Retrospective evaluation of the use of pembrolizumab in malignant mesothelioma in a real-world Australian population

Introduction: We investigated the efficacy and toxicity of pembrolizumab in patients with mesothelioma from a real-world Australian population. We aimed to determine clinical factors and predictive biomarkers that could help select patients who are likely to benefit from pembrolizumab. Method: Patients with mesothelioma who were treated with pembrolizumab as part of the Insurance and Care New South Wales compensation scheme were included. Clinical information was collected retrospectively. Tumor biomarkers such as programmed death-ligand 1 (PD-L1), BAP1, and CD3-positive (CD3+) tumor-infiltrating lymphocytes (TILs) were examined using archival formalin-fixed paraffin-embedded tumor samples. Results: A total of 98 patients were included with a median age of 70 years (range, 46–91 y); 92% were men; 76% had epithelioid subtype; 21% had an Eastern Cooperative Oncology Group (ECOG) performance status of 0. Pembrolizumab was used as second-line or subsequent-line treatment in 94 patients and as first-line treatment in four patients. The overall response rate was 18%, and the disease control rate was 56%. The median progression-free survival (PFS) was 4.8 months (95% confidence interval: 3.6–6.2), and the median overall survival (OS) was 9.5 months (95% confidence interval: 6.6–13.7). Immune-related adverse events occurred in 27% of patients, of which nine (9%) were of grade 3 or higher. In the multivariable analysis, factors independently associated with longer PFS included baseline ECOG status of 0 (median PFS: 12 mo versus 4 mo, p < 0.01) and PD-L1 tumor proportion score of greater than or equal to 1% (median PFS: 6 mo versus 4 mo, p < 0.01). Baseline platelet count of less than or equal to 400 × 109/liter was independently associated with longer PFS and OS (median PFS: 6 mo versus 2 mo, p = 0.05; median OS: 10 mo versus 4 mo, p = 0.01), whereas lack of pretreatment dexamethasone was independently associated with OS but not PFS (median OS: 10 mo versus 3 mo, p = 0.01). The odds of response were higher for patients with baseline ECOG status of 0 (p = 0.02) and with greater than or equal to 5% CD3+ TILs in the tumor (p < 0.01). PD-L1 expression, BAP1 loss, and CD3+ TILs in the stroma were not significantly associated with the overall response rate. Conclusions: Immunotherapy is a reasonable treatment option for patients with mesothelioma. Our results are comparable to other clinical trials investigating pembrolizumab in mesothelioma in terms of response. Good performance status assessment remains the most robust predictor for patient outcomes. CD3+ TILs in the tumor may help select patients that are likely to respond to pembrolizumab, whereas factors such as PD-L1 expression, baseline platelet count, and lack of pretreatment dexamethasone may help predict survival outcomes from pembrolizumab treatment

