T 1047/12 (RNA interference mediators/WHITEHEAD INSTITUTE) 01-03-2018

Reasons for the Decision

Article 123(2) EPC - added matter

1. In the decision under appeal, the opposition division found that the subject-matter of the amended claims according to the main request does not extend beyond the content of the application as filed. These findings were contested by the appellant only insofar as they related to amended claim 3, in particular as regards the features "double stranded RNA of from 21 to 23 nucleotides in length" and "corresponding to a sequence of the gene" (see section XI above).

2. Amended claim 3 is derived from claim 17 of the application as filed, which is directed to a method of mediating RNA interference of mRNA of a gene in a cell (or organism) by (a) introducing RNA from about 21 to about 23 nucleotides which targets the mRNA of the gene for degradation into the cell (or organism), and (b) maintaining that cell (or organism) under conditions under which degradation of the mRNA occurs. While claim 17 of the application as filed does not specify that the introduced RNA is double-stranded, it is stated on page 2, lines 22 to 24 of the application as filed that:

"As used herein, the terms RNA, RNA molecule(s), RNA segment(s) and RNA fragment(s) are used interchangeably to refer to RNA that mediates RNA interference. These terms include double-stranded RNA, single-stranded RNA,..." (emphasis added by the board).

3. The wording "As used herein" is often found in patent documents with the meaning "as used in this application/patent". Accordingly, a person skilled in the art reading the passage of the application as filed quoted above understands that the definition in lines 22 to 24 applies not only to the isolated RNA molecules described in lines 16 to 22 of the same page, but to any RNA mentioned in connection with other aspects of the disclosed invention, including a method of mediating RNA interference as defined in claim 17 and disclosed on page 4, lines 14 to 20 of the application. Contrary to the appellant's view, the fact that the passages on page 2, lines 30 and 31 and page 3, lines 8 to 10 of the application as filed refer to, respectively, "RNA molecules of the present invention" and "RNA molecules of about 21 to about 23 nucleotides" without specifying that these molecules are double-stranded, is not in contradiction with the previous definition of the term RNA molecule as including, inter alia, dsRNA.

4. As regards the feature "corresponding to a sequence of the gene", the board concurs with the opposition division's view that a verbatim basis is found in the passage on page 16, lines 25 and 26 of the application as filed (see section 5.5.2 of the decision under appeal). The passage in question does not refer exclusively to the precursor dsRNA, but rather to any dsRNA that can be used in the invention, including the 21 to 23 nt dsRNA. This is apparent from the fact that dsRNA of 21 or 22 base pairs is mentioned in the same paragraph (see lines 28 and 31, respectively), and that dsRNA of this length is clearly disclosed in the application in connection with a method for mediating RNA interference (see, e.g., page 17, lines 1 to 3).

5. For the sake of completeness, the board observes that it can be derived from the statements on page 16, lines 25 to 31 read in connection with those on page 13, lines 24 to 28, and page 3, lines 20 to 23 of the application as filed, that the dsRNA may be complementary to mammalian cellular mRNA or viral mRNA. Hence, also the findings in the decision under appeal concerning claim 13 are considered to be correct.

6. For these reasons, the appellant's objections to the findings on Article 123(2) EPC in the decision under appeal fail to convince the board.

Article 123(3) EPC - extension of the scope of protection

7. In the decision under appeal, the opposition division found that the amendments introduced into claims 9, 10, 12 and 13 did not result in the protection conferred by the patent as granted being extended (see section 4.3 of the decision). This finding has been contested by the appellant.

8. Claim 14 of the patent as granted, from which present claim 9 is derived, does not specify whether the dsRNA comprising a terminal 3' hydroxyl group is the input (i.e. precursor) dsRNA specified in claim 1, step (a), or the 21 to 23 nt dsRNA produced by the method of claim 1 and used in the method of claim 3. As far as claim 14 of the patent as granted depends on claim 4 (or claims 5, 6, 8 and 9 referring to claim 4), it is clear that only the 21-23 nt dsRNA can be meant, as this is the sole dsRNA species mentioned in those claims. In contrast, as far as claim 14 of the patent as granted depends on claims 1 to 3, it must be interpreted as referring to either the input dsRNA or the produced dsRNA of from 21 to 23 nucleotides in length, as both are mentioned in claims 1 to 3. The same applies, mutatis mutandis, to amended claims 10, 12 and 13, which are derived from, respectively, claims 15, 17 and 18 of the patent as granted.

