Synthon Pharmaceuticals, Inc.

Dutch Court Upholds Astellas' Xtandi Formulation Patent Against Synthon Challenge

- The District Court of The Hague dismissed Synthon's revocation claim against EP 3 725 778, successfully defending Astellas and Medivation's patent for enzalutamide formulations used in Xtandi for prostate cancer treatment. - The court rejected Synthon's arguments that the formulation was obvious, ruling that developing new enzalutamide formulations required complex empirical research with no guaranteed success at the priority date. - The patent protects solid pharmaceutical compositions containing amorphous enzalutamide with hydroxypropyl methylcellulose acetate succinate (HPMCAS) as a concentration-enhancing polymer in solid dispersion form. - This decision follows the European Patent Office Opposition Division's May 2024 ruling that maintained the patent's validity, though an appeal to the Technical Board of Appeal remains pending.