PD-L1 Overexpression Research Articles

Immune checkpoint inhibitors in luminal gastrointestinal malignancies: going beyond MSI-H/dMMR, TMBand PD-L1.

In luminal gastrointestinal tumors, immune checkpoint inhibitors (ICIs) targeting PD-1, PD-L1and CTLA-4 have been investigated in multiple settings. The indications for these drugs are primarily dependent on specific biomarkers that imply immunogenicity: overexpression of PD-L1, tumor mutational burden, loss of mismatch repair proteins (dMMR) and/or highmicrosatellite instabilitystatus. Although these markers can be both predictive and prognostic, there is variability in how they are measured and used to guide therapies. Moreover, the use of ICIs can be further refined with a better understanding of the tumor microenvironment and interactions with other available therapies. The purpose of this review is to characterize luminal gastrointestinal tumors'responses to ICIs considering known predictive biomarkers and discuss emerging therapeutic approaches using ICIs.

Molecular mechanism of lncRNA SNHG12 in immune escape of non-small cell lung cancer through the HuR/PD-L1/USP8 axis

BackgroundThe pivotal role of long noncoding RNAs (lncRNAs) in cancer immune responses has been well established. This study was conducted with the aim of exploring the molecular mechanism of lncRNA small nucleolar RNA host gene 12 (SNHG12) in immune escape of non-small cell lung cancer (NSCLC).MethodsExpression of lncRNA SNHG12, programmed cell death receptor ligand 1 (PD-L1), ubiquitin-specific protease 8 (USP8), and human antigen R (HuR) in NSCLC tissues and cells was measured, and their binding relationship was determined. NSCLC cell proliferation and apoptosis were assessed. Peripheral blood mononuclear cells (PBMCs) were co-cultured with NSCLC cells. The ratio of CD8+ T cells, PBMC proliferation, and inflammatory factors were determined. lncRNA SNHG12 localization was assessed via subcellular fractionation assay. The half-life period of mRNA was determined using actinomycin D. Xenograft tumor models were established to confirm the role of lncRNA SNHG12 in vivo.ResultsLncRNA SNHG12 was found to be prominently expressed in NSCLC tissues and cells, which was associated with a poor prognosis. Silencing lncRNA SNHG12 resulted in the reduction in proliferation and the promotion of apoptosis of NSCLC cells, while simultaneously increasing PBMC proliferation and the ratio of CD8+ T cells. Mechanically, the binding of lncRNA SNHG12 to HuR improved mRNA stability and expression of PD-L1 and USP8, and USP8-mediated deubiquitination stabilized the protein level of PD-L1. Overexpression of USP8 or PD-L1 weakened the inhibition of silencing lncRNA SNHG12 on the immune escape of NSCLC. Silencing lncRNA SNHG12 restricted tumor growth and upregulated the ratio of CD8+ T cells by decreasing USP8 and PD-L1.ConclusionLncRNA SNHG12 facilitated the immune escape of NSCLC by binding to HuR and increasing PD-L1 and USP8 levels.

PD-L1 is overexpressed on tumorspheres cultured from circulating cancer stem cells in patients with breast cancer.

