CTLA4 and mesothelioma: In former experiments signs of necrosis and release of inflammatory mediators were also measured in tumors after treatment with PE-based immunotoxins (Luther et al., 2010; Leshem et al., 2018) and simultaneous treatment of mice bearing mesothelioma tumors with the anti-mesothelin immunotoxin SS1P and an checkpoint inhibitor against the Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA-4) resulted in enhanced antitumor activity compared to monotherapies and in protection from tumor recurrence (Leshem et al., 2018).