Immunotherapy in colorectal cancer

The neoadjuvant immunotherapy for non-metastatic mismatch repair-deficient colorectal cancer: a systematic review

Background

Immunotherapy has become the first-line treatment for metastatic mismatch repair deficient (dMMR) colorectal cancer. The efficacy and safety of neoadjuvant immunotherapy for the treatment of non-metastatic dMMR colorectal cancer remain unclear. In this article, we explore the clinical effect and safety of neoadjuvant immunotherapy for non-metastatic dMMR colorectal cancer.

Methods

We collected clinical data from the databases (PubMed, Wanfang Embase, Cochrane Library, and China National Knowledge Infrastructure databases) up to November 2024. The primary outcomes of major pathological response (MPR), pathological complete response (pCR), and other outcomes were analyzed for the final results. The secondary outcomes (pCR rates for the subgroups) were also analyzed.

Results

We included 21 articles with 628 non-metastatic dMMR colorectal cancers. A pCR was found in 320/480 (66.6%) patients [effect size (ES): 0.70, 95% CI: 0.66 to 0.74] with the fixed-effects model and little heterogeneity. A MPR was found in 388/452 (85.8%) patients (ES: 0.86, 95% CI: 0.81 to 0.91) with the fixed-effects model and little heterogeneity. In the subgroup analysis, pCR rates were similar in the T1-T3 group and T4a-T4b group in the fixed-effects model with minimal heterogeneity (OR: 0.76, 95% CI: 0.48 to 1.22). The pCR rates were similar in the colon cancer group and rectal cancer group in the fixed-effects model with minimal heterogeneity (OR: 1.41, 95% CI: 0.39 to 5.12). Similar pCR rates were found in the immune monotherapy group and immune therapy plus chemotherapy group (OR: 0.74, 95% CI: 0.26 to 2.10) with the fixed-effects model and little heterogeneity.

Conclusion

Neoadjuvant immunotherapy achieves high rates of pCR and MPR for non-metastatic dMMR colorectal cancer. For locally advanced T4 stage dMMR colorectal cancer, neoadjuvant immunotherapy can still achieve good pCR rates. Neoadjuvant immune monotherapy can achieve good pCRs rates, avoiding the toxic side effects caused by combined dual immunotherapy and chemo(radio)therapy. Neoadjuvant immunotherapy could be another treatment option for non-metastatic dMMR colorectal cancer.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024594173.

Overcoming common emerging barriers to effective neoadjuvant immunotherapies

INTRODUCTION

Neoadjuvant immunotherapy has rapidly evolved as a novel approach in oncology, reshaping the standard treatment for several malignancies, including melanoma, lung, bladder, colorectal, and breast cancer. While it has an acceptable safety profile, challenges persist due to the complexity of the tumor microenvironment (TME), immune evasion, T-cell exhaustion, and identification of biomarkers. Addressing these issues is critical for optimizing treatment regimens, minimizing immune-related adverse events, and ensuring successful clinical integration.

AREAS COVERED

This review explores current research on neoadjuvant immunotherapy, emphasizing its impact on standard of care treatment, efficacy, safety, and clinical challenges. A literature search was conducted using PubMed and ClinicalTrials.gov for studies published in the last 5 years. Ongoing research aims to enhance the efficacy of neoadjuvant immunotherapy, identify resistance mechanisms, and broaden indications. Current clinical trials focus on biomarker-driven patient selection, refining immune response modulation through combination strategies, and developing evidence-based protocols for implementation into routine oncology practice.

EXPERT OPINION

Neoadjuvant immunotherapeutic options have rapidly changed the oncological treatment landscape in only a few years, and this treatment paradigm has quickly become a new standard of care in multiple solid tumors. With continued clinical investigation, neoadjuvant immunotherapy has the dramatic potential to further advance cancer care.

