Assessment of the PD-L1 status by immunohistochemistry: challenges and perspectives for therapeutic strategies in lung cancer patients

Prognostic Value of Programmed Cell Death 1 Ligand-1 in Patients With Bone and Soft Tissue Sarcomas: A Systemic and Comprehensive Meta-Analysis Based on 3,680 Patients

Background: Programmed cell death 1 ligand-1 (PD-L1) is an immune checkpoint molecule that acts to protect cancer cells from immune surveillance and is considered as a prognostic biomarker in several cancers, but the prognostic value of PD-L1 in bone and soft tissue sarcomas remains inconclusive. In the present meta-analysis, the clinicopathological and prognostic value of PD-L1 in sarcomas was evaluated.

Method: We performed a systemic and comprehensive meta-analysis by searching the PubMed, Medline, Cochrane Library, EMBASE, and Web of Science databases up to October 31, 2019. Eligible articles were incorporated, and pooled hazard ratios (HRs) and odds ratios (ORs) with their 95% confidence intervals (CIs) were used to estimate the outcomes.

Results: Thirty-six articles containing 39 independent studies with 3,680 bone and soft tissue sarcoma patients were included in our meta-analysis. The pooled results showed that PD-L1 overexpression could predict poor overall survival (HR 1.45, 95% CI 1.11–1.90, P < 0.01), metastasis-free survival (HR 1.58, 95% CI 1.14–2.19, P < 0.01), and event-free survival (HR 2.82, 95% CI 1.69–4.71, P < 0.01) in sarcomas. Furthermore, PD-L1 overexpression was correlated with a higher rate of tumor metastasis (OR 2.95, 95% CI 1.32–6.60, P < 0.01), a more advanced tumor grade (OR 3.63, 95% CI 2.55–5.16, P < 0.01), and more T lymphocyte infiltration (OR 5.55, 95% CI 2.86–10.76, P < 0.01). No obvious publication bias was observed, and the sensitivity analysis showed that our results were robust.

Conclusion: The results of our meta-analysis indicate that high PD-L1 expression might serve as a valuable and predictive biomarker for adverse clinicopathological features and poor prognosis in patients with sarcoma.

Development and applications of computer image analysis algorithms for scoring of PD-L1 immunohistochemistry

Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) have rapidly become integral to standard-of-care therapy for non-small cell lung cancer and other cancers. Immunohistochemical (IHC) staining of PD-L1 is currently the accepted and approved diagnostic assay for selecting patients for PD-L1/PD-1 axis therapies in certain indications. However, the inherent biological complexity of PD-L1 and the availability of several PD-L1 assays – each with different detection systems, platforms, scoring algorithms and cut-offs – have created challenges to ensure reliable and reproducible results based on subjective visual assessment by pathologists. The increasing adoption of computer technologies into the daily workflow of pathology provides an opportunity to leverage these tools towards improving the clinical value of PD-L1 IHC assays. This review describes several image analysis software programs of computer-aided PD-L1 scoring in the hope of driving further discussion and technological advancement in digital pathology and artificial intelligence approaches, particularly as precision medicine evolves to encompass accurate simultaneous assessment of multiple features of cancer cells and their interactions with the tumor microenvironment.

TMB: a promising immune-response biomarker, and potential spearhead in advancing targeted therapy trials

Immune checkpoint inhibition (ICI) has revolutionized cancer treatment, and produced durable responses in many cancer types. However, there remains a subset of patients that do not respond despite their tumors exhibiting PD-L1 expression, which highlights the need for additional biomarkers relevant to response. Here, we review checkpoint inhibitor signal pathways, resistance and sensitivity mechanisms, as well as response rates. We also investigate the correlation and response to ICI with BRCA1/2 mutation status and homologous recombination deficient tumors. Collectively we show that the use of tumor mutational burden may be effective as an emerging biomarker.

EBUS-FNA cytologic-histologic correlation of PD-L1 immunohistochemistry in non-small cell lung cancer

INTRODUCTION

Immune checkpoint pathway markers induce immune tolerance to non-small cell lung cancer (NSCLC). Therapeutic antibodies targeting the programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway have demonstrated efficacy in tumors expressing relatively high PD-L1 levels. Minimally invasive endobronchial ultrasound-guided fine needle aspiration allows patients with inoperable tumors or comorbidities to attain a confirmatory diagnosis. The aims of the present study were to determine whether PD-L1 testing is equivalent to cytology and biopsy or resection specimens at different tumor proportion score cutoffs and for different NSCLC subtypes.

MATERIALS AND METHODS

Data were retrospectively collected for patients with paired NSCLC cytology and surgical resection specimens from May 4, 2007 to May 4, 2017. The Food and Drug Administration-approved Dako PD-L1 immunohistochemistry 22C3 pharmDx kit was used to measure PD-L1 on paired cytology cell block and biopsy or resection specimens, and the PD-L1 tumor proportion scores were recorded. Statistical analysis of categorical and continuous variables was performed using SAS, version 9.4.

RESULTS

A total of 53 paired cytology and resection samples (27 adenocarcinoma, 25 squamous cell carcinoma, and 1 unclassified) were analyzed. Supposing the resection specimen to reflect the true PD-L1 expression, the sensitivity, specificity, positive predictive value, negative predictive value, and overall agreement for the cytology method was 73.3%, 65.2%, 73.3%, 65.2%, and 69.8%, respectively. For high PD-L1 expression (≥50%), the cytology method demonstrated an overall agreement of 79.2%. The overall agreement between methods was 81.5% and 76% for cases of adenocarcinoma and squamous cell carcinoma, respectively.

CONCLUSIONS

NSCLC cytology samples from endobronchial ultrasound-guided fine needle aspiration are suitable for PD-L1 testing, especially using a high PD-L1 expression cutoff of ≥50% and for adenocarcinoma.

Pitfalls and controversies in pathology impacting breast cancer management

Introduction: Breast cancer is a heterogeneous disease, at morphological, molecular, and clinical levels and this has significant implications for the diagnosis and management of the disease. The introduction of breast screening, and the use of small tissue sampling for diagnosis, the recognition of new morphological and molecular subtypes, and the increasing use of neoadjuvant therapies have created challenges in pathological diagnosis and classification.Areas covered: Areas of potential difficulty include columnar cell lesions, particularly flat epithelial atypia, atypical ductal hyperplasia, lobular neoplasia and its variants, and a range of papillary lesions. Fibroepithelial, sclerosing, mucinous, and apocrine lesions are also considered. Established and newer prognostic and predictive markers, such as immune infiltrates, PD-1 and PD-L1 and gene expression assays are evaluated. The unique challenges of pathology assessment post-neoadjuvant systemic therapy are also explored.Expert opinion: Controversies in clinical management arise due to incomplete and sometimes conflicting data on clinicopathological associations, prognosis, and outcome. The review will address some of these challenges.

