PD-L1 and Emerging Biomarkers in Immune Checkpoint Blockade Therapy

Exploring immune checkpoint inhibitors: Focus on PD-1/PD-L1 axis and beyond

Immunotherapy emerges as a promising approach, marked by recent substantial progress in elucidating how the host immune response impacts tumor development and its sensitivity to various treatments. Immune checkpoint inhibitors have revolutionized cancer therapy by unleashing the power of the immune system to recognize and eradicate tumor cells. Among these, inhibitors targeting the programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have garnered significant attention due to their remarkable clinical efficacy across various malignancies. This review delves into the mechanisms of action, clinical applications, and emerging therapeutic strategies surrounding PD-1/PD-L1 blockade. We explore the intricate interactions between PD-1/PD-L1 and other immune checkpoints, shedding light on combinatorial approaches to enhance treatment outcomes and overcome resistance mechanisms. Furthermore, we discuss the expanding landscape of immune checkpoint inhibitors beyond PD-1/PD-L1, including novel targets such as CTLA-4, LAG-3, TIM-3, and TIGIT. Through a comprehensive analysis of preclinical and clinical studies, we highlight the promise and challenges of immune checkpoint blockade in cancer immunotherapy, paving the way for future advancements in the field.

The Immune Landscape and Its Potential for Immunotherapy in Advanced Biliary Tract Cancer

Biliary tract cancers (BTC) are a highly heterogeneous group of cancers at the genomic, epigenetic and molecular levels. The vast majority of patients initially present at an advanced (unresectable) disease stage due to a lack of symptoms and an aggressive tumour biology. Chemotherapy has been the mainstay of treatment in patients with advanced BTC but the survival outcomes and prognosis remain poor. The addition of immune checkpoint inhibitors (ICI) to chemotherapy have shown only a marginal benefit over chemotherapy alone due to the complex tumour immune microenvironment of these cancers. This review appraises our current understanding of the immune landscape of advanced BTC, including emerging transcriptome-based classifications, highlighting the mechanisms of immune evasion and resistance to ICI and their therapeutic implications. It describes the shifting treatment paradigm from traditional chemotherapy to immunotherapy combinations as well as the potential biomarkers for predicting response to ICI.

An Imaging-Based Assay to Measure the Location of PD-1 at the Immune Synapse for Testing the Binding Efficacy of Anti-PD-1 and Anti-PD-L1 Antibodies

PD-1 is an immune checkpoint on T cells. Antibodies to PD-1 or its ligand PD-L1 are gaining popularity as a leading immunotherapy approach. In the US, 40% of all cancer patients will be treated with anti-PD-1 or anti-PD-L1 antibodies but, unfortunately, only 30% will respond, and many will develop immune-related adverse events. There are nine FDA-approved anti-PD-1/PD-L1 antibodies, and approximately 100 are in different stages of clinical development. It is a clinical challenge to choose the correct antibody for a given patient, and this is critical in advanced malignancies, which often do not permit a second-line intervention. To resolve that, an in vitro assay to compare the performance of the different anti-PD-1/PD-L1 antibodies is not only a critical tool for research purposes but also a possible tool for personalized medicine. There are some assays describing the binding affinity and function of anti-PD-1/PD-L1 antibodies. However, a significant limitation of existing assays is that they need to consider the location of PD-1 in the immune synapse, the interface between the T cell and tumor cells, and, therefore, ignore a critical component in its biology. To address this, we developed and validated an imaging-based assay to quantify and compare the ability of different anti-PD-1/PD-L1 antibodies to remove PD-1 from the immune synapse. We correlated that with the same antibodies' ability to increase cytokine secretion from the targeted cells. The strong correlation between PD-1 location and its function in vitro and in vivo within the antibody treatment setting validates this assay's usability, which is easily recordable and straightforward. Key features • Live-cell imaging quantifies and compares how anti-PD-1 and anti-PD-L1 antibodies disrupt PD-1 localization, causing the removal of PD-1 during immune synapse formation. • Hao et al. [1] validated the protocol, and the findings were extended to a live confocal microscopy method. • It requires a Zeiss LSM 900 confocal microscope and appropriate imaging software and is optimized for the latest version of Zen Blue. • Anti-PD-1 antibodies are commonly used in cancer therapies, and this protocol optimizes the analysis of their effectiveness.

DAB2 + macrophages support FAP + fibroblasts in shaping tumor barrier and inducing poor clinical outcomes in liver cancer

Background: Cancer-associated fibroblasts (CAFs) are the key components of the immune barrier in liver cancer. Therefore, gaining a deeper understanding of the heterogeneity and intercellular communication of CAFs holds utmost importance in boosting immunotherapy effectiveness and improving clinical outcomes. Methods: A comprehensive analysis by combing single-cell, bulk, and spatial transcriptome profiling with multiplexed immunofluorescence was conducted to unravel the complexities of CAFs in liver cancer. Results: Through an integrated approach involving 235 liver cancer scRNA-seq samples encompassing over 1.2 million cells, we found that CAFs were particularly increased in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). FAP + fibroblasts were identified as the dominant subtype of CAFs, and which were mainly involved in extracellular matrix organization and angiogenesis. These CAFs were enriched in the tumor boundary of HCC, but diffusely scattered within ICC. The DAB2 + and SPP1 + tumor-associated macrophages (TAMs) reinforce the function of FAP + CAFs through signals such as TGF-β, PDGF, and ADM. Notably, the interaction between DAB2 + TAMs and FAP + CAFs promoted the formation of immune barrier and correlated with poorer patient survival, non-response to immunotherapy in HCC. High FAP and DAB2 immunohistochemical scores predicted shorter survival and higher serum AFP concentration in a local clinical cohort of 90 HCC patients. Furthermore, this communication pattern might be applicable to other solid malignancies as well. Conclusions: The interaction between DAB2 + TAMs and FAP + CAFs appears crucial in shaping the immune barrier. Strategies aimed at disrupting this communication or inhibiting the functions of FAP + CAFs could potentially enhance immunotherapy effectiveness and improve clinical outcomes.

PD-1/PD-L1 axis: implications in immune regulation, cancer progression, and translational applications

The PD-1/PD-L1 axis is a complex signaling pathway that has an important role in the immune system cells. Programmed cell death protein 1 (PD-1) acts as an immune checkpoint on the T lymphocytes, B lymphocytes, natural killer (NK), macrophages, dendritic cells (DCs), monocytes, and myeloid cells. Its ligand, the programmed cell death 1 ligand (PD-L1), is expressed in the surface of the antigen-presenting cells (APCs). The binding of both promotes the downregulation of the T cell response to ensure the activation to prevent the onset of chronic immune inflammation. This axis in the tumor microenvironment (TME) performs a crucial role in the tumor progression and the escape of the tumor by neutralizing the immune system, the engagement of PD-L1 with PD-1 in the T cell causes dysfunctions, neutralization, and exhaustion, providing the tumor mass production. This review will provide a comprehensive overview of the functions of the PD-1/PD-L1 system in immune function, cancer, and the potential therapeutic implications of the PD-1/PD-L1 pathway for cancer management.

Clinical, genomic and immune microenvironmental determinants of nivolumab response in head and neck squamous cell carcinoma

Background

In view of improving biomarkers predicting the efficacy of immunotherapy for head and neck squamous cell carcinoma (R/M HNSCC), this multicenter retrospective study aimed to identify clinical, tumor microenvironmental, and genomic factors that are related to therapeutic response to the anti- Programmed cell death protein 1 (PD-1) antibody, nivolumab, in patients with R/M HNSCC.

Methods

The study compared 53 responders and 47 non-responders, analyzing formalin-fixed paraffin-embedded samples using 14-marker multiplex immunohistochemistry and targeted gene sequencing.

Results

Of 100 patients included, responders had significantly lower smoking and alcohol index, higher incidence of immune related adverse events, and higher PD-1 ligand (PD-L1) expression in immune cells as well as PD-L1 combined positive score (CPS) than non-responders. The frequency of natural killer cells was associated with nivolumab response in patients with prior cetuximab use, but not in cetuximab-naïve status. Age-stratified analysis showed nivolumab response was linked to high CPS and lymphoid-inflamed profiles in patients aged ≥ 65. In contrast, lower NLR in peripheral blood counts was associated with response in patients aged < 65. Notably, TP53 mutation-positive group had lower CPS and T cell densities, suggesting an immune-excluded microenvironment. Patients with altered tumor suppressor gene pathways, including TP53, CDKN2A, and SMAD4 mutations, had lower CPS, higher smoking index, and were associated with poor responses.

Conclusion

Nivolumab treatment efficacy in HNSCC is influenced by a combination of clinical factors, age, prior treatment, immune environmental characteristics, and gene mutation profiles.

Identification and Application of Emerging Biomarkers in Treatment of Non-Small-Cell Lung Cancer: Systematic Review

Non-small-cell lung cancer (NSCLC) comprises approximately 85% of all lung cancer cases, often diagnosed at advanced stages, which diminishes the effective treatment options and survival rates. This systematic review assesses the utility of emerging biomarkers-circulating tumor DNA (ctDNA), microRNAs (miRNAs), and the blood tumor mutational burden (bTMB)-enhanced by next-generation sequencing (NGS) to improve the diagnostic accuracy, prognostic evaluation, and treatment strategies in NSCLC. Analyzing data from 37 studies involving 10,332 patients from 2020 to 2024, the review highlights how biomarkers like ctDNA and PD-L1 expression critically inform the selection of personalized therapies, particularly beneficial in the advanced stages of NSCLC. These biomarkers are critical for prognostic assessments and in dynamically adapting treatment plans, where high PD-L1 expression and specific genetic mutations (e.g., ALK fusions, EGFR mutations) significantly guide the use of targeted therapies and immunotherapies. The findings recommend integrating these biomarkers into standardized clinical pathways to maximize their potential in enhancing the treatment precision, ultimately fostering significant advancements in oncology and improving patient outcomes and quality of life. This review substantiates the prognostic and predictive value of these biomarkers and emphasizes the need for ongoing innovation in biomarker research.

