Patterns and prognostic relevance of PD-1 and PD-L1 expression in colorectal carcinoma

The density of Tbet+ tumor-infiltrating T lymphocytes reflects an effective and druggable preexisting adaptive antitumor immune response in colorectal cancer, irrespective of the microsatellite status

Purpose: The recent success of anti-PD1 antibody in metastatic colorectal cancer (CRC) patients with microsatellite instability (MSI), known to be associated with an upregulated Th1/Tc1 gene signature, provides new promising therapeutic strategies. However, the partial objective response highlights a crucial need for relevant, easily evaluable, predictive biomarkers. Here we explore whether in situ assessment of Tbet+ tumor infiltrating lymphocytes (TILs) reflects a pre-existing functional antitumor Th1/Tc1/IFNγ response, in relation with clinicopathological features, microsatellite status and expression of immunoregulatory molecules (PD1, PDL1, IDO-1).

Methodology: In two independent cohorts of CRC (retrospective n = 80; prospective n = 27) we assessed TILs density (CD3, Tbet, PD1) and expression profile of PDL1 and IDO-1 by immunohistochemistry/image analysis. Furthermore, the prospective cohort allowed to perform ex vivo CRC explant cultures and measure by Elisa the IFNγ response, at baseline and upon anti-PD1 treatment.

Results: The density of Tbet+ TILs was significantly higher in MSI CRC, especially in the medullary subtype but also in a subgroup of MSS (microsatellite stable), and positively correlated with PD1 and PDL1 expression, but not with IDO-1. Finally, a high number of Tbet+ TILs was associated with a favorable overall survival. These Tbet+ TILs were functional as their density positively correlated with basal IFNγ levels. In addition, the combined score of Tbet+ PD1+ TILs coupled with IDO-1 expression predicted the magnitude of the IFNγ response upon anti-PD1.

Conclusion: Altogether, immunohistochemical quantification of Tbet+ TILs is a reliable and accurate tool to recapitulate a preexisting Th1/Tc1/IFNγ antitumor response that can be reinvigorated by anti-PD1 treatment.

Chimeric tumor modeling reveals role of partial PDL1 expression in resistance to virally induced immunotherapy

Expression of PDL1 on the surface of tumor cells can blunt the efficacy of many cancer immunotherapies. For example, our lab has previously shown that tumors derived from malignant cells incapable of expressing PDL1 are highly susceptible to immunotherapy induced by oncolytic virus treatment while tumors derived from PDL1 capable cells are highly resistant. In patient biopsies, however, expression of PDL1 on malignant cells is often not uniform with some cells expressing PDL1 while others do not. Importantly, how this partial PDL1 positivity influences the outcomes of immunotherapy remains largely unknown. In the current work, we expand on our previous findings by generating partially PDL1 positive tumors in immune competent animals and asking what percentage of tumor cells must express PDL1 for a tumor to become functionally resistant to oncolytic treatment. Our results indicate that the responsiveness of partially PDL1⁺ tumors correlates linearly with the percentage of PDL1 capable cells present at the initiation of treatment. Additionally, we observe that tumors which relapse after treatment display a significant increase in the numbers of PDL1 capable cells present suggesting that specific editing of mixed tumors might play a role in disease relapse. These data indicate that varying levels of PDL1 expression can play a significant role in the outcomes of oncolytic immunotherapy and challenges the concept that tumors should be viewed as simply PDL1⁺ or PDL1⁻.

Cellular localization of PD-L1 expression in mismatch-repair-deficient and proficient colorectal carcinomas

Blockade of the interaction between PD-1 and its ligands PD-L1 has shown clinical efficacy across several tumor types, especially in mismatch-repair-deficient colorectal carcinoma. The aim of this study was to examine the pattern and cellular localization of PD-L1 expression in the different molecular subtypes of mismatch-repair-deficient colorectal cancers vs. their mismatch-repair-proficient counterparts. PD-L1/SATB2 double-antibody-immunohistochemistry was utilized to distinguish tumor cell from immune cell staining. We observed in our series of 129 colorectal adenocarcinomas that PD-L1 expression occurred primarily in tumor-associated-immune cells and most prominently at the tumor-stroma-interface of the invasive front. The level of invasive front immune cell staining was significantly higher in mismatch-repair-deficient tumors compared to mismatch-repair-proficient tumors (p < 0.001), but no difference was observed among the different subtypes of mismatch-repair-deficient tumors: Lynch syndrome-associated vs. MLH1-methylated vs. unexplained. While selected mismatch-repair-proficient tumors exhibited unusually high tumor-infiltrating-lymphocytes and had high level immune cell PD-L1 expression, a positive correlation between PD-L1 expression and high lymphocyte count was detected only in mismatch-repair-deficient tumors (r = 0.39, p < 0.001) and not in mismatch-repair-proficient tumors. Notably, true tumor cell PD-L1 expression in colorectal carcinoma was rare, present in only 3 of 129 tumors (2.3%): 2 MLH1-methylated and 1 mismatch-repair-proficient with high tumor-infiltrating-lymphocytes; and the staining in the tumor cells in all 3 was diffuse (>=50% of the tumor). These findings may serve to inform further efforts aiming to evaluate PD-L1 immunohistochemistry vis-à-vis molecular sub-classification as predictive biomarkers in the treatment of colorectal carcinoma.

Neuroendocrine Differentiation, Microsatellite Instability, and Tumor-infiltrating Lymphocytes in Advanced Colorectal Cancer With BRAF Mutation

BACKGROUND

Approximately 10% of metastatic colorectal cancer (mCRC) cases will harbor the BRAF p.V600E mutation (BRAF-mCRC) and have been associated with a poor prognosis. Although they are usually considered a unique clinical entity, biologic heterogeneity has been described. We performed an extensive clinicopathologic study of a multicenter series of BRAF-mCRC to highlight differences between tumors with microsatellite instability (MSI) and microsatellite stable tumors, focusing on both inflammatory profiles and neuroendocrine differentiation.

METHODS

We included 59 BRAF-mCRC cases and collected the clinical data (ie, surgery, treatment, and follow-up). We evaluated MSI status, budding, lympho-angioinvasion, neuroinvasion, extent of active stroma, CD3⁺ and CD8⁺ intratumoral and peritumoral lymphocytes, programmed cell death ligand 1, p53, Ki-67, synaptophysin, and CDX2 expression.

RESULTS

The 22 MSI BRAF-mCRC cases were associated with the right side (P < .0001), an expansive grown pattern (P < .01), programmed cell death ligand 1 expression (P < .0001), high CD8 T-cell content (P = .0001), and lymph node metastases (P < .029). The 37 MSS BRAF-mCRC cases were characterized by a greater stromal component (P = .0002), pulmonary metastases (P = .095), and p53 and synaptophysin immunoreactivity (P = .004 and P = .001, respectively). Univariate analysis demonstrated that MSI and a high CD8 T-cell content were associated with a 34% (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.34-1.28; P = .2) and 33% (HR, 0.67; 95% CI, 0.45-0.99; P = .04) reduction in the risk of death, respectively. The combined presence of MSI and CD8 T-cell content decreased the hazard of mortality ≤ 63% (HR, 0.37; 95% CI, 0.14-0.97; P = .2), which was slightly reduced after multivariate analysis.

CONCLUSION

A simultaneous evaluation of MSI, CD8 T-cell content, and neuroendocrine markers could allow for the identification of subsets of BRAF-mCRC with a different prognosis and potential eligibility for specific treatments.

The Immunoscore is a Superior Prognostic Tool in Stages II and III Colorectal Cancer and is Significantly Correlated with Programmed Death-Ligand 1 (PD-L1) Expression on Tumor-Infiltrating Mononuclear Cells

BACKGROUND

In colorectal cancer (CRC), the indication for immune checkpoint inhibitors is determined by the microsatellite instability status of the tumors. However, an optimal biomarker for their indication has not been fully identified to date. This study aimed to establish the clinicopathologic importance of the Immunoscore (IS) in CRC and to clarify the relationships between the IS, programmed death-ligand 1 (PD-L1) expression, and tumor-associated macrophages.