Infiltration of tumor-associated macrophages is involved in tumor programmed death-ligand 1 expression in early lung adenocarcinoma

Programmed death-ligand 1 (PD-L1) is an immune modulator that promotes immunosuppression by binding to programmed death-1 of T-lymphocytes. Although tumor cell PD-L1 expression has been shown to be associated with the clinical response to anti-PD-L1 antibodies, its concise regulatory mechanisms remain elusive. In this study, we evaluated the associations of tumor PD-L1 expression and immune cell infiltrating patterns in 146 cases of early lung adenocarcinoma (AC) to investigate the possible extrinsic regulation of tumor PD-L1 by immune cells. Using immunohistochemistry, cell surface PD-L1 expression in tumor cells was observed in 18.5% of stage 0-IA lung AC patients. Tumor PD-L1 positivity was significantly associated with stromal invasion, which was accompanied by increased tumor-associated macrophages (TAM), CD8⁺ cytotoxic T cells and FoxP3⁺ regulatory T cells. Among these immune cells, TAM and CD8⁺ T cells significantly accumulated in PD-L1-positive carcinoma cell areas, which showed a tumor cell nest-infiltrating pattern. Although CD8⁺ T cells are known to induce tumor PD-L1 expression via interferon-ɣ production, the increased TAM within tumors were also associated with tumor cell PD-L1 positivity, independently of CD8⁺ T cell infiltration. Our in vitro experiments revealed that PD-L1 expression in lung cancer cell lines was significantly upregulated by co-culture with M2-differentiated macrophages; expression of PD-L1 was reduced to baseline levels following treatment with a transforming growth factor-β inhibitor. These results demonstrated that tumor-infiltrating TAM are extrinsic regulators of tumor PD-L1 expression, indicating that combination therapy targeting both tumor PD-L1 and stromal TAM might be a possible strategy for effective treatment of lung cancer.

Programmed Death Ligand 1 (PD-L1) as a Predictive Biomarker for Pembrolizumab Therapy in Patients with Advanced Non-Small-Cell Lung Cancer (NSCLC)

Recently, immunotherapy has been shown to be an effective and helpful therapeutic option for the treatment of advanced non-small-cell lung cancer (NSCLC). The activity of antitumor T cells may be restored through the checkpoint blockade using anti-programmed death 1 or anti-programmed death ligand 1 (PD-L1) antibodies, showing, in several cancer patients, an increased progression-free survival and overall survival compared with classical chemotherapy. As recently shown by several studies, the PD-L1 expression levels in tumors may offer a selection criterion for patients to predict their immunotherapy response. In particular, NSCLC patients with high tumor PD-L1 levels (proportional score ≥ 50% for first-line therapy and ≥ 1% for second-line treatment, respectively) showed better response rates to immunotherapy and longer survival in first-line therapy compared with conventional chemotherapy. PD-L1, whose expression is evaluated by using immunohistochemistry analysis, is currently the only biomarker approved for clinical use in the first- and second-line monotherapy setting and therefore plays a central role in treatment decision-making for patients with advanced NSCLC. In this review we will discuss the key role of PD-L1 as a predictive biomarker of response to pembrolizumab therapy in NSCLC patients by describing the appropriate techniques and methodologies for immunohistochemical evaluation of PD-L1 expression and providing an overview of the clinical studies supporting its predictive significance.

Programmed death ligand-1/programmed death-1 inhibition therapy and programmed death ligand-1 expression in urothelial bladder carcinoma

After two decades of unchanged paradigms, the treatment strategies for advanced urothelial bladder cancer have been revolutionized by emerging programmed death ligand-1 (PD-L1)/programmed death-1 (PD1) inhibition therapy. Increased evidence is demonstrating the efficacy of PD-L1/PD1 inhibition therapy in both second-line and first-line settings. However, the percentage of patients who benefit from anti-PD-L1/anti-PD1 therapy is still low. Many questions have been raised in the development of biomarker-driven approaches for disease classification and patient selection. In this perspective, we discuss PD-L1/PD1 expression in urothelial bladder carcinoma, review approved anti-PD-L1/anti-PD1 agents for bladder cancer treatment and current ongoing studies investigating combination treatment strategies, and explore PD-L1 expression status for the evaluation of bladder cancer immunotherapy.

Expression and clinical significance of PD-L1 and c-Myc in non-small cell lung cancer

BACKGROUND

It is known that there are insufficient prognostic factors for non-small cell lung cancer (NSCLC). It was reported that PD-L1 was a prognostic factor for NSCLC,and c-Myc regulated the expression of PD-L1. Herein, we investigated c-Myc and PD-L1 expression and their association with overall survival (OS) in NSCLC.

METHODS

Formalin-fixed paraffin-embedded specimens were obtained from 128 patients with surgically resected primary NSCLC. Immunohistochemistry was used to assess the expression of PD-L1 and c-Myc in this study. Pearson's Chi squared test or Fisher's exact test was used to analyze the correlation of the expression of PD-L1 and c-Myc with clinicopathologic features. The relationship between OS and the expression of PD-L1 and c-Myc was evaluated by the Kaplan-Meier method and Cox proportional hazards model, respectively.

RESULTS

Positive expression of PD-L1 was detected in 59 patients (46.1%). Patients with negative expression of PD-L1 had remarkably longer OS than those with positive expression of PD-L1. The positive expression rate of c-Myc in NSCLC accounted for 58.6% (75/128) and its expression was significantly more frequent in males (p = 0.002) and patients with lymph node metastasis (p = 0.029). PD-L1 expression was positively correlated with c-Myc expression (r = 0.459, p < 0.001). The PD-L1 and c-Myc double-positive group had a worse prognosis than other subgroups (p < 0.05), and the PD-L1 and c-Myc double-negative group had a better OS than other subgroups (p < 0.05).

CONCLUSION

Conjoint analysis of the expression of PD-L1 and c-Myc was a better prognostic approach for NSCLC patients.

Independent expression of circulating and tissue levels of PD-L1: correlation of clusters with tumor metabolism and outcome in patients with non-small cell lung cancer

PURPOSE

To evaluate the clinical-pathological and prognostic significance of the circulating PD-L1 level in patients with surgically treated NSCLC, by combining data for PD-L1 expression with other immune-related markers and tumor metabolism.

