T 1524/23 (Multivalent PCV2 composition/BOEHRINGER INGELHEIM) 11-09-2025

I. European patent 3 320 919, with the title "Multivalent PCV2 immunogenic compositions and methods of producing such compositions" was granted on application EP 17 208 901.3. This application was a divisional application of earlier (parent) application EP 06 848 471.6, which was filed as an international application, published as WO 2007/076520. European patent 1 968 630 was granted on said parent application, which was subject to both opposition and appeal proceedings, with the final outcome being decision T 860/21 by which the patent was revoked.

II. The patent in suit was opposed by two opponents and was revoked by the opposition division. An appeal was filed by the patent proprietor (appellant) against the opposition division's decision to revoke the patent. Opponent 1 and 2 replied to the appeal and are respondent I and II in the appeal proceedings.

III. In the decision under appeal, the opposition division considered objections under Article 83 EPC made by the respondents against the main request (filed on 24 September 2021) and held that the claimed invention was not disclosed in the application as filed in a manner sufficiently clear and complete for it to be carried out by the skilled person. This finding was held to apply equally to the subject-matter of auxiliary claim requests 1 to 22. The set of claims of auxiliary request 23, submitted during the oral proceedings before the opposition division, was not admitted into the proceedings. The opposition division also provided obiter dicta on Articles 123(2)/ 76(1) EPC, Article 54 and Article 56 EPC.

IV. With its statement of grounds of appeal, the appellant resubmitted sets of claims of a main request and of auxiliary requests 1 to 23, previously submitted in the proceedings before the opposition division, and the sets of claims of auxiliary requests 24 to 27 for the first time.

V. The appellant submitted a corrected set of claims of auxiliary request 10 with a letter dated 3 May 2024.

VI. With letters dated 11 March 2025 respondent I submitted further arguments. Respondent II submitted letters dated 13 June 2024, 1 August 2024 and 21 March 2025. containing further arguments.

VII. The board issued a communication pursuant to Article 15(1) RPBA inter alia setting out its preliminary construction of claim 1 of the main request according to which, the feature that one dose of the vaccine is to be administered intramuscularly to the subject and the feature that therapeutic effect is obtained by a single administration of the vaccine, means that the therapeutic effect defined in the claim is achieved with the administration of one dose of the combination vaccine. In other words, in a regimen falling within the ambit of the claim, the subjects (piglets) receive only one dose of the vaccine defined the claim. However, the wording of the claim did not exclude that other immunogens or immunogenic compositions which are not the "A multivalent combination vaccine" defined in the claim, can contribute to achieving the therapeutic aim defined in the claim. Moreover, the claim did not define the vaccination status of the subjects.

The communication went on to explain that the board was of the preliminary view that the subject-matter of claim 1 of the main request considered by the board in the parent case T 860/21 was encompassed by claim 1 of the main request and that in view of this it was inclined to hear the parties on inventive step at the oral proceedings, and decide on this issue first, under its power pursuant to Article 111(1) EPC. It further informed the parties that it was of the preliminary view that the same considerations on inventive step as those reached in case T 860/21 applied to the subject-matter of present claim 1.

VIII. The appellant and respondent I replied to the board's communication, with letters dated 8 August 2025 (appellant), 14 July 2025 and 3 September 2025 (respondent I).

IX. All parties submitted documents for the first time in the appeal proceedings.

X. Oral proceedings before the board were held as scheduled. During the oral proceedings, the appellant withdrew auxiliary requests 1 to 23. Auxiliary requests 24 to 27 became auxiliary requests 1 to 4. At the end of the oral proceedings, the Chairwoman announced the decision of the board.

XI. Claim 1 of the main request reads as follows:

"1. A multivalent combination vaccine for use in a method for

(i) the prevention of an infection with PCV2, or re-infection with PCV2 or

(ii) the reduction or elimination of clinical symptoms caused by PCV2

in a subject, wherein one dose of the vaccine is to be administered intramuscularly to the subject and wherein

(i) said prevention of an infection with PCV2, or re-infection with PCV2 or

(ii)said reduction or elimination of clinical symptoms caused by PCV2,

is obtained by a single administration of the vaccine,

and wherein the vaccine includes

- an antigenic composition obtainable by a method comprising:

i) preparing and recovering recombinant PCV2 ORF2 protein, and

ii) admixing this with a suitable adjuvant

and

- at least one immunogenic active component against another disease-causing organism in swine".

Auxiliary request 1 (submitted as auxiliary request 24 with the statement of grounds of appeal)

Claim 1 of auxiliary request 1 differs from claim 1 of the main request in that it includes the additional feature "and wherein said vaccine comprises 2 myg to 50 myg recombinant PCV2 ORF2 protein per dose".

