Malignant Mesothelioma Effusions Are Infiltrated by CD3+ T Cells Highly Expressing PD-L1 and the PD-L1+ Tumor Cells within These Effusions Are Susceptible to ADCC by the Anti-PD-L1 Antibody Avelumab

JAVELIN Head and Neck 100: a Phase III trial of avelumab and chemoradiation for locally advanced head and neck cancer

Chemoradiotherapy (CRT) is the standard of care for locoregionally advanced squamous cell carcinomas of the head and neck (HNSCC). The immune checkpoint inhibitors nivolumab and pembrolizumab were recently approved by the US FDA for treatment of recurrent or metastatic HNSCC that are refractory to platinum chemotherapy. However, prospective studies incorporating immune checkpoint inhibitors in the definitive management of poor prognosis, nonmetastatic, locoregionally advanced HNSCC are lacking. The JAVELIN Head and Neck 100 study is a multinational, Phase III, double-blind, placebo-controlled, randomized clinical trial assessing the efficacy of avelumab, a PD-L1 inhibitor, in combination with CRT compared with placebo in combination with CRT for high-risk HNSCC. Trial registration: Javelin Head and Neck 100; NCT 02952586.

High BIN1 expression has a favorable prognosis in malignant pleural mesothelioma and is associated with tumor infiltrating lymphocytes

OBJECTIVES

A number of key immune regulators show prognostic value in malignant pleural mesothelioma (MPM), but the association between Bridging integrator 1 (BIN1), indoleamine 2,3 dioxygenase 1 (IDO1) and patient outcome has not been investigated. We aimed to determine the expression of BIN1 and IDO1, their association with other markers and impact on overall survival (OS) in MPM.

MATERIALS AND METHODS

The expression of BIN1, IDO1, CD3, CD20 and CD68 were evaluated by immunohistochemistry in 67 patients who underwent pleurectomy/decortication. Survival analyses were performed using the Kaplan Meier method and significant biomarkers were entered into a Cox Regression multivariate model, accounting for known prognostic factors such as age, gender, histological subtype, PD-L1 expression and neutrophil-to-lymphocyte ratio.

RESULTS

Immune markers were variably expressed in tumor cells, ranging from 0% to 100% for BIN1 (median: 89%), and 0% to 77.5% for IDO1 (median: 0%). Expression of markers of tumor-infiltrating lymphocytes (TILs) and macrophages ranged from 0% to more than 50%. BIN1 expression was high in 35 patients (51%) and was associated with increased OS (median: 12 vs 6 months for high and low BIN1 respectively,p = 0.03). Multivariate analysis showed BIN1 remained an independent prognostic indicator (HR 0.39; 95% CI: 0.18-0.82, p = 0.01). The majority of patients had immune inflamed tumors (77%) and there was a significant association between TILs and BIN1 (p = 0 < 0.01), PD-L1 (p=0.04) and CD68+ macrophages in the tumor (p < 0.01). There were no significant associations between PD-L1 and BIN1 or IDO1.

CONCLUSION

High BIN1 expression is a favorable prognostic biomarker and is associated with TILs in MPM.

A review of avelumab in locally advanced and metastatic bladder cancer

Urothelial carcinoma remains a devastating disease with a poor prognosis. Though immune therapy with Bacillus Calmette–Guérin (BCG) has been used for localized bladder cancer for years, only immune-checkpoint blockade with antiprogrammed cell-death 1 (anti-PD-1) and antiprogrammed cell-death ligand 1 (anti-PD-L1) inhibitors have demonstrated improvement in survival of patients with metastatic disease. Anti-PD-L1 antibody, avelumab, was recently given United States Food and Drug Administration (FDA) accelerated approval for the treatment of recurrent/metastatic urothelial carcinoma after failure of first-line chemotherapy, marking the fifth immune checkpoint inhibitor to be given FDA approval for the treatment of metastatic urothelial cancer. The following manuscript will review avelumab, its pharmacology, and the clinical experience that has led to its approval, as well as future plans for clinical development of avelumab for the treatment or urothelial cancer.

Making cold malignant pleural effusions hot: driving novel immunotherapies

Malignant pleural effusions, arising from either primary mesotheliomas or secondary malignancies, heralds advanced disease and poor prognosis. Current treatments, including therapeutic thoracentesis and tube thoracostomy, are largely palliative. The immunosuppressive environment within the pleural cavity includes myeloid derived suppressor cells, T-regulatory cells, and dysfunctional T cells. The advent of effective immunotherapy with checkpoint inhibitors and adoptive cell therapies for lung cancer and other malignancies suggests a renewed examination of local and systemic therapies for this malady. Prior strategies reporting remarkable success, including instillation of the cytokine interleukin-2, perhaps coupled with checkpoint inhibitors, should be further evaluated in the modern era.

