Tumour infiltrating lymphocyte status is superior to histological grade, DNA mismatch repair and BRAF mutation for prognosis of colorectal adenocarcinomas with mucinous differentiation

Identification and validation of a novel six-gene signature based on mucinous adenocarcinoma-related gene molecular typing in colorectal cancer

BACKGROUND AND OBJECTIVES

Colorectal mucinous adenocarcinoma (MAC) is a particular pathological type that has yet to be thoroughly studied. This study aims to investigate the characteristics of colorectal MAC-related genes in colorectal cancer (CRC), explore the role of MAC-related genes in accurately classifying CRC, and further construct a prognostic signature.

METHODS

CRC samples were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). MAC-related differentially expressed genes (DEGs) were analyzed in TCGA samples. Based on colorectal MAC-related genes, TCGA CRC samples were molecularly typed by the non-negative matrix factorization (NMF). According to the molecular subtype characteristics, the RiskScore signature was constructed through univariate Cox, the least absolute shrinkage and selection operator (LASSO), and multivariate Cox regression analyses. Clinical significance in CRC of the RiskScore signature was analyzed. A nomogram was further built based on the RiskScore signature.

RESULTS

From the colorectal MAC-related genes, three distinct molecular subtypes were identified. A RiskScore signature composed of six CRC subtype-related genes (CALB1, MMP1, HOXC6, ZIC2, SFTA2, and HYAL1) was constructed. Patients with high-RiskScores had the worse prognoses. RiskScores led to differences in gene mutation characteristics, antitumor drug sensitivity, and tumor microenvironment of CRC. A nomogram based on the signature was developed to predict the one-, three-, and five-year survival of CRC patients.

CONCLUSION

MAC-related genes were able to classify CRC. A RiskScore signature based on the colorectal MAC-related molecular subtype was constructed, which had important clinical significance for guiding the accurate stratification of CRC patients.

Immune checkpoint blockade therapy for BRAF mutant metastatic colorectal cancer: the efficacy, new strategies, and potential biomarkers

BRAF mutant metastatic colorectal cancer has long been considered a tumor with a poor prognosis and a poor response to chemotherapy. Despite the efficacy of targeted therapy with multi-targeted blockade of the mitogen-activated protein kinase (MAPK) signaling pathway has brought a glimmer of hope to this group of patients, the need to improve treatment efficacy remains unmet, especially for the microsatellite stability/DNA proficient mismatch repair (MSS/pMMR) subtype. BRAF mutant colorectal cancer patients with high microsatellite instability/DNA deficient mismatch repair (MSI-H/dMMR) have high tumor mutation burden and abundant neoantigen, who are deemed as ones that could receive expected efficacy from immunotherapy. Generally, it is believed that MSS/pMMR colorectal cancer is an immunologically "cold" tumor that is insensitive to immunotherapy. However, targeted therapy combined with immune checkpoint blockade therapy seems to bring light to BRAF mutant colorectal cancer patients. In this review, we provide an overview of clinical efficacy and evolving new strategies concerning immune checkpoint blockade therapy for both MSI-H/dMMR and MSS/pMMR BRAF mutant metastatic colorectal cancer and discuss the potential biomarkers in the tumor immune microenvironment for predicting immunotherapeutic response in BRAF mutant colorectal cancer.

Correlation of clinical, pathologic, and genetic parameters with intratumoral immune milieu in mucinous adenocarcinoma of the colon