3052 Background: Circulating cancer cells, and in particular their very rare subpopulation, circulating cancer stem cells (cCSCs), are responsible for recurrence and metastasis. The exact role of cCSCs in escape of cancer from immunosurveillance is still unknown, but recent studies revealed that enhanced PDL-1 expression in cancer stem cells is linked to immune evasion and could crucially contribute to the maintenance of CSC self-renewal. Understanding the mechanisms behind this PDL-1 overexpression in cancer stem cells is critical for developing more effective anti-PD-1/PD-L1 therapy. Therefore the aim of the study was to determine the number of tumorspheres and expression of PD-L1 on tumorspheres cultured from cCSC in breast cancer patients. Methods: 110 patients with breast cancer in different stages of disease were included in this study. The determination of circulating cancer stem cells was performed using the sphere-forming assay. Additionally anti-PDL-1 antibody staining was applied to examine PDL-1 expression on breast tumorspheres. Results: We have developed an innovative in vitro platform for detection of cCSCs from peripheral blood of cancer patients. The number of tumorspheres increased significantly with tumor progression and aggressiveness of primary tumor. Patients with metastatic disease had statistically more tumorspheres as compared to patients without metastasis (30 vs 10/100µl blood, p < 0.05). Patients with multiple metastasis had more tumorspheres compared to patients with single metastases (60 vs 30/100µl blood, p < 0.05). The number of tumorspheres was positively correlated with Ki-67, Her2 status and grade score in primary breast tumors. We observed high PDL-1 expression and their considerable heterogeneity in enriched tumorspheres. Conclusions: The number of tumorspheres cultured from peripheral blood directly reflects aggressiveness and proliferation capacity of primary tumor. The presence of tumorspheres with expression of PDL-1 might suggest their immunregulatory potential. Better understanding of the interaction between cCSCs and tumor immunology may help to identify strategies to eradicate the minor subpopulation that escapes conventional therapy attack, thus providing a solution to the problem of drug resistance and metastasis.

KEYNOTE B68: Open-label phase 2 study of the efficacy and safety of pembrolizumab administered every six weeks in patients with relapsed or refractory classical Hodgkin lymphoma or primary mediastinal B-cell lymphoma.

TPS7585 Background: Classical Hodgkin lymphoma (cHL) and primary mediastinal B-cell lymphoma (PMBCL) frequently harbor amplifications at 9p24.1, leading to overexpression of PD-L1 and PD-L2, suggesting a genetically driven vulnerability to programmed death 1 (PD-1) blockade. The PD-1 inhibitor pembrolizumab, dosed at 200 mg every 3 weeks (Q3W), demonstrated strong antitumor activity and acceptable safety that led to approvals for adult and pediatric patients with relapsed or refractory (R/R) cHL and R/R PMBCL. Efficacy, safety, and pharmacokinetic (PK) results from studies in solid tumors have since led to accelerated approval for the pembrolizumab 400 mg Q6W regimen for all indications in adults; however, further efficacy and safety data are needed for hematologic indications. The open-label, single-arm, multisite, global, phase 2 KEYNOTE-B68 study (NCT04875195) evaluates the safety, efficacy, and PK profile of pembrolizumab 400 mg Q6W in patients with R/R cHL or PMBCL. Methods: Patients must have histologically confirmed R/R cHL (cohort 1) or R/R PMBCL (cohort 2) per WHO classification and radiographically measurable disease per the Lugano 2014 classification criteria and must not have previously received treatment with anti–PD-1 therapy. Eligible patients must have failed to respond to or relapsed after receiving an autologous stem cell transplant (ASCT) or must be ineligible for ASCT and must have failed to respond or relapsed after ≥1 (cHL) or ≥2 (PMBCL) prior lines of therapy; patients with PMBCL must have received ≥1 line of therapy containing rituximab. Approximately 60 patients will be enrolled. They will receive pembrolizumab 400 mg IV Q6W for up to 18 cycles. Disease assessments will occur Q12W by investigator per the Lugano 2014 response criteria. Local radiographic assessments will be collected by computed tomography Q12W and by positron emission tomography at weeks 12 and 24 and to confirm complete response. Adverse events will be monitored and assessed by investigators throughout the study, and their severity will be graded per NCI Common Terminology Criteria for Adverse Events, version 5.0 guidelines. Patients who receive an allogeneic SCT within 2 years of the last dose of study treatment will be monitored for 18 months after SCT for events of clinical interest. The primary end point (assessed per cohort) is objective response rate by investigator per the Lugano 2014 classification criteria. Secondary end points (assessed per cohort) include duration of response by investigator assessment, characterization of the PK profile and immunogenicity for pembrolizumab 400 mg Q6W, and safety. Exploratory end points assessed per cohort include overall survival, progression-free survival per the Lugano 2014 criteria, and molecular biomarker analyses. Clinical trial information: NCT04875195.

Enhancing PD-L1 Degradation by ITCH during MAPK Inhibitor Therapy Suppresses Acquired Resistance.

