Integrative Analyses of Colorectal Cancer Show Immunoscore Is a Stronger Predictor of Patient Survival Than Microsatellite Instability

A Tc1- and Th1-T-lymphocyte-rich tumor microenvironment is a hallmark of MSI colorectal cancer

Microsatellite instability is a strong predictor of response to immune checkpoint therapy and patient outcome in colorectal cancer. Although enrichment of distinct T-cell subpopulations has been determined to impact the response to immune checkpoint therapy and patient outcome, little is known about the underlying changes in the composition of the immune tumor microenvironment. To assess the density, composition, degree of functional marker expression, and spatial interplay of T-cell subpopulations, 79 microsatellite instable (MSI) and 1,045 microsatellite stable (MSS) colorectal cancers were analyzed. A tissue microarray and large sections were stained with 19 antibodies directed against T cells, antigen-presenting cells, functional markers, and structural proteins using our BLEACH&STAIN multiplex-fluorescence immunohistochemistry approach. A deep learning-based framework comprising >20 different convolutional neuronal networks was developed for image analysis. The composition of Type 1 (T-bet+), Type 2 (GATA3+), Type 17 (RORγT+), NKT-like (CD56+), regulatory (FOXP3+), follicular (BCL6+), and cytotoxic (CD3+CD8+) or helper (CD3+CD4+) T cells showed marked differences between MSI and MSS patients. For instance, the fraction of Tc1 and Th1 was significantly higher (p < 0.001 each), while the fraction of Tregs, Th2, and Th17 T cells was significantly lower (p < 0.05) in MSI compared to MSS patients. The degree of TIM3, CTLA-4, and PD-1 expression on most T-cell subpopulations was significantly higher in MSI compared to MSS patients (p < 0.05 each). Spatial analysis revealed increased interactions between Th1, Tc1, and dendritic cells in MSI patients, while in MSS patients the strongest interactions were found between Tregs, Th17, Th2, and dendritic cells. The additional analysis of 12 large sections revealed a divergent immune composition at the invasive margin. In summary, this study identified a higher fraction of Tc1 and Th1 T cells accompanied by a paucity of regulatory T-cell, Th17, and Th2 T-cell subpopulations, along with a distinct interaction profile, as a hallmark of MSI compared to MSS colorectal cancers. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Systemic inflammation in response to radiation drives the genesis of an immunosuppressed tumor microenvironment

The composition of the tumor immune microenvironment has become a major determinant of response to therapy, particularly immunotherapy. Clinically, a tumor microenvironment lacking lymphocytes, so-called "cold" tumors, are considered poor candidates for immune checkpoint inhibition. In this review, we describe the diversity of the tumor immune microenvironment in breast cancer and how radiation exposure alters carcinogenesis. We review the development and use of a radiation-genetic mammary chimera model to clarify the mechanism by which radiation acts. Using the chimera model, we demonstrate that systemic inflammation elicited by a low dose of radiation is key to the construction of an immunosuppressive tumor microenvironment, resulting in aggressive, rapidly growing tumors lacking lymphocytes. Our experimental studies inform the non-mutagenic mechanisms by which radiation affects cancer and provide insight into the genesis of cold tumors.

Computed tomography-based deep learning radiomics model for preoperative prediction of tumor immune microenvironment in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death globally, with the tumor immune microenvironment (TIME) influencing prognosis and immunotherapy response. Current TIME evaluation relies on invasive biopsies, limiting its clinical application. This study hypothesized that computed tomography (CT)-based deep learning (DL) radiomics models can non-invasively predict key TIME biomarkers: Tumor-stroma ratio (TSR), tumor-infiltrating lymphocytes (TILs), and immune score (IS).

AIM

To develop a non-invasive DL approach using preoperative CT radiomics to evaluate TIME components in CRC patients.

METHODS

In this retrospective study, preoperative CT images of 315 pathologically confirmed CRC patients (220 in training cohort and 95 in validation cohort) were analyzed. Manually delineated regions of interest were used to extract DL features. Predictive models (DenseNet-121/169) for TSR, TILs, IS, and TIME classification were constructed. Performance was evaluated via receiver operating characteristic curves, calibration curves, and decision curve analysis (DCA).

RESULTS

The DL-DenseNet-169 model achieved area under the curve (AUC) values of 0.892 [95% confidence interval (CI): 0.828-0.957] for TSR and 0.772 (95%CI: 0.674-0.870) for TIME score. The DenseNet-121 model yielded AUC values of 0.851 (95%CI: 0.768-0.933) for TILs and 0.852 (95%CI: 0.775-0.928) for IS. Calibration curves demonstrated strong prediction-observation agreement, and DCA confirmed clinical utility across threshold probabilities (P < 0.05 for all models).

CONCLUSION

CT-based DL radiomics provides a reliable non-invasive method for preoperative TIME evaluation, enabling personalized immunotherapy strategies in CRC management.

Mechanisms of Response and Resistance to PSMA×CD3 Bispecifics in CD34+ Humanized Mice

Prostate cancer is considered immunologically "cold," with low mutational burden, tumor-infiltrating immune cells, and PD-L1 levels, culminating in poor response to immune checkpoint therapies. CD3 bispecific redirection antibodies can elicit T cell-mediated cytotoxicity and hold promise for immune cell recruitment into prostate tumors. CD3 redirection antibodies in solid tumors are still in the early phases of clinical development, and it is not yet understood whether these potential therapies will achieve the high response rates observed in hematologic malignancies or result in durable T-cell responses. In this study, we demonstrated that treatment with a prostate-specific membrane antigen (PSMA)-targeted CD3 redirector resulted in efficacy against LnCaP.AR human prostate xenografts in CD34+ cord blood-humanized mice. Efficacy correlated with T-cell infiltration into tumors with an activated phenotype and also increased PD-L1 expression. Engineered overexpression of PD-L1 in LNCaP.AR tumors resulted in resistance to PSMA×CD3 bispecific antibody treatment, whereas sensitivity was restored in combination with anti-PD-1 antibody pembrolizumab. PSMA×CD3 and anti-PD-1 combination treatment resulted in complete tumor responses in approximately 20% of mice and elicited immune responses that delayed growth of rechallenged tumors. In a second prostate model, patient-derived LuCaP 86.2 xenografts, PSMA×CD3 monotherapy treatment resulted in complete responses in 25% of mice. When PSMA×CD3-treated responder mice were rechallenged with LuCaP 86.2 tumors, partial control of tumor regrowth was associated with the expansion of effector memory T cells. These studies show that PSMA×CD3 treatment elicits antitumor memory T-cell responses and that combination with PD-1 blockade can enhance these effects in tumors with immune-suppressive tumor microenvironments.

Progressive accumulation of circulating CD27-CD28- effector/memory CD8+ T cells in patients with lung cancer blunts responses to immune checkpoint inhibitor therapy

Suppression of tumor-reactive CD8+ T cells is common within the tumor microenvironment. However, little is known about how tumors systemically affect the overall CD8+ T cell compartment. Here we demonstrate that peripheral blood CD8+ T cells from patients with lung cancer showed altered compositions particularly within CD45RA-CCR7- effector memory subpopulation. Specifically, patients with lung cancer exhibited increased frequency of more differentiated effector memory cells, which are less susceptible to T cell-receptor-induced proliferation. Further analysis using single-cell RNA sequencing revealed that these alterations were correlated with reduced quiescence and increased spontaneous activation at a systemic level, indicative of homeostatic dysregulation of the entire CD8+ T cell population. This phenomenon was found to be correlated with a poor clinical response to immune checkpoint inhibitor therapy across four independent cohorts, consisting of a total of 224 patients with lung cancer. These findings suggest that lung cancers continue to counteract potentially tumor-reactive CD8+ T cells by inducing homeostatic dysregulation of the entire CD8+ T cell compartment systematically.

Navigating established and emerging biomarkers for immune checkpoint inhibitor therapy

Immune checkpoint inhibitors (ICIs) have improved outcomes of patients with many different cancers. These antibodies target molecules such as programmed cell death 1 (PD-1) or cytotoxic T lymphocyte associated protein 4 (CTLA-4) which normally function to limit immune activity. Treatment with ICIs reactivates T cells to destroy tumor cells in a highly specific manner, which in some patients, results in dramatic remissions and durable disease control. Over the last decade, much effort has been directed at characterizing factors that drive efficacy and resistance to ICI therapy. Food and Drug Administration (FDA)-approved biomarkers for ICI therapy have facilitated more judicious treatment of cancer patients and transformed the field of precision oncology. Yet, adaptive immunity against cancers is complex, and newer data have revealed the potential utility of other biomarkers. In this review, we discuss the utility of currently approved biomarkers and highlight how emerging biomarkers can further improve the identification of patients who benefit from ICIs.

The prognostic impact of tumor mutations and tumor-infiltrating lymphocytes in patients with localized pMMR colorectal cancer - A systematic review and meta-analysis

BACKGROUND

Tumor mutations and the composition of the tumor microenvironment have prognostic and therapeutic significance in colorectal cancer (CRC). However, immunotherapy remains a challenge for patients with proficient mismatch repair (pMMR) CRC. In this paper, the association between tumor-infiltrating lymphocytes (TILs) and tumor mutations on survival outcomes in patients with localized pMMR CRC was examined.

METHODS

A systematic review of the literature and a meta-analysis were conducted in accordance with the PRISMA guidelines. The literature search was conducted in PubMed, Embase, Cochrane Library, and Web of Science. The outcomes of interest were overall survival, disease-free survival, and cancer-specific survival. The risk of bias was assessed through the Newcastle-Ottawa Scale and the quality of the cumulative evidence was evaluated through the modified GRADE approach.

