Profiles Of Tumor-infiltrating Lymphocytes Research Articles

Reduced dose fludarabine/cyclophosphamide lymphodepletion for tumor-infiltrating lymphocytes therapy (LN-144, lifileucel) in metastatic melanoma.

TPS9608 Background: Metastatic melanoma (MM) patients who have progressed following immune checkpoint inhibitors (ICI; anti–PD-1/CTLA-4 therapy) and targeted agents (BRAF/MEK inhibitors) have limited treatment options and dismal prognosis. An autologous tumor-infiltrating lymphocytes (TIL) therapy (LN-144, lifileucel) has demonstrated efficacy and durable responses in heavily pretreated advanced melanoma. In a phase II study of TIL therapy (lifileucel) with traditional lymphodepletion (LD), using fludarabine 25 mg/m2 for 5 days and cyclophosphamide (Cy) 60 mg/kg for 2 days, in 153 MM patients previously treated with ICI and BRAF/MEK inhibitors, an overall response rate (ORR) of 31% was noted, and the median duration of response (DOR) was not reached after 27.6 month follow up. We hypothesize that a reduced dose of Flu/Cy LD for TIL therapy will have similar TIL expansion and persistence post-infusion, resulting in similar efficacy with a reduced toxicity profile. Methods: Study NCT06151847 is a single-center, open-label phase II pilot trial evaluating the efficacy, in vivo persistence, and safety of TIL therapy after reduced dose Flu/Cy LD. Key inclusion criteria include unresectable or metastatic melanoma (stage IIIC-IV) with disease progression after one or more lines of therapy. Four of the 12 planned patients have been enrolled as of February 2, 2024. Central TIL manufacturing from at least a 1.5 cm tumor specimen involves ex vivo expansion through cell culture in the presence of the interleukin (IL)-2 and an anti-CD3 monoclonal antibody (1-150 x109 viable cells). Patients will receive an outpatient reduced-dose Flu/Cy LD regimen of Flu (30 mg/m2 on days -4, -3, -2, -1) and Cy (750 mg/m2 on days -4, -3, -2). Infusion of TIL will be performed on day 0 followed by high-dose IL-2 (600,000 IU/kg up to 6 doses). The primary objective will be to ascertain TIL persistence using T-cell receptor (TCR) sequencing at day 42 which will be compared to historical data already generated utilizing traditional Flu/Cy LD. The secondary objectives will be to evaluate the efficacy parameters including ORR, DOR, progression-free survival (PFS), and overall survival (OS), and the safety profile of TIL in combination with a reduced dose Flu/Cy LD regimen. Exploratory objectives will involvecorrelative analyses to characterize the immunome and microenvironment. If TIL persistence is roughly equivocal between the reduced and high-dose Flu/Cy LD regimens, the design of a larger-scale trial using reduced-dose Flu/Cy LD for TIL therapy may be considered. Study follow-up will continue for one year. Clinical trial information: NCT06151847 .

CD20highCD138low tumor-infiltrating lymphocytes predominantly related to cytokine‒cytokine receptor interactions are associated with favorable outcomes in neuroblastoma patients

Recent advances have revealed that the role of the immune system is prominent in the antitumor response. In the present study, it is aimed to provide an expression profile of tumor-infiltrating lymphocytes (TILs), including mature B cells, plasma cells, and their clinical relevance in neuroblastoma. The expression of CD20 and CD138 was analyzed in the Cangelosi786 dataset (n = 769) as a training dataset and in our cohort (n = 120) as a validation cohort. CD20 high expression was positively associated with favorable overall survival (OS) and event-free survival (EFS) (OS: P < 0.001; EFS: P < 0.001) in the training dataset, whereas CD138 high expression was associated with poor OS and EFS (OS: P < 0.001; EFS: P < 0.001) in both the training and validation datasets. Accordingly, a combined pattern of CD20 and CD138 expression was developed, whereby neuroblastoma patients with CD20highCD138low expression had a consistently favorable OS and EFS compared with those with CD20lowCD138high expression in both the training and validation cohorts (P < 0.0001 and P < 0.01, respectively). Examination of potential molecular functions revealed that signaling pathways, including cytokine‒cytokine receptor interactions, chemokine, and the NF-kappa B signaling pathways, were involved. Differentially expressed genes, such as BMP7, IL7R, BIRC3, CCR7, CXCR5, CCL21, and CCL19, predominantly play important roles in predicting the survival of neuroblastoma patients. Our study proposes that a new combination of CD20 and CD138 signatures is associated with neuroblastoma patient survival. The related signaling pathways reflect the close associations among the number of TILs, cytokine abundance and patient outcomes and provide therapeutic insights into neuroblastoma.

The Transcriptional Landscape of Immune-Response 3'-UTR Alternative Polyadenylation in Melanoma.