METHODS

Overall, 40 patients with resected NSCLC (stage Ia-IIIa) who had preoperative blood storage and underwent staging PET/CT were enrolled for the study. In all cases, we determined plasma levels of PD-L1 (pg/ml), immune-reactive areas (IRA %) covered by CD3, CD68, CD20, CD8, PD-1, and PD-L1 in the tumor specimen, and metabolic parameters on PET, i.e., SUV_max, SUV_peak, metabolic tumor volume (MTV), and total lesion glycolysis (TLG). Variables were statistically analyzed to establish their association with disease-free survival (DFS).

RESULTS

The circulating levels of PD-L1 in the bloodstream could be determined in 38/40 (95%) samples. The mean and median expression levels were 34.86 pg/ml and 24.83 pg/ml, respectively. We did not find any statistically significant correlation between circulating PD-L1 and tissue expression of PD-L1/PD-1. Some mild degree of positive correlation was determined between tissue PD-L1 and SUV_max (ρ = 0.390; p = 0.0148). Hierarchical clustering combining circulating, tissue, and metabolic parameters identified clusters with high metabolic tumor burden or high expression of plasma PD-L1 levels (Z score ≥ 2) as having a poor DFS (p = 0.033). The multivariate analysis detected stage and metabolism (i.e., SUV_max and SUV_peak) as independent prognostic factors for DFS.

CONCLUSION

Plasma levels of PD-L1 are independent of the expression of PD-1/PD-L1 in NSCLC tumor tissue and, when combined with other clinical-pathological parameters, allow for the identification of clusters with different outcomes.

Diagnostic Utility of PD-L1 Expression in Lung Adenocarcinoma: Immunohistochemistry and RNA In Situ Hybridization

BACKGROUND

Programmed death receptor and programmed death ligand (PD-L1) are immunoregulatory proteins. Nonsmall cell lung cancer bypasses the immune system through the induction of protumorigenic immunosuppressive changes. The better understanding of immunology and antitumor immune responses has brought the promising development of novel immunotherapy agents like programmed death receptor checkpoint inhibitors. The aim of this study was to investigate the expression of PD-L1 in lung adenocarcinoma (ADC), comparing 2 different technologies: immunohistochemistry (IHC) by 2 methods versus RNA in situ hybridization (RISH).

METHODOLOGY

In total, 20 cases of ADC of the lung and 4 samples of metastatic colon ADC were selected. Evaluation of PD-L1 expression was performed by IHC and RISH. RISH was performed using RNAscope. Both methods were scored in tumor cells and quantified using combined intensity and proportion scores.

RESULTS

Eight of 20 (40%) lung ADC and 2 of 4 (50%) colon ADC were positive for PD-L1 with Cell Signaling IHC, and 65% lung ADC were positive by Dako IHC (13/20). All 4 cases of colon ADC were negative. When evaluated by RISH, 12 lung ADC (60%) and 1 colon ADC (25%) were PD-L1 positive.

CONCLUSIONS

RNAscope probes provide sensitive and specific detection of PD-L1 in lung ADC. Both IHC methods (Cell Signaling and Dako) show PD-L1 expression, with the Dako method more sensitive (40% vs. 65%). This study illustrates the utility of RISH and Cell Signaling IHC as complementary diagnostic tests, and Food and Drug Administration approved Dako IHC as a companion diagnostic test.

Elevated platelet-to-lymphocyte corresponds with poor outcome in patients with advanced cancer receiving anti-PD-1 therapy

OBJECTIVES

The purpose of this retrospective analysis was to investigate the prognostic value of PLR for PD-1 inhibitors.

METHODS

Patients were divided into different subgroups according to PLR. Univariate survival analysis and a multivariate Cox proportional hazards regression model were used to assess the association between PLR and overall survival (OS) or progression-free survival (PFS).

RESULTS

The optimal cut-off value of baseline PLR was 164. Among the total 85 patients, 34 patients presented with PLR ≥ 164, and 51 presented with PLR < 164, respectively. The median OS for the high PLR group was 7.0 months (95% CI: 4.1-9.9 months), and it was not reached for the low PLR group (P < 0.001). The median PFS was 3.0 months (95% CI: 1.9-4.1 months) vs. 9.8 months (95% CI: 6.1-13.5 months) for the high and low PLR groups, respectively (P < 0.001). In multivariate analysis, a PLR > 164 and body mass index (BMI) > 24.0 were independently associated with OS (hazard ratio [HR]: 3.549, 95% confidence interval [CI]: 1.901-6.625, P < 0.001 and HR: 0.496, 95% CI: 0.260-0.945, P = 0.033), meanwhile PLR was also significantly associated with inferior PFS (HR: 2.567, 95% CI: 1.551-4.249, P < 0.001). Disease control rate for high and low PLR group was 38.2% and 74.5%, respectively, and it was also correlated with elevated PLR (P = 0.001).

CONCLUSION

This retrospective analysis indicates that PLR could be used as a biomarker to stratify patients who will have a better response to anti-PD-1 agents.

Update on liquid biopsy in clinical management of non-small cell lung cancer

Lung cancer, a leading cause of cancer-related mortality, has a low rate of early diagnosis and a poor prognosis for advanced stages. Recent advances in further mastery of the biology of tumors promote the diagnosis and therapy, especially for non-small cell lung cancer (NSCLC). However, tumor tissue-based information is often not available in most cases due to the invasive and high risk nature of the tumor biopsy procedures. Liquid biopsy, based on the multiple liquid samples including circulating tumor cells (CTC), circulating tumor DNA (ctDNA), and tumor-derived exosome obtained from blood or urine as well as other body fluids, can also provide valuable tumor-related information, playing an important role in management of NSCLC in clinical practice. It is widely believed that concordance of detection for tumor by liquid samples in comparison with tissue biopsy for both early and advanced stage NSCLC patients is optimistic. We herein review the current and future clinical application of liquid biopsy, including early diagnosis and management of precise personalized treatment in lung cancer. The future directions of development for liquid biopsy are also discussed in this review.

Programmed death-ligand 1 expression on direct Pap-stained cytology smears from non-small cell lung cancer: Comparison with cell blocks and surgical resection specimens

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression, as assessed by immunohistochemistry (IHC), is used to select patients with non-small cell lung cancer (NSCLC) for anti-programmed cell death protein 1 (PD-1)/PD-L1 therapy. The current study evaluated the feasibility and efficacy of PD-L1 immunostaining and quantitation on direct Papanicolaou-stained cytological smears compared with formalin-fixed paraffin-embedded samples (cytological cell blocks and surgical resection specimens) in NSCLC cases using 2 commercially available assays: the PD-L1 IHC 22C3 pharmDx assay (Agilent Technologies/Dako, Carpinteria, CA, USA) and the Ventana SP263 Assay (Ventana Medical Systems Inc, Tucson, Arizona).