Aberrant CD8+T cells drive reproductive dysfunction in female mice with elevated IFN-γ levels

Introduction

Interferon-gamma (IFN-γ) is pivotal in orchestrating immune responses during healthy pregnancy. However, its dysregulation, often due to autoimmunity, infections, or chronic inflammatory conditions, is implicated in adverse reproductive outcomes such as pregnancy failure or infertility. Additionally, the underlying immunological mechanisms remain elusive.

Methods

Here, we explore the impact of systemic IFN-γ elevation on cytotoxic T cell responses in female reproduction utilizing a systemic lupus-prone mouse model with impaired IFN-γ degradation.

Results

Our findings reveal that heightened IFN-γ levels triggered the infiltration of CD8+T cells in the pituitary gland and female reproductive tract (FRT), resulting in prolactin deficiency and subsequent infertility. Furthermore, we demonstrate that chronic IFN-γ elevation increases effector memory CD8+T cells in the murine ovary and uterus.

Discussion

These insights broaden our understanding of the role of elevated IFN-γ in female reproductive dysfunction and suggest CD8+T cells as potential immunotherapeutic targets in female reproductive disorders associated with chronic systemic IFN-γ elevation.

Tertiary lymphoid structural heterogeneity determines tumour immunity and prospects for clinical application

Tertiary lymphoid structures (TLS) are clusters of immune cells that resemble and function similarly to secondary lymphoid organs (SLOs). While TLS is generally associated with an anti-tumour immune response in most cancer types, it has also been observed to act as a pro-tumour immune response. The heterogeneity of TLS function is largely determined by the composition of tumour-infiltrating lymphocytes (TILs) and the balance of cell subsets within the tumour-associated TLS (TA-TLS). TA-TLS of varying maturity, density, and location may have opposing effects on tumour immunity. Higher maturity and/or higher density TLS are often associated with favorable clinical outcomes and immunotherapeutic response, mainly due to crosstalk between different proportions of immune cell subpopulations in TA-TLS. Therefore, TLS can be used as a marker to predict the efficacy of immunotherapy in immune checkpoint blockade (ICB). Developing efficient imaging and induction methods to study TA-TLS is crucial for enhancing anti-tumour immunity. The integration of imaging techniques with biological materials, including nanoprobes and hydrogels, alongside artificial intelligence (AI), enables non-invasive in vivo visualization of TLS. In this review, we explore the dynamic interactions among T and B cell subpopulations of varying phenotypes that contribute to the structural and functional diversity of TLS, examining both existing and emerging techniques for TLS imaging and induction, focusing on cancer immunotherapies and biomaterials. We also highlight novel therapeutic approaches of TLS that are being explored with the aim of increasing ICB treatment efficacy and predicting prognosis.

Adenosine increases PD-L1 expression in mesenchymal stromal cells derived from cervical cancer through its interaction with A2AR/A2BR and the production of TGF-β1

Mesenchymal stromal cells (MSCs) together with malignant cells present in the tumor microenvironment (TME), participate in the suppression of the antitumor immune response through the production of immunosuppressive factors, such as transforming growth factor beta 1 (TGF-β1). In previous studies, we reported that adenosine (Ado), generated by the adenosinergic activity of cervical cancer (CeCa) cells, induces the production of TGF-β1 by interacting with A2AR/A2BR. In the present study, we provide evidence that Ado induces the production of TGF-β1 in MSCs derived from CeCa tumors (CeCa-MSCs) by interacting with both receptors and that TGF-β1 acts in an autocrine manner to induce the expression of programmed death ligand 1 (PD-L1) in CeCa-MSCs, resulting in an increase in their immunosuppressive capacity on activated CD8+ T lymphocytes. The addition of the antagonists ZM241385 and MRS1754, specific for A2AR and A2BR, respectively, or SB-505124, a selective TGF-β1 receptor inhibitor, in CeCa-MSC cultures significantly inhibited the expression of PD-L1. Compared with CeCa-MSCs, MSCs derived from normal cervical tissue (NCx-MSCs), used as a control and induced with Ado to express PD-L1, showed a lower response to TGF-β1 to increase PD-L1 expression. Those results strongly suggest the presence of a feedback mechanism among the adenosinergic pathway, the production of TGF-β1, and the induction of PD-L1 in CeCa-MSCs to suppress the antitumor response of CD8+ T lymphocytes. The findings of this study suggest that this pathway may have clinical importance as a therapeutic target.

SAFFRON-103: a phase Ib study of sitravatinib plus tislelizumab in anti-PD-(L)1 refractory/resistant advanced melanoma

Aim: Investigate TKI sitravatinib plus anti-PD-1 antibody tislelizumab in patients with unresectable/advanced/metastatic melanoma with disease progression on/after prior first-line anti-PD-(L)1 monotherapy. Methods: Open-label, multicenter, multicohort study (NCT03666143). Patients in the melanoma cohort (N = 25) received sitravatinib once daily plus tislelizumab every 3 weeks. The primary end point was safety and tolerability. Results: Treatment-emergent adverse events (TEAEs) occurred in all patients, with ≥grade 3 TEAEs in 52.0%. Most TEAEs were mild-or-moderate in severity, none were fatal, and few patients discontinued treatment owing to TEAEs (12.0%). Objective response rate was 36.0% (95% CI: 18.0-57.5). Median progression-free survival was 6.7 months (95% CI: 4.1-not estimable). Conclusion: Sitravatinib plus tislelizumab had manageable safety/tolerability in patients with anti-PD-(L)1 refractory/resistant unresectable/advanced/metastatic melanoma, with promising antitumor activity. Clinical Trial Registration: NCT03666143 (ClinicalTrials.gov).

TRIM29 promotes antitumor immunity through enhancing IGF2BP1 ubiquitination and subsequent PD-L1 downregulation in gastric cancer

Tripartite motif-containing protein 29 (TRIM29) is a member of TRIM family protein which has been reported to play a role in the progress of inflammatory and cancer diseases. However, its specific role in gastric cancer (GC) has yet to be fully understood. Here, we investigated the expression of TRIM29 in gastric cancer and its functions in the antitumor immunity. TRIM29 expression was lower in tumor tissues than that in paired normal tissues. Lower expression of TRIM29 was related to aberrant hypermethylation of CpG islands in TRIM29 gene. Comprehensive proteomics and immunoprecipitation analyses identified IGF2BP1 as TRIM29 interactors. TRIM29 interacted with IGF2BP1 and induced its ubiquitination at Lys440 and Lys450 site by K48-mediated linkage for protein degradation. IGF2BP1 promoted PD-L1 mRNA stability and expression in a 3'UTR and m6A-dependent manner. Functionally, TRIM29 enhanced antitumor T-cell immunity in gastric cancer dependent on the IGF2BP1/PD-L1 axis in vivo and in vitro. Clinical correlation analysis revealed that TRIM29 expression in patient samples was associated with CD8+ immune cell infiltration in the GC microenvironment and the overall survival rates of GC patients. Our findings revealed a crucial role of TRIM29 in regulating the antitumor T-cell immunity in GC. We also suggested that the TRIM29/IGF2BP1/PD-L1 axis could be used as a diagnostic and prognostic marker of gastric cancer and a promising target for GC immunotherapy.

Enhancing immunogenic responses through CDK4/6 and HIF2α inhibition in Merkel cell carcinoma

Approximately 50% of Merkel cell carcinoma (MCC) patients facing this highly aggressive skin cancer initially respond positively to PD-1-based immunotherapy. Nevertheless, the recurrence of MCC post-immunotherapy emphasizes the pressing need for more effective treatments. Recent research has highlighted Cyclin-dependent kinases 4 and 6 (CDK4/6) as pivotal cell cycle regulators gaining prominence in cancer studies. This study reveals that the CDK4/6 inhibitor, palbociclib can enhance PD-L1 gene transcription and surface expression in MCC cells by activating HIF2α. Inhibiting HIF2α with TC-S7009 effectively counteracts palbociclib-induced PD-L1 transcription and significantly intensifies cell death in MCC. Simultaneously, co-targeting CDK4/6 and HIF2α boosts ROS levels while suppressing SLC7A11, a key regulator of cellular redox balance, promoting ferroptosis- a form of immunogenic cell death linked to iron. Considering the rising importance of immunogenic cell death in immunotherapy, this strategy holds promise for improving future MCC treatments, markedly increasing immunogenic cell death various across various MCC cell lines, thus advancing cancer immunotherapy.