FINDINGS

In total, 8498 articles were screened for eligibility and 44 articles were included in the meta-analysis with 33,704 patients in total. Patients with high infiltration of any TILs showed significantly improved overall survival (HR = 0.57, 95 % CI: 0.49-0.67, I2: 0 %), especially for the subgroup of CD3 + (HR = 0.52, 95 % CI: 0.38-0.71, I2: 0 %) and CD8 + (HR = 0.60, 95 % CI: 0.37-0.99, I2: 10 %) TILs. Patients with BRAF mutation (HR = 2.68, 95 % CI: 1.47-4.89, I2: 83 %) and KRAS mutation (HR = 1.25, 95 % CI: 1.18-1.33, I2: 0 %) showed decreased overall survival.

INTERPRETATION

High infiltration of TILs, especially CD3 + and CD8 + , was associated with significantly improved survival, while BRAF and KRAS mutations were correlated with worse survival outcomes for patients with non-metastatic pMMR CRC.

Evaluation of immune-checkpoint molecules in dMMR/pMMR colorectal cancer by multiplex immunohistochemistry

PURPOSE

Colorectal cancer is the most common malignancy worldwide. A number of pathological and molecular genetic criteria are currently used as predictors of the disease. They include assessment of MMR deficiency or MSI/MSS status, which among others, determine the immunogenicity of the tumor. In this regard, the evaluation of PD-L1, CTLA-4, and LAG-3 immune checkpoint molecules in different tumor compartments according to MMR status deserves special attention.

METHODS

Multiplex immunohistochemistry was used to evaluate the expression of immune checkpoint molecules in the tumor core and at the invasive margin.

RESULTS

Data analysis showed the predominance of PD-L1 (p = 0.011), CTLA-4 (p = 0.004), and LAG-3 (p = 0.013) expression at the invasive margin of dMMR carcinomas compared to pMMR samples. Quantitative analysis of TILs population in the tumor core and at the invasive margin allowed establishment of the predominance of CD3+ and CD8+ lymphocytes at the invasive margin of dMMR carcinomas. Study of the CD163+ macrophages population in the same tumor compartments revealed the predominance of the studied TAMs in the core and at the invasive margin of dMMR carcinomas and the predominance of CD163+ macrophages with PD-L1-phenotype in the tumor stroma.

CONCLUSION

This study revealed a significant predominance of PD-L1, CTLA-4, LAG-3, and CD 3+ ,CD8+ lymphocytes in dMMR colorectal carcinomas. Further research on the immune landscape in different tumor compartments will likely have high prognostic value for CRC patients, as it might expand the criteria for prescribing immunotherapy.

Pathomics Image Analysis of Tumor Infiltrating Lymphocytes (TILs) in Colon Cancer

We developed a deep learning Pathomics image analysis workflow to generate spatial Tumor-TIL maps to visualize and quantify the abundance and spatial distribution of tumor infiltrating lymphocytes (TILs) in colon cancer. Colon cancer and lymphocyte detection in hematoxylin and eosin (H&E) stained whole slide images (WSIs) has revealed complex immuno-oncologic interactions that form TIL-rich and TIL-poor tumor habitats, which are unique in each patient sample. We compute Tumor%, total lymphocyte%, and TILs% as the proportion of the colon cancer microenvironment occupied by intratumoral lymphocytes for each WSI. Kaplan-Meier survival analyses and multivariate Cox regression were utilized to evaluate the prognostic significance of TILs% as a Pathomics biomarker. High TILs% was associated with improved overall survival (OS) and progression-free interval (PFI) in localized and metastatic colon cancer and other clinicopathologic variables, supporting the routine use of Pathomics Tumor-TIL mapping in biomedical research, clinical trials, laboratory medicine, and precision oncology.

Characterizing macrophage diversity in colorectal malignancies through single-cell genomics

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract, with increasing incidence and mortality rates, posing a significant burden on human health. Its progression relies on various mechanisms, among which the tumor microenvironment and tumor-associated macrophages (TAMs) have garnered increasing attention. Macrophage infiltration in various solid tumors is associated with poor prognosis and is linked to chemotherapy resistance in many cancers. These significant biological behaviors depend on the heterogeneity of macrophages. Tumor-promoting TAMs comprise subpopulations characterized by distinct markers and unique transcriptional profiles, rendering them potential targets for anticancer therapies through either depletion or reprogramming from a pro-tumoral to an anti-tumoral state. Single-cell RNA sequencing technology has significantly enhanced our research resolution, breaking the traditional simplistic definitions of macrophage subtypes and deepening our understanding of the diversity within TAMs. However, a unified elucidation of the nomenclature and molecular characteristics associated with this diversity remains lacking. In this review, we assess the application of conventional macrophage polarization subtypes in colorectal malignancies and explore several unique subtypes defined from a single-cell omics perspective in recent years, categorizing them based on their potential functions.

Deep-learning enabled combined measurement of tumour cell density and tumour infiltrating lymphocyte density as a prognostic biomarker in colorectal cancer

BACKGROUND

Within the colorectal cancer (CRC) tumour microenvironment, tumour infiltrating lymphocytes (TILs) and tumour cell density (TCD) are recognised prognostic markers. Measurement of TILs and TCD using deep-learning (DL) on haematoxylin and eosin (HE) whole slide images (WSIs) could aid management.

METHODS

HE WSIs from the primary tumours of 127 CRC patients were included. DL was used to quantify TILs across different regions of the tumour and TCD at the luminal surface. The relationship between TILs, TCD, and cancer-specific survival was analysed.

RESULTS

Median TIL density was higher at the invasive margin than the luminal surface (963 vs 795 TILs/mm2, P = 0.010). TILs and TCD were independently prognostic in multivariate analyses (HR 4.28, 95% CI 1.87-11.71, P = 0.004; HR 2.72, 95% CI 1.19-6.17, P = 0.017, respectively). Patients with both low TCD and low TILs had the poorest survival (HR 10.0, 95% CI 2.51-39.78, P = 0.001), when compared to those with a high TCD and TILs score.

CONCLUSIONS

DL derived TIL and TCD score were independently prognostic in CRC. Patients with low TILs and TCD are at the highest risk of cancer-specific death. DL quantification of TILs and TCD could be used in combination alongside other validated prognostic biomarkers in routine clinical practice.

Oronasal mucosal melanoma is defined by two transcriptional subtypes in humans and dogs with implications for diagnosis and therapy

Mucosal melanoma is a rare melanoma subtype associated with a poor prognosis and limited existing therapeutic interventions, in part due to a lack of actionable targets and translational animal models for preclinical trials. Comprehensive data on this tumour type are scarce, and existing data often overlooks the importance of the anatomical site of origin. We evaluated human and canine oronasal mucosal melanoma (OMM) to determine whether the common canine disease could inform the rare human equivalent. Using a human and canine primary OMM cohort of treatment-naive archival tissue, alongside clinicopathological data, we obtained transcriptomic, immunohistochemical, and microbiome data from both species. We defined the transcriptomic landscape in both species and linked our findings to immunohistochemical, microbiome, and clinical data. Human and dog OMM stratified into two distinctive transcriptional groups, which we defined using a species-independent 41-gene signature. These two subgroups are termed CTLA4-high and MET-high and indicate actionable targets for OMM patients. To guide clinical decision-making, we developed immunohistochemical diagnostic tools that distinguish between transcriptomic subgroups. We found that OMM had conserved transcriptomic subtypes and biological similarity between human and canine OMM, with significant implications for patient classification, treatment, and clinical trial design. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

SUSD2+ cancer-associated fibroblasts in gastric cancer mediate the effect of immunosuppression and predict overall survival and the effectiveness of neoadjuvant immunotherapy

BACKGROUND

The expression patterns and functions of Sushi Domain Containing 2 (SUSD2) differ among various malignancies. This research aims to investigate the expression of SUSD2 and the role of the SUSD2+ cancer-associated fibroblasts (CAFs) for immunotherapy in gastric cancer.

METHODS

The expression of SUSD2 and specific markers (CD4, CD8, PD-1, TIGIT, TIM-3 and CD163) was determined using immunohistochemistry and multiplex immunofluorescence (mIHC) on paraffin sections. Flow cytometry and western blot were used to assess the expression of SUSD2 in fibroblasts from fresh samples. Also, analysis of single-cell and bulk RNA sequencing was employed to confirm the presence and characterize the function of SUSD2+ CAFs. The predictive power of indicators for neoadjuvant immunotherapy was evaluated via ROC curve analysis. Animal experiment was employed to validate the immunosuppressive effect of SUSD2+ CAFs.

RESULTS

SUSD2 is mainly expressed on fibroblasts within the tumors and the high infiltration of SUSD2+ CAFs went together with a poor survival and a more advanced tumor stage. Significantly, the joint use of SUSD2+ CAFs and CD8+ T cells demonstrated a remarkable ability to predict the efficacy of neoadjuvant immunotherapy superior to PD-L1 combined positive score. High SUSD2+ CAFs was correlated with resistance to immunotherapy as well as low CD8+ T infiltration and high exhausted T cell infiltration.

CONCLUSIONS

We have identified a novel subset of CAFs that could predict the survival and response to neoadjuvant immunotherapy of patients. The SUSD2+ CAFs have the potential to serve as a predictive biomarker and a promising target for immunotherapy.

Cytotoxic Response of CD4+ T Cells Orchestrated by SLAMF4 in Rheumatoid Arthritis

OBJECTIVE

This study aimed to assess whether signaling lymphocytic activation molecule family receptors (SLAMFs) are involved in the shaping of the pathologic response of CD4+ T cells in rheumatoid arthritis (RA).

