7.3. Level of disclosure required for antibodies

In T 431/96 the skilled person seeking to reproduce the invention would have had to produce monoclonal antibodies by routine methods and test them singly in an assay. Although this might possibly involve some tedious and time-consuming work, it was nothing out of the ordinary since the techniques for the production and selection of hybridomas were common routine techniques at the priority date of the patent in suit.

The board found that the essential issue to be considered in T 601/05 of 2 December 2009 date: 2009-12-02 was whether or not the patent enabled the production of human monoclonal antibodies binding with high affinity to soluble TNF and, consequently, whether or not the skilled person could practise the invention over the whole scope of the claim (following T 792/00). On the evidence before the board it did not.

In T 1466/05 the question arose whether the availability of a hybridoma producing one specific antibody together with a general description of the epitope recognised by this antibody put the skilled person in the position to obtain further antibodies with the same specificity. The board observed that similar questions had arisen in various cases decided by the boards of appeal, and different boards had given different answers depending on the circumstances of each case (T 510/94, T 513/94, T 349/91, T 716/01).

In T 1466/05 the claim was not restricted to monoclonal antibodies defined by reference to the deposited hybridoma. As the application did not disclose any specific antigen for preparing further antibodies as claimed, the board considered that a skilled person seeking to prepare such antibodies would have had to embark on a research programme without any teaching in the application as how to achieve the desired specificity which amounted to an undue burden (cited in this respect by T 760/12).

Concerning the second medical use claims (claim 6 in the "Swiss-type" format, claim 7 in the purpose-restricted product claim format) in T 760/12, the technical effect, which was the therapeutic effect, was expressed in the claim. When the technical effect is expressed in the claim, the issue of whether this effect is indeed achieved over the whole scope of the claim is a question of sufficiency of disclosure (G 1/03, OJ 2004, 413, point 2.5.2 of the Reasons). Hence, under Art. 83 EPC, unless this is already known to the skilled person at the priority date, the application must disclose the suitability of the product to be manufactured for the claimed therapeutic application (T 609/02, point 9 of the Reasons). The board concluded that it was not sufficiently disclosed in the patent that a single monoclonal antibody as defined in the claim potentially exerted the therapeutic effect as claimed.

The claim at issue in T 405/06 was directed to immunoglobulins with certain stated features. The question to be answered was whether a skilled person would have found at the filing date in the application as filed a sufficiently clear and complete disclosure of the precise structure of such an immunoglobulin in order to be in a position to prepare it over the broad range of the claim. Although the claim was not limited to immunoglobulins obtained from camelids, the experimental part of the description as a whole and the corresponding figures dealt exclusively with camel immunoglobulins and the general part of the description did not contain a complete disclosure of any non-camelid immunoglobulin either. The requirements of Art. 83 EPC 1973 were thus not satisfied, as the skilled person would be left with the task and burden of finding out how the teaching relating to camelid immunoglobulins could be extended to products of different origins (e.g. human immunoglobulins) falling within the broad area of the claim.

The application the subject of T 433/07 concerned broadly reactive opsonic antibodies that react with common staphylococcal antigens. The board held that the invention was insufficiently disclosed; the application did not disclose either any serotype cross reactive monoclonal antibody or the isolation of an antigen associated with the serotype cross protective response required by the claim. A European patent application containing a claim referring to a method of production had to provide the skilled person with the means to produce the desired product. If this was not the case, this shortcoming could not be overcome by telling him exactly how the desired product had to look and which screening criteria had to be applied to find it.

In T 617/07 the claim at issue concerned monoclonal antibodies and synthetic and biotechnological derivatives thereof defined by structural and functional features. The board found that, given his common general knowledge, the skilled person would be able, in a possibly time-consuming but straightforward manner, to provide antibody variants having the functional requirements indicated in the claim. There was no doubt that the structural definition in the claim included antibodies that did not have the desired function but, when attempting to rework the invention the skilled person would on the basis of his knowledge be able to avoid non-functional variants. Therefore, because the skilled person knew how to achieve antibodies with the desired function on the basis of a particular known antibody, he was not in the situation of having to sort out non-functional variants in a burdensome manner.