A near-infrared fluorescence-enhancing plasmonic biosensing microarray identifies soluble PD-L1 and ICAM-1 as predictive checkpoint biomarkers for cancer immunotherapy

Sensitive and accurate biomarker-driven assay guidance has been widely adopted to identify responsive patients for immune checkpoint blockade (ICB) therapy to impede disease progression and extend survival. However, most current assays are invasive, requiring surgical pathology specimens and only informing monochronic information. Here, we report a multiplexed enhanced fluorescence microarray immunoassay (eFMIA) based on a nanostructured gold nanoisland substrate (AuNIS), which macroscopically amplifies near-infrared fluorescence (NIRF) of a structurally symmetric IRDye78 fluorophore by over two orders of magnitude of 202.6-fold. Aided by non-contact piezo-driven micro-dispensing (PDMD), eFMIA simultaneously and semi-quantitatively detected intracellular and secreted programmed death-ligand 1 (PD-L1) and intercellular adhesion molecule-1 (ICAM-1) in human nasopharyngeal carcinoma (NPC) cells. The assay performance was superior to fluorescence immunoassays (FIA) and enzyme-linked immunosorbent assays (ELISA), with lower detection limits. Using eFMIA, we found significantly differential levels of soluble PD-L1 (sPD-L1) and sICAM-1 in the sera of 28 cancer patients, with different clinical outcomes following anti-PD-1 ICB therapy. With a well-characterized mechanism, the high-performance plasmonic multiplexed assay with the composite biomarkers may be a valuable tool to assist clinicians with decision-making and patient stratification to afford predictive ICB therapy responses.

Full eradication of pre-clinical human papilloma virus-induced tumors by a lentiviral vaccine

Human papillomavirus (HPV) infections are the cause of all cervical and numerous oropharyngeal and anogenital cancers. The currently available HPV vaccines, which induce neutralizing antibodies, have no therapeutic effect on established tumors. Here, we developed an immuno-oncotherapy against HPV-induced tumors based on a non-integrative lentiviral vector encoding detoxified forms of the Early E6 and E7 oncoproteins of HPV16 and 18 genotypes, namely, "Lenti-HPV-07". A single intramuscular injection of Lenti-HPV-07 into mice bearing established HPV-induced tumors resulted in complete tumor eradication in 100% of the animals and was also effective against lung metastases. This effect correlated with CD8+ T-cell induction and profound remodeling of the tumor microenvironment. In the intra-tumoral infiltrates of vaccinated mice, the presence of large amounts of activated effector, resident memory, and transcription factor T cell factor-1 (TCF-1)+ "stem-like" CD8+ T cells was associated with full tumor eradication. The Lenti-HPV-07-induced immunity was long-lasting and prevented tumor growth after a late re-challenge, mimicking tumor relapse. Lenti-HPV-07 therapy synergizes with an anti-checkpoint inhibitory treatment and therefore shows promise as an immuno-oncotherapy against established HPV-mediated malignancies.

Immune checkpoint inhibitors: maximizing benefit whilst minimizing toxicity

INTRODUCTION

The advent of immunotherapy has revolutionized the treatment of cancer; anti-tumor efficacy has been observed with immune checkpoint inhibitors (ICI) in ~20 different cancer types with durable responses in some cases. However, the risk of toxicity in the form of immune-related adverse events (irAE) partially counterbalances these benefits, and there are no FDA-approved biomarkers to categorize patients by likelihood of response or risk of irAEs.

AREAS COVERED

We conducted a thorough review of the literature of clinical studies regarding ICI and their toxicities. In this review, we synthesize the current body of literature about ICI treatment and irAE by summarizing the classes and uses of ICI, how to identify patients at risk for irAE, present the current understanding of irAE development, describe ongoing research into biomarkers of irAE, examine opportunities for irAE prevention, described management of steroid refractory irAE, and highlight future directions for development of prevention and management strategies.

EXPERT OPINION

While ongoing biomarker studies are promising, it is unlikely that there will be a 'one-size-fits-all' approach to categorizing irAE risk. In contrast, improved management and irAE prophylaxis are potentially in reach, and ongoing trials will help elucidate best practices.

Unsupervised Hierarchical Clustering of Head and Neck Cancer Patients by Pre-Treatment Plasma Metabolomics Creates Prognostic Metabolic Subtypes

There is growing evidence that the metabolism is deeply intertwined with head and neck squamous cell carcinoma (HNSCC) progression and survival but little is known about circulating metabolite patterns and their clinical potential. We performed unsupervised hierarchical clustering of 209 HNSCC patients via pre-treatment plasma metabolomics to identify metabolic subtypes. We annotated the subtypes via pathway enrichment analysis and investigated their association with overall and progression-free survival. We stratified the survival analyses by smoking history. High-resolution metabolomics extracted 186 laboratory-confirmed metabolites. The optimal model created two patient clusters, of subtypes A and B, corresponding to 41% and 59% of the study population, respectively. Fatty acid biosynthesis, acetyl-CoA transport, arginine and proline, as well as the galactose metabolism pathways differentiated the subtypes. Relative to subtype B, subtype A patients experienced significantly worse overall and progression-free survival but only among ever-smokers. The estimated three-year overall survival was 61% for subtype A and 86% for subtype B; log-rank p = 0.001. The association with survival was independent of HPV status and other HNSCC risk factors (adjusted hazard ratio = 3.58, 95% CI: 1.46, 8.78). Our findings suggest that a non-invasive metabolomic biomarker would add crucial information to clinical risk stratification and raise translational research questions about testing such a biomarker in clinical trials.

Carbonic Anhydrase IX Suppression Shifts Partial Response to Checkpoint Inhibitors into Complete Tumor Eradication: Model-Based Investigation

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of solid malignancies, including non-small-cell lung cancer. However, immunotherapy resistance constitutes a significant challenge. To investigate carbonic anhydrase IX (CAIX) as a driver of resistance, we built a differential equation model of tumor-immune interactions. The model considers treatment with the small molecule CAIX inhibitor SLC-0111 in combination with ICIs. Numerical simulations showed that, given an efficient immune response, CAIX KO tumors tended toward tumor elimination in contrast to their CAIX-expressing counterparts, which stabilized close to the positive equilibrium. Importantly, we demonstrated that short-term combination therapy with a CAIX inhibitor and immunotherapy could shift the asymptotic behavior of the original model from stable disease to tumor eradication. Finally, we calibrated the model with data from murine experiments on CAIX suppression and combination therapy with anti-PD-1 and anti-CTLA-4. Concluding, we have developed a model that reproduces experimental findings and enables the investigation of combination therapies. Our model suggests that transient CAIX inhibition may induce tumor regression, given a sufficient immune infiltrate in the tumor, which can be boosted with ICIs.

PD-L1 expression downregulation by RNF43 in gastric carcinoma enhances antitumour activity of T cells

Ring finger protein 43 (RNF43), a transmembrane E3 ubiquitin ligase, has been indicated to be a potential biomarker for gastric cancer treatment, as this protein increases tumour cell apoptosis and suppresses cellular proliferation. The role of RNF43 in cellular immunotherapy remains unclear. Herein, we aimed to explore the expression level of RNF43 in gastric cancer cell lines and its role in cellular immunotherapy. The expression level of RNF43 and PD-L1 and their correlation in gastric cancer cell lines were analysed. The expression of PD-L1 was negatively correlated with that of RNF43 in gastric cancer cell lines. RNF43 interacted with PD-L1 to augment both K48- and K63-linked ubiquitination of PD-L1 in gastric cancer cell lines. In addition, RNF43 expression in gastric cancer cell lines could enhance the antitumour activity of T cells. In conclusion, this study reveals that RNF43 can inhibit PD-L1 expression to enhance the antitumour activity of cellular immunotherapy.

Spatial PD-L1, immune-cell microenvironment, and genomic copy-number alteration patterns and drivers of invasive-disease transition in prospective oral precancer cohort

BACKGROUND

Studies of the immune landscape led to breakthrough trials of programmed death-1 (PD-1) inhibitors for recurrent/metastatic head and neck squamous cell carcinoma therapy. This study investigated the timing, influence of somatic copy-number alterations (SCNAs), and clinical implications of PD-L1 and immune-cell patterns in oral precancer (OPC).

METHODS

The authors evaluated spatial CD3, CD3/8, and CD68 density (cells/mm2 ) and PD-L1 (membranous expression in cytokeratin-positive intraepithelial neoplastic cells and CD68) patterns by multiplex immunofluorescence in a 188-patient prospective OPC cohort, characterized by clinical, histologic, and SCNA risk factors and protocol-specified primary end point of invasive cancer. The authors used Wilcoxon rank-sum and Fisher exact tests, linear mixed effect models, mediation, and Cox regression and recursive-partitioning analyses.

RESULTS

Epithelial, but not CD68 immune-cell, PD-L1 expression was detected in 28% of OPCs, correlated with immune-cell infiltration, 9p21.3 loss of heterozygosity (LOH), and inferior oral cancer-free survival (OCFS), notably in OPCs with low CD3/8 cell density, dysplasia, and/or 9p21.3 LOH. High CD3/8 cell density in dysplastic lesions predicted better OCFS and eliminated the excess risk associated with prior oral cancer and dysplasia. PD-L1 and CD3/8 patterns revealed inferior OCFS in PD-L1 high intrinsic induction and dysplastic immune-cold subgroups.

CONCLUSION

This report provides spatial insight into the immune landscape and drivers of OPCs, and a publicly available immunogenomic data set for future precancer interrogation. The data suggest that 9p21.3 LOH triggers an immune-hot inflammatory phenotype; whereas increased 9p deletion size encompassing CD274 at 9p24.1 may contribute to CD3/8 and PD-L1 depletion during invasive transition. The inferior OCFS in PD-L1-high, immune-cold OPCs support the development of T-cell recruitment strategies.

Development and validation of an integrative pan-solid tumor predictor of PD-1/PD-L1 blockade benefit

BACKGROUND

Anti-PD-1 and PD-L1 (collectively PD-[L]1) therapies are approved for many advanced solid tumors. Biomarkers beyond PD-L1 immunohistochemistry, microsatellite instability, and tumor mutation burden (TMB) may improve benefit prediction.