The prognosis of patients with malignant melanoma has been improved in recent decades due to advancements in immunotherapy. However, a considerable proportion of patients are refractory to treatment, particularly at advanced stages. This underscores the necessity of developing a new strategy to improve it. Alternative polyadenylation (APA), as a marker of crucial posttranscriptional regulation, has emerged as a major new type of epigenetic marker involved in tumorigenesis. However, the potential roles of APA in shaping the tumor microenvironment (TME) are largely unexplored. Herein, we collected two cohorts comprising melanoma patients who received immune checkpoint inhibitor (ICI) immunotherapy to quantify transcriptome-wide discrepancies in APA. We observed a global change in 3'-UTRs between responders and non-responders, which might involve DNA damage response, angiogenesis, PI3K-AKT signaling pathways, etc. Ten putative master APA regulatory factors for those APA events were detected via a network analysis. Notably, we established an immune response-related APA scoring system (IRAPAss), which exhibited a great performance of predicting immunotherapy response in multiple cohorts. Furthermore, we examined the correlation of APA with TME at the single-cell level using four single-cell immune profiles of tumor-infiltrating lymphocytes (TILs), which revealed an overall discrepancy in 3'-UTR length across diverse T cell populations, probably contributing to immunoregulation in melanoma. In conclusion, our study provides a transcriptional landscape of APA implicated in immunoregulation, which might lay the foundation for developing a new strategy for improving immunotherapy response for melanoma patients by targeting APA.

Evaluation of tumor infiltrating lymphocytes in breast carcinomas

Background: Among the parameters that have a prognostic and/or predictive significance to therapeutic response, in the case of breast carcinoma, the study of tumor-infiltrating lymphocytes in breast carcinomas is emerging. The present study aimed to access the clinicopathological profiles of tumor-infiltrating lymphocytes in patients with primary breast carcinoma. Materials and Methods: Information was collected from the archive of the Department of Pathology, about invasive breast cancers diagnosed between April 2019 –March 2020. Hormone receptor status and Ki-67 index were assessed. For tumor-infiltrating lymphocytes, hematoxylin and eosin sections were evaluated following the guidelines of the “International Working Group for tumor-infiltrating lymphocytes in Breast Cancer—2014”. Results: High tumor-infiltrating lymphocytes were seen in 64.2% and 43.8% in ages &lt; 50 and &gt; 50 respectively. All cases of invasive lobular carcinoma had low tumor-infiltrating lymphocytes. 62.5% of T1 tumors were associated with low TILs whereas 80% of low tumor-infiltrating lymphocytes were T3. 71.4% of lymph node-positive tumors had low tumor-infiltrating lymphocytes. All breast cancers showed lymphocytic infiltrate. 40% of the tumors showed intermediate to high tumor-infiltrating lymphocytes. Lymphocyte-predominant breast cancers were 30%. Among the LPBC, 55.5% were triple-negative breast cancers, 33.3% were HR+, and 11.2% were HER2 positive. Conclusions: Low tumor-infiltrating lymphocytes presented at an advanced stage of the disease at the time of diagnosis. tumor-infiltrating lymphocytes in breasts decreased with increasing age. LPBCs were predominantly TNBCs. All breast cancers were immunogenic, stating the necessity to report tumor-infiltrating lymphocytes in all breast carcinomas.

Nemvaleukin alfa, a novel engineered IL-2 fusion protein, drives antitumor immunity and inhibits tumor growth in small cell lung cancer

BackgroundSmall cell lung cancer (SCLC) is a deadly disease with a 5-year survival of less than 7%. The addition of immunotherapy to chemotherapy was recently approved as first-line treatment; however,...

LIGHT (TNFSF14) Costimulation Enhances Myeloid Cell Activation and Antitumor Immunity in the Setting of PD-1/PD-L1 and TIGIT Checkpoint Blockade.

Coinhibition of TIGIT (T cell immunoreceptor with Ig and ITIM domains) and PD-1/PD-L1 (PD-1/L1) may improve response rates compared with monotherapy PD-1/L1 blockade in checkpoint naive non-small cell lung cancer with PD-L1 expression >50%. TIGIT mAbs with an effector-competent Fc can induce myeloid cell activation, and some have demonstrated effector T cell depletion, which carries a clinical liability of unknown significance. TIGIT Ab blockade translates to antitumor activity by enabling PVR signaling through CD226 (DNAM-1), which can be directly inhibited by PD-1. Furthermore, DNAM-1 is downregulated on tumor-infiltrating lymphocytes (TILs) in advanced and checkpoint inhibition-resistant cancers. Therefore, broadening clinical responses from TIGIT blockade into PD-L1low or checkpoint inhibition-resistant tumors, may be induced by immune costimulation that operates independently from PD-1/L1 inhibition. TNFSF14 (LIGHT) was identified through genomic screens, in vitro functional analysis, and immune profiling of TILs as a TNF ligand that could provide broad immune activation. Accordingly, murine and human bifunctional fusion proteins were engineered linking the extracellular domain of TIGIT to the extracellular domain of LIGHT, yielding TIGIT-Fc-LIGHT. TIGIT competitively inhibited binding to all PVR ligands. LIGHT directly activated myeloid cells through interactions with LTβR (lymphotoxin β receptor), without the requirement for a competent Fc domain to engage Fcγ receptors. LIGHT costimulated CD8+ T and NK cells through HVEM (herpes virus entry mediator A). Importantly, HVEM was more widely expressed than DNAM-1 on T memory stem cells and TILs across a range of tumor types. Taken together, the mechanisms of TIGIT-Fc-LIGHT promoted strong antitumor activity in preclinical tumor models of primary and acquired resistance to PD-1 blockade, suggesting that immune costimulation mediated by LIGHT may broaden the clinical utility of TIGIT blockade.