METHODS

Peripheral blood (PB) and synovial fluid (SF) mononuclear cells from patients with RA were freshly isolated. In RA, we used a multimodal approach to determine the involvement of numerous subpopulations of CD4+ T cells expressing SLAMFs. Experimentally, multiple flow cytometry panels, RNA sequencing, and stimulations were used. Analyses involved high-dimensional unsupervised clustering of flow cytometry data and pathway enrichment analyses of transcriptomic data.

RESULTS

In PB of patients with RA with active disease, SLAMF4+ effector memory CD4+ T cells (Tem) represented the only overrepresented subpopulation of CD4+ T cells expressing SLAMFs. This positive correlation between RA activity and SLAMF4+ Tem was restricted to those coexpressing the intracellular molecule SLAM-associated protein (SAP) and the tissue-homing receptor CCR5. Gene Set Enrichment Analysis of RNA sequencing data reveals that SLAMF4+ CCR5+ Tem display a cytotoxicity-related gene signature. Moreover, based on the differential expression of cytotoxicity markers (GPR56, CX3CR1, granzyme-B, perforin, and granulysin), unsupervised clustering of flow cytometry data identified distinct subpopulations of PB cytotoxic Tem. Among them, only SLAMF4high SAP+ CCR5+ Tem (Cytotox-F4high Tem) were correlated with RA activity. Remarkably, Cytotox-F4high Tem emerged as the only cytotoxic population of CD4+ T cells (CD4+ CTLs) present in SF of patients with active disease.

CONCLUSION

This study emphasizes that Cytotox-F4high Tem represent a significant CD4+ CTL subpopulation involved in RA, suggesting that their inhibition represent a promising therapeutic interest.

Effect of RAS mutations and related immune characteristics on the prognosis of patients with MSI-H/dMMR colorectal cancer

PURPOSE

Microsatellite high instability/deficient mismatch repair (MSI-H/dMMR) colorectal cancer (CRC) has an active tumor microenvironment, rendering it more sensitive to immune checkpoint inhibitors. Given that studies involving patients with MSI-H colorectal cancer with RAS mutations are scarce, we explored the effect of RAS mutations on the TME in patients with MSI-H/dMMR cancer and identified potential prognostic factors.

METHODS

Seventy-five patients diagnosed with MSI-H/dMMR colorectal cancer were retrospectively enrolled and divided into RAS-mutant and -wild-type groups. The expression levels of CD11c+ dendritic cells, CD4+ T cells, CD8+ T cells, and regulatory T cell (Treg) markers were detected, and prognostic factors were analyzed.

RESULTS

RAS-mutant MSI-H colorectal patients were more likely to have: (1) higher platelet values; (2) shorter disease-free survival (DFS); (3) lower infiltrated numbers of CD11c+ dendritic cells, CD4+ T lymphocytes, and CD8+ T lymphocytes, and higher infiltrated numbers of Foxp3+ Treg cells. In MSI-H/dMMR CRC patients: (1) the high CD11c + , CD4 +,  and CD8 +  cells infiltration group had longer DFS than the low-infiltration group, and Foxp3 + cells infiltration was not significantly correlated with DFS; (2) the RAS mutation status, number of CD11c+ cells infiltrated, and carbohydrate antigen 19-9 (CA19-9) level were the potential prognostic factors.

CONCLUSION

RAS mutations in patients with MSI-H/dMMR CRC may reduce the infiltration of CD11c+ dendritic cells, CD4+ T cells, and CD8+ T cells, and increase the infiltration of Foxp3+ Treg cells to affect the tumor microenvironment of patients. RAS gene status, CD11c + cells infiltration, and CA19-9 level were potential prognostic factors for MSI-H/dMMR CRC.

Complete blood counts as potential risk factors of early dissemination to liver and lungs in resected colorectal cancer: a retrospective cohort study

PURPOSE

Liver and lung metastases demonstrate distinct biological, particularly immunological, characteristics. We investigated whether preoperative complete blood count (CBC) parameters, which may reflect the immune system condition, predict early dissemination to the liver and lungs in colorectal cancer (CRC).

METHODS

In this retrospective single-centre study, we included 268 resected CRC cases with complete 2-year follow-up and analysed preoperative CBC for association with early liver or lung metastasis development. Next, selected CBC and clinicopathological parameters were analysed with uni- and multivariable Cox regression. Independent factors affecting liver or lung metastasis-free survival were incorporated into composite scores, which were further evaluated with receiver operating characteristic (ROC) curves and dichotomised using a modified, specificity-focused, Youden approach to identify particularly high-risk patients.

RESULTS

Compared to metastasis-free patients, early liver metastases were related to decreases in red blood cells, haematocrit, lymphocytes and elevated monocyte-to-lymphocyte ratio, while lung metastases to lower eosinophil counts. A composite score of independent factors (erythrocytopenia, lower lymphocyte count and pN) yielded HR of 8.01 (95% CI 3.45-18.57, p < 0.001) for liver-specific metastasis-free survival (MFS). For lung-specific MFS, the combination of eosinopenia, pN and primary tumour location showed HR of 13.69 (95% CI 4.34-43.20, p < 0.001).

CONCLUSION

Early CRC metastases to the liver and lungs are associated with partially divergent clinicopathological and peripheral blood features. We propose simple, clinically implementable scores, based on routinely assessed parameters, to identify patients with an increased risk of early dissemination to the liver or lungs. After validation in independent cohorts, these scores may provide easily available prognostic information.

The characteristics of the tumor immune microenvironment in colorectal cancer with different MSI status and current therapeutic strategies

Colorectal cancer (CRC) remains a significant cause of cancer-related mortality worldwide. Despite advancements in surgery, chemotherapy, and radiotherapy, the effectiveness of these conventional treatments is limited, particularly in advanced cases. Therefore, transition to novel treatment is urgently needed. Immunotherapy, especially immune checkpoint inhibitors (ICIs), has shown promise in improving outcomes for CRC patients. Notably, patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) tumors often benefit from ICIs, while the majority of CRC cases, which exhibit proficient mismatch repair (pMMR) or microsatellite-stable (MSS) status, generally show resistance to this approach. It is assumed that the MSI phenotype cause some changes in the tumor microenvironment (TME), thus triggering antitumor immunity and leading to response to immunotherapy. Understanding these differences in the TME relative to MSI status is essential for developing more effective therapeutic strategies. This review provides an overview of the TME components in CRC and explores current approaches aimed at enhancing ICI efficacy in MSS CRC.

Tumor-Infiltrating Immune Cells in Colorectal Cancer

Colorectal cancer encompasses a heterogeneous group of malignancies that differ in pathophysiological mechanisms, immune response and infiltration, therapeutic response, and clinical prognosis. Numerous studies have highlighted the clinical relevance of tumor-infiltrating immune cells among different types of colorectal tumors yet vary in cell type definitions and cell identification strategies. The distinction of immune signatures is particularly challenging when several immune subtypes are involved but crucial to identify novel intercellular mechanisms within the tumor microenvironment. In this review, we compile human and non-human studies on tumor-infiltrating immune cells and provide an overview of immune subtypes, their pathophysiological functions, and their prognostic role in colorectal cancer. We discuss how differentiating immune signatures can guide the development of immunotherapeutic targets and personalized treatment regimens. We analyzed comprehensive human protein biomarker profiles across the entire immune spectrum to improve interpretability and application of tumor studies and to ultimately enhance immunotherapy and advance precision medicine for colorectal cancer patients.

Beta-2-microglobulin positive tumor cells and CD8 positive lymphocytes are associated with outcome in post-neoadjuvant colorectal cancer resections

Locally advanced colorectal cancers are treated with neoadjuvant therapy (NAT), which has been shown to alter the characteristics of the tumor including size, lymph node yield, and histologic grade. We seek to interrogate the effect of NAT on the immune microenvironment. We compared 190 patients with colorectal adenocarcinoma treated with NAT with those without NAT (n = 926). We evaluated clinicopathologic and molecular factors and performed immunohistochemistry and quantification on tissue microarrays for HLA class I/II proteins, beta-2-microglobulin (B2M), CD8, CD163, LAG3, PD-L1, and FoxP3. Patients in the NAT group were younger (60.9 vs 67.9, p < 0.001) and more often male (59.5 vs. 47.9, p = 0.004) than those in the non-NAT group. Tumors in the NAT group were smaller (3.5 vs 4.7 cm, p < 0.001), less often high grade (6.5% vs. 16.2%, p = 0.001), more frequently in the rectum (68.9% vs. 6.6%, p < 0.001) and associated with lower lymph node yields (p = 0.002); however, the incidence of extramural venous invasion, perineural invasion, and AJCC stage 3-4 disease were not different. Immune cells positive for CD8 (p = 0.011) were significantly lower in the NAT group. A high number of CD8+ cells and higher expression of B2M in tumor cells showed a significant survival benefit in both NAT and non-NAT group. NAT is associated with an immune-low tumor environment. CD8+ cells and tumor B2M expression may help identify a subset of immune high-tumors following NAT. This identification could aid in determining patients who may benefit from conservative management of colorectal carcinomas.

Multiomics reveals tumor microenvironment remodeling in locally advanced gastric and gastroesophageal junction cancer following neoadjuvant immunotherapy and chemotherapy

BACKGROUND

Perioperative chemotherapy is the standard of care for patients with locally advanced gastric and gastroesophageal junction cancer. Recent evidence demonstrated the addition of programmed cell death protein 1 (PD-1) inhibitors enhanced therapeutic efficacy. However, the mechanisms of response and resistance remain largely undefined. A detailed multiomic investigation is essential to elucidate these mechanisms.