METHODS

Using treatment data and genomic and transcriptomic tumor tissue profiling from an observational trial (NCT03061305), we developed Immunotherapy Response Score (IRS), a pan-tumor predictive model of PD-(L)1 benefit. IRS real-world progression free survival (rwPFS) and overall survival (OS) prediction was validated in an independent cohort of trial patients.

RESULTS

Here, by Cox modeling, we develop IRS-which combines TMB with CD274, PDCD1, ADAM12 and TOP2A quantitative expression-to predict pembrolizumab rwPFS (648 patients; 26 tumor types; IRS-High or -Low groups). In the 248 patient validation cohort (248 patients; 24 tumor types; non-pembrolizumab PD-[L]1 monotherapy treatment), median rwPFS and OS are significantly longer in IRS-High vs. IRS-Low patients (rwPFS adjusted hazard ratio [aHR] 0.52, p = 0.003; OS aHR 0.49, p = 0.005); TMB alone does not significantly predict PD-(L)1 rwPFS nor OS. In 146 patients treated with systemic therapy prior to pembrolizumab monotherapy, pembrolizumab rwPFS is only significantly longer than immediately preceding therapy rwPFS in IRS-High patients (interaction test p = 0.001). In propensity matched lung cancer patients treated with first-line pembrolizumab monotherapy or pembrolizumab+chemotherapy, monotherapy rwPFS is significantly shorter in IRS-Low patients, but is not significantly different in IRS-High patients. Across 24,463 molecularly-evaluable trial patients, 7.6% of patients outside of monotherapy PD-(L)1 approved tumor types are IRS-High/TMB-Low.

CONCLUSIONS

The validated, predictive, pan-tumor IRS model can expand PD-(L)1 monotherapy benefit outside currently approved indications.

NEPTUNE China cohort: First-line durvalumab plus tremelimumab in Chinese patients with metastatic non-small-cell lung cancer

OBJECTIVES

The phase 3 NEPTUNE study (NCT02542293) evaluated first-line durvalumab plus tremelimumab (DT) versus chemotherapy for metastatic NSCLC. Prespecified exploratory analyses were conducted in an extended cohort enrolled in China.

MATERIALS AND METHODS

Patients were randomized (1:1) to DT or standard chemotherapy, stratified by PD-L1 tumor cell (TC) expression (≥25 % vs < 25 %), histology, and smoking history. The primary analysis for this cohort was overall survival (OS) in patients with PD-L1 TC < 1 %. Secondary analyses included OS and progression-free survival (PFS) in the ITT population and PD-L1 subgroups, and safety. No alpha was allocated to these cohort analyses (data cut-off, 21-September-2020).

RESULTS

78 and 82 patients were randomized to DT and chemotherapy, respectively; 26 and 29 had PD-L1 TC < 1 % (median follow-up, 31.2 and 29.7 months [censored patients]). Among patients with PD-L1 TC < 1 %, OS favored DT versus chemotherapy (HR 0.60; 95 % CI, 0.32-1.11), with medians of 15.0 months (95 % CI, 10.5-27.4) and 11.7 months (95 % CI, 8.6-20.5), respectively; 24-month rates were 36.0 % (95 % CI, 18.2-54.2) and 17.9 % (95 % CI, 6.5-33.7). In the ITT population, OS was prolonged with DT versus chemotherapy (HR 0.70; 95 % CI, 0.48-1.02); medians were 20.0 and 14.1 months and 24-month rates were 44.2 % and 30.4 %. PFS was similar in the PD-L1 TC < 1 % (HR 1.13; 95 % CI, 0.59-2.14) and ITT (HR 0.95; 95 % CI, 0.66-1.36) populations; 12-month rates were 15.6 % versus 11.3 % and 23.9 % versus 16.6 %. Grade 3/4 treatment-related adverse events (TRAEs) occurred in 31.2 % with DT and 52.6 % with chemotherapy; 3.9 % versus 10.3 % discontinued due to TRAEs.

CONCLUSIONS

In exploratory analyses, first-line DT showed a trend towards improved OS versus chemotherapy among Chinese patients in the PD-L1 TC < 1 % population and ITT population, with 24-month OS and 12-month PFS rates indicating benefit in survival curve tails. DT was well tolerated with no new safety signals.

PD-L1 testing by immunohistochemistry in immuno-oncology

Immunotherapy, based on immune checkpoint inhibitors targeting the Programmed cell death ligand 1 (PD-L1) and/or Programmed Death Receptor 1 (PD-1), has substantially improved the outcomes of patients with various cancers. However, only ~30% of patients benefit from immune checkpoint inhibitors. Tumor PD-L1 expression, assessed by immunohistochemistry, is the most widely validated and used predictive biomarker to guide the selection of patients for immune checkpoint inhibitors. PD-L1 assessment may be challenging due to the necessity for different companion diagnostic assays for required specific immune checkpoint inhibitors and a relatively high level of inter-assay variability in terms of performance and cutoff levels. In this review, we discuss the role of PD-L1 immunohistochemistry as a predictive test in immunotherapy (immuno-oncology), highlight the complexity of the PD-L1 testing landscape, discuss various preanalytical, analytical and clinical issues that are associated with PD-L1 assays, and provide some insights into optimization of PD-L1 as a predictive biomarker in immuno-oncology.

NEPTUNE: Phase 3 Study of First-Line Durvalumab Plus Tremelimumab in Patients With Metastatic NSCLC

INTRODUCTION

NEPTUNE, a phase 3, open-label study, evaluated first-line durvalumab plus tremelimumab versus chemotherapy in metastatic NSCLC (mNSCLC).

METHODS

Eligible patients with EGFR and ALK wild-type mNSCLC were randomized (1:1) to first-line durvalumab (20 mg/kg every 4 weeks until progression) plus tremelimumab (1 mg/kg every 4 weeks for up to four doses) or standard chemotherapy. Randomization was stratified by tumor programmed death-ligand 1 expression (≥25% versus <25%), tumor histologic type, and smoking history. The amended primary end point was overall survival (OS) in patients with blood tumor mutational burden (bTMB) greater than or equal to 20 mutations per megabase (mut/Mb). Secondary end points included progression-free survival (PFS) in patients with bTMB greater than or equal to 20 mut/Mb and safety and tolerability in all treated patients.

RESULTS

As of June 24, 2019, 823 patients were randomized (intention-to-treat [ITT]); 512 (62%) were bTMB-evaluable, with 129 of 512 (25%) having bTMB greater than or equal to 20 mut/Mb (durvalumab plus tremelimumab [n = 69]; chemotherapy [n = 60]). Baseline characteristics were balanced in the intention-to-treat. Among patients with bTMB greater than or equal to 20 mut/Mb, OS improvement with durvalumab plus tremelimumab versus chemotherapy did not reach statistical significance (hazard ratio 0.71 [95% confidence interval: 0.49-1.05; p = 0.081]; median OS, 11.7 versus 9.1 months); the hazard ratio for PFS was 0.77 (95% confidence interval, 0.51-1.15; median PFS, 4.2 versus 5.1 months). In the overall safety population, incidence of grade 3 or 4 treatment-related adverse events was 20.7% (durvalumab plus tremelimumab) and 33.6% (chemotherapy).

CONCLUSIONS

NEPTUNE did not meet its primary end point of improved OS with durvalumab plus tremelimumab versus chemotherapy in patients with mNSCLC and bTMB greater than or equal to 20 mut/Mb. Despite the amended study design, with a resultant small primary analysis population, therapeutic activity was aligned with expectations based on mechanistic biology and previous studies.

An in silico model to study the impact of carbonic anhydrase IX expression on tumour growth and anti-PD-1 therapy

Immune checkpoint inhibitors (ICIs) are revolutionary cancer treatments. However, the mechanisms behind their effectiveness are not yet fully understood. Here, we aimed to investigate the role of the pH-regulatory enzyme carbonic anhydrase IX (CAIX) in ICI success. Consequently, we developed an in silico model of the tumour microenvironment. The hybrid model consists of an agent-based model of tumour-immune cell interactions, coupled with a set of diffusion-reaction equations describing substances in the environment. It is calibrated with data from the literature, enabling the study of its qualitative behaviour. In our model, CAIX-expressing tumours acidified their neighbourhood, thereby reducing immune infiltration by 90% (p < 0.001) and resulting in a 25% increase in tumour burden (p < 0.001). Moreover, suppression of CAIX improved the response to anti-PD-1 (23% tumour reduction in CAIX knockouts and 6% in CAIX-expressing tumours, p < 0.001), independently of initial PD-L1 expression. Our simulations suggest that patients with CAIX-expressing tumours could respond favourably to combining ICIs with CAIX suppression, even in the absence of pre-treatment PD-L1 expression. Furthermore, when calibrated with tumour-type-specific data, our model could serve as a high-throughput tool for testing the effectiveness of such a combinatorial approach.