MAPKi induces tumor cell-surface PD-L1 accumulation, which promotes immune evasion and therapy resistance. ITCH degrades PD-L1, optimizing antitumor T-cell immunity. We propose degrading tumor cell-surface PD-L1 and/or activating tumor-intrinsic ITCH as strategies to overcome MAPKi resistance. This article is highlighted in the In This Issue feature, p. 1825.

Human papilloma virus integration sites and genomic signatures in head and neck squamous cell carcinoma.

A prevalence of around 26% of human papillomavirus (HPV) in head and neck squamous cell carcinoma (HNSCC) has been previously reported. HPV induced oncogenesis mainly involving E6 and E7 viral oncoproteins. In some cases, HPV viral DNA has been detected to integrate with the host genome and possibly contributes to carcinogenesis by affecting the gene expression. We retrospectively assessed HPV integration sites and signatures in 80 HPV positive patients with HNSCC, by using a double capture‐HPV method followed by next‐generation Sequencing. We detected HPV16 in 90% of the analyzed cohort and confirmed five previously described mechanistic signatures of HPV integration [episomal (EPI), integrated in a truncated form revealing two HPV‐chromosomal junctions colinear (2J‐COL) or nonlinear (2J‐NL), multiple hybrid junctions clustering in a single chromosomal region (MJ‐CL) or scattered over different chromosomal regions (MJ‐SC) of the human genome]. Our results suggested that HPV remained episomal in 38.8% of the cases or was integrated/mixed in the remaining 61.2% of patients with HNSCC. We showed a lack of association of HPV genomic signatures to tumour and patient characteristics, as well as patient survival. Similar to other HPV associated cancers, low HPV copy number was associated with worse prognosis. We identified 267 HPV‐human junctions scattered on most chromosomes. Remarkably, we observed four recurrent integration regions: PDL1/PDL2/PLGRKT (8.2%), MYC/PVT1 (6.1%), MACROD2 (4.1%) and KLF5/KLF12 regions (4.1%). We detected the overexpression of PDL1 and MYC upon integration by gene expression analysis. In conclusion, we identified recurrent targeting of several cancer genes such as PDL1 and MYC upon HPV integration, suggesting a role of altered gene expression by HPV integration during HNSCC carcinogenesis.

Restored CD8+PD-1+ T Cells Facilitate the Response to Anti-PD-1 for Patients With Pancreatic Ductal Adenocarcinoma.

PurposeWe aimed to investigate the restoration of CD8+PD-1+ T cells through adoptive T-cell therapy (ACT) in relation to the prognosis and the therapeutic response to anti-PD-1 in patients with advanced pancreatic cancer (APC).MethodsA total of 177 adult patients who underwent tumor resection as initial treatment for pancreatic ductal adenocarcinoma (PDAC) from February 2013 to July 2019 at Zhongnan Hospital of Wuhan University were enrolled in this study. Another cohort of 32 patients with APC was prospectively enrolled from Capital Medical University Cancer Center between June 1, 2013, and May 30, 2019.ResultsOf the 177 patients who received tumor resection, 67 tumor samples showed overexpression of PD-L1 and 110 patients with low expression of PD-L1. We found that overexpressed PD-L1 was a significant prognostic factor related to overall survival (OS). Furthermore, we tested the percentage of peripheral CD8+PD-1+ T cells in all patients and found that it was significantly correlated with the PD-L1 expression and the prognosis of patients with PDAC. The peripheral blood T lymphocyte subtypes were tracked for 30 months, and CD8+PD-1+ cells were shown to decrease. After that, we performed ACT for patients with APC in another cancer center. We found that the ratios of posttreatment of ACT/pre-ACT CD8+PD-1+ T cells were significantly related to the prognosis of patients with APC. Moreover, patients with combined treatment of ACT with anti-PD-1 had significantly favorable OS.ConclusionsThis study showed that the CD8+PD-1+ T-cell level was related to the expression of PD-L1. Restoring CD8+PD-1+ T cells in patients with APC by treatment of ACT significantly benefits the prognosis and facilitates the response to anti-PD-1.

