WCLC 2025 - Posters & ePosters-P3.14.02 Clinical Implications of BAP1 Status in Pleural Mesothelioma (PM)

Pdf Summary

This retrospective study analyzed the clinical implications of BRCA1-associated protein 1 (BAP1) status in 257 patients with pleural mesothelioma (PM) treated at Vall d’Hebron Hospital from 2005 to 2024. PM is a rare, aggressive cancer typically associated with poor prognosis, and BAP1 mutations represent its most frequent molecular alteration. Prior studies have reported conflicting results regarding the prognostic role of somatic BAP1 mutations, and while BAP1 is recognized as a predictive biomarker for platinum-based chemotherapy response, its predictive value for immunotherapy (IO) remains unclear.<br /><br />Among the 50 patients evaluated for BAP1 status via immunohistochemistry, 56% showed BAP1 loss. Median overall survival (OS) for the entire cohort was 21.3 months. Key prognostic factors identified included performance status, clinical stage, histology, and cisplatin treatment. However, BAP1 status did not significantly influence prognosis: median OS was 21.8 months for BAP1-loss patients versus 21.0 months for those retaining BAP1 (p=0.7).<br /><br />Furthermore, when assessing therapeutic outcomes, no significant differences in survival were observed based on BAP1 status in patients receiving first-line platinum chemotherapy (20.9 months for BAP1-positive vs. 22.5 months for BAP1-loss, p=0.9). Among 14 patients treated with first-line IO, median OS was 19.5 months with BAP1 loss versus 37.6 months for BAP1 retention (p=0.3). Similar non-significant results were found in the second-line IO subgroup and time-dependent analyses.<br /><br />The study concludes that, in this real-world cohort, BAP1 status neither predicts prognosis nor guides selection of platinum or IO treatments in PM. Larger confirmatory studies are warranted to clarify BAP1’s predictive significance for immunotherapy in this disease.

Asset Subtitle

Susana Cedres

Meta Tag

Speaker Susana Cedres

Topic Mesothelioma, Thymoma, and Other Thoracic Tumors

Keywords

Pleural Mesothelioma

BAP1 Status

BRCA1-associated protein 1

Immunohistochemistry

Prognosis

Platinum-based Chemotherapy

Immunotherapy

Overall Survival

Cisplatin Treatment

Predictive Biomarker