Emily Pulford

Fibulin-3 levels in malignant pleural mesothelioma are associated with prognosis but not diagnosis.

Background:Fibulin-3 (FBLN3) was recently presented as a promising novel biomarker for malignant pleural mesothelioma (MPM), warranting independent validation studies.Methods:ELISA was used to measure cellular and secreted FBLN3 in cell lines, in plasma of xenograft tumour-bearing mice, in plasma from two independent series of MPM and non-MPM patients and in pleural fluid from a third series. Diagnostic and prognostic potential of FBLN3 was assessed by receiver operating characteristics curve analysis and Kaplan–Meier method, respectively.Results:FBLN3 was expressed in all MPM and benign mesothelial cell lines tested, and a correlation was observed between cellular protein expression and secreted levels. Human FBLN3 was detectable in plasma of tumour-bearing mice, suggesting that MPM cells contribute to levels of circulating FBLN3. Plasma FBLN3 was significantly elevated in MPM patients from the Sydney cohort, but not the Vienna cohort, but the diagnostic accuracy was low (63%, (95% CI: 50.1–76.4) and 56% (95% CI: 41.5–71.0), respectively). Although FBLN3 levels in pleural effusions were not significantly different between cases and controls, FBLN3 levels in pleural effusion fluid were found to be independently associated with prognosis (hazard ratio of 9.92 (95% CI: 2.14–45.93)).Conclusions:These data confirm the potential prognostic value of pleural effusion FBLN3, but question the diagnostic value of this protein in MPM patients.

Usefulness of Aquaporin 1 as a Prognostic Marker in a Prospective Cohort of Malignant Mesotheliomas

(1) Background: Malignant mesothelioma (MM) is an aggressive tumour of the serosal membranes, associated with exposure to asbestos. Survival is generally poor, but prognostication for individual patients is difficult. We recently described Aquaporin 1 (AQP1) as independent prognostic factor in two separate retrospective cohorts of MM patients. Here we assess the usefulness of AQP1 prospectively, and determine the inter-observer agreement in assessing AQP1 scores; (2) Methods: A total of 104 consecutive cases of MM were included. Sufficient tissue for immunohistochemistry was available for 100 cases, and these cases were labelled for AQP1. Labelling was assessed by two pathologists. Complete clinical information and follow up was available for 91 cases; (3) Results: Labelling of ≥50% of tumour cells for AQP indicated improved prognosis in a univariate model (median survival 13 versus 8 months, p = 0.008), but the significance was decreased in a multivariate analysis. Scoring for AQP1 was robust, with an inter-observer kappa value of 0.722, indicating substantial agreement between observers; (4) Conclusion: AQP1 is a useful prognostic marker that can be easily incorporated in existing diagnostic immunohistochemical panels and which can be reliably interpreted by different pathologists.

The Effect of Aquaporin 1-Inhibition on Vasculogenic Mimicry in Malignant Mesothelioma

Malignant mesothelioma (MM) is an aggressive malignancy of the serosal membranes, with poor overall survival and quality of life. Limited targeted treatment strategies exist due to restricted knowledge of pathogenic pathways. Vasculogenic mimicry (VM) is a newly described phenomenon associated with increased aggressiveness in other malignancies, and has been characterized in MM. Normal mesothelium expresses aquaporin 1 (AQP1) and retained expression has been associated with improved survival in MM. AQP1 is expressed by normal vascular endothelium and is involved in mediating MM cell motility and proliferation. We investigated the role of AQP1 in VM, and its interaction with the pro-angiogenic factor vascular endothelial growth factor A (VEGFA), which is variably expressed in MM. Matrigel VM assays were performed using NCI-H226 and NCI-H28 MM cell lines and primary cells in hypoxia and normoxia. The synthetic blocker AqB050 and siRNA were used to inhibit AQP1, and bevacizumab was used to inhibit VEGF. Inhibition of AQP1 resulted in increased VEGFA secretion by MM cells and reduced VM in MM cell lines in hypoxia but not normoxia. No change in VM was seen in MM primary cells. Combined inhibition of AQP1 and VEGF had no effect on VM in normoxia. In a heterotopic xenograft mouse model, AqB050 treatment did not alter vessel formation. AQP1 may interact with VEGFA and play a role in VM, especially under hypoxic conditions, but the heterogeneity of MM cells may result in different dominant pathways between patients.