Nano-Armed Limosilactobacillus reuteri for Enhanced Photo-Immunotherapy and Microbiota Tryptophan Metabolism against Colorectal Cancer

Despite being a groundbreaking approach to treating colorectal cancer (CRC), the efficacy of immunotherapy is significantly compromised by the immunosuppressive tumor microenvironment and dysbiotic intestinal microbiota. Here, leveraging the superior carrying capacity and innate immunity-stimulating property of living bacteria, a nanomedicine-engineered bacterium, LR-S-CD/CpG@LNP, with optical responsiveness, immune-stimulating activity, and the ability to regulate microbiota metabolome is developed. Immunoadjuvant (CpG) and carbon dot (CD) co-loaded plant lipid nanoparticles (CD/CpG@LNPs) are constructed and conjugated to the surface of Limosilactobacillus reuteri (LR) via reactive oxygen species (ROS)-responsive linkers. The inherent photothermal and photodynamic properties of oral CD/CpG@LNPs induce in situ cytotoxic ROS generation and immunogenic cell death of colorectal tumor cells. The generated neoantigens and the released CpG function as a potent in situ vaccine that stimulates the maturation of immature dendritic cells. The mature dendritic cells and metabolites secreted by LR subsequently facilitated the tumor infiltration of cytotoxic T lymphocytes to eradicate colorectal tumors. The further in vivo results demonstrate that the photo-immunotherapy and intestinal microbial metabolite regulation of LR-S-CD/CpG@LNPs collectively suppressed the growth of orthotopic colorectal tumors and their liver metastases, presenting a promising avenue for synergistic treatment of CRC via the oral route.

PFAS promotes colorectal cancer progression via regulating RIG-I-mediated innate immune signalling

OBJECTIVE

Phosphoribosylformylglycinamidine synthase (PFAS) is a critical enzyme in de novo synthesis of purine. Innate immunity recognizes tumor derived damage-associated molecular patterns (DAMPs) and initiates the anti-tumor adaptive responses. While the function of PFAS catalyzed de novo synthesis of purine is well proved, its effect on innate immune evasion in cancer is unclear and needs to be further explored. The purpose of this study was to investigate the specific mechanisms by which PFAS inhibits RIG-I receptor (RLR) -mediated NF-κB axis in CRC.

MATERIALS AND METHODS

quantitative real-time PCR (qRT-PCR), Immunohistochemical (IHC) staining and western blotting were conducted to study the expression of PFAS in CRC tissues. Survival analysis, COX regression analysis and receiver operating characteristic (ROC) curve analysis were respectively conducted to assess correlation between the PFAS expression and clinicopathological characteristics, investigate the percent survival based on PFAS level in different clinical CRC groups, identify factors influencing the prognosis of CRC, and illustrate the diagnostic ability of PFAS in CRC patients. Furthermore, the CCK8 and transwell assays were carried out to study CRC cell function affected by PFAS. Mechanistically, plaque assay was used to assess the regulation of PFAS on innate immune signalling. The inhibition of PFAS on RIG-I-mediated innate immune signalling was further investigated by qRT-PCR and reporter assays in thepresence of lentiviral-mediated PFAS stably knocking down and stably overexpressing. Lastly, the interaction between PFAS and RIG-I was verified by co-immunoprecipitation assay.

RESULTS

The expression of PFAS in CRC tissue was higher than in adjacent normal colorectal tissue. The level of PFAS expression was significantly associated with stage-AJCC, regional lymph nodes metastasis and recurrence in CRC. Low expression of gene PFAS caused better survival than high expression in CRC patients. PFAS could be considered as an independent prognostic risk factor of CRC. PFAS promote cell proliferation and invasion of CRC cell lines. According to ROC curve analysis, PFAS could be used as a diagnostic biomarker in CRC. Mechanistically, PFAS inhibit interferon-β (IFN-β) gene and interferon-stimulated gene 56 (ISG56) expression. Furthermore, we confirmed that PFAS target RIG-I to inhibit RIG-I-mediated innate immune signalling.

BATF promotes tumor progression and association with FDG PET-derived parameters in colorectal cancer

PURPOSE

The purpose of the study was to evaluate the expression and function of basic leucine zipper ATF-like transcription factor (BATF) in colorectal cancer (CRC), and its correlation with 2-deoxy-2[18F]fluoro-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) parameters.

METHODS

The TIMER database, GEPIA database, TCGA, and GEO database were used to analyze the expression profile of BATF in human cancers. The reverse transcription‑quantitative PCR and western blot analyses were used to evaluate the mRNA level and protein expression in different CRC cell lines. The expression of BATF in SW620 and HCT116 cells was silenced and cell counting kit-8 assays and clonogenic assay were utilized to evaluate the role of BATF in CRC proliferation. The expression of tumor BATF and glucose transporter 1 (GLUT-1) were examined using immunohistochemical tools in 37 CRC patients undergoing preoperative 18F-FDG PET/CT imaging. The correlation between the PET/CT parameters and immunohistochemical result was evaluated.