9. By the amendment introduced into the present claims 9, 10, 12 and 13, the double stranded RNA is defined as having from 21 to 23 nucleotides in length. Since this is, contrary to the appellant's view, in fact a limitation compared to claim 14 as granted, in which the input dsRNA was also included, the amendment does not result in an extension of the scope of protection conferred by the claims of the patent as granted from which they are derived. Therefore, the objection that the amendment contravenes Article 123(3) EPC cannot be accepted.

Article 84 EPC - clarity

10. The appellant contested the opposition division's adverse findings on an alleged inconsistency between the passage on column 2, lines 5 to 8 of the adapted description and the amended claims (see section 11.1 of the decision under appeal). The board shares the opposition division's view that there is no such inconsistency, in particular as regards claim 3. It should be noted that the passage indicated by the appellant relates to the small dsRNAs resulting from the processing of the input dsRNA, rather than to the dsRNA used in the method of claim 3. In any case, since the alleged non-compliance with Article 84 EPC does not arise from the amendments introduced into claim 3, it does not need to be considered (see decision G 3/14, OJ EPO 2015, 102, Order).

Article 83 EPC - sufficiency of disclosure

11. While the appellant did not contest the findings in the decision under appeal concerning Article 83 EPC (see section 10 of the decision), it raised an objection to claim 3 under Article 83 EPC relying on document (6) as evidence that a 49 nt dsRNA incubated with the same Drosophila soluble extract used in the examples of the patent in suit is not effective in mediating RNA interference.

12. The evidence on which the appellant relied does not support its objection. Claim 3 requires that the dsRNA introduced into the cell is of from 21 to 23 nucleotides in length. Since a dsRNA of 49 nt in length as used in the experiment described in document (6) is clearly not within this range, the fact that such a dsRNA does not mediate RNA interference cannot be accepted as evidence that a person skilled in the art cannot carry out a method of mediating RNA interference according to the invention as defined in claim 3. Hence, the appellant's argument fails.

13. The appellant's further contention that the patent does not disclose the mechanism underlying RNA interference mediated by 21 to 23 nt dsRNA also fails, because there is no requirement under Article 83 EPC that the mechanism underlying an invention must be disclosed in the application as filed. As regards the objection that, at the filing date, the inventors were not in possession of the technical teaching of the claims, the appellant, except for pointing to paragraph 13 of the reasons of decision T 609/02 of 27 October 2004, did not put forward any arguments or evidence in this respect. The circumstances underlying decision T 609/02 (supra) differed substantially from those in the present case, because in that case the patent specification provided no evidence at all relating to the claimed invention, but only a vague indication of a possible medical use for a chemical compound yet to be identified. Hence, the ratio decidendi of T 609/02 (supra) is, in the board's view, not applicable to the present case.

14. In view of the evidence and arguments brought forward in appeal proceedings, the board has no doubts that the information provided in the application - supplemented by the common general knowledge in the field - enabled the skilled person to carry out the invention, without applying inventive skills or being confronted with an undue burden of experimentation. Hence, the objection of lack of sufficient disclosure is not justified.

Article 87 EPC - priority

15. The findings in the decision under appeal on Article 87 EPC in respect of claim 3 were contested by the appellant by referring to the arguments it put forward in connection with Articles 123(2) and 83 EPC.

16. Claim 16 and the passages on page 2, lines 5 to 7; and page 3, lines 14 to 19 of the first priority application are literally identical to claim 17 and the passages of the application as filed which are regarded as basis for the feature "double stranded RNA of from 21 to 23 nucleotides in length" (see paragraphs 2 and 3 above in connection with Article 123(2) EPC). Moreover, the passage from line 21 on page 11 to line 2 on page 12 of the priority document is identical to that on page 16 of the application as filed, from which the feature "corresponding to a sequence of the gene" can be derived (see paragraph 4 above).

