Stromal PD-L1 Research Articles

Identification of an Indoleamine 2,3-Dioxygenase 1-Based Immune Classifier for Survival Prediction of Upper Tract Urothelial Carcinoma

Background: Immunotherapy for upper tract urothelial carcinoma (UTUC) shows potential, but only a small subset of patients benefits from the treatment. This disadvantage can be attributed to additional immunosuppressive mechanisms in vivo. Indoleamine 2,3-dioxygenase 1 (IDO1) can be potentially used as an immune checkpoint target. We conducted this study to determine the prognostic role of IDO1 in UTUC and further construct an immune classifier, which can provide additional prognostic information and personalized treatment for UTUC. Methods: Two hundred and fifty-one tumor tissues of UTUC from three independent cohorts were analyzed. The expression of IDO1, programmed cell death protein 1-ligand 1 (PD-L1) and the infiltration of CD4+/CD8+/Foxp3+ T cells were evaluated using immunohistochemistry staining. Kaplan-Meier curves and Cox model were used for comparing the clinical outcomes. The Lasso Cox regression model was used to construct an IDO1-based immune classifier. Internal and external validation cohorts were included to validate the classifier. The immune contexture of different risk group stratified by the immune classifier were measured by RNA sequencing and immunofluorescence. Results: High IDO1 expression on tumor cells (TC) indicated a poorer overall survival and disease-free survival compared with low IDO1 expression in all cohorts. Patients with high expression of IDO1 TC possessed increased infiltration of Foxp3+ regulatory cells, CD8+ and CD4+ T cells. However, the distribution of IDO1 expression was irrelevant with that of PD-L1. An immune classifier based on intratumoral CD8+ lymphocytes, IDO1 TC and stromal PD-L1 expression status was developed, with its AUC values for OS at 5 years being 0.79 (95% CI 0.65-0.93) in the discovery cohort, 0.75 (95% CI 0.58-0.92) and 0.78 (95% CI 0.65-0.92) in the internal and external validation cohort, respectively. Moreover, the high-risk group stratified by our immune classifier was associated with immunosuppressive contexture, accompanied by enhanced CD8+ T cells exhaustion patterns. Conclusion: Our IDO1-based immune classifier can provide a superior accuracy for survival prediction and lead to individual stratification of UTUC immune subtypes. Funding: This study was supported by the National Natural Science Foundation of China (grant no. 81825016, 81902586); Guangdong Provincial Natural Science Foundation (grant no. 2021A1515011541); Guangdong Provincial Clinical Research Center for Urological Diseases (grant no. 2020B1111170006); Key Laboratory of Malignant Tumor Gene Regulation and Target Therapy of Guangdong Higher Education Institutes (grant no. KLB09001); Key Laboratory of Malignant Tumor Molecular Mechanism and Translational Medicine of Guangzhou Bureau of Science and Information Technology (grant no. 013-163); Key Laboratory of Tumor Immunoprevention Research of Yunnan Province (grant no. 2017DG004-04); The Health Science and Technology Talents Training and “Ten, Hundred and Thousand” Project of Kunming (grant no. 2018-sw-004); Yunnan Basic Research Program- Kunming Medical University Joint Project (grant no. 2018FE001-090). Declaration of Interest: None to declare. Ethical Approval: The study was approved by the ethics committee of Sun Yat-sen Memorial Hospital and Peking University First Hospital.

Diffuse Intratumoral Stromal Inflammation in Ovarian Clear Cell Carcinoma is Associated With Loss of Mismatch Repair Protein and High PD-L1 Expression.

Ovarian clear cell carcinoma (OCCC) is an aggressive chemotherapy-resistant cancer with limited treatment options, and some OCCCs have mismatch repair (MMR) deficiency (MMRD). Emerging evidence has revealed that various cancers with MMRD are susceptible to anti-programmed death-1/programmed death ligand-1 (anti-PD-1/PD-L1) immunotherapy, and certain histologic features are associated with MMRD. However, few studies have addressed this in OCCC. We reviewed 76 OCCCs for tumor-associated inflammation (intratumoral stromal inflammation and peritumoral lymphocytes) and performed immunohistochemistry for 4 MMR proteins and PD-L1. MMR-deficient OCCCs were analyzed for microsatellite instability (MSI), and those with MLH1 loss were tested for MLH1 promoter methylation. No patients fulfilled the Amsterdam II criteria for the diagnosis of Lynch syndrome. Four (5.3%) tumors showed diffuse intratumoral stromal inflammation obliterating the tumor-stroma interfaces, and none had peritumoral lymphoid aggregates. MMRD was found in 2 (2.6%) tumors; one had MLH1/PMS2 loss (MSI-high and MLH1 promoter methylation was detected) and the other had MSH2/MSH6 loss (MSI-low). Twenty (26.3%) tumors showed tumoral PD-L1 expression ≥1%. Both MMR-deficient tumors showed diffuse intratumoral stromal inflammation and tumoral PD-L1 expression ≥50%. Three of the 4 (75%) tumors with diffuse intratumoral stromal inflammation also showed tumoral PD-L1 expression ≥50%. None of the tumors without diffuse intratumoral stromal inflammation showed MMRD (P=0.021) or tumoral PD-L1 expression ≥50% (P=0.0001). We identified a strong correlation among diffuse intratumoral stromal inflammation, MMRD, and high tumoral PD-L1 expression in a small but significant subset of OCCCs. Histologic evaluation can facilitate patient selection for subsequent anti-PD-1/PD-L1 immunotherapy.

