Markedly decreased expression of class I histocompatibility antigens, protein, and mRNA in human small-cell lung cancer

PD-L1 as a biomarker of response to immune-checkpoint inhibitors

Immune-checkpoint inhibitors targeting PD-1 or PD-L1 have already substantially improved the outcomes of patients with many types of cancer, although only 20-40% of patients derive benefit from these new therapies. PD-L1, quantified using immunohistochemistry assays, is currently the most widely validated, used and accepted biomarker to guide the selection of patients to receive anti-PD-1 or anti-PD-L1 antibodies. However, many challenges remain in the clinical use of these assays, including the necessity of using different companion diagnostic assays for specific agents, high levels of inter-assay variability in terms of both performance and cut-off points, and a lack of prospective comparisons of how PD-L1⁺ disease diagnosed using each assay relates to clinical outcomes. In this Review, we describe the current role of PD-L1 immunohistochemistry assays used to inform the selection of patients to receive anti-PD-1 or anti-PD-L1 antibodies, we discuss the various technical and clinical challenges associated with these assays, including regulatory issues, and we provide some perspective on how to optimize PD-L1 as a selection biomarker for the future treatment of patients with solid tumours.

The landscape of immune checkpoints expression in non-small cell lung cancer: a narrative review

With the increasing clinical potential of tumor immunotherapy, more and more clinical trials are undergoing with immune checkpoint inhibitors (ICIs). Immune checkpoints (ICs) have been identified as crucial regulators of the immune response and have improved ICIs-inhibitor therapeutic strategies. The most important ICs in lung cancer include programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), lymphocyte activation gene-3 (LAG-3), major histocompatibility complex class II (MHC II), T cell immunoglobulin and mucin-domain containing-3 (TIM-3), and Galectin-9 (GAL-9), OX-40, OX40L. However, the expression and prognostic value of these ICs are still controversial. Among them, high expression of PD-L1 on tumor cells (>50%) predicts a better therapeutic effect of anti-PD-1 monoclonal antibody compared to patients with low PD-L1 expression. However, only 20–30% of non-small cell lung cancer (NSCLC) patients seem to get benefit from immunotherapy. In order to improve the immunotherapy outcomes, more and more attention is paid to combination immunotherapy. Analyzing the co-expression of ICs can give us a more comprehensive basis for combination immunotherapy. This review article summarized our comprehensive expression of ICs based on our previous research, and analyzed their correlation with prognosis in NSCLC patients. We also provided suggestions for potentially personalized combination immunotherapy in NSCLC.

Front Line Applications and Future Directions of Immunotherapy in Small-Cell Lung Cancer

After being stagnant for decades, there has finally been a paradigm shift in the treatment of small-cell lung cancer (SCLC) with the emergence and application of immune checkpoint inhibitors (ICIs). Multiple trials of first-line ICI-chemotherapy combinations have demonstrated survival benefit compared to chemotherapy alone in patients with extensive-stage SCLC, establishing this as the new standard of care. ICIs are now being applied in the potentially curative limited-stage setting, actively being investigated as concurrent treatment with chemoradiation and as adjuvant treatment following completion of chemoradiation. This review highlights the evidence behind the practice-changing addition of ICIs in the first-line setting of extensive-stage SCLC, the potentially practice-changing immunotherapy trials that are currently underway in the limited-stage setting, and alternate immunotherapeutic strategies being studied in the treatment of SCLC.

Small-cell lung cancer

Small-cell lung cancer (SCLC) represents about 15% of all lung cancers and is marked by an exceptionally high proliferative rate, strong predilection for early metastasis and poor prognosis. SCLC is strongly associated with exposure to tobacco carcinogens. Most patients have metastatic disease at diagnosis, with only one-third having earlier-stage disease that is amenable to potentially curative multimodality therapy. Genomic profiling of SCLC reveals extensive chromosomal rearrangements and a high mutation burden, almost always including functional inactivation of the tumour suppressor genes TP53 and RB1. Analyses of both human SCLC and murine models have defined subtypes of disease based on the relative expression of dominant transcriptional regulators and have also revealed substantial intratumoural heterogeneity. Aspects of this heterogeneity have been implicated in tumour evolution, metastasis and acquired therapeutic resistance. Although clinical progress in SCLC treatment has been notoriously slow, a better understanding of the biology of disease has uncovered novel vulnerabilities that might be amenable to targeted therapeutic approaches. The recent introduction of immune checkpoint blockade into the treatment of patients with SCLC is offering new hope, with a small subset of patients deriving prolonged benefit. Strategies to direct targeted therapies to those patients who are most likely to respond and to extend the durable benefit of effective antitumour immunity to a greater fraction of patients are urgently needed and are now being actively explored.

Combination therapy: Future directions of immunotherapy in small cell lung cancer

Small cell lung cancer (SCLC), an aggressive and devastating malignancy, is characterized by rapid growth and early metastasis. Although most patients respond to first-line chemotherapy, the majority of patients rapidly relapse and have a relatively poor prognosis. Fortunately, immunotherapy, mainly including antibodies that target the cytotoxic T lymphocyte antigen-4 (CTLA-4), checkpoints programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1) to block immune regulatory checkpoints on tumor cells, immune cells, fibroblasts cells and endothelial cells, has achieved the milestone in several solid tumors, such as melanoma and non-small-cell lung carcinomas (NSCLC). In recent years, immunotherapy has made progress in the treatment of patients with SCLC, while its response rate is relatively low to monotherapy. Interestingly, the combination of immunotherapy with other therapy, such as chemotherapy, radiotherapy, and targeted therapy, preliminarily achieve greater therapeutic effects for treating SCLC. Combining different immunotherapy drugs may act synergistically because of the complementary effects of the two immune checkpoint pathways (CTLA-4 and PD-1/PD-L1 pathways). The incorporation of chemoradiotherapy in immunotherapy may augment antitumor immune responses because chemoradiotherapy can enhance tumor cell immunogenicity by rapidly inducing tumor lysis and releasing tumor antigens. In addition, since immunotherapy drugs and the molecular targets drugs act on different targets and cells, the combination of these drugs may achieve greater therapeutic effects in the treatment of SCLC. In this review, we focused on the completed and ongoing trials of the combination therapy for immunotherapy of SCLC to find out the rational combination strategies which may improve the outcomes for SCLC.

Harnessing the Immune System to Tackle Small Cell Lung Cancer

Immunotherapy has improved first-line therapy for small cell lung cancer and has activity in the relapsed setting as well. The immunobiology of small cell lung cancer poses challenges for immunotherapy, and efforts are underway to unlock to the potential of immunotherapy through the identification of meaningful disease subsets and the development of novel combination therapies.