New Biomarkers and Immunotherapy Decision

As immune checkpoint blockade and other immune-based therapy approaches lead to broad treatment advances among patients with advanced cancer, an important consideration is how to best select patients whose tumors will respond to these therapies. As a consequence predictive and prognostic markers are needed. There are genomic features, such as tumour mutation burden (TMB), microsatellite instability (MSI), and immune phenotype features, such as programmed death-ligand 1 (PD-L1), CTLA-4 and tumour infiltrating lymphocytes (TILs), to predict response to immunotherapies (ITs). Several studies show the correlation between TMB and predicted neoantigen load across multiple cancer types. Response to immune checkpoint inhibitors is higher in tumours with high TMB. The candidate biomarker that has been studied mostly other than TMB is PD-L1 expression in trials utilizing programmed cell death-1 (PD-1) blockade. PD-L1 and PD-1 expression are dynamic markers that change in relation to local cytokines and other factors, and the thresholds that separate “positive” and “negative” PD-L1 expressions remain under debate. PD-L1 expression is now a routine diagnostic marker for patients with newly diagnosed NSCLC. The potential applicability of PD-L1 in other disease settings is still uncertain. Microsatellite instability is characterised by high rates of alterations to repetitive DNA sequences caused by impaired mismatch repair (MMR); MSI was the biomarker was approved according to tumor's initial location. Combining TMB with specific genomic alterations is crucial. Moreover, new biomarkers are being investigated.

A multi-omic single cell sequencing approach to develop a CD8 T cell specific gene signature for anti-PD1 response in solid tumors

Immune checkpoint blockade (ICB) has led to durable clinical responses in multiple cancer types. However, biomarkers that identify which patients are most likely to respond to ICB are not well defined. Many putative biomarkers developed from a small number of samples often fail to maintain their predictive status in larger validation cohorts. We show across multiple human malignancies and syngeneic murine tumor models that neither pretreatment T cell receptor (TCR) clonality nor changes in clonality after ICB correlate with response. Dissection of tumor infiltrating lymphocytes pre- and post-ICB by paired single-cell RNA sequencing and single-cell TCR sequencing reveals conserved and distinct transcriptomic features in expanded TCR clonotypes between anti-PD1 responder and nonresponder murine tumor models. Overall, our results indicate a productive anti-tumor response is agnostic of TCR clonal expansion. Further, we used single-cell transcriptomics to develop a CD8⁺ T cell specific gene signature for a productive anti-tumor response and show the response signature to be associated with overall survival (OS) on nivolumab monotherapy in CheckMate-067, a phase 3 clinical trial in metastatic melanoma. These results highlight the value of leveraging single-cell assays to dissect heterogeneous tumor and immune subsets and define cell-type specific transcriptomic biomarkers of ICB response.

Noninvasive interrogation of CD8+ T cell effector function for monitoring tumor early responses to immunotherapy

Accurately identifying patients who respond to immunotherapy remains clinically challenging. A noninvasive method that can longitudinally capture information about immune cell function and assist in the early assessment of tumor responses is highly desirable for precision immunotherapy. Here, we show that PET imaging using a granzyme B–targeted radiotracer named ⁶⁸Ga-grazytracer, could noninvasively and effectively predict tumor responses to immune checkpoint inhibitors and adoptive T cell transfer therapy in multiple tumor models. ⁶⁸Ga-grazytracer was designed and selected from several radiotracers based on non-aldehyde peptidomimetics, and exhibited excellent in vivo metabolic stability and favorable targeting efficiency to granzyme B secreted by effector CD8⁺ T cells during immune responses. ⁶⁸Ga-grazytracer permitted more sensitive discrimination of responders and nonresponders than did ¹⁸F-fluorodeoxyglucose, distinguishing between tumor pseudoprogression and true progression upon immune checkpoint blockade therapy in mouse models with varying immunogenicity. In a preliminary clinical trial with 5 patients, no adverse events were observed after ⁶⁸Ga-grazytracer injection, and clinical responses in cancer patients undergoing immunotherapy were favorably correlated with ⁶⁸Ga-grazytracer PET results. These results highlight the potential of ⁶⁸Ga-grazytracer PET to enhance the clinical effectiveness of granzyme B secretion–related immunotherapies by supporting early response assessment and precise patient stratification in a noninvasive and longitudinal manner.

Evaluation PD-L1, CD8 and CD20 as early predictor and tracking markers for breast cancer (BC) in Egypt

Background

Breast cancer (BC) is considered as a common type of cancer threatening women throughout the world. Therefore, development of early predication biomarkers for BC got more concern especially for Egyptian females. This study was aimed to evaluate PD-L1, CD8, and CD20 as early prediction breast cancer biomarkers.

Methods

Flow cytometry (FC), immunohistochemistry (IHC), Western Blot, and q-PCR were used to compare PD-L1, CD20, and CD8 levels in tissues and blood samples of Breast Cancer and controls.

Results

Blood samples showed a significant increase in PD-L1, CD20, and CD8 compared to controls (p˂0.005). A Significant correlation was shown between PD-L1, CD8, and CD20 in tissue and breast cancer subtypes. Whereas, invasive lobular carcinoma (ILC) was characterized by superior PD-L1 and CD20 levels compared to invasive ductal carcinoma (IDC). FC studies on Blood showed 83% and 45.7% PD-L1 expressions for IDC and ILC, respectively. CD20 in ILC and IDC were 78.2% and 62.5%, respectively. Nevertheless, CD8 was 74.2% for IDC and 67.7% for ILC. Whereas, FC studies for PD-L1, CD20, and CD8 in ILC in tissues gave 34.4%, 30.2% and 35.1%, respectively. In addition, IDC tissue samples showed 16%, 12.5, and 13.5% for PD-L1, CD20, and CD8. The moderate stage of adenocarcinoma caused expression of PD-L1 within inflammatory cells, while expression was within neoplastic glandular cells in late stage.

Conclusion

PD-L1, CD8, and CD20 are considered as early predictor and tracking markers for breast cancer.

Immunohistochemical assessment of PD-L1 expression using three different monoclonal antibodies in triple negative breast cancer patients

Background

PD-L1 receptor expression in breast cancer tissue can be assessed with different anti-human PD-L1 monoclonal antibodies. The performance of three specific monoclonal antibodies in a head-to-head comparison is unknown. In addition, a potential correlation of PD-L1 expression and clinico-pathological parameters has not been investigated.

Methods

This was a retrospective study on tissue samples of patients with histologically confirmed triple negative breast cancer (TNBC). PD-L1 receptors were immune histochemically stained with three anti-human PD-L1 monoclonal antibodies: 22C3 and 28-8 for staining of tumor cell membranes (TC) and cytoplasm (Cyt), SP142 for immune cell staining (IC). Three different tissue samples of each patient were evaluated separately by two observers in a blinded fashion. The percentage of PD-L1 positive tumor cells in relation to the total number of tumor cells was determined. For antibodies 22C3 and 28-8 PD-L1 staining of 0 to < 1% of tumor cells was rated "negative", 1–50% was rated "positive" and > 50% was rated "strong positive". Cyt staining was defined as “negative” when no signal was observed and as “positive”, when any positive signal was observed. For IC staining with SP142 all samples with PD-L1 expression ≥ 1% were rated as “positive”. Finally, the relationship between PD-L1 expression and clinico-pathological parameters was analyzed.

Results

Tissue samples from 59 of 60 enrolled patients could be analyzed. Mean age was 55 years. Both the monoclonal antibodies 22C3 and 28-8 had similar properties, and were positive for both TC in 13 patients (22%) and for Cyt staining in 24 patients (40.7%). IC staining with antibody SP142 was positive in 24 patients (40.7%), who were also positive for Cyt staining. The differences between TC and Cyt staining and TC and IC staining were significant (p = 0.001). Cases with positive TC staining showed higher Ki67 expression compared to those with negative staining, 40 vs 30%, respectively (p = 0.05). None of the other clinico-pathological parameters showed any correlation with PDL1 expression.

Conclusions

Antibodies 22C3 and 28-8 can be used interchangeably for PD-L1 determination in tumor cells of TNBC patients. Results for Cyt staining with 22C3 or 28-8 and IC staining with SP142 were identical. In our study PD-L1 expression correlates with Ki67 expression but not with OS or DFS.

The clinical utility and safety of short-course immune checkpoint inhibitors in multiple tumours-A real-world multicentric study from India

The real-world data on short course of immune checkpoint inhibitor (ICI) use are sparse and merit exploration. A multicentric observational study on the safety and efficacy of ICI in oncology patients between August 2014 and October 2020 involves 1011 patients across 13 centers in India. The median age was 59 (min 16-max 98) years with male preponderance (77.9%). The predominant cohort received short-course ICI therapy; the median number of cycles was 5 (95% confidence interval [CI] 1-27), and the median duration of therapy was 3 (95% CI 0.5-13) months. ICIs were used commonly in the second and third line setting in our study (66.4%, n = 671). Objective response rate (complete or partial response) was documented in 254 (25.1%) of the patients, 202 (20.0%) had stable disease, and 374 (37.0%) had progressive disease. The clinical benefit rate was present in 456 (45.1%). Among the patients whom ICI was stopped (n = 906), the most common reason for cessation of ICI was disease progression (616, 68.0%) followed by logistic reasons like financial constraints (234, 25.82%). With a median follow-up of 14.1 (95% CI 12.9-15.3) months, there were 616 events of progression and 443 events of death, and the median progression free survival and overall survival were 6.4 (95% CI 5.5-7.3) and 13.6 (95% CI 11.6-15.7) months, respectively, in the overall cohort. Among the immune-related adverse events, autoimmune pneumonitis (29, 3.8%) and thyroiditis (24, 2.4%) were common. Real-world multicentric Indian data predominantly with short-course ICI therapy have comparable efficacy/safety to international literature with standard ICI therapy.

