Patent matters: generic Rivaroxaban green-lit

BY DARREN SMYTH, PARTNER AND HEAD OF KNOWLEDGE AT EIP

The Court of Appeal has confirmed the Patent Court’s ruling that a Bayer patent relating to the dosage of its anticoagulant medicine rivaroxaban is invalid.

Bayer owned two patents protecting rivaroxaban. The earlier product patent, which was extended by a supplementary protection certificate, expired on 1 April 2024. The second related to a once-daily oral administration of the drug. Several pharmaceutical companies have sought revocation of that patent, which would allow them to market generic rivaroxaban products.

On 12 April 2024 the Patents Court ruled that the patent was invalid, which Bayer rapidly took to the Court of Appeal. Moving with impressive speed, the Court of Appeal heard the appeal on 16 May and delivered its written judgment on 24 May, upholding the conclusion that the patent was invalid and should be revoked.

Lord Justice Arnold, a former Patents Court judge and a chemistry graduate from the University of Oxford, wrote the judgement, with which the other two judges agreed.

The key issue for the validity of the patent was whether, in view of two poster publications pre-dating the patent application reporting the results of Phase 1 trials with rivaroxaban, it would be obvious to try rivaroxaban in a Phase 2 trial with once-daily dosing. If that step was obvious to take, then the patent would be invalid.

Notably, the posters identified the compound only by the Bayer internal code name, but at the Patents Court it had been concluded that it would have been possible to find out what chemical structure it corresponded to.

For an anticoagulant medicine, “obvious to try” necessarily includes a reasonable expectation that a proposed regimen would be sufficiently safe by avoiding an unacceptable risk of bleeding, as well as whether it would be effective to reduce incidence of thromboembolism.

The Court of Appeal agreed with the first instance that the prior publications did give sufficient expectation of success. Indeed, one of the posters explicitly stated ‘Some parameters […] indicate a long-lasting pharmacodynamic effect […] which suggests suitability for a once-daily dosing regimen.’