METHODS

PD-L1 immunostaining using either both or one of the assays was tested in 117 sets of paired samples obtained from 62 NSCLC cases. The tumor proportion score was reported in every case following the recommendations of the International Association for the Study of Lung Cancer (IASLC).

RESULTS

In 57 sets of samples, both PD-L1 assays were used. Due to the availability of samples, only 1 assay was performed in 3 sets of samples and in 2 cases, only cytology smears were used and tested for both assays. A total of 113 sets of paired samples finally were evaluated; 4 cases could not be studied due to intense nonspecific background staining. A significant concordance between the 2 assays on cytological smears was found. Concordance between paired cytological smears and formalin-fixed paraffin-embedded samples was observed in 97.3% of the cases.

CONCLUSIONS

The quantification of PD-L1 expression on direct Papanicolaou-stained cytology smears is feasible and reliable for both PD-L1 assays.

18F-FDG PET metabolic-to-morphological volume ratio predicts PD-L1 tumour expression and response to PD-1 blockade in non-small-cell lung cancer

PURPOSE

Anti-PD-1/PD-L1 blockade can restore tumour-specific T-cell immunity and is an emerging therapy in non-small-cell lung cancer (NSCLC). We investigated the correlation between ¹⁸F-FDG PET/CT-based markers and tumour tissue expression of PD-L1, necrosis and clinical outcome in patients receiving checkpoint inhibitor treatment.

METHODS

PD-Li expression in biopsy or resection specimens from 49 patients with confirmed NSCLC was investigated by immunohistochemistry. Maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were obtained from ¹⁸F-FDG PET/CT images. The ratio of metabolic to morphological lesion volumes (MMVR) and its association with PD-L1 expression in each lesion were calculated. The associations between histologically reported necrosis and ¹⁸F-FDG PET imaging patterns and radiological outcome (evaluated by iRECIST) following anti-PD-1/PD-L1 therapy were also analysed. In 14 patients, the association between necrosis and MMVR and tumour immune contexture were analysed by multiple immunofluorescent (IF) staining for CD8, PD-1, granzyme B (GrzB) and NFATC2.

RESULTS

In total, 25 adenocarcinomas and 24 squamous cell carcinomas were analysed. All tumours showed metabolic ¹⁸F-FDG PET uptake. MMVR was correlated inversely with PD-L1 expression in tumour cells. Furthermore, PD-L1 expression and low MMVR were significantly correlated with clinical benefit. Necrosis was correlated negatively with MMVR. Multiplex IF staining showed a greater frequency of activated CD8⁺ cells in necrotic tumours than in nonnecrotic tumours in both stromal and epithelial tumour compartments.

CONCLUSION

This study introduces MMVR as a new imaging biomarker and its ability to noninvasively capture increased PD-L1 tumour expression and predict clinical benefit from checkpoint blockade in NSCLC should be further evaluated.

A Syngeneic ErbB2 Mammary Cancer Model for Preclinical Immunotherapy Trials

In order to develop a practical model of breast cancer, with in vitro and syngeneic, immune-intact, in vivo growth capacity, we established a primary cell line derived from a mammary carcinoma in the transgenic FVB/N-Tg(MMTV-ErbB2*)NDL2-5Mul mouse, referred to as "NDL^UCD". The cell line is adapted to standard cell culture and can be transplanted into syngeneic FVB/N mice. The line maintains a stable phenotype over multiple in vitro passages and rounds of in vivo transplantation. NDL^UCD tumors in FVB/N mice exhibit high expression of ErbB2 and ErbB3 and signaling molecules downstream of ErbB2. The syngeneic transplant tumors elicit an immune reaction in the adjacent stroma, detected and characterized using histology, immunophenotyping, and gene expression. NDL^UCD cells also express PD-L1 in vivo and in vitro, and in vivo transplants are reactive to anti-immune checkpoint therapy with responses conducive to immunotherapy studies. This new NDL^UCD cell line model is a practical alternative to the more commonly used 4T1 cells, and our previously described FVB/N-Tg(MMTV-PyVT)634Mul derived Met-1^fvb2 and FVB/NTg(MMTV-PyVT^Y315F/Y322F) derived DB-7^fvb2 cell lines. The NDL^UCD cells have, so far, remained genetically and phenotypically stable over many generations, with consistent and reproducible results in immune intact preclinical cohorts.

Combined prognostic value of CD274 (PD-L1)/PDCDI (PD-1) expression and immune cell infiltration in colorectal cancer as per mismatch repair status

The CD274 (programmed cell death ligand-1, PD-L1)/PDCD1 (programmed cell death-1, PD-1) pathway is crucial suppressor of the cytotoxic immune response. Antibodies targeting CD274 or PDCD1 have been revealed to be effective in several malignancies. In colorectal cancer, the response to CD274/PDCD1 blockage is associated with microsatellite instability. However, the value of CD274/PDCD1 for predicting response to treatment or survival benefit is still unclear. The aims of the study were (1) to clarify differences in immune microenvironment and expression of checkpoint proteins (CD274/PDCD1) in DNA mismatch repair-proficient, mismatch repair-deficient, and hereditary Lynch syndrome-associated colorectal cancer, and (2) to assess the prognostic value of these factors and their combinations. Ninety-four mismatch repair-deficient colorectal cancers, 100 age, sex, and AJCC/UICC stage-matched mismatch repair-proficient colorectal cancers, and 48 Lynch syndrome-associated colorectal cancers were analyzed. Using whole section samples, detailed analysis of immune cell score, PDCD1, and CD274 expression was performed. Overlapping of CD274 expression in tumor and immune cells was almost complete (95%). Immune cell score and CD274/PDCD1 positivity were significantly more frequent in mismatch repair-deficient than in mismatch repair-proficient colorectal cancers (70% vs. 41% (high immune cell score); 81% vs. 49% (PDCD1^high), 23% vs. 1% (CD274 on tumor cells) and 68% vs. 30% (CD274 on immune cells), P < 0.001), and were associated strongly with each other. Although the independent impact of immune cell score, PDCD1, and CD274 on immune cells was moderate, the immunoprofile parameter combining the above three factors appeared to be a strong independent prognostic factor for disease-specific survival and overall survival (P = 0.001) and had suggestive impact on disease-free survival (P = 0.011). Our results encourage the use of immune cell score analysis together with PDCD1 and CD274 detection to improve the prognostic evaluation of colorectal cancer patients. Particularly, the analyses from whole tissue sections are encouraged to allow reliable and cell-specific analyses of CD274 expression.

