MTAP staining demonstrated generally good concordance between the cytologic and surgical specimens and appears to be useful in the diagnosis of mesothelioma on effusion specimens.
We performed MTAP immunohistochemistry on 20 benign mesothelial lesions and 99 malignant mesotheliomas from five mesothelioma centers in four countries, and each MTAP stain was independently interpreted by four pathologists.
The homozygous co-deletion of MTAP, encoding the enzyme methylthioadenosine phosphorylase, in approximately 90% of mesotheliomas with P16/CDKN2A loss has potential therapeutic applications because MTAP-deficient tumors may be responsive to inhibitors of de novo AMP synthesis.
Thus, the particularly high prevalence of MTAP codeletion in mesothelioma makes it an ideal candidate for trials of targeted therapy using inhibitors of de novo AMP synthesis (e.g., L-alanosine).