In Search of the Long-Desired 'Copernican Therapeutic Revolution' in Small-Cell Lung Cancer

Small-cell lung cancer has defied our scientific community for decades. Chemotherapy has been the mainstay treatment for small-cell lung cancer (SCLC) and unlike its counterpart, non-small cell lung cancer, no significant therapeutic breakthroughs have been made since the 1970s. Among the reasons for this slow-paced therapeutic development, one that stands out is the distinctive and almost universal loss of function of the tumour suppressor genes TP53 and RB1 in this disease, for which pharmacological activation has yet to be achieved, despite having been highly sought after. Although no molecularly targeted approach has been approved for clinical practice thus far, several strategies are currently exploring the potential to drug the tumour's "Achilles heel" that stems from essential pathways regulating DNA-damage response. Most recently, we have witnessed newfound reasons to hope, as the combination of immunotherapy and systemic chemotherapy has improved survival outcomes, representing the first landmark achievement in decades and a new standard of care for patients with extensive disease SCLC. However, continuous efforts are still needed towards a better understanding of the molecular pathways that singularise this tumour to eventually identify the predictive biomarkers that might result in the development of a more rational therapeutic approach, including the use of immunotherapy combinations. In this review we aim to uncover critical aspects of the immune microenvironment and biology of SCLC and provide an overview of the current and future landscape of promising therapeutic opportunities. The challenge still stands, but regardless, we are living in exciting times to finally check SCLC off the "bucket list" of our scientific community.

Emerging drugs for small cell lung cancer: a focused review on immune checkpoint inhibitors

INTRODUCTION

Small cell lung cancer (SCLC) is an aggressive malignancy that accounts for 15% of all lung cancers. It is characterized by initial responsiveness to therapy followed by rapid disease progression that is relatively resistant to further treatment. Recently, the addition of an immune checkpoint inhibitor (ICI) to chemotherapy has improved survival in patients with advanced disease, the first advance in systemic therapy in SCLC in over 30 years.

AREAS COVERED

In this review, we present an overview of SCLC with a focus on the scope of the problem and standard treatment, followed by a critical assessment of scientific rationale for immunotherapy in SCLC and the clinical trials that have been performed with ICIs in SCLC. Finally, we address ongoing hurdles for the development of ICIs in SCLC and potential avenues for further study.

EXPERT OPINION

Despite solid biological rationale, the results of clinical trials of ICIs in SCLC have yielded modest benefits. A small subset of patients does achieve long-term benefit, but further development of ICIs in SCLC will depend on the identification of predictive biomarkers and the design of combination regimens that take advantage of the molecular alterations that drive the immune-avoidance mechanisms and survival of SCLC cells.

New Approaches to SCLC Therapy: From the Laboratory to the Clinic

The outcomes of patients with SCLC have not yet been substantially impacted by the revolution in precision oncology, primarily owing to a paucity of genetic alterations in actionable driver oncogenes. Nevertheless, systemic therapies that include immunotherapy are beginning to show promise in the clinic. Although, these results are encouraging, many patients do not respond to, or rapidly recur after, current regimens, necessitating alternative or complementary therapeutic strategies. In this review, we discuss ongoing investigations into the pathobiology of this recalcitrant cancer and the therapeutic vulnerabilities that are exposed by the disease state. Included within this discussion, is a snapshot of the current biomarker and clinical trial landscapes for SCLC. Finally, we identify key knowledge gaps that should be addressed to advance the field in pursuit of reduced SCLC mortality. This review largely summarizes work presented at the Third Biennial International Association for the Study of Lung Cancer SCLC Meeting.

Potential immune escape mechanisms underlying the distinct clinical outcome of immune checkpoint blockades in small cell lung cancer

Small cell lung cancer (SCLC) is one of the deadliest cancer types in the world. Despite the high response rate to frontline platinum-containing doublets, relapse is inevitable for the majority of patients and the prognosis is poor. Topotecan, which has limited efficacy, has remained the standard second-line therapy for approximately three decades. Although SCLC has a high mutation burden, the clinical efficacy of immune checkpoint blockades (ICBs) in SCLC is far less pronounced than that in non-small cell lung cancer (NSCLC). Only atezolizumab in combination with chemotherapy improved overall survival over chemotherapy alone in the phase III CheckMate 133 trial and has recently received FDA approval as first-line therapy. Most studies concerning ICBs in SCLC are limited to early-phase studies and found that ICBs were not superior to traditional chemotherapy. Why is there such a large difference between SCLC and NSCLC? In this review, comparative analyses of previous studies indicate that SCLC is even more immunodeficient than NSCLC and the potential immune escape mechanisms in SCLC may involve the low expression of PD-L1 and the downregulation of major histocompability complex (MHC) molecules and regulatory chemokines. In consideration of these immune dysfunctions, we speculate that chemotherapy and radiotherapy prior to immunotherapy, the combination of ICBs with antiangiogenic treatment, and selecting tumor mutation burden in combination with PD-L1 expression as biomarkers could be promising strategies to improve the clinical efficacy of immunotherapy for SCLC.

Durvalumab in Combination with Olaparib in Patients with Relapsed SCLC: Results from a Phase II Study

PURPOSE

Despite high tumor mutationburden, immune checkpoint blockade has limited efficacy in SCLC. We hypothesized that poly (ADP-ribose) polymerase inhibition could render SCLC more susceptible to immune checkpoint blockade.

METHODS

A single-arm, phase II trial (NCT02484404) enrolled patients with relapsed SCLC who received durvalumab, 1500 mg every 4 weeks, and olaparib, 300 mg twice a day. The primary outcome was objective response rate. Correlative studies included mandatory collection of pretreatment and during-treatment biopsy specimens, which were assessed to define SCLC immunephenotypes: desert (CD8-positive T-cell prevalence low), excluded (CD8-positive T cells in stroma immediately adjacent/within tumor), and inflamed (CD8-positive T cells in direct contact with tumor).

RESULTS

A total of 20 patients were enrolled. Their median age was 64 years, and most patients (60%) had platinum-resistant/refractory disease. Of 19 evaluable patients, two were observed to have partial or complete responses (10.5%), including a patient with EGFR-transformed SCLC. Clinical benefit was observed in four patients (21.1% [95% confidence interval: 6.1%-45.6%]) with confirmed responses or prolonged stable disease (≥8 months). The most common treatment-related adverse events were anemia (80%), lymphopenia (60%), and leukopenia (50%). Nine of 14 tumors (64%) exhibited an excluded phenotype; 21% and 14% of tumors exhibited the inflamed and desert phenotypes, respectively. Tumor responses were observed in all instances in which pretreatment tumors showed an inflamed phenotype. Of the five tumors without an inflamed phenotype at baseline, no during-treatment increase in T-cell infiltration or programmed death ligand 1 expression on tumor-infiltrating immune cells was observed.