Overexpression of PD-L1 causes germ cells to slough from mouse seminiferous tubules via the PD-L1/PD-L1 interaction.

Spermatogenesis is a cyclical process in which different generations of spermatids undergo a series of developmental steps at a fixed time and finally produce spermatids. Here, we report that overexpression of PD‐L1 (B7 homolog1) in the testis causes sperm developmental disorders and infertility in male mice, with severe malformation and sloughing during spermatid development, characterized by disorganized and collapsed seminiferous epithelium structure. PD‐L1 needs to be simultaneously expressed on Sertoli cells and spermatogonia to cause spermatogenesis failure. After that, we excluded the influence of factors such as the PD‐L1 receptor and humoral regulation, confirming that PD‐L1 has an intrinsic function to interact with PD‐L1. Studies have shown that PD‐L1 not only serves as a ligand but also plays a receptor‐like role in signal transduction. PD‐L1 interacts with PD‐L1 to affect the adhesive function of germ cells, causing malformation and spermatid sloughing. Taken together, these results indicate that PD‐L1 can interact with PD‐L1 to cause germ cell detachment and male infertility.

Immunosuppressive niche engineering at the onset of human colorectal cancer

The evolutionary dynamics of tumor initiation remain undetermined, and the interplay between neoplastic cells and the immune system is hypothesized to be critical in transformation. Colorectal cancer (CRC) presents a unique opportunity to study the transition to malignancy as pre-cancers (adenomas) and early-stage cancers are frequently resected. Here, we examine tumor-immune eco-evolutionary dynamics from pre-cancer to carcinoma using a computational model, ecological analysis of digital pathology data, and neoantigen prediction in 62 patient samples. Modeling predicted recruitment of immunosuppressive cells would be the most common driver of transformation. As predicted, ecological analysis reveals that progressed adenomas co-localized with immunosuppressive cells and cytokines, while benign adenomas co-localized with a mixed immune response. Carcinomas converge to a common immune “cold” ecology, relaxing selection against immunogenicity and high neoantigen burdens, with little evidence for PD-L1 overexpression driving tumor initiation. These findings suggest re-engineering the immunosuppressive niche may prove an effective immunotherapy in CRC.

Genetic characteristics involving the PD-1/PD-L1/L2 and CD73/A2aR axes and the immunosuppressive microenvironment in DLBCL

BackgroundTargeting the PD-1/PD-L1/L2 (programmed cell death protein 1/programmed cell death ligand 1/ligand 2) pathway combined with other immunosuppressive signalings, such as CD73/A2aR (A2a adenosine receptor) adenosine signaling, has emerged as...

Tumor-derived PD1 and PD-L1 could promote hepatocellular carcinoma growth through autophagy induction in vitro

BackgroundsAutophagy in tumor was also found to influence immune microenvironment. The relation between autophagy and cancer intrinsic PD1 and PD-L1 expression was not clear. MethodsWith data from TCGA and GTEx databases, mRNA expression levels of autophagy-related genes were compared between tumor samples and normal tissues, which were also correlated with survival status. Expression of autophagy-related genes were also associated with clinical traits in datasets of GSE14520 and ICGC LIRI. Single sample gene set enrichment analysis (ssGSEA) was used to calculate autophagy scores in tumor samples, using signatures from MSigDB database. Lentivirus (PD1 and PD-L1), siRNA (ATG13) and plasmids (LC3A/B) were used to target specific genes in tumor cells; Western blot was used to examine protein expression accordingly. Co-immunoprecipitation was performed to find PD1 or PD-L1 interacting proteins; colony formation and EdU analysis were used to evaluate tumor cell growth abilities. ResultsmRNA levels of autophagy markers were increased in tumor and correlated with worse survival of cancer patients. In hepatocellular carcinoma (HCC), high mRNA expression of autophagy markers was related to poor clinical status; increasing LC3 expression in HCC cell lines could promote tumor growth. Tumor intrinsic PD1 or PD-L1 were related to higher autophagy levels in specific tumor types; over-expression of PD1 or PD-L1 could increase autophagy in tumor cells through ATG13 interaction. ConclusionAutophagy could promote tumor growth in specific cancer types. Tumor intrinsic PD1 or PD-L1 could both increase autophagy through ATG13 interaction.

