Immunotherapy and lung cytopathology: Overview and possibilities

Immunotherapy has become a promising cancer treatment in the past decade, and IHC is the most commonly used testing method for PDL-1/PD1 evaluation. In general, PD-L1 assays can be performed on both FFPE specimens and cytological samples. However, their use on smears is not yet well-established or validated. Nowadays, digital images and advanced algorithms can aid in interpreting PD-L1 in cytological samples. Understanding the immune environment of non-small cell lung cancer (NSCLC) is critical in developing successful anticancer immunotherapies. The use of a multiplexed immunofluorescence (mIF) assay on cytological samples obtained through minimally invasive methods appears to be a viable option for investigating the immune environment of NSCLC. This review aims to briefly summarize the knowledge of the role of cytopathology in the analysis of PD-L1 by immunocytochemistry (ICC) and future directions of cytopathology in the immunotherapy setting.

Mutation profile and programmed death ligand 1 status of patients with non-small cell lung cancer diagnosed with "adenocarcinoma" and "non-small cell carcinoma favor adenocarcinoma"

BACKGROUND

The terminology for lung cancer diagnosis in small biopsies was adopted in the 2015 World Health Organization classification. If non-small cell lung cancer (NSCLC) has no clear adenocarcinoma (AD) or squamous cell carcinoma morphology, the tumor is further classified based on mucin or immunohistochemical staining as NSCLC favor AD (NFAD), NSCLC favor squamous cell carcinoma, or NSCLC not otherwise specified. Since this new term was defined, the difference between AD and NFAD has not yet been fully explored. This study aimed to examine the differences in clinical background, gene alteration frequency, and programmed death ligand 1 (PD-L1) expression.

METHODS

We included patients diagnosed with AD or NFAD with small samples, and who underwent testing with the Oncomine Dx target test between August 2019 and April 2023 in Kanagawa Cancer Center.

RESULTS

This study comprised 268 patients. A total of 96 patients underwent surgery after AD or NFAD diagnosis. The clinical stage was more advanced and pathological N0 was lower in NFAD than in AD. The pathology of the surgical specimens revealed that solid predominant AD was significantly more common in NFAD than in AD (p < 0.001). In both AD and NFAD, EGFR mutation was the most frequent gene alteration, followed by KRAS mutation. The frequency of EGFR mutations was significantly higher in AD than in NFAD. PD-L1 expression was significantly higher in NFAD than in AD (p < 0.001).

CONCLUSION

This study shows a clear difference between AD and NFAD in terms of cancer progression, pathological features of the main tumor, genetic characteristics, and PD-L1 expression.

PD-L1 and AKT Overexpressing Adipose-Derived Mesenchymal Stem Cells Enhance Myocardial Protection by Upregulating CD25+ T Cells in Acute Myocardial Infarction Rat Model

This study explores the synergistic impact of Programmed Death Ligand 1 (PD-L1) and Protein Kinase B (Akt) overexpression in adipose-derived mesenchymal stem cells (AdMSCs) for ameliorating cardiac dysfunction after myocardial infarction (MI). Post-MI adult Wistar rats were allocated into four groups: sham, MI, ADMSC treatment, and ADMSCs overexpressed with PD-L1 and Akt (AdMSC-PDL1-Akt) treatment. MI was induced via left anterior descending coronary artery ligation, followed by intramyocardial AdMSC injections. Over four weeks, cardiac functionality and structural integrity were assessed using pressure-volume analysis, infarct size measurement, and immunohistochemistry. AdMSC-PDL1-Akt exhibited enhanced resistance to reactive oxygen species (ROS) in vitro and ameliorated MI-induced contractile dysfunction in vivo by improving the end-systolic pressure-volume relationship and preload-recruitable stroke work, together with attenuating infarct size. Molecular analyses revealed substantial mitigation in caspase3 and nuclear factor-κB upregulation in MI hearts within the AdMSC-PDL1-Akt group. Mechanistically, AdMSC-PDL1-Akt fostered the differentiation of normal T cells into CD25+ regulatory T cells in vitro, aligning with in vivo upregulation of CD25 in AdMSC-PDL1-Akt-treated rats. Collectively, PD-L1 and Akt overexpression in AdMSCs bolsters resistance to ROS-mediated apoptosis in vitro and enhances myocardial protective efficacy against MI-induced dysfunction, potentially via T-cell modulation, underscoring a promising therapeutic strategy for myocardial ischemic injuries.

A case of discordant histology and expression of programmed death ligand 1 between primary tumor and brain metastases in adenosquamous carcinoma of the lung

A patient presented with vomiting and gait disturbance. Investigation revealed a single cerebellar tumor and another tumor in the upper lobe of the left lung. Based on the severe vomiting and gait disturbance, we removed the cerebellar tumor first, achieving resolution of symptoms. The cerebellar tumor was pathologically diagnosed as metastatic lung adenocarcinoma. No other metastases were identified, including in the mediastinal lymph nodes. We therefore resected the primary lung tumor. On final pathological analysis, the tumor in the upper lobe of the left lung was diagnosed as adenosquamous carcinoma with no lymph node metastasis. PD-L1 expression was low in the primary lung adenosquamous carcinoma and high in the cerebellar metastasis. Furthermore, both tumors were KRASG12C -positive. Tumor PD-L1 expression is considered important for immune escape. In this case, adenocarcinoma cells in the primary adenosquamous carcinoma may have migrated to form a cerebellar metastasis. In advanced lung cancer, tumor growth may be observed in some lesions even when many other lesions are controlled by chemo- or immunotherapy. Biopsy to confirm histology and PD-L1 expression is worth considering, depending on the location of the metastases and the invasiveness of the biopsy procedure.

Comprehensive Review: Unveiling the Pro-Oncogenic Roles of IL-1ß and PD-1/PD-L1 in NSCLC Development and Targeting Their Pathways for Clinical Management

In the past decade, targeted therapies for solid tumors, including non-small cell lung cancer (NSCLC), have advanced significantly, offering tailored treatment options for patients. However, individuals without targetable mutations pose a clinical challenge, as they may not respond to standard treatments like immune-checkpoint inhibitors (ICIs) and novel targeted therapies. While the mechanism of action of ICIs seems promising, the lack of a robust response limits their widespread use. Although the expression levels of programmed death ligand 1 (PD-L1) on tumor cells are used to predict ICI response, identifying new biomarkers, particularly those associated with the tumor microenvironment (TME), is crucial to address this unmet need. Recently, inflammatory cytokines such as interleukin-1 beta (IL-1β) have emerged as a key area of focus and hold significant potential implications for future clinical practice. Combinatorial approaches of IL-1β inhibitors and ICIs may provide a potential therapeutic modality for NSCLC patients without targetable mutations. Recent advancements in our understanding of the intricate relationship between inflammation and oncogenesis, particularly involving the IL-1β/PD-1/PD-L1 pathway, have shed light on their application in lung cancer development and clinical outcomes of patients. Targeting these pathways in cancers like NSCLC holds immense potential to revolutionize cancer treatment, particularly for patients lacking targetable genetic mutations. However, despite these promising prospects, there remain certain aspects of this pathway that require further investigation, particularly regarding treatment resistance. Therefore, the objective of this review is to delve into the role of IL-1β in NSCLC, its participation in inflammatory pathways, and its intricate crosstalk with the PD-1/PD-L1 pathway. Additionally, we aim to explore the potential of IL-1β as a therapeutic target for NSCLC treatment.

Efficacy of ICI-based treatment in advanced NSCLC patients with PD-L1≥50% who developed EGFR-TKI resistance

Introduction

Platinum-based chemotherapy is still the standard of care for Epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC) patients after developing EGFR-TKI resistance. However, no study focusing on the role of immuno checkpoint inhibitor (ICI) based treatments for EGFR mutated NSCLC patients who carried programmed death ligand 1 (PD-L1) tumor proportion score (TPS) greater than 50% progressed after EGFR-TKI therapy. In this study, we retrospectively investigated the outcomes of ICI-based treatments for EGFR mutated NSCLC patients carried PD-L1 TPS≥50% after developing EGFR-TKI resistance and to explore the population that may benefited from ICI-based treatment.