METHODS

We performed whole-exome sequencing, whole-transcriptome sequencing, multiplex immunofluorescence and single-cell RNA sequencing on matched pretreatment and post-treatment samples from 30 patients enrolled in an investigator-initiated Phase 2 clinical trial (NCT04908566). All patients received neoadjuvant PD-1 inhibitors in combination with chemotherapy. A major pathologic response (MPR) was defined as the presence of no more than 10% residual viable tumor cells following treatment.

RESULTS

Before treatment, the positive ratio of CD3+T cells in both the tumor parenchyma and stroma was significantly higher in the non-MPR group compared with the MPR group (p=0.042 and p=0.013, respectively). Least absolute shrinkage and selection operator regression was employed for feature gene selection and 13 genes were ultimately used to construct a predictive model for identifying MPR after surgery. The model exhibited a perfect area under curve (AUC) of 1.000 (95% CI: 1.000 to 1.000, p<0.001). Post-treatment analysis revealed a significant increase in CD3+T cells, CD8+T cells and NK cells in the tumor stroma of MPR patients. In the tumor parenchyma, aside from a marked increase in CD8+T cells and NK cells, a notable reduction in macrophage was also observed (all p<0.05). Importantly, forkheadbox protein 3 (FOXP3), the principal marker for regulatory T cells (Treg) cells, showed a significant decrease during treatment in MPR patients. FOXP3 expression in the non-MPR group was significantly higher than in the MPR group (p=0.0056) after treatment. Furthermore, single-cell RNA sequencing analysis confirmed that nearly all Treg cells were derived from the non-MPR group.

CONCLUSIONS

Our study highlights the critical role of dynamic changes within the tumor immune microenvironment in predicting the efficacy of neoadjuvant combined immunochemotherapy. We examined the disparities between MPR/non-MPR groups, shedding light on potential mechanisms of immune response and suppression. In addition to bolstering cytotoxic immune responses, specifically targeting Treg cells may be crucial for enhancing treatment outcomes.

Radioresistance-related gene signatures identified by transcriptomics characterize the prognosis and immune landscape of pancreatic cancer patients

BACKGROUND

Radiotherapy (RT) is an important means of local treatment of solid tumors, and radioresistance is the main reason for RT failure for tumors, especially pancreatic cancer (PC). It is urgent to distinguish key genes and mechanisms of radioresistance in PC.

METHODS

We acquired the data from The Cancer Genome Atlas (TCGA), obtained the gene modules associated with radioresistance by weighted gene coexpression network analysis (WGCNA), and identified differentially expressed genes (DEGs) between normal and tumor samples. Radioresistance-related genes (RRRGs) were determined with the intersection of WGCNA and DEGs. The hub RRRGs associated with prognosis were distinguished by the least absolute shrinkage and selection operator (LASSO) regression. We established a risk score model using multivariate Cox regression. Immune cell infiltration and drug sensitivity were evaluated through the CIBERSORT algorithm and the "OncoPredict" software package, respectively. The association of the key gene RIC3 and PC clinical features was verified in public databases, and its biological behaviors were explored in vitro.

RESULTS

The intersection of DEGs and WGCNA confirmed 14 RRRGs, then six hub RRRGs were identified using LASSO. A key four genes (DUSP4, ADORA2B, SCGB2A1, and RIC3) risk score model was constructed and proved to be capable of independently estimating the prognosis of PC. There is no significant difference between risk score groups in various immune cell infiltration and response to immunotherapy. Although the low-risk group seemed to exhibit greater sensitivity to antitumor drugs, the four drugs (5-fluorouracil [5-FU], leucovorin, irinotecan, and oxaliplatin) currently used for PC patients had no statistical difference for the low- and high- group. The overexpression of RIC3 had a synergy effect with irradiation on inhibited malignant biological properties of PC cells, which was verified by detecting the proliferation ability, apoptosis rate, cell cycle distribution, and migration ability of PANC-1 cells.

CONCLUSIONS

We herein presented signature genes correlated with radioresistance in PC and established a risk score model competent in estimating patients' clinical outcomes and response to antitumor drugs. The above evidence could contribute to comprehending the mechanisms of radioresistance and identifying the underlying therapy targeting.

Combining immunoscore and tumor budding in colon cancer: an insightful prognostication based on the tumor-host interface

BACKGROUND

Tumor Budding (TB) and Immunoscore are independent prognostic markers in colon cancer (CC). Given their respective representation of tumor aggressiveness and immune response, we examined their combination in association with patient disease-free survival (DFS) in pTNM stage I-III CC.

METHODS

In a series of pTNM stage I-III CCs (n = 654), the Immunoscore was computed and TB detected automatically using a deep learning network. Two-tiered systems for both biomarkers were used with cut-offs of 25% and ten buds for Immunoscore and TB according to clinical guidelines, respectively. Associations of Immunoscore with TB with 5-year DFS were examined using Kaplan-Meier survival analysis in addition to multivariable modeling and relative contribution analysis using Cox regression.

RESULTS

Immunoscore and TB independently are prognostic with hazard ratio (HR) = 2.0, 95% confidence interval (CI) 1.4-2.8 and HR 2.5, with 95% CI 1.4-4.5, respectively; P value < 0.0001. By combining Immunoscore with TB, patients with Immunoscore Low, TB High tumors had a significantly poorer DFS (HR 5.6, 95% CI 2.6-12.0; P value < 0.0001) than those with Immunoscore High, TB Low tumors. The combined Immunoscore with TB score was independently prognostic (P value = 0.009) in comparison to N-stage, T-stage, and MSI. Immunoscore with TB had the highest relative contribution (35%) to DFS in pTNM stage I-II CCs.

CONCLUSIONS

The association of Immunoscore and TB with patient survival suggests that both biomarkers are complementary and should be interpreted in combination to identify high-risk Stage I-II patients who should be considered for adjuvant therapy or further diagnostic testing.

From Subtypes to Solutions: Integrating CMS Classification with Precision Therapeutics in Colorectal Cancer

OPINION STATEMENT

The biological heterogeneity of colorectal cancer makes its molecular characteristics essential for therapeutic decision-making and prognostic evaluation. Recent advancements in consensus molecular subtyping, based on gene expression profiling, have provided deeper insights into the heterogeneity of CRC. CMS1, known as the immune subtype, is characterized by robust immune activity and microsatellite instability. CMS2, the canonical subtype, exhibits significant activation of the WNT and MYC signaling pathways. CMS3, the metabolic subtype, features unique metabolic dysregulations. CMS4, the mesenchymal subtype, is recognized for its stromal invasion and angiogenesis, which are associated with a poorer prognosis. This review delivers a thorough analysis of the biological and clinical responses of each CMS subtype in colorectal cancer, highlighting their therapeutic vulnerabilities. It integrates data and clinical trial results to suggest potential new therapies for each subtype. The goal is to improve therapeutic efficacy, minimize treatment disparities, and offer CRC patients more precise treatment options.

Identification of Key Genes in Fetal Gut Development at Single-Cell Level by Exploiting Machine Learning Techniques

The study of fetal gut development is critical due to its substantial influence on immediate neonatal and long-term adult health. Current research largely focuses on microbiome colonization, gut immunity, and barrier function, alongside the impact of external factors on these phenomena. Limited research has been dedicated to the categorization of developing fetal gut cells. Our study aimed to enhance our understanding of fetal gut development by employing advanced machine-learning techniques on single-cell sequencing data. This dataset consisted of 62,849 samples, each characterized by 33,694 distinct gene features. Four feature ranking algorithms were utilized to sort features according to their significance, resulting in four feature lists. Then, these lists were fed into an incremental feature selection method to extract essential genes, classification rules, and build efficient classifiers. Several important genes were recognized by multiple feature ranking algorithms, such as FGG, MDK, RBP1, RBP2, IGFBP7, and SPON2. These features were key in differentiating specific developing intestinal cells, including epithelial, immune, mesenchymal, and vasculature cells of the colon, duo jejunum, and ileum cells. The classification rules showed special gene expression patterns on some intestinal cell types and the efficient classifiers can be useful tools for identifying intestinal cells.

Preferential activation of type I interferon-mediated antitumor inflammatory signaling by CuS/MnO2/diAMP nanoparticles enhances anti-PD-1 therapy for sporadic colorectal cancer

Converting the "cold" tumor microenvironment (TME) to a "hot" milieu has become the prevailing approach for enhancing the response of immune-excluded/immunosuppressed colorectal cancer (CRC) patients to immune checkpoint blockade (ICB) therapy. During this process, inflammation accompanied by different kinds of chemokines/cytokines inevitably occurs. However, some activated inflammatory signals exhibit protumor potency. Therefore, strategies that preferentially activate antitumor inflammatory signaling rather than tumor-promoting signaling need to be developed. Herein, we constructed a STING agonist-loaded CuS/MnO2 bimetallic nanosystem, termed diAMP-BCM. BCM with an optimized Cu/Mn ratio efficiently promoted the activation of proinflammatory signaling, and in combination with the STING agonist diAMP, diAMP-BCM controllably activated tumoricidal inflammatory signaling in APCs. DiAMP-BCM can efficiently generate ROS and promote the activation of STING, which induces the apoptosis of cancer cells and promotes the recruitment of monocytes while facilitating the polarization of macrophages and maturation of DCs. MC38 and CT26 CRC models were established to evaluate the in vivo antitumor effects of diAMP-BCM. Combined with ICB therapy, diAMP-BCM enables the rebuilding of tumor milieus with efficient tumor growth inhibition and alleviation of T-cell exhaustion, particularly in distal tumors, in sporadic colorectal cancer therapy. This study established a nanoplatform to promote the preferential activation of antitumor inflammatory signaling, rebuild the T-cell repertoire and alleviate T-cell exhaustion to enhance cancer ICB immunotherapy.