Immunotherapy strategies for mesothelioma - the role of tumor specific neoantigens in a new era of precision medicine

INTRODUCTION

Immunotherapy has long been considered a potential therapy for malignant mesothelioma and is currently being pursued as such. Some of the early phase clinical trials involving immunomodulators have demonstrated encouraging results and numerous clinical trials are underway to further investigate this treatment approach in various treatment settings and larger patient cohorts. Areas covered: This review summarizes the current and emerging clinical evidence for checkpoint blockade and other immunotherapeutic strategies in mesothelioma. The mesothelioma tumor immune microenvironment and mutational landscape are also discussed, including their impact on treatment strategies. We also provide an evaluation of the current evidence for neoantigen targeted personalized immunotherapy. Expert opinion: Immune checkpoint inhibitors work by unleashing the host immune response against probable neoantigens. Despite impressive activity in a small subset of patients and the potential for prolonged responses, most patients experience treatment failure. Neoantigen vaccines provide a potential complementary therapeutic strategy by increasing the immunogenic antigen load, which can lead to an increased tumor specific immune response. Further research is needed explore this treatment option in mesothelioma and technological advances are required to translate this concept into clinical practice.

Tumour associated lymphocytes in the pleural effusions of patients with mesothelioma express high levels of inhibitory receptors

OBJECTIVE

Pleural effusion (PE) is a common feature of malignant pleural mesothelioma. These effusions typically contain lymphocytes and malignant cells. We postulated that the PE would be a source of lymphocytes for analysis of tumor immune milieu. The aim of this study was to compare the phenotype and T cell receptor usage of pleural effusion T cells with paired concurrently drawn peripheral blood lymphocytes. We used multi-parameter flow cytometry and high-throughput T cell receptor sequencing to analyse peripheral blood and pleural effusion mononuclear cells.

RESULTS

Both CD8⁺ and CD4⁺ T cells from effusion showed increased expression of T cell inhibitory receptors PD-1, LAG-3 and Tim-3 compared to blood. Comprehensive T cell receptor sequencing on one of the patients showed a discordant distribution of clonotypes in the antigen-experienced (PD-1⁺) compartment between effusion and blood, suggesting an enrichment of antigen specific clonotypes in the effusion, with potential as an immunological response biomarker.

Programmed cell death protein-1/programmed death-ligand 1 blockade enhances the antitumor efficacy of adoptive cell therapy against non-small cell lung cancer

Background

Cytokine-induced killer (CIK) cells and natural killer (NK) cells are employed by two different approaches to adoptive cell immunotherapy for cancer. It has been reported that adoptive cell immunotherapy could prolong the overall survival (OS) of advanced cancer patients. The introduction of agents that induce immune checkpoint blockades has improved the efficacy of immune-mediated therapy for metastatic cancers. However, the effects of combining a checkpoint inhibitor with CIK cells or NK cells to target non-small cell lung cancer (NSCLC)remain unknown.

Methods

The present study investigated the effects of combining CIK cells with a programmed cell death protein-1 (PD-1) inhibitor (an anti-PD-1 monoclonal antibody). During the expansion cultivation, the addition of the PD-1 antibody promoted CIK-mediated cytotoxicity in H1975 lung adenocarcinoma cells. Co-cultivation of CIK cells with the PD-1 antibody for 6 days induced CD3⁺CD56⁺ T cell expansion, with increases in the levels of CD107a and interferon γ (IFN-γ).

Results

When NK cells were co-cultured with 5 µg/mL of an anti-programmed death-ligand 1 (PD-L1) mAb for 24 hours at an effector cell: target ratio of 10:1, it led to more potent cytotoxicity compared to other time points and concentrations. However, combining NK cells with the anti-PD-L1 mAb showed no significant advantages over treatment with NK cells alone.

Conclusions

Our results suggest that combining CIK cells with PD-1 blockade before transfusion might improve the efficiency of CIK therapy for NSCLC patients. This effect does not seem to occur for NK cell therapy.

The multi-functionality of N-809, a novel fusion protein encompassing anti-PD-L1 and the IL-15 superagonist fusion complex

Here we describe a novel bifunctional fusion protein, designated N-809. This molecule comprises the IL-15/IL15Rα superagonist complex containing the Fc-domain of IgG1 (N-803, formerly designated as ALT-803) fused to two single chain anti-PD-L1 domains. The fully human IgG1 portion of the N-809 molecule was designed to potentially mediate antibody dependent cellular cytotoxicity (ADCC). The studies reported here show that N-809 has the same ability to bind PD-L1 as an anti-PD-L1 monoclonal antibody. RNAseq studies show the ability of N-809 to alter the expression of an array of genes of both CD4+ and CD8+ human T cells, and to enhance their proliferation; CD8+ T cells exposed to N-809 also have enhanced ability to lyse human tumor cells. An array of genes was differentially expressed in human natural killer (NK) cells following N-809 treatment, and there was increased expression of several surface activating receptors; there was, however, no increase in the expression of inhibitory receptors known to be upregulated in exhausted NK cells. N-809 also increased the cytotoxic potential of NK cells, as shown by increased expression of granzyme B and perforin. The lysis of several tumor cell types was increased when either NK cells or tumor cells were exposed to N-809. Similarly, the highest level of ADCC was seen when both NK cells (from donors or cancer patients) and tumor cells were exposed to N-809. These studies thus demonstrate the multi-functionality of this novel agent.