RESULTS

In database, BATF was highly expressed in pan-cancer analyses, including CRC, and was associated with poor prognosis in CRC. In vitro, the results showed that knocking down of BATF expression could inhibit the proliferation of SW620 and HCT116 cells. In CRC patients, BATF expression was upregulated in tumor tissues compared with matched para-tumoral tissues, and was related with gender and Ki-67 levels. BATF expression was positively related to GLUT-1 expression and PET/CT parameters, including tumor size, maximum standard uptake value, metabolic tumor volume, and total lesion glycolysis. The multiple logistic analyses showed that SUVmax was an independent predictor of BATF expression. With 15.96 g/cm3 as the cutoff, sensitivity was 85.71%, specificity 82.61%, and area-under-the-curve 0.854.

CONCLUSION

BATF may be an oncogene associated with 18F-FDG PET/CT parameters in CRC. SUVmax may be an independent predictor of BATF expression.

Exploration of the Molecular Mechanism of Curcuma aromatica Salisb's Anticolorectal Cancer Activity via the Integrative Approach of Network Pharmacology and Experimental Validation

Curcuma aromatica Salisb (Cur), a well-known herbal medicine, has a wide spectrum of anti-inflammatory, anticarcinogenic, and antioxidant activities. However, the roles of its active compounds and potential mechanisms in colorectal cancer remain unknown. This research utilized network pharmacology and experimental validation to explore the possible mechanisms by which Cur protects against colorectal cancer. The active compounds of Cur and related genes for colorectal cancer were obtained from public databases. The DrugBank database was used to search for anticolorectal cancer drugs licensed through the FDA and their targets, and a "drug-component-target" relationship network was created using the Cytoscape program. The String database produced the PPI network. The ability of these active ingredients to bind to core targets was confirmed by molecular docking using AutoDock Vina. Cell and animal experiments were then carried out. A total of 274 targets were obtained from Cur, 49 of which were potential therapeutic targets. Four key targets, PTGS2, AKT1, TP53, and estrogen receptor 1 (ESR1), were screened via the PPI network and the FDA drug-target network. Molecular docking results revealed that Cur had strong binding abilities to these targets. In vivo and in vitro experiments demonstrated that Cur suppressed the development of colorectal cancer by regulating its targets (PTGS2, AKT1, TP53, and ESR1), which play crucial roles in promoting apoptosis and suppressing cell proliferation, migration, and invasion. Collectively, Cur protects against colorectal cancer by regulating the AKT1/PTGS2/ESR1 and P53 pathways, which lays the groundwork for further research and clinical applications of Cur in colorectal cancer therapy.

Near-infrared fluorescence tattooing: a new approach for endoscopic marking of tumors in minimally invasive colorectal surgery using a persistent near-infrared marker

INTRODUCTION

Intraoperative accurate localization of tumors in the lower gastrointestinal tract is essential to ensure oncologic radicality. In minimally invasive colon surgery, tactile identification of tumors is challenging due to diminished or absent haptics. In clinical practice, preoperative endoscopic application of a blue dye (ink) to the tumor site has become the standard for marking and identification of tumors in the colon. However, this method has the major limitation that accidental intraperitoneal spillage of the dye can significantly complicate the identification of anatomical structures and surgical planes. In this work, we describe a new approach of NIR fluorescent tattooing using a near-infrared (NIR) fluorescent marker instead of a blue dye (ink) for endoscopic tattooing.

METHODS

AFS81x is a newly developed NIR fluorescent marker. In an experimental study with four domestic pigs, the newly developed NIR fluorescent marker (AFS81x) was used for endoscopic tattooing of the colon. 7-12 endoscopic submucosal injections of AFS81x were placed per animal in the colon. On day 0, day 1, and day 10 after endoscopic tattooing with AFS81x, the visualization of the fluorescent markings in the colon was evaluated during laparoscopic surgery by two surgeons and photographically documented.