Abstract 5584: Antitumor activity of liposomal formulation of eribulin combined with anti-PD-1

Abstract Eribulin (ERI) has been reported a microtubule dynamics inhibitor with unique tumor microenvironment modulations such as vascular remodeling and reversal of epithelial-mesenchymal transition activities. In the previous meeting (AACR2019), we reported that ERI has immunomodulatory activity and higher dose and frequent treatment of ERI (1.0mg/kg Q4D×3) shows combination antitumor activity with anti-PD-1. ERI-LF is a liposomal formulation of eribulin and has improved pharmacokinetics profile and improved antitumor activity compared to ERI in human xenograft models. Therefore, we expected that ERI-LF has greater immunomodulatory activity than ERI. In this study, we first compared antitumor activity of ERI-LF plus anti-PD-1 with that of ERI plus anti-PD-1 using a P-glycoprotein-knockout 4T1 (4T1#31) mouse breast cancer subcutaneous model. As a result, combination of 0.3mg/kg ERI (Q7D×2) with anti-PD-1 did not show significant stronger antitumor activity compared to each monotherapy, although it is an unfavorable condition for ERI that was treated with lower dose (0.3mg/kg) and longer interval (Q7D×2). In contrast, combination of ERI-LF (Q7D×2) with anti-PD-1 enhanced antitumor activity compared to each monotherapy in the dose range of 0.1-1.0mg/kg ERI-LF, suggesting ERI-LF has greater immunomodulatory activity than ERI. We next performed flow cytometry analysis for tumor-infiltrating lymphocytes (TILs) to reveal the mechanism of immunomodulatory activity of ERI-LF. Profile of TILs in 4T1#31 subcutaneous tumor demonstrated that 0.3mg/kg ERI-LF significantly increased the population of CD3+, CD4+, and CD8+ T cells and NK cells, and these changes were superior to that of ERI, demonstrating superior immunomodulatory activity of ERI-LF to ERI. When combined ERI-LF with anti-PD-1, the intratumoral TIL population of activated GzmB+CD8+ T and GzmB+ NK cells were significantly increased, demonstrating the mechanism of combination antitumor activity of ERI-LF with anti-PD-1. We finally verified the contribution of CD8+ T and NK cells to combination antitumor activity of ERI-LF with anti-PD-1 by using depletion antibodies for CD8+ T and NK cells. As a result, we confirmed that both CD8+ T cell singly depletion and NK cell singly depletion attenuated antitumor activity of ERI-LF plus anti-PD-1 combination. Furthermore, CD8+ T cell and NK cell combination depletion further attenuated antitumor activity of ERI-LF plus anti-PD-1 combination compared to each depletion, demonstrating that both CD8+ T and NK cells contribute antitumor activity of ERI-LF plus anti-PD-1 combination therapy. In summary, we demonstrated that ERI-LF has superior immunomodulatory activity than ERI and shows strong combination antitumor activity with anti-PD-1. Currently, Phase 1b/2 clinical trial of ERI-LF plus nivolumab in patients with selected solid cancer (NCT04078295) is underway. Citation Format: Yuki Niwa, Keito Adachi, Taro Semba. Antitumor activity of liposomal formulation of eribulin combined with anti-PD-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5584.

Profiling the Tumor-Infiltrating Lymphocytes in Gastric Cancer Reveals Its Implication in the Prognosis.

Gastric cancer is the fifth most common malignancy and the third leading cause of cancer-related mortality worldwide. Immunotherapy offers promising new treatment options for gastric cancer patients; however, it is only effective in a limited fraction of patients. In this study, we evaluated the composition of 22 tumor-infiltrating lymphocytes (TILs) in TCGA Stomach Adenocarcinoma (STAD) using deconvolution-based method by analyzing the publicly available bulk tumor RNA-seq data. The patients were classified into high-TIL and low-TIL subtypes based on their immune cell profiles and prognosis outputs. The differentially expressed genes (DEGs) between the two subtypes were identified, and GO/KEGG analysis showed that broad immune genes, such as PD-L1 and PD-1, were highly expressed in the high-TIL subtype. A comprehensive protein–protein interaction (PPI) network centered on DEGs was built, and 16 hub genes of the network were further identified. Based on the hub genes, an elastic model with 11 gene signatures (NKG7, GZMB, IL2RB, CCL5, CD8A, IDO1, MYH1, GNLY, CXCL11, GBP5 and PRF1) was developed to predict the high-TIL subtype. In summary, our findings showed that the compositions of TILs within the tumor immune microenvironment of stomach cancer patients are highly heterogeneous, and the profiles of TILs have the potential to be predictive markers of patients’ responses and overall survival outcomes.