Methods

We retrospectively collected data of advanced NSCLC patients with EGFR mutations and PD-L1 TPS≥50% who have failed prior EGFR-TKI therapies without T790M mutation at Shanghai Chest Hospital between January 2018 and June 2021. Progression-free survival (PFS) and overall survival (OS) were utilized to evaluate the outcomes of this study.

Results

A total of 146 patients were included. Up to June 20th, 2022, median follow-up was 36.7 months (IQR, 12.5-44.2 months). Among the population, 66 patients (45.2%) received chemotherapy, the remaning (54.8%) received ICI-based treatment, including 56 patients(70.0%) received ICI combined with chemotherapy (IC) and 24 patients (30.0%) received ICI monotherapy (IM). In IC group,31 patients received ICI combined with chemotherapy,19 patients received ICI combined with antiangiogenic therapy and remaing received ICI combined with chemotherapy and antiangiogenic therapy. Survival analysis shown that patients who received ICI-based treatment had better progress-free survival (PFS) and overall survival (OS) compared with those treated with other therapy (median PFS, 10.0 vs. 4.0 months, P<0.001; median OS, 39.5 vs. 24.2 months, P<0.001). What's more, patients who treated with IC treatment had a superior survival time than those received IM treatment (median PFS, 10.3 vs. 7.0 months, P<0.001; median OS, 41.6 vs. 32.4 months, P<0.001). Subgroup analysis found that the PFS and OS benefit of IC was evident in all subgroups.

Conclusions

For advanced NSCLC patients with EGFR mutations and PD-L1 TPS≥50% who have failed prior EGFR-TKI therapies without T790M mutation, ICI-based treatment could provide a more favorable survival than classical chemotherapy. What' s more, compared with ICI monotherapy, ICI combined with chemotherapy seems to be the preferred treatment.

A Cascade-Targeted Enzyme-Instructed Peptide Self-Assembly Strategy for Cancer Immunotherapy through Boosting Immunogenic Cell Death

Immunogenic cell death (ICD) approaches by encumbering mitochondrial functions provide great promise for the treatment of malignant tumors, but these kinds of ICD strategies are still in their infancy. Here, one multifunctional drug-loaded, cascade-targeted, and enzyme-instructed self-assembling peptide nanomedicine (Comp. 4) for ICD-based cancer therapy is constructed. Comp. 4 consists of 1) lonidamine (LND) that specifically interferes with mitochondrial functions; 2) a programmed death ligand 1 (PD-L1) binding peptide sequence (NTYYEDQG) and a mitochondria-specific motif (triphenylphosphonium, TPP) that can sequentially control the cell membrane and mitochondria targeting capacities, respectively; and 3) a -G^D F^D Fp^D Y- assembly core to in situ organize peptide assemblies responsive to alkaline phosphatase (ALP). Comp. 4 demonstrates noticeable structural and morphological transformations in the presence of ALP and produces peptide assemblies in mouse colon cancer cells (CT26) with high expressions of both ALP and PD-L1. Moreover, the presence of PD-L1- and mitochondria-specific motifs can assist Comp. 4 for effective endocytosis and endosomal escape, forming peptide assemblies and delivering LND into mitochondria. Consequently, Comp. 4 shows superior capacities to in vivo induce abundant mitochondrial oxidative stress, provoke robust ICD responses, and produce an immunogenic tumor microenvironment, successfully inhibiting CT26 tumor growth by eliciting a systemic ICD-based antitumor immunity.

BRAF RNA is prognostic and widely expressed in lung adenocarcinoma

Background

BRAF is a critical member of proliferation pathways in cancer, and a mutation is present in only 2-4% of lung adenocarcinomas (LADC). There is no data available on the expression pattern of BRAF RNA that might result in enhanced signalling and drug resistance.

Methods

LADC tissue samples (n=64) were fixed and processed into paraffin blocks. Tissue microarrays (TMA) were constructed, and RNAScope^® in situ hybridization (ISH) assay was performed for wild-type (WT) BRAF RNA. Apart from pathological assessment of tumor samples (grade, necrosis, vascular involvement and peritumoral infiltration), anti-programmed death ligand 1 (PD-L1) and anti-programmed death 1 (PD-1) immunohistochemistry and validation in public databases [The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA)] were carried out.

Results

WT BRAF RNA is expressed in LADC, with no significant expressional difference between early-stage (I-II) and advanced-stage (III-IV) patients (P=0.317). Never smokers exhibited significantly increased BRAF expression (compared to current and ex-smokers, P<0.01) and tumor necrosis correlated significantly with BRAF expression (P=0.014). PD-L1 expression was assessed on tumor cells and immune cells, PD-1 expression was evaluated on immune cells. There was no significant difference in BRAF RNA expression between tumor cell PD-L1-high vs. low patients (P=0.124), but it was decreased in immune cell PD-L1-high patients (P=0.03). Kaplan-Meier survival analysis showed that high BRAF expression was associated with significantly decreased OS (P<0.01) and was an independent negative prognostic factor according to multivariate Cox hazard regression (P=0.024). TCGA validation cohort confirmed our findings regarding OS in early-stage patients (P=0.034).

Conclusions

We found an increased expression of BRAF RNA in all stages in LADC. High BRAF expression was associated with tumor necrosis, distinct immune checkpoint biology and outcomes. We recommend further evaluating the potential of targeting overexpressed BRAF pathways in LADC.

Evaluation of programmed death ligand 1 expression in cytology to determine eligibility for immune checkpoint inhibitor therapy in patients with head and neck squamous cell carcinoma

BACKGROUND

Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway have recently emerged as a frontline treatment for head and neck squamous cell carcinoma (HNSCC). The evaluation of PD-L1 expression by immunohistochemistry in histologic samples is used to determine the eligibility of patients with HNSCC for immunotherapy. Patients with newly diagnosed HNSCC are frequently diagnosed by fine-needle aspiration (FNA) of lymph nodes with metastatic disease. However, the evaluation of PD-L1 expression with the proposed combined positive score (CPS) has not been well established in cytology specimens.

METHODS

This study retrospectively identified 21 HNSCC patients with a known PD-L1 status from histologic specimens and matched FNA specimens with tumor cells on cell blocks (CBs). The CB sections were stained with a PD-L1 antibody (22C3 clone). All cases were scored with CPS and the tumor proportion score (TPS).

RESULTS

The data showed substantial concordance between cytologic and histologic specimens for CPS (agreement, 76.2%; κ = 0.607) and TPS (agreement, 76.2%; κ = 0.607). With histology used as a reference standard, the positive predictive value was 100% for both CPS and TPS, whereas the negative predictive value was 57.1% for CPS assessments and 50% for TPS assessments.

CONCLUSIONS

PD-L1 expression in HNSCC cytology samples has high concordance with paired histologic samples. PD-L1 CPS evaluation is feasible in HNSCC cytology CBs and can act as a surrogate for determining eligibility for immunotherapy in cases in which a histologic specimen is not readily available.