METHODS

In 132 cases, CRC was diagnosed and surgically treated in our department from 2009 to 2010. Immunohistochemical staining using primary antibodies PD-L1, CD3, CD8, CD68, and CD163 was performed. The IS was determined according to the proposal of an international task force. Statistical analyses were performed to investigate the correlation between the IS, clinicopathologic variables, and expression of immune checkpoint molecules.

RESULTS

The overall survival (OS) and relapse-free survival (RFS) in the high-IS group (I3-4) were significantly better than in the low-IS group (I0-2) (OS: P = 0.0420; RFS: P = 0.0226). The positivity rate for PD-L1 on tumor cells (tPD-L1) was only 0.8%, whereas that for PD-L1 on interstitial tumor-infiltrating mononuclear cells (iPD-L1) was 18.2%. The iPD-L1-positive group showed significantly better survival in terms of both OS and RFS than the iPD-L1-negative group (OS: P = 0.0278; RFS: P = 0.0253). The findings showed significant correlation between the IS and iPD-L1 expression (P < 0.0001).

CONCLUSIONS

The study found that a high IS was a good indicator of a better prognosis and significantly correlated with iPD-L1 expression in CRC.

Pathological and Molecular Characteristics of Colorectal Cancer with Brain Metastases

Background: Colorectal cancers (CRC) with brain metastases (BM) are scarcely described. The main objective of this study was to determine the molecular profile of CRC with BM. Methods: We included 82 CRC patients with BM. KRAS, NRAS, BRAF and mismatch repair (MMR) status were investigated on primary tumors (n = 82) and BM (n = 38). ALK, ROS1, cMET, HER-2, PD-1, PD-L1, CD3 and CD8 status were evaluated by immunohistochemistry, and when recommended, by fluorescence in situ hybridization. Results: In primary tumors, KRAS, NRAS and BRAF mutations were observed in 56%, 6%, and 6% of cases, respectively. No ROS1, ALK and cMET rearrangement was detected. Only one tumor presented HER-2 amplification. Molecular profiles were mostly concordant between BM and paired primary tumors, except for 9% of discordances for RAS mutation. CD3, CD8, PD-1 and PD-L1 expressions presented some discordance between primary tumors and BM. In multivariate analysis, multiple BM, lung metastases and PD-L1+ tumor were predictive of poor overall survival. Conclusions: CRCs with BM are associated with high frequency of RAS mutations and significant discordance for RAS mutational status between BM and paired primary tumors. Multiple BM, lung metastases and PD-L1+ have been identified as prognostic factors and can guide therapeutic decisions for CRC patients with BM.

Emerging Role of Immune Checkpoint Blockade in Pancreatic Cancer

Immune checkpoint blockade (ICB) with programmed cell death protein-1(PD-1)/programmed death ligand -1(PD-L1) antibodies has revolutionized the management of several cancers, especially non-small cell lung cancer, melanoma, urothelial, and renal cancer. Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers associated with high morbidity and mortality. Based on available data, it's obvious that ICB has limited success in PDACs, which can be explained by the low immunogenicity and immunosuppressive tumor microenvironment of these tumors. In this review article, we focus on PD-L1 expression and microsatellite instability (MSI) in PDAC, and their roles as prognostic and predictive markers. We also discuss data supporting combination therapies to augment cancer immunity cycle. Combining anti-PD-1/PD-L1 agents with other modalities such as vaccines, chemotherapy, and radiation could potentially overcome resistance patterns and increase immune responsiveness in PDAC.

The clinicopathological and prognostic value of programmed death-ligand 1 in colorectal cancer: a meta-analysis

INTRODUCTION

Programmed death-ligand 1 (PD-L1) is reportedly expressed in colorectal tumors. However, the prognostic role of PD-L1 in colorectal cancer (CRC) remains controversial. Therefore, we performed a meta-analysis to investigate the clinicopathological and prognostic impact of PD-L1 in CRC.

METHODS

A comprehensive search in PubMed, Embase, the Cochrane Library, Web of Science and the ClinicalTrials.gov for publications about PD-L1 expression in colorectal cancer was done. The correlation between PD-L1 expression and clinicopathological features or survival outcomes was analyzed by odds ratios (OR) or hazard ratios (HR), at 95% confidence intervals (CI).

RESULTS

The results show that the pooled HR of (1.34, 95% CI 1.02-1.65, p = 0.01) indicated the association of PD-L1 expression with overall survival (OS) in CRC patients. Meanwhile, the expression of PD-L1 was positively correlated with the lymph node metastasis (OR: 0.70, 95% CI 0.51-0.95, p = 0.00), gender (OR: 0.86, 95% CI 0.76-0.98, p = 0.05) and tumor location (OR: 1.39, 95% CI 1.14-1.71, p = 0.12).

CONCLUSIONS

These results suggest that high expression of PD-L1 is associated with low OS in CRC. High PD-L1 expression may act as a negative factor for patients with CRC and help to identify patients suitable for anticancer therapy.

Clinical significance of programmed death 1 ligand-1 (CD274/PD-L1) and intra-tumoral CD8+ T-cell infiltration in stage II-III colorectal cancer

Programmed cell death-1 (PDCD1/PD-1) and its ligand programmed cell death 1 ligand 1 (CD274/PD-L1) have been reported to suppress anti-tumor T cell-mediated immune responses. However, the clinical significance of CD274 in colorectal cancer were still elusive. We aim to clarify the relationships between CD8+ intratumor-infiltrating lymphocytes (TILs) and CD274 as well as their prognostic values in stage II-III colon carcinoma. Tumor differentiation, perineural invasion (PNI), pN stage and DNA mismatch repair (MMR)-deficient were clearly correlated with CD8+ TILs counts within the tumor microenvironment (p < 0.0001). Furthermore, tumor differentiation and PNI were suggestively correlated with tumor CD274 expression (p = 0.02 and p = 0.0195). Tumor CD274 level was significantly correlated with higher CD8+ TILs (p < 0.0001) but was not associated with MMR-deficient status (p = 0.14). High tumor CD274 expression [hazard ratio (HR) = 2.16, 95% CI = 1.63-2.86, p < 0.0001] and CD8+ TILs [HR = 1.51, 95% CI = 1.19-1.91, p = 0.0007] were associated with improved disease-free survival and overall survival. Additionally, the subgroup of patients who had a high CD8+ TILs/tumor CD274 have better survival outcomes compared with other subgroups (71% vs 53%; p < 0.0001). Therefore, the CD8+ TILs counts and tumor CD274 may be prognostic factors to predict survival and therapeutic responses in stage II-III colon carcinoma patients.

The Clinical and Biomarker Association of Programmed Death Ligand 1 and its Spatial Heterogeneous Expression in Colorectal Cancer

Background: Programmed death ligand 1 (PD-L1) expression has been shown to predict benefit from anti-PD-1 treatment in several cancers. However, its predictive value in colorectal cancer seems limited. This study was aimed to explore the clinical and biomarker association of programmed death ligand 1 and its spatial heterogeneous expression in colorectal cancer.

Methods: Tissue microarrays of 422 primary colorectal cancers from our hospital were used for the interpretation of PD-L1 and programmed death 1 (PD-1) expression, cluster of differentiation 4 (CD4) and CD8 density and microsatellite instability (MSI) status by immunohistochemistry. To assess the spatial heterogeneity of PD-L1 expression, Tissue microarrays of 383 paired intra-primary-tumor tissues, and 105 paired lymph node metastatic tumors and 64 paired distant metastatic tumors were also used.