Mucinous adenocarcinoma (MAD), the most common subtype of colonic adenocarcinoma (CA), requires >50% intratumoral mucin. There is limited data regarding the impact of MAD on key lymphocyte subsets and therapeutically critical immune elements. In this study we address: (1) the definition of MAD, (2) grading of MAD, and (3) the impact of MAD and extracellular mucin on intratumoral immune milieu. Estimation of the percentage of intratumoral mucin was performed by two pathologists. Tissue microarrays were stained for immune markers including CD8, CD163, PD-L1, FoxP3, β2 microglobulin, HLA class I, and HLA class II. Immunohistochemistry for BRAF V600E was performed. MMR status was determined on immunohistochemistry for MSH2, MSH6, MLH1, PMS2. Manual and automated HALO platforms were used for quantification. The 903 CAs included 62 (6.9%) MAD and 841 CA with ≤ 50% mucin. We identified 225 CAs with mucinous differentiation, defined by ≥10% mucin. On univariate analysis neither cut point, 50% (p = 0.08) and 10% (p = 0.08) mucin, correlated with disease-specific survival (DSS). There were no differences in key clinical, histological and molecular features between MAD and CA with mucinous differentiation. On univariate analysis of patients with MAD, tumor grade correlated with DSS (p = 0.0001) while MMR status did not (p = 0.86). There was no statistically significant difference in CD8 (P = 0.17) and CD163 (P = 0.05) positive immune cells between MAD and conventional CA. However, deficient (d) MMR MADs showed fewer CD8 (P = 0.0001), CD163 (P = 0.0001) and PD-L1 (P = 0.003) positive immune cells compared to proficient (p)MMR MADs, a finding also seen with at 10% mucin cut point. Although MAD does not impact DSS, this study raises the possibility that the immune milieu of dMMR MADs and tumors with > =10% mucin may differ from pMMR MADs and tumors with <10% mucin, a finding that may impact immune-oncology based therapeutics.

Establishment and validation of a postoperative predictive model for patients with colorectal mucinous adenocarcinoma

BACKGROUND

The aim of this study was to develop comprehensive and effective nomograms for predicting overall survival (OS) and cancer-specific survival (CSS) rates in patients with colorectal mucinous adenocarcinoma (CRMA).

METHODS

A total of 4711 CRMA patients who underwent radical surgery between 2010 and 2018 from the Surveillance, Epidemiology, and End Results (SEER) database were collected and randomized into development (n=3299) and validation (n=1412) cohorts at a ratio of 7:3 for model development and validation. OS and CSS nomograms were developed using the prognostic factors from the development cohort after multivariable Cox regression analysis. The performance of the nomograms was evaluated using Harrell's concordance index (C-index), calibration diagrams, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA).

RESULTS

The study included 4711 patients. Multivariate Cox regression analysis demonstrated that age, tumor size, grade, pT stage, pN stage, M stage, carcinoembryonic antigen, perineural invasion, tumor deposits, regional nodes examined, and chemotherapy were correlated with OS and CSS. Marital status was independently related to OS. In the development and validation cohorts, the C-index of OS was 0.766 and 0.744, respectively, and the C-index of CSS was 0.826 and 0.809, respectively. Calibration curves and ROC curves showed predictive accuracy. DCA showed that the nomograms had excellent potency over the 8th edition of the TNM staging system with higher clinical net benefits. Significant differences in OS and CSS were observed among low-, medium-, and high-risk groups.

CONCLUSIONS

Nomograms were developed for the first time to predict personalized 1-, 3-, and 5-year OS and CSS in CRMA postoperative patients. External and internal validation confirmed the excellent discrimination and calibration ability of the nomograms. The nomograms can help clinicians design personalized treatment strategies and assist with clinical decisions.

Leveraging Comprehensive Cancer Registry Data to Enable a Broad Range of Research, Audit and Patient Support Activities

Simple Summary

Registry data has the potential to support a broad range of research, audit and education initiatives. Here, we describe the experience and learnings of a series of large multi-institutional cancer registries that leverage real-world clinical data for a range of purposes, that informs the conduct and output of each registry in a virtuous cycle. Lessons learnt include the need for careful and continuous curation of information being collected, regular database updates, and the need for a continued focus on data quality. As a standalone resource, each registry has supported numerous projects, but linkage with external datasets with patients in common has enhanced the research potential. Multiple projects have linked registry data with matched tissue specimens to support the discovery and valiation of prognostic and predictive markers in the tumour and blood specimens. Registry-based biomarker trials have been successfully supported, generating novel and practice-changing data. Registry-based clinical trials, particularly studies exploring the best use of drug options are now complementing the research conducted in traditional clinical trials. More recent projects supported by the registries include health economic studies, personalised patient education material, and increased consumer engagement, including consumer entered data.