PD-L1 sustains chronic, cancer cell-intrinsic responses to type I interferon, enhancing resistance to DNA damage

Programmed death ligand 1 (PD-L1), an immune-checkpoint protein expressed on cancer cells, also functions independently of the immune system. We found that PD-L1 inhibits the killing of cancer cells in response to DNA damage in an immune-independent manner by suppressing their acute response to type I interferon (IFN; IFN-I). In addition, PD-L1 plays a critical role in sustaining high levels of constitutive expression in cancer cells of a subset of IFN-induced genes, the IFN-related DNA damage resistance signature (IRDS) which, paradoxically, protects cancer cells. The cyclic GMP-AMP synthase-stimulator of the IFN genes (cGAS-STING) pathway is constitutively activated in a subset of cancer cells in the presence of high levels of PD-L1, thus leading to a constitutive, low level of IFN-β expression, which in turn increases IRDS expression. The constitutive low level of IFN-β expression is critical for the survival of cancer cells addicted to self-produced IFN-β. Our study reveals immune-independent functions of PD-L1 that inhibit cytotoxic acute responses to IFN-I and promote protective IRDS expression by supporting protective chronic IFN-I responses, both of which enhance the resistance of cancer cells to DNA damage.

Narrative review of emerging roles for AKT-mTOR signaling in cancer radioimmunotherapy

Objective

To summarize the roles of AKT-mTOR signaling in the regulation of the DNA damage response and PD-L1 expression in cancer cells, and propose a novel strategy of targeting AKT-mTOR signaling in combination with radioimmunotherapy in the era of cancer immunotherapy

Background

Immunotherapy has greatly improved the clinical outcomes of many cancer patients and has changed the landscape of cancer patient management. However, only a small subgroup of cancer patients (~20–30%) benefit from immune checkpoint blockade-based immunotherapy. The current challenge is to find biomarkers to predict the response of patients to immunotherapy and strategies to sensitize patients to immunotherapy.

Methods

Search and review the literature which were published in PUBMED from 2000–2021 with the key words mTOR, AKT, drug resistance, DNA damage response, immunotherapy, PD-L1, DNA repair, radioimmunotherapy.

Conclusions

More than 50% of cancer patients receive radiotherapy during their course of treatment. Radiotherapy has been shown to reduce the growth of locally irradiated tumors as well as metastatic non-irradiated tumors (abscopal effects) by affecting systemic immunity. Consistently, immunotherapy has been demonstrated to enhance radiotherapy with more than one hundred clinical trials of radiation in combination with immunotherapy (radioimmunotherapy) across cancer types. Nevertheless, current available data have shown limited efficacy of trials testing radioimmunotherapy. AKT-mTOR signaling is a major tumor growth-promoting pathway and is upregulated in most cancers. AKT-mTOR signaling is activated by growth factors as well as genotoxic stresses including radiotherapy. Importantly, recent advances have shown that AKT-mTOR is one of the main signaling pathways that regulate DNA damage repair as well as PD-L1 levels in cancers. These recent advances clearly suggest a novel cancer therapy strategy by targeting AKT-mTOR signaling in combination with radioimmunotherapy.

A narrative review of combination therapy of PD-1/PD-L1 blockade with standard approaches for the treatment of breast cancer: clinical application and immune mechanism

OBJECTIVE

In this review, we aimed to discuss the efficacy of immunotherapy of anti-programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) and potential immune mechanism combination with various standard systemic therapies for breast cancer (BC) such as chemotherapy, targeted therapy, endocrine therapy, and radiotherapy.

BACKGROUND

Single-drug therapy of antibodies against PD-1 and its ligand, PD-L1, have only presented modest responses in patients with BC, partly due to the deficiency of tumor-infiltrating lymphocytes (TILs) and low mutation burden. Thus, the combinations of PD-1/PD-L1 blockade with other approaches which may increase the immune therapy effect are being studied. Moreover, an understanding of the immune mechanism of PD-1/PD-L1 blockade with other approaches will contribute to better application of clinical therapy.

METHODS

We searched the studies that focus on PD-1/PD-L1 therapy with or without other systemic therapy and relative immune mechanisms indicated between 2000 and 2020.

CONCLUSIONS

Anti PD-1/L1 blockade combined with therapeutic approaches is safe and effective in BC, in particular for PD-L1 antibody atezolizumab plus nab-paclitaxel by inducing PD-1/L1 expression and the number of cytotoxic T cells. Otherwise, the toxicity also exists during clinical treatment. Future researches should be evaluated to explore the immune mechanism and vast clinical trials need to be conducted for evidential support for combination therapy of BC.

Nanoplasmonic Sandwich Immunoassay for Tumor-Derived Exosome Detection and Exosomal PD-L1 Profiling

Tumor-derived exosomes play a vital role in the process of cancer development. Quantitative analysis of exosomes and exosome-shuttled proteins would be of immense value in understanding cancer progression and generating reliable predictive biomarkers for cancer diagnosis and treatment. Recent studies have indicated the critical role of exosomal programmed death ligand 1 (PD-L1) in immune checkpoint therapy and its application as a patient stratification biomarker in cancer immunotherapy. Here, we present a nanoplasmonic exosome immunoassay utilizing gold-silver (Au@Ag) core-shell nanobipyramids and gold nanorods, which form sandwich immune complexes with target exosomes. The immunoassay generates a distinct plasmonic signal pattern unique to exosomes with specific exosomal PD-L1 expression, allowing rapid, highly sensitive exosome detection and accurate identification of PD-L1 exosome subtypes in a single assay. The developed nanoplasmonic sandwich immunoassay provides a novel and viable approach for tumor cell-derived exosome detection and analysis with quantitative molecular details of key exosomal proteins, manifesting its great potential as a transformative diagnostic tool for early cancer detection, prognosis, and post-treatment monitoring.

Neoadjuvant treatment of pembrolizumab plus platinum-doublet chemotherapy in stage IIIA squamous cell carcinoma of the lung: a case report

With the popularity of neoadjuvant therapy as first-line treatment, especially for advanced squamous cell carcinoma (SCC), the focus has become accurate individualized treatment. Specifically, toxic side effects of traditional platinum-doublet chemotherapy are high, so treatment with pembrolizumab plus platinum-doublet chemotherapy is safer and more effective. Pembrolizumab is a humanized monoclonal IgG4 kappa anti-PD1 antibody. It is devoid of any cytotoxic activity among the drug effect. Pembrolizumab has been tested clinically in a series of KEYNOTE studies and 12 categories of malignancies have been tested to determine their clinical effects. A 64-year-old man with IIIA SCC of the lung without any surgical contraindications in the preoperative period successfully underwent radical resection and had a great prognosis after neoadjuvant treatment. Chest computed tomography (CT) showed that the left upper lung lesion, hilar and mediastinal lymph nodes were obviously smaller than before, meanwhile, obstructive pneumonia was significantly absorbed. No sign of metastasis was detected by head-abdominopelvic CT and bone scan. Although radiation pneumonitis was an adverse event after postoperative adjuvant therapy, symptoms were relieved with low-dose glucocorticoids. In conclusion, traditional chemotherapy with single agents alone has been gradually replaced by pembrolizumab plus platinum-doublet chemotherapy as a first-line therapy now.

Prognostic impact of PD-1 and PD-L1 expression in malignant pleural mesothelioma: an international multicenter study

BACKGROUND

Programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) immune-checkpoint blockade is a promising new therapeutic strategy in cancer. However, expression patterns and prognostic significance of PD-L1 and PD-1 are still controversial in human malignant pleural mesothelioma (MPM).

METHODS

Formalin-fixed paraffin-embedded (FFPE) tumor samples from 203 MPM patients receiving standard treatment without immunotherapy were collected from 5 European centers. PD-L1 and PD-1 expression of tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs) were measured by immunohistochemistry and correlated with clinical parameters and long-term outcome.

RESULTS

High (>10%) PD-L1 TC and PD-1 TILs expressions were found in 18 (8%) and 39 (24%) patients, respectively. PD-L1 was rarely expressed by TILs [≥1%, n=13 (8%); >10%, n=1]. No significant associations were found between the PD-L1 or PD-1 expression of TCs or TILs and clinicopathological parameters such as stage or histological subtype. Notably, patients with high (>10%) TC-specific PD-L1 expression exhibited significantly worse median overall survival (OS) (6.3 vs. 15.1 months of those with low TC PD-L1 expression; HR: 2.51, P<0.001). In multivariate cox regression analysis adjusted for clinical parameters, high TC PD-L1 expression (>10%) proved to be an independent negative prognostic factor for OS (HR: 2.486, P=0.005). There was no significant correlation between PD-L1 or PD-1 expression of TILs and OS.