CONCLUSIONS

The study combination did not meet the preset bar for efficacy. Pretreatment and during-treatment biopsy specimens suggested that tumor immune phenotypes may be relevant for SCLC responses to immune checkpoint blockade combinations. The predictive value of preexisting CD8-positive T-cell infiltrates observed in this study needs to be confirmed in larger cohorts.

Oncolytic virotherapy for small-cell lung cancer induces immune infiltration and prolongs survival

Oncolytic virotherapy has been proposed as an ablative and immunostimulatory treatment strategy for solid tumors that are resistant to immunotherapy alone; however, there is a need to optimize host immune activation using preclinical immunocompetent models in previously untested common adult tumors. We studied a modified oncolytic myxoma virus (MYXV) that shows high efficiency for tumor-specific cytotoxicity in small-cell lung cancer (SCLC), a neuroendocrine carcinoma with high mortality and modest response rates to immune checkpoint inhibitors. Using an immunocompetent SCLC mouse model, we demonstrated the safety of intrapulmonary MYXV delivery with efficient tumor-specific viral replication and cytotoxicity associated with induction of immune cell infiltration. We observed increased SCLC survival following intrapulmonary MYXV that was enhanced by combined low-dose cisplatin. We also tested intratumoral MYXV delivery and observed immune cell infiltration associated with tumor necrosis and growth inhibition in syngeneic murine allograft tumors. Freshly collected primary human SCLC tumor cells were permissive to MYXV and intratumoral delivery into patient-derived xenografts resulted in extensive tumor necrosis. We confirmed MYXV cytotoxicity in classic and variant SCLC subtypes as well as cisplatin-resistant cells. Data from 26 SCLC human patients showed negligible immune cell infiltration, supporting testing MYXV as an ablative and immune-enhancing therapy.

Immunotherapy for small cell lung cancer: mechanisms of resistance

INTRODUCTION

Small cell lung cancer (SCLC) is a highly malignant disease with a dismal prognosis that is currently being tested for theclinical activity of checkpoint inhibitors. SCLC is associated with smoking and exhibits a high mutational burden. However, low expression of PD-L1 and MHC antigens, as well low levels of immune cell infiltration and rapid tumor progress seems to limit the efficacy of anticancer immunity. Nevertheless, long-term survival was reported from studies using anti-PD-1/PD-L1 and CTLA-4 agents.

AREAS COVERED

Data of clinical trials of checkpoint inhibitors in SCLC show lower success rates compared to NSCLC. The mechanisms of resistance to immunotherapy are discussed for their relevance to SCLC patients.

EXPERT OPINION

Although some factors, such as a high mutation rate, favor immunotherapy for SCLC patients, downregulation of MHC class I, low expression of PD-L1, poor tumor infiltration by effector T cells, presence of myeloid-derived suppressor cells as well as regulatory T lymphocytes counteract the immune system activation by checkpoint inhibitors. Furthermore, this tumor develops avascular regions which have immunosuppressive effects and restrict access of lymphocytes and antibodies. In conclusion, immunotherapy in SCLC is effective in highly selected patients with good performance status and special and unknown preconditions contributing to long-lasting responses.

[Clinical Development of Immunotherapy for Small Cell Lung Cancer]

小细胞肺癌（small cell lung cancer, SCLC）约占肺癌的15%，恶性程度高，侵袭性强，尽管其对放化疗比较敏感，但极易发生耐药，复发率高，后期治疗效果欠佳。近年来，免疫抑制剂展现了良好的抗肿瘤活性，特别是程序性死亡受体-1/配体-L1（programmed death receptor-1/ligand-L1, PD-1/L1）和细胞毒性T淋巴细胞相关抗原-4（cytotoxic T-lymphocyte-associated antigen 4, CTLA-4）检查点抑制剂的问世改变了肿瘤治疗的格局，同时SCLC具有高免疫源性，高突变负荷等免疫利好因素，免疫检查点抑制剂有望成为该领域治疗的重要突破口，本文将对SCLC免疫治疗的临床研究进展做简要综述。

Gains and Losses of HLA Class II (DR) and CD4 in Atypical Hyperplasia, Carcinoma in situ and Infiltrating Ductal Carcinoma of the Breast

Aim: Breast cancer is a frequent cause of death among women with gynaecologic malignancies despite the introduction of combination chemotherapy. There is therefore a need for new therapeutic strategies for patients with breast cancer, such as cellular immunotherapy. In this immunohistochemical study we analyzed the epithelial expression of major histocompatibility complex (MHC) class II (HLA-DR) on atypical and malignant primary mammary epithelial cells, as well as the magnitude of the stromal T lymphocytes (T4 subset) at the tumor site. Experimental design: The study was carried out retrospectively in tumor tissue from 82 patients with mammary lesions (31 cases of atypical ductal hyperplasia -ADH-, 12 cases of ductal carcinoma in situ –DCIS- and 39 cases of infiltrating ductal carcinoma not otherwise specified -IDC-NOS). Medullary carcinomas were not included in our investigation. Material used had been formalin fixed and paraffin embedded. Results: HLA class II (DR) was expressed in 20 of 31 ADHs (64.5%), in 4 of 12 DCISs (33.3%), and in 10 of 39 IDC-NOSs (25.6%). CD4 was expressed in 9 of 31 ADHs (29%), in 5 of 12 DCISs (42%), and in 26 of 39 IDCNOSs (67%). Conclusions: The results showed decreased epithelial expression of HLA class II (DR) and increased stromal expression of CD4, as the lesion progressed to malignancy. Gradual loss of epithelial HLA class II expression might be a manifestation of cellular differentiation from the atypical form versus the malignant one, signaling simultaneously a selective effect on the response capacity of the immune system.

Immune checkpoint inhibitors and small cell lung cancer: what's new?

Despite extensive research no meaningful progress in systemic treatment of small cell lung cancer (SCLC) has been made in the past decades. Earlier attempts with immunotherapy including interferon and vaccination approaches had limited success. High mutational load, smoking history and potentially also the frequent presence of paraneoplastic phenomena-indicating an activated immune system-represent a rationale for a benefit from immune checkpoint inhibitors in SCLC. However, the likelihood of response is diminished due to poor T-cell activation resulting from low expression of MHC class I antigens, low amounts of tumor infiltrating lymphocytes (TILs) and low PD-L1 expression rates. Recently, early reports from studies with checkpoint inhibitors have shown promising results with the potential for long term disease control in a subset of SCLC patients. However, reliable predictive biomarkers to better define the population drawing most benefit are currently lacking. Results from ongoing phase III trials in different treatment lines and in the maintenance setting are eagerly awaited.