Results: PD-L1 was positive in 188 (44.5%) primary colorectal cancers. PD-L1 expression was associated with less advanced N category (P<0.001), less advanced TNM stage (P<0.001) and less nervous invasion (P=0.04). Higher PD-L1 expression was associated with higher PD-1 expression (P<0.001), higher CD4 (P<0.001) and CD8 (P<0.001) density and DNA mismatch repair deficiency (P=0.01). PD-L1 expression was associated with better disease-free survival and overall survival, but it was only an independent prognostic factor for disease-free survival (hazard ratio and 95% confidence interval: 0.42 [0.25-0.72], P<0.001). The probability of inconsistent PD-L1 expression was respectively 17.8%, 31.4% and 39.1% within primary tumors, between primary tumors and lymph node metastatic tumors, and between primary tumors and distant metastatic tumors. All the three differences were statistically significant (P<0.001, P<0.001 and P=0.05, respectively).

Conclusions: PD-L1 expression was a marker of pre-existing immune responses in colorectal cancer, however, it was heterogeneously expressed in colorectal cancer, especially between primary and metastatic tumors. This might partially explain the low-efficiency of its predictive value for benefit from anti-PD-1 treatment.

Prognostic impact of programmed cell death ligand 1 expression on long-term oncologic outcomes in colorectal cancer

The present study evaluated the association between programmed cell death ligand-1 (PD-L1) expression and long-term oncologic outcomes in colorectal cancer (CRC). PD-L1 expression was evaluated using immunohistochemistry in 175 patients who underwent surgical resection for CRC between September 1999 and August 2004. Patients were grouped according to PD-L1 expression, with 82 (46.9%) and 93 (53.1%) in the low and high PD-L1 expression groups, respectively. The overall survival (OS) and disease-free survival (DFS) rates were significantly better in the high expression group compared with in the low expression group (OS: 48.2 vs. 32.9%, P=0.047; DFS: 43.3 vs. 32.9%, P=0.021). According to the Tumor-Node-Metastasis stage subgroups, the OS rates in the low and high expression groups, respectively, were 66.7 and 60.0% in stage I (P=0.715), 51.8 and 46.7% in stage II (P=0.789), 19.6 and 51.1% in stage III (P=0.011) and 9.1 and 0% in stage IV (P=0.005). The DFS rates in the low and high expression groups, respectively, were 66.7 and 60.0% in stage I (P=0.715), 51.8 and 46.7% in stage II (P=0.857), 19.6 and 38.3% in stage III (P=0.006) and 9.1 and 0% in stage IV (P=0.700). The systemic recurrence rate was significantly higher in the low expression group compared with in the high expression group (42.7 vs. 12.9%, respectively, P=0.030). Low PD-L1 expression was significantly associated with tumor relapse and poor prognosis in stage III CRC.

Immune environment in serrated lesions of the colon: intraepithelial lymphocyte density, PD-1, and PD-L1 expression correlate with serrated neoplasia pathway progression

The serrated neoplasia pathway accounts for approximately 20% of colorectal carcinomas (CRCs). Sessile serrated adenomas (SSAs), the main precursor lesion of the serrated pathway, are molecularly driven by MLH1 promoter methylation and microsatellite instability (MSI) in their progression to CRC. MSI-high (MSI-H) lesions are highly immunogenic and associated with a high density of tumor-infiltrating lymphocytes. Our study's aim was to determine how the kinetics of this immune environment relates to SSAs in their progression through low-grade (SSA-LD) to high-grade dysplasia (SSA-HD) and CRC. We analyzed 74 cases (16 CRCs, 14 SSAs-HD, and 44 SSAs-LD). Cases of hyperplastic polyp and SSA without dysplasia were analyzed for comparison. MSI status, intraepithelial lymphocyte (IEL) density, and immune checkpoint expression were assessed by immunohistochemistry for mismatch repair proteins, CD3, and PD-1/PD-L1, respectively. Average IEL density was 12, 18.6, 21.6, and 31 for SSA, SSA-LD, SSA-HD, and CRC, respectively, as opposed to 8.1 in normal colon (P < .0001). Average PD-1/PD-L1 lymphocytic expression was 1.1/1.0, 1.2/2.9, 4.8/6.9, and 12.4/15.2 in SSA, SSA-LD, SSA-HD, and CRC, respectively, compared with 0.5/0 in normal crypts (P < .0001). IEL and PD-1/PD-L1 lymphocytic expression values of MSI-H lesions were 22.6, 27.7, and 36.8, and 3/6.5, 6.2/10.6, and 18.3/17.6 in MSI-H SSA-LD, SSA-HD, and CRCs, respectively (P ranged from .0478 to .3529). PD-L1 epithelial expression was positive in 40% of SSAs, 59.1% of SSAs-LD, 100% of SSAs-HD, and 60% of CRCs (P < .0001). Increased IELs and PD-1/PD-L1 expression correlate with sequential progression of SSAs, through development of cytologic dysplasia, to CRC and MSI-H status.

Programmed cell death ligand-1 protein expression and CD274/PD-L1 gene amplification in colorectal cancer: Implications for prognosis

Programmed cell death ligand-1 (PD-L1) detection assays have not been standardized for patients with colorectal cancer, and the prognostic value of PD-L1 expression is unclear. We compared the PD-L1 expression patterns in colorectal cancer samples using various immunohistochemical assays using 3 primary PD-L1 antibodies (assay 1, MIH1; assay 2, E1L3; and assay 3, 22C3) and investigated the prognostic implication of PD-L1 expression using each. Additionally, PD-L1 gene amplification was evaluated using FISH. The percentage scorings and positivity rates of the 3 assays differed; the degrees of correlation and concordance between assays 2 and 3 were relatively high, whereas assay 1 was an outlier. Multivariate analyses indicated that PD-L1 positivity in tumor cells and its negativity in tumor-infiltrating lymphocytes were independent predictors of poorer overall and disease-free survival in patients with colorectal cancer. PD-L1 gene amplification was found in 2 patients (PD-L1/CEP ratio, 5.60 and 5.84, respectively); both had strong PD-L1 expression according to immunohistochemistry. Overall, our study showed that PD-L1 expression status in tumor and immune cells is an independent prognostic factor in patients with colorectal cancer. Standardizations of both PD-L1 detection using immunohistochemistry and the cut-off for positivity are necessary. Finally, PD-L1 gene amplification was found in a small fraction of samples, suggesting the possibility of an ancillary test for PD-L1 evaluation.

The Effect of Pembrolizumab in Absence of Programmed Death 1 Receptor

Tumor therapy has evolved greatly since the discovery of immunotherapies. New therapies permit targeted approach with less side effects. Immunotherapies target specific components recognized on tumor cells, such as Programmed death-1 (PD-1). Overexpression of PD-1 markers in solid gastrointestinal tumors is a consequence of deficiency in DNA mismatch repair mechanism. Pembrolizumab is an example of immunotherapy targeting PD-1. Pembrolizumab binding of PD-1 helps the immune system recognize tumor cells and initiate destruction cascade. We present a case of a PD-1 negative appendiceal tumor responding to pembrolizumab.

Expression of programmed cell death protein 1 (PD-1) and its ligand PD-L1 in colorectal cancer: Relationship with sidedness and prognosis

Expression of programmed cell death protein 1 (PD-1) and its ligand PD-L1 has been demonstrated to confer a prognostic value in colorectal cancer (CRC), but no studies have investigated whether this association differs according to tumour location. In this study, immunohistochemical expression of PD-1 and PD-L1 was analysed in tissue microarrays with primary tumours from 557 incident CRC cases from a prospective population-based cohort. Univariable and multivariable Cox regression analyses, adjusted for age, sex, TNM stage, differentiation grade and vascular invasion, were applied to determine the impact of biomarker expression on 5-year overall survival (OS), in the entire cohort and in subgroup analysis of right colon, left colon, and rectum. High PD-L1 expression on tumour-infiltrating immune cells was an independent factor of a prolonged OS in the entire cohort (hazard ratio [HR] = 0.49; 95% confidence interval [CI] CI 0.35 – 0.68), and in tumours of the right colon (HR = 0.43; 95% CI 0.25 – 0.74) and the left colon (HR = 0.28; 95% CI 0.13 – 0.61), but not in rectal cancer. Tumour-specific PD-L1-expression was not prognostic, neither in the full cohort nor according to tumour location. High immune cell-specific PD-1 expression was associated with a prolonged OS in the entire cohort and in tumours of the right colon, but not in the left colon or rectum, and only in univariable analysis. In conclusion, these results demonstrate that immune cell-specific PD-L1 and PD-1 expression is prognostic in a site-dependent manner, whereas tumour-specific PD-L1-expression is not prognostic in CRC.

