Immunohistochemical assessment of the PDXs showed the presence of calretinin (CalB2)-positive mesothelioma cells and expert pathological assessment of H&E staining found localized spindle cell proliferation showing atypical cells with hyperchromatic nuclei favoring sarcomatoid mesothelioma cells, which was consistent with the patient’s diagnosis. This evidence concerns the gene CALB2 and mesothelioma.