In Vivo and in Vitro Growth of SCLC Cells Derived from Biopsies

In order to increase the availability of SCLC cells derived from biopsies, in vivo and in vitro growth methods were investigated. The cells grown in both conditions were periodically monitored for reactivity with 2 monoclonal antibodies (MAbs): MLuC1 directed against SCLC cells and IM1 which recognizes the class II antigen on activated lymphocytes and macrophages. About 50 % of the 28 analyzed SCLC specimens were found to proliferate in one or both systems. The in vitro-grown cells exhibited the same heterogeneity found in the original cell suspensions and moreover, in some cases only normal cells were recovered after several in vitro passages. From the subcutaneous transplanted tumors a large number of MLuC1-positive tumor cells could easily be recovered, thus indicating the validity of the in vivo methodology. The MBr1 MAb, directed against an epithelial antigen, was found to react with about 50 % of the 26 tested tumors, mainly those which demonstrated in vivo and/or in vitro growth capacity. These data suggest that only some tumors, presumably with peculiar biological characteristics, can efficiently grow in these artificial systems.

Antitumor activity of CD56-chimeric antigen receptor T cells in neuroblastoma and SCLC models

The CD56 antigen (NCAM-1) is highly expressed on several malignancies with neuronal or neuroendocrine differentiation, including small-cell lung cancer and neuroblastoma, tumor types for which new therapeutic options are needed. We hypothesized that CD56-specific chimeric antigen receptor (CAR) T cells could target and eliminate CD56-positive malignancies. Sleeping Beauty transposon-generated CD56R-CAR T cells exhibited αβT-cell receptors, released antitumor cytokines upon co-culture with CD56⁺ tumor targets, demonstrated a lack of fratricide, and expression of cytolytic function in the presence of CD56⁺ stimulation. The CD56R-CAR⁺ T cells are capable of killing CD56⁺ neuroblastoma, glioma, and SCLC tumor cells in in vitro co-cultures and when tested against CD56⁺ human xenograft neuroblastoma models and SCLC models, CD56R-CAR⁺ T cells were able to inhibit tumor growth in vivo. These results indicate that CD56-CARs merit further investigation as a potential treatment for CD56⁺ malignancies.

IL-27 mediates HLA class I up-regulation, which can be inhibited by the IL-6 pathway, in HLA-deficient Small Cell Lung Cancer cells

Background

Recently, immunotherapy with anti-PD-1 antibodies has shown clinical benefit in recurrent Small Cell Lung Cancer (SCLC). Since anti-PD-1 re-activates anti-tumor Cytotoxic T Lymphocyte (CTL) responses, it is crucial to understand the mechanisms regulating HLA class I, and PD-L1 expression in HLA-negative SCLC. Here we addressed the role of IL-27, a cytokine related to both IL-6 and IL-12 families.

Methods

The human SCLC cell lines NCI-N592, -H69, -H146, -H446 and -H82 were treated in vitro with different cytokines (IL-27, IFN-γ, IL-6 or a soluble IL-6R/IL-6 chimera [sIL-6R/IL-6]) at different time points and analyzed for tyrosine-phosphorylated STAT proteins by Western blot, for surface molecule expression by immunofluorescence and FACS analyses or for specific mRNA expression by QRT-PCR. Relative quantification of mRNAs was calculated by the ΔΔCT method. The Student’s T test was used for the statistical analysis of experimental replicates.

Results

IL-27 triggered STAT1/3 phosphorylation and up-regulated the expression of surface HLA class I antigen and of TAP1 and TAP2 mRNA in four out of five SCLC cell lines tested. The IL-27-resistant NCI-H146 cells showed up-regulation of HLA class I by IFN-γ. IFN-γ also induced expression of PD-L1 in SCLC cells, while IL-27 was less potent in this respect. IL-27 failed to activate STAT1/3 phosphorylation in NCI-H146 cells, which display a low expression of the IL-27RA and GP130 receptor chains. As GP130 is shared in IL-27R and IL-6R complexes, we assessed its functionality in response to sIL-6R/IL-6. sIL-6R/IL-6 failed to trigger STAT1/3 signaling in NCI-H146 cells, suggesting low GP130 expression or uncoupling from signal transduction. Although both sIL-6R/IL-6 and IL-27 triggered STAT1/3 phosphorylation, sIL-6R/IL-6 failed to up-regulate HLA class I expression, in relationship to the weak activation of STAT1. Finally sIL-6R/IL-6 limited IL-27-effects, particularly in NCI-H69 cells, in a SOCS3-independent manner, but did not modify IFN-γ induced HLA class I up-regulation.

Conclusions

In conclusion, IL-27 is a potentially interesting cytokine for restoring HLA class I expression for SCLC combined immunotherapy purposes. However, the concomitant activation of the IL-6 pathway may limit the IL-27 effect on HLA class I induction but did not significantly alter the responsiveness to IFN-γ.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0608-z) contains supplementary material, which is available to authorized users.

MHC class II expression in lung cancer

BACKGROUND

Immunotherapy is an exciting development in lung cancer research. In this study we described major histocompatibility complex (MHC) Class II protein expression in lung cancer cell lines and patient tissues.

METHODS

We studied MHC Class II (DP, DQ, DR) (CR3/43, Abcam) protein expression in 55 non-small cell lung cancer (NSCLC) cell lines, 42 small cell lung cancer (SCLC) cell lines and 278 lung cancer patient tissues by immunohistochemistry (IHC).

RESULTS

Seven (12.7%) NSCLC cell lines were positive for MHC Class II. No SCLC cell lines were found to be MHC Class II positive. We assessed 139 lung cancer samples available in the Hirsch Lab for MHC Class II. There was no positive MHC Class II staining on SCLC tumor cells. MHC Class II expression on TILs in SCLC was significantly lower than that on TILs in NSCLC (P＜0.001). MHC Class II was also assessed in an additional 139 NSCLC tumor tissues from Medical University of Gdansk, Poland. Patients with positive staining of MHC Class II on TILs had longer regression-free survival (RFS) and overall survival (OS) than those whose TILs were MHC Class II negative (2.980 years, 95% CI 1.628-4.332 vs. 1.050 years, 95% CI 0.556-1.554, P=0.028) (3.230 years, 95% CI 2.617-3.843 vs. 1.390 years, 95% CI 0.629-2.151, P=0.014).

CONCLUSIONS

MHC Class II was expressed both in NSCLC cell lines and tissues. However, MHC Class II was not detected in SCLC cell lines or tissue tumor cells. MHC Class II expression was lower on SCLC TILs than on NSCLC TILs. Loss of expression of MHC Class II on SCLC tumor cells and reduced expression on SCLC TILs may be a means of escaping anti-cancer immunity. Higher MHC Class II expression on TILs was correlated with better prognosis in patients with NSCLC.

