel + CDDP + 5-FU therapy or chemoradiotherapy (CRT) were enrolled. Immunohistochemical analysis of TP53, CDKN1A, RAD51, MutT-homolog 1, and programmed death-ligand 1 was performed with biopsy samples obtained before preoperative therapy, and expression was measured by immunohistochemistry.

RESULTS

In all therapy groups, overall survival was statistically separated by pathological effect (grade 3 > grade 2 > grade 0, 1, P < 0.0001). There was no correlation between TP53, CDKN1A, MutT-homolog 1, programmed death-ligand 1 expression, and pathological effect, whereas the proportion of positive RAD51 expression (≥50%) in cases with grade 3 was lower than that with grade 0, 1, and 2 (P = 0.022). In the CRT group, the survival of patients with RAD51-positive tumor was significantly worse than RAD51-negative expressors (P = 0.0119). Subgroup analysis of overall survival with respect to positive RAD51 expression indicated preoperative chemotherapy (CDDP + 5-FU or docetaxel + CDDP + 5-FU) was superior to CRT.

CONCLUSIONS

In ESCC, positive RAD51 expression was identified as a useful biomarker to predict resistance to preoperative therapy and poor prognosis in patients who received preoperative CRT. Administration of preoperative chemotherapy may be warranted for patients with positive RAD51 expression.