Lynch syndrome-associated and sporadic microsatellite unstable colorectal cancers: different patterns of clonal evolution yield highly similar tumours

Microsatellite unstable colorectal cancer (MSI-CRC) can arise through germline mutations in mismatch repair (MMR) genes in individuals with Lynch syndrome (LS), or sporadically through promoter methylation of the MMR gene MLH1. Despite the different origins of hereditary and sporadic MSI tumours, their genomic features have not been extensively compared. A prominent feature of MMR-deficient genomes is the occurrence of many indels in short repeat sequences, an understudied mutation type due to the technical challenges of variant calling in these regions. In this study, we performed whole genome sequencing and RNA-sequencing on 29 sporadic and 14 hereditary MSI-CRCs. We compared the tumour groups by analysing genome-wide mutation densities, microsatellite repeat indels, recurrent protein-coding variants, signatures of single base, doublet base, and indel mutations, and changes in gene expression. We show that the mutational landscapes of hereditary and sporadic MSI-CRCs, including mutational signatures and mutation densities genome-wide and in microsatellites, are highly similar. Only a low number of differentially expressed genes were found, enriched to interferon-γ regulated immune response pathways. Analysis of the variance in allelic fractions of somatic variants in each tumour group revealed higher clonal heterogeneity in sporadic MSI-CRCs. Our results suggest that the differing molecular origins of MMR deficiency in hereditary and sporadic MSI-CRCs do not result in substantial differences in the mutational landscapes of these tumours. The divergent patterns of clonal evolution between the tumour groups may have clinical implications, as high clonal heterogeneity has been associated with decreased tumour immunosurveillance and reduced responsiveness to immunotherapy.

SIR-EN-New Biomarker for Identifying Patients at Risk of Endometrial Carcinoma in Abnormal Uterine Bleeding at Menopause

OBJECTIVE

This study aimed to evaluate the efficacy of a new biomarker, termed SIR-En, in identifying patients at risk of endometrial carcinoma among those presenting with abnormal uterine bleeding during menopause.

MATERIAL AND METHODS

A retrospective case-control analysis was conducted on 242 women with menopausal abnormal uterine bleeding and endometrial thickness ≥ 4 mm. Peripheral blood samples were collected within 7 days before histological diagnosis. systemic inflammatory reaction (SIR) indices were calculated, including NLR, MLR, PLR, and SII. SIR-En was derived by multiplying SII and endometrial thickness. Statistical analyses, including multivariate linear regression and ROC curve analysis, were performed to assess the diagnostic capability of SIR-En.

RESULTS

Patients were categorized into endometrial hyperplasia (50 patients) and endometrial cancer (192 patients) groups. The SIR-En index was significantly higher in the carcinoma group (8710 vs. 6420; p = 0.003). The ROC curve for SIR-En had an AUC of 0.6351 (95% CI: 0.5579-0.7121). Using Youden's method, the optimal SIR-En cutoff was 13,806, showing a specificity of 0.940 and a positive predictive value of 0.957.

CONCLUSIONS

Combining systemic inflammatory indices with endometrial thickness, the SIR-En index can effectively distinguish between endometrial hyperplasia and carcinoma in menopausal women with abnormal uterine bleeding. Despite the retrospective design, the identified cutoff's high specificity and positive predictive value support its potential utility in clinical practice. Further prospective studies are required to validate these findings and optimize clinical application.

Influence of the gut microbiota on immune cell interactions and cancer treatment

The tumour microenvironment represents a novel frontier in oncological research. Over the past decade, accumulating evidence has underscored the importance of the tumour microenvironment (TME), including tumour cells, stromal cells, immune cells, and various secreted factors, which collectively influence tumour growth, invasion, and responses to therapeutic agents. Immune cells within the TME are now widely acknowledged to play pivotal roles in tumour development and treatment. While some perspectives have posited that immune cells within the TME facilitate tumour progression and confer resistance to therapeutic interventions, contrasting conclusions also exist. Affirmative and negative conclusions appear to be context dependent, and a unified consensus has yet to be reached. The burgeoning body of research on the relationship between the gut microbiota and tumours in recent years has led to a growing understanding. Most studies have indicated that specific components of the gut microbiota, such as unique bacterial communities or specific secretory factors, play diverse roles in regulating immune cells within the TME, thereby influencing the prognosis and outcomes of cancer treatments. A detailed understanding of these factors could provide novel insights into the TME and cancer therapy. In this study, we aimed to synthesise information on the interactions between the gut microbiota and immune cells within the TME, providing an in-depth exploration of the potential guiding implications for future cancer therapies.

A new strategy for immunotherapy of microsatellite-stable (MSS)-type advanced colorectal cancer: Multi-pathway combination therapy with PD-1/PD-L1 inhibitors

Colorectal cancer (CRC) is a frequent gastrointestinal malignancy with high rates of morbidity and mortality; 85% of these tumours are proficient mismatch repair (pMMR)-microsatellite instability-low (MSI-L)/microsatellite stable (MSS) CRC known as 'cold' tumours that are resistant to immunosuppressive drugs. Monotherapy with programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors is ineffective for treating MSS CRC, making immunotherapy for MSS CRC a bottleneck. Recent studies have found that the multi-pathway regimens combined with PD-1/PD-L1 inhibitors can enhance the efficacy of anti-PD-1/PD-L1 in MSS CRC by increasing the number of CD8+ T cells, upregulating PD-L1 expression and improving the tumour microenvironment. This paper reviews the research progress of PD-1/PD-L1 inhibitors in combination with cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) inhibitors, oncolytic virus, intestinal flora, antiangiogenic agents, chemotherapy, radiotherapy and epigenetic drugs for the treatment of pMMR-MSI-L/MSS CRC.

Spatial effects of infiltrating T cells on neighbouring cancer cells and prognosis in stage III CRC patients

Colorectal cancer (CRC) is one of the most frequently occurring cancers, but prognostic biomarkers identifying patients at risk of recurrence are still lacking. In this study, we aimed to investigate in more detail the spatial relationship between intratumoural T cells, cancer cells, and cancer cell hallmarks as prognostic biomarkers in stage III colorectal cancer patients. We conducted multiplexed imaging of 56 protein markers at single-cell resolution on resected fixed tissue from stage III CRC patients who received adjuvant 5-fluorouracil (5FU)-based chemotherapy. Images underwent segmentation for tumour, stroma, and immune cells, and cancer cell 'state' protein marker expression was quantified at a cellular level. We developed a Python package for estimation of spatial proximity, nearest neighbour analysis focusing on cancer cell-T-cell interactions at single-cell level. In our discovery cohort (Memorial Sloan Kettering samples), we processed 462 core samples (total number of cells: 1,669,228) from 221 adjuvant 5FU-treated stage III patients. The validation cohort (Huntsville Clearview Cancer Center samples) consisted of 272 samples (total number of cells: 853,398) from 98 stage III CRC patients. While there were trends for an association between the percentage of cytotoxic T cells (across the whole cancer core), it did not reach significance (discovery cohort: p = 0.07; validation cohort: p = 0.19). We next utilised our region-based nearest neighbour approach to determine the spatial relationships between cytotoxic T cells, helper T cells, and cancer cell clusters. In both cohorts, we found that shorter distance between cytotoxic T cells, T helper cells, and cancer cells was significantly associated with increased disease-free survival. An unsupervised trained model that clustered patients based on the median distance between immune cells and cancer cells, as well as protein expression profiles, successfully classified patients into low-risk and high-risk groups (discovery cohort: p = 0.01; validation cohort: p = 0.003). © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The Importance of Predictive Biomarkers and Their Correlation with the Response to Immunotherapy in Solid Tumors-Impact on Clinical Practice

Background/Objectives: Immunotherapy has changed the therapeutic approach for various solid tumors, especially lung tumors, malignant melanoma, renal and urogenital carcinomas, demonstrating significant antitumor activity, with tolerable safety profiles and durable responses. However, not all patients benefit from immunotherapy, underscoring the need for predictive biomarkers that can identify those most likely to respond to treatment. Methods: The integration of predictive biomarkers into clinical practice for immune checkpoint inhibitors (ICI) holds great promise for personalized cancer treatment. Programmed death ligand 1 (PD-L1) expression, tumor mutational burden (TMB), microsatellite instability (MSI), gene expression profiles and circulating tumor DNA (ctDNA) have shown potential in predicting ICI responses across various cancers. Results: Challenges such as standardization, validation, regulatory approval, and cost-effectiveness must be addressed to realize their full potential. Predictive biomarkers are crucial for optimizing the clinical use of ICIs in cancer therapy. Conclusions: While significant progress has been made, further research and collaboration among clinicians, researchers, and regulatory institutes are essential to overcome the challenges of clinical implementation. However, little is known about the relationship between local and systemic immune responses and the correlation with response to oncological therapies and patient survival.

T cell factor 1 (TCF-1) defines T cell differentiation in colorectal cancer

The presence of precursor to exhausted (Tpex) CD8+ T cells is important to maintain robust immunity following treatment with immune checkpoint inhibition (ICI). Impressive responses to ICI are emerging in patients with stage II-III mismatch repair (MMR)-deficient (dMMR) colorectal cancer (CRC). We found 64% of dMMR and 15% of mismatch repair-proficient (pMMR) stage III CRCs had a high frequency of tumor infiltrating lymphocytes (TIL-hi). Furthermore, expression of TCF-1 (Tcf7) by CD8+ T cells predicted improved patient prognosis and Tpex cells (CD3+CD8+TCF-1+PD-1+) were abundant within lymphoid aggregates of stage III CRCs. In contrast, CD3+CD8+TCF-1-PD-1+ cells were more abundant at the invasive front and tumor core, while γδ T cells were equally abundant in all tumor areas. Interestingly, no differences in the frequency of Tpex cells were observed between TIL-hi dMMR and TIL-hi pMMR CRCs. Therefore, Tpex cell function and ICI response rates in TIL-hi CRC warrants further investigation.

