The present invention refers to a pharmaceutical composition for 4-phenylbutyric acid or its ions and a compound comprising a L-aspartate-D-alanine core structure. The pharmaceutical composition include organic salts of phenylbutyrate, polymorphs, hydrates or solvates thereof and co-crystals of phenylbutyric acid and at least one organic molecule, polymorphs, hydrates or solvates thereof, as well as their use in cancer therapy and other pharmaceutical applications.