RESULTS

The detection rate of the NIR fluorescent tattoos at day 0, day 1, and day 10 after endoscopic tattooing was 100%. Recognizability of anatomical structures during laparoscopy was not affected in any of the markings, as the markings were not visible in the white light channel of the laparoscope, but only in the NIR channel or in the overlay of the white light and the NIR channel of the laparoscope. The brightness, the sharpness, and size of the endoscopic tattoos did not change significantly on day 1 and day 10, but remained almost identical compared to day 0.

CONCLUSION

The new approach of endoscopic NIR fluorescence tattooing using the newly developed NIR fluorescence marker AFS81x enables stable marking of colonic sites over a long period of at least 10 days without compromising the recognizability of anatomical structures and surgical planes in any way.

Identification of necroptosis-related lncRNAs for prognosis prediction and screening of potential drugs in patients with colorectal cancer

BACKGROUND

Tumor recurrence and metastasis lead to a poor prognosis in colorectal cancer (CRC). Necroptosis is closely related to the tumor microenvironment (TME) and affects tumor recurrence and metastasis. We aimed to stratify CRC patients according to necroptosis-related long noncoding RNAs (lncRNAs), which can be used to not only evaluate prognosis and improve precision medicine in clinical practice but also screen potential immunotherapy drugs.

AIM

To stratify CRC patients according to necroptosis-related lncRNAs (NRLs), which can be used to not only evaluate prognosis and improve precision medicine in clinical practice but also screen potential immunotherapy drugs.

METHODS

LncRNA expression profiles were collected from The Cancer Genome Atlas. NRLs were identified by coexpression analysis. Cox regression analysis identified a NRL signature. Then, the value of this signature was comprehensively and multidimensionally evaluated, and its reliability for CRC prognosis prediction was assessed with clinical CRC data and compared with that of six other lncRNA signatures. Gene set enrichment analysis, TME analysis and half-maximal inhibitory concentration (IC₅₀) prediction were also performed according to the risk score (RS) of the signature.

RESULTS

An 8-lncRNA signature significantly associated with overall survival (OS) was constructed, and its reliability was validated with clinical CRC data. Most of the areas under the receiver operating characteristic curves (AUCs) values for 1-, 3- and 5-year OS for this signature were higher than those for the other six lncRNA signatures. OS, disease-specific survival and the progression-free interval were all significantly poorer in the high-risk group. The RS of the signature showed good concordance with the predicted prognosis, with AUCs for 1-, 3- and 5-year OS of 0.79, 0.81 and 0.77, respectively. Additionally, the calibration plots for this signature combined with clinical factors showed that this combination could effectively improve the ability to predict OS. The RS was correlated with tumor stage, lymph node metastasis and distant metastasis. Most of the enriched Kyoto Encyclopedia of Genes and Genomes and Gene Ontology terms were tumor metastasis-related pathways in the high-risk group; these patients showed greater infiltration of immunosuppressive cells, such as cancer-associated fibroblasts, hematopoietic stem cells and M2 macrophages, but less infiltration of infiltrating antitumor effector immune cells, such as cluster of differentiation 8⁺ T cells and regulatory T cells (Tregs). We explored additional potential immune checkpoint genes and potential immunotherapeutic and chemotherapeutic drugs with relatively low IC₅₀ values.

CONCLUSION

We identified an NRL signature with strong fidelity that could stably predict prognosis and might be an indicator of the TME of CRC. Furthermore, additional potential immunotherapeutic and chemotherapeutic drugs were explored.

m5C regulator-mediated methylation modification phenotypes characterized by distinct tumor microenvironment immune heterogenicity in colorectal cancer