Abstract

Traditional cancer registries have often been siloed efforts, established by single groups with limited objectives. There is the potential for registry data to support a broad range of research, audit and education initiatives. Here, we describe the establishment of a series of comprehensive cancer registries across the spectrum of common solid cancers. The experience and learnings of each registry team as they develop, implement and then use collected data for a range of purposes, that informs the conduct and output of other registries in a virtuous cycle. Each registry is multi-site, multi-disciplinary and aims to collect data of maximal interest and value to a broad range of enquiry, which would be accessible to any researcher with a high-quality proposal. Lessons learnt include the need for careful and continuous curation of data fields, with regular database updates, and the need for a continued focus on data quality. The registry data as a standalone resource has supported numerous projects, but linkage with external datasets with patients in common has enhanced the audit and research potential. Multiple projects have linked registry data with matched tissue specimens to support prognostic and predictive biomarker studies, both validation and discovery. Registry-based biomarker trials have been successfully supported, generating novel and practice-changing data. Registry-based clinical trials, particularly randomised studies exploring the optimal use of available therapy options are now complementing the research conducted in traditional clinical trials. More recent projects supported by the registries include health economic studies, personalised patient education material, and increased consumer engagement, including consumer entered data.

Immune Response in Colorectal Carcinoma: A Review of Its Significance as a Predictive and Prognostic Biomarker

Colorectal carcinoma is a leading cause of cancer-related death worldwide. There is significant prognostic heterogeneity in stage II and III tumours, necessitating the development of new biomarkers to better identify patients at risk of disease progression. Recently, the tumour immune environment, particularly the type and quantity of T lymphocytes, has been shown to be a useful biomarker in predicting prognosis for patients with colorectal carcinoma. In this review, the significance of the immune response in colorectal carcinoma, including its influence on prognosis and response to therapy, will be detailed.

Beyond standard data collection – the promise and potential of BRAIN (Brain tumour Registry Australia INnovation and translation registry)

Background

Real-world data (RWD) is increasingly being embraced as an invaluable source of information to address clinical and policy-relevant questions that are unlikely to ever be answered by clinical trials. However, the largely unrealised potential of RWD is the value to be gained by supporting prospective studies and translational research. Here we describe the design and implementation of an Australian brain cancer registry, BRAIN, which is pursuing these opportunities.

Methods

BRAIN was designed by a panel of clinicians in conjunction with BIOGRID to capture comprehensive clinical data on patients diagnosed with brain tumours from diagnosis through treatment to recurrence or death. Extensive internal and external testing was undertaken, followed by implementation at multiple sites across Victoria and Tasmania.

Results

Between February 2021 and December 2021, a total of 350 new patients from 10 sites, including one private and two regional, were entered into BRAIN. Additionally, BRAIN supports the world’s first registry trial in neuro-oncology, EX-TEM, addressing the optimal duration of post-radiation temozolomide; and BioBRAIN, a dedicated brain tumour translational program providing a pipeline for biospecimen collection matched with linked clinical data.

Conclusions

Here we report on the first data collection effort in brain tumours for Australia, which we believe to be unique worldwide given the number of sites and patients involved and the extent to which the registry resource is being leveraged to support clinical and translational research. Further directions such as passive data flow and data linkages, use of artificial intelligence and inclusion of patient-entered data are being explored.

Comparison of Immune Response Assessment in Colon Cancer by Immunoscore (Automated Digital Pathology) and Pathologist Visual Scoring

Simple Summary

The immune response to colon cancer (CC) is highly variable among patients and is clinically relevant. In this study, we compared the immune response assessment for early-stage CC, as measured by Immunoscore (IS), to pathologist visual scoring of the CD3+ and CD8+ T-cell densities at the tumor site (T-score). The objectives were to determine the inter-observer agreement between pathologists and the concordance between the two methods. Agreement between pathologists was minimal to weak. Moreover, a weak concordance between the two methods was observed, leading to misclassification of 48% of cases by pathologist scoring. Due to the high level of immune infiltrate heterogeneity resulting in disagreement of interpretation among pathologists, IS is unlikely to be reproduced via non-standardized methods.

