On May 24, 2024, UK Court of Appeal affirmed High Court’s decision of invalidity of once-daily method of use rivaroxaban patent.

Background: This case involves the revocation of European Patent (UK) No. 1 845 961 (the “Patent”), owned by Bayer and covering the use of rivaroxaban (marketed as Xarelto) for treating thromboembolic disorders through once-daily administration. The Patent was challenged by generic medicine suppliers who sought to market generic versions of rivaroxaban. On April 12, 2024, His Honour Judge Hacon of the High Court revoked the Patent, concluding that it was invalid. Bayer appealed this decision, arguing that the Patent should remain in force, as its claims were not obvious based on existing scientific literature and knowledge.

Appeal: Bayer argued that the judge failed to apply the correct legal standards in determining whether the Patent was obvious in light of prior art and common general knowledge. The core issue was whether a skilled team, upon reviewing the Harder article and Kubitza posters, would find it obvious to include a once-daily dosing regimen of rivaroxaban in a Phase II clinical trial with a reasonable expectation of success in terms of efficacy and safety.

The Court of Appeal dismissed Bayer’s appeal, supporting the High Court’s decision. The key reasons include:

1. Detailed Evidence and Expert Testimony:
   • Bayer contended that the judge erred in his assessment of expert testimonies, particularly favoring the respondents’ experts over Bayer’s.
   • Judge’s mainly relied on respondents’ experts, who argued that the prior art suggested a reasonable expectation that once-daily dosing of rivaroxaban could be effective and safe.
2. Obviousness and Prior Art:
   • Bayer’s experts argued that prior arts would not lead a skilled team to pursue a once-daily regimen due to safety and efficacy concerns.
   • Bayer argued that the judge incorrectly stated that the skilled team would perceive no technical barrier to the claimed invention, whereas other findings suggested uncertainty about the therapeutic window and safety of once-daily dosing.
   • The Court of Appeal disagreed with Bayer’s interpretation, clarifying that the judge’s statement in [124] merely indicated that a wide range of doses could be tested in theory. However, in practice, the skilled team would not adopt a “scattergun” approach due to unknown risks associated with the therapeutic window.
   • It was conventional to explore various dosing regimens in Phase II trials to determine the optimal dosage.
   • The judge concluded, based on evidence, that the prior art suggested a 30 mg once-daily dose could be effective and safe. Bayer’s disagreement with this conclusion did not demonstrate any error in the judge’s application of the law or principles.
3. Rejection of Bayer’s Grounds for Appeal:
   • Bayer was denied permission to amend their grounds of appeal, which included a challenge to the judge’s factual findings.
   • The Court found these factual findings rational and supported by evidence.

Court thus dismissed the appeal, affirming the original judgment that the Patent was obvious and invalid.

“Court decision”