The RNA 5-methylcytosine (m5C) modification has been demonstrated to be an important epigenetic regulator and to impact colorectal cancer (CRC) progression. However, the potential roles of m5C modification in immune cell infiltration in the CRC tumor microenvironment (TME) remain unknown. The m5C modification phenotypes were comprehensively evaluated based on 14 m5C regulators in a meta-CRC cohort of 1792 patients and systematically correlated with the m5C modification phenotypes, immune cell infiltration characteristics and known biological processes. The m5Cscore model was constructed by principal component analysis (PCA) algorithms to quantify the m5C modification phenotypes of individual CRC samples and was used to predict the immunotherapy response. We identified three m5C modification phenotypes associated with distinct clinical outcomes and biological processes among the 1792 meta-CRC patients. Three phenotypes with a highly consistent TME landscape and characteristics were revealed: immune excluded, immune desert and immune inflammation. The meta-CRC patients were divided into high and low m5Cscore subgroups based on the m5Cscore. The m5Cscore was confirmed to have a negative correlation with infiltrating immune cells and PD-L1 expression and a positive correlation with tumor mutation burden (TMB), mutation rate and microsatellite instability (MSI) score. Moreover, patients in the low m5Cscore group had better immunotherapy responses and significant durable survival benefits in independent anti-PD-1/L1 immunotherapy cohorts for the immune checkpoint inhibitor (ICI) therapeutic strategy. This study revealed that m5C modification plays a crucial role in TME composition and complexity. Comprehensive evaluation of the m5C modification phenotypes of individual patients will enhance our understanding of TME characteristics and promote the application of more appropriate and personalized treatment strategies.

Establishment of a gastric cancer cell line with high microsatellite instability, OCUM-13, derived from Borrmann type-2 primary tumor

Gastric cancer (GC) with microsatellite instability (MSI) has been reported to be sensitive to immunotherapy, however some of GC cases with MSI remain resistant to immunotherapy. Cancer cell lines showing MSI might be useful for the analysis of mechanisms of immunotherapy, while only a few GC cell lines with MSI are available so far. In this study, we established a unique GC cell line with MSI, OCUM-13, from a primary GC with abundant tumor-infiltrating lymphocytes. MSI assay indicated that OCUM-13 cells as well as the primary tumor showed a band shift in more than 3 of 5 microsatellite loci, suggesting that OCUM-13 did have high MSI. The subcutaneous inoculation of OCUM-13 cells into mice performed tumor formation. Insulin-like growth factor 1 receptor inhibitor decreased the growth of OCUM-13 cells. The newly established cell line with MSI, OCUM-13, might be useful for the analysis of cancer therapy for GC with MSI.

Identifying and clinically validating biomarkers for immunotherapy in colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is a leading cause of death. For three decades, chemotherapy with or without targeted therapy (provided before or after tumor resection surgery) has been the standard treatment for patients with CRC. Biomarkers are key tools for performing early detection, prognostication, and survival and treatment response predictions. Notably, immune checkpoint inhibitors (ICIs) have transformed prognoses for solid tumors (including CRC).

AREA COVERED

Although immunotherapy has developed considerably, it is only effective for a small number of microsatellite instability-high (MSIH) cancer cases; such cases represent only 5% of metastatic CRC (mCRC) cases, which are characterized by an immune-inflamed microenvironment that can be rewired against cancer cells through ICI administration. Immunotherapy research is gradually uncovering the mechanism underlying immune resistance in patients with CRC and discovering new biomarkers. For example, studies have clinically validated the associations of deficient mismatch repair system/microsatellite instability, tumor mutation burden, programmed death ligand 1 expression, and polymerase epsilon with CRC in patients undergoing immunotherapy.

EXPERT OPINIONS

Clinical trials documenting the effect of immune checkpoints were performed to produce long-lasting effects for patients with mCRC. Consequently, therapeutic decision-making models are further refined by the inclusion of powerful molecular biomarkers in patients with CRC.

DNA methylation-based patterns for early diagnostic prediction and prognostic evaluation in colorectal cancer patients with high tumor mutation burden

Background

Immune checkpoint inhibitor (ICI) therapy has proven to be a promising treatment for colorectal cancer (CRC). We aim to investigate the relationship between DNA methylation and tumor mutation burden (TMB) by integrating genomic and epigenetic profiles to precisely identify clinical benefit populations and to evaluate the effect of ICI therapy.

Methods

A total of 536 CRC tissues from the Cancer Genome Atlas (TCGA) with mutation data were collected and subjected to calculate TMB. 80 CRC patients with high TMB and paired normal tissues were selected as training sets and developed the diagnostic and prognostic methylation models, respectively. In the validation set, the diagnostic model was validated in our in-house 47 CRC tissues and 122 CRC tissues from the Gene Expression Omnibus (GEO) datasets, respectively. And a total of 38 CRC tissues with high TMB from the COLONOMICS dataset verified the prognostic model.