Immunosuppressive peculiarities of stromal cells of various kidney tumor types

Background. Renal cell carcinoma is a heterogeneous group of tumors characterized by high vascularization and immunogenicity. Immunotherapy has made a breakthrough in the treatment of this pathology, however, the lack of development of criteria for its use does not allow to achieve even greater success. It is known that the tumor stroma plays an important role in the success of immunotherapy. Among the various histological types of kidney tumors, the stroma of the clear cell renal cell carcinoma has been studied in sufficient detail. However, the remaining histological types are practically not studied. Objective: description of the immunosuppressive phenotype of the stroma of kidney tumors of various histological types. Materials and methods . The study included tumor samples obtainedfrom 44patients with renal cell carcinoma of various histological types (16 samples of chromophobe cancer, 15 samples of clear cell and 13 samples of papillary renal cell carcinoma). The method of immunohis-tochemistry evaluated the expression of tumor stromal markers, namely CD68, CD206, PU.1, CD3, IDO1 and PD-L1 in the studied samples. Results . Analysis of the total number of macrophages associated with the tumor showed that the smallest number is observed in samples of chromophobe renal cancer, while in the samples of clear cell cancer their number is greatest. A similar situation is observed for T-cells: the largest number of CD3+ cells is observed in clear cell tumors. In chromophobe and papillary tumors, their number is reduced. Papillary tumors are also characterized by an almost complete absence of expression of PD-L1 and IDO1 compared to other histological types of kidney tumors. We also showed that for PU.1 there is a strong positive correlation between its quantity and localization, as in CD68. Thus, PU.1 can be used as a general marker for describing stromal macrophages in kidney tumors. Conclusion. The study showed that kidney tumors of various histological types strongly and significantly differ in the composition of their microenvironment. These data, of course, must be considered when choosing immune therapy in the treatment of this pathology.

Identification and validation of a combined hypoxia and immune index for triple-negative breast cancer.

The interaction between hypoxia and immune status has been confirmed in various cancer settings, and corresponding treatments have been investigated. However, reliable biomarkers are needed for individual treatment, so we sought to develop a novel scoring system based on hypoxia and immune status. Prognostic hypoxia–immune status‐related signatures of patients with triple‐negative breast cancer (TNBC) were identified in The Cancer Genome Atlas (TCGA) (N = 158), Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) (N = 297), and GSE58812 (N = 107). LASSO Cox regression was used for model construction. Hypoxia and immune status expression profiles were analyzed, and infiltrating immune cells were compared. Quantitative real‐time PCR (qRT‐PCR) was used for validation in the Sun Yat‐sen University Cancer Center (SYSUCC) cohort, and immunofluorescence was applied for the detection of hypoxia and immune markers in cancer tissues. Ten cross‐cohort prognostic hypoxia–immune signatures were included to construct the comprehensive index of hypoxia and immune (CIHI) in the METABRIC cohort. Two subgroups of patients with distinct hypoxia–immune status conditions were identified using CIHI: hypoxiahigh/immunelow and hypoxialow/immunehigh, with a significantly better overall survival (OS) rate in the latter (P < 0.01). The prognostic value of CIHI was further validated in the TCGA, GSE58812, and SYSUCC cohorts (P < 0.01). Hypoxia–immune signatures were significantly differentially expressed between the two groups, and more active immune responses were observed in the hypoxialow/immunehigh group. Cytotoxic lymphocytes were inversely correlated with CIHI in silico. Differentially expressed CA‐IX and stromal PD‐L1 were detected between subgroups of the SYSUCC cohort. A hypoxia–immune‐based cross‐cohort classifier for predicting prognosis was developed and validated, which may guide hypoxia modifier treatment and immunotherapy for TNBC.

Modulation by treatment of tumor infiltrating lymphocytes (TILs) and PDL1 expression in triple-negative breast cancer in the ETNA trial.

555 Background: We assessed TILs and PDL1 expression before, during and after neoadjuvant treatment in TNBC patients enrolled in the ETNA study, and investigated associations with clinical outcome. Methods: In ETNA patients randomly received paclitaxel or nab-paclitaxel followed by 4 cycles of an anthracycline regimen, including 219 centrally confirmed TNBC. We successfully measured stromal and intratumoral TILs (sTILs, iTILs) and PDL1 status (Ventana SP142, IC≥1%) on biopsies before [n = 186/213 (84.9%)], on d1 cycle 2 (d1c2) of therapy [n = 41/186 (22.0%)], and at surgery [SX, n = 65/129 (34.9%)]. We investigated the expression and modulation over time of TILs and PDL1 and their association with pCR and event-free survival (EFS). Results: Prevalence of PDL1+ was 35.5% (baseline), 20.6% (d1c2) and 30.1% (SX). At each time-point sTILs and iTILs were higher in PDL1+ cases (p≤0.01). An effect of age of the tumor blocks (5-7.5 years) or pre-analytical issues could not be ruled out for the relatively low rate of PDL1 positivity. Paired PDL1 at baseline and d1c2 showed conversion in 25.7% (pos to neg [11.4%] or neg to pos [14.3%]). Comparing PDL1 at baseline and SX, the conversion rate was 30% (pos to neg [8.3%] or neg to pos [21.6%]). sTILs and iTILs significantly increased at cycle 2, more significantly in pCR (p≤0.001) than in RD (p≤0.05) cases, and a not significant trend of decrease was observed at surgery PDL1+ tumors had a higher pCR rate (54.7% vs 32.5%, p = 0.004). PDL1 retained significance (OR 2.00 [1.04-3.88], p = 0.039) after adjustment for sTILs (OR 1.21 [1.03-1.42], p = 0.021). High iTILs and sTILs at d1c2, but not PDL1 status, were predictive of pCR. Notably, adjusting for sTILs, PDL1+ tumors at d1c2 showed a trend for association with lower pCR rate (OR 0.06 [0.01-1.15], p = 0.062). sTILs at cycle 2 was the most informative variable (OR 1.61 [1.28-1.61], p = 0.004) and provided independent information to baseline biomarkers. Baseline PDL1 and biomarkers at cycle 2 were not associated with EFS. In surgical samples with RD, higher sTILs, but not iTILs and PDL1 status, were associated with a trend for a lower risk of recurrence (HR 0.19 [0.02-1.39], p = 0.068). Conclusions: sTILs assessment on core biopsies after one cycle of taxane is a promising early biomarker of pCR. PDL1, as well as sTILs and iTILs, provided independent prediction of pCR and were strongly modulated by treatment. The modulation of PDL1 expression should be considered whenever PDL1 is assessed in view of identifying candidates to atezolizumab in 1st line advanced setting.