Structure-based prediction of neoantigens paired with T cell receptors on pre-existing CD8+ tumor-infiltrating lymphocytes.

e14583 Background: Tumor neoantigens have ability to expand tumor-specific T cell immunity, which could be boosted by anti-PD-1 immunotherapy. Therapeutically relevant neoantigens should be presented on patient HLAs and recognized by tumor-reactive T cells. Despite tumor-infiltrating lymphocytes (TILs) have enriched tumor-reactive T cell populations, most tumor-specific TILs exhibit exhausted phenotype and have limitations to in vitro screening. Here, we developed in silico structure-based prediction of neoantigen discovery pipeline by pairing with T cell receptors (TCRs) on pre-existing CD8+ exhausted tumor-infiltrating lymphocytes. Methods: Tumor resections from patients with liver, stomach, colorectal, and lung cancers are subject to whole exome and transcriptome. In addition, TILs from the patients are subject to scRNA/TCRseq to select TCRs of exhausted T cells, which are mostly thought to have tumor-reactivity. Neoantigen epitopes are prioritized from our in silico pipeline including HLA binding and TCR-peptide-HLA structure-based pairing score. To evaluate the immunogenicity of selected neoantigens, the neoantigens are tested for in vitro IFNg ELISPOT assay using peripheral blood mononuclear cells (PBMCs) from the same patients, which sensitively detects antigen-experienced T cells. Results: For 5 patients with T cell-reactive neoantigens, among 23 neoantigens selected by our in silico pipeline and tested in vitro, 10 neoantigens showed positive pre-existing T cell responses by matched patients. Then, we analyzed gene expression profiles of TILs paired in silico with in vitro T cell response-positive or negative neoantigens (pTILs and nTILs, respectively) combined with TILs from 23 solid cancer patients. Interestingly, pTILs were mostly mapped to the clusters which highly expressed markers of exhaustion and cytotoxicity, while nTILs showed random distribution across all the clusters. Conclusions: Neoantigen prediction using structure-based pairing of neoantigens and phenotype-selected TILs showed promising potential to better select therapeutically-relevant cancer vaccines. This data supports further investigation of our in silico pipeline into more patient samples and preclinical studies in mouse tumor models.

Tumor-infiltrating ICOS+ Effector Regulatory T-Cells in Oral Squamous Cell Carcinoma as a Promising Biomarker for Prognosis and 'Hot' Tumor.

Tumor immunity in the tumor microenvironment is activated in patients with feasible clinical responses to immune checkpoint inhibitors. The immunological profile of tumor-infiltrating lymphocytes (TILs) obtained from patients with oral squamous cell carcinoma (OSCC) was examined in relation to their prognosis. Surface antigens, including immune checkpoint molecules, on TILs from 31 patients with primary OSCC were analyzed by flow cytometry. The activation status of TILs was examined through a heatmap analysis and unsupervised clustering classified patients into groups with activated or inactivated TILs. A supervised machine-learning algorithm for single-cell analyses in relation to prognosis was run using the Cluster Identification, Characterization, and Regression (CITRUS) program. None of surface antigens were related to prognosis. The CITRUS program revealed a relationship between CD45RA-CD4+ CD25high inducible T-cell co-stimulator (ICOS)+ TILs and recurrence, and also identified a similar fraction significantly specific to the group with activated TILs. The disease-free survival rate for patients with ≥95% ICOS+ TILs was significantly lower than that for those with <95% ICOS+ TILs. Furthermore, a review of clinicopathological factors related to prognosis identified the percentage of ICOS+ TILs to be an independent prognostic factor for patients with OSCC. CD25highICOS+ regulatory T-cells in TILs have potential as a biomarker for predicting recurrence after surgical treatment and clinical responses to immune checkpoint inhibitors in patients with OSCC.

Spatial interplay of lymphocytes and fibroblasts in estrogen receptor-positive HER2-negative breast cancer

In estrogen-receptor-positive, HER2-negative (ER+HER2−) breast cancer, higher levels of tumor infiltrating lymphocytes (TILs) are often associated with a poor prognosis and this phenomenon is still poorly understood. Fibroblasts represent one of the most frequent cells in breast cancer and harbor immunomodulatory capabilities. Here, we evaluate the molecular and clinical impact of the spatial patterns of TILs and fibroblast in ER+HER2− breast cancer. We used a deep neural network to locate and identify tumor, TILs, and fibroblasts on hematoxylin and eosin-stained slides from 179 ER+HER2− breast tumors (ICGC cohort) together with a new density estimation analysis to measure the spatial patterns. We clustered tumors based on their spatial patterns and gene set enrichment analysis was performed to study their molecular characteristics. We independently assessed the spatial patterns in a second cohort of ER+HER2− breast cancer (N = 630, METABRIC) and studied their prognostic value. The spatial integration of fibroblasts, TILs, and tumor cells leads to a new reproducible spatial classification of ER+HER2− breast cancer and is linked to inflammation, fibroblast meddling, or immunosuppression. ER+HER2− patients with high TIL did not have a significant improved overall survival (HR = 0.76, P = 0.212), except when they had received chemotherapy (HR = 0.447). A poorer survival was observed for patients with high fibroblasts that did not show a high level of TILs (HR = 1.661, P = 0.0303). Especially spatial mixing of fibroblasts and TILs was associated with a good prognosis (HR = 0.464, P = 0.013). Our findings demonstrate a reproducible pipeline for the spatial profiling of TILs and fibroblasts in ER+HER2− breast cancer and suggest that this spatial interplay holds a decisive role in their cancer-immune interactions.

