EHNA (erythro-9-(2-hydroxy-3-nonyl)adenine hydrochloride) is another ADA inhibitor that not only acts as a competitive inhibitor of ADA enzymatic activity, but may also influence non-enzymatic functions of ADA, such as binding to adenosine receptors and DPP4 (Gracia et al., 2013); although not used clinically it has been noted to have potent anticancer effects against malignant pleural mesothelioma (Nakajima et al., 2015). This evidence concerns the gene ADA and malignant pleural mesothelioma.