Results

A positive correlation between differential methylation positions and TMB level was observed in TCGA CRC cohort (r=0.45). The diagnostic score that consisted of methylation levels of four genes (ADHFE1, DOK6, GPR75, and MAP3K14-AS1) showed high diagnostic performance in the discovery (AUC=1.000) and two independent validation (AUC=0.946, AUC=0.857) datasets. Additionally, these four genes showed significant positive correlations with NK cells. The prognostic score containing three genes (POU3F3, SYN2, and TMEM178A) had significantly poorer survival in the high-risk TMB samples than those in the low-risk TMB samples (P=0.016). CRC patients with low-risk scores combined with TMB levels represent a favorable survival.

Conclusions

By integrating analyses of methylation and mutation data, it is suggested that DNA methylation patterns combined with TMB serve as a novel potential biomarker for early screening in more high-TMB populations and for evaluating the prognostic effect of CRC patients with ICI therapy.

A CD8+ T cell-associated immune gene panel for prediction of the prognosis and immunotherapeutic effect of melanoma

Background

Skin cutaneous melanoma (SKCM) is the most frequently encountered tumor of the skin. Immunotherapy has opened a new horizon in melanoma treatment. We aimed to construct a CD8⁺ T cell-associated immune gene prognostic model (CDIGPM) for SKCM and unravel the immunologic features and the benefits of immunotherapy in CDIGPM-defined SKCM groups.

Method

Single-cell SKCM transcriptomes were utilized in conjunction with immune genes for the screening of CD8⁺ T cell-associated immune genes (CDIGs) for succeeding assessment. Thereafter, through protein-protein interaction (PPI) networks analysis, univariate COX analysis, and multivariate Cox analysis, six genes (MX1, RSAD2, IRF2, GBP2, IFITM1, and OAS2) were identified to construct a CDIGPM. We detected cell proliferation of SKCM cells transfected with IRF2 siRNA. Then, we analyzed the immunologic features and the benefits of immunotherapy in CDIGPM-defined groups.

Results

The overall survival (OS) was much better in low-CDIGPM group versus high CDIGPM group in TCGA dataset and GSE65904 dataset. On the whole, the results unfolded that a low CDIGPM showed relevance to immune response-correlated pathways, high expressions of CTLA4 and PD-L1, a high infiltration rate of CD8⁺ T cells, and more benefits from immunotherapy.

Conclusion

CDIGPM is an good model to predict the prognosis, the potential immune escape from immunotherapy for SKCM, and define immunologic and molecular features.

Biomarkers of Response and Resistance to Immunotherapy in Microsatellite Stable Colorectal Cancer: Toward a New Personalized Medicine

Immune Checkpoint Inhibitors (ICIs) are well recognized as a major immune treatment modality for multiple types of solid cancers. However, for colorectal cancer (CRC), ICIs are only approved for the treatment of Mismatch-Repair-Deficient and Microsatellite Instability-High (dMMR/MSI-H) tumors. For the vast majority of CRC, that are not dMMR/MSI-H, ICIs alone provide limited to no clinical benefit. This discrepancy of response between CRC and other solid cancers suggests that CRC may be inherently resistant to ICIs alone. In translational research, efforts are underway to thoroughly characterize the immune microenvironment of CRC to better understand the mechanisms behind this resistance and to find new biomarkers of response. In the clinic, trials are being set up to study biomarkers along with treatments targeting newly discovered immune checkpoint molecules or treatments combining ICIs with other existing therapies to improve response in MSS CRC. In this review, we will focus on the characteristics of response and resistance to ICIs in CRC, and discuss promising biomarkers studied in recent clinical trials combining ICIs with other therapies.

The Establishment and Experimental Verification of an lncRNA-Derived CD8+ T Cell Infiltration ceRNA Network in Colorectal Cancer

BACKGROUND

Long noncoding RNAs (LncRNA) lead a vital role in colorectal cancer (CRC) development. The infiltrating CD8+ T cell is the main target of immunotherapy. Our study aimed to figure out the potential mechanism of lncRNAs regulating the function of CD8+ T cells in CRC.

