The contribution of GITR/GITRL in MPM needs to be further elucidated by knockin and knockout experiments with transfection of GITR/GITRL gene into GITR−GITRL− mesothelioma cells and CRISPR knockout of the GITR/GITRL genes in highly expressing mesothelioma cells. Here, TNFRSF18 is linked to mesothelioma.