CONCLUSIONS

In this multicenter cohort study, we demonstrate that high (>10%) PD-L1 expression of TCs independently predicts worse OS in MPM. Further studies are warranted to investigate the value of PD-L1/PD-1 expression as a marker for treatment response in MPM patients receiving immunotherapy.

Comparison of PD-L1 immunohistochemical assays and the significance of PD-L1 expression in thymoma

Thymoma is a relatively rare malignancy, which is categorized as thymic epithelial tumor but known as the most common pathology that is developed in the anterior mediastinum. Complete resection is recommended for localized tumors and usually favorable prognosis can be obtained. However, poor survival period has been reported in unresectable cases exhibiting extensive invasion or distant metastasis, as effective chemotherapeutic regimens are restrained. We previously assessed expression of programmed death ligand 1 (PD-L1) and programmed death 1 (PD-1) and discussed their prospective application in the immunotherapy of thymic epithelial tumors. After our publication, additional studies using reliable PD-L1 antibodies, which are currently administered to predict efficacy of PD-1/PD-L1 blockade therapy were performed and further characterized PD-L1 in thymoma. Herein, recent knowledge in relation to the significance of PD-L1 expression in thymoma is reviewed based on recent findings using qualified PD-L1 clones. Most studies coherently found high expression of PD-L1 on the cell membrane and cytoplasm of tumor epithelial cells in accordance with previous reports, which is a predictive marker for effectiveness of anti-PD-1/PD-L1 drugs, even when approved PD-L1 antibodies were employed. On the other hand, PD-L1 expression on tumor infiltrating immune cells remains to be sufficiently determined. High PD-L1 expression can be expected in cases with high grade histological subtypes, such as type B2/B3 thymomas, or those with advanced stages III or IV of the disease. Interestingly, the level of PD-L1 expression was found to be upregulated after chemotherapy compared with that before, which could be explained by immunogenic cell death. The prognostic impact of PD-L1 expression in thymoma might be found only when thymic carcinoma patients were excluded. Furthermore, it also could be identified when we analyzed thymomas completely resected, distinct from biopsy and incompletely resected cases.

Augmenting Anticancer Immunity Through Combined Targeting of Angiogenic and PD-1/PD-L1 Pathways: Challenges and Opportunities

Cancer immunotherapy (CIT) with antibodies targeting the programmed cell death 1 protein (PD-1)/programmed cell death 1 ligand 1 (PD-L1) axis have changed the standard of care in multiple cancers. However, durable antitumor responses have been observed in only a minority of patients, indicating the presence of other inhibitory mechanisms that act to restrain anticancer immunity. Therefore, new therapeutic strategies targeted against other immune suppressive mechanisms are needed to enhance anticancer immunity and maximize the clinical benefit of CIT in patients who are resistant to immune checkpoint inhibition. Preclinical and clinical studies have identified abnormalities in the tumor microenvironment (TME) that can negatively impact the efficacy of PD-1/PD-L1 blockade. Angiogenic factors such as vascular endothelial growth factor (VEGF) drive immunosuppression in the TME by inducing vascular abnormalities, suppressing antigen presentation and immune effector cells, or augmenting the immune suppressive activity of regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. In turn, immunosuppressive cells can drive angiogenesis, thereby creating a vicious cycle of suppressed antitumor immunity. VEGF-mediated immune suppression in the TME and its negative impact on the efficacy of CIT provide a therapeutic rationale to combine PD-1/PD-L1 antibodies with anti-VEGF drugs in order to normalize the TME. A multitude of clinical trials have been initiated to evaluate combinations of a PD-1/PD-L1 antibody with an anti-VEGF in a variety of cancers. Recently, the positive results from five Phase III studies in non-small cell lung cancer (adenocarcinoma), renal cell carcinoma, and hepatocellular carcinoma have shown that combinations of PD-1/PD-L1 antibodies and anti-VEGF agents significantly improved clinical outcomes compared with respective standards of care. Such combinations have been approved by health authorities and are now standard treatment options for renal cell carcinoma, non-small cell lung cancer, and hepatocellular carcinoma. A plethora of other randomized studies of similar combinations are currently ongoing. Here, we discuss the principle mechanisms of VEGF-mediated immunosuppression studied in preclinical models or as part of translational clinical studies. We also discuss data from recently reported randomized clinical trials. Finally, we discuss how these concepts and approaches can be further incorporated into clinical practice to improve immunotherapy outcomes for patients with cancer.

A noninterventional, multinational study to assess PD-L1 expression in cytological and histological lung cancer specimens

BACKGROUND

The diagnosis of advanced lung cancer is made with minimally invasive procedures. This often results in the availability of cytological material only for subtype determination and companion diagnostic testing, with the latter being technically and clinically validated on histological material only. Thus, the primary objective of the MO29978 clinical study was to assess programmed death ligand 1 (PD-L1) protein expression on cytology samples as surrogates for histology samples in patients with lung cancer.

METHODS

Formalin-fixed, paraffin-embedded histological samples and cytological cell blocks from 190 patients were analyzed with immunohistochemical assays using the rabbit monoclonal anti-PD-L1 antibody clones SP142 and SP263. PD-L1 expression was quantified on both tumor cells (TC) and tumor-infiltrating immune cells (IC). Overall concordance, sensitivity, specificity, and accuracy, with a 1% cutoff used for both assays, were assessed for PD-L1 expression on TC and IC.

RESULTS

In non-small cell lung cancer histology and cytology samples measured with the PD-L1 (SP142) antibody (n = 173), the intraclass correlation coefficients were 0.40 and 0.06 on TC and IC, respectively. With SP142 and SP263, accuracies of 74.1% for TC and 51.9% for IC and accuracies of 75.2% for TC and 61.2% for IC, respectively, were reported.

CONCLUSIONS

Overall, this study has demonstrated that PD-L1 analysis on TC is feasible in cytological material, but quantification is challenging. Tumor tissue should be preferred over cell block cytology for PD-L1 immunohistochemical analysis unless laboratories have validated their cytology preanalytical approaches and demonstrated the comparability of histology and cytology for TC PD-L1 results.

Higher Tumor Mutation Burden and Higher PD-L1 Activity Predicts the Efficacy of Immune Checkpoint Inhibitor Treatment in a Patient With Four Lung Cancers. A Case Report

We experienced a patient who had four lung cancers with different pathological features, with the most advanced being diagnosed as pStage IIA. A month after the resection, the original lung cancer had metastasized to the lung and to the liver. Of the original lung cancers that were resected, the biggest adenocarcinoma of S3 showed 50 × 31 × 17 mm (invasion 50 mm) and pT2bN0M0 (pStage IIA) with epidermal growth factor receptor (EGFR) mutation (–) and anaplastic lymphoma kinase (ALK) translocation (–), but expression of programmed death ligand 1 (PD-L1) (+) tumor proportion score (TPS) 80%. The pleomorphic carcinoma showed 23 × 20 × 17 mm (invasion 23 mm) and pT1cN0M0 (pStage Ic) with EGFR (–), ALK (–), PD-L1 (+), TPS 95%. Tumor mutation burden (TMB), microsatellite instability (MSI), and structural chromosome aberration analysis by DNA microarray were performed. One hundred somatic mutations in the adenocarcinoma and 75 somatic mutations in the pleomorphic carcinoma were identified, which showed an extremely high mutation rate, although only 16 somatic mutations were common between the two cancers. Chromosomal structural aberrations differed greatly between the two cancers, but common aberrations were found in chromosomes 8 and 10 and partially common aberration in chromosomes 4, 14, 17, and X. These results indicated that each lung cancer originated from a common ancestor clone and developed on an individual molecular evolution. The patient received a single injection of pembrolizumab and 13 injections of atezolizumab. Immune checkpoint inhibitor treatment made metastatic pulmonary and liver lesions reduce in size and show as Partial response (PR). Multiple lung cancers with high PD-L1 activity tend to be TMB-high, reflecting rapid molecular evolution and relevance to the patient's response to immune checkpoint inhibitors. Genomic examination could help determine what had happened in multiple cancers on progression and provide useful data to patient treatment. Each lung cancer originated from a common ancestor clone and developed on an individual molecular evolution.