The association of CD8+ T-cell infiltration and PD-L1 expression with prognosis of Chinese pulmonary large cell neuroendocrine carcinoma.

e21003 Background: Pulmonary large cell neuroendocrine carcinoma (LCNCE) is a high-grade neuroendocrine tumor with poor prognosis. The genomic profile and immune feature of LCNEC have been reported in many studies. However, the relationship between immune microenvironment and the prognosis of LCNEC patients is poorly understood. Our study was aimed to examine the infiltration of CD8+ T cell and PD-L1+ cells in LCNEC patients, and explore whether CD8+T cell and PD-L1+ cells are related to LCNEC patients’ prognosis. Methods: 37 eligible LCNEC patients (stage I-III) with received the treatment of surgical operation (27 among 37 patients underwent adjuvant radiochemotherapy) were included, tumor tissues were collected from the first medical center of Chinese PLA General Hospital. Multiplex immunohistochemistry (Multi IHC) was performed using the antibodies of CD8 and PD-L1. The univariate and multivariate cox proportional hazards analyses were used to assess the association between the abundance of CD8+T cell and PD-L1+ cells with the clinical outcome of LCNEC patients. Results: Patients were divided into high and low group using the median positive percentage of CD8 or PD-L1 as cutoff. The univariate analysis showed that patients with stromal high CD8+ T cell infiltration or stage I had significantly longer disease free survival (DFS) (CD8, p = 0.03; stage I, p = 0.036), and patients with high PD-L1 expression in stroma region, I stage, adjvant radiochemotherapy had notably increased overall survival (OS) (p = 0.049, p = 0.031, p = 0.023, respectively). However, the infiltration of CD8+ T cell or PD-L1 expression in total or tumor region had no correlation with survival of LCNEC patients. Furthermore, multivariate analysis demonstrated that low CD8+ T cell density in stroma region was an independent risk factor for PFS (p = 0.03), advanced TNM stage (II-III stage, p = 0.0009) and low stromal PD-L1 expression were independent risk factors for OS (p = 0.013). Conclusions: High infiltration of CD8+ T cell or PD-L1+ cell in stroma region were independent good prognosis factors of LCNEC patients. However, these findings need a larger LCNEC cohort to validate.

The Relationship Between Tumor-Stroma Ratio, the Immune Microenvironment, and Survival in Patients With Spinal Chordoma.

Currently, little is known about the clinical relevance of tumor-stroma ratio (TSR) in chordoma and data discussing the relationship between TSR and immune status of chordoma are lacking. To characterize TSR distribution in spinal chordoma, and investigated its correlation with clinicopathologic or immunological features of patients and outcome. TSR was assessed visually on hematoxylin and eosin-stained sections from 54 tumor specimens by 2 independent pathologists. Multiplex immunofluorescence was used to quantify the expression levels of microvessel density, Ki-67, Brachyury, and tumor as well as stromal PD-L1. Tumor immunity status including the Immunoscore and densities of tumor-infiltrating lymphocytes (TILs) subtypes were obtained from our published data and reanalyzed. Bland-Altman plot showed no difference between mean TSR derived from the two observers. TSR was positively associated with stromal PD-L1 expression, the Immunoscore and CD3+ as well as CD4+ TILs density, but negatively correlated with tumor microvessel density, Ki-67 index, surrounding muscle invasion by tumor and number of Foxp3+ and PD-1+ TILs. Low TSR independently predicted poor local recurrence-free survival and overall survival. Moreover, patients with low TSR and low Immunoscore chordoma phenotype were associated with the worst survival. More importantly, combined TSR and Immunoscore accurately reflected prognosis and enhanced the ability of TSR or Immunoscore alone for outcome prediction. These data reveal the significant impact of TSR on tumor progression and immunological response of patients. Subsequent use of agents targeting the stroma compartment may be an effective strategy to treat chordoma especially in combination with immune-based drugs.

Tumor stromal type is associated with stromal PD-L1 expression and predicts outcomes in breast cancer.