Integrative analysis of exogenous, endogenous, tumour and immune factors for precision medicine

Immunotherapy strategies targeting immune checkpoints such as the CTLA4 and CD274 (programmed cell death 1 ligand 1, PD-L1)/PDCD1 (programmed cell death 1, PD-1) T-cell coreceptor pathways are revolutionising oncology. The approval of pembrolizumab use for solid tumours with high-level microsatellite instability or mismatch repair deficiency by the US Food and Drug Administration highlights promise of precision immuno-oncology. However, despite evidence indicating influences of exogenous and endogenous factors such as diet, nutrients, alcohol, smoking, obesity, lifestyle, environmental exposures and microbiome on tumour-immune interactions, integrative analyses of those factors and immunity lag behind. Immune cell analyses in the tumour microenvironment have not adequately been integrated into large-scale studies. Addressing this gap, the transdisciplinary field of molecular pathological epidemiology (MPE) offers research frameworks to integrate tumour immunology into population health sciences, and link the exposures and germline genetics (eg, HLA genotypes) to tumour and immune characteristics. Multilevel research using bioinformatics, in vivo pathology and omics (genomics, epigenomics, transcriptomics, proteomics and metabolomics) technologies is possible with use of tissue, peripheral blood circulating cells, cell-free plasma, stool, sputum, urine and other body fluids. This immunology-MPE model can synergise with experimental immunology, microbiology and systems biology. GI neoplasms represent exemplary diseases for the immunology-MPE model, given rich microbiota and immune tissues of intestines, and the well-established carcinogenic role of intestinal inflammation. Proof-of-principle studies on colorectal cancer provided insights into immunomodulating effects of aspirin, vitamin D, inflammatory diets and omega-3 polyunsaturated fatty acids. The integrated immunology-MPE model can contribute to better understanding of environment-tumour-immune interactions, and effective immunoprevention and immunotherapy strategies for precision medicine.

Cytolytic Activity Score to Assess Anticancer Immunity in Colorectal Cancer

BACKGROUND

Elevated tumor-infiltrating lymphocytes (TILs) within the tumor microenvironment is a known positive prognostic factor in colorectal cancer (CRC). We hypothesized that since cytotoxic T cells release cytolytic proteins such as perforin (PRF1) and pro-apoptotic granzymes (GZMA) to attack cancer cells, a cytolytic activity score (CYT) would be a useful tool to assess anticancer immunity.

METHODS

Genomic expression data were obtained from 456 patients from The Cancer Genome Atlas (TCGA). CYT was defined by GZMA and PRF1 expression, and CIBERSORT was used to evaluate intratumoral immune cell composition.

RESULTS

High CYT was associated with high microsatellite instability (MSI-H), as well as high levels of activated memory CD4+T cells, gamma-delta T cells, and M1 macrophages. CYT-high CRC patients had improved overall survival (p = 0.019) and disease-free survival (p = 0.016) compared with CYT-low CRC patients, especially in TIL-positive tumors. Multivariate analysis demonstrated that CYT- high associates with improved survival independently after controlling for age, lymphovascular invasion, colonic location, microsatellite instability, and TIL positivity. The levels of immune checkpoint molecules (ICMs)-programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T-lymphocyte-associated protein 4 (CTLA4), lymphocyte-activation gene 3 (LAG3), T cell immunoglobulin and mucin domain 3 (TIM3), and indoleamine 2,3-dioxygenase 1 (IDO1)-correlated significantly with CYT (p < 0.0001); with improved survival in CYT-high and ICM-low patients, and poorer survival in ICM-high patients.

CONCLUSIONS

High CYT within CRC is associated with improved survival, likely due to increased immunity and cytolytic activity of T cells and M1 macrophages. High CYT is also associated with high expression of ICMs; thus, further studies to elucidate the role of CYT as a predictive biomarker of the efficacy of immune checkpoint blockade are warranted.

Intratumoral immune cells expressing PD-1/PD-L1 and their prognostic implications in cancer: a meta-analysis

BACKGROUND

The prognostic value of immune cells expressing programmed cell death 1 (PD-1) and PD-1 ligand 1 (PD-L1) in cancer are controversial, and the potential differential impact of using tissue microarrays and whole tissue sections to assess the positivity of immune cells has not been addressed.

METHODS

The current study included 30 eligible studies with 7251 patients that evaluated the relationship between tumor-infiltrating lymphocytes expressing PD-1/PD-L1 and overall survival and disease-free survival, or progression-free survival. Subgroup analysis was based on the tissue type of cancer and the type of tissue sampling (tissue microarray or whole tissue section).

RESULTS

In the meta-analysis, PD-1-positive and PD-L1-positive tumor-infiltrating lymphocytes had a positive effect on disease-free survival or progression-free survival (hazard ratio [HR] 0.732; 95% confidence interval [CI] 0.565, 0.947; and HR 0.727; 95% CI 0.584, 0.905, respectively). PD-L1-positive tumor-infiltrating lymphocytes had a positive impact on overall survival in studies using tissue microarray (HR 0.586; 95% CI 0.476, 0.721), but had a poor impact when only whole tissue sections were considered (HR 1.558; 95% CI 1.232, 1.969). Lung cancer was associated with good overall survival and disease-free survival (HR 0.639; 95% CI 0.491, 0.831; and HR 0.693; 95% CI 0.538, 0.891, respectively) for PD-1-positive tumor-infiltrating lymphocytes, and colorectal cancer showed favorable disease-free survival (HR 0.471; 95% CI 0.308, 0.722) for PD-L1-positive tumor-infiltrating lymphocytes.

CONCLUSION

Immune cells expressing PD-1 and PD-L1 within tumors are associated with the prognosis. However, the correlation may vary among different tumor types and by the type of tissue sampling used for the assessment.

Expression Patterns, Prognostic Value, and Intratumoral Heterogeneity of PD-L1 and PD-1 in Thymoma and Thymic Carcinoma

INTRODUCTION

Thymic epithelial tumors (TETs) including thymoma and thymic carcinoma are rare tumors with little data available to guide treatment. Immunotherapy with checkpoint blockade has shown promising activity, but data regarding the expression patterns and prognostic implications of programmed death 1 (PD-1) and its ligand (PD-L1) in TETs have yielded conflicting results. Intratumoral heterogeneity of PD-1/L1 expression has been shown in other cancers, but has not been described in the TET literature.

METHODS

We performed a retrospective single-center review of 35 patients with resected TET. PD-1/L1 expression was assessed by immunohistochemistry using PD-1 clone: NAT105 and PD-L1 clone: 22C3. Tumor samples from 35 patients were evaluated including 32 patients with thymoma and 3 patients with thymic carcinoma.

RESULTS

PD-L1 expression was detected in 83% (29 of 35) tumor samples, including 100% (3 of 3) of thymic carcinoma patients and 81% (26 of 32) of thymoma patients. PD-1 expression was detected in 77% (27 of 35), including 33% (1 of 3) of thymic carcinoma patients and 81% (26 of 32) thymoma patients. High PD-1 expression was associated with lower grade tumors. Unlike prior studies, PD-L1 expression was not associated with higher grade tumors or higher stage. Neither PD-L1 nor PD-1 expression was significantly associated with survival. Three patients with thymoma had multiple tumor sections evaluated for expression of PD-1/L1, with differing expression patterns of both PD-L1 and PD-1 observed in two patients.

CONCLUSIONS

This study confirms high expression of PD-L1 and PD-1 in TET and shows for the first time intratumoral heterogeneity of PD-L1 and PD-1 in thymoma patients.