Abstract

Adjunction of immune response into the TNM classification system improves the prediction of colon cancer (CC) prognosis. However, immune response measurements have not been used as robust biomarkers of pathology in clinical practice until the introduction of Immunoscore (IS), a standardized assay based on automated artificial intelligence assisted digital pathology. The strong prognostic impact of the immune response, as assessed by IS, has been widely validated and IS can help to refine treatment decision making in early CC. In this study, we compared pathologist visual scoring to IS. Four pathologists evaluated tumor specimens from 50 early-stage CC patients and classified the CD3+ and CD8+ T-cell densities at the tumor site (T-score) into 2 (High/Low) categories. Individual and overall pathologist scoring of immune response (before and after training for immune response assessment) were compared to the reference IS (High/Low). Pathologists’ disagreement with the reference IS was observed in almost half of the cases (48%) and training only slightly improved the accuracy of pathologists’ classification. Agreement among pathologists was minimal with a Kappa of 0.34 and 0.57 before and after training, respectively. The standardized IS assay outperformed expert pathologist assessment in the clinical setting.

Clinical Features, Molecular Alterations and Prognosis of Colorectal Adenocarcinoma With Mucinous Component in Chinese Patients

Mucinous adenocarcinoma (MAC) is conventionally diagnosed by WHO definition when the extracellular mucin is >50% of the tumor area, while tumors with <50% mucin are designated as having a mucinous component. The study is aimed at analyzing the clinicopathologic characteristics, mutation spectrum, and prognosis of colorectal adenocarcinoma with mucinous component (CAWMC). Mutation analyses for exon 2 to 4 of KRAS gene and exon 15 of BRAF gene were performed by Sanger sequencing. Expression of DNA mismatch repairs and P53 proteins were evaluated by immunohistochemistry. Density of tumor-infiltrating lymphocyte (TIL) status was scored. We also evaluated the percentage of glands producing mucin and the morphology of the different tumor cell types in mucin pools. We retrospectively analyzed the prognosis of 43 patients with stage II/III. The overall frequencies of KRAS and BRAF mutations were 36% and 8%, respectively. Patients with MAC exhibiting high levels of mucin were related to the increase of tumor diameter (P=0.038) but were not associated with any of the other clinicopathologic parameters. The proportion or variable morphology of mucinous component did not stratify progression-free survival in stage II/III cases. TIL was the most significant predictor of progression-free survival among stage II/III CAWMC. It is interesting to note that signet ring cell carcinoma does not portend a worse prognosis for patients with high TIL levels. Combining use the grade of TIL status with the WHO grade of the entire tumor can help identify patients with a high risk of recurrence more accurately.

Risk Factors for Recurrence of Radically Resected Mucinous Colorectal Adenocarcinoma

Background

Mucinous adenocarcinoma (MA) is a subtype of colorectal cancer (CRC) associated with a higher incidence of local extension and worse survival compared to non-mucinous adenocarcinoma, but few studies have investigated surgery-related predictors for recurrence of MA. Therefore, we aimed to elucidate the predictors for local recurrence and remote metastasis of MA after surgery.

Patients and Methods

This study retrospectively analyzed 162 patients with mucinous colorectal adenocarcinoma (MAC) after radical resection. Analysis variables included demographics, clinical indicators, pathologic stage, surgical procedure, adjuvant therapy, and recurrence. Univariate and multivariate analyses were performed to investigate the risk factors for local and distant tumor relapse.

Results

A total of 162 patients (86 male) with a mean age of 58.26 years were included; 70.37% of patients had colonic tumors, and 29.63% had rectal tumors. The 5-year disease-free survival (DFS) rates for these patients were as follows: 100% for TNM stage I, 71.2% for stage II, and 47.8% for stage III. Five-year DFS rates of MAC, colonic and rectal MA were 62.0%, 65.8%, and 51.7%, respectively. Local recurrence occurred in 38 patients and distant metastasis in 33 patients. In univariate analysis, predictors for local recurrence of MAC were intraoperative blood loss, intraoperative transfusion, and N2 stage; and predictors for distant metastasis were male sex, CA199, CEA, intraoperative blood loss, T4 stage, and N2 stage. In multivariate analysis, predictors for local recurrence of MAC were intraoperative transfusion (P=0.04, OR=4.175) and N2 stage (P=0.000, OR=5.291), and predictors for distant metastasis were male sex (P=0.049, OR=2.410), CA199 (P=0.02, OR=1.003), and T4 stage (P=0.007, OR=4.006).

Conclusion

Intraoperative transfusion and N2 stage were significant predictors for local recurrence. Male sex, CA199, and T4 stage were significant predictors for distant metastasis. Knowledge of the risk factors for postoperative recurrence provides a basis for logical approaches to treatment and follow-up of MAC.