In T 386/08 the patent concerned humanised antibodies with framework sequences. It disclosed not only one, but many examples. The board pointed out that the concept of sufficiency of disclosure over the whole scope of the claim did not mean that, for a disclosure to be considered as sufficient, it had to be demonstrated that each and every conceivable embodiment of a claim could be obtained; see G 1/03 (OJ 2004, 413). There may be situations where the specification contains sufficient information on the relevant criteria for finding appropriate alternatives ("variants") over the claimed range with reasonable effort. Under these circumstances the non-availability of certain variants encompassed by the claim at the priority date is considered immaterial for the sufficiency of disclosure. For an example where this was not so, see T 601/05 date: 2009-12-02. The current situation however was different in that the patent described quite a number of appropriate alternatives and in that the allegedly non-obtainable variants were "hypothetical" variants. The requirements of Art. 83 EPC were fulfilled.

Art. 83 EPC was not complied with in T 941/16 (anti-PSMA antibody). The board decided that, in the absence of any examples of a claimed antibody/fragment, the general information in the patent application and the common general knowledge, taken together, could not be considered to provide the information necessary to allow the skilled person to reliably obtain substantially all of the claimed antibodies/fragments fulfilling the functional requirements of the claim. For particular combinations of complementarity-determining regions (CDRs) it was not credible that a humanised antibody/fragment with the properties defined in claim 1 would be obtained. Readily performing the invention across the entire scope of the claim placed an undue burden on the skilled person. Lastly, the board, with reference to G 1/03 (OJ 2004, 413, point 2.5.2 of the Reasons), dealt with the argument made by the appellant (applicant) that patent applications in the field of biochemistry should not be treated worse than those in the other fields of classical chemistry (presence of non-working embodiments in a generic chemical formula).

The March 2022 version of the Guidelines includes a new section on antibodies since 2021 (see G‑II, 5.6). As regards claims directed to antibodies defined by functional features (i.e. by their ability to perform a certain function), they state in G‑II, 5.6.1.3: "If an antibody is defined exclusively by functional properties, it has to be carefully assessed whether the application provides an enabling disclosure across the whole scope claimed". As to the related case law, the boards held Art. 83 EPC not to be met in the following decisions: T 1466/05, T 601/05 date: 2009-12-02, T 1389/13. For examples of cases in which sufficient disclosure was established, see T 2045/09 and T 845/19 (antibody defined, after limitation, by structural and functional features).

For another decision concerning antibodies, see T 32/17 (definition of an antibody by reference to a deposited hybridoma – R. 31 EPC).

Whether opponents can cite post-published documents

In T 1872/16 (claim 1 was drafted in the form of a purpose-limited product claim pursuant to Art. 54(5) EPC) the suitability of an IL-13 antibody as defined in the claim for the treatment of specific forms of asthma had to be assessed. The application did not contain any experiments testing the suitability of the antibodies and did not disclose a link between IL-13 and the specific forms of asthma recited in the claim. The appellant (patent proprietor) disputed that the respondents-opponents could use post-published documents (i.e. D23, post-published clinical trial) to refute the suitability of a claimed compound for a claimed therapeutic application, submitting that only documents available at the effective date of the patent could be taken into account. The board explained that the standard established in the case law was that serious doubts had to be substantiated by verifiable facts. The opponents were free to use whatever evidence they chose to substantiate those serious doubts. This also applied to the date on which the evidence was generated. There might be cases where the serious doubts could only be properly substantiated by facts which were obtained after the effective date of the patent (see T 219/01 in relation to a medical use claim and lack of sufficient disclosure on the basis of post-published clinical trial). The respondents could therefore base their arguments on document D23. In the board's view, with the patent not containing any examples of antibodies which had been shown to be suitable for treating severe asthma, it was sufficient for the respondents to show one embodiment which was not suitable. On the basis of D23 the skilled person would have had serious doubts as to the suitability of the antibody for treating severe asthma. The requirements of Art. 83 EPC were not met.