DNA mismatch repair in cancer

Microsatellite instability (MSI) refers to the hypermutator phenotype secondary to frequent polymorphism in short repetitive DNA sequences and single nucleotide substitution, as consequence of DNA mismatch repair (MMR) deficiency. MSI secondary to germline mutation in DNA MMR proteins is the molecular fingerprint of Lynch syndrome (LS), while epigenetic inactivation of these genes is more commonly found in sporadic MSI tumors. MSI occurs at different frequencies across malignancies, although original methods to assess MSI or MMR deficiency have been developed mostly in LS related cancers. Here we will discuss the current methods to detect MSI/MMR deficiency with a focus of new tools which are emerging as highly sensitive detector for MSI across multiple tumor types. Due to high frequencies of non-synonymous mutations, the presence of frameshift-mutated neoantigens, which can trigger a more robust and long-lasting immune response and strong TIL infiltration with tumor eradication, MSI has emerged as an important predictor of sensitivity for immunotherapy-based strategies, as showed by the recent FDA's first histology agnostic-accelerated approval to immune checkpoint inhibitors for refractory, adult and pediatric, MMR deficient (dMMR) or MSI high (MSI-H) tumors. Moreover, it is known that MSI status may predict cancer response/resistance to certain chemotherapies. Here we will describe the complex interplay between the genetic and clinical-pathological features of MSI/dMMR tumors and the cancer immunotherapy, with a focus on the predictive and prognostic role of MMR status for immune checkpoint inhibitors (ICIs) and providing some suggestions on how to conceive better predictive markers for immunotherapy in the next future.

Potential immune priming of the tumor microenvironment with FOLFOX chemotherapy in locally advanced rectal cancer

Strategies to enhance tumor immunogenicity may expand the role of immunotherapy beyond the mismatch repair-deficient subtype. In this pilot study, biopsies were performed at baseline and after four cycles of FOLFOX in eight patients receiving neoadjuvant chemotherapy for stage II/III locally advanced rectal cancer. Immunostaining was performed for T cell subsets (CD3+, CD8+, CD45RO+); macrophages (CD163+); T regulatory cells (FOXP3+); and expression of MHC class I, PD-1 and PD-L1. Changes in cell number or intensity were quantified and correlated with treatment response. Pretreatment patterns of immune infiltrates were mixed and did not correlate with treatment response. Posttreatment increases in T cell infiltrates (CD3+, CD8+ and CD45RO+) and MHC-I expression were observed in five patients. CD163+ cell numbers increased in four patients. FOXP3+ cell numbers increased in two patients, decreased in two other patients and remained unchanged in three patients. PD-1 scores increased in seven patients, and PD-L1 scores increased in four patients. Changes in tumor T cell responses did not correlate with treatment response. Changes in FOXP3+ cells were associated with treatment response in some patients: two patients with increases in FOXP3+ cells had poor responses, whereas the patient with the greatest reduction in FOXP3+ cells had a complete response. The patient with a complete clinical response had a much higher increase in MHC-I expression than other patients. These results suggest that chemotherapy can increase immune activity in the tumor microenvironment and could potentially be utilized to prime immune responses prior to immunomodulatory treatments.

Nonsmall cell lung cancer from HIV-infected patients expressed programmed cell death-ligand 1 with marked inflammatory infiltrates

OBJECTIVE

Immunotherapies targeting the programmed cell death-1 (PD-1)/PD-ligand 1 (PD-L1) checkpoint improved prognosis in lung cancer. PD-1/PD-L1 status, however, has not been investigated in human immunodeficiency virus (HIV)-positive patients. This study assessed PD-L1 status and tumor immune-cell infiltration in nonsmall cell lung cancer (NSCLC) in HIV patients.

METHODS

Consecutive HIV patients treated between 1996 and 2014 were enrolled. PD-L1 tumor expression was assessed using immunohistochemistry with two antibodies (clones 5H1 and E1L3N), and tumor immune-cell infiltration with CD3, CD4, CD8, CD20, CD163, and MPO. PD-L1 expression and immune infiltration results were compared with those of 54 NSCLCs from unknown HIV status patients.

RESULTS

Thirty-four HIV-positive patients were evaluated: predominantly men (88.2%) (median age: 51.1 years) presenting stage IV (38.2%) adenocarcinomas (76.5%). The median blood CD4 count was 480 cells/μL (86-1120) and 64% exhibited undetectable viral load. The PD-L1 score (percentage of positive cells × intensity) was higher in HIV-positive than HIV-undetermined patients with the E1L3N clone [median (range) 0 (0-150) versus 0 (0-26.7), P = 0.047], yet not with the 5H1 clone [0 (0-120) versus 0 (0-26.7) P = 0.07, respectively]. PD-L1 expression frequency did not differ between both cohorts (18.7 versus 9.3% using E1L3N and 10 versus 5.6% using 5H1 clone, respectively). There were significantly greater cytotoxic T-cell (P < 0.001), B-lymphocyte (P = 0.005), and activated macrophage (P < 0.001) infiltrations in the HIV-positive patients, but no differences for CD4 T cells.

CONCLUSION

Tumors in HIV-positive patients seem to express higher PD-L1 levels with increased immune infiltration, supporting their inclusion in clinical trials assessing immune checkpoint inhibitors.

PD-L1 expression in colorectal cancer defines three subsets of tumor immune microenvironments

Objectives

We investigated the PD-L1 expression in colorectal cancer (CRC) and in its microenvironment.

Results

PD-L1 was expressed in neoplastic cells (NCs) and tumor-infiltrating immune cells (IICs). All samples PD-L1+ on NCs were also on IICs. Three types of cancers could be grouped: group A(NCs-/ IICs-); group B (NCs-/ IICs+); group C (NCs+/IICs+). To group A belong tumors characterized by poorly immunogenic competence, poor immune response but massive granulocyte infiltrate, justifying the absence of PD-L1 as an immunoinhibitor receptor. To Group B probably belong more immunogenic CRCs, justifying the strong IICs-mediated immune response, and up-regulation of PD-L1 expression only on IICs. To group C belong CRCs probably characterized by a large amount of tumor neoantigens resulting in a marked infiltration of lymphocytes and PD-L1 upregulation also in NCs.

Materials and Methods

Sixty-three colorectal cancer specimens from a cohort of 61 patients were retrospectively reviewed. Thirty-seven MSS and 26 MSI-H CRCs enrolled in this study. Immunohistochemical staining to PD-L1 was performed by using MAb E1L3N.

Conclusions

Our study calls attention to the importance to assess PD-L1 expression in tumor microenvironment also evaluating type and density of infiltrating immune cells to better stratify CRCs with different immunological patterns.

Differences in histological features and PD-L1 expression between sporadic microsatellite instability and Lynch-syndrome-associated disease in Japanese patients with colorectal cancer

BACKGROUND

The field of immunotherapy has recently focused on cancers with microsatellite instability (MSI). These cancers include both Lynch-syndrome-associated tumors, which are caused by mismatch repair (MMR) germline mutations, and sporadic MSI tumors, which are mainly attributed to MLH1 promoter methylation. The present study aimed to clarify differences in the histological and PD-L1 expression profiles between these two types of MSI cancers in Japanese patients.

METHODS

Among 908 cases of colorectal cancer treated via surgical resection from 2008 to 2014, we identified 64 MSI cancers, including 36 sporadic MSI and 28 Lynch-syndrome-associated cancers, using a BRAF V600E mutation analysis and MLH1 methylation analysis. Of the latter subgroup, 21 (75%) harbored MMR germline mutations.