Anthrax toxin receptor 1 is the cellular receptor for Seneca Valley virus

Seneca Valley virus (SVV) is an oncolytic picornavirus with selective tropism for neuroendocrine cancers. It has shown promise as a cancer therapeutic in preclinical studies and early-phase clinical trials. Here, we have identified anthrax toxin receptor 1 (ANTXR1) as the receptor for SVV using genome-wide loss-of-function screens. ANTXR1 is necessary for permissivity in vitro and in vivo. However, robust SVV replication requires an additional innate immune defect. We found that SVV interacts directly and specifically with ANTXR1, that this interaction is required for SVV binding to permissive cells, and that ANTXR1 expression is necessary and sufficient for infection in cell lines with decreased expression of antiviral IFN genes at baseline. Finally, we identified the region of the SVV capsid that is responsible for receptor recognition using cryoelectron microscopy of the SVV-ANTXR1-Fc complex. These studies identify ANTXR1, a class of receptor that is shared by a mammalian virus and a bacterial toxin, as the cellular receptor for SVV.

Genomic Profiling of Patient-Derived Xenografts for Lung Cancer Identifies B2M Inactivation Impairing Immunorecognition

Purpose: We aimed to maximize the performance of detecting genetic alterations in lung cancer using high-throughput sequencing for patient-derived xenografts (PDXs).Experimental Design: We undertook an integrated RNA and whole-exome sequencing of 14 PDXs. We focused on the genetic and functional analysis of β2-microglobulin (B2M), a component of the HLA class-I complex.Results: We identified alterations in genes involved in various functions, such as B2M involved in immunosurveillance. We extended the mutational analysis of B2M to about 230 lung cancers. Five percent of the lung cancers carried somatic mutations, most of which impaired the correct formation of the HLA-I complex. We also report that genes such as CALR, PDIA3, and TAP1, which are involved in the maturation of the HLA-I complex, are altered in lung cancer. By gene expression microarrays, we observed that restitution of B2M in lung cancer cells upregulated targets of IFNα/IFNγ. Furthermore, one third of the lung cancers lacked the HLA-I complex, which was associated with lower cytotoxic CD8⁺ lymphocyte infiltration. The levels of B2M and HLA-I proteins correlated with those of PD-L1. Finally, a deficiency in HLA-I complex and CD8⁺ infiltration tended to correlate with reduced survival of patients with lung cancer treated with anti-PD-1/anti-PD-L1.Conclusions: Here, we report recurrent inactivation of B2M in lung cancer. These observations, coupled with the mutations found at CALR, PDIA3, and TAP1, and the downregulation of the HLA-I complex, indicate that an abnormal immunosurveillance axis contributes to lung cancer development. Finally, our observations suggest that an impaired HLA-I complex affects the response to anti-PD-1/anti-PD-L1 therapies. Clin Cancer Res; 23(12); 3203-13. ©2016 AACR.

Different morphology, stage and treatment affect immune cell infiltration and long-term outcome in patients with non-small-cell lung carcinoma

AIMS

Development of effective immune-based therapies for patients with non-small-cell lung carcinoma (NSCLC) depends on an accurate characterization of complex interactions that occur between immune cells and the tumour environment.

METHODS AND RESULTS

Innate and adaptive immune responses were evaluated in relation to prognosis in 65 patients with surgically excised NSCLC. Immunohistochemistry and morphometry were used to determine the abundance and distribution of immune cells. We found low numbers of immune cells and levels of cytokines in the tumour environment when compared with surrounding parenchyma. Smoking was associated inversely with the adaptive immune response and directly with innate immunity. We observed a prominent adaptive immune response in squamous cell carcinomas (SCC) but greater innate immune responses in adenocarcinomas and large cell carcinomas. Cox model analysis showed a low risk of death for smoking <41 packs/year, N0 tambour stage, squamous carcinoma, CD4(+)  > 16.81% and macrophages/monocytes >4.5%. Collectively, the data indicate that in NSCLC there is not a substantive local immune cell infiltrate within the tumour.

CONCLUSION

Although immune cell infiltration is limited in NSCLC it appears to have an impact on prognosis and this may be of relevance for new immunotherapeutic approaches.

Prediction of Outcome in Diffuse Large Cell Lymphoma by the Major Histocompatibility Complex Class II (HLA-DR, DP, DQ) and Class I (HLA-A, B, C) Phenotype

Ninety-nine consecutive diffuse large cell lymphoma (DLCL) patients were studied by immunohistochemistry to determine whether clinical outcome was predicted by major histocompatibility complex (MHC) antigen phenotypic expression. Statistically significantly shorter disease free survival (p = 0.005), but not overall survival (p = 0.47), was observed when patient lymphomas failed to express class I MHC antigens. We also observed significantly reduced survival of class II MHC HLA-DP negative patients (p = 0.038). This extends our previous finding of poor outcome with absent class II MHC HLA-DR in DLCL(1) to other MHC antigens and demonstrates that the phenomenon of defective class II antigen expression comprises 16% of these DLCL patients. Known clinical parameters predictive of prognosis were equally distributed between phenotypic groups. These findings indicate that aberrancy of immune phenotype in DLCL is critical to patient outcome and we speculate that loss of MHC expression may confound host immunosurveillance and tumor containment.

Origins, genetic landscape, and emerging therapies of small cell lung cancer

Lung cancer is the leading cause of cancer deaths, with small cell lung cancer (SCLC) representing the most aggressive subtype. Standard treatments have not changed in decades, and the 5-year survival rate has remained <7%. Genomic analyses have identified key driver mutations of SCLC that were subsequently validated in animal models of SCLC. To provide better treatment options, a deeper understanding of the cellular and molecular mechanisms underlying SCLC initiation, progression, metastasis, and acquisition of resistance is required. In this review, we describe the genetic landscape of SCLC, features of the cell of origin, and targeted therapeutic approaches.

Favorable response to trastuzumab plus irinotecan combination therapy in two patients with HER2-positive relapsed small-cell lung cancer

Small-cell lung cancer (SCLC) easily recurs with multidrug resistance phenotype. However, standard therapeutic strategies for relapsed-SCLC remain unestablished. Human epidermal growth factor receptor 2 (HER2) expression correlates with poor prognosis in extensive disease-SCLC. We have reported previously that HER2 expression is upregulated when HER2-positive SCLC cells acquire chemoresistance, and also demonstrated that trastuzumab exerts significant antitumor activity toward HER2-upregulated chemoresistant SCLC, mainly via antibody-dependent cell-mediated cytotoxicity mechanism. Based on these preclinical data, we treated two patients with HER2-positive SCLC by combination of trastuzumab (6 mg/kg, day 1) and irinotecan (80 mg/m(2), days 1 and 8) every 21 days as the third-line chemotherapy following two prior regimens, first-line carboplatin plus etoposide and second-line amrubicin. One patient achieved partial response after the first cycle and received 6 cycles in total without disease progression for 4.5 months. The other also received 4 cycles and kept stable disease for 3.5 months. This treatment can be continued safely at an outpatient clinic without any severe adverse event. In conclusion, trastuzumab plus irinotecan chemotherapy is promising and feasible against HER2-positive relapsed SCLC. Further clinical studies are encouraged to confirm the antitumor efficacy of trastuzumab in SCLC.

