Pfizer faces a setback in its plans to launch its hemophilia gene therapy drug in the UK after the UK High Court rejected its attempt to invalidate a patent held by uniQure. The patent, EP 3 581 650, covers a method for producing a "Factor IX polypeptide mutant" for treating hemophilia B, which forms the basis of uniQure's drug *Hemgenix*. Pfizer's gene therapy product, *Beqvez* (formerly *Durveqtix*), was approved by the European Medicines Agency in July 2024, but has not yet launched in the UK. Pfizer had challenged the patent, claiming it lacked an inventive step, but the court upheld the validity of EP 650 and found that Pfizer's product infringed it. Pfizer has indicated its intention to appeal the decision. Meanwhile, the European Patent Office (EPO) has indicated in its preliminary opinion that the patent is likely valid, with an oral hearing scheduled for October 2025. A ruling is also expected in parallel Dutch proceedings later this month.