FcγR interaction is not required for effective anti-PD-L1 immunotherapy but can add additional benefit depending on the tumor model

Immunomodulatory antibodies blocking interactions of coinhibitory receptors to their ligands such as CTLA-4, PD1 and PD-L1 on immune cells have shown impressive therapeutic efficacy in clinical studies. The therapeutic effect of these antibodies is mainly mediated by reactivating antitumor T cell immune responses. Detailed analysis of anti-CTLA4 antibody therapy revealed that an optimal therapeutic efficacy also requires binding to Fc receptors for IgG, FcγR, mediating depletion of intratumoral regulatory T cells. Here, we investigated the role of Fc binding in anti-PD-L1 antibody therapy in the MC38 C57BL/6 and CT26 BALB/c colon adenocarcinoma tumor models. In the MC38 tumor model, all IgG subclasses anti-PD-L1 showed similar therapeutic efficacy when compared to each other in either wild-type mice or in mice deficient for all FcγR. In contrast, in the CT26 tumor model, anti-PD-L1 mIgG2a, the IgG subclass with the highest affinity for activating FcγR, showed stronger therapeutic efficacy than other IgG subclasses. This was associated with a reduction of a myeloid cell subset with high expression of PD-L1 in the tumor microenvironment. This subclass preference for mIgG2a was lost in C57BL/6 × BALB/c F1 mice, indicating that the genetic background of the host may determine the additional clinical benefit of the high affinity antibody subclasses. Based on these data, we conclude that FcγR are not crucial for anti-PD-L1 antibody therapy but might play a role in some tumor models.

Complex Immune Contextures Characterise Malignant Peritoneal Mesothelioma: Loss of Adaptive Immunological Signature in the More Aggressive Histological Types

Malignant peritoneal mesothelioma (MpM), arising in the setting of local inflammation, is a rare aggressive tumour with a poor prognosis and limited therapeutic options. The three major MpM histological variants, epithelioid (E-MpMs), biphasic, and sarcomatoid MpMs (S-MpMs), are characterised by an increased aggressiveness and enhanced levels of EZH2 expression. To investigate the MpM immune contexture along the spectrum of MpM histotypes, an extended in situ analysis was performed on a series of 14 cases. Tumour-infiltrating immune cells and their functionality were assessed by immunohistochemistry, immunofluorescence, qRT-PCR, and flow cytometry analysis. MpMs are featured by a complex immune landscape modulated along the spectrum of MpM variants. Tumour-infiltrating T cells and evidence for pre-existing antitumour immunity are mainly confined to E-MpMs. However, Th1-related immunological features are progressively impaired in the more aggressive forms of E-MpMs and completely lost in S-MpM. Concomitantly, E-MpMs show also signs of active immune suppression, such as the occurrence of Tregs and Bregs and the expression of the immune checkpoint inhibitory molecules PD1 and PDL1. This study enriches the rising rationale for immunotherapy in MpM and points to the E-MpMs as the most immune-sensitive MpM histotypes, but it also suggests that synergistic interventions aimed at modifying the tumour microenvironment (TME) should be considered to make immunotherapy beneficial for these patients.

Avelumab in patients with previously treated metastatic adrenocortical carcinoma: phase 1b results from the JAVELIN solid tumor trial

Background

We assessed the efficacy and safety of avelumab, an anti-programmed death ligand 1 (PD-L1) antibody, in patients with previously treated metastatic adrenocortical carcinoma (mACC).

Methods

In this phase 1b expansion cohort, patients with mACC and prior platinum-based therapy received avelumab at 10 mg/kg intravenously every 2 weeks. Continuation of mitotane was permitted; however, mitotane levels during the study were not recorded. Tumor response was assessed by Response Evaluation Criteria In Solid Tumors v1.1.

Results

Fifty patients received avelumab and were followed for a median of 16.5 months. Prior treatment included ≥2 lines in 74.0%; mitotane was continued in 50.0%. The objective response rate (ORR) was 6.0% (95% CI, 1.3% to 16.5%; partial response in 3 patients). Twenty-one patients (42.0%) had stable disease as best response (disease control rate, 48.0%). Median progression-free survival was 2.6 months (95% CI, 1.4 to 4.0), median overall survival (OS) was 10.6 months (95% CI, 7.4 to 15.0), and the 1-year OS rate was 43.4% (95% CI, 27.9% to 57.9%). In evaluable patients with PD-L1+ (n = 12) or PD-L1− (n = 30) tumors (≥5% tumor cell cutoff), ORR was 16.7% vs 3.3% (P = .192). Treatment-related adverse events (TRAEs) occurred in 82.0%; the most common were nausea (20.0%), fatigue (18.0%), hypothyroidism (14.0%), and pyrexia (14.0%). Grade 3 TRAEs occurred in 16.0%; no grade 4 to 5 TRAEs occurred. Twelve patients (24.0%) had an immune-related TRAE of any grade, which were grade 3 in 2 patients (4.0%): adrenal insufficiency (n = 1), and pneumonitis (n = 1).

Conclusions

Avelumab showed clinical activity and a manageable safety profile in patients with platinum-treated mACC.

Trial registration

Clinicaltrials.gov NCT01772004; registered January 21, 2013.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0424-9) contains supplementary material, which is available to authorized users.

Immune checkpoint blockade therapy of mesothelioma: a clinical and radiological challenge

Treatment of malignant pleural mesothelioma (MPM) represents a highly unmet medical need. Here, we discuss the results and therapeutic potential of first- and second-generation immunomodulatory antibodies targeting distinct immune checkpoints for the treatment of MPM, as well as their prospective therapeutic role in combination strategies. We also discuss the role of appropriate radiological criteria of response for MPM and the potential need of ad hoc criteria of disease evaluation in MPM patients undergoing treatment with immunotherapeutic agents.