Programmed death receptor Ligand 1 expression in eyelid sebaceous carcinoma: a consecutive case series of 41 patients

PURPOSE

A limited number of therapies are available for patients with metastatic eyelid sebaceous carcinoma (SC). Programmed death receptor Ligand 1 (PD-L1) expression and its clinical significance in sebaceous cell carcinoma are presently unknown. This study aimed to evaluate the expression level of PD-L1 in SC.

METHODS

This single centre, retrospective, and comparative study was conducted at the Ninth People's Hospital between August 1, 2013 and September 1, 2016. Twenty primary, 11 recurrent, and 10 lymph node metastatic eyelid SCs of 41 consecutive patients and paired control eyelid samples were enrolled in the study. Immunohistochemical staining of PD-L1 was performed on slides containing SC embedded in paraffin wax. Patient clinical characteristics and PD-L1 expression related to SC prognostic values were evaluated.

RESULTS

Of the 41 patients with eyelid SCs, 58.5% (24/41) were female, and 41.5% (17/41) were male. A total of 43.9% (18/41) were left-sided, and 56.1% (23/41) were right-sided. A total of 2.4% (1/41) of the SCs were located at the canthus, 51.2% (21/41) were located at the upper eyelid, 41.5% (17/41) were located at the lower eyelids, and 2.4% (1/41) invaded the lacrimal sac. A total of 24.4% of the SCs were metastatic (10/41), 48.8% (20/41) were primary tumours, and 26.8% (11/41) resulted from recurrence. A total of 48.8% (20/41) were moderately graded and 51.2% (21/41) were poorly graded. Programmed death receptor Ligand 1 (PD-L1) positive expression was found in 20 (48.8%) cases. Programmed death receptor Ligand 1 (PD-L1) expression was observed on the tumour cell membrane. Higher expression of PD-L1 was correlated with metastatic cases when compared with primary cases (F = 6.69, p = 0.001). There was a higher expression of PD-L1 in the poorly differentiated group compared with the moderately graded group (57.1% poorly graded versus 45.0% moderately graded).

CONCLUSION AND RELEVANCE

Inhibition of PD-L1 expression may be a therapeutic option for metastatic eyelid SCs, although this hypothesis needs to be tested in future clinical trials.

Comparative study of the PD-L1 expression and CD8+ tumor-infiltrating lymphocyte between surgically resected and matched re-biopsy specimens in recurrent non-small cell lung cancer

Introduction: Numerous studies conducted until date have reported that the chemotherapy regimen could affect the programmed cell death ligand 1 (PD-L1) expression status in patients with non-small cell lung cancer (NSCLC).

Materials and methods: A total of 36 NSCLC patients for whom both the surgically resected specimens of the primary tumors and re-biopsy specimens of the recurrent tumors were available were enrolled in this study. The PD-L1 expression status and tumor-infiltrating CD8-positive T lymphocytes (CD8+TILs) count were measured in paired samples by immunohistochemistry. The concordance rate in the tumor immune microenvironment (TIME) classification based on the PD-L1 expression status and CD8+TILs count was analyzed.

Results: While the PD-L1 expression levels were similar between the surgical and re-biopsy specimens in 77.8% of cases, in 16.7% of cases, the expression levels were higher in the re-biopsy specimens. When the analysis was confined to patients who had received platinum-based chemotherapy, the percentage increased to 42.9%. The TIME classification changed in the re-biopsy specimens as compared to the surgical specimens in one-third of the patients, especially in those who had received chemotherapy previously. The TIME classification in the re-biopsy specimens more closely resembled that in the metastatic lymph nodes as compared to that in the primary tumor.

Conclusion: In patients with recurrent NSCLC, especially those who have received chemotherapy previously, a recent re-biopsy sample is required to determine whether PD-1/PD-L1 inhibitors should be used for treatment or not.

Perspectives of Induction With Chemo and/or Immune Check Point Inhibition in Head and Neck Organ Preservation Treatment

Induction chemotherapy (ICT) is an attractive option for advanced head and neck squamous cell carcinoma (HNSCC) patients which has been prospectively evaluated in the context of a multimodality treatment approach. The theoretical benefit is the ability to suppress distant metastases and shrink the tumor while chemotherapy is better tolerated when given sequentially than concurrently. However, clinical trials have failed to show consistent benefit of ICT over concurrent radio-chemotherapy and due to so far lacking level 1 evidence ICT outside larynx organ preservation remains rather investigational. Immune modulation by inhibition of immune checkpoints is an exciting recent development in HNSCC which has mainly been investigated as second line treatment after progression on platinum-based chemotherapy in patients with recurrent/metastatic HNSCC. Due to the promising results in these trials and even more in the first-line trial KEYNOTE-048 and encouraging first preliminary results of preoperative Anti-PD1-application, the role of neoadjuvant immunotherapy is currently under investigation in HNSCC.

Comprehensive Assessment of PD-L1 Staining Heterogeneity in Pulmonary Adenocarcinomas Using Tissue Microarrays: Impact of the Architecture Pattern and the Number of Cores

Checkpoint inhibitors directed against programmed death receptor 1 (PD-1) and its ligand (PD-L1) changed the treatment of advanced lung non-small cell carcinomas. The decision to treat patients is influenced by PD-L1 expression by tumor cells, but evidence indicates that this staining is heterogenous within a tumor. As PD-L1 staining is tested mostly on biopsies, false negative results can occur due to sampling issues. The clinical impact of this heterogeneity has not been established. We selected 241 patients who underwent pulmonary resection for adenocarcinoma. Tissue microarrays were constructed with five 1 mm cores representative of the histologic patterns observed in each tumor and stained for PD-L1. For each core, the histologic pattern and the percentage of PD-L1 positive tumor cells were noted. Staining heterogeneity was defined as cases with both positive and negative cores at positivity thresholds of 1%, 10%, and 50% of tumor cells. At the 50% cut-off, 37.8% of patients were PD-L1 positive, whereas 22.4% showed staining heterogeneity. Among patients with 1 negative core, 26.5% also had a positive core and could have been misclassified based on 1 biopsy. Mean staining of PD-L1 was higher in solid (47.9%) and micropapillary (24.2%) patterns and was lower in acinar (14.1%), papillary (3.4%), and lepidic (6.4%) architectures. A significant proportion of patients presented a heterogenous staining for PD-L1. A total of 26.5% of patients negative on 1 core turned out to be positive on another core, which raises the consideration of rebiopsy, in particular when lepidic, acinar, or papillary patterns are observed on a biopsy.

Multiplexed Immunohistochemistry for Molecular and Immune Profiling in Lung Cancer-Just About Ready for Prime-Time?