Auxiliary requests 2 to 4 (submitted as auxiliary requests 25 to 27 with the statement of grounds of appeal)

Claim 1 of auxiliary request 2 differs from claim 1 of the main request in that it includes the additional feature "and wherein said vaccine comprises 4 myg to 16 myg recombinant PCV2 ORF2 protein per dose".

Claim 1 of auxiliary request 3 differs from claim 1 of the main request in that "subject" has been replaced by "pig or piglet" and in that it includes the additional features "wherein the administration of the combination vaccine is performed when the animals are 2 to 8 weeks of age,

and wherein said vaccine comprises 2 myg to 50 myg recombinant PCV2 ORF2 protein per dose".

Claim 1 of auxiliary request 4 differs from claim 1 of auxiliary request 3 in that the dose is "4 myg to 16 myg" instead of "2 myg to 50 myg".

XII. The following document is referred to in this decision.

D9: Blanchard P. et al., "Protection of swine against post-weaning multisystemic wasting syndrome (PMWS) by porcine circovirus type 2 (PCV2) proteins", Vaccine, 2003, 21, 4565-4575.

XIII. The appellant's submissions relevant to the decision are summarised as follows:

Main request - claim 1

Claim construction

The claim was a purpose-limited product claim and was directed to a multivalent combination vaccine comprising recombinant PCV2 ORF2 protein and at least one immunogenic active component against another swine pathogen, wherein the vaccine was administered in a single dose intramuscularly to confer protection against PCV2 infection or reduce/eliminate associated clinical symptoms. The claimed vaccine achieved protection against PCV2 infection in "one-shot". The subjects received no other treatment of PCV2 infection or of its symptoms.

The only therapeutic effects required by the claim were (i) the prevention of an infection with PCV2, or re-infection with PCV2 or (ii) the reduction or elimination of clinical symptoms caused by PCV2. No therapeutic efficacy against the "at least one immunogenic active component against another disease-causing organism in swine" (further immunogen) was required by the claim. It was sufficient that the further immunogen elicited an immune response.

Remittal (Article 111(1) EPC and Article 11 RPBA)

Remittal to the opposition division was appropriate to allow the case to be heard by two instances. The decision under appeal only dealt with some aspects under Article 83 EPC, while inventive step was not considered. Moreover, the objection of lack inventive step based on a claim construction now pursued by the respondents had been only one of many objections initially raised. It would have been in keeping with procedural economy to file auxiliary requests to take all such objections into account. Furthermore, it had only become clear that the board was unlikely to adopt the appellant's claim construction in relation to the 'one shot' feature as decisions in related cases were issued. In particular, the decision in the parent case, T 860/21 was the first case to deal with a combination vaccine. Although the board had adopted a similar claim construction in decision T 2410/19, the opposition division had in its obiter dictum expressed doubts that this construction would stand.

Thus, remittal was appropriate to allow the parties to put their arguments on inventive step to the opposition division in the light of decisions T 2410/19 and T 860/21. The findings in these decisions represented special reasons for remittal within the meaning of Article 11 RPBA.

Inventive step (Article 56 EPC)

None of the cited prior art documents disclosed or rendered obvious the claimed one-shot administration of a recombinant PCV2 ORF2 protein-based vaccine for achieving the recited medical effects.

D9 disclosed prime-boost vaccination regimens involving multiple administrations, including DNA priming and protein boosting, and did not suggest that a single administration of recombinant PCV2 ORF2 protein alone could confer protective immunity. The authors of D9 themselves had recommended further studies using prime-boost approaches.

The claimed invention provided a surprising technical effect, namely that a single administration of recombinant PCV2 ORF2 protein was sufficient to confer protective immunity against PCV2 infection. This was supported by experimental data in the patent (Examples 4 and 5), which showed efficacy across multiple clinical parameters. The prior art did not provide a reasonable expectation of success for achieving such an effect with a one-shot subunit vaccine.

Regarding the inclusion of a second immunogenic active component, such as PRRSV or M. hyo antigens, the prior art did not disclose or suggest that such components could be combined with PCV2 ORF2 protein in a single-dose vaccine without compromising efficacy.

Even when adopting the claim construction given in the board's communication under Article 15(1) RPBA, the claimed subject-matter still differed from that disclosed in D9 in the addition of the further antigen. Should the skilled person have considered including another antigen in a vaccination scheme disclosed in D9, there were three options of how the second antigen could be included in the vaccination regime disclosed in D9: i) together with the first injection (DNA), ii) together with the second injection (DNA), or iii) together with the third injection (protein subunit).