CONFIRM: a double-blind, placebo-controlled phase III clinical trial investigating the effect of nivolumab in patients with relapsed mesothelioma: study protocol for a randomised controlled trial

BACKGROUND

Mesothelioma is an incurable, apoptosis-resistant cancer caused in most cases by previous exposure to asbestos and is increasing in incidence. It represents a growing health burden but remains under-researched, with limited treatment options. Early promising signals of activity relating to both PD-L1- and PD-1-targeted treatment in mesothelioma implicate a dependency of mesothelioma on this immune checkpoint. There is a need to evaluate checkpoint inhibitors in patients with relapsed mesothelioma where treatment options are limited.

METHODS

The addition of 12 months of nivolumab (anti-PD1 antibody) to standard practice will be conducted in the UK using a randomised, placebo-controlled phase III trial (the Cancer Research UK CONFIRM trial). A total of 336 patients with pleural or peritoneal mesothelioma who have received at least two prior lines of therapy will be recruited from UK secondary care sites. Patients will be randomised 2:1 (nivolumab:placebo), stratified according to epithelioid/non-epithelioid, to receive either 240 mg nivolumab monotherapy or saline placebo as a 30-min intravenous infusion. Treatment will be for up to 12 months. We will determine whether the use of nivolumab increases overall survival (the primary efficacy endpoint). Secondary endpoints will include progression-free survival, objective response rate, toxicity, quality of life and cost-effectiveness. Analysis will be performed according to the intention-to-treat principle using a Cox regression analysis for the primary endpoint (and for other time-to-event endpoints).

DISCUSSION

The outcome of this trial will provide evidence of the potential benefit of the use of nivolumab in the treatment of relapsed mesothelioma. If found to be clinically effective, safe and cost-effective it is likely to become the new standard of care in the UK.

TRIAL REGISTRATION

EudraCT Number: 2016-003111-35 (entered on 21 July 2016); ClinicalTrials.gov, ID: NCT03063450 . Registered on 24 February 2017.

Heterogeneity in Immune Cell Content in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive cancer with limited therapy options and dismal prognosis. In recent years, the role of immune cells within the tumor microenvironment (TME) has become a major area of interest. In this review, we discuss the current knowledge of heterogeneity in immune cell content and checkpoint expression in MPM in relation to prognosis and prediction of treatment efficacy. Generally, immune-suppressive cells such as M2 macrophages, myeloid-derived suppressor cells and regulatory T cells are present within the TME, with extensive heterogeneity in cell numbers. Infiltration of effector cells such as cytotoxic T cells, natural killer cells and T helper cells is commonly found, also with substantial patient to patient heterogeneity. PD-L1 expression also varied greatly (16-65%). The infiltration of immune cells in tumor and associated stroma holds key prognostic and predictive implications. As such, there is a strong rationale for thoroughly mapping the TME to better target therapy in mesothelioma. Researchers should be aware of the extensive possibilities that exist for a tumor to evade the cytotoxic killing from the immune system. Therefore, no "one size fits all" treatment is likely to be found and focus should lie on the heterogeneity of the tumors and TME.

Loss of C/EBP-β LIP drives cisplatin resistance in malignant pleural mesothelioma

OBJECTIVES

Cisplatin-based chemotherapy is moderately active in malignant pleural mesothelioma (MPM) due to intrinsic drug resistance and to low immunogenicity of MPM cells. CAAT/enhancer binding protein (C/EBP)-β LIP is a pro-apoptotic and chemosensitizing transcription factor activated in response to endoplasmic reticulum (ER) stress.

MATERIALS AND METHODS

We investigated if LIP levels can predict the clinical response to cisplatin and survival of MPM patients receiving cisplatin-based chemotherapy. We studied the LIP-dependent mechanisms determining cisplatin-resistance and we identified pharmacological approaches targeting LIP, able to restore cisplatin sensitiveness, in patient-derived MPM cells and animal models. Results were analyzed by a one-way analysis of variance test.

RESULTS

We found that LIP was degraded by constitutive ubiquitination in primary MPM cells derived from patients poorly responsive to cisplatin. LIP ubiquitination was directly correlated with cisplatin chemosensitivity and was associated with patients' survival after chemotherapy. Overexpression of LIP restored cisplatin's pro-apoptotic effect by activating CHOP/TRB3/caspase 3 axis and up-regulating calreticulin, that triggered MPM cell phagocytosis by dendritic cells and expanded autologous anti-tumor CD8⁺CD107⁺T-cytotoxic lymphocytes. Proteasome inhibitor carfilzomib and lysosome inhibitor chloroquine prevented LIP degradation. The triple combination of carfilzomib, chloroquine and cisplatin increased ER stress-triggered apoptosis and immunogenic cell death in patients' samples, and reduced tumor growth in cisplatin-resistant MPM preclinical models.

CONCLUSION

The loss of LIP mediates cisplatin resistance, rendering LIP a possible predictor of cisplatin response in MPM patients. The association of proteasome and lysosome inhibitors reverses cisplatin resistance by restoring LIP levels and may represent a new adjuvant strategy in MPM treatment.

