Efficacy of Immunotherapy Versus Chemotherapy in Advanced Pleural Mesothelioma: A Turkish Oncology Group (TOG) Study

Our plain-English summary of Efficacy of Immunotherapy Versus Chemotherapy in Advanced Pleural Mesothelioma: A Turkish Oncology Group (TOG) Study, by Z. Kalkan, S. Ebinc, M. Arcagok, et al (Medicina, 2025).

The study

• Authors: Z. Kalkan, S. Ebinc, M. Arcagok, A. Bilici, O. Yildiz, S. Kilickap, D.C. Guven, A.M. Tatli, A.T. Sumbul, N.M. Mandel, A. Ozturk, M. Bardakci, S. Karakaya, M.A. Kaplan
• Journal: Medicina
• Published: 2025;61(4)
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background and Objectives: This study aimed to evaluate the effectiveness of immunotherapy compared to chemotherapy across different treatment lines in patients with pleural mesothelioma. It also sought to identify factors influencing the success of immunotherapy, such as histological subtype, PD-L1 expression, type of asbestos exposure, and metastatic status. Materials and Methods: A retrospective analysis was conducted with 60 patients diagnosed with pleural mesothelioma. Data on age, gender, histological subtype, and asbestos exposure were collected for all patients and PD-L1 expression was assessed in a subset of patients. Patients received either chemotherapy or immunotherapy as first-, second-, and third-line treatments, and progression-free survival (PFS) and treatment responses were evaluated. Results: Among the 60 patients, 35 (58.3%) were male and the median age was 59 years. The majority (71.7%) had epithelioid histology and 28.3% had distant metastases. Asbestos exposure was documented in 65% of the cases. PD-L1 expression of ≥1% was found in 13 of 17 patients tested. First-line treatments included immunotherapy for 11 patients and chemotherapy for the others, with immunotherapy achieving median PFS of 9 months versus 6 months for chemotherapy, although the difference was not statistically significant. In third-line treatments, immunotherapy significantly outperformed chemotherapy with median PFS of 6 months compared to 3 months (p = 0.048). Absence of metastasis and prior asbestos exposure in an endemic region were linked to better immunotherapy outcomes. Conclusion: Immunotherapy shows increased efficacy in later treatment lines for pleural mesothelioma, especially for patients without metastases or with prior endemic asbestos exposure. Tailored therapeutic strategies should be further explored in prospective studies.

In plain English

This retrospective study by the Turkish Oncology Group reviewed records of 60 adults with metastatic or unresectable pleural mesothelioma treated at eight centres in Türkiye between January 2014 and January 2024, all of whom received immunotherapy at some stage. In first-line treatment, median progression-free survival was 9 months with immunotherapy (11 patients) and 6 months with chemotherapy (49 patients). This difference was not statistically significant (p = 0.50). In second-line treatment it was 3 versus 6 months (p = 0.30). In later lines it was 6 months with immunotherapy (22 patients) versus 3 months with chemotherapy (10 patients), p = 0.048. Asbestos exposure from living in an endemic region was recorded for 39 patients (65%); the rest had an unknown mode of exposure. In multivariate analysis, though not in univariate analysis, endemic-region exposure and absence of distant metastasis were associated with longer progression-free survival on immunotherapy. The authors concluded that immunotherapy gave results comparable to chemotherapy and that these patients may respond better. They noted the small, retrospective design without a control arm.

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 observational multicentre study (Turkish Oncology Group) using hospital archive records
• Who was studied: 60 patients aged 18 or older with metastatic or unresectable pleural mesothelioma who received immunotherapy at any stage of treatment, at eight centres in Türkiye, January 2014 to January 2024. There were 35 men and 25 women, the median age was 59, and 43 (71.7%) had epithelioid histology.
• Exposure: Asbestos exposure type was recorded as living in an endemic region for 39 patients (65%) and other for 21 (35%). The text describes the remaining patients as having an unknown mode of exposure. Fiber types were not measured in this study. In the discussion, the authors cite earlier studies stating that Turkish 'white soil' contains tremolite asbestos fibres, often contaminated with chrysotile. The treatments compared were immunotherapy (nivolumab, nivolumab plus ipilimumab, pembrolizumab) and chemotherapy (platinum-based, with or without bevacizumab, or other chemotherapy).
• Main results:
  • First-line treatment: median progression-free survival was 9 months with immunotherapy (11 patients) and 6 months with chemotherapy (49 patients), p = 0.50 (not statistically significant). Median overall survival was 15 versus 21 months (p = 0.49).
  • First-line objective response rate was 54.5% with immunotherapy and 55.1% with chemotherapy (p = 0.97).
  • Second-line treatment: median progression-free survival was 3 months with immunotherapy (27 patients) and 6 months with chemotherapy (30 patients), p = 0.30.
  • Subsequent (third or later) lines, 32 patients: median progression-free survival was 6 months with immunotherapy (22 patients) and 3 months with chemotherapy (10 patients), p = 0.048. Response rates were 47.6% and 30% (p = 0.35).
  • In univariate analysis, none of the variables tested were significantly related to progression-free survival on immunotherapy. These variables included age, sex, smoking, histology, PD-L1, asbestos exposure type, metastasis, line, immunotherapy type and steroid use.
  • In multivariate analysis, absence of distant metastasis was associated with progression-free survival on immunotherapy (HR 4.59; 95% CI 1.02–20.7; p = 0.04).
  • In multivariate analysis, asbestos exposure from residence in an endemic area was associated with progression-free survival on immunotherapy (HR 4.16; 95% CI 1.04–16.7; p = 0.04). In the subgroup table, median progression-free survival was 4 months in both the endemic-region and other-exposure groups (p = 0.62).
  • Immunotherapy in any line, combination (nivolumab plus ipilimumab, 7 patients): response rate 57.1%, median progression-free survival 4 months, median overall survival 31 months. Monotherapy (53 patients): 37.7%, 4 months and 18 months. None of these differences was statistically significant.
  • PD-L1 was tested in 17 patients; 13 had a PD-L1 level of 1% or more.
  • Safety: no grade 4 immunotherapy-related side effects were observed. Grade 3 pneumonitis occurred in three patients (printed as 5.1%).
• The authors' conclusion: The authors concluded that immunotherapy achieved response rates, progression-free survival and overall survival comparable to chemotherapy. They also concluded that patients with endemic asbestos exposure and without distant metastasis may show enhanced responsiveness to immunotherapy.
• Limitations the authors state:
  • Retrospective design and no control arm
  • Immunotherapy was used at different stages of treatment, and treatments were heterogeneous
  • Different chemotherapy options were used, and the number of patients was relatively small
  • Genetic factors such as BAP-1 were not analysed
  • Relatively few patients had known PD-L1 levels
  • The combination immunotherapy group was small

Topics

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

Medical terms in this study, explained in our Lexicon: Immunotherapy, Chemotherapy, Pleural Mesothelioma, Histological Subtype, PD-L1, Asbestos Exposure, Progression-Free Survival, Epithelioid.

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