Background/AimThe aim of this study is to determine the relationship between stromal types, PD-L1 status and clinicopathological characteristics in patients with different molecular subtypes of breast cancer.Materials and methodsProtein expression levels of PD-L1 were determined by immunohistochemistry assay. Stromal type was classified based on the maturity of the tumor stroma.ResultsDifferent subtypes of breast cancer had distinct stromal types. Tumors from patients with mature stroma had lower pathological N stage and AJCC stage, more frequent high p53 expression and positive stromal PD-L1 staining. Hormone receptor negative patients had higher frequency of positive stromal PD-L1 staining. Stromal PD-L1 status was also associated with different breast cancer subtypes and EGFR expression level. Importantly, our data revealed that stromal types and stromal PD-L1 status were independent prognostic factors.ConclusionThis study highlighted the importance of stromal types and stromal PD-L1 status in determining clinical outcomes in patients with breast cancer, and suggested that stromal type classification might be readily incorporated into routine clinical risk assessment following curative resection or optimal therapeutic design.

1140P - A single-arm, open-label, multicenter, phase IIIb clinical trial with nivolumab in subjects with recurrent or metastatic platinum-refractory squamous cell carcinoma of the head and neck

1140P - A single-arm, open-label, multicenter, phase IIIb clinical trial with nivolumab in subjects with recurrent or metastatic platinum-refractory squamous cell carcinoma of the head and neck

High-Plex Predictive Marker Discovery for Melanoma Immunotherapy-Treated Patients Using Digital Spatial Profiling.

Protein expression in formalin-fixed, paraffin-embedded tissue is routinely measured by IHC or quantitative fluorescence (QIF) on a handful of markers on a single section. Digital spatial profiling (DSP) allows spatially informed simultaneous assessment of multiple biomarkers. Here we demonstrate the DSP technology using a 44-plex antibody cocktail to find protein expression that could potentially be used to predict response to immune therapy in melanoma.Experimental Design: The NanoString GeoMx DSP technology is compared with automated QIF (AQUA) for immune marker compartment-specific measurement and prognostic value in non-small cell lung cancer (NSCLC). Then we use this tool to search for novel predictive markers in a cohort of 60 patients with immunotherapy-treated melanoma on a tissue microarray using a 44-plex immune marker panel measured in three compartments (macrophage, leukocyte, and melanocyte) generating 132 quantitative variables. The spatially informed variable assessment by DSP validates by both regression and variable prognostication compared with QIF for stromal CD3, CD4, CD8, CD20, and PD-L1 in NSCLC. From the 132 variables, 11 and 15 immune markers were associated with prolonged progression-free survival (PFS) and overall survival (OS). Notably, we find PD-L1 expression in CD68-positive cells (macrophages) and not in tumor cells was a predictive marker for PFS, OS, and response. DSP technology shows high concordance with QIF and validates based on both regression and outcome assessment. Using the high-plex capacity, we found a series of expression patterns associated with outcome, including that the expression of PD-L1 in macrophages is associated with response.

The Immune Microenvironment in Hormone Receptor-Positive Breast Cancer Before and After Preoperative Chemotherapy.

Hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer is associated with low levels of stromal tumor-infiltrating lymphocytes (sTIL) and PD-L1, and demonstrates poor responses to checkpoint inhibitor therapy. Evaluating the effect of standard chemotherapy on the immune microenvironment may suggest new opportunities for immunotherapy-based approaches to treating HR+/HER2- breast tumors. HR+/HER2- breast tumors were analyzed before and after neoadjuvant chemotherapy. sTIL were assessed histologically; CD8+ cells, CD68+ cells, and PD-L1 staining were assessed immunohistochemically; whole transcriptome sequencing and panel RNA expression analysis (NanoString) were performed. Ninety-six patients were analyzed from two cohorts (n = 55, Dana-Farber cohort; n = 41, MD Anderson cohort). sTIL, CD8, and PD-L1 on tumor cells were higher in tumors with basal PAM50 intrinsic subtype. Higher levels of tissue-based lymphocyte (sTIL, CD8, PD-L1) and macrophage (CD68) markers, as well as gene expression markers of lymphocyte or macrophage phenotypes (NanoString or CIBERSORT), correlated with favorable response to neoadjuvant chemotherapy, but not with improved distant metastasis-free survival in these cohorts or a large gene expression dataset (N = 302). In paired pre-/postchemotherapy samples, sTIL and CD8+ cells were significantly decreased after treatment, whereas expression analyses (NanoString) demonstrated significant increase of multiple myeloid signatures. Single gene expression implicated increased expression of immunosuppressive (M2-like) macrophage-specific genes after chemotherapy. The immune microenvironment of HR+/HER2- tumors differs according to tumor biology. This cohort of paired pre-/postchemotherapy samples suggests a critical role for immunosuppressive macrophage expansion in residual disease. The role of macrophages in chemoresistance should be explored, and further evaluation of macrophage-targeting therapy is warranted.

Abstract 4050: Molecular characterization of residual triple-negative breast cancers after neoadjuvant chemotherapy identifies immune composition and features associated with clinical outcome

