UK Patent Courts Warn Against Greedy Claims

Ever since the Decision issued back in 1997 in the case of Biogen v Medeva the concept of insufficiency has been extended, particularly in the chemical and biotech fields, to include claims that have "excessive breadth" (so-called "Biogen insufficiency"). The Courts in the UK have applied this frequently to revoke patents that they decide claim a monopoly broader than that justified by the disclosure in the patent specification.

In a Decision from April 2020, the UK High Court applied this principle to revoke four patents (EP (UK) 1 463 823, EP (UK) 2 298 301, EP (UK) 2 322 153, and EP (UK) 2 322 155) held by FibroGen Inc.To decide on sufficiency, the following two-step test was applied by Arnold LJ:

1. Determine whether the disclosure of the patent, read in the light of the common general knowledge of the skilled team, makes it plausible that the invention will work across the scope of the claim.
2. If the disclosure does make it plausible, does the evidence establish that the invention cannot be performed across the scope of the claim without undue burden?

The claims were considered to cover 10¹⁸³ different compounds, whereas only five were demonstrated in the specification to have a therapeutic effect.There was a lack of relationship between structure and function that would enable a prediction that substantially all of the claimed compounds had the therapeutic effect.It was therefore held not to be plausible that the invention worked across the scope of the claims.

The patentee argued that the claim covered only those that had the therapeutic effect specified in the claim, in other words, that the specified therapeutic effect limited the scope of the claim.However, the Court interpreted the inclusion of the therapeutic effect as a statement implying that all compounds having the claimed structure did indeed have the specified function.

This Decision provides yet another warning not to file overly broad or speculative claims.If a claim includes a functional feature, all compounds falling within the claimed structure should possess the claimed function, or there should be evidence that the function is plausible across the scope of the claim.

Two patents (EP (UK) 2 289 531 and EP (UK) 1 633 333) partially survived the insufficiency attacks of the revocation action (although EP (UK) 1 633 333 was revoked for obviousness).Infringement of EP (UK) 2 289 531 by Akebia Therapeutics and Otsuka Pharmaceutical's drug vadadustat was then considered.The exclusive licensee, Astellas Pharma Inc., argued that vadadustat infringed claim 17A under the doctrine of equivalents set out by the Supreme Court in 2017 in Actavis v Eli Lilly.

The relevant claim was limited to "Compound C", one of the five compounds demonstrated as having the claimed therapeutic effect in the patents.The inventive concept was considered to be the use of Compound C in the specified medical treatment (renal anaemia associated with kidney disease), not the use of any compound.In view of this, and the very different structures of vadadustat and Compound C, it was held that the binding and specificity properties would be expected to be quite different, and therefore that the variant (vadadustat) does not achieve substantially the same result in substantially the same way as the invention.Furthermore, Arnold LJ looked at the prosecution history and noted that the limitation that excluded the structure of vadadustat from the scope of the claim was made to establish novelty, and it would be unjust to later find that the claim covered this subject matter.

This Decision also considered issues of indirect infringement of medical use claims, and came to the conclusion that there was no evidence that vadadustat would be prescribed off label in the near future, and so there was no threat to infringe the relevant patents.The Claimant may have had a more favourable decision if it had waited until vadadustat was actually being marketed in the UK, and its actual use (rather than predicted use) could be evaluated

All six patents are currently under opposition/appeal at the European Patent Office].We look forward to seeing whether similar conclusions are reached there.