Mechanisms of metastatic colorectal cancer

Despite extensive research and improvements in understanding colorectal cancer (CRC), its metastatic form continues to pose a substantial challenge, primarily owing to limited therapeutic options and a poor prognosis. This Review addresses the emerging focus on metastatic CRC (mCRC), which has historically been under-studied compared with primary CRC despite its lethality. We delve into two crucial aspects: the molecular and cellular determinants facilitating CRC metastasis and the principles guiding the evolution of metastatic disease. Initially, we examine the genetic alterations integral to CRC metastasis, connecting them to clinically marked characteristics of advanced CRC. Subsequently, we scrutinize the role of cellular heterogeneity and plasticity in metastatic spread and therapy resistance. Finally, we explore how the tumour microenvironment influences metastatic disease, emphasizing the effect of stromal gene programmes and the immune context. The ongoing research in these fields holds immense importance, as its future implications are projected to revolutionize the treatment of patients with mCRC, hopefully offering a promising outlook for their survival.

Non-invasive CT radiomic biomarkers predict microsatellite stability status in colorectal cancer: a multicenter validation study

BACKGROUND

Microsatellite instability (MSI) status is a strong predictor of response to immunotherapy of colorectal cancer. Radiogenomic approaches promise the ability to gain insight into the underlying tumor biology using non-invasive routine clinical images. This study investigates the association between tumor morphology and the status of MSI versus microsatellite stability (MSS), validating a novel radiomic signature on an external multicenter cohort.

METHODS

Preoperative computed tomography scans with matched MSI status were retrospectively collected for 243 colorectal cancer patients from three hospitals: Seoul National University Hospital (SNUH); Netherlands Cancer Institute (NKI); and Fondazione IRCCS Istituto Nazionale dei Tumori, Milan Italy (INT). Radiologists delineated primary tumors in each scan, from which radiomic features were extracted. Machine learning models trained on SNUH data to identify MSI tumors underwent external validation using NKI and INT images. Performances were compared in terms of area under the receiving operating curve (AUROC).

RESULTS

We identified a radiomic signature comprising seven radiomic features that were predictive of tumors with MSS or MSI (AUROC 0.69, 95% confidence interval [CI] 0.54-0.84, p = 0.018). Integrating radiomic and clinical data into an algorithm improved predictive performance to an AUROC of 0.78 (95% CI 0.60-0.91, p = 0.002) and enhanced the reliability of the predictions.

CONCLUSION

Differences in the radiomic morphological phenotype between tumors MSS or MSI could be detected using radiogenomic approaches. Future research involving large-scale multicenter prospective studies that combine various diagnostic data is necessary to refine and validate more robust, potentially tumor-agnostic MSI radiogenomic models.

RELEVANCE STATEMENT

Noninvasive radiomic signatures derived from computed tomography scans can predict MSI in colorectal cancer, potentially augmenting traditional biopsy-based methods and enhancing personalized treatment strategies.

KEY POINTS

Noninvasive CT-based radiomics predicted MSI in colorectal cancer, enhancing stratification. A seven-feature radiomic signature differentiated tumors with MSI from those with MSS in multicenter cohorts. Integrating radiomic and clinical data improved the algorithm's predictive performance.

Multiplex spatial omics reveals changes in immune-epithelial crosstalk during inflammation and dysplasia development in chronic IBD patients

Patients with long-standing inflammatory bowel disease (IBD) face an increased risk of developing colitis-associated cancer (CAC). Although IBD-induced prolonged inflammation seems to be involved in CAC pathogenesis, the specific molecular changes that contribute remain unknown. Here, we applied digital spatial RNA profiling, RNAscope, and imaging mass cytometry to examine paired uninflamed, inflamed, and early dysplastic mucosa of patients with IBD. We observed robust type 3 (IL-17) responses during inflammation, accompanied by elevated JAK-STAT signaling and phosphorylated STAT3 (P-STAT3) levels, with both inflamed and dysplastic mucosa displaying immune cell activation. Higher stromal P-STAT3 was detected in uninflamed and inflamed mucosa of patients who eventually developed dysplasia. CD8a+ T cells did not infiltrate inflamed or dysplastic epithelial regions in these patients, while control patients showed elevated CD8a in inflamed mucosa. Our study reveals distinct inflammatory patterns throughout CAC development, marked by an activated IL-17 pathway, engaged STAT3, and diminished cytotoxic T cell infiltration.

Lymphocyte Infiltration Score and Spatial Characteristics Refined the Prognosis and Denosumab Treatment Responsiveness Indicators for Giant Cell Tumor of Bone

PURPOSE

The prognostic value of lymphocyte infiltration score (LIS) and its nearest neighbor distance to tumor cells (NNDTC) in giant cell tumor of bone (GCTB) is currently not well established. This study aims to characterize LIS and NNDTC and examine their correlation with denosumab treatment responsiveness, clinicopathologic features, and patient prognosis.

METHODS

Using multiplexed quantitative immunofluorescence, LIS was evaluated in 253 tumor specimens, whereas NNDTC was computed using HALO software. Subsequently, we analyzed the association of these parameters with patient outcomes (progression-free survival [PFS] and overall survival [OS]), clinicopathologic features, and denosumab treatment responsiveness.

RESULTS

Low LIS was indicative of both poor PFS and OS (both P < .001). In addition, LIS was significantly associated with sex (P = .046), Enneking staging (P < .001), Ki-67 expression (P = .007), and denosumab treatment responsiveness (P = .005). Lower CD8+ (tumor interior [TI]) NNDTC, and CD3+ (TI) NNDTC were associated with worse PFS (P = .003 and .038, respectively), whereas lower CD8+ (TI) NNDTC was associated with worse OS (P = .001), but CD8+ (tumor infiltrating margin) NNDTC had the opposite effect (P = .002). Moreover, NNDTC showed a correlation with several clinicopathologic features. Importantly, LIS outperformed Enneking and Campanacci staging systems in predicting the clinical outcomes of GCTB.

CONCLUSION

These findings suggest that LIS is a reliable predictive tool for clinically relevant outcomes and response to denosumab therapy in patients with GCTB. These parameters may prove to be useful in guiding prognostic risk stratification and therapeutic optimization for patients.

B7-H4 reduces the infiltration of CD8+T cells and induces their anti-tumor dysfunction in gliomas

B7-H4 is a promising immune checkpoint molecule in tumor immunotherapy. Our previous study showed that high B7-H4 expression was strongly correlated with deficiency in tumor infiltrated lymphocytes (TILs) in glioma patients. On this basis, we investigated the impact of B7-H4 on CD8+TILs in gliomas and the associated molecular mechanism here. B7-H4-positive tumor samples (n=129) from our glioma cohort were used to assess B7-H4 expression and CD8+TIL quantification by immunohistochemistry. CD8+TILs from five glioma patients cultured with B7-H4 protein were used to evaluate anti-tumor dysfunction by flow cytometry and ELISpot. An orthotopic murine glioma model was used to investigate the role of B7-H4 in glioma CD8+TILs by immunohisto- chemistry and flow cytometry. CD8+TILs from glioma patients cultured with B7-H4 protein were used to explore the potential molecular mechanism by RNA sequencing and western blot. Our results showed that glioma CD8+TIL density was negatively correlated with B7-H4 expression both in glioma patient cohort (P < 0.05) and orthotopic glioma murine model (P < 0.01). B7-H4 also lowered the expression of CD137 and CD103 (P < 0.05 for both) in glioma CD8+TILs and reduced their secretion of the anti-tumor cytokines IFN-γ and TNF-α (P < 0.01 for both) in a dose-dependent manner. Furthermore, B7-H4 was found to induce early dysfunction of glioma CD8+TILs by downregulating the phosphorylation of AKT and eNOS (P < 0.05 for both). In conclusion, B7-H4 reduced the infiltration of glioma CD8+TILs and induced an anti-tumor dysfunction phenotype. B7-H4 may also impair the anti-tumor function of glioma CD8+TILs via the AKT-eNOS pathway. These results indicated that B7-H4 may serve as a potential target in future glioma immunotherapy.

GJA4 expressed on cancer associated fibroblasts (CAFs)-A 'promoter' of the mesenchymal phenotype

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide. Connexin is a transmembrane protein involved in gap junctions (GJs) formation. Our previous study found that connexin 37 (Cx37), encoded by gap junction protein alpha 4 (GJA4), expressed on fibroblasts acts as a promoter of CRC and is closely related to epithelial-mesenchymal transition (EMT) and tumor immune microenvironment. However, to date, the mechanism concerning the malignancy of GJA4 in tumor stroma has not been studied.

METHODS

Hematoxylin-eosin (HE) and immunohistochemical (IHC) staining were used to validate the expression and localization of GJA4. Using single-cell analysis, enrichment analysis, spatial transcriptomics, immunofluorescence staining (IF), Sirius red staining, wound healing and transwell assays, western blotting (WB), Cell Counting Kit-8 (CCK8) assay and in vivo experiments, we investigated the possible mechanisms of GJA4 in promoting CRC.

