Broad functional claiming at the EPO (T 0835/21)

The ever-present question for IP in certain technical fields is how much data is needed to support a patent application. In technically challenging fields, such as biotech, there will often be some doubt that a skilled person will be able to make the invention or that the invention actually has the technical effect it is purported to have. However, in some cases, the amount of data needed to overcome this doubt to support a patent application may still be surprisingly minimal. This principle is illustrated by the recent Board of Appeal decision in T 0835/21. In this case, the Board of Appeal maintained a broad functional claim for a genus of antibodies, based on only minimal data in the application as filed. In contrast to the US Supreme Court decision in Amgen v Sanofi, the EPO does not consider the potential for a large number of possible embodiments falling under a broad claim as conferring insufficiency on the claim in-and-of itself. 

Case background

The case in T 0835/21 related to the sufficiency and inventive step of an antibody epitope claim, i.e. a claim defined by the functional binding of the antibodies. The patent (EP2567709, Novartis) related to anti-LRP6 antibodies and their use in the treatment of cancer. The question on appeal was whether a broad functional epitope claim, that did not define the structure or sequence of the claimed antibodies, was sufficiently disclosed and inventive. 

Sufficiency - Tedium is not the test

Claim 1 as granted was an epitope claim (IPKat). The claim particularly specified an antibody or an antigen-binding fragment thereof specifically binding to a defined epitope of LRP6. In considering whether the invention was sufficiently disclosed (Article 83 EPC), the Board of Appeal confirmed that the test for sufficiency is whether the skilled person can make the claimed product. In the case in question, "the skilled person must be able to prepare the claimed monoclonal antibody" (r. 23). 

The sufficiency requirement is therefore a relatively low bar at the EPO. In this case, the application as filed only disclosed 2 example antibodies having the functional features of the claim. Neither the structures or sequences of these examples was provided. On the contrary, the Board of Appeal accepted that the application as filed did not provide a reproducible example of the claimed invention. However, the Board did not consider the provision of a reproducible example as necessary for the sufficiency requirement (r. 27). The Board of Appeal instead reiterated the common EPO view that it is generally routine to make new antibodies to a known target (r. 34) (Cf. Amgen v Sanofi, IPKat). 

The Board of Appeal thus concluded that the skilled person would be able to use their common general knowledge in view of the application as filed in order to make the claimed antibody. The Board noted that whilst this task "may be tedious", tedium did not amount to undue burden if the skilled person would be directed towards success by the application as filed (r. 36, citing T 544/12; Reasons 4.8). 

The Board of Appeal also dismissed a sufficiency attack against a medical use claim for the antibody. The Board of Appeal was satisfied that the known involvement of the signalling mechanism targeted by the antibody in cancer constituted sufficient support for the claim (r. 42). 

EPO sufficiency versus UK "plausibility" 

The Board of Appeal in T 0835/21 therefore confirmed the low bar sufficiency for a product claim. In stark contrast to the US enablement requirement applied in Amgen v Sanofi, even a very broad product claim limited only by the function of the product, may easily satisfy the EPO sufficiency requirement.

Notably, however, the UK Court of Appeal decision in Sandoz v BMS ([2023] EWCA Civ 472) diverged from the established principles of EPO case law on sufficiency. Lord Justice Arnold in Sandoz found that the UK plausibility requirement necessitates that the technical effect of the claim be "plausible" in order for the claim to be sufficiently disclosed (IPKat). In direct contrast to the EPO case law applied in T 0835/21, the sufficiency requirement for a product claim in Sandoz was thus not a simple test of whether the skilled person could make the claimed product. UK sufficiency as outlined in Sandoz required the extra criteria of a plausible technical effect over the whole scope of the claimed invention (IPKat). 

Antibody, target & epitope

Inventive step - Providing the solution to a problem 

Whilst the sufficiency bar for functional antibody claims may be relatively low under EPO case law, the same cannot be said for inventive step. The EPO considers it generally routine to make new antibodies for a known target. It can therefore be challenging for applicants to establish the inventive step of a new antibody product. However, if it can be shown that the new antibody product is not just an alternative, but has functional features providing a solution to a problem, inventive step becomes more achievable. Broad functional language included in the claim can do the heavy lifting for an inventive step argument, if the functional language can be linked to an advantageous technical effect. 

In T 0835/21, the closest prior art was a document disclosing an antibody binding the same target, but to a different epitope sequence within that target. The technical effect of binding the different epitope was a difference in the inhibitory effects of the antibody on the particular signalling pathways most relevant to the treatment of cancer. 

The Board of Appeal was convinced that the prior art did not suggest that targeting the particular epitope specified in the claim would have the identified technical effect. The Opponent argued that a skilled person would routinely screen antibodies to have the specified technical effect. However, the Board of Appeal did not consider the prior art as disclosing any link between the targeted effect of the claimed antibody and the improved treatment of cancer. By contrast, the application as filed did provide evidence of such a link. 

Therefore, in this case, the Board of Appeal was convinced of the inventive step of the claimed antibody. The inventive step argument was based on the identification of a new epitope in a known target linked to a specific technical effect. The decision in T 0835/21 therefore confirms pre-existing EPO case law that the identification of a new target/epitope and its technical effect may support inventive step for a broad functional antibody product claim. 

Final thoughts

The decision in T 0835/21 is a text-book example of how broad functional claim language may be used to good effect in Europe. The US Supreme Court decision in Amgen v Sanofi concluded that making all of the antibodies falling under the epitope claim of Amgen's patent would be undue burden for the skilled person. As demonstrated in T 0835/21, the EPO will often take the opposite view, and require surprisingly minimal direction in the application as filed as to how to make antibodies falling under an epitope claim. It is necessary only for the skilled person to be able to perform the necessary screens and functional assays (IPKat). In T 0835/21, the invention was also based on the identification of the new technical effect of antibodies binding to a newly defined epitope. The functional aspects of the invention therefore also allowed the patentee to also cross the inventive step hurdle.

Further reading

EPO Sufficiency versus UK Plausibility

Epitope claims

Broad functional claiming at the EPO (T 0835/21) Broad functional claiming at the EPO (T 0835/21) Reviewed by Rose Hughes on Friday, September 29, 2023 Rating: 5

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