to novel precursors for its preparation, and to the preparation and use of crystal modification I of 2-{4-[2-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulphanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}-ethyl-L-alanyl L-alaninate monohydrochloride of the formula (I).