Molecular profiling of the intestinal mucosa and immune cells of the colon by multi-parametric histological techniques

The impact of the post-mortem interval (PMI) on the optical molecular characteristics of the colonic mucosa and the gut-associated lymphoid tissue (GALT) were examined by multi-parametric measurements techniques. Inflammatory cells were identified by immunohistochemical staining. Molecular parameters were estimated using the Raman spectroscopy (RS) and Fourier Transform Infrared (FTIR) spectroscopic imaging. The 3D refractive index (3D-RI) distributions of samples were determined using the digital holographic tomography. The distribution of immune cells between post-mortem (PM) and normal controls did show significant differences for CD4 (P = 0.0016) or CD8 (P < 0.0001), whose expression level was decreased in PM cases. No association was found between individual PMI values and inflammatory cell distribution. However, there was a tendency for a negative correlation between CD4⁺ cells and PMI (r = - 0.542, P = 0.032). The alterations ongoing in post-mortem tissue may suggest that PMI has a suppressive effect on the effector properties of the cell-mediated immunity. Moreover, it was confirmed that spectroscopic and digital holotomographic histology are also a useful technique for characterization of the differences in inflammation of varying intensity and in GALT imaging in a solid tissue. Anatomical location of immune cells and methods of tissue fixation determine the molecular and optical parameters of the examined cases.

Clinical significance of a microRNA signature for the identification and predicting prognosis in colorectal cancers with mucinous differentiation

Accumulating evidence supports the fact that the mere presence of mucinous differentiation in colorectal cancer (CRC), rather than its proportion, is a more accurate representative of a particular CRC subtype with distinct clinical and molecular features. In addition, the prognostic significance of the mucinous carcinoma (MC) subtype remains poorly understood and biomarkers have been barely explored in this disease. Herein, we have performed a systematic and comprehensive analysis in MCs and non-MCs and identified a panel of microRNAs (miRNAs) that are differentially expressed between these two subtypes of CRC. Next, we interrogated their clinical significance and demonstrated their robust diagnostic and prognostic clinical ability in CRCs with mucinous differentiation. Finally, we established an integrative risk-assessment model by combining the miRNA-based risk scores together with TNM staging, which was a superior predictor of prognosis in mucinous CRC patients. Collectively, we report a novel miRNA biomarker panel for the identification and predicting survival in CRC patients with mucinous differentiation.

CMTM6 expression in M2 macrophages is a potential predictor of PD-1/PD-L1 inhibitor response in colorectal cancer

Background

CMTM6 is a novel key regulator of PD-L1. High expression of both CMTM6 and PD-L1 may predict the benefit of PD-1 axis blockade in lung cancer. We aimed to investigate the expression pattern of CMTM6 between mismatch repair-defective (dMMR) and mismatch repair-proficient (pMMR) colorectal cancer (CRC) tissues and assess its correlation with the response to PD-1/PD-L1 pathway blockade.

Methods

Immunohistochemistry (IHC) was used to analyze CMTM6 and PD-L1 expression and immune cell density in dMMR/pMMR CRC. Quantitative multiplex immunofluorescence (IF) was performed to detect CMTM6, PD-L1, CD4, CD8, CD68 and CD163 expression in CRC patients treated with PD-1/PD-L1 inhibitors.

Result

IHC analysis showed that CMTM6 and PD-L1 were both expressed in tumor cells (TCs) and invasion front immune cells (ICs). CMTM6 and PD-L1 expression and CD4⁺, CD8⁺, CD68⁺ or CD163⁺ cell density were significantly higher in dMMR CRC patients than in pMMR CRC patients. CMTM6 expression was positively correlated with PD-L1 expression and CD163⁺ M2 macrophage density in dMMR CRC. IF analysis showed that the coexpression rate of CMTM6/PD-L1 and the expression rate of CMTM6 in CD8⁺ T cells and CD163⁺ M2 macrophages were significantly increased in the group that exhibited clinical benefit. CMTM6 expression in M2 macrophages was identified as the best biomarker for predicting the responsiveness to PD-1/PD-L1 inhibitors.

