T 1987/16 (Controlling gene expression/BASF) 17-06-2020

Summary of Facts and Submissions

I. The appeal lodged by the patent proprietor ("appellant") lies from the opposition division's interlocutory decision concerning the maintenance of European patent No. 1 874 936 in amended form on the basis of auxiliary request 3. The patent is entitled "Improved methods controlling gene expression".

II. An opposition was filed against the patent. The patent was opposed under Article 100(a) EPC on the ground of lack of inventive step (Article 56 EPC) and under Article 100(b) and (c) EPC.

III. In the decision under appeal the opposition division decided that claims 1 and 2 of the main request and claim 1 of auxiliary requests 1 and 2 contravened the requirements of Article 123(2) EPC. By contrast, it decided that the subject-matter of the claims of auxiliary request 3 complied with the requirements of Article 123(2) EPC, was sufficiently disclosed (Article 83 EPC) and involved an inventive step (Article 56 EPC).

IV. With the statement setting out the grounds of appeal the appellant requested, as a main request, that the patent be maintained as granted. In the alternative, they requested that the patent be maintained on the basis of the sets of claims of auxiliary requests 1 and 2, which are identical, respectively, to auxiliary requests 1 and 2 on which the decision under appeal was based. A further request, namely "to remit the case to the Opposition Division for further examination under Art. 56 and 83 EPC", was later withdrawn.

V. Claims 1 and 2 of the main request (claims as granted) read:

"1. A method to reduce or eliminate leakiness of transgene expression in monocotyledonous plants said method comprising the steps of:

a) providing an expression construct comprising a promoter sequence functional in said plant or plant tissue and functionally linked thereto said transgene to transcribe a chimeric RNA sequence, said transgene comprising

i) an open reading frame encoding a protein of interest that is capable to confer a preferred phenotype or beneficial effect to said plant, and

ii) a sequence substantially complementary to an endogenous microRNA sequence, wherein said endogenous microRNA is expressed in tissues, at times, and/or under environmental conditions, where expression of the chimeric RNA sequence is not desired, and wherein said endogenous microRNA is not or substantially less expressed in tissues, at times, and/or under environmental conditions, where expression of the chimeric RNA sequence is desired, wherein sequence i) and sequence ii) are heterologous to each other, and

b) introducing said expression construct into a plant, wherein the sequence being substantially complementary to the microRNA is positioned in a location of said transgene corresponding to the 5'-untranslated region or the 3'-untranslated region of said transgene and wherein expression of said chimeric RNA is suppressed in tissues, at times, and/or under environmental conditions where said endogenous miRNA is expressed.

2. The method of claim 1, wherein said promoter is selected from the group consisting of constitutive promoters, tissue-specific or tissue-preferential promoters, and inducible promoters."

VI. The opponent did not appeal against the opposition division's decision and is thus respondent and party as of right.

VII. The respondent did not reply to the appeal.

VIII. The board summoned the parties to oral proceedings as requested and informed them, in a communication pursuant to Article 15(1) RPBA, of its preliminary opinion that the subject-matter of the European patent (main request) did not extend beyond the content of the application as filed (points 11 to 13). The board also noted that further objections to the claims of the main request did not need considering as the respondent had not replied to the appeal, and that it saw no reason to examine the further grounds for opposition of its own motion. The board informed the parties that it intended to grant the appellant's request to maintain the patent as granted.

IX. The respondent did not reply to the board's communication.

X. Oral proceedings were cancelled.

XI. The appellant's arguments submitted in writing and as far as relevant to the present decision may be summarised as follows:

Main request (claims as granted)

Extension beyond the content of the application as filed (Article 100(c) EPC)

Page 6, lines 14 and 15 of the application as filed (hereinafter the "application") disclosed an indication that there was a need for improvement of tissue-specificity or the control of promoter leakiness. The next sentence in lines 16 and 17 explicitly stated that the invention provided such means and methods without being limited to a certain type of promoter such as a tissue-specific promoter. Thus, the skilled person could directly and unambiguously derive from the application that the promoter to be used in the method for controlling leakiness could be any type of promoter.

To fulfil the requirements of Article 123(2) EPC, it was not necessary for the description to contain a passage discussing leakiness in the context of e.g. constitutive promoters, as stated in the opposition division's decision, because claim 1 as granted referred to promoters in general, not to a specific promoter (such as a tissue-specific promoter). Furthermore, the application defined the term "promoter" as a constitutive, tissue-specific, tissue-preferential or inducible promoter (see for example pages 27 and 28). This definition made it clear that the promoter referred to on page 6, lines 14 and 15 could be a promoter as set forth in claim 2 as granted.

Furthermore, page 38, lines 24 to 29 of the application disclosed that the nucleotide sequence for expression of the chimeric RNA could be combined with a number of promoters. Constitutive, inducible and tissue-preferential promoters were explicitly mentioned.

In the decision under appeal, the opposition division was wrong to find that the skilled person reading the application would conclude that leakiness was not a property of constitutive promoters. Taking into account the application as a whole, the skilled person would also have derived that the leakiness of constitutive promoters could be reduced; see for example Figure 4.

The table on page 143 of the application dealt with "Vectors and miRNA tags used for leakiness control" (see title of the table, emphasis added). Six different vector constructs were disclosed, all of them using the ScBV promoter, which conferred constitutive expression.

Further examples in the application for leakiness control of constitutive promoters were e.g. the AHAS gene under control of the Ubi promoter (see page 134, lines 23 to 37) and the constitutive expression of the Bt protein (see page 134, lines 17 to 21).