RESULTS

We discovered that in CRC, GJA4 on fibroblasts is involved in promoting fibroblast activation and promoting EMT through a fibroblast-dependent pathway. Furthermore, GJA4 may act synergistically with M2 macrophages to limit T cell infiltration by stimulating the formation of an immune-excluded desmoplasic barrier. Finally, we found a significantly correlation between GJA4 and pathological staging (P < 0.0001) or D2 dimer (R = 0.03, P < 0.05).

CONCLUSION

We have identified GJA4 expressed on fibroblasts is actually a promoter of the tumor mesenchymal phenotype. Our findings suggest that the interaction between GJA4+ fibroblasts and M2 macrophages may be an effective target for enhancing tumor immunotherapy.

A novel risk scoring system predicts overall survival of hepatocellular carcinoma using cox proportional hazards machine learning method

BACKGROUND

Robust and practical prognosis prediction models for hepatocellular carcinoma (HCC) patients play crucial roles in personalized precision medicine.

MATERIAL AND METHODS

We recruited two independent HCC cohorts (discovery cohort and validation cohort), totally consisting of 222 HCC patients undergone surgical resection. We quantified the expressions of immune-related proteins (CD8, CD68, CD163, PD-1 and PD-L1) in paired HCC tissues and non-tumor liver tissues from these HCC patients using immunohistochemistry (mIHC) assays. We constructed the HCC prognosis prediction model using five different machine learning methods based on the patients in the discovery cohort, such as Cox proportional hazards (CoxPH).

RESULTS

We identified 19 features that were associated with overall survival of HCC patients in the discovery cohort (p < 0.1), such as immune-related features CD68+ and CD8+ cell infiltration. We constructed five HCC prognosis prediction models using five different machine learning methods. Among the five different machine learning models, the CoxPH model achieved the best performance (area under the curve [AUC], 0.839; C-index, 0.779). According to the risk score from CoxPH model, we divided HCC patients into high-risk group/low-risk group. In both discovery cohort and validation cohort, the patients in low-risk group showed longer overall survival compared with those in high-risk group (p = 1.8 × 10-7 and 3.4 × 10-5, respectively). Moreover, our novel scoring system efficiently predicted the 6, 12, and 18 months survival rate of HCC patients with AUC >0.75 in both discovery cohort and validation cohort. In addition, we found that the scoring system could also distinguish the patients with high/low risks of relapse in both discovery cohort and validation cohort (p = 0.00015 and 0.00012).

CONCLUSION

The novel CoxPH-based risk scoring model on clinical, laboratory-testing and immune-related features showed high prediction efficiencies for overall survival and recurrence of HCCs undergone surgical resection. Our results may be helpful to optimize clinical follow-up or therapeutic interventions.

Improving the efficiency of immune checkpoint inhibitors for metastatic pMMR/MSS colorectal cancer: Options and strategies

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment and been extensively used for patients with metastastic colorectal cancer (mCRC), especially those harboring deficient mismatch repair/ microsatellite instability (dMMR/MSI). However, the majority of mCRC are classified as proficient mismatch repair/microsatellite stability(pMMR/MSS) type characterized by a cold immune microenvironment, rendering them generally unresponsive to ICIs. How to improve the efficacy of ICIs for these patients is an important issue to be solved. On the one hand, it is urgent to discover the predictive biomarkers and clinical characteristics associated with effectiveness and expand the subset of pMMR/MSS mCRC patients who benefit from ICIs. Additionally, combined strategies are being explored to modulate the immune microenvironment of pMMR/MSS CRC and facilitate the conversion of cold tumors into hot tumors. In this review, we have focused on the recent advancements in the predictive biomarkers and combination therapeutic strategies with ICIs for pMMR/MSS mCRC.

Defining clinically useful biomarkers of immune checkpoint inhibitors in solid tumours

Although more than a decade has passed since the approval of immune checkpoint inhibitors (ICIs) for the treatment of melanoma and non-small-cell lung, breast and gastrointestinal cancers, many patients still show limited response. US Food and Drug Administration (FDA)-approved biomarkers include programmed cell death 1 ligand 1 (PDL1) expression, microsatellite status (that is, microsatellite instability-high (MSI-H)) and tumour mutational burden (TMB), but these have limited utility and/or lack standardized testing approaches for pan-cancer applications. Tissue-based analytes (such as tumour gene signatures, tumour antigen presentation or tumour microenvironment profiles) show a correlation with immune response, but equally, these demonstrate limited efficacy, as they represent a single time point and a single spatial assessment. Patient heterogeneity as well as inter- and intra-tumoural differences across different tissue sites and time points represent substantial challenges for static biomarkers. However, dynamic biomarkers such as longitudinal biopsies or novel, less-invasive markers such as blood-based biomarkers, radiomics and the gut microbiome show increasing potential for the dynamic identification of ICI response, and patient-tailored predictors identified through neoadjuvant trials or novel ex vivo tumour models can help to personalize treatment. In this Perspective, we critically assess the multiple new static, dynamic and patient-specific biomarkers, highlight the newest consortia and trial efforts, and provide recommendations for future clinical trials to make meaningful steps forwards in the field.

Spatial distribution pattern of immune cells is associated with patient prognosis in colorectal cancer

BACKGROUND

The spatial context of tumor-infiltrating immune cells (TIICs) is important in predicting colorectal cancer (CRC) patients' clinical outcomes. However, the prognostic value of the TIIC spatial distribution is unknown. Thus, we aimed to investigate the association between TIICs in situ and patient prognosis in a large CRC sample.

METHODS

We implemented multiplex immunohistochemistry staining technology in 190 CRC samples to quantify 14 TIIC subgroups in situ. To delineate the spatial relationship of TIICs to tumor cells, tissue slides were segmented into tumor cell and microenvironment compartments based on image recognition technology, and the distance between immune and tumor cells was calculated by implementing the computational pipeline phenoptr.

RESULTS

MPO+ neutrophils and CD68+IDO1+ tumor-associated macrophages (TAMs) were enriched in the epithelial compartment, and myeloid lineage cells were located nearest to tumor cells. Except for CD68+CD163+ TAMs, other cells were all positively associated with favorable prognosis. The prognostic predictive power of TIICs was highly related to their distance to tumor cells. Unsupervised clustering analysis divided colorectal cancer into three subtypes with distinct prognostic outcomes, and correlation analysis revealed the synergy among B cells, CD68+IDO1+TAMs, and T lineage cells in producing an effective immune response.

CONCLUSIONS

Our study suggests that the integration of spatial localization with TIIC abundance is important for comprehensive prognostic assessment.

Prognostic and Predictive Value of Immunoscore in Stage III Colorectal Cancer: Pooled Analysis of Cases From the SCOT and IDEA-HORG Studies

PURPOSE

Immunoscore (IS) is prognostic in stage III colorectal cancer (CRC) and may predict benefit of duration (6 v 3 months) of adjuvant infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) chemotherapy. We sought to determine IS prognostic and predictive value in stage-III CRC treated with adjuvant FOLFOX or oral capecitabine and infusional oxaliplatin (CAPOX) in the SCOT and IDEA-HORG trials.

METHODS

Three thousand sixty-one cases had tumor samples, of which 2,643 (1,792 CAPOX) were eligible for IS testing. Predefined cutoffs (IS-Low and IS-High) were used to classify cases into two groups for analysis of disease-free survival (3-year DFS) and multivariable-adjusted hazard ratios (mvHRs) by Cox regression.

RESULTS

IS was determined in 2,608 (99.5%) eligible cases, with 877 (33.7%) samples classified as IS-Low. IS-Low tumors were more commonly high-risk (T4 and/or N2; 52.9% IS-Low v 42.2% IS-High; P < .001) and in younger patients (P = .024). Patients with IS-Low tumors had significantly shorter DFS in the CAPOX, FOLFOX, and combined cohorts (mvHR, 1.52 [95% CI, 1.28 to 1.82]; mvHR, 1.58 [95% CI, 1.22 to 2.04]; and mvHR, 1.55 [95% CI, 1.34 to 1.79], respectively; P < .001 all comparisons), regardless of sex, BMI, clinical risk group, tumor location, treatment duration, or chemotherapy regimen. IS prognostic value was greater in younger (≤65 years) than older (>65 years) patients in the CAPOX cohort (mvHR, 1.92 [95% CI, 1.50 to 2.46] v 1.28 [95% CI, 1.01 to 1.63], PINTERACTION = .026), and in DNA mismatch repair proficient than deficient mismatch repair disease (mvHR, 1.68 [95% CI, 1.41 to 2.00] v 0.67 [95% CI, 0.30 to 1.49], PINTERACTION = .03), although these exploratory analyses were uncorrected for multiple testing. Adding IS to a model containing all clinical variables significantly improved prediction of DFS (likelihood ratio test, P < .001) regardless of MMR status.

CONCLUSION

IS is prognostic in stage III CRC treated with FOLFOX or CAPOX, including within clinically relevant tumor subgroups. Possible variation in IS prognostic value by age and MMR status, and prediction of benefit from extended adjuvant therapy merit validation.

Interaction of microbiota, mucosal malignancies, and immunotherapy-Mechanistic insights

The microbiome has emerged as a crucial modulator of host-immune interactions and clearly impacts tumor development and therapy efficacy. The microbiome is a double-edged sword in cancer development and therapy as both pro-tumorigenic and anti-tumorigenic bacterial taxa have been identified. The staggering number of association-based studies in various tumor types has led to an enormous amount of data that makes it difficult to identify bacteria that promote tumor development or modulate therapy efficacy from bystander bacteria. Here we aim to comprehensively summarize the current knowledge of microbiome-host immunity interactions and cancer therapy in various mucosal tissues to find commonalities and thus identify potential functionally relevant bacterial taxa. Moreover, we also review recent studies identifying specific bacteria and mechanisms through which the microbiome modulates cancer development and therapy efficacy.