Abstract Although neoadjuvant chemotherapy (NAC) induces complete response in 30-40% of triple-negative breast cancers (TNBC), patients with residual disease at surgery have poor prognosis and limited treatment options until recurrence. Tumor-infiltrating lymphocytes (TILs) in the residual disease are a positive prognostic factor, but the composition of TILs has not been explored in granularity, and how specific immune composition of the tumor guides outcome is unclear, resulting in a lack of understanding of how to employ immunotherapies in the adjuvant setting. We assessed multiple immunologic biomarkers in a series of 100 residual TNBCs after NAC. Immune markers were assessed by multiple methods, including H&amp;E TILs analysis, standard immunohistochemistry (IHC; HLA-A, CD4, CD8, LAG-3) and multiplexed immunofluorescence (mIF; HLA-DR, GZMB, CD4, CD8, PD-L1, pan-CK). TILs and IHC were scored by clinical research pathologists and IF was scored by AQUA® analysis. Where multiple markers were multiplexed together, subset analyses was performed. Association among parameters were assessed (n=83) including clinical outcome after surgery (n=79). As previously demonstrated, TILs in residual tumors after NAC predicted both RFS and OS. H&amp;E-scored TILs were correlated to both CD4 and CD8 as scored by IHC or IF (Pearson’s r range 0.41-0.55; all p&amp;lt;0.001). CD4 and CD8 measured by IHC and IF were highly correlated (r=0.68 and 0.71, respectively; p&amp;lt;0.0001). CD4 and CD8 were also highly correlated to one another (r=0.67; p&amp;lt;0.0001). Likewise, infiltration by CD4 or CD8 were each associated with improved recurrence-free (RFS; coxPH p=0.004 and 0.007, respectively) and overall survival (OS; p=0.003 and p=0.005, respectively). Tumor and stromal PD-L1 (E1L3N) staining was associated with marginally poorer RFS (p=0.06) but not OS (p=0.94). Colocalizing GZMB and CD8 cells by mIF yielded a paradoxical finding that cytotoxic CD8 cells were associated with significantly worse RFS and OS (p=0.004 and 0.0004, respectively). In a multivariate model, total PD-L1, total CD4, and GZMB+CD8+ T cell infiltration each remained significant, suggesting independence, and provided a strongly predictive signature for RFS (p=4.6e-06). In the same analysis to predict OS, only GZMB+CD8+ T cells remained significant (p=0.0002). High GZMB+ CD8+ T cells were not associated with PD-L1 expression, but were associated with low LAG-3 expression (p=0.0009). Although the results of this study remain to be validated in larger cohorts, the paradoxical finding that GZMB+ CD8+ T cells are a negative prognostic factor for long term outcome in NAC-treated TNBC is an intriguing result. We hypothesize it may be these patients whose T cells are poised for cytotoxic activity but remain restricted through high PD-1 expression, and thus may benefit from adjuvant immunotherapy. Citation Format: Caroline Nebhan, Paula I. Gonzalez-Ericsson, Roberto Salgado, Jennifer Bordeaux, Ju Young Kim, Christine Vaupel, Henry Gomez, Justin Micah Balko. Molecular characterization of residual triple-negative breast cancers after neoadjuvant chemotherapy identifies immune composition and features associated with clinical outcome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4050.

PD-L1 expression on stromal tumor-infiltrating lymphocytes is a favorable prognostic factor in ovarian serous carcinoma

BackgroundPD-L1 expression levels determined by immunostaining are known to be related to the survival rate and prognosis of patients with various types of cancers, as well as to the therapeutic response to immune checkpoint inhibitors. Recently, the U.S. Food and Drug Administration approved an immune checkpoint inhibitor for the treatment of non-small cell lung cancer along with the clones used for PD-L1 immunostaining to predict the resulting response. In this study, we performed PD-L1 immunostaining of tissue microarrays from ovarian epithelial cancer using SP263, an approved clone, and examined the effect of PD-L1 expression on survival rate and prognosis.MethodsTissue microarrays were constructed from ovarian epithelial cancer tissues of 248 patients and PD-L1 immunostaining was performed using the SP263 clone. PD-L1 expression levels in tumor cells, intraepithelial tumor-infiltrating lymphocytes, and stromal tumor-infiltrating lymphocytes were evaluated, and the effect of PD-L1 expression on survival and prognosis was analyzed.ResultsPD-L1 was detected in tumor cells as well as intraepithelial tumor-infiltrating lymphocytes and stromal tumor-infiltrating lymphocytes. It was most frequently expressed in stromal tumor-infiltrating lymphocytes. The Kaplan-Meier curve analysis and log rank test showed that only high stromal PD-L1 expression was associated with increased overall survival in ovarian serous carcinoma. Multivariate and univariate Cox regression analyses revealed that stromal PD-L1 expression was an independent prognostic factor, especially in ovarian serous carcinoma.ConclusionsPD-L1 immunostaining using SP263 was observed in tumor cells as well as intraepithelial and stromal tumor-infiltrating lymphocytes. PD-L1-expressing stromal tumor-infiltrating lymphocytes were associated with an increased overall survival rate and may serve as a favorable prognostic factor in ovarian cancer, particularly serous carcinoma.

Quantitative assessment of immune cell populations and associations with clinical outcomes in African-American (AA) versus Caucasian triple-negative breast cancer (TNBC).

e14180 Background: Tumor infiltrating lymphocytes (TILs) are powerful prognostic and predictive factors in TNBC. We hypothesized that survival differences in TNBC by race may be caused by differences in the tumor immune microenvironment. We assessed racial differences in the extent and composition of immune infiltration in TNBC and correlated these differences with clinical characteristics and disease-free survival (DFS). Methods: Formalin fixed paraffin embedded TNBC samples and clinical information were collected for n = 43 AA and n = 43 Caucasian cases, matched by diagnosis date and stage. Stromal TILs were assessed on H&amp;E-stained slides. Multiplexed immunofluorescence was performed to quantify CD68 (macrophage), CD8 (cytotoxic T cell) and PD-L1 protein expression in the whole-section, tumor and stromal compartments. Average expression for each marker was calculated over all fields of view. Cox proportional hazards were used to assess associations between DFS, staining markers and clinical variables. Results: Characteristics of AA and Caucasian cases were not significantly different. There were 14 and 8 recurrences in the AA and Caucasian cohorts, respectively (median follow-up 8.7 vs 9.4 yrs). TIL counts (p = 0.031) and overall CD68 expression (p = 0.005) were higher in AA compared to Caucasian patients. 21% percent of AA cases had TIL predominant phenotype versus 3% of Caucasians, but CD8 expression was similar by race. PD-L1 expression was higher in stroma compared to tumor across all patients (median 401 vs 267 au, p = 0.002) and did not differ by race. Higher overall and stromal PD-L1 expression were associated with better DFS in the entire population (median 3501 vs 1895 days, p = 0.0009) and in each race separately. Higher CD68 expression was also associated with better DFS (median 3015 vs 2111 days, p = 0.0004). In multivariate analysis of DFS, stage at presentation remained significant (p = 0.002) in addition to PD-L1 and CD68 expression. Conclusions: AA TNBC had higher TIL counts and CD68 expression but similar CD8 and PD-L1 expression compared to Caucasians. High CD68 and PD-L1 expression were associated with better DFS in both race cohorts.