CC-01 (chidamide plus celecoxib) modifies the tumor immune microenvironment and reduces tumor progression combined with immune checkpoint inhibitor

Immune checkpoint inhibitors (ICIs) have shown clinical benefit in solid tumors, with modest rates of clinical response. Hence, improved therapeutic approaches need to be investigated. Herein, we assessed a combination of chidamide plus celecoxib (called CC-01) combined with programmed cell death protein 1 (PD-1) blockade in a CT26 model as potent tumor microenvironment (TME) regulator. The antitumor activity was assessed by measuring tumor size, overall response rate, and survival rate. Immune profiling of tumor-infiltrating lymphocytes was performed by flow cytometry. Tumor tissues were assessed by chip assay to predict the possible pathway. Tumor size was significantly reduced in mice treated with CC-01 combined with or without anti-PD-1 antibody, however the triple combination therapy consistently demonstrated that it significantly increased both the ORR and survival rate in term of clinical applications. In the combination group, immune landscape profiling revealed decreased populations of immunosuppressive regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. Analysis of the mouse tumor chip data using Gene Ontology enrichment analysis of biological processes revealed that the triple combination upregulated genes associated with responses to interferon-gamma. Our results demonstrated that CC-01 possessed potent TME regulatory properties, augmenting the antitumor effect when combined with ICIs. This antitumor effect was achieved by altering the immune landscape in TILs (tumor-infiltrating lymphocytes) and was associated with immune cell activation in the TME. Furthermore, CC-01 demonstrated potent anticancer immune response activity, mainly reducing the number and function of several immunosuppressive cells. The combination of CC-01 with an ICI will further enhance the anticancer effect and boost the immune response rate. Collectively, our results support the clinical evaluation of CC-01 in combination with ICIs in several advanced cancers.

Expression of PD‑L1 and CD4+ tumor‑infiltrating lymphocytes predict survival in head and neck squamous cell carcinoma

The clinical efficacy of immune checkpoint blockade has been recently demonstrated in a variety of cancer types. The aim of the present study was to characterize the expression profile of tumor-infiltrating lymphocytes (TILs) and programmed death-ligand 1 (PD-L1) in head and neck squamous carcinoma (HNSCC). A total of 63 patients with HNSCC were enrolled in the present study. CD3+ and CD4+ TILs and the expression of PD-L1 were detected by immunohistochemistry. PD-L1 mRNA levels were evaluated by reverse transcription-quantitative PCR analysis. The association of TILs and PD-L1 with patient clinicopathological characteristics was also assessed. CD3+ and CD4+ TILs were detected in 100% of the samples. CD3+ was the predominant subset of TILs. PD-L1 was expressed in 53 of 61 (86%) patients when a score of ≥1 on tumor cells was considered positive and in 28 patients (45.2%) when a score of >5 on tumor cells was considered positive. PD-L1 mRNA levels were determined to be significantly correlated with PD-L1 protein expression. Survival analysis demonstrated that high CD4+ TILs were associated with improved overall survival (OS) and disease-free survival (DFS), and furthermore, the association of high PD-L1 expression with unfavorable OS and DFS was statistically significant. Multivariate analysis identified CD4+ TILs and PD-L1 as prognostic markers for HNSCC. The results of the present study suggested that increased CD4+ TILs in HNSCC may be associated with improved outcomes, while high expression of PD-L1 may indicate unfavorable OS and DFS; thus, these factors may serve as predictors of the response to immune checkpoint therapy.

Tumor infiltrating lymphocytes profile and response in neoadjuvant chemotherapy-treated triple-negative breast carcinoma patients.