If anything, the skilled person would have added the further antigen to the first injection because this took place when the pigs were 25 days old, while the second injection and the third (protein) injection were administered at an age of 39 days. In general, it would be desirable to have any effect of the further component (even if not required in itself to lead to protection, but merely to aid in the generation of the immune response as a further immunogenic component) as early as possible. Thus, even if the skilled person had decided to include a further antigen, they would not have arrived at the claimed subject matter.

Respondent II had submitted that the skilled person would not have administered a PRRS vaccine along with the PCV DNA vaccine. This was not correct. Firstly, the second antigen in the claim was not limited to PRRS vaccines. Secondly, even D9 itself in trial 1 taught that DNA and protein vaccines can be administered at the same time, in form of the second and third shot two weeks after first DNA shot (point 2.4.1). There was no teaching in the art that suggested that DNA and protein vaccines cannot be administered together, whether they are mixed prior to administration or not.

Auxiliary requests 1 to 4

Admittance (Article 12(4) RPBA)

These auxiliary requests should be admitted because they met the requirements for admittance set out in Article 12(4) RPBA. They had been filed with the statement of grounds of appeal, which was the earliest suitable moment. Their filing was triggered inter alia by the fact that in decision T 2410/19 on a related case, a different claim interpretation on the "one shot" feature was adopted, compared to that in earlier decision T 1021/11. The decision under appeal did not deal with claim construction because it dealt only with an aspect of the requirements of Article 83 EPC which did not depend on claim construction. Moreover, in an obiter dictum the opposition division had indicated doubts about whether the claim construction in T 2410/19 would be followed.

Thus the auxiliary requests were filed at the earliest opportunity and the amendments made further supported inventive step even under the claim construction adopted T 2410/19 and T 860/21.

The amendments made were straightforward and overcame the respondents' inventive step objections even under the changed claim construction, while not adding any further complexity or raising new issues. The concept of a dose for the recombinant ORF2 protein was already present within the claim set of the main request. Auxiliary requests 1 to 4 merely restricted this feature in a more narrow way in the independent claims. The claims of these auxiliary requests recited a significantly smaller dose than that used in D9 and there was no indication or any teaching in D9 or in any other document cited by the respondents that a small dose as recited in the claims would be effective in a one dose vaccine as claimed. Reducing the dose in a vaccine could lead to a reduction of effects, and the present patent showed that the ORF2 protein was a stronger antigen than e.g. inactivated whole virus or isolated viral ORF2 antigen, see paragraph [0116] and example 4.

Accordingly, the claimed invention provided substantial benefits over D9, as it allowed vaccination with much lower amounts of protein, allowing e.g. for more economic vaccination schemes. Starting from D9, the skilled person had no teaching towards the claimed invention, and clearly had no reasonable expectation that a significantly lower dose could obtain the beneficial effects.

XIV. The respondents' submissions relevant to the decision are summarised as follows:

Main request - claim 1

Claim construction

Claim 1 was drafted in the format of a purpose-limited product claim under Article 54(5) EPC and, as such, had to be interpreted as open, in that it did not exclude the administration of other agents prior to or following the administration of the claimed multivalent combination vaccine. Nor did it exclude that the subjects (e.g. pigs) had previously received or would subsequently receive other treatments. The terms 'one dose' and 'single administration' were to be understood as applying solely to the administration of the claimed vaccine and did not preclude additional administrations of other substances.

This approach to claim construction had been applied by the boards in related cases, in particular in decisions T 2410/19 and T 860/21. In these cases, the board had held that the therapeutic effect recited in a purpose-limited product claim did not need to be achieved exclusively by the claimed product and that the claim format did not impose further restrictions on the treatment regimen or patient population.

Remittal (Article 111(1) EPC and Article 11 RPBA)

The case should not be remitted to the opposition division just because the board announced its intention to deal with inventive step before sufficiency of disclosure. There were several reasons for not remitting the case to the opposition division, including the age of the case and the need for legal certainty. Remitting the case would only prolong uncertainty. Moreover, the claim construction now adopted by the board had been put forward by the respondents since the very beginning of the opposition and was no surprise to the appellant. The appellant had presented its case based on a preferred claim construction without preparing fall back positions in case this was not adopted. Furthermore, there were no special reasons for remittal under Article 11 RPBA, for instance there had been no deficiencies in the proceedings before the opposition division. In any case, parties did not have a right to have all issues in a case dealt with by the opposition division and the board of appeal.

Inventive step (Article 56 EPC)

Regarding inventive step, the preliminary conclusion set out in the board's communication pursuant to Article 15(1) RPBA was correct. The findings reached in case T 860/21 applied equally to the subject-matter of present claim 1, thus the subject-matter of claim 1 lacked an inventive step over several prior art documents, particularly D9 (trial 1).

