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Updated: Sep 25, 2025
Generation and Expansion of Primary, Malignant Pleural Mesothelioma Tumor Lines
Published on: April 21, 2022
Expression of PD-L1 in Patients With Malignant Peritoneal Mesothelioma: A Pilot Study
Victor P Gazivoda1, Aaron W Kangas-Dick1, Alissa A Greenbaum1
1Division of Surgical Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.
Introduction:
Frequency of PD-L1 expression and the role of immunotherapy in malignant peritoneal mesothelioma (MPM) have not been well characterized. The purpose of this study was to determine PD-L1 expression in patients with MPM and perform an exploratory analysis for associations between PD-L1 and its biological behavior in MPM.
Methods:
Tumor samples were collected from patients undergoing surgical interventions between January 2018 and June 2020. Specimens were stained with anti-PD-L1 antibodies (Dako 22c3) and positivity was determined by tumor proportion score (TPS) or combined positive score (CPS) being ≥1%.
Results:
Twenty one samples were obtained from 21 patients. Sixteen of 21 (76%) samples were CPS positive and 9 of 21 (43%) were TPS positive. Three samples had more aggressive biphasic/sarcomatoid histology and a high CPS and TPS (CPS: 3, 75, 95%; TPS: 2, 60, 90%). On an exploratory analysis, as the CPS or TPS threshold increased, there was a trend towards worse survival.
Conclusions:
MPM has a high frequency of PD-L1 expression, which may be associated with more aggressive tumor biology. These data provide the foundation for continued evaluation of checkpoint inhibition in patients with MPM.
Insights
Malignant peritoneal mesothelioma (MPM) frequently expresses PD-L1, potentially linked to aggressive tumor biology. This suggests immunotherapy may benefit MPM patients, warranting further investigation.
Area of Science:
- Oncology
- Immunology
- Pathology
Background:
- Malignant peritoneal mesothelioma (MPM) is a rare cancer.
- The expression of PD-L1 and its role in immunotherapy for MPM are not well understood.
Purpose of the Study:
- To determine the frequency of PD-L1 expression in MPM.
- To explore the association between PD-L1 expression and tumor biology in MPM.
Main Methods:
- Collected tumor samples from 21 MPM patients between January 2018 and June 2020.
- Used anti-PD-L1 antibodies (Dako 22c3) for immunohistochemical staining.
- Assessed PD-L1 positivity using tumor proportion score (TPS) or combined positive score (CPS) ≥1%.
Main Results:
- 76% of samples were CPS positive and 43% were TPS positive.
- Three aggressive biphasic/sarcomatoid tumors showed high CPS and TPS values.
- Exploratory analysis indicated a trend towards worse survival with increasing CPS or TPS thresholds.
Conclusions:
- MPM exhibits a high frequency of PD-L1 expression.
- PD-L1 expression may correlate with more aggressive tumor characteristics in MPM.
- These findings support further research into checkpoint inhibition therapies for MPM.
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