PD-L1 and BAP1 as Prognostic Biomarkers in Malignant Pleural Mesothelioma

Our plain-English summary of PD-L1 and BAP1 as Prognostic Biomarkers in Malignant Pleural Mesothelioma, by M. Gajić, V. Ćeriman Krstić, N. Samardžić, et al (Cells, 2026).

The study

• Authors: M. Gajić, V. Ćeriman Krstić, N. Samardžić, I. Soldatović, S. Glumac, M. Jovanović, M. Savić, M. Stjepanović, S. Popević, R. Stević, N. Čolić, K. Lukić, V. Milenković, I. Milivojević, I.S. Radovanović, D. Jovanović
• Journal: Cells
• Published: 2026;15(2)
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is a very aggressive tumor. The prognostic value of PD-L1 and BAP1 expression has been investigated in many studies. A retrospective study was conducted that analyzed PD-L1 and BAP1 expression as prognostic biomarkers in patients with MPM. The study included 53 patients with MPM. PD-L1 expression ≥ 1% was found in 39.6%, and BAP1 loss was found in 81.1% of patients. The median overall survival (mOS) was 11 months. Subtype of MPM (p = 0.045), early tumor stage (p = 0.049), therapy (p = 0.002), and good PS (0-1) (p = 0.012) were associated with better survival. Expression of PD-L1 and BAP1 did not show statistical significance regarding OS, but OS was numerically shorter in patients with PD-L1 ≥ 10% (5 vs. 12 months) and longer in patients with BAP1 loss (12 vs. 4 months). In patients with PD-L1 ≥ 1% and BAP1 loss, the median progression-free survival (mPFS) was numerically longer (10 vs. 7 months) but in patients with PD-L1 ≥ 1% and BAP1 positivity, PFS was statistically significantly shorter (1 vs. 7 months, p = 0.048). Our results did not show that PD-L1 and BAP1 are prognostic biomarkers for MPM, but positive PD-L1 expression and BAP1 loss were associated with worse survival in patients with MPM.

In plain English

This retrospective study from Serbia analyzed the 53 of 89 patients with malignant pleural mesothelioma (diagnosed 2008 to 2018) whose tumor tissue was available. The article reports no asbestos exposure information for these patients. Tumor tissue was tested for two markers, PD-L1 and BAP1. PD-L1 at 1% or more was found in 39.6% of patients, and loss of BAP1 in 81.1%. Median overall survival was 11 months. Tumor subtype, stage, treatment and fitness (performance status) were associated with survival. Neither marker was statistically significantly linked to overall survival. Median survival was 5 versus 12 months for PD-L1 at 10% or more versus below 10%, and 12 versus 4 months with versus without BAP1 loss. Patients with PD-L1 of 1% or more whose BAP1 was not lost had significantly shorter progression-free survival (1 versus 7 months, p = 0.048). The authors concluded that the markers did not predict one-year survival. They also wrote that PD-L1 expression and BAP1 loss went with worse survival, though their results showed numerically longer survival with BAP1 loss. The authors noted the small, retrospective design and mostly epithelioid cases.

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: Retrospective study of tumor markers and survival in patients with malignant pleural mesothelioma
• Who was studied: 53 patients with malignant pleural mesothelioma who had tumor tissue available, out of 89 patients, at the Clinic for Pulmonology, University Clinical Center of Serbia. All were over 18, diagnosed between 2008 and 2018, and untreated at inclusion. Mean age was 65 years, 69.8% were male, and 77.4% had the epithelioid subtype.
• Exposure: Asbestos or other environmental exposure was not assessed for the study patients. The factors studied were tumor expression of PD-L1 (positive at a tumor proportion score of 1% or more, 'high' at 10% or more) and BAP1 (present versus lost), measured by immunohistochemistry on tissue from pleural biopsy or surgery.
• Main results:
  • PD-L1 at 1% or more was found in 39.6% of the 53 patients (21 patients), and PD-L1 at 10% or more in 18.9% (10 patients).
  • BAP1 loss was found in 81.1% of patients (43 of 53).
  • Median overall survival for the whole group was 11 months.
  • Median progression-free survival for the whole group was seven months.
  • Patients with performance status 0 to 1 had significantly longer overall survival than those with performance status 2 to 3 (12.5 vs. 1 months, p = 0.012).
  • Patients treated with multimodality treatment had the longest overall survival (26.5 months), compared with chemotherapy, surgery or best supportive care (p = 0.002).
  • Early-stage patients had significantly longer overall survival than late-stage patients. The article prints different figures for this comparison in different places.
  • Histological subtype was significantly associated with survival. Patients with the sarcomatoid subtype had the shortest overall survival (1 month).
  • PD-L1 at 1% or more did not significantly affect overall survival compared with PD-L1 below 1% (12 vs. 11 months, p = 0.799).
  • Overall survival was shorter with PD-L1 at 10% or more than with PD-L1 below 10%, but the difference was not statistically significant (5 vs. 12 months, p = 0.464).
  • Median overall survival was longer in patients with BAP1 loss than in those with BAP1 present (12 vs. 4 months), but the difference was not statistically significant (p = 0.541).
  • Patients with PD-L1 at 1% or more and BAP1 positivity had significantly shorter median progression-free survival (1 vs. 7 months, p = 0.048). The effect on overall survival was not significant (p = 0.457).
  • In patients with PD-L1 at 1% or more and BAP1 loss, progression-free survival was numerically longer but not statistically significant (10 vs. 7 months, p = 0.589).
  • PD-L1 and BAP1 expression did not indicate one-year survival (p = 0.872 and p = 0.782).
• The authors' conclusion: The authors concluded that histological subtype, stage, performance status and multimodality treatment could be prognostic factors for overall and progression-free survival. They concluded that PD-L1 and BAP1 are not indicators of one-year survival, but that PD-L1 expression and BAP1 loss are associated with worse survival. They called for new prognostic factors to be found.
• Limitations the authors state:
  • The study was retrospective, with a relatively small number of patients.
  • In most cases PD-L1 and BAP1 were tested on small biopsy samples, so the authors said the test results should be interpreted with caution.
  • Most cases were of the epithelioid subtype, so the authors said the results cannot be generalized to all patients with malignant pleural mesothelioma.
  • The patients were not treated with immunotherapy, which new guidelines recommend as the first treatment option.

Topics

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

Medical terms in this study, explained in our Lexicon: PD-L1, BAP1, Biomarker, Pleural Mesothelioma, Median Overall Survival, Statistical Significance, Progression-Free Survival.

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• A Tumor-Specific Neo-Antigen Caused by a Frameshift Mutation in BAP1 Is a Potential Personalized Biomarker in Malignant Peritoneal Mesothelioma — J. Lai, Z. Zhou, et al. (2016)
• BAP1 immunohistochemistry has limited prognostic utility as a complement of CDKN2A (p16) fluorescence in situ hybridization in malignant pleural mesothelioma — S.M. McGregor, J. McElherne, et al. (2017)
• Altered Nuclear Expression of the Deubiquitylase BAP1 Cannot be Used as a Prognostic Marker for Canine Melanoma — N. Jama, N. Farquhar, et al. (2018)
• Retrospective response analysis of BAP1 expression to predict the clinical activity of systemic cytotoxic chemotherapy in mesothelioma — N. Kumar, D. Alrifai, et al. (2019)
• Diagnostic Utility of BAP1, EZH2 and Survivin in Differentiating Pleural Epithelioid Mesothelioma and Reactive Mesothelial Hyperplasia: Immunohistochemical Study — S.A. Hakim, H.H. Abou Gabal (2021)

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