Quantifying the contribution of transcription factor activity, mutations and microRNAs to CD274 expression in cancer patients

Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed cell death protein ligand 1 (PD-L1) axis have been remarkably successful in inducing tumor remissions in several human cancers, yet a substantial number of patients do not respond to treatment. Because this may be partially due to the mechanisms giving rise to high PD-L1 expression within a patient, it is highly relevant to fully understand these mechanisms. In this study, we conduct a bioinformatic analysis to quantify the relative importance of transcription factor (TF) activity, microRNAs (miRNAs) and mutations in determining PD-L1 (CD274) expression at mRNA level based on data from the Cancer Genome Atlas. To predict individual CD274 levels based on TF activity, we developed multiple linear regression models by taking the expression of target genes of the TFs known to directly target PD-L1 as independent variables. This analysis showed that IRF1, STAT1, NFKB and BRD4 are the most important regulators of CD274 expression, explaining its mRNA levels in 90–98% of the patients. Because the remaining patients had high CD274 levels independent of these TFs, we next investigated whether mutations associated with increased CD274 mRNA levels, and low levels of miRNAs associated with negative regulation of CD274 expression could cause high CD274 levels in these patients. We found that mutations or miRNAs offered an explanation for high CD274 levels in 81–100% of the underpredicted patients. Thus, CD274 expression is largely explained by TF activity, and the remaining unexplained cases can largely be explained by mutations or low miRNA abundance.

Decreased Expression of Programmed Death Ligand-L1 by Seven in Absentia Homolog 2 in Cholangiocarcinoma Enhances T-Cell-Mediated Antitumor Activity

N6-methyladenosine (m6A) has been reported as an important mechanism of post-transcriptional regulation. Programmed death ligand 1 (PD-L1) is a primary immune inhibitory molecule expressed on tumor cells that promotes immune evasion. In addition, seven in absentia homolog 2 (Siah2), a RING E3 ubiquitin ligase, has been involved in tumorigenesis and cancer progression. However, the role of m6A-METTL14-Siah2-PD-L1 axis in immunotherapy remains to be elucidated. In this study, we showed that METTL14, a component of the m⁶A methyltransferase complex, induced Siah2 expression in cholangiocarcinoma (CCA). METTL14 was shown to enrich m⁶A modifications in the 3'UTR region of the Siah2 mRNA, thereby promoting its degradation in an YTHDF2-dependent manner. Furthermore, co-immunoprecipitation experiments demonstrated that Siah2 interacted with PD-L1 by promoting its K63-linked ubiquitination. We also observed that in vitro and in vivo Siah2 knockdown inhibited T cells expansion and cytotoxicity by sustaining tumor cell PD-L1 expression. The METTL14-Siah2-PD-L1-regulating axis was further confirmed in human CCA specimens. Analysis of specimens from patients receiving anti-PD1 immunotherapy suggested that tumors with low Siah2 levels were more sensitive to anti-PD1 immunotherapy. Taken together, our results evidenced a new regulatory mechanism of Siah2 by METTL14-induced mRNA epigenetic modification and the potential role of Siah2 in cancer immunotherapy.

Elevated Baseline Serum PD-L1 Level May Predict Poor Outcomes from Breast Cancer in African-American and Hispanic Women

BACKGROUND

The therapeutic targeting of PD-1/PD-L1 has shown clinical efficacy in treating metastatic breast cancer. We investigated the clinical significance of measuring serum PD-L1 levels in African-American and Hispanic women with breast cancer.

METHODS

PD-L1 levels were measured with the ELISA method from the serum samples of 244 African-Americans and Hispanics with breast cancer and 155 women without cancers. The levels of INFα2 and TNFα were measured with a Luminex multiplex assay. The protein levels of pAkt and CD44/CD24 in tumor cells were tested with immunohistochemistry analysis. Cox regression was used to assess the predicting role of serum PD-L1 for disease-free survival (DFS).

RESULTS

PD-L1 levels were significantly elevated in breast cancer cases compared to non-cancer cases. The high PD-L1 levels were associated with HER2-positive and triple-negative breast cancer. PD-L1 level independently predicted DFS in both African-American and Hispanic women. The evaluated PD-L1 level was found to be associated with high IFNα2 and TNFα in breast cancer patients.

CONCLUSIONS

PD-L1 serum levels can predict DFS in African American and Hispanic women with breast cancer. Furthermore, a high level of PD-L1 is more likely to be associated with tumor loss PTEN and the activation of Akt or with breast cancer cells expressing CD44high/CD24low. Further validation studies are needed to determine if PD-L1 could serve as a biomarker for patient selection for anti-PD-L1 therapy and assess treatment outcomes.

Emerging Role of PD-1/PD-L1 Inhibitors in Chronic Liver Diseases

Programmed cell death protein 1 (PD-1)/PD-ligand (L)1, the immune checkpoint inhibitors have emerged as a promising strategy for the treatment of various diseases including chronic liver diseases (CLDs) such as hepatitis, liver injury and hepatocellular carcinoma (HCC). The role of PD-1/PD-L1 has been widely inspected in the treatment of viral hepatitis and HCC. PD-1 is known to play a crucial role in inhibiting immunological responses and stimulates self-tolerance by regulating the T-cell activity. Further, it promotes apoptosis of antigen-specific T-cells while preventing apoptosis of Treg cells. PD-L1 is a trans-membrane protein which is recognized as a co-inhibitory factor of immunological responses. Both, PD-1 and PD-L1 function together to downregulate the proliferation of PD-1 positive cells, suppress the expression of cytokines and stimulate apoptosis. Owing to the importance of PD-1/PD-L1 signaling, this review aims to summarize the potential of PD-1/PD-L1 inhibitors in CLDs along with toxicities associated with them. We have enlisted some of the important roles of PD-1/PD-L1 in CLDs, the clinically approved products and the pipelines of drugs under clinical evaluation.

Serological assessment of collagen fragments and tumor fibrosis may guide immune checkpoint inhibitor therapy

Despite the overall clinical success of immune checkpoint inhibitors (ICIs) for treating patients with solid tumors, a large number of patients do not benefit from this approach. Consequently, there is a need for predictive biomarkers. The most prevalent biomarkers such as PD-L1 expression and tumor mutational burden (TMB) do not reliably predict response to ICIs across different solid tumor types suggesting that a broader view of regulating factors in the tumor microenvironment is needed. Emerging evidence indicates that one central common denominator of resistance to ICIs may be fibrotic activity characterized by extracellular matrix (ECM) and collagen production by cancer-associated fibroblasts (CAFs). A fibroblast-and collagen-rich stroma attenuates immunotherapy response by contributing to inhibition and exclusion of T cells. Here we review opportunities and limitations in the utilization of the most prevalent biomarkers for ICIs and elaborate on the unique opportunities with biomarkers originating from the activated fibroblasts producing an impermeable ECM. We propose that ECM and collagen biomarkers measured non-invasively may be a novel and practical approach to optimize treatment strategies and improve patient selection for ICI therapy.

Overcoming Resistance to Immunotherapy in Advanced Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans, and is now responsible for as many deaths as melanoma. Immunotherapy has changed the therapeutic landscape of advanced CSCC after the FDA approval of anti-PD1 molecules for the treatment of locally advanced and metastatic CSCC. However, roughly 50% of patients will not respond to this systemic treatment and even those who do respond can develop resistance over time. The etiologies of primary and secondary resistance to immunotherapy involve changes in the neoplastic cells and the tumor microenvironment. Indirect modulation of immune system activation with new therapies, such as vaccines, oncolytic viruses, and new immunotherapeutic agents, and direct modulation of tumor immunogenicity using other systemic treatments or radiotherapy are now under evaluation in combined regimens. The identification of predictors of response is an important area of research. In this review, we focus on the features associated with the response to immunotherapy, and the evaluation of combination treatments and new molecules, a more thorough knowledge of which is likely to improve the survival of patients with advanced CSCC.

The clinical significance of tertiary lymphoid structure and its relationship with peripheral blood characteristics in patients with surgically resected non-small cell lung cancer: a single-center, retrospective study

INTRODUCTION

The presence of tertiary lymphoid structure (TLS) in tumor tissues has been reported to be a factor associated with a good prognosis in several types of cancers. However, the relationship between TLS formation and peripheral blood findings remains unclear. The purposes of the study were to evaluate the effect of the presence of TLS on survival and determine the peripheral blood characteristics associated with TLS formation in non-small cell lung cancer (NSCLC) patients.

METHODS

A total of 147 consecutive NSCLC patients who underwent lung resection at Fukushima Medical University Hospital between 2013 and 2017 were enrolled. TLS expression was evaluated, and the relationships between clinical parameters and outcomes were analyzed. Peripheral blood mononuclear cells (PBMCs) were further analyzed by mass cytometry to characterize the TLS-positive microenvironment.

RESULTS

Forty-six patients had high TLS expression, and the remaining 101 patients had low TLS expression. In stage II to IV patients (n = 35), disease-free survival was longer in the high TLS expression group (p = 0.027). A low neutrophil to lymphocyte ratio (NLR) < 2.75 in the peripheral blood was associated with high TLS expression (p = 0.003). Citrus analysis after mass cytometry assay showed that the number of cells expressing HLA-DR and CD9 in PBMCs was lower in the high TLS expression group.

CONCLUSION

High TLS expression is associated with a good prognosis after surgery in stage II and III NSCLC patients. In the peripheral blood, a low NLR and few antigen-presenting cells indicate the presence of TLS in the tumor microenvironment.

Can evaluation of mismatch repair defect and TILs increase the number of triple-negative breast cancer patients eligible for immunotherapy?

BACKGROUND

Programmed-cell-death-ligand 1 (PD-L1) inhibitor treatment is approved for metastatic/recurrent, PD-L1 positive, triple-negative breast cancer (TNBC) and solid tumors with mismatch repair (MMR) defect regardless of PD-L1 status. The analytical validity of PD-L1 has been questioned and adding evaluation of tumor-infiltrating lymphocytes (TILs) may identify patients likely to respond to immunotherapy. We investigated the association between MMR-deficiency and PD-L1 in TNBC; aiming to identify PD-L1 negative, TNBC patients that may be candidates for anti-PD-L1 immunotherapy.