As targeted molecular therapies and immuno-oncology have become pivotal in the management of patients with lung cancer, the essential requirement for high throughput analyses and clinical validation of biomarkers has become even more intense, with response rates maintained in the 20%–30% range. Moreover, the list of treatment alternatives, including combination therapies, is rapidly evolving. The molecular profiling and specific tumor-associated immune contexture may be predictive of response or resistance to these therapeutic strategies. Multiplexed immunohistochemistry is an effective and proficient approach to simultaneously identify specific proteins or molecular abnormalities, to determine the spatial distribution and activation state of immune cells, as well as the presence of immunoactive molecular expression. This method is highly advantageous for investigating immune evasion mechanisms and discovering potential biomarkers to assess mechanisms of action and to predict response to a given treatment. This review provides views on the current technological status and evidence for clinical applications of multiplexing and how it could be applied to optimize clinical management of patients with lung cancer.

Integrated Approaches for the Use of Large Datasets to Identify Rational Therapies for the Treatment of Lung Cancers

The benefit and burden of contemporary techniques for the molecular characterization of samples is the vast amount of data generated. In the era of “big data”, it has become imperative that we develop multi-disciplinary teams combining scientists, clinicians, and data analysts. In this review, we discuss a number of approaches developed by our University of Texas MD Anderson Lung Cancer Multidisciplinary Program to process and utilize such large datasets with the goal of identifying rational therapeutic options for biomarker-driven patient subsets. Large integrated datasets such as the The Cancer Genome Atlas (TCGA) for patient samples and the Cancer Cell Line Encyclopedia (CCLE) for tumor derived cell lines include genomic, transcriptomic, methylation, miRNA, and proteomic profiling alongside clinical data. To best use these datasets to address urgent questions such as whether we can define molecular subtypes of disease with specific therapeutic vulnerabilities, to quantify states such as epithelial-to-mesenchymal transition that are associated with resistance to treatment, or to identify potential therapeutic agents in models of cancer that are resistant to standard treatments required the development of tools for systematic, unbiased high-throughput analysis. Together, such tools, used in a multi-disciplinary environment, can be leveraged to identify novel treatments for molecularly defined subsets of cancer patients, which can be easily and rapidly translated from benchtop to bedside.

Nuclear localization of PD-L1: artifact or reality?

BACKGROUND

The levels of expression and membrane localization of programmed cell death ligand 1 (PD-L1), an immune checkpoint type I transmembrane glycoprotein, are related to the clinical response of anti-PD-L1/PD-1 therapy. Although the biologically relevant localization of PD-L1 is on the plasma membrane of cancer cells, it has also been reported to be in the cytoplasm and sometimes in the nucleus. Furthermore, it has been claimed that chemotherapeutics can modify PD-L1 expression and/or its nuclear localization.

RESULTS

Data from our group suggest that the nuclear localization of PD-L1, and other plasma membrane proteins as well, could be an artifact resulting from inadequate experimental conditions during immunocytochemical studies. Mild detergent and rigorous fixation conditions should be used in order to preserve the membrane localization and to prevent an erroneous translocation of PD-L1 and other non-interconnected membrane proteins, such as CD24, into other cellular compartments including the nucleus, of untreated and chemotherapeutically treated breast cancer cells.

CONCLUSION

We propose that well-specified and rigorously followed protocols should be applied to immunocytochemical diagnostic techniques, especially to those related to individualized diagnosis and treatment.

Critical Appraisal of Programmed Death Ligand 1 Reflex Diagnostic Testing: Current Standards and Future Opportunities

INTRODUCTION

Patient suitability to anti-programmed death ligand 1 (PD-L1) immune checkpoint inhibition is key to the treatment of NSCLC. We present, applied to PD-L1 testing: a comprehensive cross-validation of two immunohistochemistry (IHC) clones; our descriptive experience in diagnostic reflex testing; the concordance of IHC to in situ RNA (RNA-ISH); and application of digital pathology.

METHODS

Eight hundred thirteen NSCLC tumor samples collected from 564 diagnostic samples were analyzed prospectively, and 249 diagnostic samples analyzed retrospectively in tissue microarray format. Validated methods for IHC and RNA-ISH were tested in tissue microarrays and full sections and the QuPath system were used for digital pathology analysis.

RESULTS

Antibody concordance of clones SP263 and 22C3 validation was 97% to 98% in squamous cell carcinoma and adenocarcinomas, respectively. Clinical NSCLC cases were reported as PD-L1-negative (48%), 1% to 49% (23%), and more than 50% (29%), with differences associated to tissue-type and EGFR status. Comparison of IHC and RNA-ISH was highly concordant in both subgroups. Comparison of digital assessment versus manual assessment was highly concordant. Discrepancies were mostly around the 1% clinical threshold. Challenging IHC interpretation included 1) calculating the total tumor cell denominator and the nature of PD-L1 expressing cell aggregates in cytology samples; 2) peritumoral expression of positive immune cells; 3) calculation of positive tumor percentages around clinical thresholds; and 4) relevance of the 100 malignant cell rule.

CONCLUSIONS

Sample type and EGFR status dictate differences in the expected percentage of PD-L1 expression. Analysis of PD-L1 is challenging, and interpretative guidelines are discussed. PD-L1 evaluations by RNA-ISH and digital pathology appear reliable, particularly in adenocarcinomas.

Current views on tumor mutational burden in patients with non-small cell lung cancer treated by immune checkpoint inhibitors

In the last few years, the treatment of patients with non-small cell lung cancer (NSCLC) has impressively benefitted from immunotherapy, in particular from the inhibition of immune checkpoints such as programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1). However, despite the significant survival benefit for some patients with advanced NSCLC, the objective response rates (ORRs) remain relatively low no more than 20-30% with a large proportion of patients demonstrating primary resistance. Although the selection of NSCLC patients for the first-line treatment is currently guided by the expression of PD-L1 in tumor cells as detected by immunohistochemistry, this is not the case for the second-line setting. Moreover, the sensitivity and specificity of PD-L1 expression is modest which has prompted the search for additional predictive biomarkers. In this context, the assessment of the tumor mutational burden (TMB), defined as the total number of nonsynonymous mutations in the coding regions of genes, has recently emerged as an additional powerful biomarker to select patients for immunotherapy. The purpose of our review is to highlight the recent advances as well as the challenges and perspectives in the field of TMB and immunotherapy for patients with NSCLC.