17. As regards the appellant's allegation that a method as claimed in present claim 3 is not sufficiently disclosed in the priority document, the board refers to the findings in connection with Article 83 EPC in paragraphs 12 to 14 above. Contrary to appellant's view, the fact that the earlier application does not include experimental evidence corresponding to Example 5 of the application as filed, cannot be considered to be prejudicial to the right to priority claimed for the patent as amended. In order for a right to priority to be valid, it is not required that the earlier application provides experimental evidence that the disclosed invention in fact works (see decision T 903/05 of 30 August 2007, paragraphs 8 to 11 of the reasons).

18. For these reasons, the appellant's argument that the priority of the earlier application cannot be validly claimed for the method of claim 3 fails. Hence, document (23) constitutes prior art under Article 54(3) EPC 1973 which is relevant to the assessment of novelty of the claimed method, but cannot be considered for assessing whether the claimed method involves an inventive step.

Article 54 EPC - novelty

19. The appellant contested the findings in the decision under appeal as regards Article 54 EPC only as far as they concerned the novelty of claim 3 in view of either document (23) or document (27) (see section 8.5.2 of the decision).

20. Claim 3 defines an in vitro method of mediating RNA interference of mRNA in a cell. The mediation of RNA interference of mRNA in a cell is thus a technical feature of the claimed method (see decision G 6/88, OJ EPO 1990, 114, Order).

Document (23)

21. Document (23) describes a method of inhibiting the expression of a target gene by introducing into a cell a double stranded RNA molecule, one strand being complementary to at least a portion of the target gene over a stretch of no more than 49 consecutive nucleotides. In Example 2, the YFP gene encoding yellow fluorescent protein and a dsRNA molecule are microinjected simultaneously into the cell nucleus of murine fibroblasts. After injection of either a dsRNA homologous to the YFP gene over a length of 315 bp (see page 17, lines 25 to 28 and SEQ ID NO: 5 in the Sequence Listing), or a dsRNA of 21 bp in length corresponding to a sequence of the YFP gene, in which the two strands of the dsRNA are linked to each other via a C18 linker (L-dsRNA; see page 18, lines 13 to 15), YFP fluorescence could not be detected (see Figures 4c and 4e, and the passage on page 20, lines 12 and 13, and 15 to 17, respectively). The authors then conclude:

"Dieses Ergebnis belegt, dass auch kürzere dsRNAs zur spezifischen Inhibition der Genexpression bei Säugern verwendet werden können, wenn die Doppelstränge durch chemische Verknüpfung der Einzelstränge stabilisiert werden." (page 20, lines 17 to 21)

[This result shows that shorter dsRNAs can be used to specifically inhibit mammalian gene expression, if the double strands are stabilized by chemically linking the single strands] (translation by the board)

22. The board shares the opposition division's view that document (23) does not disclose or even suggest - let alone provide any evidence - that the double stranded RNA of 21 nt in length having the two strands linked via a C18 linker (L-dsRNA) targets the YFP mRNA for degradation. In fact, the passage quoted above mentions only inhibition of gene expression, and the fact that the L-dsRNA is injected into the nucleus casts doubts as to whether the L-dsRNA could possibly mediate degradation of the YFP mRNA which is expected to be in the cytoplasm. Therefore, the board concurs with the opposition division that it cannot be established beyond reasonable doubt from the information provided in document (23) that the reported lack of YFP fluorescence is due to the degradation of the YFP mRNA by the mechanism of RNA interference, rather than to a different silencing mechanism. Thus, the content of document (23) does not anticipate the subject-matter of claim 3.

Document (27)

23. Neither a dsRNA molecule of from 21 to 23 nucleotides in length, nor a method in which RNA interference is mediated by such a molecule can be derived, directly and unambiguously, from document (27). The oligonucleotides described in document (27) are proposed for use as antisense agents (see, e.g., page 1, lines 7 to 9, and page 5, lines 2 to 4), the double stranded region having the function of stabilizing the molecule and making it more resistant to nucleolytic degradation (see sentence bridging pages 8 and 9). Hence, the finding in the decision under appeal that document (27) is not prejudicial to the novelty of the method of claim 3 is considered to be correct.

Article 56 EPC - inventive step

24. In the decision under appeal (see section 9.2.4), the subject-matter of claims 1 and 3 (as well as that of the remaining claims which either depend on or refer to claim 1 or 3) was found to involve an inventive step within the meaning of Article 56 EPC. These findings were contested by the appellant only as far as they concerned claim 3.