Triple negative breast carcinoma (TNBC) has the highest mortality among all the breast carcinoma subtypes, but paradoxically, it shows the best response to neoadjuvant chemotherapy (NACT). Tumor infiltrating lymphocytes (TIL) density has been shown to have prognostic significance in TNBC. However, there are limited data on TIL subpopulation and their association with response to NACT in TNBC. The study included 80 consecutive patients with TNBC prospectively diagnosed for two and half years, who underwent tru-cut biopsy before NACT, followed by subsequent definite surgical procedures. Global TIL profile and immunohistochemistry (IHC) analysis of CD3, CD4, CD8, CD20, and CD56 were done on all baseline tru-cut biopsies and post-NACT surgical specimens. Almost half the patients were postmenopausal with a mean age of 45.89 ± 4.62 years. The majority had low CD3, low CD4, low CD56, low CD20, and high CD8 positivity in both pre- and post-NACT specimens. On multivariate analysis, low CD3, CD4, CD56 and CD 20 were established as independent predictor of poor pathologic response (PR). Low CD4 (adjusted odds ratio [OR]: 228.46) was associated with the highest OR for poor PR. Low CD8 was associated with significantly decreased odds of poor PR on univariate analysis (OR: 0.26), but it was not been established as an independent predictor of PR on multivariate logistic regression. NACT did not significantly alter the profile of TILs. TIL profile with low CD3, CD4, CD20, and CD56 expression predicts PR to NACT in TNBC and may thus help in prognostication of these patients.

Tumor-Infiltrating Lymphocytes and Their Role in Solid Tumor Progression.

Tumor-infiltrating lymphocytes (TIL) are an important component of the tumor environment. Their role in tumor growth and progression has been debated for decades. Today, emphasis has shifted to beneficial effects of TIL for the host and to therapies optimizing the benefits by reducing immune suppression in the tumor microenvironment. Evidence indicates that when TILs are present in the tumor as dense aggregates of activated immune cells, tumor prognosis and responses to therapy are favorable. Gene signatures and protein profiling of TIL at the population and single-cell levels provide clues not only about their phenotype and numbers but also about TIL potential functions in the tumor. Correlations of the TIL data with clinicopathological tumor characteristics, clinical outcome, and patients' survival indicate that TILs exert influence on the disease progression, especially in colorectal carcinomas and breast cancer. At the same time, the recognition that TIL signatures vary with time and cancer progression has initiated investigations of TIL as potential prognostic biomarkers. Multiple mechanisms are utilized by tumors to subvert the host immune system. The balance between pro- and antitumor responses of TIL largely depends on the tumor microenvironment, which is unique in each cancer patient. This balance is orchestrated by the tumor and thus is shifted toward the promotion of tumor growth. Changes occurring in TIL during tumor progression appear to serve as a measure of tumor aggressiveness and potentially provide a key to selecting therapeutic strategies and inform about prognosis.

Abstract P103: The introduction of a single strain of Bacillus into a germ-free environment did not impact the anti-PD-1 efficacy in a MC38 syngeneic model

Abstract Background. Although immunotherapy has led to exceptional and durable clinical response, the majority of patients respond poorly to the current immunotherapies. Growing evidence has linked some of the poor responsiveness to the gut microbiota, and the modulation of gut microbiome composition is becoming a promising new strategy to enhance immune checkpoint inhibitor (ICI) treatment outcome. Mouse tumor modelling under germ-free (GF) conditions combined with introduction of defined bacterial strains could be a useful approach to investigate the impact of microbiota on ICI efficacy, as well as understanding the underlying mechanisms. We previously demonstrated that GF mice exhibited a significantly poor response to anti-PD-1 therapy when compared to the specific pathogen free (SPF) mice in a subcutaneous MC38 colorectal cancer model, which is consistent with other reports. Methods. Introduction of a single strain of Bacillus in the GF-environment was assessed for its impact on the anti-mouse PD-1 monoclonal antibody (mAb) therapy in GF-mice and SPF mice, both for efficacy and pharmacodynamics tumor infiltrating lymphocytes (TILs) profiling. C57BL/6 mice were inoculated subcutaneously with MC38 tumor cells and when the tumors were reached 80-120mm3, the mice were randomized for isotype or anti-PD-1 mAb treatment. Fecal sample 16S rRNA analysis (NGS) was used to confirm the gut bacteria status. Results. The MC38 tumor in GF mice has significantly fast baseline growth kinetics, even with the introduction of Bacillus under GF conditions compared to SPF mice, suggesting tumor immunity was not enhanced by Bacillus. Despite the introduction of Bacillus, GF mice also showed reduced response to anti-PD-1 treatment when compared to the SPF mice as previously reported, further confirming that introduction of Bacillus had minimal effects on the efficacy of anti-PD-1 therapy. Moreover, the SPF mice and GF mice with Bacillus exhibited distinct profiles of TILs, consistent with distinct efficacies as observed. GF free mice showed a lower frequency of CD45+ TILs in comparison to SPF mice. In addition, GF mice exhibited lower frequency of CD8+ TILs and TIL- NKT when compared to the SPF mice, both of which are consistent with the stronger efficacy seen in SPF mice. Meanwhile, GF mice also exhibited higher granulocytic myeloid derived suppressor cells (gMDSC) and lower M1/M2 ratio, both of which imply a more suppressive tumor microenvironment in GF mice. Fecal sample analysis using 16S rRNA analysis confirmed a single strain of Bacillus was indeed introduced into the guts of all the GF mice. Conclusions. The GF conditions provide a useful environment for the investigation of specific microbiota strains on the impact on ICI treatment outcome. In summary, the introduction of Bacillus in GF mice did not impact the efficacy of anti-PD-1, thus suggesting that other strain(s) of gut microbiota in SPF mice may impact this and need to be investigated. Citation Format: Tao Yang, Bonnie Xiaobo Chen, Rongfei Lu, Xiaoyu An, Mingfa Zang, Jingjun Li, Sheng Guo, Wubin Qian, Jian Fei, Tongyang Hao, Edward Xu, Henry Li. The introduction of a single strain of Bacillus into a germ-free environment did not impact the anti-PD-1 efficacy in a MC38 syngeneic model [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P103.