Selected highlights of the 2019 Pulmonary Pathology Society Biennial Meeting: PD-L1 test harmonization studies

Immune checkpoint inhibitors (ICI) including programmed death 1 (PD-1) inhibitors, such as nivolumab and pembrolizumab, or programmed death ligand 1 (PD-L1) inhibitors, such as atezolizumab and durvalumab, have recently emerged in advanced stage lung cancer as new standards of care. They are now indicated in first- line and second- or later-line treatment of metastatic or locally-advanced stage III non-small cell lung cancer (NSCLC), as well as for metastatic small cell lung cancer (SCLC), as single agent immunotherapy or in combination with chemotherapy. Four PD-L1 immunohistochemistry (IHC) assays have been established and validated in randomized trials, each for a specific ICI. They use different primary monoclonal antibodies, platforms and detection systems, as well as different scoring systems to assess PD-L1 expression either by tumor cells (TCs) and/or by infiltrating immune cells (ICs). Most studies have shown a close analytical performance of three of these clinically-validated standardized assays, but their use restricted to dedicated platforms, which are not all available in most laboratories, questions their applicability. In addition, the relative high costs of the assays have led to the development of in-house protocols in many pathology laboratories. Their use in clinical practice to assess the predictive value of PD-L1 expression for prescription of ICI raises the issue of their reliability and their validation as compared to standardized assays. This article discusses the main comparative studies available between LDT and assays, with clear evidence that LDT can reach a performance equivalent to the trial-validated assays. The requirements are an adequate validation as compared to an appropriate standard, and the participation to external quality assurance programs and training programs for PD-L1 IHC assessment for pathologists.

PD-L1 expression in malignant pleural effusion samples and its correlation with oncogene mutations in non-small cell lung cancer

Background

Programmed death ligand 1 (PD-L1) tumor proportion score (TPS) is currently widely used for selection of immune therapies in non-small cell lung cancer (NSCLC). Most of samples for PD-L1 expression were obtained from tumor tissue. However, the feasible of malignant pleural effusion (MPE) cytological samples for PD-L1 detection is poorly reported. And the correlation between oncogene mutations and PD-L1 expression based on high-throughput sequencing is rarely studied.

Methods

NSCLC MPE cytological samples and partially paired tumor tissue from our institution analyzed for PD-L1 immunohistochemistry (IHC) using the clone SP263 pharmDx kit and evaluated genomic aberrations in all patients using next generation sequencing (NGS).

Results

One hundred and twenty-three MPE cell blocks and 29 paired tumor tissue were successfully tested for PD-L1 expression. PD-L1 TPS of ≥50% were seen in 18.7% (23/123) of all samples. The accordance of PD-L1 expression in tumor tissue and MPE samples was 86.2% (50% as cut-off value). PD-L1 TPS ≥50% tumors were significantly associated with EGFR wild-type (P=0.007), but, no correlation between other genes and PD-L1 expression. A trend of longer overall survival (OS) was observed in patients with PD-L1 TPS <50% than those TPS ≥50% (20.0 vs. 13.8 months, P=0.057). No difference of tumor mutational burden (TMB) was observed between patients with PD-L1 ≥50% and <50% (8.2/MB and 7.7/MB, P=0.47).

Conclusions

Our results suggest that cytological material is feasible for PD-L1 IHC analysis. Gene alterations could partially contribute to select the samples that with different PD-L1 expression. No correlation between the PD-L1 expression and TMB.

Biomarkers for immune checkpoint inhibition in non-small cell lung cancer (NSCLC)

The emergence of immunotherapy has dramatically changed how non-small cell lung cancer is treated, and longer survival is now possible for some patients, even those with advanced disease. Although some patients achieve durable responses to checkpoint blockade, not all experience such benefits, and some suffer from significant immunotoxicities. Given this, biomarkers that predict response to therapy are essential, and testing for tumor programmed death ligand 1(PD-L1) expression is the current standard. The extent of PD-L1 expression determined by immunohistochemistry (IHC) has demonstrated a correlation with treatment response, although limitations with this marker exist. Recently, tumor mutational burden has emerged as an alternative biomarker, and studies have demonstrated its utility, irrespective of the PD-L1 level of a tumor. Gene expression signatures, tumor genotype (such as the presence of an oncogenic driver mutation), as well as the density of tumor-infiltrating lymphocytes in the tumor microenvironment also seem to affect response to immunotherapy and are being researched. Peripheral serum markers are being studied, and some have demonstrated predictive ability, although most are still investigational and need prospective validation. In the current article, the authors review the biomarker PD-L1 as well as other emerging and investigational tissue-based and serum-based markers that have potential to better predict responders to immunotherapy.

Role of the PD-1/PD-L1 Dyad in the Maintenance of Pancreatic Immune Tolerance for Prevention of Type 1 Diabetes

The human pancreas, like almost all organs in the human body, is immunologically tolerated despite the presence of innate and adaptive immune cells that promptly mediate protective immune responses against pathogens in situ. The PD-1/PD-L1 inhibitory pathway seems to play a key role in the maintenance of immune tolerance systemically and within the pancreatic tissue. Tissue resident memory T cells (TRM), T regulatory cells (Treg), macrophages and even β cells exhibit PD-1 or PD-L1 expression that contributes in controlling pancreatic immune homeostasis and tolerance. Dysregulation of the PD-1/PD-L1 axis as shown by animal studies and our recent experience with checkpoint inhibitory blockade in humans can lead to immune dysfunctions leading to chronic inflammatory disease and to type 1 diabetes (T1D) in genetically susceptible individuals. In this review, we discuss the role of the PD-1/PD-L1 axis in pancreatic tissue homeostasis and tolerance, speculate how genetic and environmental factors can regulate the PD-1/PD-L1 pathway, and discuss PD-1/PD-L1-based therapeutic approaches for pancreatic islet transplantation and T1D treatment.

The structural features that distinguish PD-L2 from PD-L1 emerged in placental mammals

Programmed cell death protein 1 (PD-1) is an inhibitory receptor on T lymphocytes that is critical for modulating adaptive immunity. As such, it has been successfully exploited for cancer immunotherapy. Programmed death ligand 1 (PD-L1) and PD-L2 are ligands for PD-1; the former is ubiquitously expressed in inflamed tissues, whereas the latter is restricted to antigen-presenting cells. PD-L2 binds to PD-1 with 3-fold stronger affinity compared with PD-L1. To date, this affinity discrepancy has been attributed to a tryptophan (W110_PD-L2) that is unique to PD-L2 and has been assumed to fit snuggly into a pocket on the PD-1 surface. Contrary to this model, using surface plasmon resonance to monitor real-time binding of recombinantly-expressed and -purified proteins, we found that W110_PD-L2 acts as an "elbow" that helps shorten PD-L2 engagement with PD-1 and therefore lower affinity. Furthermore, we identified a "latch" between the C and D β-strands of the binding face as the source of the PD-L2 affinity advantage. We show that the 3-fold affinity advantage of PD-L2 is the consequence of these two opposing features, the W110_PD-L2 "elbow" and a C-D region "latch." Interestingly, using phylogenetic analysis, we found that these features evolved simultaneously upon the emergence of placental mammals, suggesting that PD-L2-affinity tuning was part of the alterations to the adaptive immune system required for placental gestation.