METHODOLOGY

Paraffin-embedded tumor material from 44 TNBC patients was included. In 38 cases, immunohistochemical-staining´s on whole-slide sections were successful for all four MMR proteins (MSH2, MSH6, MLH1 and PMS2) and PD-L1 in 36 cases. MMR-status was categorized as positive (pMMR), heterogeneous (hMMR) or deficient (dMMR). Tumor-infiltrating lymphocytes (TILs) were evaluated on H&E sections.

RESULTS

MMR stainings showed substantial intratumor heterogeneity. Four of 38 cases (11%) were recorded as dMMR with loss of ≥ 1 MMR-protein and 19 cases (50%) showed heterogeneous expression or partial loss (hMMR) of ≥ 1 MMR-protein. Three of 22 PD-L1 negative cases were dMMR (14%) and ten cases hMMR (45%). 16 of 22 PD-L1 negative cases (73%) showed high TILs.

CONCLUSIONS

A substantial proportion of PD-L1 negative, TNBC patients showed complete/partial loss of MMR and/or high TILs indicating that supplementing PD-L1 examination with these biomarkers may identify TNBC-patients that may be selected for immunotherapy.

Synthesis and Preclinical Evaluation of a 68Ga-Labeled Adnectin, 68Ga-BMS-986192, as a PET Agent for Imaging PD-L1 Expression

Blocking the interaction of the immune checkpoint molecule programmed cell death protein-1 and its ligand, PD-L1, using specific antibodies has been a major breakthrough for immune oncology. Whole-body PD-L1 expression PET imaging may potentially allow for a better prediction of response to programmed cell death protein-1-targeted therapies. Imaging of PD-L1 expression is feasible by PET with the adnectin protein 18F-BMS-986192. However, radiofluorination of proteins such as BMS-986192 remains complex and labeling yields are low. The goal of this study was therefore the development and preclinical evaluation of a 68Ga-labeled adnectin protein (68Ga-BMS-986192) to facilitate clinical trials. Methods:68Ga labeling of DOTA-conjugated adnectin (BXA-206362) was performed in NaOAc-buffer at pH 5.5 (50°C, 15 min). In vitro stability in human serum at 37°C was analyzed using radio-thin layer chromatography and radio-high-performance liquid chromatography. PD-L1 binding assays were performed using the transduced PD-L1-expressing lymphoma cell line U-698-M and wild-type U-698-M cells as a negative control. Immunohistochemical staining studies, biodistribution studies, and small-animal PET studies of 68Ga-BMS-986192 were performed using PD-L1-positive and PD-L1-negative U-698-M-bearing NSG mice. Results:68Ga-BMS-986192 was obtained with quantitative radiochemical yields of more than 97% and with high radiochemical purity. In vitro stability in human serum was at least 95% after 4 h of incubation. High and specific binding of 68Ga-BMS-986192 to human PD-L1-expressing cancer cells was confirmed, which closely correlates with the respective PD-L1 expression level determined by flow cytometry and immunohistochemistry staining. In vivo, 68Ga-BMS-986192 uptake was high at 1 h after injection in PD-L1-positive tumors (9.0 ± 2.1 percentage injected dose [%ID]/g) and kidneys (56.9 ± 9.2 %ID/g), with negligible uptake in other tissues. PD-L1-negative tumors demonstrated only background uptake of radioactivity (0.6 ± 0.1 %ID/g). Coinjection of an excess of unlabeled adnectin reduced tumor uptake of PD-L1 by more than 80%. Conclusion:68Ga-BMS-986192 enables easy radiosynthesis and shows excellent in vitro and in vivo PD-L1-targeting characteristics. The high tumor uptake combined with low background accumulation at early imaging time points demonstrates the feasibility of 68Ga-BMS-986192 for imaging of PD-L1 expression in tumors and is encouraging for further clinical applications of PD-L1 ligands.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of breast cancer

Breast cancer has historically been a disease for which immunotherapy was largely unavailable. Recently, the use of immune checkpoint inhibitors (ICIs) in combination with chemotherapy for the treatment of advanced/metastatic triple-negative breast cancer (TNBC) has demonstrated efficacy, including longer progression-free survival and increased overall survival in subsets of patients. Based on clinical benefit in randomized trials, ICIs in combination with chemotherapy for the treatment of some patients with advanced/metastatic TNBC have been approved by the United States (US) Food and Drug Administration (FDA), expanding options for patients. Ongoing questions remain, however, about the optimal chemotherapy backbone for immunotherapy, appropriate biomarker-based selection of patients for treatment, the optimal strategy for immunotherapy treatment in earlier stage disease, and potential use in histological subtypes other than TNBC. To provide guidance to the oncology community on these and other important concerns, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew upon the published literature as well as their clinical experience to develop recommendations for healthcare professionals on these important aspects of immunotherapeutic treatment for breast cancer, including diagnostic testing, treatment planning, immune-related adverse events (irAEs), and patient quality of life (QOL) considerations. The evidence-based and consensus-based recommendations in this CPG are intended to give guidance to cancer care providers treating patients with breast cancer.

M6A Demethylase ALKBH5 Regulates PD-L1 Expression and Tumor Immunoenvironment in Intrahepatic Cholangiocarcinoma

N6-methyladenosine (m6A) has been reported as an important mechanism of post-transcriptional regulation. Programmed death-ligand 1 (PD-L1) is a primary immune inhibitory molecule expressed on tumor cells that promotes immune evasion. Here we report ALKBH5 as an important m6A demethylase that orchestrates PD-L1 expression in intrahepatic cholangiocarcinoma (ICC). Regulation of PD-L1 expression by ALKBH5 was confirmed in human ICC cell lines. Sequencing of the m6A methylome identified PD-L1 mRNA as a direct target of m6A modification whose levels were regulated by ALKBH5. Furthermore, ALKBH5 and PD-L1 mRNA were shown to interact. ALKBH5 deficiency enriched m6A modification in the 3'UTR region of PD-L1 mRNA, thereby promoting its degradation in a YTHDF2-dependent manner. In vitro and in vivo, tumor-intrinsic ALKBH5 inhibited the expansion and cytotoxicity of T cells by sustaining tumor cell PD-L1 expression. The ALKBH5-PD-L1-regulating axis was further confirmed in human ICC specimens. Single-cell mass cytometry analysis unveiled a complex role of ALKBH5 in the tumor immune microenvironment by promoting the expression of PD-L1 on monocytes/macrophages and decreasing the infiltration of myeloid-derived suppressor-like cells. Analysis of specimens from patients receiving anti-PD1 immunotherapy suggested that tumors with strong nuclear expression patterns of ALKBH5 are more sensitive to anti-PD1 immunotherapy. Collectively, these results describe a new regulatory mechanism of PD-L1 by mRNA epigenetic modification by ALKBH5 and the potential role of ALKBH5 in immunotherapy response, which might provide insights for cancer immunotherapies.

The Next-Generation of Combination Cancer Immunotherapy: Epigenetic Immunomodulators Transmogrify Immune Training to Enhance Immunotherapy

Cancer immunotherapy harnesses the immune system by targeting tumor cells that express antigens recognized by immune system cells, thus leading to tumor rejection. These tumor-associated antigens include tumor-specific shared antigens, differentiation antigens, protein products of mutated genes and rearrangements unique to tumor cells, overexpressed tissue-specific antigens, and exogenous viral proteins. However, the development of effective therapeutic approaches has proven difficult, mainly because these tumor antigens are shielded, and cells primarily express self-derived antigens. Despite innovative and notable advances in immunotherapy, challenges associated with variable patient response rates and efficacy on select tumors minimize the overall effectiveness of immunotherapy. Variations observed in response rates to immunotherapy are due to multiple factors, including adaptative resistance, competency, and a diversity of individual immune systems, including cancer stem cells in the tumor microenvironment, composition of the gut microbiota, and broad limitations of current immunotherapeutic approaches. New approaches are positioned to improve the immune response and increase the efficacy of immunotherapies, highlighting the challenges that the current global COVID-19 pandemic places on the present state of immunotherapy.

Effects of 1p/19q Codeletion on Immune Phenotype in Low Grade Glioma

Background: Chromosome 1p/19q codeletion is one of the most important genetic alterations for low grade gliomas (LGGs), and patients with 1p/19q codeletion have significantly prolonged survival compared to those without the codeletion. And the tumor immune microenvironment also plays a vital role in the tumor progression and prognosis. However, the effect of 1p/19q codeletion on the tumor immune microenvironment in LGGs is unclear. Methods: Immune cell infiltration of 281 LGGs from The Cancer Genome Atlas (TCGA) and 543 LGGs from the Chinese Glioma Genome Atlas (CGGA) were analyzed for immune cell infiltration through three bioinformatics tools: ESTIMATE algorithm, TIMER, and xCell. The infiltrating level of immune cells and expression of immune checkpoint genes were compared between different groups classified by 1p/19q codeletion and IDH (isocitrate dehydrogenase) mutation status. The differential biological processes and signaling pathways were evaluated through Gene Set Enrichment Analysis (GSEA). Correlations were analyzed using Spearman correlation. Results: 1p/19q codeletion was associated with immune-related biological processes in LGGs. The infiltrating level of multiple kinds of immune cells and expression of immune checkpoint genes were significantly lower in 1p/19q codeletion LGGs compared to 1p/19q non-codeletion cohorts. There are 127 immune-related genes on chromosome 1p or 19q, such as TGFB1, JAK1, and CSF1. The mRNA expression of these genes was positively correlated with their DNA copy number. These genes are distributed in multiple immune categories, such as chemokines/cytokines, TGF-β family members, and TNF family members, regulating immune cell infiltration and expression of the immune checkpoint genes in tumors. Conclusion: Our results indicated that 1p/19q codeletion status is closely associated with the immunosuppressive microenvironment in LGGs. LGGs with 1p/19q codeletion display less immune cell infiltration and lower expression of immune checkpoint genes than 1p/19q non-codeletion cases. Mechanistically, this may be, at least in part, due to the deletion of copy number of immune-related genes in LGGs with 1p/19q codeletion. Our findings may be relevant to investigate immune evasion in LGGs and contribute to the design of immunotherapeutic strategies for patients with LGGs.