Methylome analysis identifies a Wilms tumor epigenetic biomarker detectable in blood

BACKGROUND

Wilms tumor is the most common pediatric renal malignancy and there is a clinical need for a molecular biomarker to assess treatment response and predict relapse. The known mutated genes in this tumor type show low mutation frequencies, whereas aberrant methylation at 11p15 is by far the most common aberration. We therefore analyzed the epigenome, rather than the genome, to identify ubiquitous tumor-specific biomarkers.

RESULTS

Methylome analysis of matched normal kidney and Wilms tumor identifies 309 preliminary methylation variable positions which we translate into three differentially methylated regions (DMR) for use as tumor-specific biomarkers. Using two novel algorithms we show that these three DMRs are not confounded by cell type composition. We further show that these DMRs are not methylated in embryonic blastema but are intermediately methylated in Wilms tumor precursor lesions. We validate the biomarker DMRs using two independent sample sets of normal kidney and Wilms tumor and seven Wilms tumor histological subtypes, achieving 100% and 98% correct classification, respectively. As proof-of-principle for clinical utility, we successfully use biomarker DMR-2 in a pilot analysis of cell-free circulating DNA to monitor tumor response during treatment in ten patients.

CONCLUSIONS

These findings define the most common methylated regions in Wilms tumor known to date which are not associated with their embryonic origin or precursor stage. We show that this tumor-specific methylated DNA is released into the blood circulation where it can be detected non-invasively showing potential for clinical utility.

Genome-wide analysis of DNA methylation, copy number variation, and gene expression in monozygotic twins discordant for primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an uncommon autoimmune disease with a homogeneous clinical phenotype that reflects incomplete disease concordance in monozygotic (MZ) twins. We have taken advantage of a unique collection consisting of genomic DNA and mRNA from peripheral blood cells of female MZ twins (n = 3 sets) and sisters of similar age (n = 8 pairs) discordant for disease. We performed a genome-wide study to investigate differences in (i) DNA methylation (using a custom tiled four-plex array containing tiled 50-mers 19,084 randomly chosen methylation sites), (ii) copy number variation (CNV) (with a chip including markers derived from the 1000 Genomes Project, all three HapMap phases, and recently published studies), and/or (iii) gene expression (by whole-genome expression arrays). Based on the results obtained from these three approaches we utilized quantitative PCR to compare the expression of candidate genes. Importantly, our data support consistent differences in discordant twins and siblings for the (i) methylation profiles of 60 gene regions, (ii) CNV of 10 genes, and (iii) the expression of 2 interferon-dependent genes. Quantitative PCR analysis showed that 17 of these genes are differentially expressed in discordant sibling pairs. In conclusion, we report that MZ twins and sisters discordant for PBC manifest particular epigenetic differences and highlight the value of the epigenetic study of twins.

Genome-wide analysis of DNA methylation, copy number variation, and gene expression in monozygotic twins discordant for primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an uncommon autoimmune disease with a homogeneous clinical phenotype that reflects incomplete disease concordance in monozygotic (MZ) twins. We have taken advantage of a unique collection consisting of genomic DNA and mRNA from peripheral blood cells of female MZ twins (n = 3 sets) and sisters of similar age (n = 8 pairs) discordant for disease. We performed a genome-wide study to investigate differences in (i) DNA methylation (using a custom tiled four-plex array containing tiled 50-mers 19,084 randomly chosen methylation sites), (ii) copy number variation (CNV) (with a chip including markers derived from the 1000 Genomes Project, all three HapMap phases, and recently published studies), and/or (iii) gene expression (by whole-genome expression arrays). Based on the results obtained from these three approaches we utilized quantitative PCR to compare the expression of candidate genes. Importantly, our data support consistent differences in discordant twins and siblings for the (i) methylation profiles of 60 gene regions, (ii) CNV of 10 genes, and (iii) the expression of 2 interferon-dependent genes. Quantitative PCR analysis showed that 17 of these genes are differentially expressed in discordant sibling pairs. In conclusion, we report that MZ twins and sisters discordant for PBC manifest particular epigenetic differences and highlight the value of the epigenetic study of twins.

Immune checkpoint blockade: the hope for immunotherapy as a treatment of lung cancer?

Over the past 20 years, immunotherapy has not played a role in the treatment of lung cancer outside of clinical trials. Early trials with vaccines yielded promising results, but phase III trials have yet to show an improvement in survival. Recently, immune checkpoint pathway inhibitors have yielded exciting and consistent activity across this class of antibodies. However, phase III trials are now ongoing. Currently, the hope of bringing immunotherapy to lung cancer patients lies in this class of drugs. Only time will show us if these antibodies will yield an improvement in long-term survival. This review will focus on checkpoint pathway inhibitors that have completed early-phase trials.

Lung cancer: a classic example of tumor escape and progression while providing opportunities for immunological intervention

Lung cancers remain one of the most common and deadly cancers in the world today (12.5% of newly diagnosed cancers) despite current advances in chemo- and radiation therapies. Often, by the time these tumors are diagnosed, they have already metastasized. These tumors demonstrate the classic hallmarks of cancer in that they have advanced defensive strategies allowing them to escape various standard oncological treatments. Immunotherapy is making inroads towards effectively treating other fatal cancers, such as melanoma, glioblastoma multiforme, and castrate-resistant prostate cancers. This paper will cover the escape mechanisms of bronchogenic lung cancer that must be overcome before they can be successfully treated. We also review the history of immunotherapy directed towards lung cancers.

Paclitaxel and TRAIL synergize to kill paclitaxel-resistant small cell lung cancer cells through a caspase-independent mechanism mediated through AIF

BACKGROUND

Small cell lung cancer (SCLC) is the most aggressive form of lung cancer with poor disease outcome. The chemotherapeutic agent paclitaxel (PA) is commonly used as a second-line treatment in SCLC, but response rates are low.

MATERIALS AND METHODS

86M1 SCLC cells were treated in the presence or absence of paclitaxel and TRAIL or the combination for 24 hours. Western blot analysis was utilized to examine protein expression, cell surface protein expression and membrane integrity were elucidated by flow cytometry, and immunofluorescence microscopy was used to demonstrate translocation of proteins to the cell nucleus.

RESULTS

Human 86M1 SCLC cells were found to be resistant to PA killing in vitro. This resistance is mediated by up-regulation of pro-survival protein BCL-xl. However, PA also increases surface expression of death receptors 4 and 5 (DR4 and DR5, respectively). The death receptors' ligand increased SCLC killing by PA through an apparent caspase-independent route involving activation/translocation of AIF.