Programmed death ligand 1 expression in EBUS aspirates of non-small cell lung cancer: Is interpretation affected by type of fixation?

BACKGROUND

Much of the reluctance about using cytology specimens rather than histology specimens to assess programmed death ligand 1 (PD-L1) expression for guiding the use of immune modulating drugs in the management of non-small cell lung cancer (NSCLC) is based on the belief that the alcohol-based fixatives favored by cytopathologists might reduce the antigenicity of PD-L1 and lead to artifactually low expression levels and false-negative reporting. Therefore, this study was performed to determine whether there is any difference in PD-L1 expression between endobronchial ultrasound (EBUS)-guided aspirates of NSCLC fixed in alcohol-based fixatives and those fixed in neutral buffered formalin (NBF), the standard laboratory fixative for histology specimens.

METHODS

The expression of PD-L1 was compared in 50 paired EBUS aspirates of NSCLC taken from the same lymph node during the same procedure. One aspirate of each pair was fixed in an alcohol-based fixative, and the other was fixed in NBF.

RESULTS

In none of the 50 pairs was there any significant difference, qualitative or quantitative, in the strength, pattern, or extent of PD-L1 expression. In the great majority, the expression was identical, regardless of fixation.

CONCLUSIONS

There is no evidence from this study showing that the use of alcohol-based fixatives has any effect on the expression of PD-L1 or its interpretation. Notwithstanding the general challenges in accurately assessing such expression in cytology specimens, pathologists should feel able to interpret them with confidence, and clinicians should feel able to rely on the results.

Biomarker for personalized immunotherapy

Programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) interaction protects cancer cells from immune destruction. Blocking the pathway allows infiltrated T cells to kill tumor cells (TCs), in order to prevent tumor proliferation and distant migration. Immunotherapy with checkpoint blockade (CPB) has emerged as a powerful weapon conquering multiple cancer. However, PD-L1 expression and tumor mutation burden (TMB) are not perfect biomarkers for patients selection to treated with immunotherapy. Increasing evidence showed that other immune-related factored must be payed enough attention and combined biomarkers present promising prospects. Here, we give an overview on available biomarkers in clinic and potential biomarkers for future research.

Immunotherapy a New Hope for Cancer Treatment: A Review

Cancer is a major burden of disease worldwide with considerable impact on society. The tide of immunotherapy has finally changed after decades of disappointing results and has become a clinically validated treatment for many cancers. Immunotherapy takes many forms in cancer treatment, including the adoptive transfer of ex vivo activated T cells, oncolytic viruses, natural killer cells, cancer vaccines and administration of antibodies or recombinant proteins that either costimulate cells or block the so-called immune checkpoint pathways. Recently, cancer immunotherapy has received a high degree of attention, which mainly contains the treatments for programmed death ligand 1 (PD-L1), programmed death 1 (PD-1), chimeric antigen receptors (CARs) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). Here, this paper reviewed the current understandings of the main strategies in cancer immunotherapy (adoptive cellular immunotherapy, immune checkpoint blockade, oncolytic viruses and cancer vaccines) and discuss the progress in the synergistic design of immune-targeting combination therapies.

To treat or not to treat: Patient exclusion in immune oncology clinical trials due to preexisting autoimmune disease

Newly developed immune checkpoint inhibitors (ICIs) demonstrate impressive clinical activity. However, they can also cause life-threatening side effects. The efficacy and toxicity associated with ICIs both derive from unregulated, enhanced immune activation. Health care providers have been hesitant to prescribe these medications to patients who have preexisting autoimmune disease (AD) because of concerns that this may exacerbate their underlying immune condition. These patients have also been excluded from ongoing ICI clinical trials. However, new data suggest that the potential benefits of ICI treatment may outweigh the potential risks for this patient group as long as physicians also provide sufficient monitoring for AD exacerbations or other side effects. Therefore, it may be appropriate to include patients with advanced malignancies and preexisting AD in ICI clinical trials when no other effective cancer treatment options exist. Overall, physicians should avoid excluding patients from ICI therapy unnecessarily when the potential benefits outweigh the potential risks.

Radiotherapy Both Promotes and Inhibits Myeloid-Derived Suppressor Cell Function: Novel Strategies for Preventing the Tumor-Protective Effects of Radiotherapy

Cancer immunotherapies aimed at neutralizing the programmed death-1 (PD-1) immune suppressive pathway have yielded significant therapeutic efficacy in a subset of cancer patients. However, only a subset of patients responds to antibody therapy with either anti-PD-1 or anti-PD-L1 antibodies. These patients appear to have so-called “hot” tumors containing tumor-reactive T cells. Therefore, checkpoint blockade therapy may be effective in a larger percentage of cancer patients if combined with therapeutics that also activate tumor-reactive T cells. Radiotherapy (RT) is a prime candidate for combination therapy because it facilitates activation of both local antitumor immunity and antitumor immunity at non-radiated, distant sites (abscopal response). However, RT also promotes tumor cell expression of PD-L1 and facilitates the development of myeloid-derived suppressor cells (MDSC), a population of immune suppressive cells that also suppress through PD-L1. This article will review how RT induces MDSC, and then describe two novel therapeutics that are designed to simultaneously activate tumor-reactive T cells and neutralize PD-1-mediated immune suppression. One therapeutic, a CD3xPD-L1 bispecific T cell engager (BiTE), activates and targets cytotoxic T and NKT cells to kill PD-L1⁺ tumor cells, despite the presence of MDSC. The BiTE significantly extends the survival time of humanized NSG mice reconstituted with human PBMC and carrying established metastatic human melanoma tumors. The second therapeutic is a soluble form of the costimulatory molecule CD80 (sCD80). In addition to costimulating through CD28, sCD80 inhibits PD-1 suppression by binding to PD-L1 and sterically blocking PD-L1/PD-1 signaling. sCD80 increases tumor-infiltrating T cells and significantly extends survival time of mice carrying established, syngeneic tumors. sCD80 does not suppress T cell function via CTLA-4. These studies suggest that the CD3xPD-L1 BiTE and sCD80 may be efficacious therapeutics either as monotherapies or in combination with other therapies such as radiation therapy for the treatment of cancer.

Intermittent hypoxia enhances the tumor programmed death ligand 1 expression in a mouse model of sleep apnea

Background

As a hallmark of obstructive sleep apnea (OSA), intermittent hypoxia (IH) promotes tumor progress. The high expression of programmed death 1 and programmed death ligand 1 (PD-L1) in tumor leads to immune evasion and subsequently aggravates tumor progress. This study aims to determine the tumor PD-L1 expression under the IH condition.

Methods

A total of 24 C57BL/6J mice were randomly assigned to the normoxia (control, CTL) group and the IH group. Mice in the IH group were subjected to the IH condition for 5 weeks. Lung cancer cells were injected into the flank of each mouse after 1 week of IH exposure. Tumor PD-L1 expression was detected by immunohistochemistry (IHC). Correlation between tumor weight, tumor volume, and expression of PD-L1 was analyzed.

Results

Compared to the CTL group, mice in the IH group had a high PD-L1 expression. The IH can enhance the tumor PD-L1 expression. Tumor weight, volume, and HIF-1α levels were closely associated with the PD-L1 expression in the IH group, while dissimilar findings were observed in the CTL group.

Conclusions

The IH enhances tumor PD-L1 expression in OSA mimicking mice. Additional studies are required to clarify the underlying mechanism.