25. The appellant relied on document (24) as the closest state of the art. This document describes methods of inhibiting the expression of a target gene by introducing into a cell an RNA molecule comprising a double stranded structure with a nucleotide sequence which is identical to a portion of the target gene. It is stated on page 11, lines 27 and 28 that the length of the identical nucleotide sequences may be at least 25, 50, 100, 200, 300 or 400 bases. It should be noted that these numbers characterize the length of the nucleotide sequence identical to the target gene, rather than the length of the RNA itself which may, in principle, be longer.

26. It is undisputed that the method described in document (24) differs from the method of present claim 3 in that the latter comprises introducing into the cell a dsRNA of from 21 to 23 nucleotides in length which mediates RNA interference.

27. The decision under appeal is silent about the objective technical problem to be solved starting from document (24) as the closest state of the art. According to the appellant, there are no advantageous technical effects linked to the use of a dsRNA of from 21 to 23 nt in length and, consequently, the problem to be solved can only be the provision of an alternative method of inducing RNA interference. This was disputed by the respondents which, at the oral proceedings, contended that the problem to be solved was the provision of a method for mediating RNA interference that does not provoke an interferon response in mammals.

28. Even if the board were to accept the problem to be solved as formulated by the appellant, the arguments and evidence on which it relied fail to convince the board that, at the priority date, it was obvious to a person skilled in the art seeking an alternative to the method of inducing RNA interference described in document (24) to reduce the length of the dsRNA to, specifically, 21 to 23 nt. A person skilled in the art, starting from document (24), could have possibly tried to induce RNA interference using a 25 nt dsRNA - as suggested in this document -, but had neither the motivation to try shorter dsRNA molecules, in particular dsRNA molecules of from 21 to 23 nt in length, nor a reasonable expectation that these molecules may induce RNA interference. It should be noted that the dsRNA molecules used in the examples of document (24) are several hundreds of nucleotides in length.

29. Document (28), which the appellant regarded as a pointer towards the method of the present invention, describes methods for reducing the phenotypic expression of a nucleic acid sequence in eukaryotic cells, in particular plant cells by introducing into a cell chimeric genes encoding sense and antisense RNA molecules which are, respectively, homologous and complementary to at least part of the nucleotide sequence of interest. The passage on page 9 lines 11 to 29 on which the appellant relied, relates to a method in which the chimeric genes are transcribed into a sense and an antisense RNA molecule, each including at least 10 consecutive nucleotides and having between 75% and 100% sequence identity with the gene and the complement of the gene, respectively. The sense and antisense RNA molecules are capable of forming a double stranded, duplex RNA by base-pairing between the regions which are complementary.

30. A skilled person reading document (24) in combination with document (28) could, in principle, try to mediate RNA interference using a dsRNA of at least 10 nucleotides in length. However, there is no apparent reason why the skilled person would choose specifically a length of 21 to 23 nt, as neither document (24) nor document (28) give any hint that would motivate him/her to use a dsRNA of this length, let alone arouse a reasonable expectation of being able to induce RNA interference using such a dsRNA.

31. The appellant relied further on the teachings of document (24) combined with those of document (29). However, neither document (29) as a whole nor the passage quoted by the appellant in section 2.3.1 of its statement of grounds of appeal - which the board was unable to find in document (29) - contain any pointer to the specific solution proposed in claim 3.

32. As stated in paragraph 18 above, document (23), which constitutes prior art under Article 54(3) EPC 1973, cannot be considered for the assessment of inventive step. Thus, the appellant's line of argument relying on a combination of document (24) with document (23) cannot be accepted.

33. Summarising the above, the arguments put forward by the appellant in support of its objection that the method of claim 3 does not involve an inventive step, fail to convince the board.

Article 113(1) EPC - right to be heard

34. In its communication under Article 15(1) RPBA, the board expressed a provisional opinion on the issues to be discussed at the oral proceedings. The reasons given by the board in the present decision are essentially those given in the communication. The appellant neither replied in substance to the board's communication, nor attended the oral proceedings. Since the appellant had ample opportunity to make any submissions it wished in respect of the grounds and evidence on which the present decision is based, the provisions of Article 113(1) EPC are complied with.