Expression Profile of Selected Antitumor Immune Response Genes in Pediatric Classic Hodgkin Lymphoma.

Classic Hodgkin lymphoma (cHL) is one of the most common pediatric solid tumors and is responsible for cancer-related deaths in children. Therefore, to modulate the active antitumor T-cell immune response in cHL can be a treatment strategy. In the present study, we aimed to investigate the expression profiles of selected antitumor immune response genes in pediatric cHL and their relationships with clinical and prognostic parameters to determine their significance in precision medicine. Thirty-nine pediatric nodal cHL patients were enrolled in the study. We analyzed mRNA expression of selected immune response regulatory genes such as PD-L1, CSF2, CTLA4, CXCL5, IDO1, CXCL8, MIF, NOS2, PDCD1, PTGS2, and TGFβ1 using real-time quantitative polymerase chain reaction. Only PD-L1 overexpression was statistically related to bulky disease, advanced tumor stage, and high-risk disease category and seen significantly in Epstein-Barr virus-negative pediatric cHL. No expression profiles were correlated with relapse or survival. We conclude that PD-L1 overexpression in pediatric cHL cases is a strong predictor of high-risk categorization. In addition to being a prognostic biomarker, PD-L1 blockade is also a druggable marker for the targeted therapy in Epstein-Barr virus-negative pediatric Hodgkin lymphoma.

Recombinant human interleukin-7 reverses T cell exhaustion ex vivo in critically ill COVID-19 patients

BackgroundLymphopenia is a hallmark of severe coronavirus disease 19 (COVID-19). Similar alterations have been described in bacterial sepsis and therapeutic strategies targeting T cell function such as recombinant human interleukin 7 (rhIL-7) have been proposed in this clinical context. As COVID-19 is a viral sepsis, the objectives of this study were to characterize T lymphocyte response over time in severe COVID-19 patients and to assess the effect of ex vivo administration of rhIL-7.ResultsPeripheral blood mononuclear cells from COVID-19 patients hospitalized in intensive care unit (ICU) were collected at admission and after 20 days. Transcriptomic profile was evaluated through NanoString technology. Inhibitory immune checkpoints expressions were determined by flow cytometry. T lymphocyte proliferation and IFN-γ production were evaluated after ex vivo stimulation in the presence or not of rhIL-7. COVID-19 ICU patients were markedly lymphopenic at admission. Mononuclear cells presented with inhibited transcriptomic profile prevalently with impaired T cell activation pathways. CD4 + and CD8 + T cells presented with over-expression of co-inhibitory molecules PD-1, PD-L1, CTLA-4 and TIM-3. CD4 + and CD8 + T cell proliferation and IFN-γ production were markedly altered in samples collected at ICU admission. These alterations, characteristic of a T cell exhaustion state, were more pronounced at ICU admission and alleviated over time. Treatment with rhIL-7 ex vivo significantly improved both T cell proliferation and IFN-γ production in cells from COVID-19 patients.ConclusionsSevere COVID-19 patients present with features of profound T cell exhaustion upon ICU admission which can be reversed ex vivo by rhIL-7. These results reinforce our understanding of severe COVID-19 pathophysiology and opens novel therapeutic avenues to treat such critically ill patients based of immunomodulation approaches. Defining the appropriate timing for initiating such immune-adjuvant therapy in clinical setting and the pertinent markers for a careful selection of patients are now warranted to confirm the ex vivo results described so far.Trial registration ClinicalTrials.gov identifier: NCT04392401 Registered 18 May 2020, http:// clinicaltrials.gov/ct2/show/NCT04392401.