PD-1/PD-L1 immune checkpoint: Potential target for cancer therapy

Recent studies show that cancer cells are sometimes able to evade the host immunity in the tumor microenvironment. Cancer cells can express high levels of immune inhibitory signaling proteins. One of the most critical checkpoint pathways in this system is a tumor-induced immune suppression (immune checkpoint) mediated by the programmed cell death protein 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1). PD-1 is highly expressed by activated T cells, B cells, dendritic cells, and natural killer cells, whereas PD-L1 is expressed on several types of tumor cells. Many studies have shown that blocking the interaction between PD-1 and PD-L1 enhances the T-cell response and mediates antitumor activity. In this review, we highlight a brief overview of the molecular and biochemical events that are regulated by the PD-1 and PD-L1 interaction in various cancers.

Rational combination of immunotherapy for triple negative breast cancer treatment

Recent evidence indicates that tumor infiltrating lymphocytes (TILs), including cytotoxic T cells, are present in the tumor microenvironment of triple-negative breast cancers (TNBC). Despite the presence of cytotoxic T cells, these tumors still develop, progress, and metastasize, suggesting evasion of immune response. One mechanism of immunosuppression is the presence of the T cell inhibitory molecule, programmed death protein 1 (PD-1), on infiltrating T cells and its cognate ligand programmed death ligand 1 (PD-L1) on tumor cells, myeloid dendritic cells (DCs), and macrophages, in the tumor microenvironment. Because TNBC is immunologically insensitive, combinatorial strategies may be ideal to increase both anti-proliferation activity and cytotoxic T cells activity in TNBC. On the basis of two recently discovered regulatory mechanisms of PD-L1, we discuss the potential interactions to boost anti-tumor immunity against TNBC in this review and propose therapeutic strategies that could reduce PD-L1 expression by chemotherapeutic drugs or targeted therapies and sensitize TNBC to immunotherapies.

Immune profiling of microsatellite instability-high and polymerase ε (POLE)-mutated metastatic colorectal tumors identifies predictors of response to anti-PD-1 therapy

Background

Microsatellite instability-high (MSI-H) and polymerase ε (POLE)-mutated metastatic colorectal cancer (mCRC) represent hypermutated and ultramutated tumor phenotypes, respectively, that may predict benefit to checkpoint blockade [anti-programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1)].

Methods

Immune profiling through multispectral fluorescent immunohistochemistry (IHC) using a multi-marker staining panel was performed on pretreatment tumor specimens from a cohort of MSI-H or POLE-mutated mCRC patients treated with PD-1 blockade at our institution to identify candidate predictors of response to checkpoint inhibitors.

Results

From 4/2013 to 1/2017, a total of 237 mCRC patients with molecularly profiled tumors were screened. Five MSI-H and three POLE-mutated mCRC patients were treated with checkpoint inhibitors. Immune profiling identified higher CD8+ tumor-infiltrating lymphocytes (TILs) within the tumor microenvironment (TME) of responders (CR or PR as best response) than nonresponders (SD or PD as best response). Responders had significantly higher densities of CD8+ PD-1+ TILs than nonresponders (P=0.0007). PD-L1 expression (P=0.73), CD4+ T-cell density (P=0.39), and CD4+ FOXP3+ T-cell density (P=0.68) did not significantly differ, but the percentage of CD4+ Tbet+ T-cells (Th1 phenotype) was also significantly higher in responders than nonresponders (P=0.0007).

Conclusions

Higher densities of CD8+ TILs, PD-1-expressing CD8+ TILs, and tumor-infiltrating immune cells with a Th1 phenotype in the TME may predict response to checkpoint inhibitors in MSI-H and POLE-mutated mCRC.

Thymic tumors and immune checkpoint inhibitors

Thymoma and thymic carcinoma, known as the most common features of thymic epithelial tumors (TETs), are thoracic malignancies displaying varied clinical features and prognosis. These neoplasms being frequently ineligible for surgical complete resection as a curative treatment because of extensive tumor spread, effectual nonsurgical treatments are needed; however, an optimal chemotherapeutic regimen has not been identified, although some regimens have been shown to be active. Immunotherapy is effective for other malignancies and may be promising as a therapeutic alternative for refractory TETs. Thus far, several studies have determined the expression of programmed death ligand 1 (PD-L1) and programmed death 1 (PD-1) in TETs, including its clinicopathological and prognostic significance. The results have been conflicting due to the different immunohistochemical antibodies employed and distinct cutoff values. However, many authors identified abundant PD-L1 expression in TETs, which is considered as an important predictive factor for therapeutic effect of PD-1 inhibitors in other malignant tumors. In some clinical trials, an acceptable clinical efficacy of PD-1 inhibitor for TETs has been reported as expected; however, concerns regarding immunological adverse events have been raised. To optimize these therapeutic agents for refractory TETs, additional studies which evaluate clinical availabilities of immunotherapeutic drugs and characterize their basic mechanisms of action against immunotherapeutic targets are both urgently required.

Four immunohistochemical assays to measure the PD-L1 expression in malignant pleural mesothelioma

Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 pathway are expected to be a novel therapy for combating future increases in numbers of malignant pleural mesothelioma (MPM) patients. However, the PD-L1 expression, which is a predictor of the response to ICIs, is unclear in MPM. We studied the PD-L1 expression using four immunohistochemical assays (SP142, SP263, 28-8 and 22C3) in 32 MPM patients. The PD-L1 expression in tumor cells and immune cells was evaluated to clarify the rate of PD-L1 expression and the concordance among the four assays in MPM. The positivity rate of PD-L1 expression was 53.1% for SP142, 28.1% for SP263, 53.1% for 28-8, and 56.3% for 22C3. Nine cases were positive and 10 were negative for all assays. Discordance among the four assays was found in 13 cases. The concordance rates between SP142 and 22C3 and between 28-8 and 22C3 were the highest (84.4%). The concordance rates between SP263 and the other three assays were low (71.9% to 75.0%). The PD-L1 expression in MPM was almost equivalent for three of the assays. Given the cut-off values set in our study, these findings suggested that these assays, except for SP263, can be used for accurate PD-L1 immunostaining in MPM.

Programmed death ligand 1 testing in non-small cell lung carcinoma cytology cell block and aspirate smear preparations

BACKGROUND

Immune checkpoint inhibitors targeting the programmed cell death 1 (PD-1) receptor and its ligand, programmed death ligand 1 (PD-L1), have emerged as a therapeutic approach for patients with non-small cell lung carcinoma (NSCLC). PD-L1 expression, assessed by immunohistochemistry (IHC), is used to select patients for PD-1/PD-L1 inhibitor therapy. Most studies have been performed with histology specimens, with limited data available on the performance in cytology specimens. This study evaluated PD-L1 in cytology specimens and compared the results with those from paired core-needle biopsy for concordance.

METHODS

Forty-one NSCLC fine-needle aspiration cases that had paired core-needle biopsy specimens with PD-L1 IHC were selected. A Papanicolaou-stained direct smear and a cell block section from each case were stained with a Dako PD-L1 pharmDx antibody (clone 22C3). Only slides with 100 or more tumor cells (37 smears and 38 cell blocks) were evaluated. Tumor proportion scores (TPS) were assessed on the basis of the partial/complete membranous staining of tumor cells and were correlated with those of paired core-needle biopsy.

RESULTS

All 9 smears that were negative for PD-L1 staining showed 100% concordance with the paired core-needle biopsy, whereas 28 smears with PD-L1 expression showed a similar TPS, except for 1 smear that was discordant. In contrast, 10 negative paired core-needle biopsy cases corresponded to 9 concordant negative cell blocks, whereas 1 cell block had a TPS of 1% to 5%. The remaining 28 cell blocks demonstrated PD-L1 expression, with 22 cases showing a TPS similar to that of the paired core-needle biopsy, whereas 6 cell blocks were discordant, likely because of intratumoral heterogeneity.