CONCLUSION

The addition of TRAIL to PA can potentiate apoptosis in a relatively PA-resistant SCLC line (specifically 86M1 cells). More importantly, we are the first to report an active method of resistance to paclitaxel in SCLC via BCL-xl up-regulation.

Effects of fumonisin B1 on HLA class I antigen presentation and processing pathway in GES-1 cells in vitro

Fumonisin B1 (FB1) is a food-borne mycotoxin produced by genus Fusarium and was classified as possible carcinogen to humans by the International Agency for Research on Cancer (IARC). Human leukocyte antigen (HLA) class I antigen presentation pathway plays an important role in immunosurveillance. Defects in HLA class I antigen presentation pathway can down-regulate the expression of HLA class I antigen on the surface of nucleated cells that will confer a survival advantage to randomly mutant cells and may lead to malignant transformation. In the present study, we analyzed the effects of FB1 on the expression of HLA class I heavy chain (classical HLA-A, -B and -C genes included), beta2-microglobulin (β2m), LMP2 and TAP1 genes in human gastric epithelial immortalized GES-1 cells in vitro using semi-quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR), Western blot and immunocytochemical methods in dose- and time-effect studies. Our results revealed that FB1 have an effect on HLA class I antigen presentation pathway via the decreased expression of HLA class I heavy chain and/or defects of LMP2 and TAP1 expression. However, the importance of this effect in carcinogenesis needs further investigation.

Combined modality immunotherapy and chemotherapy: a new perspective

The results of recent clinical trials have demonstrated that cancer vaccines continue to struggle to achieve tangible clinical benefits as monotherapy. Tumor-induced abnormalities in the immune system hamper anti-tumor T cell responses limiting the effectiveness of cancer immunotherapy. Recently, evidence has been mounting to suggest that immunotherapy has the possibility of achieving better success when used in combination with conventional chemotherapy. In clinical trials, immune responses elicited by cancer vaccines appear to augment the effectiveness of subsequent conventional cancer therapies.

High frequency of immature dendritic cells and altered in situ production of interleukin-4 and tumor necrosis factor-alpha in lung cancer

INTRODUCTION

Antigen-presenting cells, like dendritic cells (DCs) and macrophages, play a significant role in the induction of an immune response and an imbalance in the proportion of macrophages, immature and mature DCs within the tumor could affect significantly the immune response to cancer. DCs and macrophages can differentiate from monocytes, depending on the milieu, where cytokines, like interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) induce DC differentiation and tumor necrosis factor (TNF)-alpha induce DC maturation. Thus, the aim of this work was to analyze by immunohistochemistry the presence of DCs (S100+ or CD1a+), macrophages (CD68+), IL-4 and TNF-alpha within the microenvironment of primary lung carcinomas.

RESULTS

Higher frequencies of both immature DCs and macrophages were detected in the tumor-affected lung, when compared to the non-affected lung. Also, TNF-alpha-positive cells were more frequent, while IL-4-positive cells were less frequent in neoplastic tissues. This decreased frequency of mature DCs within the tumor was further confirmed by the lower frequency of CD14-CD80+ cells in cell suspensions obtained from the same lung tissues analyzed by flow cytometry.

CONCLUSION

These data are discussed and interpreted as the result of an environment that does not oppose monocyte differentiation into DCs, but that could impair DC maturation, thus affecting the induction of effective immune responses against the tumor.

Concordant expression of proto-oncogene promyelocytic leukemia and major histocompatibility antigen HLA class I in human hepatocellular carcinoma

Many malignant cancer cells downregulate human leukocyte antigen (HLA) class I antigen expression to evade T cell recognition. However, hepatocellular carcinoma (HCC) is exceptional to the general findings in cancer cells, and the mechanisms for its upregulation remain unclear. It has been reported that promyelocytic leukemia (PML) proto-oncogene controls the transcription of multiple class I antigen presentation genes in murine cancer cells. To find out the functional role of PML gene on the increased HLA class I antigen expression in HCC cells, we analyzed the expression of proto-oncogene PML and multiple class I antigen presentation genes in HCC specimens obtained in China. The results showed concordant changes of proto-oncogene PML and cell surface HLA-A expression in 44 paraffin-embedded HCC tissues. Furthermore, co-upregulated expression of PML genes and class I antigen presentation genes could be detected in 9 of 15 fresh HCC tissues by reverse transcription polymerase chain reaction (RT-PCR). In addition, studies using HCC cell lines showed that increased expression of HLA class I molecules paralleled with PML upregulation were detected in QGY-7701 HCC cell line with RT-PCR, western blot, and flow cytometry, and that the overexpression of exogenous PML in a low-expression class I cell line BEL-7405 could induce the expression of multiple class I antigen-presenting molecule genes and slightly but significantly increase the expression of cell surface HLA class I molecules. In conclusion, the expression of proto-oncogene PML and HLA class I molecules were concordantly upregulated and the expression of PML gene might be one of the mechanisms that leads to the increased expression of class I antigen in HCC.

Targeting tumour cells with defects in the MHC Class I antigen processing pathway with CD8+ T cells specific for hydrophobic TAP- and Tapasin-independent peptides: the requirement for directed access into the ER

It is becoming increasingly apparent that the majority of tumours display defects in the MHC class I antigen processing pathway, particularly low levels of the transporters-associated with antigen processing (TAP) and tapasin. Thus, immunotherapy approaches targeting such tumours with CD8+ cytotoxic T lymphocytes (CTL) requires strategies to overcome these defects. Previously we had identified an antigen processing pathway by which cytosolically derived hydrophobic peptides could be presented in the absence of TAP. Here we show in the tapasin-negative cell line 721.220 that a number of these hydrophobic TAP-independent peptides can also be presented in a tapasin-independent manner. Yet when these experiments were extended to tumour cell lines derived from small cell lung cancer (SCLC), which we show to be tapasin deficient in addition to TAP-negative, the TAP-, tapasin-independent peptides were not presented. This lack of presentation could be rectified by pre-treatment of SCLC cells with IFNgamma. Alternatively, by directing the TAP-, tapasin-independent peptides into the endoplasmic reticulum (ER) via an ER signal sequence, these peptides were presented efficiently by SCLC cells. We infer from this data that the TAP-independent pathway for presentation of hydrophobic peptides generates a low concentration of peptide in the ER and, for tumour cells which also lack tapasin, this concentration of antigenic peptide is insufficient to load onto MHC class I molecules. Thus, for immunotherapeutic approaches to target SCLC and other tumours with defects in the MHC class I antigen processing pathway it will be important to consider strategies that address tapasin-defects.