Abstract P2-09-12: Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC)

Abstract Background: Cytokines are being explored as a therapeutic strategy to modulate the tumor microenvironment and facilitate immunotherapy benefit in breast cancer. Here, we investigate a locoregional therapeutic approach whereby cytokines (IRX-2) are administered into the subcutaneous peri-areolar tissue (in an anatomic distribution similar to sentinel lymph node mapping) to facilitate immune cell recruitment/activation within the draining lymph nodes and tumor in ESBC. IRX-2 is derived from ex vivo phytohemagglutinin-stimulated lymphocytes and contains multiple cytokines including IL-1β, IL-2, TNF-α, IFN-γ, IL-6, IL-8, and GM-CSF, with stable concentrations from lot to lot. Preclinically, IRX-2 activates T-cells and natural killer (NK) cells, facilitates antigen presentation, and enhances activity of anti-PD-1/L1 in a SCC7 model. In a preceding head/neck squamous cell carcinoma phase I trial, perilymphatic IRX-2 was safe and increased TILs. Here, we report the final clinical results of a phase Ib trial evaluating the feasibility and immunologic activity of IRX-2 in ESBC. Methods: Beginning 21 days prior to surgical resection, enrolled operable patients with stage I-III ESBC (all subtypes) received the pre-operative IRX-2 regimen consisting of a single low-dose cyclophosphamide (300 mg/m2 to facilitate T-regulatory cell depletion), followed by 10 days of subcutaneous peri-areolar IRX-2 injections into the affected breast (1 mL × 2 at tumor axis and at 90°). Endpoints were feasibility (primary endpoint), stromal TIL (sTIL) count (pre-treatment versus post-treatment, blinded average of two pathologist reads using San Antonio H&amp;E sTIL guidelines), PD-L1 expression (Nanostring) and enumeration of peripheral immune cells by flow cytometry. Results: All patients (n=16/16) completed and tolerated the regimen with no surgical delays or treatment-attributed grade III/IV toxicities. Common adverse events (occurring in &amp;gt;15% subjects) attributed to IRX-2 injections were: injection site reaction (grade 1, n=8/16), bruising (grade 1, n=7/16), and pain (grade 1, n=3/16). Common adverse events attributed to low-dose cyclophosphamide were: fatigue (grade 1, n=5/16) and nausea (grade 1/2, n=3/16). Treatment was associated with an increase in sTIL score (Wilcoxon signed-rank p=.04), with 4/10 sTIL-low tumors (0-10% score) re-categorized to sTIL-moderate (11-50% score). Increases in PD-L1 RNA expression were observed (Wilcoxon signed-rank p=.04) in 12/16 tumors (median 57% increase, range: -53% to 185% increase), as well as increases in Nanostring NK and Th1 cell signatures. In blood, increases in CD4 and CD8 effector T-cell activation (ICOS, HLA-DR, and CD38) and T-reg depletion were observed. Conclusions: IRX-2 was well tolerated with preliminary evidence of sTIL increase, PD-L1 upregulation, and peripheral lymphocyte activation. Based upon these data and preclinical evaluations demonstrating synergy with checkpoint inhibition, the IRX-2 regimen is being evaluated for clinical efficacy in conjunction with pembrolizumab and neoadjuvant chemotherapy (doxorubicin, cyclophosphamide, paclitaxel) in patients with stage II-III triple negative breast cancer. Citation Format: Pucilowska J, Egan JE, Berinstein NL, Moxon N, Aliabadi-Wahle S, Imatani JH, Conlin A, Acheson A, Massimino K, Martel M, Campbell M, Wu Y, Sun Z, Redmond W, Shah M, Urba WJ, Page DB. Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-12.

Expression of PD-L1 in tumor-associated nerves correlates with reduced CD8+ tumor-associated lymphocytes and poor prognosis in prostate cancer.