Conclusions

CMTM6 expression in M2 macrophages may predict the PD-1/PD-L1 inhibitor response rate in CRC patients more accurately than dMMR/microsatellite instability-high (MSI-H) status. It can also identify pMMR CRC patients who could benefit from PD-1/PD-L1 inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-02931-6.

Synaptophysin expression in V600EBRAF-mutated advanced colorectal cancers identifies a new subgroup of tumours with worse prognosis

BACKGROUND

Neuroendocrine differentiation has been extensively associated with worse prognosis and to mechanisms of therapy resistance in several epithelial cancers. A high prevalence of neuroendocrine differentiation was recently described in ^V600EBRAF-mutated (BRAFmt) metastatic colorectal cancers (mCRCs) but no data are available about its prognostic impact in this setting.

METHODS

We assessed synaptophysin immunohistochemical expression in a multi-institutional series of 159 BRAFmt mCRCs with matched clinical and pathological information. Tumours were dichotomized as synaptophysin high and low. Overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan-Meier and log-rank tests.

RESULTS

Thirty-five tumours (22.0%) showed any level of positivity for synaptophysin, and 18 (11.3%) were characterized by positivity in at least 20% of tumour cells. Four cases resulted 100% synaptophysin positive. The histotype of synaptophysin-positive tumours (i.e. ≥20%) was not otherwise specified in 11 cases (61.1%) and mucinous adenocarcinoma in 4 cases (22.2%). Four cases were DNA mismatch repair deficient (22.2%) and 7 (38.9%) were characterized by a high number of tumour-infiltrating lymphocytes. At multivariate analysis, high synaptophysin expression was a negative independent prognostic factor for both PFS (HR = 2.00, 95% confidence interval [CI] 1.21-3.33, p = 0.006) and OS (HR = 2.27, 95% CI 1.35-3.85, p = 0.001).

CONCLUSIONS

Among BRAFmt mCRCs, synaptophysin-positive tumours are characterized by worse PFS and OS. Further studies should investigate the molecular mechanisms involved in the acquisition of the neuroendocrine phenotype to identify novel-targeted treatment strategies.

Development and validation of MMR prediction model based on simplified clinicopathological features and serum tumour markers

BACKGROUND

Although simplified clinicopathological features and serum tumour markers (STMs) were reported to be associated with the status of mismatch repair (MMR) in colorectal cancer (CRC) patients, their predictive value alone or in combination for MMR status remains unknown.

METHODS

A retrospective analysis of 3274 participants with MMR testing and STMs measurements from two institutions was conducted. The prediction model was developed in the primary cohort that consisted of 1964 participants. Best subset regression was applied to select the most useful predictors from the primary dataset. The performance of the nomogram was evaluated with respect to its calibration, discrimination, and clinical usefulness. External validation was performed in an independent validation cohort of 1310 consecutive CRC patients.

FINDINGS

Among the ten simplified clinicopathological features, seven variables were selected as the best subset of risk factors to develop pathology-based model, including age, tumour diameters, histology, tumour location, perineural invasion, the number of sampled lymph nodes (LNs) and positive LNs. The model showed good calibration and discrimination, with an AUC of 0.756 (95% CI, 0.722 to 0.789) in the primary cohort and 0.754 (95% CI, 0.715 to 0.793) in the validation cohort. After the addition of CEA and CA 72-4, the performance of pathology-based model was significantly improved in in both the primary cohort (AUC: 0.805 (0.774-0.835) vs. 0.756 (0.722-0.789), P < 0.001) and validation cohort (AUC: 0.796 (0.758-0.835) vs. 0.754 (0.715-0.793), P < 0.001). The results of decision curve analysis revealed that using our models to predict the status of MMR would add more benefit than either the detect-all-patients scheme or the detect-none scheme.

INTERPRETATION

The models based on simplified clinicopathological features alone or in combination with STMs can be conveniently used to facilitate the postoperative individualized prediction of MMR status in CRC patients.