Selecting the optimal immunotherapy regimen in driver-negative metastatic NSCLC

The treatment landscape of driver-negative non-small-cell lung cancer (NSCLC) is rapidly evolving. Immune-checkpoint inhibitors, specifically those targeting PD-1 or PD-L1, have demonstrated durable efficacy in a subset of patients with NSCLC, and these agents have become the cornerstone of first-line therapy. Approved immunotherapeutic strategies for treatment-naive patients now include monotherapy, immunotherapy-exclusive regimens or chemotherapy-immunotherapy combinations. Decision making in this space is complex given the absence of head-to-head prospective comparisons, although a thorough analysis of long-term efficacy and safety data from pivotal clinical trials can provide insight into the optimal management of each subset of patients. Indeed, histological subtype and the extent of tumour cell PD-L1 expression are paramount to regimen selection, although other clinicopathological factors and patient preferences might also be relevant in certain scenarios. Finally, several emerging biomarkers and novel therapeutic strategies are currently under investigation, and these might further refine the current treatment paradigm. In this Review, we discuss the current treatment landscape and detail our approach to first-line immunotherapy regimen selection for patients with advanced-stage, driver-negative NSCLC.

TGF-β inhibition can overcome cancer primary resistance to PD-1 blockade: A mathematical model

Immune checkpoint inhibitors have demonstrated, over the recent years, impressive clinical response in cancer patients, but some patients do not respond at all to checkpoint blockade, exhibiting primary resistance. Primary resistance to PD-1 blockade is reported to occur under conditions of immunosuppressive tumor environment, a condition caused by myeloid derived suppressor cells (MDSCs), and by T cells exclusion, due to increased level of T regulatory cells (Tregs). Since TGF-β activates Tregs, TGF-β inhibitor may overcome primary resistance to anti-PD-1. Indeed, recent mice experiments show that combining anti-PD-1 with anti-TGF-β yields significant therapeutic improvements compared to anti-TGF-β alone. The present paper introduces two cancer-specific parameters and, correspondingly, develops a mathematical model which explains how primary resistance to PD-1 blockade occurs, in terms of the two cancer-specific parameters, and how, in combination with anti-TGF-β, anti-PD-1 provides significant benefits. The model is represented by a system of partial differential equations and the simulations are in agreement with the recent mice experiments. In some cancer patients, treatment with anti-PD-1 results in rapid progression of the disease, known as hyperprogression disease (HPD). The mathematical model can also explain how this situation arises, and it predicts that HPD may be reversed by combining anti-TGF-β to anti-PD-1. The model is used to demonstrate how the two cancer-specific parameters may serve as biomarkers in predicting the efficacy of combination therapy with PD-1 and TGF-β inhibitors.

Cell Therapy With TILs: Training and Taming T Cells to Fight Cancer

The rationale behind cancer immunotherapy is based on the unequivocal demonstration that the immune system plays an important role in limiting cancer initiation and progression. Adoptive cell therapy (ACT) is a form of cancer immunotherapy that utilizes a patient’s own immune cells to find and eliminate tumor cells, however, donor immune cells can also be employed in some cases. Here, we focus on T lymphocyte (T cell)-based cancer immunotherapies that have gained significant attention after initial discoveries that graft-versus-tumor responses were mediated by T cells. Accumulating knowledge of T cell development and function coupled with advancements in genetics and data science has enabled the use of a patient’s own (autologous) T cells for ACT (TIL ACTs). In TIL ACT, tumor-infiltrating lymphocytes (TILs) are collected from resected tumor material, enhanced and expanded ex-vivo, and delivered back to the patient as therapeutic agents. ACT with TILs has been shown to cause objective tumor regression in several types of cancers including melanoma, cervical squamous cell carcinoma, and cholangiocarcinoma. In this review, we provide a brief history of TIL ACT and discuss the current state of TIL ACT clinical development in solid tumors. We also discuss the niche of TIL ACT in the current cancer therapy landscape and potential strategies for patient selection.

Clinical and Hematological Predictors of High-Grade Immune-Related Adverse Events Associated With Immune Checkpoint Inhibitors

Background

Life-threatening immune-related adverse events (irAEs) that require hospital admission are not uncommon in patients treated with immune checkpoint inhibitors (ICIs). The clinical and hematological parameters are attractive biomarkers as potential predictors of irAE.

Methods

This is a retrospective study of patients with melanoma and lung cancer treated with ICIs between 2015 and 2019 at the University of South Alabama Mitchell Cancer Institute. Fisher’s exact test, Pearson Chi-squared test, log-rank test, and Cox proportional hazard model were used to evaluate clinical and hematological parameters as possible predictors of irAE.

Results

The cohort consisted of 160 patients treated with at least two doses of ICI, of which 54 (33.8%) patients had melanoma and 106 (66.3%) had lung cancer. Incidence of irAE did not have any bearing on the overall survival (OS) or progression-free survival (PFS) of the cohort. The clinical factors associated with irAE were dual-agent therapy (ipilimumab/nivolumab combination) and high disease burden (≥ 2 metastatic sites). The irAE-group had a lower mean platelet-to-lymphocyte ration (PLR, 200 vs. 257, P = 0.04). Although not statistically significant at the level of 0.05, other factors such as type of cancer (lung cancer > melanoma (P = 0.06)), stage at treatment (stage IV > stage II and III disease (P = 0.06)), and higher absolute lymphocyte counts (P = 0.07) showed a considerable association with irAE and warrants further review with different patient data.

Conclusions

Irrespective of ICI used to treat lung cancer and melanoma, patients with high disease burden and dual-agent ICI therapy were more prone to irAE. The only hematological parameter that may predict the incidence of irAE is low baseline PLR.

A cytokine receptor-masked IL2 prodrug selectively activates tumor-infiltrating lymphocytes for potent antitumor therapy

As a potent lymphocyte activator, interleukin-2 (IL-2) is an FDA-approved treatment for multiple metastatic cancers. However, its clinical use is limited by short half-life, low potency, and severe in vivo toxicity. Current IL-2 engineering strategies exhibit evidence of peripheral cytotoxicity. Here, we address these issues by engineering an IL-2 prodrug (ProIL2). We mask the activity of a CD8 T cell-preferential IL-2 mutein/Fc fusion protein with IL2 receptor beta linked to a tumor-associated protease substrate. ProIL2 restores activity after cleavage by tumor-associated enzymes, and preferentially activates inside tumors, where it expands antigen-specific CD8 T cells. This significantly reduces IL-2 toxicity and mortality without compromising antitumor efficacy. ProIL2 also overcomes resistance of cancers to immune checkpoint blockade. Lastly, neoadjuvant ProIL2 treatment can eliminate metastatic cancer through an abscopal effect. Taken together, our approach presents an effective tumor targeting therapy with reduced toxicity.

Human leukocyte antigen I is significantly downregulated in patients with myxoid liposarcomas

The characteristics of the tumor immune microenvironment remains unclear in liposarcomas, and here we aimed to determine the prognostic impact of the tumor immune microenvironment across separate liposarcomas subtypes. A total of 70 liposarcoma patients with three subtypes: myxoid liposarcoma (n = 45), dedifferentiated liposarcoma (n = 17), and pleomorphic liposarcoma (n = 8) were enrolled. The presence of tumor infiltrating lymphocytes (CD4+ , CD8+ , FOXP3+ lymphocytes) and CD163+ macrophages and expression of HLA class I and PD-L1 were assessed by immunohistochemistry in the diagnostic samples; overall survival and progression-free survival were estimated from outcome data. For infiltrating lymphocytes and macrophages, dedifferentiated liposarcoma and pleomorphic liposarcoma patients had a significantly higher number than myxoid liposarcoma patients. While myxoid liposarcoma patients with a high number of macrophages were associated with worse overall and progression-free survival, dedifferentiated liposarcoma patients with high macrophage numbers showed a trend toward favorable prognosis. Expression of HLA class I was negative in 35 of 45 (77.8%) myxoid liposarcoma tumors, whereas all dedifferentiated liposarcoma and pleomorphic liposarcoma tumors expressed HLA class I. The subset of myxoid liposarcoma patients with high HLA class I expression had significantly poor overall and progression-free survival, while dedifferentiated liposarcoma patients with high HLA class I expression tended to have favorable outcomes. Only four of 17 (23.5%) dedifferentiated liposarcomas, two of eight (25%) pleomorphic liposarcomas, and no myxoid liposarcoma tumors expressed PD-L1. Our results demonstrate the unique immune microenvironment of myxoid liposarcomas compared to other subtypes of liposarcomas, suggesting that the approach for immunotherapy in liposarcomas should be based on subtype.