PREP and celiac disease: However, the use of single PSPs did not achieve the complete hydrolysis of gliadins, and only the discovery of cysteine peptidase from Hordeum vulgare (EP-B2) in 2006 [65,66] allowed for the creation and testing of a dosage form for celiac disease treatment, which was based on a mixture of prolyl oligopeptidase from S. capsulata and cysteine peptidase from H. vulgare (EP-B2) (ALV003 Alvine, USA) and which is now under clinical trial [67,68].