Immuno-Interface Score to Predict Outcome in Colorectal Cancer Independent of Microsatellite Instability Status

Simple Summary

For pathologists, how to precisely diagnose cancer from microscopy slides of tumor tissue samples so that each patient may receive the optimal treatment for his specific type of disease is a major task. Recent research based on digital pathology image analysis enables new approaches to assess tumor-host interaction at a microscopic level. The current study applies a novel spatial analysis method which computes Immunogradient indicators to estimate the migration of immune cells towards the tumor across the tumor/stroma interface. These indicators, computed for two types of immune cells (CD8 and CD20), proved to be independent prognostic factors in this study of 87 patients with colorectal cancer. The indicators were combined with infiltrative tumor growth pattern, assessed by a pathologist, into a new immuno-interface score which enabled prediction of the patient survival independent of other clinical, pathology and molecular characteristics of the tumor. The study demonstrates the value of computational pathology to advance the precision of clinical decision-making.

Abstract

Tumor-associated immune cells have been shown to predict patient outcome in colorectal (CRC) and other cancers. Spatial digital image analysis-based cell quantification increases the informative power delivered by tumor microenvironment features and leads to new prognostic scoring systems. In this study we evaluated the intratumoral density of immunohistochemically stained CD8, CD20 and CD68 cells in 87 cases of CRC (48 were microsatellite stable, MSS, and 39 had microsatellite instability, MSI) in both the intratumoral tumor tissue and within the tumor-stroma interface zone (IZ) which was extracted by a previously developed unbiased hexagonal grid analytics method. Indicators of immune-cell gradients across the extracted IZ were computed and explored along with absolute cell densities, clinicopathological and molecular data, including gene mutation (BRAF, KRAS, PIK3CA) and MSI status. Multiple regression modeling identified (p < 0.0001) three independent prognostic factors: CD8+ and CD20+ Immunogradient indicators, that reflect cell migration towards the tumor, were associated with improved patient survival, while the infiltrative tumor growth pattern was linked to worse patient outcome. These features were combined into CD8-CD20 Immunogradient and immuno-interface scores which outperformed both tumor-node-metastasis (TNM) staging and molecular characteristics, and importantly, revealed high prognostic value both in MSS and MSI CRCs.

Study and analysis of antitumor resistance mechanism of PD1/PD-L1 immune checkpoint blocker

Immunocheckpoint proteins of tumor infiltrating lymphocytes play an important role in tumor prognosis in the course of tumor clinicopathology. PD‐1 (Programmed cell death protein 1) is an important immunosuppressive molecule. By binding to PD‐L1 (programmed cell death‐ligand 1), it blocks TCR and its costimulus signal transduction, inhibits the activation and proliferation of T cells, depletes the function of effector T cells, and enables tumor cells to achieve immune escape. In recent years, immunocheckpoint blocking therapy targeting the PD‐1/PD‐L1 axis has achieved good results in a variety of malignant tumors, pushing tumor immunotherapy to a new milestone, such as anti‐PD‐1 monoclonal antibody Nivolumab, Pembrolizumab, and anti‐PD‐L1 monoclonal antibody Atezolizumab, which are considered as potential antitumor drugs. It was found in clinical use that some patients obtained long‐term efficacy, but most of them developed drug resistance recurrence in the later stage. The high incidence of drug resistance (including primary and acquired drug resistance) still cannot be ignored, which limited its clinical application and became a new problem in this field. Due to tumor heterogeneity, current limited research shows that PD‐1 or PD‐L1 monoclonal antibody drug resistance may be related to the following factors: mutation of tumor antigen and antigen presentation process, multiple immune checkpoint interactions, immune microenvironment changes dynamically, activation of oncogenic pathways, gene mutation and epigenetic changes of key proteins in tumors, tumor competitive metabolism, and accumulation of metabolites, etc, mechanisms of resistance are complex. Therefore, it is the most urgent task to further elucidate the mechanism of immune checkpoint inhibitor resistance, discover multitumor universal biomarkers, and develop new target agents to improve the response rate of immunotherapy in patients. In this study, the mechanism of anti‐PD‐1/PD‐L1 drug resistance in tumors, the potential biomarkers for predicting PD‐1 acquired resistance, and the recent development of combination therapy were reviewed one by one. It is believed that, based on the complex mechanism of drug resistance, it is of no clinical significance to simply search for and regulate drug resistance targets, and it may even produce drug resistance again soon. It is speculated that according to the possible tumor characteristics, three types of treatment methods should be combined to change the tumor microenvironment ecology and eliminate various heterogeneous tumor subsets, so as to reduce tumor drug resistance and improve long‐term clinical efficacy.