# Immune Checkpoint Inhibitors in Malignant Pleural Mesothelioma: Efficacy, Real-World Outcomes, and the Search for Predictive Biomarkers

## TL;DR

This paper reviews how immunotherapy is changing treatment for a rare lung cancer called mesothelioma, but notes that results vary and better biomarkers are needed to guide treatment.

## Contribution

The paper highlights the complex interplay of genomic, immunologic, and clinical factors affecting immunotherapy response in mesothelioma and emphasizes the need for integrated molecular profiling.

## Key findings

- Combination immunotherapy (nivolumab plus ipilimumab) improves survival in non-epithelioid mesothelioma compared to chemotherapy.
- Genomic alterations like BAP1, NF2, and CDKN2A influence tumor response to immunotherapy.
- Current biomarkers lack predictive value for immunotherapy response in mesothelioma.

## Abstract

Malignant pleural mesothelioma is a rare and aggressive cancer, often linked to asbestos exposure, for which treatment options have long been limited. Immunotherapy has introduced new opportunities, but its benefits vary widely among patients and are often less pronounced in routine clinical practice than in clinical trials. Outcomes appear to depend on several factors, including tumor subtype, patient characteristics, and the biological features of the tumor microenvironment. Genetic alterations such as BAP1, NF2, and CDKN2A may influence how tumors respond to immunotherapy, yet no biomarker is currently reliable enough to guide treatment decisions. A deeper understanding of how genetic changes, immune activity, and clinical features interact will be essential for developing more personalized therapeutic strategies and improving future outcomes.

Immunotherapy has significantly reshaped the management of malignant pleural mesothelioma (MPM), offering new therapeutic opportunities after decades in which platinum–pemetrexed chemotherapy represented the only systemic option. However, clinical benefit remains markedly heterogeneous, with outcomes strongly influenced by histologic subtype, patient characteristics, and real-world treatment conditions. Evidence from monotherapy trials has been inconsistent, whereas combination approaches—particularly nivolumab plus ipilimumab—have demonstrated improved survival compared with chemotherapy, mainly in non-epithelioid tumors. Nevertheless, real-world data consistently show lower efficacy and higher toxicity than registrational studies, especially among elderly and unselected populations. Recent translational work has highlighted the relevance of the tumor microenvironment and recurrent genomic alterations such as BAP1, NF2, and CDKN2A in shaping immune activity and potentially modulating response to immune checkpoint inhibitors. Transcriptomic signatures and circulating biomarkers—including soluble mesothelin-related peptide—have shown prognostic associations but no validated predictive value. Overall, current evidence suggests that sensitivity to immunotherapy in MPM arises from a complex interplay of genomic, immunologic, and clinical factors, and that no biomarker is yet suitable for guiding treatment decisions. Prospective studies integrating molecular and immune profiling will be essential to refine patient selection and advance toward a more rationally personalized use of immunotherapy