20P Immuno-modulating effects of hyperthermia on PD-L1 and NLRC5 in ovarian cancer

Hyperthermia (HT) has been widely used as an adjuvant to chemotherapy in the treatment of ovarian cancer, it has pleiotropic effects on cellular processes involved in tumor growth and progression. Inducing cellular stress response through heat-shock proteins (HSPs) expression is one of the main hallmarks of HT. HSPs have been reported to trigger an immune activation. However, antitumor immune responses are often invalidated by immune evasion mechanisms such as the overexpression of the immunosuppressive PD-L1 and the loss of MHC class I expression.

Co-Expression and Combined Prognostic Value of CSPG4 and PDL1 in TP53-Aberrant Triple-Negative Breast Cancer.

BackgroundIn triple-negative breast cancer (TNBC), PDL1/PD1-directed immunotherapy is effective in less than 20% of patients. In our preliminary study, we have found CSPG4 to be highly expressed together with PDL1 in TNBCs, particularly those harboring TP53 aberrations. However, the clinical implications of co-expressed CSPG4 and PDL1 in TNBCs remain elusive.MethodsA total of 85 advanced TNBC patients treated in the Hunan Cancer Hospital between January 2017 and August 2019 were recruited. The expressions of CSPG4 and PDL1 in TNBC tissues were investigated using immunohistochemistry (IHC). The RNA-seq dataset from the TCGA-BRCA project was further used to analyze the mRNA expression of CSPG4 and PDL1 in TP53-aberrant TNBCs. Cox proportional hazards model and Kaplan–Meier curves with Logrank test was used to analyze the effects of CSPG4 and PDL1 on survival. TNBC cell lines were further used to investigate the molecular mechanism that were involved.Results TP53 aberrations occurred in more than 50% of metastatic TNBCs and were related to higher tumor mutation burden (TMB). In TCGA-BRCA RNA-seq dataset analysis, both CSPG4 and PDL1 levels were high in TNBCs, especially in TP53-aberrant TNBCs. IHC assay showed nearly 60% of advanced TNBCs to be CSPG4-positive and about 25% to be both CSPG4-positive and PDL1-positive. The levels of CSPG4 and PDL1 were high in TNBC cell lines as revealed by flow cytometry and immunoblotting compared with non-TNBC cells. Univariate Cox regression analysis indicated that CSPG4 positivity was a significant risk factor for progression-free survival in metastatic TNBCs, with a hazard ratio (HR) of 2.26 (P = 0.05). KM curves with Logrank test also identified high level of CSPG4 as a significant risk factor for overall survival in advanced breast cancers in TCGA-BRCA samples (P = 0.02). The immunoblotting assays showed that EMT-related pathways were involved in CSPG4-mediated invasion.ConclusionsCSPG4 expression level is associated with PDL1 positivity in TP53-aberrant TNBC cells. Patients with CSPG4 expression have poor treatment response and poor overall survival. Co-expressed CSPG4 and PDL1 may have an important prognostic value and provide new therapeutic targets in TNBC patients. CSPG4 might mediate tumor invasion and PDL1 overexpression through EMT-related pathway.

RelB upregulates PD-L1 and exacerbates prostate cancer immune evasion

BackgroundThe interaction between programmed death receptor (PD-1) and its ligand (PD-L1) is essential for suppressing activated T-lymphocytes. However, the precise mechanisms underlying PD-L1 overexpression in tumours have yet to be fully elucidated. Here, we describe that RelB participates in the immune evasion of prostate cancer (PCa) via cis/trans transcriptional upregulation of PD-L1.MethodsBased on transcriptome results, RelB was manipulated in multiple human and murine PCa cell lines. Activated CD4+ and CD8+ T cells were cocultured with PCa cells with different levels of RelB to examine the effect of tumourous RelB on T cell immunity. Male mice were injected with murine PCa cells to validate the effect of RelB on the PD-1/PD-L1-mediated immune checkpoint using both tumour growth and metastatic experimental models.ResultsPD-L1 is uniquely expressed at a high level in PCa with high constitutive RelB and correlates with the patients’ Gleason scores. Indeed, a high level of PD-L1 is associated with RelB nuclear translocation in AR-negative aggressive PCa cells. Conversely, the silencing of RelB in advanced PCa cells resulted in reduced PD-L1 expression and enhanced susceptibility of PCa cells to the T cell immune response in vitro and in vivo. Mechanistically, a proximal NF-κB enhancer element was identified in the core promoter region of the human CD274 gene, which is responsible for RelB-mediated PD-L1 transcriptional activation. This finding provides an informative insight into immune checkpoint blockade by administering RelB within the tumour microenvironment.ConclusionThis study deciphers the molecular mechanism by which tumourous RelB contributes to immune evasion by inhibiting T cell immunity via the amplification of the PD-L1/PD-1-mediated immune checkpoint.