How asbestos drives the tissue towards tumors: YAP activation, macrophage and mesothelial precursor recruitment, RNA editing, and somatic mutations

Chronic exposure to intraperitoneal asbestos triggered a marked response in the mesothelium well before tumor development. Macrophages, mesothelial precursor cells, cytokines, and growth factors accumulated in the peritoneal lavage. Transcriptome profiling revealed YAP/TAZ activation in inflamed mesothelium with further activation in tumors, paralleled by increased levels of cells with nuclear YAP/TAZ. Arg1 was one of the highest upregulated genes in inflamed tissue and tumor. Inflamed tissue showed increased levels of single-nucleotide variations, with an RNA-editing signature, which were even higher in the tumor samples. Subcutaneous injection of asbestos-treated, but tumor-free mice with syngeneic mesothelioma tumor cells resulted in a significantly higher incidence of tumor growth when compared to naïve mice supporting the role of the environment in tumor progression.

New horizons from immunotherapy in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive disease with a severe prognosis. Medical treatment for MPM unresectable patients is still unsatisfactory; therefore novel therapeutic approaches are urgently needed. Immunotherapy represents a promising treatment for MPM patients. Here, we'll discuss the most promising immunotherapeutic treatments currently under active investigation for this still dreadful disease.

Bromodomain inhibition exerts its therapeutic potential in malignant pleural mesothelioma by promoting immunogenic cell death and changing the tumor immune-environment

Systemic treatment of malignant pleural mesothelioma (MPM) is moderately active for the intrinsic pharmacological resistance of MPM cell and its ability to induce an immune suppressive environment. Here we showed that the expression of bromodomain (BRD) proteins BRD2, BRD4 and BRD9 was significantly higher in human primary MPM cells compared to normal mesothelial cells (HMC). Nanomolar concentrations of bromodomain inhibitors (BBIs) JQ1 or OTX015 impaired patient-derived MPM cell proliferation and induced cell-cycle arrest without affecting apoptosis. Importantly, BBIs primed MPM cells for immunogenic cell death, by increasing extracellular release of ATP and HMGB1, and by promoting membrane exposure of calreticulin and ERp57. Accordingly, BBIs activated dendritic cell (DC)-mediated phagocytosis and expansion of CD8⁺ T-lymphocyte clones endorsed with antitumor cytotoxic activity. BBIs reduced the expression of the immune checkpoint ligand PD-L1 in MPM cells; while both CD8⁺ and CD4⁺ T-lymphocytes co-cultured with JQ1-treated MPM cells decreased PD-1 expression, suggesting a disruption of the immune-suppressive PD-L1/PD-1 axis. Additionally, BBIs reduced the expansion of myeloid-derived suppressor cells (MDSC) induced by MPM cells. Finally, a preclinical model of MPM confirmed that the anti-tumor efficacy of JQ1 was largely due to its ability to restore an immune-active environment, by increasing intra-tumor DC and CD8⁺ T-lymphocytes, and decreasing MDSC. Thereby, we propose that, among novel drugs, BBIs should be investigated for MPM treatment for their combined activity on both tumor cells and surrounding immune-environment.

Review of cancer treatment with immune checkpoint inhibitors : Current concepts, expectations, limitations and pitfalls

Immunotherapy by checkpoint inhibition is about to profoundly change cancer therapy. The number of indications are growing at an unprecedented speed. Clinical studies have demonstrated efficacy in a variety of solid tumors and in hematologic malignancies, although some clinical trials have produced negative results. Thus, it is fair to assume that there are obvious limitations and pitfalls in immunotherapy. Future concepts for combination treatment of immune checkpoint inhibitors have to be developed, but there is also urgent need for better and standardized biomarkers to identify those cancer patients who will benefit from treatment by checkpoint inhibition. The current overview summarizes current knowledge on immune checkpoint inhibitor treatment in malignancies, its outlook and limitations, diagnostic means and, finally, side effect management.

Abundant expression of TIM-3, LAG-3, PD-1 and PD-L1 as immunotherapy checkpoint targets in effusions of mesothelioma patients

Malignant pleural mesothelioma (MPM) is an aggressive cancer with an increasing incidence, poor prognosis and limited effective treatment options. Hence, new treatment strategies are warranted which include immune checkpoint blockade approaches with encouraging preliminary data. Research on the immunological aspects of the easily accessible mesothelioma microenvironment could identify prognostic and/or predictive biomarkers and provide useful insights for developing effective immunotherapy. In this context, we investigated the immune cell composition of effusions (pleural and ascites fluids) from 11 different chemotherapy-treated MPM patients. We used multicolor flow cytometry to describe different subsets of immune cells and their expression of immune checkpoint molecules TIM-3, LAG-3, PD-1 and PD-L1. We demonstrate a patient-dependent inter- and intraspecific variation comparing pleural and ascites fluids in immune cell composition and immune checkpoint expression. We found CD4⁺ and CD8⁺ T cells, B cells, macrophages, natural killer cells, dendritic cells and tumor cells in the fluids. To the best of our knowledge, we are the first to report TIM-3 and LAG-3 expression and we confirm PD-1 and PD-L1 expression on different MPM effusion-resident immune cells. Moreover, we identified two MPM effusion-related factors with clinical value: CD4+ T cells were significantly correlated with better response to chemotherapy, while the percentage of PD-L1⁺ podoplanin (PDPN)⁺ tumor cells is a significant prognostic factor for worse outcome. Our data provide a basis for more elaborate research on MPM effusion material in the context of treatment follow-up and prognostic biomarkers and the development of immune checkpoint-targeted immunotherapy.