RESULTS

The following were more frequent with sporadic MSI than with Lynch syndrome associated cancers: poor differentiation (50.0 vs. 7.1%, P = 0.0002), especially solid type (30.6 vs. 3.6%, P = 0.0061); medullary morphology (19.4 and 0%, P = 0.015), Crohn-like lymphoid reaction (50.0 vs. 25.0%, P = 0.042), and PD-L1 expression (25.0 vs. 3.6%, P = 0.034). However, the groups did not differ in terms of the mean invasive front and intratumoral CD8-positive cell densities. In a logistic regression analysis, PD-L1 expression correlated with poor differentiation (odds ratio: 7.65, 95% confidence interval: 1.55-37.7, P = 0.012), but not with the difference between sporadic MSI cancer and Lynch-syndrome-associated cancer (odds ratio: 4.74, 95% confidence interval: 0.50-45.0, P = 0.176).

CONCLUSIONS

Therefore, compared with Lynch-syndrome-associated cancers, sporadic MSI cancers are more frequently solid, poorly differentiated medullary cancers that express PD-L1.

QuPath: Open source software for digital pathology image analysis

QuPath is new bioimage analysis software designed to meet the growing need for a user-friendly, extensible, open-source solution for digital pathology and whole slide image analysis. In addition to offering a comprehensive panel of tumor identification and high-throughput biomarker evaluation tools, QuPath provides researchers with powerful batch-processing and scripting functionality, and an extensible platform with which to develop and share new algorithms to analyze complex tissue images. Furthermore, QuPath's flexible design makes it suitable for a wide range of additional image analysis applications across biomedical research.

QuPath: Open source software for digital pathology image analysis

QuPath is new bioimage analysis software designed to meet the growing need for a user-friendly, extensible, open-source solution for digital pathology and whole slide image analysis. In addition to offering a comprehensive panel of tumor identification and high-throughput biomarker evaluation tools, QuPath provides researchers with powerful batch-processing and scripting functionality, and an extensible platform with which to develop and share new algorithms to analyze complex tissue images. Furthermore, QuPath's flexible design makes it suitable for a wide range of additional image analysis applications across biomedical research.

Is There a Role for Programmed Death Ligand-1 Testing and Immunotherapy in Colorectal Cancer With Microsatellite Instability? Part II—The Challenge of Programmed Death Ligand-1 Testing and Its Role in Microsatellite Instability-High Colorectal Cancer

Context.—

The world of oncology has changed dramatically in the past few years with the introduction of checkpoint inhibitors and immunotherapy. The promising findings of a small, phase 2 clinical trial that led to the US Food and Drug Administration breakthrough designation and approval of the anti–programmed death receptor-1 (PD-1) drug pembrolizumab (Keytruda, Merck, Kenilworth, New Jersey) to treat metastatic/refractory microsatellite instability–high colorectal cancer (CRC) has significantly boosted interest in immunomodulatory therapies in microsatellite instability–high CRC.

Objectives.—

To review the immune response to cancer and the role of immune checkpoints, focusing on the technical and interpretation challenges of PD-1/programmed death ligand-1 (PD-L1) testing by pathologists and the clinical implications of the test and the therapeutic potential of treating CRC with checkpoint inhibitors.

Data Sources.—

A PubMed review was performed of articles pertaining to CRC, microsatellite instability and mismatch repair systems, molecular classification, immune response, PD-1/PD-L1, and immunotherapy.

Conclusions.—

Exciting success with anti–PD-1/PD-L1 and anticytotoxic T-lymphocyte–associated protein 4 (CTLA4) checkpoint inhibitors has already been reported in melanoma and in lung and renal carcinomas. Recently, microsatellite instability–high CRCs, expressing PD-L1 by immunohistochemistry, regardless of the level of that PD-L1 expression, appeared to respond to checkpoint blockades with anti–PD-1 or anti–PD-L1 agents, whereas microsatellite-stable tumors were much less responsive. With microsatellite instability routinely tested by most centers, studies that include larger cohorts are required to study the predictive role of PD-1/PD-L1 expression in microsatellite instability–high CRC, to assess which immunohistochemistry antibodies to use, to refine the scoring criteria, and to critically analyze the interpretation pitfalls.

First Case Report of a Dramatic Radiographic Response to a Checkpoint Inhibitor in a Patient With Proficient Mismatch Repair Gene Expressing Metastatic Colorectal Cancer

Metastatic colorectal cancer (mCRC) remains the second most common cause of cancer death in the United States, and therapeutic options are limited. Recently, the checkpoint inhibitor pembrolizumab was given the Food and Drug Administration breakthrough therapy designation for the treatment of patients with mCRC whose tumors demonstrate deficient mismatch repair gene (dMMR) expression (as evidenced by microsatellite instability–high [MSI-H]). The designation was based on a phase II study showing that in patients with dMMR, an objective response rate of 40% was seen, whereas in patients with proficient mismatch repair gene mCRCs, the response rate was 0%. To our knowledge, this is the first case of a patient with a proficient mismatch repair gene mCRC whose tumor demonstrated a dramatic response to a checkpoint inhibitor. Because this patient’s tumor harbored amplification of both the PD-L1 and PD-L2 genes, the observed response was consistent with the presumed mechanism of action of checkpoint inhibitors. Checkpoint inhibitors are thought to activate a cytotoxic immune response that has been inhibited through tumor expression of PD-L1 and PD-L2. Given this result, dMMR in mCRC may not be the only predictor of responsiveness to checkpoint inhibition. As in non–small-cell lung cancer, PD-L1 or PD-L2 expression (or perhaps gene amplification) may also be predictors of checkpoint inhibitor efficacy.

The Balance Between Cytotoxic T-cell Lymphocytes and Immune Checkpoint Expression in the Prognosis of Colon Tumors

Background

Immune checkpoint (ICK) expression might represent a surrogate measure of tumor-infiltrating T cell (CTL) exhaustion and therefore be a more accurate prognostic biomarker for colorectal cancer (CRC) patients than CTL enumeration as measured by the Immunoscore.

Methods

The expression of ICKs, Th1, CTLs, cytotoxicity-related genes, and metagenes, including Immunoscore-like metagenes, were evaluated in three independent cohorts of CRC samples (260 microsatellite instable [MSI], 971 non-MSI). Their associations with patient survival were analyzed by Cox models, taking into account the microsatellite instability (MSI) status and affiliation with various Consensus Molecular Subgroups (CMS). PD-L1 and CD8 expression were examined on a subset of tumors with immunohistochemistry. All statistical tests were two-sided.

Results

The expression of Immunoscore-like metagenes was statistically significantly associated with improved outcome in non-MSI tumors displaying low levels of both CTLs and immune checkpoints (ICKs; CMS2 and CMS3; hazard ratio [HR] = 0.63, 95% confidence interval [CI] = 0.43 to 0.92, P = .02; and HR = 0.55, 95% CI = 0.34 to 0.90, P = .02, respectively), but clearly had no prognostic relevance in CRCs displaying higher levels of CTLs and ICKs (CMS1 and CMS4; HR = 0.46, 95% CI = 0.10 to 2.10, P = .32; and HR = 1.13, 95% CI = 0.79 to 1.63, P = .50, respectively), including MSI tumors. ICK metagene expression was statistically significantly associated with worse prognosis independent of tumor staging in MSI tumors (HR = 3.46, 95% CI = 1.41 to 8.49, P = .007). ICK expression had a negative impact on the proliferation of infiltrating CD8 T cells in MSI neoplasms (median = 0.56 in ICK low vs median = 0.34 in ICK high, P = .004).

Conclusions

ICK expression cancels the prognostic relevance of CTLs in highly immunogenic colon tumors and predicts a poor outcome in MSI CRC patients.

PD-L1 overexpression in ampulla of Vater carcinoma and its pre-invasive lesions

AIMS

PD-1/PD-L1 checkpoint immunotherapy has been proposed recently as a promising treatment in relapsed/refractory disease, used eventually in combination with traditional chemotherapy in different cancer settings. To date, no data are available concerning PD-L1 expression in ampulla of Vater carcinoma and its pre-invasive lesions.