Abstract P4-04-08: Determination of PD-L1 expression on tumorspheres cultured from the peripheral blood in patients with breast cancer

Abstract Background Cancer stem cells (CSCs) are the critical subpopulation of cancer cells involved in tumor formation, progression, metastasis and drug resistance. CSCs also have been considered as the main cause of cancer recurrence. The exact role of CSCs in escape of cancer from immunosurveillance is still unknown, but recent studies revealed that enhanced PDL-1 expression in cancer stem cells is linked to immune evasion and could crucially contribute to the maintenance of CSC self-renewal. Understanding the mechanisms behind this PDL-1 overexpression in cancer stem cells is critical for developing more effective anti-PD-1/PD-L1 therapy. Therefore the aim of the study was to determine the number of tumorspheres and expression of PD-L1 on tumorspheres cultured from the peripheral blood in patients with breast cancer.Methods:110 patients with breast cancer in different stages of disease were included in this study. The determination of circulating tumor cells and circulating cancer stem cells (cCSC) was performed using maintrac and tumorsphere forming assay, respectively. Additionally anti-PDL-1 antibody staining was applied to examine PDL-1 expression on breast tumorspheres.Results:We developed an innovative in vitro platform for cultivation of CSCs from peripheral blood of solid cancer patients and confirmed for the first time that tumorspheres are positive for PDL-1 in breast cancer patients. Our data also show a considerable heterogeneity in the PDL-1 expression of tumorspheres. We confirmed once again that the number of tumorspheres increased significantly with tumor progression, especially with presence of metastasis. Patients with metastatic disease had statistically more tumorspheres as compared to patients without metastasis (30 vs 10/100µl blood, p<0.05). Patients with multiple metastasis had more tumorspheres compared to patients with single metastases (60 vs 30/100µl blood, p<0.05). The number of tumorspheres was positively correlated with proliferating index Ki-67 and grade score in primary breast tumor. Moreover, patients with HER2 positive tumors had more tumorspheres compared to patients with HER2 negative primary tumors (35 vs 10/100 µl blood, p<0.005). Conclusion:The number of tumorspheres cultured from peripheral blood directly reflects aggressiveness and proliferation capacity of primary tumor. The presence of tumorspheres with expression of PDL-1 might suggest their immunregulatory potential, but further studies are needed to validate the impact of PDL-1 expression on tumorspheres in patients with breast cancer. Citation Format: Monika Pizon, Dorothea Schott, Ulrich Pachmann, Katharina Pachmann. Determination of PD-L1 expression on tumorspheres cultured from the peripheral blood in patients with breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-04-08.

Programmed death-ligand 1 signaling and expression are reversible by lycopene via PI3K/AKT and Raf/MEK/ERK pathways in tongue squamous cell carcinoma