CONCLUSIONS

The results show that NSCLC cytology samples evaluated for PD-L1 have high concordance with paired core-needle biopsy samples and can be used for assessing PD-L1 expression. Cancer Cytopathol 2018;126:342-52. © 2018 American Cancer Society.

HLA class I loss and PD-L1 expression in lung cancer: impact on T-cell infiltration and immune escape

Immune-checkpoint inhibitors show encouraging results in cancer treatment, but the clinical benefit is limited exclusively to a subset of patients. We analyzed the density and composition of tumor T-cell infiltration in non-small-cell lung carcinoma (NSCLC) in relation to PD-L1 and HLA class I (HLA-I) expression. We found that positive HLA-I expression, independently on PD-L1 status, is the key factor determining the increased density of the immune infiltrate. When both markers were analyzed simultaneously, we identified four phenotypes of HLA-I and PD-L1 co-expression. They demonstrated different patterns of tumor infiltration and clinicopathologic characteristics, including the tumor size and lymphatic spread. All HLA-I+/PD-L1+ tumors had a high degree of intratumoral infiltration with CD8+T-lymphocytes, whereas HLA-I loss was associated with a significantly reduced number of tumor infiltrating T-lymphocytes mostly restrained in the stroma surrounding the tumor nest. HLA-I-negative/PD-L1-positive tumors had bigger size (T) and lower grade of infiltration with CD8+T-cells. It represents a cancer immune escape phenotype that combines two independent mechanisms of immune evasion: loss of HLA-I and upregulation of PD-L1. Using GCH-array analysis of human lung cancer cell lines we found that the loss of heterozygosity (LOH) with complete or partial deletion of HLA-I genes is the principal mechanism of HLA-I alterations. This irreversible defect, which could potentially decrease the clinical efficacy of lung cancer immunotherapy, appears to be underestimated. In conclusion, our results suggest that the analysis of HLA-I is very important for the selection of potential responders to cancer immunotherapy.

A comparative study of PD-L1 immunohistochemical assays with four reliable antibodies in thymic carcinoma

Currently, four immunohistochemical assays are registered with the US Food and Drug Administration to detect the expression of PD-L1. We investigated the PD-L1 expression in thymic carcinomas using these four diagnostic assays. The cases of 53 patients were reviewed and their specimens were subjected to four PD-L1 assays with different antibodies (SP142, SP263, 22C3, and 28-8). The PD-L1 expression in tumor cells (TCs) and immune cells (ICs) was evaluated. In TCs, the four assays showed similar scores in each case. Histopathologically, high TC scores were observed in squamous cell carcinomas (SqCCs). Meanwhile, there were no significant relationships among the IC scores in the four assays. In SqCCs, the high expression of PD-L1 (defined as ≥50% TC score) in TCs tended to be associated with early stage cancer. The patients with high expression levels of PD-L1 tended to show longer overall survival in the 22C3 assays (p=0.0200). In thymic carcinomas, the staining pattern showed high concordance among the four assays when TCs – rather than ICs – were stained. High PD-L1 positivity in TCs, especially in SqCCs, indicated that PD-1/PD-L1 targeted therapy may be a promising therapeutic approach.

Crizotinib plus radiotherapy in brain oligoprogressive NSCLC ROS1 rearranged and PD-L1 strong

ROS1+ patients represent a unique molecular subset of non-small cell lung cancer (NSCLC). Early phase clinical trials have shown a high response rate to crizotinib in these patients. We describe a case of an 18 years old woman, never smoker, with NSCLC ROS1+ and miliary brain metastases treated with crizotinib and radiotherapy. From October 2014 to June 2015 the Patient was treated with crizotinib. The first intracranial time to progression (IT-TTP) occurred after 7 months; the patient underwent stereotactic radiosurgery (SRS) and continued TKI treatment. The second IT-TTP appeared after 16 months. A continued response in the chest was observed for all the 23 months of crizotinib treatment. At the progression, we assessed programmed death ligand 1 (PD-L1) expression by immunohistochemistry, that resulted highly expressed. Our report indicates that the integration of crizotinib with local treatments should be considered in ROS1 NSCLC patients experiencing oligometastatic progression. Moreover, this case is an example of PD-L1 strong in oncogene addicted patients.

Poly(I:C) primes primary human glioblastoma cells for an immune response invigorated by PD-L1 blockade

Prognosis of glioblastoma remains dismal, underscoring the need for novel therapies. Immunotherapy is generating promising results, but requires combination strategies to unlock its full potential. We investigated the immunomodulatory capacities of poly(I:C) on primary human glioblastoma cells and its combinatorial potential with programmed death ligand (PD-L) blockade. In our experiments, poly(I:C) stimulated expression of both PD-L1 and PD-L2 on glioblastoma cells, and a pro-inflammatory secretome, including type I interferons (IFN) and chemokines CXCL9, CXCL10, CCL4 and CCL5. IFN-β was partially responsible for the elevated PD-1 ligand expression on these cells. Moreover, real-time PCR and chloroquine-mediated blocking experiments indicated that poly(I:C) triggered Toll-like receptor 3 to elicit its effect. Cocultures of poly(I:C)-treated glioblastoma cells with peripheral blood mononuclear cells enhanced lymphocytic activation (CD69, IFN-γ) and cytotoxic capacity (CD107a, granzyme B). Additional PD-L1 blockade further propagated immune activation. Besides activating immunity, poly(I:C)-treated glioblastoma cells also doubled the attraction of CD8⁺ T cells, and to a lesser extent CD4⁺ T cells, via a mechanism which included CXCR3 and CCR5 ligands. Our results indicate that by triggering glioblastoma cells, poly(I:C) primes the tumor microenvironment for an immune response. Secreted cytokines allow for immune activation while chemokines attract CD8⁺ T cells to the front, which are postulated as a prerequisite for effective PD-1/PD-L1 blockade. Accordingly, additional blockade of the concurrently elevated tumoral PD-L1 further reinforces the immune activation. In conclusion, our data proposes poly(I:C) treatment combined with PD-L1 blockade to invigorate the immune checkpoint inhibition response in glioblastoma.

Results of clinical trials with anti-programmed death 1/programmed death ligand 1 inhibitors in lung cancer

One of the main hallmarks of cancer is the capability of evading immune destruction. In order to drive tumor progression, malignant cells are able to promote immunosuppressive mechanisms avoiding recognition and elimination. Increasing knowledge of the mechanisms of immune tolerance has led to the identification of several membrane receptors strongly implicated in this cancer feature: the immune checkpoints. Among them, programmed death 1 (PD-1) receptors and their ligands have been identified as potential targets for a new anti-cancer therapeutic approach: the use of immune-modulatory monoclonal antibodies designed to interrupt the immune escape activated by the interaction of PD-1 receptors and their ligands. Five of these antibodies are now in their late stages of clinical development and this review will summarize their up-to-date efficacy and toxicity data.

Immunotherapy for advanced gastric and esophageal cancer: preclinical rationale and ongoing clinical investigations

Gastric and esophageal cancers represent a major global cancer burden and novel approaches are needed. Despite recent improvements in outcomes with trastuzumab and ramucirumab the prognosis for advanced disease remains poor, with a median overall survival of 1 year. Comprehensive genomic characterization has defined molecular subgroups and potentially actionable genomic alterations, but the majority of patients do not yet benefit from molecularly directed therapies. Breakthroughs in immune checkpoint blockade have provided new therapeutic avenues in melanoma, and continue to expand into other tumor types, with ongoing investigations in gastrointestinal (GI) malignancies. The frequency of programmed death ligand 1 (PD-L1) overexpression, a putative response biomarker, approaches forty percent in gastric cancers. Translational studies and molecular classification suggest gastric and esophageal cancers are candidate malignancies for immune checkpoint inhibition trials and early clinical data is promising. Here we review the mechanisms, preclinical, and early clinical data supporting the role for immune checkpoint blockade in gastric and esophageal cancer.