METHODS AND RESULTS

We assessed the immunohistochemical expression of PD-L1 in a series of 26 ampullary adenocarcinomas, 50 ampullary dysplastic lesions and 10 normal duodenal mucosa samples. Moreover, in all cases DNA mismatch repair proteins status was investigated. PD-L1 was expressed in seven of 26 (26.9%) invasive carcinomas and three of 50 (6.0%) dysplastic samples. Most of the PD-L1-positive tumours (seven of 10) were intestinal-type and poorly differentiated (G3). The number of PD-L1-positive stromal lymphoid cells was significantly higher in dysplastic and invasive lesions than in the normal samples (P = 0.011). Nineteen dysplastic lesions and eight invasive carcinomas did not show any evident epithelial or stromal PD-L1 expression. Four of the carcinomas were mismatch repair-deficient and two of these were PD-L1-positive. Furthermore, mismatch repair-deficient lesions showed a significantly higher average of PD-L1-positive stromal lymphoid cells than those of neoplastic PD-L1-negative samples (62.8 versus 21.6; P < 0.001).

CONCLUSIONS

The present results suggest a role of the PD-1/PD-L1 axis in ampullary adenocarcinomas, and therefore this may also prompt consideration of checkpoint immunotherapy as a novel promising treatment for these tumours.

Correlating programmed death ligand 1 (PD-L1) expression, mismatch repair deficiency, and outcomes across tumor types: implications for immunotherapy

The identification of biomarkers associated with response to therapeutic agents is central to optimizing patient outcomes. Expression of the immune checkpoint proteins PD-1/L1, and DNA mismatch repair deficiency (dMMR) status may be predictive response biomarkers for immunotherapies, but their overlap requires further study. We prospectively conducted PD-L1 and MMR immunohistochemistry (IHC) on 430 consecutive patients with advanced gastrointestinal (GI) cancers, genitourinary (GU) cancers or rare cancers between June 2012 and March 2016. Overall 393/430 (91.4%) patients were evaluable for PD-L1 expression by IHC. The frequency of tumor PD-L1 positivity (PD-L1+) was 16.5% (65/393). Among anatomic tumor sites PD-L1+ was 28.6% in melanoma, 22.2% in GC, 20.9% in CRC, 12.5% in BTC, 7.1% in GU cancer, 6.7% in HCC, 0% in pancreatic cancer and 0% in sarcoma. Among the 394 evaluable for MLH1/MSH2 expression cases, 18 patients (4.5%) had dMMR tumors. The dMMR was most common in GC (7.1%) followed by 6.7% in HCC, 4.4% in CRC, and 2.7% in sarcoma. Of the 365 patients evaluable for both PD-L1 and MLH1/MSH2 expression, there was a significant association between the PD-L1 expression and MLH1/MSH2 loss (P = 0.01), but not with overall survival within tumor types. PD-L1 status and dMMR are overlapping putative response biomarkers in immunoncology. Clinical trials with biomarker enrichment restricted to PD-L1+ or dMMR may be inadequate to capture the subset of patients who may benefit from immune mediated therapies. More robust immunotherapy biomarkers and careful clinical trial design are warranted.

Sensitive detection of PD-L1 expression on circulating epithelial tumor cells (CETCs) could be a potential biomarker to select patients for treatment with PD-1/PD-L1 inhibitors in early and metastatic solid tumors

BACKGROUND

The current cancer research strongly focuses on immune therapies, where the PD-1, with its ligands plays an important role. It is known that PD-L1 is frequently up-regulated in a number of different cancers and the relevance of this pathway has been extensively studied and therapeutic approaches targeting PD-1 and PD-L1 have been developed. We used a non-invasive, real-time biopsy for determining PD-L1 and PD-L2 expression in CETCs of solid cancer patients.

METHODS

CETCs were determined from blood of 128 patients suffering from breast (72), prostate (27), colorectal (18) and lung (11) cancer. The number of vital CETCs and the expression of PD-L1 and PD-L2 were investigated using the maintrac^® method.

RESULTS

PD-L1 expressing CETCs were detected in 94.5% of breast, 100% of prostate, 95.4% of colorectal and 82% of lung cancer patients whereas only 75% of breast cancer patients had PD-L2 positive CETCs. In the PD-L1 and PD-L2 expressing patients the cell fraction of PD-L1 positive CETCs is significantly higher than the fraction of PD-L2 positive CETCs (54.6% vs. 28.7%; p<0.001). Breast cancer patients with metastatic disease had significantly more PD-L1 positive CETCs as compared to patients without metastasis (median 75% vs. 61.1%; p<0.05).

CONCLUSION

PD-L1 seems to be a major factor in immune evasion and is highly expressed on CETCs regardless of the type of cancer. Monitoring the frequency of PD-L1 positive CETCs could reflect individual patient's response for an anti-PD-1/PD-L1 therapy and may be a promising target of anticancer treatment.

Molecular Markers for Colorectal Cancer

Colorectal cancers develop through at least 3 major pathways, including chromosomal instability, mismatch repair, and methylator phenotype. These pathways can coexist in a single individual and occur in both sporadic and inherited colorectal cancers. In spite of the unique molecular and genetic signatures of colorectal cancers, nonspecific chemotherapy based on the antineoplastic effects of 5-fluorouracil is the cornerstone of therapy for stage III and some stage II disease. Techniques to recognize colorectal cancer at the molecular level have facilitated development of new signature drugs designed to inhibit the unique pathways of colorectal cancer growth and immunity.

PD-L1 and immune escape: insights from melanoma and other lineage-unrelated malignancies

One of the major breakthroughs in oncology in the past decade has been the research and development of immune checkpoint inhibitors. Since the discovery of the PD-1/PD-L1 axis as a key mediator in peripheral self-tolerance and the subsequent discovery of its role promoting immune escape in cancers, the PD-1/PD-L1 pathway has produced considerable excitement from both a scientific and therapeutic standpoint. The past decade has seen an explosion in the number of clinical trials utilizing anti-PD-1/PD-L1 therapy. Notably, pathologists have played a critical role in the development of these trials, and in guiding the use of anti-PD-1/PD-L1 therapies in FDA-approved clinical settings. Analysis of tissue biopsies has been increasingly used to predict patients with which cancers are most likely to benefit from these new therapies. However, many open questions remain in a rapidly changing therapeutic and scientific landscape. In this review, we describe the basic functioning of the PD-1/PD-L1 axis in normal biology, how it is coopted by cancers to promote immune escape, and then review the literature regarding the prognostic value of tumoral PD-L1 expression on its own before discussing recent therapeutic advances, and the emerging role for pathologists in predicting response to anti-PD-1/PD-L1 therapies. Special attention is given to melanoma and non-small cell lung cancer, malignancies that have seen the broadest applications of anti-PD-L1/PD-1 therapies.

Prognostic implication of CD274 (PD-L1) protein expression in tumor-infiltrating immune cells for microsatellite unstable and stable colorectal cancer

In this study, we investigated the clinical relevance of CD274 (PD-L1) protein expression by tumor cells and tumor-infiltrating immune cells in colorectal cancer (CRC). To this end, 186 microsatellite instability-high (MSI-H) and 153 microsatellite stable (MSS) CRCs were subjected to immunohistochemistry (IHC) analysis for the expression of CD274 and mismatch repair proteins. CD274 expression was evaluated in tumor cells at the center (TC) and periphery (TP), and immune cells at the center (IC) and periphery (IP) of CRC. IHC slides stained for CD3 and CD8 were scanned using an Aperio ScanScope for precise calculation of tumor-infiltrating T cell density. Additionally, samples were screened for the B-Raf (BRAF)-V600E mutation using a Cobas 4800 System and IHC. In total, CD274TC, CD274TP, CD274IC, and CD274IP were observed in 43 (23.1%), 47 (25.3%), 107 (57.5%), and 102 (54.8%) of the MSI-H CRCs examined, and in three (2.0%), four (2.6%), 47 (30.7%), and 56 (36.6%) of the 153 MSS CRCs tested. Meanwhile, intratumoral heterogeneity of CD274 expression in tumor cells and immune cells was detected in 24 (12.9%) and 47 (25.3%) MSI-H CRCs, respectively. Notably, in both MSI-H and MSS CRC, CD274IC and CD274IP were independently associated with improved prognosis (P < 0.05), while BRAF mutation was associated with CD274TP, poor differentiation, sporadic type, and hMLH1(-)/hMSH2(+)/hMSH6(+)/PMS2(-) in MSI-H CRC (P < 0.006). In conclusion, CD274 expression in tumor-infiltrating immune cells was an independent factor for improved prognosis in CRC patients. A deeper understanding of CD274 status may yield improved responses to future CRC immunotherapies.

