Reprogramming the tumor microenvironment in mesothelioma: from immune suppression to therapeutic opportunity

Our plain-English summary of Reprogramming the tumor microenvironment in mesothelioma: from immune suppression to therapeutic opportunity, by L. Cerbone, A. Garau, A. Balossino, et al (Frontiers in Immunology, 2026).

The study

• Authors: L. Cerbone, A. Garau, A. Balossino, S. Martinotti, E. Ranzato, C. Genova, V. Rigo, S. Meda, S. Ravera, H.J.S. Parra, M.C. Piccirillo, A. Gurrera, A. Terminella, M. Manitto, M. Croce, S. Coco, F. Grosso
• Journal: Frontiers in Immunology
• Published: 2026;17:1814514
• Type of article: Review
• Read it: PubMed · Publisher · Free full text

Abstract

Pleural mesothelioma (PM) is a rare and aggressive cancer with limited treatment options and poor prognosis. Unlike other thoracic cancers responding well to immunotherapy, PM typically lacks key predictive biomarkers such as Programmed Death-Ligand 1 (PD-L1) tumor expression. Nonetheless, immune checkpoint inhibitors (ICIs) have shown clinical activity in PM, particularly in non-epithelioid subtypes. However, only a subset of patients benefits from this approach, and resistance remains a major challenge. A growing body of evidence suggests that tumor microenvironment (TME) plays a central role in shaping this resistance. In PM, the TME is notably immunosuppressive, dominated by regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. These elements act as a shield against immune activation, limiting the efficacy of ICIs. Novel therapeutic strategies aimed at depleting or modulating suppressive immune populations within the TME are emerging as promising avenues to overcome resistance and enhance the effectiveness of ICIs. In this narrative review, we examine the unique features of the TME in PM, its role in immunotherapy resistance, and emerging strategies aimed at harnessing or remodeling the TME to improve patient outcomes.

Copyright © 2026 Cerbone, Garau, Balossino, Martinotti, Ranzato, Genova, Rigo, Meda, Ravera, Parra, Piccirillo, Gurrera, Terminella, Manitto, Croce, Coco and Grosso.

In plain English

This article was a narrative review of published research on the tumor microenvironment, meaning the immune and supporting cells around the tumor, in pleural mesothelioma. It did not study new patients. The authors described asbestos exposure as setting off the inflammation in which the disease begins. They described the mesothelioma microenvironment as generally immune-suppressed, or "cold", and said it differs between epithelioid and non-epithelioid tumors. Summarizing two earlier trials of immune checkpoint inhibitor drugs, the review reported that patients with non-epithelioid tumors gained the most benefit, while most patients did not benefit. It reported that PD-L1 testing alone was insufficient to predict who responds, and that tumor mutational burden had not shown significant predictive value. The review also surveyed trials of drugs that block blood-vessel growth, cell-based treatments and newer checkpoint drugs. The authors concluded that the microenvironment plays a major role in the disease, and called for large prospective multi-institutional studies. They noted that most immune signatures come from retrospective or mixed datasets, and that small sample sizes limit the evidence.

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: Narrative review of published laboratory, animal and clinical research
• Who was studied: No new patients were studied. The review covered published studies and clinical trials in pleural mesothelioma, plus some laboratory and mouse-model studies.
• Exposure: The review's subject was the tumor's immune environment and treatments aimed at it, not asbestos exposure. Asbestos was described in background as the trigger of the disease. No fiber types, jobs or doses were analyzed.
• Main results:
  • The review described the pleural mesothelioma microenvironment as generally immune-suppressed, or "cold".
  • The review stated that the microenvironment differs between epithelioid and non-epithelioid pleural mesothelioma, and that these differences reflect prognosis and response to immunotherapy.
  • Summarizing the earlier Checkmate 743 and IND 227 trials, the review reported that patients with non-epithelioid tumors gained the most from immune checkpoint inhibitor treatment, but that most patients do not benefit.
  • Citing the five-year update of the CheckMate 743 trial, the review reported that in patients treated with nivolumab plus ipilimumab, higher baseline blood levels of monocytic myeloid-derived suppressor cells (M-MDSC) were associated with a higher risk of death (HR 1.25, 95% CI 1.09 to 1.43).
  • The authors judged PD-L1 expression insufficient as a standalone predictor of treatment response in pleural mesothelioma.
  • The authors stated that tumor mutational burden has not shown significant predictive value in pleural mesothelioma.
  • Citing the earlier MAPS trial, the review reported that median overall survival was 18.8 months (95% CI 15.9 to 22.6) in the bevacizumab plus chemotherapy arm, versus 16.1 months (95% CI 14 to 17.9) in the standard chemotherapy arm.
• The authors' conclusion: The authors concluded that the tumor microenvironment plays a major role in pleural mesothelioma by creating an immune-suppressive setting. They said large multi-institutional prospective studies are needed to define reproducible immune signatures for selecting patients.
• Limitations the authors state:
  • The authors stated that most available immune signatures come from retrospective cohorts and/or mixed datasets, which limits reproducibility.
  • The authors stated that the rarity of the disease limits sample sizes, which leads to insufficient statistical power.
  • The authors noted that immune findings from pleural fluid do not fully reflect the immune picture inside the tumor.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Tumor Microenvironment, Mesothelioma, Pleural Mesothelioma, Prognosis, Immunotherapy, Biomarker, PD-L1, checkpoint inhibitors.

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