64 A cloning and expression system of the neoantigen-specific TCRs from tumor-infiltrating lymphocytes by single-cell sequencing of paired TCRα and TCRβ chains

BackgroundT-cells that target tumor neoantigens arising from cancer mutations are the primary mediators of cancer immunotherapies. Identifying neoantigens and T-cells that recognize them is essential for T-cell-based immunotherapy. However, neoantigen-reactive Tumor-infiltrating lymphocytes (TILs) are highly differentiated or exhausted with a limited proliferative capacity; it is challenging to expand them for a sufficient number to probe their specificity. Therefore, we developed a novel cloning and expression system to examine TCRs discovered by single-cell sequencing of TILs for their neoantigen-specificity.MethodsTILs of lung cancer and sarcoma were analyzed. Surgically removed tumors were divided into several pieces. They were enzymatically digested to prepare fresh tumor digest (FTD) and cryopreserved. They were used to generate TIL cultures and perform WES and RNA-Seq to identify tumor-specific mutations. MHCflurry was used to predict the binding affinity of potential epitopes arising from these mutations to HLA class I. Peptides that were predicted to bind to patients‘ own MHC class I molecules strongly were then synthesized. Single TILs isolated with the ICELL8® cx system (Takara Bio) were dispensed into a nanowell TCR chip containing preprinted barcodes. Barcoded cDNAs were PCR-amplified in-chip, pooled off-chip, and used as a template in the TCR-specific PCR or for the whole transcriptome library generation of 5’ ends of all transcripts. Based on single-cell transcriptome data and TCR profiles of TILs, we predict and prioritize neoantigen-specific TCRs and cloned them into siTCR® retrovirus vectors. These TCRs were transduced into SUP-T1-based reporter cells in which ZsGreen fluorescent protein expression is controlled by AP-1 and NFAT binding sites. TCR-expressing reporter cells were cocultured with patient autologous APCs pulsed with a pool of candidate neoantigen peptides. ZsGreen expression indicates that TCRs match their cognate neoantigens.ResultsIn a lung cancer patient, we set up 18 TIL cultures and obtained 12 TILs. TILs were cocultured with FTD; IFN-γ production was measured by ELISA to evaluate their reactivity to the autologous tumor. NGS identified 197 somatic mutations, 4 fusion genes, and 8 highly expressed cancer-testis antigens. Among them, 339 candidate peptides were synthesized and screened. In addition, we cloned 3 pairs of TCRαβ chains from most expanded TIL cultures and 4 TCRs from ex vivo TILs with exhausted phenotype. Two reporter cells that express TCRs from exhausted TILs responded to the same neoantigen peptide.ConclusionsGenerating TCR expressing cell lines facilitated the identifying neoantigens and their cognate TCR sequences from patients.Ethics ApprovalG3545

Increased infiltration of regulatory T cells in hepatocellular carcinoma of patients with hepatitis B virus pre-S2 mutant

Hepatocellular carcinoma (HCC) is a frequent and deadly human cancer worldwide that is intimately associated with chronic hepatitis B virus (HBV) infection. Pre-S2 mutant is a HBV oncoprotein that plays important roles in HCC development and is linked to poor prognosis in HCC patients. However, the profiles of tumor-infiltrating lymphocytes in HCC tissues of pre-S2 mutant-positive patients remain unknown. In this study, we performed fluorescent immunohistochemistry staining to detect the infiltration of ‘anti-tumor’ cytotoxic T lymphocytes (CTLs) and ‘pro-tumor’ regulatory T cells (Tregs) in pre-S2 mutant-positive and -negative HCC patients. We showed that pre-S2 mutant-positive patients had a significantly higher infiltration of CD4+CD25+ cells and forkhead box P3 (Foxp3)-expressing cells but similar CTLs and lower granzyme B-expressing cells in HCC tissues compared with pre-S2 mutant-negative patients. Moreover, the percentage of pre-S2 plus pre-S1 + pre-S2 deletion (pre-S2 mutant) was positively correlated with the density of CD4+CD25+ cells and Foxp3-expressing cells but negatively with granzyme B-expressing cells in HCC tissues. Considering that increased intratumoral Tregs have been shown to promote tumor immune evasion, our data may provide new insights into the pathogenesis of HBV pre-S2 mutant-induced HCC and suggest that therapeutics targeting Tregs may be a promising strategy for treating pre-S2 mutant-positive high-risk patient population.