Circulating tumor cells (CTCs) for the noninvasive monitoring and personalization of non-small cell lung cancer (NSCLC) therapies

Growing evidences for tumor heterogeneity confirm that single-tumor biopsies frequently fail to reveal the widespread mutagenic profile of tumor. Repeated biopsies are in most cases unfeasible, especially in advanced cancers. We describe here how circulating tumor cells (CTCs) isolated from minimally invasive blood sample might inform us about intratumor heterogeneity, tumor evolution and treatment resistance. We also discuss the advances of CTCs research, most notably in molecularly selected non-small cell lung cancer (NSCLC) patients, highlighting challenges and opportunities related to personalized therapy.

The challenges of evaluating predictive biomarkers using small biopsy tissue samples and liquid biopsies from non-small cell lung cancer patients

The list of theranostic biomarkers for the care of patients with advanced stage or metastatic non-small cell lung cancer has lengthened considerably these last few years. Moreover, the advances in therapeutics will certainly increase the number and complexity of these tests performed in laboratories in the near future. In addition, the methods for investigation of biomarkers that require access to biological tissue are less and less invasive with the consequential increase in the use of small-sized tissue biopsies and cytological and blood samples. Thus, each laboratory must master the management of the biological samples according to the number and type of tests to be performed. This review will provide an update of the difference challenges facing pathologists and biologist in responding to the issues related to new treatments. These challenges concern: (I) the management of the pre-analytical phase; (II) the appropriate choice of the technological approach; (III) the performance of quality control; (IV) the mastering of the delay in obtaining the results; and (V) the economic model of the laboratory.

Comparison of programmed death-ligand 1 (PD-L1) immunostain for nonsmall cell lung carcinoma between paired cytological and surgical specimens

Background:

programmed death-ligand 1 (PD-L1) is a ligand for the inhibitory programmed cell death protein 1 (PD-L1), which are targeted by several anti-PD-1 and PD-L1 drugs for lung cancer treatment. In clinical practice, many lung cancer cases only have cytology samples available to test PD-L1. Our current study compared the PD-L1 immunohistochemistry (IHC) between paired cytological and surgical samples.

Materials and Methods:

Formalin-fixed lung cancer tissue microarray and paired cell blocks and surgical specimens from the same patients with a confirmed diagnosis of lung squamous cell carcinoma (SCC, n = 29) and adenocarcinoma (AC, n = 23) were sectioned for PD-L1 IHC.

Results:

PD-L1 was expressed on tumor cells in 16 of 29 (55%) SCC surgical specimens and 18 of 29 (62%) paired cytologic specimens with 83% matched immunostains. PD-L1 was expressed on tumor cells in 13 of 23 (57%) AC surgical specimens and in 17 of 23 (74%) paired cytologic specimens with 79% matched immunostains. The PD-L1 was expressed on inflammatory cells in 20 of 23 (87%) AC surgical specimens and in 15 of 23 (65%) paired cytologic specimens with 70% matched immunostains. The PD-L1 was expressed on inflammatory cells in 18 of 29 (62%) SCC surgical specimens and in 12 of 29 (41%) paired cytologic specimens with 79% matched immunostains.

Conclusions:

PD-L1 immunostain in cytology samples matched very well with paired surgical samples in both SCC and AC cases. The cytologic samples present slightly higher sensitivity for PD-L1 immunostain on tumor cells as compared to surgical biopsies.

Immunotherapy for LELC: Case Report and a Focused Review

Lymphoepithelioma-like carcinoma of the lung (LELC) is a rare, Epstein-Barr virus-associated tumor. LELC occurs mostly in young, Asian nonsmokers. A few hundred cases have been reported, mostly from retrospective Asian studies. Optimal treatment has not been clearly established. Treatment options are based on surgery for early stage and on cisplatin-based chemotherapy as first-line therapy for metastatic disease. Prognosis may seem better than for other types of non-small-cell lung cancer, but it remains poor in advanced disease, with a median survival of 24 months, and new treatments options are still warranted. Immunotherapies are now key players in the treatment of non-small-cell lung cancer. However, few data are available for this rare histologic subgroup. We have reviewed the available data on LELC with a focus on the first few cases reported with a response to a programmed cell death 1 inhibitor.

Potential predictive biomarkers in locally advanced rectal cancer treated with preoperative chemo-radiotherapy

Fluorouracil-based preoperative chemoradiotherapy represents a standard option for the treatment of locally advanced rectal cancer. Randomized clinical trials have shown that fluorouracil concomitant to preoperative radiation enhances tumor shrinkage (with 10% to 15% of the patients showing a complete pathological tumor response) compared with preoperative radiation alone. A high response rate is of clinical importance in rectal cancer, since patients who achieve a complete pathological response may experience improved long-term survival. Adding oxaliplatin to fluorouracil-based preoperative chemoradiotherapy has no effect on response of the primary rectal tumor and single-agent fluoropyrimidine remains the standard chemotherapy in this setting. Despite novel biological insights and therapeutic advances, little is known about potential biological markers able to predict pathological tumor response before treatment and to subsequently impact patients' prognosis. This review focuses on the current available data on main molecular markers and molecular subtypes and the possible upcoming introduction of such analyses in the clinical setting.

PGAM5 expression and macrophage signatures in non-small cell lung cancer associated with chronic obstructive pulmonary disease (COPD)

Background

COPD patients are at increased risk of developing non-small cell lung carcinoma that has a worse prognosis. Oxidative stress contributes to carcinogenesis and is increased in COPD patients due to mitochondrial dysfunction. We determined whether mitochondrial dysfunction is a contributing factor to the reduced survival of COPD patients with non-small cell lung carcinoma (NSCLC).

Methods

Using a transcriptomic database and outcome data of 3553 NSCLC samples, we selected mitochondrial-related genes whose levels in the tumour correlated with patient mortality. We further selected those genes showing a ≥ 2 fold expression in cancer compared to normal tissue. Cell-type specific expression of these proteins in lung tissue from NSCLC patients who were non-smokers or smokers with or without COPD (healthy smokers) was determined by immunohistochemistry. Gene set variation analysis was used in additional NSCLC datasets to determine the relative expression of specific macrophage transcriptomic signatures within lung cancer tissue.

Results

The expression of 14 mitochondrial-related genes was correlated with patient mortality and these were differentially expressed between cancer and normal lung tissue. We studied further the expression of one of these genes, PGAM5 which is a regulator of mitochondrial degradation by mitophagy. In background lung tissue, PGAM5 was only expressed in alveolar macrophages, with the highest expression in smokers with COPD compared to healthy smokers and non-smokers. In cancerous tissue, only the malignant epithelial cells and associated macrophages at the periphery of the cancer expressed PGAM5. Pre-neoplastic epithelium also showed the expression of PGAM5. There was no difference in expression in cancer tissue between COPD, healthy smoker and non-smoker groups. Macrophages at the edge of the cancer from COPD patients showed a trend towards higher expression of PGAM5 compared to those from the other groups. There was a significant correlation between PGAM5 expression in cancer tissue and the level of expression of 9 out of 49 previously-defined macrophage transcriptomic signatures with a particular one associated with patient mortality (p < 0.05).

