UK approach to plausibility remains unchanged despite EPO’s G2/21

The Court of Appeal found that AstraZeneca’s patent which protects its diabetes drug Dapagliflozin (Forxiga) is invalid for failing to make it plausible that the compound would be useful for the treatment of diabetes.

In reaching this decision:

• The Court continued to be bound by the jurisprudence of the Supreme Court in Warner-Lambert v Generics and the Court of Appeal in Sandoz v BMS concerning the ‘plausibility’ of a technical contribution made by a patent, when assessing both sufficiency and inventive step.

• The Court found that the EPO’s approach in G2/21 to reconcile the “ab initio implausibility” and “ab initio plausibility” lines of jurisprudence had failed, and neither the EPO nor the national courts of EPC member states have adopted a settled approach to the interpretation and application of G2/21.

• Overall, the Court appeared to be guided by the fundamental ‘patent bargain’ that a monopoly right is granted in exchange for a disclosure of the invention, with the invention needing to be in hand at the filing date.

This decision of the UK Court of Appeal therefore continues the divergence between the UK and EPO approaches to reliance on post-filed data by patentees to support sufficiency and inventive step. It further underlines that the timing of filing a patent application remains an important consideration for pharmaceutical innovators looking to retain exclusivity in the UK.