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He had a poor response to first-line treatment carboplatin-pemetrexed chemotherapy followed by ipilimumab plus nivolumab immunotherapy in the second line and carboplatin plus gemcitabine in the third line. Our patient subsequently died 10 months after diagnosis. Despite our patient having favourable prognostic markers such as BAP1 loss in epithelioid subtype mesothelioma, our patient had poor treatment response and survival, highlighting the heterogeneity within this subgroup and likely alternative underlying factors impacting outcomes.<\/jats:p>","DOI":"10.1136\/bcr-2025-264825","type":"journal-article","created":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T08:35:35Z","timestamp":1752654935000},"page":"e264825","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":1,"title":["Young-onset epithelioid type malignant peritoneal mesothelioma with loss of BAP1 gene 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