PD-L1 inhibitors in the pipeline: Promise and progress

Checkpoint inhibitors have improved survival for patients with melanoma, non-small-cell lung cancer (NSCLC), bladder, head and neck and other cancers. Antibodies against PD-L1, including atezolizumab, avelumab and durvalumab, are also being developed and have been approved for various cancers. Compared with anti-CTLA-4 drugs, studies with anti-PD-1/PD-L1 agents have suggested higher response rates and improved survival. Targeting PD-L1 rather than PD-1 may also theoretically offer further benefit, with the potential for improved efficacy and reduced toxicity, although this has not been clearly shown by clinical experience to date. Anti-PD-L1 agents have shown good efficacy and manageable toxicity in several tumor types.

Determination of PD-L1 expression in effusions from mesothelioma by immuno-cytochemical staining

BACKGROUND

Malignant mesothelioma (MM) is an aggressive, fatal tumor. Current therapeutic options only marginally improve survival. Programmed cell death ligand 1 (PD-L1) is a dominant mediator of immunosuppression, binding to programmed cell death 1 (PD-1). PD-L1 is up-regulated in cancer cells, and the PD-1/PD-L1 pathway plays a critical role in tumor immune evasion, thus providing a target for antitumor therapy. Further, a correlation between PD-L1 expression and prognosis has been reported. Studies performed on histological material have revealed expression of PD-L1 in MM, but no study has been performed on MM effusions thus far.

METHODS

PD-L1 expression was determined by a commercially available antibody (clone 28-8) in 74 formalin-fixed, paraffin-embedded cell blocks from body effusions obtained at diagnosis from patients with MM. The presence of MM cells was confirmed with CK5/6, calretinin, and EMA and the admixture of macrophages was assessed with CD68. Only cases containing more than 100 tumor cells were assessed. Membranous staining in tumor cells was considered positive. Survival time was calculated from the appearance of the first malignant effusion until death.

RESULTS

Reactivity was observed in 23 of 61 (38%) of cases and was classified as ≥1%-5% (n = 9 cases), >5%-10% (n = 4 cases), >10%-50% (n = 4 cases), and >50% (n = 6 cases) positive cells. Survival times did not differ significantly between patients with PD-L1-positive and PD-L1-negative tumors.

CONCLUSION

MM effusions are suitable for immune-cytochemical assessment of PD-L1 expression in malignant cells and the results are similar to those reported for histological specimens. Cancer Cytopathol 2017;125:908-17. © 2017 American Cancer Society.

Anti-CTLA-4 therapy for malignant mesothelioma

Immunotherapy is an emerging therapeutic strategy with a promising clinical outcome in some solid tumors, particularly metastatic melanoma. One approach to immunotherapy is immune checkpoint inhibitors, such as blockage of CTLA-4 and PD-1/PD-L1. This special report aims to describe the state of clinical trials of tremelimumab in patients with unresectable malignant mesothelioma (MM) in particular with regard to the clinical efficacy, safety and tolerability. Criticism and perspective of this treatment are also discussed. Biological and clinical considerations rule out the use of tremelimumab as single agent for MM and, more generally, the use of immune checkpoint inhibitors for MM is still largely questionable and not supported by evidences.

Immune checkpoint therapy of mesothelioma: Pre-clinical bases and clinical evidences

Treatment with immune-checkpoint blocking monoclonal antibody (mAb) is demonstrating a significant efficacy in different tumor types. Here, we discuss the impact of this promising approach in malignant mesothelioma (MM), a still dreadful disease in which medical treatment has been set on platinum based chemotherapy for decades with unsatisfactory results.

Novel systemic therapy against malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive tumor of the pleura with an overall poor prognosis. Even with surgical resection, for which only a subset of patients are eligible, long term disease free survival is rare. Standard first-line systemic treatment consists of a platinum analog, an anti-metabolite, and sometimes anti-angiogenic therapy, but there is currently no well-established standard therapy for refractory or relapsed disease. This review focuses on efforts to develop improved systemic therapy for the treatment of malignant pleural mesothelioma (MPM) including cytotoxic systemic therapy, a variety of tyrosine kinase inhibitors and their downstream effector pathways, pharmacologic targeting of the epigenome, novel approaches to target proteins expressed on mesothelioma cells (such as mesothelin), arginine depletion therapy, and the emerging role of immunotherapy. Overall, these studies demonstrate the challenges of improving systemic therapy for MPM and highlight the need to develop therapeutic strategies to control this disease.

ADCC employing an NK cell line (haNK) expressing the high affinity CD16 allele with avelumab, an anti-PD-L1 antibody

NK-92 cells, and their derivative, designated aNK, were obtained from a patient with non-Hodgkin lymphoma. Prior clinical studies employing adoptively transferred irradiated aNK cells have provided evidence of clinical benefit and an acceptable safety profile. aNK cells have now been engineered to express IL-2 and the high affinity (ha) CD16 allele (designated haNK). Avelumab is a human IgG1 anti-PD-L1 monoclonal antibody, which has shown evidence of clinical activity in a range of human tumors. Prior in vitro studies have shown that avelumab has the ability to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) of human tumor cells when combined with NK cells. In the studies reported here, the ability of avelumab to enhance the lysis of a range of human carcinoma cells by irradiated haNK cells via the ADCC mechanism is demonstrated; this ADCC is shown to be inhibited by anti-CD16 blocking antibody and by concanamycin A, indicating the use of the granzyme/perforin pathway in tumor cell lysis. Studies also show that while NK cells have the ability to lyse aNK or haNK cells, the addition of NK cells to irradiated haNK cells does not inhibit haNK-mediated lysis of human tumor cells, with or without the addition of avelumab. Avelumab-mediated lysis of tumor cells by irradiated haNK cells is also shown to be similar to that of NK cells bearing the V/V Fc receptor high affinity allele. These studies thus provide the rationale for the clinical evaluation of the combined use of avelumab with that of irradiated adoptively transferred haNK cells.

