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

Our plain-English summary of Abundant expression of TIM-3, LAG-3, PD-1 and PD-L1 as immunotherapy checkpoint targets in effusions of mesothelioma patients, by E. Marcq, J. Waele, J.V. Audenaerde, et al (Oncotarget, 2017).

The study

• Authors: E. Marcq, J. Waele, J.V. Audenaerde, E. Lion, E. Santermans, N. Hens, P. Pauwels, J.P. van Meerbeeck, E.L.J. Smits
• Journal: Oncotarget
• Published: 2017;8(52):89722-89735
• Cited by: 49 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

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.

In plain English

This laboratory study from Antwerp, Belgium, examined fluid samples from 11 patients with malignant pleural mesothelioma (MPM) who had received first-line chemotherapy (cisplatin plus pemetrexed) at least one month earlier. There were six samples of fluid from around the lungs (pleural fluid) and five of abdominal fluid (ascites). Using flow cytometry, the authors counted immune cell types and measured the immune checkpoint molecules TIM-3, LAG-3, PD-1 and PD-L1. All cell types studied were found, in proportions that varied between patients. Differences between pleural and ascites fluids were not statistically significant. TIM-3 was found on CD4+ T cells and natural killer cells in all 11 samples. PD-L1 was highest on tumor cells. Patients with higher percentages of CD4+ T cells more often responded to chemotherapy (odds ratio 1.13). Each 1% increase in PD-L1-positive tumor cells was linked to a 1.10-fold higher risk of dying (p = 0.011). The authors concluded that TIM-3 and LAG-3 are potential new treatment targets, and they named the small sample size as a limitation. Occupational asbestos exposure was recorded for 8 of the 11 patients, with no data for 3. Fiber types were not reported.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (flow cytometry) analysis of stored fluid samples from a small group of patients, with statistical comparison to chemotherapy response and survival
• Who was studied: 11 MPM patients whose samples came from Biobank@UZA in Antwerp, Belgium: 6 pleural fluid samples and 5 ascites samples. All had received first-line cisplatin plus pemetrexed at least one month before sample collection. Matched tissue samples were available for 4 patients. Collection dates are not given.
• Exposure: The study did not examine asbestos as an exposure. Its patient characteristics table records professional asbestos exposure as yes for 5 of the 6 pleural-fluid patients and 3 of the 5 ascites patients, with no data for the rest. Fiber types are not reported. All patients had prior cisplatin plus pemetrexed chemotherapy.
• Main results:
  • All cell types analysed were found, in variable proportions. The most common were CD4+ T cells, macrophages and dendritic cells, at up to 51.7%, 38.8% and 43.4% of viable cells respectively.
  • Ascites samples had higher percentages of immune cells than pleural fluid samples, but none of these differences was statistically significant (p-values 0.247 to 0.930).
  • TIM-3 was found on CD4+ T cells and natural killer cells in all 11 samples, and on CD8+ T cells in nine samples.
  • PD-L1 expression was highest on podoplanin-positive (PDPN+) tumor cells in both fluid types. The median was 19.4% PD-L1-positive cells.
  • In univariate analysis, patients with higher percentages of CD4+ T cells in their fluid more often had a partial or complete response to cisplatin/pemetrexed chemotherapy (odds ratio 1.13; pseudo R = 0.63, p = 0.033). Multivariate analysis was not feasible.
  • PD-L1 on tumor cells in the fluid was associated with survival: each 1% increase in PD-L1+ PDPN+ tumor cells increased the risk of dying by a factor of 1.10 (risk ratio 1.10, p = 0.011). No confidence interval is given.
  • In 4 patients with matched tissue and fluid samples, immune cell make-up and checkpoint expression differed between tissue and fluid. Tissue had higher percentages of macrophages and lymphocytes.
• The authors' conclusion: The authors concluded that PD-1, PD-L1, TIM-3 and LAG-3 are expressed in most effusion samples, which identifies TIM-3 and LAG-3 as potential new targets in MPM. They also concluded that CD4+ T cell percentage was correlated with chemotherapy response and PD-L1+ PDPN+ tumor cell percentage was a prognostic factor for worse outcome.
• Limitations the authors state:
  • Small sample size, which is why non-parametric tests were used.
  • Small sample size and discrete variables made multivariate analysis of chemotherapy response not feasible.
  • The fluid samples may not reflect the tumor microenvironment, because effusions often occur in an inflammatory context.
  • The authors say more evidence is needed that immune make-up depends on the patient rather than on the fluid type.

Topics

Medical terms in this study, explained in our Lexicon: PD-L1, Immunotherapy, Mesothelioma, Pleural Mesothelioma, Prognosis, Biomarker, Ascites, Chemotherapy.

Related studies

• Building a Bridge between Chemotherapy and Immunotherapy in Malignant Pleural Mesothelioma: Investigating the Effect of Chemotherapy on Immune Checkpoint Expression — E. Marcq, J.R.V. Audenaerde, et al. (2019)
• Tumour cell PD-L1 expression is prognostic in patients with malignant pleural effusion: the impact of C-reactive protein and immune-checkpoint inhibition — B. Ghanim, A. Rosenmayr, et al. (2020)
• LAG3 is an independent prognostic biomarker and potential target for immune checkpoint inhibitors in malignant pleural mesothelioma: a retrospective study — K. Arimura, K. Hiroshima, et al. (2023)
• CD276 as a critical independent biomarker and immune checkpoint inhibitor target in epithelioid mesothelioma-TCGA study — Y. Aoki, K. Arimura, et al. (2025)
• Immunotherapy with immune checkpoint inhibitors and predictive biomarkers in malignant mesothelioma: Work still in progress — M. Perrino, F. De Vincenzo, et al. (2023)
• PD-1/PD-L1 Checkpoint Inhibitor Immunotherapy for Malignant Pleural Mesothelioma: Case Series and Literature Review — M. Zhou, N. Joshi, et al. (2021)

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