Pembrolizumab Plus mFOLFOX7 or FOLFIRI for Microsatellite Stable/Mismatch Repair-Proficient Metastatic Colorectal Cancer: KEYNOTE-651 Cohorts B and D

BACKGROUND

The phase 1b KEYNOTE-651 study evaluated pembrolizumab plus chemotherapy in microsatellite stable or mismatch repair-proficient metastatic colorectal cancer.

PATIENTS AND METHODS

Patients with microsatellite stable or mismatch repair-proficient metastatic colorectal cancer received pembrolizumab 200 mg every 3 weeks plus 5-fluorouracil, leucovorin, oxaliplatin (previously untreated; cohort B) or 5-fluorouracil, leucovorin, irinotecan (previously treated with fluoropyrimidine plus oxaliplatin; cohort D) every 2 weeks. Primary end point was safety; investigator-assessed objective response rate per RECIST v1.1 was secondary and biomarker analysis was exploratory.

RESULTS

Thirty-one patients were enrolled in cohort B and 32 in cohort D; median follow-up was 30.2 and 33.5 months, respectively. One dose-limiting toxicity (grade 3 small intestine obstruction) occurred in cohort D. In cohort B, grade 3 or 4 treatment-related adverse events (AEs) occurred in 18 patients (58%), most commonly neutropenia and decreased neutrophil count (n = 5 each). In cohort D, grade 3 or 4 treatment-related AEs occurred in 17 patients (53%), most commonly neutropenia (n = 7). No grade 5 treatment-related AEs occurred. Objective response rate was 61% in cohort B (KRAS wildtype: 71%; KRAS mutant: 53%) and 25% in cohort D (KRAS wildtype: 47%; KRAS mutant: 6%). In both cohorts, PD-L1 combined positive score and T-cell-inflamed gene expression profiles were higher and HER2 expression was lower in responders than nonresponders. No association between tumor mutational burden and response was observed.

CONCLUSION

Pembrolizumab plus 5-fluorouracil, leucovorin, oxaliplatin/5-fluorouracil, leucovorin, irinotecan demonstrated an acceptable AE profile. Efficacy data appeared comparable with current standard of care (including by KRAS mutation status). Biomarker analyses were hypothesis-generating, warranting further exploration.

CLINICALTRIALS

GOV IDENTIFIER

ClinicalTrials.gov; NCT03374254.

Immunotherapy in Colorectal Cancer - Finding the Achilles' Heel

AbstractColorectal cancer treatment has evolved considerably in the last decade with the development of immunotherapies. Immune checkpoint inhibitor therapies have brisk and durable responses in patients with advanced microsatellite instability-high colorectal cancer, both surgically resectable and unresectable; however, patients with microsatellite stable colorectal cancer in general do not respond to the same therapy. Emerging evidence shows that immune checkpoint inhibitors may elicit responses in subsets of patients with microsatellite stable colorectal cancer, especially when combined with other anticancer agents that can modulate the tumor microenvironment. Therefore, rationally designed therapeutic combinations involving immune checkpoint inhibitors, as well as the development of predictive biomarkers for optimal patient selection, have emerged as two key areas of active research. In addition, other immunotherapeutic agents such as cell-based therapies and bispecific T-cell engagers are beginning to be studied in preclinical and early-phase settings. Although by no means a universal treatment strategy, immunotherapy can elicit responses in microsatellite stable colorectal cancer and further research is needed to extend their benefit to patients with microsatellite stable colorectal cancer. Here, we review the current state of immunotherapeutic regimens for microsatellite stable colorectal cancer.

Resistance to immune checkpoint inhibitors in colorectal cancer with deficient mismatch repair/microsatellite instability: misdiagnosis, pseudoprogression and/or tumor heterogeneity?

Colorectal carcinoma (CRC) with deficiency of the deficient mismatch repair (dMMR) pathway/microsatellite instability (MSI) is characterized by a high mutation load and infiltration of immune cells in the tumor microenvironment. In agreement with these findings, clinical trials have demonstrated a significant activity of immune checkpoint inhibitors (ICIs) in dMMR/MSI metastatic CRC (mCRC) patients and, more recently, in CRC patients with early disease undergoing neoadjuvant therapy. However, despite high response rates and durable clinical benefits, a fraction of mCRC patients, up to 30%, showed progressive disease when treated with single agent anti-programmed cell death 1 (PD-1) antibody. This article discusses the three main causes that have been associated with early progression of dMMR/MSI mCRC patients while on treatment with ICIs, i.e., misdiagnosis, pseudoprogression and tumor heterogeneity. While pseudoprogression probably does not play a relevant role, data from clinical studies demonstrate that some dMMR/MSI CRC cases with rapid progression on ICIs may be misdiagnosed, underlining the importance of correct diagnostics. More importantly, evidence suggests that dMMR/MSI mCRC is a heterogeneous group of tumors with different sensitivity to ICIs. Therefore, we propose novel diagnostic and therapeutic strategies to improve the outcome of dMMR/MSI CRC patients.

Immunotherapy in the neoadjuvant treatment of gastrointestinal tumors: is the time ripe?

Immune checkpoint inhibitors (ICIs) revolutionized the management of mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) gastrointestinal (GI) cancers. Based on notable results observed in the metastatic setting, several clinical trials investigated ICIs as neoadjuvant treatment (NAT) for localized dMMR/MSI-H GI cancers, achieving striking results in terms of clinical and pathological responses and creating the opportunity to spare patients from neoadjuvant chemotherapy and/or radiotherapy and even surgical resection. Nevertheless, these impressive findings are mainly derived from small proof of concept phase II studies and there are still several open questions to address. Moreover, dMMR/MSI-H represents a limited subgroup accounting for less than 10% of GI cancers. Consequently, many efforts have been produced to investigate neoadjuvant ICIs also in mismatch repair-proficient/microsatellite stable (MSS) cancers, considering the potential synergistic effect in combining immune-targeted agents with standard therapies such as chemo and/or radiotherapy. However, results for combining ICIs to the standard of care in the unselected population are still unsatisfactory, without improvements in event-free survival in esophago-gastric adenocarcinoma for the addition of pembrolizumab to chemotherapy, and sometimes limited benefit in patients with locally advanced rectal cancer. Therefore, a major challenge will be to identify among the heterogenous spectrum of this disease, those patients that could take advantage of neoadjuvant immunotherapy and deliver the most effective treatment. In this review we discuss the rationale of NAT in GI malignancies, summarize the available evidence regarding the completed trials that evaluated this treatment strategy in both MSI-H and MSS tumors. Finally, we discuss ongoing studies and future perspectives to render neoadjuvant immunotherapy another arrow in the quiver for the treatment of locally advanced GI tumors.

New Insight into Intestinal Mast Cells Revealed by Single-Cell RNA Sequencing

Mast cells (MCs) are tissue-resident immune cells distributed in all tissues and strategically located close to blood and lymphatic vessels and nerves. Thanks to the expression of a wide array of receptors, MCs act as tissue sentinels, able to detect the presence of bacteria and parasites and to respond to different environmental stimuli. MCs originate from bone marrow (BM) progenitors that enter the circulation and mature in peripheral organs under the influence of microenvironment factors, thus differentiating into heterogeneous tissue-specific subsets. Even though MC activation has been traditionally linked to IgE-mediated allergic reactions, a role for these cells in other pathological conditions including tumor progression has recently emerged. However, several aspects of MC biology remain to be clarified. The advent of single-cell RNA sequencing platforms has provided the opportunity to understand MCs' origin and differentiation as well as their phenotype and functions within different tissues, including the gut. This review recapitulates how single-cell transcriptomic studies provided insight into MC development as well as into the functional role of intestinal MC subsets in health and disease.

An exosomes-related lncRNA prognostic model correlates with the immune microenvironment and therapy response in lung adenocarcinoma

Recent research highlights the significance of exosomes and long noncoding RNAs (lncRNAs) in cancer progression and drug resistance, but their role in lung adenocarcinoma (LUAD) is not fully understood. We analyzed 121 exosome-related (ER) mRNAs from the ExoBCD database, along with mRNA and lncRNA expression profiles of TCGA-LUAD using "DESeq2", "survival," "ConsensusClusterPlus," "GSVA," "estimate," "glmnet," "clusterProfiler," "rms," and "pRRophetic" R packages. This comprehensive approach included univariate cox regression, unsupervised consensus clustering, GSEA, functional enrichment analysis, and prognostic model construction. Our study identified 134 differentially expressed ER-lncRNAs, with 19 linked to LUAD prognosis. These ER-lncRNAs delineated two patient subtypes, one with poorer outcomes. Additionally, 286 differentially expressed genes were related to these ER-lncRNAs, 261 of which also correlated with LUAD prognosis. We constructed an ER-lncRNA-related prognostic model and calculated an ER-lncRNA-related risk score (ERS), revealing that a higher ERS correlates with poor overall survival in both the Meta cohort and two validation cohorts. The ERS potentially serves as an independent prognostic factor, and the prognostic model demonstrates superior predictive power. Notably, significant differences in the immune landscape were observed between the high- and low-ERS groups. Drug sensitivity analysis indicated varying responses to common chemotherapy drugs based on ERS stratification, with the high-ERS group showing greater sensitivity, except to rapamycin and erlotinib. Experimental validation confirmed that thymidine kinase 1 enhances lung cancer invasion, metastasis, and cell cycle progression. Our study pioneers an ER-lncRNA-related prognostic model for LUAD, proposing that ERS-based risk stratification could inform personalized treatment strategies to improve patient outcomes.