| Popis: |
Background Malignant peritoneal mesothelioma (MPeM) is clinically distinct and less studied than malignant pleural mesothelioma. We report the genomic and immunophenotypic features of a prospectively collected MPeM cohort. Methods Next-generation sequencing (NGS) was performed on MPeM tumors. Genomic near-haploidization (GNH) was assessed. WT1, BAP1, mesothelin, VISTA, and PD-L1 were examined by immunohistochemistry (IHC) when tissue was available. Overall survival (OS) was stratified by selected genomic and IHC features. Results Fifty consented patients with MPeM (45 epithelioid, 5 non-epithelioid) demonstrated common alterations in BAP1 (60%; 30/50), NF2 (24%; 12/50) SETD2 (22%; 11/50), and TP53 (16%; 8/50). Seventy-six percent (38/50) of specimens were evaluable for allele-specific copy number analysis; 8% (3/38) had GNH. IHC positivity rates were 93% (37/40) for mesothelin, 96% (46/48) for WT1, 50% (19/38) for PD-L1 and 89% (34/38) for VISTA. BAP1 loss by IHC was observed in 76% (29/38), including five wildtype on NGS. Combining NGS and IHC for BAP1, OS was worse with alteration/loss compared to wildtype/retained in all patients (n=37 vs. 13, 43.8 vs. 117.3 months; p=0.04) Three of thirty patients had a pathogenic germline variant: POT1 I78T, MUTYH R109Y, BAP1 E402*. Conclusion MPeM has a distinct biology and genomic composition. CDKN2A/B alterations were rare in MPeM while BAP1, NF2, TP53, SETD2, LATS2 were common. BAP1 alteration/loss was associated with shorter survival when all patients were included. A notable minority of specimens had GNH associated with NF2, TP53, and SETDB1 mutations. Pathogenic germline mutations were found in 3 of 30 patients. |