Clinical relevance of soluble HLA-I and beta2-microglobulin levels in non-Hodgkin's lymphoma and Hodgkin's disease

Plasma levels of beta-2 microglobulin (beta2M), a subunit of the human leukocyte antigen-class I (HLA-I) molecule, correlate negatively with outcome in non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD). We examined the clinical relevance of soluble HLA-I (sHLA-I) levels in NHL and HD. Sera from consecutive NHL (n=65) and HD (n=37) patients were analyzed in a blinded manner. NHL and HD patients had significantly higher levels of sHLA-1 and beta2M than control subjects. In NHL patients, sHLA-I levels correlated with clinical behavior in a fashion similar to that of beta2M. However, multivariate analysis incorporating beta2M, sHLA-I, and international prognostic index (IPI) indicated that NHL patients with elevated (>312.6mug/100mL) sHLA-I levels had significantly shorter survival, independent of IPI score as well as beta2M. In HD patients, beta2M but not sHLA-I levels were associated with clinical behavior. These findings not only establish the role of sHLA-I as an independent tumor marker in NHL that can be used to stratify patients, but also suggest that beta2M and sHLA-I may reflect different biological processes in HD and NHL. Further studies are needed to assess whether the immunomodulatory properties of sHLA-I may be responsible for its divergence from beta2M as an indicator of clinical behavior in HD.

Mechanisms of immune evasion by tumors

In the past decade, basic studies in animal models have begun to elucidate the physiological barriers which impede a successful antitumor immune response. These barriers operate at a number of levels, and involve the tumor, the tumor microenvironment and various components of the innate and adaptive immune systems. In this review, we discuss the multiple mechanisms by which tumors evade an immune response, with an emphasis on clinically relevant strategies to overcome these inhibitory checkpoints.

Downregulation of major histocompatibility complex antigens in invading glioma cells: stealth invasion of the brain

Invasion into surrounding brain tissue is a fundamental feature of gliomas and the major reason for treatment failure. The process of brain invasion in gliomas is not well understood. Differences in gene expression and/or gene products between invading and noninvading glioma cells may identify potential targets for new therapies. To look for genes associated with glioma invasion, we first employed Affymetrix microarray Genechip technology to identify genes differentially expressed in migrating glioma cells in vitro and in invading glioma cells in vivo using laser capture microdissection. We observed upregulation of a variety of genes, previously reported to be linked to glioma cell migration and invasion. Remarkably, major histocompatiblity complex (MHC) class I and II genes were significantly downregulated in migrating cells in vitro and in invading cells in vivo. Decreased MHC expression was confirmed in migrating glioma cells in vitro using RT-PCR and in invading glioma cells in vivo by immunohistochemical staining of human and murine glioblastomas for beta2 microglobulin, a marker of MHC class I protein expression. To the best of our knowledge, this report is the first to describe the downregulation of MHC class I and II antigens in migrating and invading glioma cells, in vitro and in vivo, respectively. These results suggest that the very process of tumor invasion is associated with decreased expression of MHC antigens allowing glioma cells to invade the surrounding brain in a 'stealth'-like manner.

Urine dendritic cells: a noninvasive probe for immune activity in bladder cancer?

OBJECTIVES

To test the hypothesis that dendritic cells (DC), antigen-presenting cells with the potential to stimulate primary T-cell responses, may appear in the urine of patients with bladder cancer, and that their characteristics may reflect those of DC in cancer tissue.

PATIENTS AND METHODS

Cells from digested tissue of transurethral resection specimens from eight patients and urine from 18 with bladder cancers were analysed using flow cytometry, immunohistochemistry and electron microscopy. Urine samples from 12 patients were also analysed during intravesical bacillus Calmette-Guerin (BCG) therapy.

RESULTS

Immature DC positive for major histocompatibility complex class II antigens, negative for markers of other leukocyte lineages and with low levels of co-stimulatory markers, were identified in CD45-positive cells isolated immediately from cancer tissue or amongst cells migrating from tissue fragments after overnight culture. Immature-phenotype DC were also identified in the urine of patients with bladder cancer. Their identity was confirmed by immunohistochemistry and electron microscopy. Using these methods, DC were monitored from the bladder during BCG installation for bladder cancer in 12 patients for a mean of 10 months. Of six patients who developed a recurrence of their bladder cancer over this period, all but one showed a lower percentage of DC in their urine at the end of their initial treatment.

CONCLUSION

We identified DC in the urine of patients with bladder cancer for the first time. We speculate that variability in the percentage of urinary DC may reflect changes in immunological activity at the tumour site; prospective studies are required to evaluate the relevance of these DC counts and characteristics to clinical outcome.

Does the immune system see tumors as foreign or self?

Given the vast number of genetic and epigenetic changes associated with carcinogenesis, it is clear that tumors express many neoantigens. A central question in cancer immunology is whether recognition of tumor antigens by the immune system leads to activation (i.e., surveillance) or tolerance. Paradoxically, while strong evidence exists that specific immune surveillance systems operate at early stages of tumorigenesis, established tumors primarily induce immune tolerance. A unifying hypothesis posits that the fundamental processes of cancer progression, namely tissue invasion and metastasis, are inherently proinflammatory and thus activating for innate and adaptive antitumor immunity. To elude immune surveillance, tumors must develop mechanisms that block the elaboration and sensing of proinflammatory danger signals, thereby shifting the balance from activation to tolerance induction. Elucidation of these mechanisms provides new strategies for cancer immunotherapy.

Expression of tetraspanins in human lung cancer cells: frequent downregulation of CD9 and its contribution to cell motility in small cell lung cancer

Small cell lung cancer (SCLC) invades locally and metastasizes distantly extremely early when compared with nonsmall cell lung cancer (NSCLC). The underlying molecular mechanisms, however, have not been elucidated. Accumulating evidence suggests that downregulation of several members of tetraspanins is associated with progression of solid tumors, thus indicating poor prognosis. Here we screened 30 lung cancer cell lines for expression of tetraspanins, CD9, CD63, CD81, CD82, CD151, and NAG-2. Flow cytometry revealed that, among these proteins, CD9 is broadly expressed in NSCLC lines, but is absent or highly reduced in most SCLC lines (P<0.0001). Using the Boyden chamber and videomicroscopic cell motility assays, we showed that stable transfection of CD9 into an SCLC line, OS3-R5, reduced cell motility on fibronectin. Furthermore, by transient transfection of green fluorescent protein (GFP)-tagged CD9 into three other SCLC lines, we observed that SCLC cells expressing GFP-CD9 were uniformly less motile than untransfected cells. CD9 or GFP-CD9 was associated with beta1 integrins and distributed at the tumor cell periphery and cell-cell contacts, suggesting that CD9 modifies beta1 integrin function to reduce motility. These findings suggest that low expression of CD9 may contribute to the highly invasive and metastatic phenotype of SCLC.