METHODS

We collected bulk RNA-seq, miRNA-seq, and single-cell RNA-seq (scRNA-seq) data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. The cibersort algorithm and correlation analysis were used to estimate the abundance of CD8+ T cells and screened out the most relevant lncRNAs. We used scRNA-seq data to identify the main cell lncRNA expressed. Furthermore, one competing endogenous RNA (ceRNA) network focusing on the potential mechanism of lncRNA-derived CD8+ T cell infiltration was constructed. We established a co-culture system to assess the immunosuppressive function of the lncRNA. And we evaluated the effects of the lncRNA on CD8+ T cell cytotoxicity by flow cytometry, qPCR, and clone formation assay.

RESULTS

Three CD8+ T cell infiltration-related lncRNAs were identified, and LINC00657 was expressed mainly in tumor cells, negatively associated with CD8+ T cell infiltration. Hsa-miRNA-1224-3p and hsa-miRNA-338-5p and SCD, ETS2, UBE2H, and YY1 were identified to construct the ceRNA network. Immunosuppression-related tumor marker CD155 was proved to be positively correlated with LINC00657 and mRNAs in the ceRNA network. In addition, we proved that LINC00657 could impair the cytotoxicity of CD8+ T cells, and its expression was positively associated with CD155 in vitro.

CONCLUSIONS

We successfully constructed an lncRNA-derived CD8+ T cell infiltration ceRNA network in CRC. LINC00657 may play a leading role in the CRC immune escape and could be a novel immunotherapy target.

Visual Analysis of Colorectal Cancer Immunotherapy: A Bibliometric Analysis From 2012 to 2021

An increasing number of studies have shown that immunotherapy serves a significant role in treating colorectal cancer (CRC) and has become a hotspot. However, few studies used the bibliometric method to analyze this field comprehensively. This study collected 1,899 records of CRC immunotherapy from 2012 to October 31, 2021, and used CiteSpace to analyze regions, institutions, journals, authors, and keywords to predict the latest trends in CRC immunotherapy research. The United States and China, contributing more than 60% of publications, were the main drivers in this field. Sun Yat-sen University was the most active institution, while the National Cancer Institute had the highest frequency of citations. Most publications were published in the Journal for Immunotherapy of Cancer. Adam E Snook was the most prolific writer, while Dung T. Le was the most commonly co-cited author. “T cell”, “MMI” and “PD-1blocked” were the most widely studied aspects of CRC immunotherapy. “Immune checkpoint inhibitor”, “combination therapy”, “drug therapy” and “liver metastases” were current research hotspots. “Tumor microenvironment”, “neutrophils”, “tumor-associated macrophages”, and “suppressor cell” have emerged as research hotspots in recent years. “Gut microbiota”, “nanoparticle” and “tumor mutational burden” as recently emerged frontiers of research that should be closely monitored.

Biochanin A Suppresses Tumor Progression and PD-L1 Expression via Inhibiting ZEB1 Expression in Colorectal Cancer

Objective. To investigate the regulatory effect of ZEB1 on PD-L1 expression and the pharmacodynamic effects of Biochanin A on the malignant biological behaviors of colorectal cancer (CRC). Methods. The correlation between epithelial-mesenchymal transition (EMT) score and features of the tumor microenvironment (TME) was investigated using the Cancer Genome Atlas (TCGA) dataset. The correlation between ZEB1 and PD-L1 expression was validated using immunohistochemistry (IHC) staining, and the regulatory effect of ZEB1 on PD-L1 expression was explored by in vitro assays. Moreover, the pharmacodynamic effects of Biochanin A on ZEB1 and PD-L1 expression, as well as malignant biological behaviors of CRC cells, were evaluated by in vitro and in vivo assays. Results. EMT score was positively correlated with a majority of immunostimulators, immune checkpoints, activities of antitumor immunity cycles, and infiltration levels of most immune cells in the TCGA dataset. In addition, ZEB1 was correlated with and positively regulated PD-L1 expression in CRC. Besides, Biochanin A, an inhibitor for the ZEB1/PD-L1 axis, notably inhibited ZEB1-mediated aggressiveness and PD-L1 expression of CRC cells. Moreover, Biochanin A also exerted a tumor-inhibitory role in vivo in the CRC mouse model. Conclusion. Overall, we found that ZEB1 is a main regulator of PD-L1 expression in CRC. In addition, we also identified Biochanin A as a novel inhibitor for the ZEB1/PD-L1 axis, which could inhibit tumor progression and immune escape.