PD-L1 protein expression in tumour cells and immune cells in mismatch repair protein-deficient and -proficient colorectal cancer: the foundation study using the SP142 antibody and whole section immunohistochemistry

AIMS

Routine application of PD-L1 immunohistochemistry (IHC) in colorectal cancer (CRC) is limited due to lack of standardized scoring criteria, antibody clones, and intratumoral staining heterogeneity. We assessed PD-L1 protein expression on full face CRC tissue sections and applied two algorithms based on the published clinical trials that support the recent FDA approval for immune checkpoint inhibitors (ICPI) therapy in non-small cell lung cancer (NSCLC).

METHODS

PD-L1/CD274 IHC (Roche/Ventana, clone SP142) was performed on representative tumour blocks from 52 mismatch repair-deficient (MMR-D) and 52 MMR-proficient (MMR-P) CRCs. Membranous PD-L1 expression was scored for the tumour cell (TC) and tumour-infiltrating immune cell (IC) components. PD-L1 positivity status was determined based on the published NSCLC clinical trials that utilized the Ventana SP142 assay. Hybrid capture-based comprehensive genomic profiling (CGP) was performed on a separate set of 2268 clinically advanced CRCs and the frequency of PD-L1/PD-L2 amplification was determined.

RESULTS

PD-L1 expression in the TC and IC correlated with MMR-D (p=0.013, p<0.0001), T stage (p=0.036, p=0.0036) and clinical stage (p=0.022, p=0.0037). PD-L1 positivity status correlated with MMR-D by two algorithms. Five of 2268 (<1%) advansced CRCs demonstrated amplification of either the PD-L1 or PD-L2 genes by CGP.

CONCLUSIONS

PD-L1 expression in TC and IC is associated with advanced stage and MMR-D. PD-L1 positivity status by the published algorithm is associated with MMR-D. PD-L1 amplification is extremely uncommon in CRC. Evaluation of whole tissue section and incorporation of IC staining enhance the sensitivity to screen patients who may benefit from ICPI therapy.

Tumor cell PD-L1 predicts poor local control for rectal cancer patients following neoadjuvant radiotherapy

The tumor cell (TC) PD-L1 expression has been reported by several studies in various types of cancer, and it reduces the cytotoxicity of T-cells toward cancer and evades the anticancer immune response. Herein, our study focuses on the impact of PD-L1 expression in prognosis and the correlation with clinical prognostic factors for local advanced rectal cancer with neoadjuvant radiotherapy (RT). A total of 68 rectal cancer patients treated with neoadjuvant RT were retrospectively enrolled in the present study. PD-L1 expression was investigated using immunohistochemistry. A regression model was used to identify prognostic factors associated with the disease-free survival, the local recurrence-free survival (LRFS), and the overall survival rates. The median follow-up was 32.5 months. Seven patients presented TC PD-L1 positive (TC PD-L1+), while the others were TC PD-L1 negative (TC PD-L1-). TC PD-L1+ patients showed frequent tumor recurrence than TC PD-L1- patients. Several patients with TC PD-L1- underwent long-course RT. TC PD-L1 expression was similar to interstitial cell (IC) PD-L1 expression, and the relationship between IC PD-L1 and pathological T stage was observed. TC PD-L1+ was related to poor LRFS. The multivariate analysis showed TC PD-L1+ as an independent negative prognostic factor for LRFS. In conclusion, TC PD-L1 expression putatively predicts the LRFS for patients with rectal cancer following neoadjuvant RT. The patients with TC PD-L1+ are susceptible to high local recurrent rate, thereby proposing a novel immunotherapeutic strategy for PD-L1 inhibition-mediated control.

Inflammatory cytokines IL-17 and TNF-α up-regulate PD-L1 expression in human prostate and colon cancer cells

Programmed cell death protein 1 (PD-1) acts on PD-1 ligands (PD-L1 and PD-L2) to suppress activation of cytotoxic T lymphocytes. Interleukin-17 (IL-17) and tumor necrosis factor-α (TNF-α) are co-expressed by T helper 17 (T_H17) cells in many tumors. The purpose of this study was to test if IL-17 and TNF-α may synergistically induce PD-L1 expression in human prostate cancer LNCaP and human colon cancer HCT116 cell lines. We found that IL-17 did not induce PD-L1 mRNA expression, but up-regulated PD-L1 protein expression in HCT116 and LNCaP cells. TNF-α induced PD-L1 mRNA and protein expression in both cell lines. Neither IL-17 nor TNF-α induced PD-L2 mRNA or protein expression. IL-17 and TNF-α acted individually rather than cooperatively in induction of PD-L1 expression. IL-17 and/or TNF-α activated AKT, nuclear factor-κB (NF-κB), and extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathways in HCT116 cells, whereas only NF-κB signaling was activated in LNCaP cells. NF-κB inhibitor could diminish PD-L1 protein expression induced by IL-17 and/or TNF-α in both HCT116 and LNCaP cell lines. ERK1/2 inhibitor could also reduce PD-L1 protein expression induced by IL-17 and/or TNF-α in HCT116 cells, while AKT inhibitor could abolish PD-L1 protein expression induced by IL-17 and/or TNF-α in LNCaP cells. These results suggest that IL-17 and TNF-α act individually rather than cooperatively through activation of NF-κB and ERK1/2 signaling to up-regulate PD-L1 expression in HCT116 cells, while the two inflammatory cytokines act through activation of NF-κB signaling, in the presence of AKT activity, to up-regulate PD-L1 expression in LNCaP cells.

Clinicopathologic profile, immunophenotype, and genotype of CD274 (PD-L1)-positive colorectal carcinomas

The CD274 (PD-L1)/PDCD1 (PD-1) pathway is crucial for the modulation of immune responses and self-tolerance. Aberrantly expressed CD274 allows tumor cells to evade host immune system and is considered to be a mechanism of adaptive immune resistance. Inhibition of the CD274/PDCD1 immune checkpoint offers a promising new therapeutic strategy. Although CD274-expressing tumor cells have been identified in different types of tumors including colorectal cancer, clinicopathologic profile of these CD274-positive tumors has not been extensively studied. In this study, 454 primary colorectal carcinomas were analyzed histologically and immunohistochemically for CD274, mismatch repair (MMR) proteins, intestinal differentiation marker (CDX2), and stem cell markers (ALCAM, ALDH1A1, and SALL4). CD274-positive colorectal carcinomas (54/454 (12%)) usually (83%) involved the right or transverse colon with poorly differentiated and solid/medullary histology. On the basis of multivariate logistic regression analysis, CD274 positivity was significantly associated with poorly differentiated histotype (OR: 3.32; 95% CI: 1.46-7.51; P=0.004), MMR deficiency (OR: 10.0; 95% CI: 4.66-21.5; P<0.001), and 'stem-like' immunophenotype defined by the loss or weak expression of CDX2 and ALCAM-positivity (OR: 5.51; 95% CI: 1.66-18.3; P=0.005). Mutation analysis of 66 arbitrary selected colorectal carcinomas revealed that CD274-positive tumors usually (88%) carried the BRAF V600E mutation. Thus, colorectal carcinomas defined by CD274 positivity displayed features associated with tumors arising via the serrated neoplasia pathway. Moreover, colorectal carcinomas characterized by lack of CDX2 and prominent expression of ALCAM frequently (71%) showed CD274 positivity. This might suggest association of CD274 expression with 'stem-like' phenotype. Further evaluation of a larger cohort or experimental analyses would be needed to confirm this notion.