To investigate immune profile consisting of stromal PD-L1 expression, inhibitory or non-T-cell inflamed tumor microenvironment that may predict response to anti-PD-L1/PD-1 immunotherapy in prostate cancer, we validated the specificity of a PD-L1 monoclonal antibody (E1L3N) and identified PD-L1 specific expression in prostatic stromal nerve cells. PD-L1 expression was analyzed in 73 primary prostate cancers and 7 castration-resistant prostate cancers (CRPC) by immunohistochemistry (IHC) and resulting data from primary prostate cancers were correlated with tumor-associated lymphocytes (TALs), clinicopathological characteristics and clinical outcome. PD-L1 was expressed in the tumor cells in only one primary prostate cancer case and none of the CRPC. However, PD-L1 was frequently observed in the nerve branches in the tumor-associated stroma (69 of 73 cases, 94.5%), supported by colocalization with axonal marker PGP9.5. FoxP3-, CD3- and CD8-positive T lymphocytes were observed in 74.6% (47/63), 98.4% (62/63) and 100% (61/61) of the cases, respectively. The density of PD-L1+ tumor-associated nerves (TANs) was inversely correlated with that of CD8+ TALs. Higher density of PD-L1+ TANs was significantly associated with biochemical recurrence (BCR) in Kaplan-Meier survival analysis (p = 0.016). In both univariate and multivariate Cox analysis, the density of PD-L1+ TANs was independently prognostic of BCR. In conclusion, PD-L1 expression is rare in prostate tumor cells but prevalent in TANs and negatively correlated with CD8+ TALs. Neuro-immunological interaction may be a contribution to immune-suppressive microenvironment. Combinatorial treatment regimen designs to neural PD-L1 and TALs should be warranted in future clinical application of anti-PD-L1/PD-1 immunotherapy in prostate cancer.

Correction: Stromal Cell PD-L1 Inhibits CD8+ T-cell Antitumor Immune Responses and Promotes Colon Cancer.

Correction: Stromal Cell PD-L1 Inhibits CD8+ T-cell Antitumor Immune Responses and Promotes Colon Cancer.

Stromal Cell PD-L1 Inhibits CD8+ T-cell Antitumor Immune Responses and Promotes Colon Cancer.

Stromal cells of mesenchymal origin reside below the epithelial compartment and provide structural support in the intestine. These intestinal stromal cells interact with both the epithelial cell compartments, as well as infiltrating hematopoietic immune cells. The importance of these cells in regulating immune homeostasis during inflammation is well recognized. However, little is known about their function and phenotype in the inflammatory tumor microenvironment. Using a syngeneic, immunogenic model of colorectal cancer, we showed that TNFα-initiated inflammatory signaling in CT26 colorectal cancer cells selectively induced PD-L1 expression in stromal cells. Using CD274 shRNA and antibody-mediated approaches, we showed that stromal cell PD-L1 potentiated enhanced immunosuppression, characterized by inhibition of activated CD8+ granzyme B-secreting T cells in vitro, and the inhibition of CD8+ effector cells was associated with enhanced tumor progression. Stromal cell immunosuppressive and tumor-promoting effects could be reversed with administration of anti-PD-1 in vivo We validated our findings of stromal cell CD274 expression in two cohorts of clinical samples and also observed PD-L1 induction on human stromal cells in response to exposure to the inflammatory secretome from human colon cancer cells, irrespective of microsatellite instability. Collectively, our data showed that tumor-associated stromal cells support T-cell suppression by PD-L1 induction, which is dependent on colon cancer inflammatory signaling. Our findings reveal a key role of mesenchymal stromal cells PD-L1 in suppression of CD8+ antitumor immune responses and potentiation of colorectal cancer progression. Cancer Immunol Res; 6(11); 1426-41. ©2018 AACR.

Abstract A20: Analysis of tumor infiltrating lymphocytes and expression of PD1 and PD-L1 in breast tumors prior to and after neoadjuvant chemotherapy

Abstract Introduction: The effect of chemotherapy on the presence of tumor-infiltrating lymphocytes (TILs) and expression of PD1 and PD-L1 is unclear. We sought to describe the differences in the percentage (%) of TILs, cytotoxic T lymphocytes (CTL), and expression of PD1/PD-L1 in tumors of patients (pts) with operable breast cancer (BC) treated with neoadjuvant chemotherapy (NAC) who were enrolled in a biomarker study at our institution (IRB protocol# 2010C0036). Methods: A multicolor immune-histochemical multiplex assay simultaneously detecting PD1, PD-L1, and CD8 expressing cells was performed on formalin-fixed, paraffin-embedded diagnostic pretreatment biopsy or resected tumor specimen following NAC in 18 of 26 pts participating in the study. A cut-off of ≥1% was considered positive for PD1 and PD-L1 expression. We evaluated stromal and intratumoral CTLs by estimating % of stroma and tumor that contained CD8+ cells. In addition, stromal TILs (sTILs) were identified on full-face hematoxylin and eosin stained sections and defined as the % of tumor stroma containing infiltrating lymphocytes. Pathologic complete or near-complete response (pCR) was analyzed based on residual cancer burden (RCB) score and defined as RCB class 0 or I. Analysis of all slides was performed by an expert breast pathologist. Since the number of pts was limited, we only provide descriptive statistics (mean, range). In addition, because most pts had only a biopsy or only residual tumor available for the analysis, we divided pts into 2 separate cohorts based on what tissue was available. Results: Of 18 pts, biopsy was analyzed in 7 (Bx cohort) and residual tumor was analyzed in 11 pts (RT cohort). The median age of study pts was 48 (range 32-70); 11 (61%), 6 (33%), and 1 (6%) of pts were Caucasian, African American, and Hispanic, respectively. Ten pts (5 in Bx and RT cohorts each) had triple-negative BC (TNBC), 4 had HER2+ BC (1 and 3 in Bx and RT cohorts, respectively), and 4 had hormone receptor-positive, HER2- BC (1 and 3 in Bx and RT cohorts, respectively). Eight pts (44%) had pCR. In the bx cohort, 85% of pts had pCR while 18% of pts in the RT cohort had minimal residual disease (RCB class I). In the Bx cohort, average % of sTILs was 30% (range 2-70%), including 1 pt (14%) with lymphocyte predominant tumor (≥50% of sTILs). The % of sTILs was similar in the 11 residual tumors (mean 22, range 2-60) with 2 pts having lymphocyte predominant tumors. Average % of CTLs was 19 (range 1-50) in the Bx cohort and 14 (range 1-50) in the RT cohort. An average % of intratumoral CTLs was 8 (range 1-30) and 7.5 (range 0-40) while the average % of stromal CTLs was 25 (range 1-60) and 19 (range 1-60) in the Bx and RT cohorts, respectively. Similar % and trends were seen in 10 TNBC pts. PD-L1 expression was seen in 86% and 36% of tumors in the Bx and RT cohorts, respectively, with majority of expression present in the stroma. All cases of intratumoral PD-L1 expression were also positive for stromal PD-L1 expression. This difference was also seen in the TNBC pts (80% vs. 40% of tumors were PD-L1+ in Bx and RT cohorts, respectively). An average PD-L1 intensity was approximately 3% in both cohorts (range 1-20%). Expression of PD1 was very low (1% intensity in 3 pts in Bx cohort and in 1 pt in RT cohort) and it was seen on CD8+ CTLs. Conclusion: Our study preliminarily shows that percent of sTILs and stromal and intratumoral CTLs does not differ between pretreatment biopsy and residual tumors following NAC. Lower proportion of residual tumors were PD-L1+ compared to pretreatment biopsy specimen. The study limitations include small number of subjects and lack of comparison in the same pts. Future studies are needed to confirm these findings. Citation Format: Robert Wesolowski, Zaibo Li, Christopher McQuinn, Maryam Lustberg, Bhuvaneswari Ramaswamy, Anne Noonan, Raquel Reinbolt, Sagar Sardesai, Jeffrey B. VanDeusen, Nicole Williams, William E. Carson, III. Analysis of tumor infiltrating lymphocytes and expression of PD1 and PD-L1 in breast tumors prior to and after neoadjuvant chemotherapy [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A20.