Discovery of biomarkers in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer that occurs in the pleura, a thin membrane that lines the lungs and the chest cavity. It is associated with exposure to asbestos. MPM is considered a rare cancer; however, it has one of the poorest survival rates of any cancer in the world, with the median survival ranging from a few months to a couple of years. There is currently an urgent clinical need for biomarkers that can help with early diagnosis, improve prognostication, and help develop targeted therapies for MPM. In the first study, the expression of BIN1, IDO1 and PD-L1, and the presence of T-cells (CD3+), B-cells (CD20+) and macrophages (CD68+), was evaluated by immunohistochemistry in tumour samples from 67 patients who underwent surgical resection between 1992 and 2007. IDO1 was positive for 20 patients (30%) and BIN1 expression was high for 35 patients (50%). Survival analyses revealed that high BIN1 expression was associated with better overall survival (median: 12 vs 6 months for high and low BIN1 respectively, p=0.03). However, neither IDO1 expression, nor the numbers of lymphocytes and macrophages were significantly associated with overall survival. Multivariate analysis showed BIN1 remained an independent prognostic indicator (HR 0.44; 95% CI: 0.23-0.83, p=0.01). There was a significant correlation between PD-L1 and CD3 in stroma cells (p=0.02), CD3+ in tumour cells (p=0.01) and CD68+ in tumour cells (p=0.004). This study is the first to demonstrate that high BIN1 expression is a favourable prognostic biomarker in MPM. In the second study, the efficacy and toxicity of pembrolizumab, an anti-PD-1 checkpoint inhibitor antibody, was evaluated in a real-world Australian population. Clinical information was collected retrospectively and tumour biomarkers including PD-L1, BAP1 and tumour infiltrating lymphocytes (TILs; CD3+) were examined for their predictive potential using archival formalin-fixed paraffin-embedded tissues. Several clinical factors were also analysed for their potential to predict outcomes from pembrolizumab. The study demonstrated that single agent pembrolizumab is well tolerated by patients and is effective in a small proportion of patients, with an overall response rate of 18%. Traditional performance status assessment was the most robust predictor for patient outcome, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 associated with better overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Clinical factors that predicted for longer survival included the lack of corticosteroids pre-treatment, non-elevated absolute platelet count, onset of immune-related adverse events and PD-L1 expression. TILs in the tumour were significantly associated with overall response rate, suggesting it may help select patients who are likely to respond to pembrolizumab. BAP1 loss was not significantly associated with any efficacy outcomes. Our study included 98 patients, representing the largest retrospective study of outcomes in patients receiving pembrolizumab outside of a clinical trial to date. The final study involved laboratory research to investigate the role of tumour-derived extracellular vesicles (EV) as potential biomarkers in MPM. EV are 30-1000 nm membranous particles secreted by all cells (including cancerous cells) and carry various cargo containing proteins, lipids, and genetic materials from one cell to another. The availability and accessibility of EV in all body fluids make them a great candidate for liquid biopsies. EV was isolated from five MPM cell lines, an immortalized mesothelial cell line, and patient plasma samples. Three main subtypes of EV (exosomes, microvesicles and large oncosomes) were characterised using nanoparticle tracking analysis, flow cytometry, western blotting, transmission electron microscopy and proteomics. Major differences were found in the cargo between the different EV subtypes in all MPM cell lines. This study demonstrated, for the first time, the presence of PD-L1 and mesothelin in distinct subtypes of EV, opening a novel pathway to non-invasive or minimally invasive biopsies for the identification of biomarkers in MPM. In summary, this discovery project has identified multiple candidate biomarkers for MPM and laid the foundation for the development of future novel therapeutic targets that may significantly improve the clinical management of MPM

An update on predictive biomarkers for treatment selection in non-small cell lung cancer

It is now widely established that management of lung cancer is much more complex and cannot be centered on the binary classification of small-cell versus non-small cell lung cancer (NSCLC). Lung cancer is now recognized as a highly heterogeneous disease that develops from genetic mutations and gene expression patterns, which initiate uncontrolled cellular growth, proliferation and progression, as well as immune evasion. Accurate biomarker assessment to determine the mutational status of driver mutations such as EGFR, ALK and ROS1, which can be targeted by specific tyrosine kinase inhibitors, is now essential for treatment decision making in advanced stage NSCLC and has shifted the treatment paradigm of NSCLC to more individualized therapy. Rapid advancements in immunotherapeutic approaches to NSCLC treatment have been paralleled by development of a range of potential predictive biomarkers that can enrich for patient response, including PD-L1 expression and tumor mutational burden. Here, we review the key biomarkers that help predict response to treatment options in NSCLC patients

Small and Large Extracellular Vesicles Derived from Pleural Mesothelioma Cell Lines Offer Biomarker Potential

Pleural mesothelioma, previously known as malignant pleural mesothelioma, is an aggressive and fatal cancer of the pleura, with one of the poorest survival rates. Pleural mesothelioma is in urgent clinical need for biomarkers to aid early diagnosis, improve prognostication, and stratify patients for treatment. Extracellular vesicles (EVs) have great potential as biomarkers; however, there are limited studies to date on their role in pleural mesothelioma. We conducted a comprehensive proteomic analysis on different EV populations derived from five pleural mesothelioma cell lines and an immortalized control cell line. We characterized three subtypes of EVs (10 K, 18 K, and 100 K), and identified a total of 4054 unique proteins. Major differences were found in the cargo between the three EV subtypes. We show that 10 K EVs were enriched in mitochondrial components and metabolic processes, while 18 K and 100 K EVs were enriched in endoplasmic reticulum stress. We found 46 new cancer-associated proteins for pleural mesothelioma, and the presence of mesothelin and PD-L1/PD-L2 enriched in 100 K and 10 K EV, respectively. We demonstrate that different EV populations derived from pleural mesothelioma cells have unique cancer-specific proteomes and carry oncogenic cargo, which could offer a novel means to extract biomarkers of interest for pleural mesothelioma from liquid biopsies

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