Malignant Mesothelioma, BAP1 Immunohistochemistry, and VEGFA: Does BAP1 Have Potential for Early Diagnosis and Assessment of Prognosis?

Malignant mesothelioma (MM) is an aggressive malignancy of the serosal membranes. Early diagnosis and accurate prognostication remain problematic. BAP1 is a tumour suppressor gene commonly mutated in MM. Germline BAP1 mutation has been associated with early onset and less aggressive disease compared with sporadic MM. Sporadic BAP1 mutations are common and are associated with improved survival in MM, contrary to other malignancies. This study investigated the prognostic role of BAP1 in matched cytology and surgical specimens and aimed to investigate the association between BAP1 and the established prognostic marker VEGFA from a cohort of 81 patients. BAP1 mutation was found in 58% of histology and 59% of cytology specimens. Loss of BAP1 expression in both surgical and cytology specimens was significantly associated with poorer survival in a multivariate analysis when controlling for known prognostic indicators. Increased levels of VEGFA in pleural effusions were associated with poor survival. We conclude that the prognostic significance of BAP1 mutations in MM cannot be determined in isolation of other prognostic factors, which may vary between patients. Pathologists should employ caution when commenting on prognostic implications of BAP1 status of MM patients in diagnostic pathology reports, but it may be useful for early diagnosis.

Pleural malignant mesothelioma versus pleuropulmonary synovial sarcoma: a clinicopathological study of 22 cases with molecular analysis and survival data

The aim of this study was to carry out a comparative analysis by transducin-like enhancer of split 1 (TLE1) immunohistochemistry and molecular analysis of SYT-SSX, for 16 pleural predominantly sarcomatoid mesotheliomas and six cases of pleuropulmonary synovial sarcoma (five pleural in distribution only, with one case of a predominantly subpleural upper lobe synovial sarcoma), all of which were solely or predominantly monophasic. Our comparison included survival and some clinical data. We consider that the following points emerged from this study.

Quantitative mass spectrometry to identify protein markers for diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a devastating malignancy with a prognosis of <12 months. Even with bans on the use of asbestos in most Western countries, the incidence is still increasing due to the long latency periods between exposure and development of the disease. Diagnosis is often delayed due to invasive biopsies and lack of distinguishable markers. Patients frequently present with pleural effusions months to years before a radiologically detectable mass appears. This study aimed to investigate the proteome of pleural effusions taken from patients with MPM, adenocarcinoma and benign conditions in an attempt to identify a biomarker for early diagnosis. We identified several proteins that may be possible targets and warrant further investigation. Due to the predominance of up regulated proteins involved in VEGF signalling in MPM, we analysed VEGFA levels in effusions and found a strong correlation between VEGFA levels and survival in MPM.

CorrespondenceVasculogenic mimicry in vitro in tumour cells derived from metastatic malignant pleural effusions

© 2017 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved. This author accepted manuscript is made available following 12 month embargo from date of publication (July 2017) in accordance with the publisher’s archiving policy

Vasculogenic mimicry in vitro in tumour cells derived from metastatic malignant pleural effusions [Letter to the editor]

© 2017 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved. This author accepted manuscript is made available following 12 month embargo from date of publication (July 2017) in accordance with the publisher’s archiving policy

Vasculogenic mimicry in vitro in tumour cells derived from metastatic malignant pleural effusions

© 2017 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved. This author accepted manuscript is made available following 12 month embargo from date of publication (July 2017) in accordance with the publisher’s archiving policy