Abstract PD6-02: Immunological differences between primary and metastatic breast cancer

Abstract Background: Little is known about how the immune microenvironment of breast cancer evolves during disease progression. Immunological differences between primary and metastatic lesions may explain discordant results of clinical trials that showed low tumor response rates with immune checkpoint therapy in metastatic breast cancer but high rates of pathologic complete response in early stage disease. The goal of this project was to examine TIL counts, PD-L1 protein expression and immune gene mRNA expression in primary tumors (P) and metastatic lesions (M). Methods: FFPE blocks of primary breast cancers and core needle biopsies of matching distant metastases from 54 patients (n=104 samples). TIL count was assessed on H&amp;E slides for 39 paired tissues and is reported as % of TIL in the stroma. PD-L1 protein expression was detected with immunohistochemistry (IHC, E1L3N antibody) in 36 pairs, samples with &amp;gt; 1% cells showing staining were considered PD-L1 positive which was determined separately for tumor and stroma. The expression of 770 immune-related genes was measured using the Nanostring PanCancer Immune Gene Panel in 31 P and 17 M, including 10 paired cases. Genes were organized into 14 immune cell type (total T, Th1, Treg, Total CD8, exhausted CD8, Cytotoxic T, B, NK, NK-CD56, Mast cell, CD45, Dendritic cell, macrophage, neutrophil) and 22 immune function metagenes. Differences in mean expression in P and M were assessed using Fisher exact and Mann-Whitney tests without adjustment for multiple comparisons due to overlap in metagene membership. Results: Mean TIL counts (14% vs 20%, p=0.026) and stromal PD-L1 positivity by IHC (14% vs 54%, p=0.004) were significantly lower in M. PD-L1 positivity in tumor cells was similar (25% in M vs 42%, in P p=0.14). The total TIL gene expression score (2.48 vs 2.8 p=0.018) and all immune cell type metagenes, except neutrophils, had lower absolute expression levels in M. The relative abundance of neutrophils (0.035 vs -0.38, p=0.0001) and macrophages (0.62 vs 0.38 p=0.0013) increased in M. Among the 22 immune function metagenes, T, B and NK cell functions, cytotoxicity, chemokine and TNF superfamily expression, regulation and pathogen defense were significantly lower in M and none showed significantly increased expression in M. Pro-inflammatory/immune-activating cytokines of IL-6, CCL-5,-12,-19,-22 and CXCL-5,-9,-10,-11 were all significantly lower in M. The greatest drop was seen for CXCL-9 (2243 vs 422, p&amp;lt;0.0001) and CCL-19 (2537 vs 309, p&amp;lt;0.0001). No cytokine showed increased expression in M. Only 6 immune genes (C7, GPI, MAPK1, TAB1, TLR5, PVR) showed significantly higher (p&amp;lt;0.05) expression in M, the greatest increase was for Complement C7 (member of the terminal complement pathway membrane attack complex; 484 vs 3499, p=0.03) and GPI (glucose 6-phosphate isomerase that induces immunoglobulin secretion; 1967 vs 3011, p=0.01). Conclusions: Breast cancer metastases exist in an attenuated immune microenvironment. Most immune cell subtypes, immune functions, and immune-associated gene expression are lower in M compared to P, consistent with immune escape. Metastatic lesions have higher relative abundance of macrophages and neutrophils, which suggest new therapeutic opportunities. Citation Format: Szekely B, Bossuyt V, Li X, Baine M, Silber A, Sanft T, Hofstatter E, Mougalian S, Baghwagar S, Neumeister V, Pelekanou V, Hatzis C, Pusztai L. Immunological differences between primary and metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD6-02.