Neutrophils Extracellular Traps Inhibition Improves PD-1 Blockade Immunotherapy in Colorectal Cancer

Immune checkpoint inhibitors can improve the prognosis of patients with advanced malignancy; however, only a small subset of advanced colorectal cancer patients in microsatellite-instability-high or mismatch-repair-deficient colorectal cancer can benefit from immunotherapy. Unfortunately, the mechanism behind this ineffectiveness is unclear. The tumor microenvironment plays a critical role in cancer immunity, and may contribute to the inhibition of immune checkpoint inhibitors and other novel immunotherapies in patients with advanced cancer. Herein, we demonstrate that the DNase I enzyme plays a pivotal role in the degradation of NETs, significantly dampening the resistance to anti-PD-1 blockade in a mouse colorectal cancer model by attenuating tumor growth. Remarkably, DNase I decreases tumor-associated neutrophils and the formation of MC38 tumor cell-induced neutrophil extracellular trap formation in vivo. Mechanistically, the inhibition of neutrophil extracellular traps with DNase I results in the reversal of anti-PD-1 blockade resistance through increasing CD8+ T cell infiltration and cytotoxicity. These findings signify a novel approach to targeting the tumor microenvironment using DNase I alone or in combination with immune checkpoint inhibitors.

The Adaptive Immune Landscape of the Colorectal Adenoma-Carcinoma Sequence

BACKGROUND

The tumor immune microenvironment exerts a pivotal influence in tumor initiation and progression. The aim of this study was to analyze the immune context of sporadic and familial adenomatous polyposis (FAP) lesions along the colorectal adenoma-carcinoma sequence (ACS).

METHODS

We analyzed immune cell counts (CD3+, CD4+, CD8+, Foxp3+, and CD57+), tumor mutation burden (TMB), MHC-I expression and PD-L1 expression of 59 FAP and 74 sporadic colorectal lesions, encompassing adenomas with low-grade dysplasia (LGD) (30 FAP; 30 sporadic), adenomas with high-grade dysplasia (22 FAP; 30 sporadic), and invasive adenocarcinomas (7 FAP; 14 sporadic).

RESULTS

The sporadic colorectal ACS was characterized by (1) a stepwise decrease in immune cell counts, (2) an increase in TMB and MHC-I expression, and (3) a lower PD-L1 expression. In FAP lesions, we observed the same patterns, except for an increase in TMB along the ACS. FAP LGD lesions harbored lower Foxp3+ T cell counts than sporadic LGD lesions. A decrease in PD-L1 expression occurred earlier in FAP lesions compared to sporadic ones.

CONCLUSIONS

The colorectal ACS is characterized by a progressive loss of adaptive immune infiltrate and by the establishment of a progressively immune cold microenvironment. These changes do not appear to be related with the loss of immunogenicity of tumor cells, or to the onset of an immunosuppressive tumor microenvironment.

Role of Ezrin/Radixin/Moesin in the Surface Localization of Programmed Cell Death Ligand-1 in Human Colon Adenocarcinoma LS180 Cells

Programmed cell death ligand-1 (PD-L1), an immune checkpoint protein highly expressed on the cell surface in various cancer cell types, binds to programmed cell death-1 (PD-1), leading to T-cell dysfunction and tumor survival. Despite clinical successes of PD-1/PD-L1 blockade therapies, patients with colorectal cancer (CRC) receive little benefit because most cases respond poorly. Because high PD-L1 expression is associated with immune evasion and poor prognosis in CRC patients, identifying potential modulators for the plasma membrane localization of PD-L1 may represent a novel therapeutic strategy for enhancing the efficacy of PD-1/PD-L1 blockade therapies. Here, we investigated whether PD-L1 expression in human colorectal adenocarcinoma cells (LS180) is affected by ezrin/radixin/moesin (ERM), functioning as scaffold proteins that crosslink plasma membrane proteins with the actin cytoskeleton. We observed colocalization of PD-L1 with all three ERM proteins in the plasma membrane and detected interactions involving PD-L1, the three ERM proteins, and the actin cytoskeleton. Furthermore, gene silencing of ezrin and radixin, but not of moesin, substantially decreased the expression of PD-L1 on the cell surface without affecting its mRNA level. Thus, in LS180 cells, ezrin and radixin may function as scaffold proteins mediating the plasma membrane localization of PD-L1, possibly by post-translational modification.