Immunohistochemical evaluation of two antibodies against PD-L1 and prognostic significance of PD-L1 expression in epithelioid peritoneal malignant mesothelioma: A RENAPE study

BACKGROUND

Epithelioid peritoneal malignant mesothelioma (EPMM) is the most common subtype of this aggressive tumor. We compared two antibodies against PD-L1, a recent theranostic biomarker, and evaluated the prognostic value of PD-L1 expression by mesothelial and immune cells in EPMM.

METHODS

Immunohistochemistry was performed on 45 EPMM. Clinical and pathological data were extracted from the RENAPE database. Using E1L3N and SP142 clones, inter-observer agreement, PD-L1 expression by mesothelial and immune cells and inter-antibody agreement were evaluated. The prognostic relevance of PD-L1 expression was evaluated in 39 EPMM by univariate and multivariate analysis of overall survival (OS) and progression-free survival (PFS).

RESULTS

Inter-observer agreement on E1L3N immunostaining was moderate for mesothelial and immune cells, and fair for mesothelial and poor for immune cells using SP142. Using E1L3N, 31.1% of mesothelial and 15.6% of immune cells expressed PD-L1, and 22.2% of mesothelial and 26.7% of immune cells using SP142. Inter-antibody agreement was moderate. In most positive cases, 1-5% of tumor cells were positive. Using E1L3N, PD-L1 expression by lymphocytes was associated with better OS and PFS by both univariate and multivariate analysis. Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy predicted better prognosis than other treatments. Solid subtype was an independent prognostic factor for worse OS.

CONCLUSION

E1L3N appeared easier to use than SP142 to evaluate PD-L1 expression. A minority of EPMM expressed PD-L1, and only a few cells were positive. PD-L1 expression by immune cells evaluated with E1L3N was an independent prognostic factor in EPMM.

Avelumab for metastatic or locally advanced previously treated solid tumours (JAVELIN Solid Tumor): a phase 1a, multicohort, dose-escalation trial

BACKGROUND

Avelumab (MSB0010718C) is a human IgG1 monoclonal antibody that binds to PD-L1, inhibiting its binding to PD-1, which inactivates T cells. We aimed to establish the safety and pharmacokinetics of avelumab in patients with solid tumours while assessing biological correlatives for future development.

METHODS

This open-label, single-centre, phase 1a, dose-escalation trial (part of the JAVELIN Solid Tumor trial) assessed four doses of avelumab (1 mg/kg, 3 mg/kg, 10 mg/kg, and 20 mg/kg), with dose-level cohort expansions to provide additional safety, pharmacokinetics, and target occupancy data. This study used a standard 3 + 3 cohort design and assigned patients sequentially at trial entry according to the 3 + 3 dose-escalation algorithm and depending on the number of dose-limiting toxicities during the first 3-week assessment period (the primary endpoint). Patient eligibility criteria included age 18 years or older, Eastern Cooperative Oncology Group performance status 0-1, metastatic or locally advanced previously treated solid tumours, and adequate end-organ function. Avelumab was given as a 1-h intravenous infusion every 2 weeks. Patients in the dose-limiting toxicity analysis set were assessed for the primary endpoint of dose-limiting toxicity, and all patients enrolled in the dose-escalation part were assessed for the secondary endpoints of safety (treatment-emergent and treatment-related adverse events according to National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0), pharmacokinetic and pharmacodynamic profiles (immunological effects), best overall response by Response Evaluation Criteria, and antidrug antibody formation. The population for the pharmacokinetic analysis included a subset of patients with rich pharmacokinetic samples from two selected disease-specific expansion cohorts at the same study site who had serum samples obtained at multiple early timepoints. This trial is registered with ClinicalTrials.gov, number NCT01772004. Patient recruitment to the dose-escalation part reported here is closed.