Immunotyping of tumor-infiltrating lymphocytes in triple-negative breast cancer and genetic characterization.

Tumor-infiltrating lymphocytes (TILs) reflect the host immune response against cancer cells. Immunomodulators have been recently suggested as a novel therapeutic strategy against triple-negative breast cancer (TNBC). However, the TIL profile in TNBC has not been thoroughly investigated. In the present study, the percentage, immunophenotype and genetic profiles of TILs in pre-surgical tumor samples of patients with TNBC were evaluated prior to neoadjuvant chemotherapy (NAC). Patients diagnosed with breast cancer at Hospital San José TecSalud were consecutively and prospectively enrolled in the present study between August 2011 and August 2015. The pathological response to NAC was evaluated using the de Miller-Payne and MD Anderson Cancer Center system. TIL percentage (low, intermediate, and high) was evaluated using special hematoxylin-eosin staining on the core needle biopsies. The immunophenotype of TILs was assessed by immunohistochemistry (IHC) for CD3+, CD4+ and CD8+. In addition, the gene expression profile of CD3, CD4, CD8, CD20, CD45, forkhead box P3, interleukin 6, programmed cell death 1 and CD274 molecule was assessed in all patients. A total of 26 samples from patients with TNBC prior to NAC were included in the present study. TILs were low in 30.7%, intermediate in 38.4% and elevated in 30.7% of tumors. CD3+ and CD4+ counts were associated with the pathological response to NAC (P=0.04). Finally, an overexpression pattern of CD3, CD4, CD8, CD45 and CD20 genes was observed in patients with a partial or complete pathological response. The present results demonstrated that TILs may predict the pathological response to NAC in patients with TNBC. Furthermore, a more accurate association was identified between the high expression levels of CD3, CD4, CD8, CD45 and CD20 genes and partial and complete pathological response, compared with the association between high expression and IHC alone.

Abstract 2156: IL-18 pathway agonism expands intratumoral PD1+ Tcf1+ stem-like CD8+ cells and their polyfunctional effector progeny to promote anti-tumor immunity

Abstract Recombinant cytokines were the first modern immunotherapies to produce durable cures in metastatic cancer, but their application has been hampered by only modest efficacy and limited tolerability. A major limitation to cytokine therapies is their lack of selectivity for the small fraction of lymphocytes that specifically recognize tumors. To identify cytokine pathways with greater selectively for anti-tumor lymphocytes, we analyzed single-cell RNA-seq expression data and flow cytometric profiles of tumor-infiltrating lymphocytes (TILs). Among detectable cytokine pathways, Interleukin-18 (IL-18) and its receptors IL-18R1 and IL-18RAP were markedly upregulated in activated and dysfunctional TILs, suggesting the potential of IL-18R agonism to promote anti-tumor immunity. However, recombinant IL-18 therapy has consistently failed to demonstrate anti-tumor efficacy in clinical trials. We hypothesized this may be due to the upregulation of an ultra-high affinity inhibitory decoy receptor of IL-18, IL-18BP. Indeed, IL-18BP is highly expressed in the tumor microenvironment, which we found by immunohistochemical staining and qPCR analysis of IL-18BP levels in several human cancers and syngeneic murine tumor models. Using directed evolution with yeast-surface display, we engineered “decoy-resistant” IL-18 (DR-18), a variant of IL-18 that maintains signaling potential but is impervious to binding and inhibition by IL-18BP. In multiple syngeneic tumor models including YUMMER1.7, MC38, and CT26, we found that recombinant WT IL-18 was ineffective by itself or in combination with anti-PD-1 treatment, similar to the clinical experience of rIL-18 in patients. However, in the same models, DR-18 showed robust monoagent activity that was commensurate or superior to anti-PD-1 antibodies, and it produced added therapeutic synergism when combined with anti-PD-1. Single-cell RNA-seq profiling and flow cytometry analysis of DR-18 treated tumors indicated that DR-18 treatment drives the development of poly-functional effector CD8+ T cells and NK cells. Importantly, DR-18 expands the pool of intratumoral Tcf1+ memory precursor PD1+ CD8+ T cells and decreases the prevalence of exhausted CD8+ T cells that express TOX. Mechanistically, we demonstrate that tumor antigen specific CD8+ T cells were sufficient to mediate tumor regression using LCMV epitope GP33 specific P14 CD8+ T cells in a B16-GP33 model. Together, these results highlight DR-18 is able to remodel the tumor-immune landscape to bias immune cells towards potent anti-tumor effector cells and away from the T exhausted lineage. Therefore, we conclude that the IL-18 pathway is a powerful target for immunotherapeutic intervention and implicate the secreted checkpoint IL-18BP as an obstacle to effective IL-18 immunotherapy. Citation Format: Ting Zhou, Orr-El Weizman, William Damsky, Meaghan McGeary, Marcus W. Bosenberg, Aaron M. Ring. IL-18 pathway agonism expands intratumoral PD1+ Tcf1+ stem-like CD8+ cells and their polyfunctional effector progeny to promote anti-tumor immunity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2156.