BackgroundCancer therapy targeting programmed death receptor-1 (PD-1 or CD279) or programmed death-ligand 1 (PD-L1 or CD274) gives hope to Tongue Squamous Cell Carcinoma (TSCC) treatment. However, the tumor-intrinsic mechanism of PD-L1 is not fully elucidated in TSCC. On the other hand, lycopene showed antitumor effects and chemotherapy/radiotherapy-enhancing effects by mechanisms closely correlated with PD-L1.PurposeWe aimed to explore whether the mechanisms of PD-L1 signaling and regulation are reversible by lycopene treatment in TSCC.MethodsWe collected TSCC tissues and normal tissues for assessment of PD-L1 expression by immunohistochemical technique and western blotting. We measured the expression of PD-L1 in three TSCC cell lines and constructed cell lines with knockdown and overexpression of PD-L1. Then, we measured the proliferation by CCK-8 assay, migration and invasion by Transwell assay, and apoptosis by TUNEL assay in five groups with treatment of blank control, negative control with vector transfection, PD-L1 knockdown/overexpression, 4 μM lycopene, and combined 4 μM lycopene and PD-L1 knockdown/overexpression. We also systematically analyzed the PD-L1 constitutive signaling pathways and their effect EMT pathways. In order to bring out the mechanism underlying PI3K/AKT depressing Raf/MEK/ERK, we used PI3K inhibitor LY294002.ResultsWe detected significant PD-L1 upregulation in biopsies by western blot and immunohistochemistry. Our study demonstrated that PD-L1 upregulation elevated IGF-1R to activate the PI3K/AKT pathway but inactivated the Raf/MEK/ERK pathway in TSCC cell line CAL27, while PD-L1 knockdown decreased IGF-1R to inactivate both PI3K/AKT and Raf/MEK/ERK pathways in cell line SCC9, to increase/decrease p-FOXOs and decrease/increase p-GSK-3β, producing further changes in EMT, proliferation, migration, invasion, and apoptosis. Lycopene reversed PD-L1 signaling and expression by mechanisms opposite to PD-L1 upregulation but similar to PD-L1 knockdown.ConclusionTaken together, this study firstly confirmed PD-L1 expression and signaling are reversible by lycopene via PI3K/AKT and Raf/MEK/ERK pathways in TSCC. Our study provides a sounder basis for comprehending PD-L1 signaling and expression and prevention and treatment of TSCC.

PD-L1 overexpression is Associated with Better Overall Survival in Triple-Negative Breast Cancer: A Meta-Analysis

PD-L1 overexpression is Associated with Better Overall Survival in Triple-Negative Breast Cancer: A Meta-Analysis

STAT1/IFIT2 signaling pathway is involved in PD-L1-mediated epithelial-to-mesenchymal transition in human esophageal cancer

BackgroundWe have previously reported significant change of epithelial to mesenchymal transition (EMT) phenotype of Eca-109 cells upon PD-L1 operation, and the cytoplasmic domain of PD-L1 played an essential role in promoting EMT of esophageal cancer cells. However, the underlying mechanism of how PD-L1 regulated EMT in esophageal cancer remained unclear.MethodsThe overexpression and knockdown expression models of PD-L1 and IFIT2 were established by using lenti-virus transfection and RNAi method. Western blotting, qRT-PCR, CCK8 assay, transwell assay and wound healing assay were chosen to investigate their impact on the cells. The expression levels of IFIT2 and EMT markers in esophageal cancer tissues were examined by immunohistochemical staining. The rescue experiments were further applied to investigate the role of STAT1/IFIT2 signal pathway in the PD-L1-mediated EMT. Luciferase reporter assays were performed to examine the IFIT2 promoter activities upon knockdown expression of PD-L1 to identify the putative targeted region of IFIT2 promoter.ResultsThe STAT1/IFIT2 signal pathway was activated when PD-L1 was knockdown in human esophageal cancer cells. Decreased IFIT2 expression significantly increased the cellular abilities of viability, invasion and migration by using RNAi method in human esophageal cancer cells. Decreased IFIT2 expression in esophageal cancer tissues significantly correlated with EMT status, and could be used as an independent prognostic predictor for the patients. Rescue experiments in PD-L1 knockdown cells further confirmed that STAT1/IFIT2 pathway was involved in the PD-L1 mediated EMT of esophageal cancer cells. Moreover, the luciferase reporter assay also confirmed that in esophageal cancer cells, the promoter region of IFIT2 (-3K~-1K) remains more active in PD-L1 knockdown expression cells compared with controls.ConclusionOur present work reveals a novel mechanism of how PD-L1 regulates EMT of cancer cells, namely STAT1/IFIT2 signal pathway is required in PD-L1 mediated EMT in human esophageal cancer.