Progress in the Management of Malignant Pleural Mesothelioma in 2017

Peritoneal mesothelioma (PM) is a rare and aggressive primary peritoneal malignancy characterized by widespread multiple metastatic tumour nodules originating from the peritoneum. The conventional classification distinguishes diffuse malignant peritoneal mesothelioma (DMPM) and border-line forms: multicystic peritoneal mesothelioma (MCPM) and well-differentiated papillary peritoneal mesothelioma (WDPPM). Despite the novel achievements in the management of PM, there is difficulty in conducting randomized trials due to its rarity and aggressive biology in many cases. As there is, a necessity to standardize diagnosis and management of PM, the Peritoneal Surface Oncology Group International (PSOGI) commissioned a steering committee to elaborate clinical guidelines.

Peritoneal mesothelioma: PSOGI/EURACAN clinical practice guidelines for diagnosis, treatment and follow-up.

Tumor PD-L1 expression in malignant pleural and peritoneal mesothelioma by Dako PD-L1 22C3 pharmDx and Dako PD-L1 28-8 pharmDx assays.

The tumor immune microenvironment (TME) and immune checkpoints have been reported to serve a role in the pathogenesis of malignant mesothelioma (MM) and treatment outcome. Additionally, mismatch Repair (MMR) deficiency appears to enhance the response to checkpoints blockade in several tumors. The aim of the present study was to analyze programmed death‑1 ligand 1 (PD‑L1) expression in MM and to characterize the TME. This could help to understand the immune response, and evaluate its prognostic and predictive values. We also investigated MMR protein expression. We retrospectively analyzed 55 mesotheliomas to determine PD‑L1, CD4+, CD8+, mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), mutS homolog 6 (MSH6) and PMS1 homolog 2, mismatch repair system component (PMS2) expression. We used an immunoscore (1+, 2+ and 3+) to evaluate tumor‑infiltrating lymphocytes (TILs). TILs were observed in all but two samples (53/55); the majority had an immunoscore 1+ (30/53), while 2+/3+ was reported for 23/53 samples. A predominance of CD8+ was highlighted in 8 cases (15%). PD‑L1 expression of ≥1% on tumor cells was displayed in 40 cases; in 9 of these, ≥50% expression was reported. Of note, alterations in MMR staining was not observed. In addition, survival analysis revealed that epithelioid subtype was associated with better prognosis. We observed a trend towards poorer prognosis for ≥50% PD‑L1 expression on tumor cells, lower immunoscore (1+) and CD8+ TIL predominance. The present study highlighted the importance of exploring the TME and the standardization of PD‑L1 assessment guidelines to apply in the field of immunotherapy.

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Role of evaluating tumor‑infiltrating lymphocytes, programmed death‑1 ligand 1 and mismatch repair proteins expression in malignant mesothelioma.

Background:The prognostic value of programmed death-ligand 1 (PD-L1) expression in patients with malignant pleural mesothelioma (MPM) has been controversial according to previous investigations. Th...

https://journals.sagepub.com/doi/pdf/10.1177/1758835920962362

PD-L1 and prognosis in patients with malignant pleural mesothelioma: a meta-analysis and bioinformatics 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.

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

H. Senellart

Papers

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