FINDINGS

Between Jan 31, 2013, and Oct 8, 2014, 53 patients were enrolled (four patients at 1 mg/kg, 13 at 3 mg/kg, 15 at 10 mg/kg, and 21 at 20 mg/kg). 18 patients were analysed in the dose-limiting toxicity analysis set: three at dose level 1 (1 mg/kg), three at dose level 2 (3 mg/kg), six at dose level 3 (10 mg/kg), and six at dose level 4 (20 mg/kg). Only one dose-limiting toxicity occurred, at the 20 mg/kg dose, and thus the maximum tolerated dose was not reached. In all 53 enrolled patients (the safety analysis set), common treatment-related adverse events (occurring in >10% of patients) included fatigue (21 patients [40%]), influenza-like symptoms (11 [21%]), fever (8 [15%]), and chills (6 [11%]). Grade 3-4 treatment-related adverse events occurred in nine (17%) of 53 patients, with autoimmune disorder (n=3), increased blood creatine phosphokinase (n=2), and increased aspartate aminotransferase (n=2) each occurring in more than one patient (autoimmune disorder in two patients at 10 mg/kg and one patient at 20 mg/kg, increased blood creatine phosphokinase in two patients at 20 mg/kg, and increased aspartate aminotransferase in one patient at 1 mg/kg, and one patient at 10 mg/kg). Six (11%) of 53 patients had a serious treatment-related adverse event: autoimmune disorder (two [13%]), lower abdominal pain (one [7%]), fatigue (one [7%]), and influenza-like illness (one [7%]) in three patients treated at 10 mg/kg dose level, and autoimmune disorder (one [5%]), increased amylase (one [5%]), myositis (one [5%]), and dysphonia (one [5%]) in three patients who received the 20 mg/kg dose. We recorded some evidence of clinical activity in various solid tumours, with partial confirmed or unconfirmed responses in four (8%) of 53 patients; 30 (57%) additional patients had stable disease. Pharmacokinetic analysis (n=86) showed a dose-proportional exposure between doses of 3 mg/kg and 20 mg/kg and a half-life of 95-99 h (3·9-4·1 days) at the 10 mg/kg and 20 mg/kg doses. Target occupancy was greater than 90% at doses of 3 mg/kg and 10 mg/kg. Antidrug antibodies were detected in two (4%) of 53 patients. No substantial differences were found in absolute lymphocyte count or multiple immune cell subsets, including those expressing PD-L1, after treatment with avelumab. 31 (58%) of 53 patients in the overall safety population died; no deaths were related to treatment on study.

INTERPRETATION

Avelumab has an acceptable toxicity profile up to 20 mg/kg and the maximum tolerated dose was not reached. Based on pharmacokinetics, target occupancy, and immunological analysis, we chose 10 mg/kg every 2 weeks as the dose for further development and phase 3 trials are ongoing.

FUNDING

National Cancer Institute and Merck KGaA.

Avelumab: combining immune checkpoint inhibition and antibody-dependent cytotoxicity

INTRODUCTION

Immune checkpoint inhibition holds great promise for selected tumors. The human monoclonal antibody (mAB) avelumab is directed to programmed death ligand-1 (PD-L1) and is supposed to inhibit the immunosuppressive PD-L1/PD-1 interaction and, furthermore, effect antibody-dependent cytotoxicity (ADCC) lysis of tumor cells. Areas covered: This article presents an overview of the current means to activate the antitumor immune defense by targeting PD-1 or PD-L1 with mABs and their possible role in ADCC-mediated tumor cell elimination. Expert opinion: Avelumab contains a Fc region which can bind cognate receptors on immune effector cells and induce ADCC-mediated tumor cell lysis, in contrast to other mABs directed to PD-1/PD-L1 which lack the ability to trigger ADCC due to belonging to the IgG4 subclass or possessing a mutated Fc region. Preclinical and clinical data indicate that avelumab can be safely administered to cancer patients with a toxicity profile comparable to other mABs and without lysis of PD-L1-positive activated immune cells. This antibody yielded durable responses in a phase II trial in advanced Merkel cell carcinoma patients. Tumor cell lysis by avelumab prevents cells from resorting to alternative checkpoints as shown by targeting PD-1 and the upregulation of TIM-3.

Analyses of the peripheral immunome following multiple administrations of avelumab, a human IgG1 anti-PD-L1 monoclonal antibody

Background

Multiple anti-PD-L1/PD-1 checkpoint monoclonal antibodies (MAb) have shown clear evidence of clinical benefit. All except one have been designed or engineered to omit the possibility to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) as a second potential mode of anti-tumor activity; the reason for this is the concern of lysis of PD-L1 positive immune cells. Avelumab is a fully human IgG1 MAb which has been shown in prior in vitro studies to mediate ADCC versus a range of human tumor cells, and clinical studies have demonstrated anti-tumor activity versus a range of human cancers. This study was designed to investigate the effect on immune cell subsets in the peripheral blood of cancer patients prior to and following multiple administrations of avelumab.

Methods

One hundred twenty-three distinct immune cell subsets in the peripheral blood of cancer patients (n = 28) in a phase I trial were analyzed by flow cytometry prior to and following one, three, and nine cycles of avelumab. Changes in soluble (s) CD27 and sCD40L in plasma were also evaluated. In vitro studies were also performed to determine if avelumab would mediate ADCC of PBMC.

Results

No statistically significant changes in any of the 123 immune cell subsets analyzed were observed at any dose level, or number of doses, of avelumab. Increases in the ratio of sCD27:sCD40L were observed, suggesting potential immune activation. Controlled in vitro studies also showed lysis of tumor cells by avelumab versus no lysis of PBMC from five donors.

Conclusions

These studies demonstrate the lack of any significant effect on multiple immune cell subsets, even those expressing PD-L1, following multiple cycles of avelumab. These results complement prior studies showing anti-tumor effects of avelumab and comparable levels of adverse events with avelumab versus other anti-PD-1/PD-L1 MAbs. These studies provide the rationale to further exploit the potential ADCC mechanism of action of avelumab as well as other human IgG1 checkpoint inhibitors.

Trial registration

ClinicalTrials.gov identifier: NCT01772004 (first received: 1/14/13; start date: January 2013) and NCT00001846 (first received date: 11/3/99; start date: August 1999).

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0220-y) contains supplementary material, which is available to authorized users.