In the patient with a confirmed PR, the tumor did not harbor a PIK3CA mutation or PTEN loss but an alteration in the BAP1 gene (exon 3 p.D34fs), a potent tumor suppressor implicated in PI3K signaling pathway and in the pathogenesis of malignant mesothelioma, was found. This evidence concerns the gene BAP1 and malignant mesothelioma.