Court Of Appeal Approves Reach-Through Claim

• Published date: 15 September 2021
• Subject Matter: Litigation, Mediation & Arbitration, Trials & Appeals & Compensation
• Law Firm: J A Kemp LLP
• Author: Mr Guy Brain

A recent decision of the UK Court of Appeal (FibroGen v Akebia [2021] EWCA Civ 1279) has provided clarification on the assessment of sufficiency for claims directed to a medical use of a functionally-defined compound. In doing so, the Court found a "reach-through" claim to be sufficient, even though it may cover the use of compounds that have not yet been invented.

The key claims related to use of a compound for treating anaemia. The compound was defined partly in structural terms (a very broadly defined class of carboxamides) and partly in functional terms (requiring that the compound "inhibits [HIF-PH] enzyme activity [... and increases] endogenous erythropoietin"). The functional terms therefore identified the so-called therapeutic target considered to embody the mechanism of action of the compound.

At first instance, the claims were found to be insufficient both for lack of plausibility and for placing an undue burden on the skilled person. It was held that the skilled person must both be able reasonably to predict that substantially all compounds that satisfy the structural definition will have therapeutic efficacy, and also be able to "identify substantially all compounds covered by the claim without undue burden" (a formidable prospect given the breadth of the structural definition).

In overturning the first instance judgement on plausibility, the appeal decision sets out a three-step test: a first step of identifying what falls within the scope of a claim; a second step of determining what it means to say the invention works; and a third step of assessing whether the invention can reasonably be predicted to work with substantially everything falling within the scope of the claim. Once the scope of the claims at issue was properly interpreted as including the functional limitations, it was reasonable to predict that therapeutic efficacy would be achieved (i.e., the invention would "work") for substantially all specific compounds...