D9 in trial 1 disclosed a single administration of PCV2 protein in combination with prior or simultaneous DNA injections. The only distinguishing feature of claim 1 was the presence of a second antigen. The patent did not disclose any unexpected technical effect of administering an additional immunogenic active component against another disease causing organism in swine in the context of vaccination against PCV2. Thus, the objective technical problem was merely to provide an alternative vaccine for the same purpose as the one disclosed in D9, i.e. preventing or treating PCV2 infection in piglets.

For the skilled person, the combination of known antigens in a multivalent vaccine was routine and motivated by known advantages such as cost reduction, ease of administration and animal welfare. The purpose of adding one or more further immunogenic active components against another disease-causing organism in swine would normally be to provide protection against the further disease-causing organism(s). It was completely obvious to the skilled person to want to produce combination vaccines for the sake of convenience and no unexpected technical effect of doing so could be derived from the patent.

The appellant had further argued that the claimed invention was not obvious starting from D9, trial 1, on the basis that the skilled person would have combined the second antigen, namely PRRS, with the DNA injection of D9, trial 1, rather than with the PCV2 protein injection. According to the appellant, this would have led the skilled person away from the claimed subject-matter.

However, the skilled person would have been motivated to combine the second antigen with the PCV2 protein, rather than with the DNA encoding ORF2, for several reasons:

a) From a technical perspective, the skilled person would have considered the stability and compatibility of the components, which would have favoured combining the second antigen with the protein rather than with the DNA.

b) In terms of timing, the skilled person would have been inclined to administer additional immunogen, such as Mycoplasma hyopneumoniae (Mhyo), PRRS, or Lawsonia intracellularis, at the time of the protein administration in trial 1 of D9, which occurred at approximately 5.5 weeks of age. This timing corresponded well with standard vaccination schedules for these pathogens, typically administered between 4 and 7 weeks of age.

c) In any case, the claimed multivalent combination vaccine did not exhibit any surprising technical effect compared to the use of two separate monovalent vaccines. In the absence of a demonstrated synergistic effect or other unexpected benefit arising from the combination of the two immunogens in a single formulation, the claimed subject-matter represented a mere obvious alternative lacking inventive step.

Auxiliary requests 1 to 4

Admittance (Article 12(4) RPBA)

Auxiliary requests 1 to 4 had been filed too late in the proceedings to be admitted. They had not been submitted during the proceedings before the opposition division despite the fact that the objections they aimed to address (particularly those under Article 56 EPC) had been raised by the respondents from the beginning of the opposition proceedings. The 'open' claim construction had also been presented since the beginning of the opposition proceedings. Admitting these claim requests would disadvantage the respondents, who had not had the opportunity to respond to these new claim sets during the opposition proceedings. The appeal proceedings were in principle a review process, and admittance of the auxiliary requests would not be in keeping with this but instead restart the opposition proceedings with claim sets directed to an invention whose subject-matter was not in the focus of the opposition proceedings until now.

In any case, the appellant had had ample opportunity to respond to the respondents' objections earlier, including after receiving the summons to oral proceedings and the preliminary opinion of the opposition division.

These claim requests were therefore not to be admitted under Article 12(4) RPBA. They moreover lacked prima facie allowability under multiple EPC provisions. In particular, they did not contribute to inventive step, the claimed invention did not meet the requirements of Article 83 EPC and the claimed subject-matter contravened Article 123(2) EPC.

In relation to the late filing of these claim requests, the appellant had not explained why these requests were not filed earlier or how they overcame the objections raised.

Relevant requests of the parties

XV. The appellant requested that the decision under appeal be set aside and that the patent be maintained in amended form based on the set of claims of the main request as filed on 24 September 2021, or alternatively, of auxiliary requests 1 to 4, filed as auxiliary requests 24 to 27 with the statement of grounds of appeal.

It further requested that:

- in case the board considered that any claim request meets the requirements of Article 83 EPC, the case be remitted to the opposition division for further prosecution.

XVI. Both respondents requested that the appeal be dismissed and that none of auxiliary requests 1 to 4 (filed as auxiliary requests 24 to 27 with the statement of grounds of appeal) be admitted into the proceedings.

XVII. The parties also maintained requests for the admittance and non-admittance of various documents and lines of argument, which are not relevant to this decision. They are recorded in the minutes of the oral proceedings before the board. In relation to the issue of inventive step, the board took into account the appellant's substantive submissions and evidence relied upon irrespective of whether the admittance of these submissions was in dispute.