Conclusion

PGAM5 is expressed in pre-neoplastic tissue and NSCLC, but not in normal epithelium. The association between PGAM5 expression and patient mortality may be mediated through the induction of specific macrophage phenotypes.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5140-9) contains supplementary material, which is available to authorized users.

PD-L1 and immune infiltrates are differentially expressed in distinct subgroups of gastric cancer

This study investigates the association of PD-L1 expression and immune cell infiltrates and their impact on clinical outcome, in addition to their overlap with microsatellite instability (MSI), HER2 and ATM molecular subgroups of gastric cancer (GC). PD-L1 membrane expression on tumour cells (TC) and infiltrating immune cells (IC), CD3 + T-lymphocytes, CD8+ cytotoxic T-cells, ATM and HER2 were assessed by immunohistochemistry (IHC) in the ACRG (Asian Cancer Research Group) GC cohort (N = 380). EBV status was determined using in situ hybridization and MSI status was performed using PCR and MLH1 IHC. The PD-L1 segment was associated with increased T-cell infiltrates, while the MSI-high segment was enriched for PD-L1, CD3, and CD8. Multivariate analysis confirmed PD-L1 positivity, high CD3 and high CD8 as independent prognostic factors for both disease-free survival and overall survival (all p < 0.05). Patients with MSI-high tumours had better overall survival by both univariate and multivariate analysis. The ATM-low and HER2-high subgroups differed markedly in their immune profile; the ATM-low subgroups enriched for MSI, PD-L1 positivity and CD8 + T-cells, while the HER2 segment was enriched for MSS, with no enrichment for immune markers. Hence, we demonstrate a molecular profiling approach that can divide GC into four molecular subgroups, namely ATM-low, HER2-high, PD-L1 positive and MSI-high with differing levels of immune infiltrates and prognostic significance which may help to stratify patients for response to targeted therapies.

Measuring tumor mutation burden in non-small cell lung cancer: tissue versus liquid biopsy

The introduction in the clinic of immune checkpoint inhibitors (IOs) has represented an important improvement for the treatment of patients with advanced non-small cell lung cancer (NSCLC). These drugs have shown a higher activity as compared with chemotherapy in both first- and second-line of treatment, with some patients experiencing a long-lasting response. More recently, combinations of IOs have entered clinical trials in different tumor types including NSCLC. Nevertheless, IOs are active only in a subgroup of patients and biomarkers for appropriate patients' selection are urgently needed to offer the patients an effective therapy, and also to manage the costs. Tumor mutation burden (TMB) has powerfully emerged as a potential biomarker for immunotherapy and might enter the clinic in the next months, although different challenges are still unsolved. Different methods exist to evaluate TMB in tissue, ranging from whole exome sequencing (WES) to targeted sequencing of smaller sets of genes, which need to be fully standardized to ensure that patients receive an appropriate TMB test with clear clinical interpretation. In addition, as already happened for the implementation of liquid biopsy testing from NSCLC patients to identify targetable alterations, researchers are also evaluating the possibility to calculate TMB in blood, to further enlarge the number of NSCLC patients who may benefit from immunotherapy. Preliminary data highlight the difficulty to develop targeted sequencing panels for the assessment of TMB starting from the circulating cell free DNA (cfDNA). The applicability of TMB testing on liquid biopsy needs further investigation and may be clarified within the ongoing clinical trials.

Analysis of PD-L1 expression in trophoblastic tissues and tumors

The immune checkpoint proteins, programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1), are crucial for maintaining fetomaternal immune tolerance and immune escape in cancers. In this study, we performed a comprehensive immunohistochemical study of PD-L1 expression in a large cohort of trophoblastic tissues and tumors. We found that normal villi and hydatidiform moles showed a heterogeneous PD-L1 staining among trophoblast (strong in syncytiotrophoblast, moderate in intermediate trophoblast, and weak/negative in cytotrophoblast). Eleven exaggerated placental sites (100%) showed variable PD-L1 staining, whereas 7 (36.8%) of 19 placental site nodules/plaques were weakly positive for PD-L1 (P < .001). All gestational choriocarcinomas (CCs; n = 63), epithelioid trophoblastic tumors (n = 12), and placental site trophoblastic tumors (n = 41) were PD-L1 positive, with most showing strong staining. However, PD-L1 expression was lower in epithelioid trophoblastic tumors compared with placental site trophoblastic tumors and CCs (P = .004). Three presumably germ cell-derived pure CCs, the CC elements in 13 mixed germ cell tumors, and 4 gastric/rectal CCs were also positive for PD-L1, with widespread staining. The background nontrophoblastic tissues, such as endometrial glands, squamous cells, and adenocarcinomas, were PD-L1 negative. Western blot analysis showed that PD-L1 was expressed in all 3 trophoblastic cell lines. We conclude that PD-L1 is a sensitive but nonspecific marker for trophoblast and related tumors. The frequent strong PD-L1 expression suggests that immune checkpoint blockade could be a promising approach in treating trophoblastic tumors that merits further investigation.

Immunoprofiles of colorectal cancer from Lynch syndrome

Colorectal cancers associated with Lynch syndrome are characterized by defective mismatch repair, microsatellite instability, high mutation rates, and a highly immunogenic environment. These features define a subset of cancer with a favorable prognosis and high likelihood to respond to treatment with anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) drugs. With the aim to define immune-evasive mechanisms and a potential impact hereof in colorectal cancers from Lynch syndrome versus hereditary cases with retained mismatch repair function, we immunohistochemically and transcriptionally profiled 270 tumors. Lynch syndrome-associated tumors showed an overrepresentation of tumor-infiltrating CD3, CD8 and CD68 positive cells, loss of beta-2-microglobulin (B2M) and up-regulation of PD-L1 on tumor cells. The gene expression signature of Lynch syndrome tumors was characterized by upregulation of genes related to antigen processing and presentation, apoptosis, natural killer cell-mediated cytotoxicity, and T cell activation. Tumors with loss of B2M and up-regulation of PD-L1 showed distinctive immunogenic profiles. In summary, our data demonstrate a complex tumor-host interplay where B2M loss and PD-L1 up-regulation influence immunological pathways and clinical outcome in Lynch syndrome tumors. Immunological classification may thus aid in the preselection of colorectal cancers relevant for treatment with anti-PD-1/PD-L1 therapies.