Rivaroxaban in the UK Court of Appeal: consideration of ethical barriers to invention

The Court of Appeal recently upheld Mr Justice Hacon’s finding that Bayer’s patent for a once-daily administration of rivaroxaban, an anti-coagulant medicine, was obvious. The unusual feature of this case was that there was no technical barrier to the invention, and the analysis considered whether the skilled team would have been held back by an ethical barrier by reference to the need for ethics committee approval of a Phase II trial.

A key takeaway from this decision is that ethical considerations are unlikely to form a standalone ground in the assessment of prospects of success for inventive step. However, the safety considerations for patients that fall within this ethical assessment are relevant, as the assessment of “success” for the usual test for obviousness would take such factors into account. 

Background

Rivaroxaban (trade mark: XARELTO), is Bayer’s largest selling drug, and the fourth best-selling drug in the world. Protection under the original patent for rivaroxaban (as extended by an SPC) expired on 1 April 2024. However this case concerned a further patent from Bayer claiming the use of rivaroxaban for the treatment of thromboembolic disorder, using a once-daily administration (EP (UK) 1,845,961, the “Patent”).  

Sandoz and a number of other pharmaceutical companies applied to revoke the Patent. If valid, the Patent would prevent them from supplying generic rivaroxaban for once daily administration, but not from supplying it for twice (or more) daily administration, following the expiry of the original patent and SPC protection. 

On 12 April 2024, Mr Justice Hacon revoked the Patent for lack of inventive step. The efficacy of once-daily administration had been disclosed in prior art conference posters reporting on Phase I trials. Hacon J held that, having read those posters, it would have been obvious for the skilled team to try such a dosage regime in Phase II trials. 

Bayer’s appeal

Bayer sought to appeal on a number of grounds. The key ground of note, and the unusual feature of this case, was the consideration of ethics as part of the usual assessment of whether there would be a reasonable prospect of success. 

The ultimate question was whether, having read the posters, the…