Thursday, 17 December 2009

T 725/05 – A Fateful Alternative

The present decision, already discussed in my preceding post, also contains a textbook example of how an amendment of the description can lead to an undue extension of the claimed subject-matter.

Besides a few minor amendments, which do not have to be considered in the context of A 76(1), the present divisional application as originally filed is distinguished from the parent application as originally filed by the insertion of two paragraphs.

Firstly, by referring to the disclosure in document D4, the original definition of complementary determining regions (CDRs) according to Kabat is described. Then it is stated that “more recently Chotia et al have given an alternate definition of the hypervariable regions or CDRs …”. The term “Chotia CDR” is then introduced and it is mentioned that for five of the six CDRs the “Chotia CDRs” are subsets of the Kabat CDRs. The single exception to this is the first CDR on the heavy chain (CDR H1) where the “Chotia CDR” contains amino acids 26 to 30 that are not part of the Kabat CDR.

The description goes on to discuss prior art document D3. It is said that therein a humanised antibody was disclosed wherein the Kabat CDRs were transferred from a donor (a mouse) to a predetermined human framework. Additionally, in order to improve the humanised antibody’s binding affinity and its ability to lyse target cells, two mouse amino acids were transferred which were positioned in “Chotia CDR H1”, but no other mouse amino acids. [15]

The [patentee] argues, that this part of the description, not contained in the parent application as originally filed, has been introduced in the section headed “Background of the Invention”, which was immediately followed by the section “Summary of the Invention”. It referred therefore merely to the recognition of a disclosure in the state of the art, which according to the case law of the Boards of Appeal, e.g. decision T 11/82, cannot be regarded as added subject-matter. It was evident that the content of the introduced paragraphs had no “dictionary function” in the sense that a patent, being a legal document, may define technical terms and determine how a skilled person has to interpret a specific term when used in the description or in the claims. Rather the skilled reader, knowing from document D5 that Chotia gave no separate CDR definition, would have disregarded their teaching as being misleading and as having no impact on the definition of the term CDR.

[…] The Appellant argued further, that the skilled reader after having reached the conclusion to disregard the teaching on page 4, line 9 to page 5, line 7 of the divisional application as originally filed, as being confusing and misleading, would have found evidence that the term CDRs had to be understood as referring to Kabat CDR’s at several passages of the application as filed. [16]

Opponent 03 considered the introduced paragraphs of the description to disclose an alternate definition of CDRs. Opponent 05 argued that the newly introduced passages of the description, although not explicitly stating it, have to be interpreted as referring to a definition of CDRs as meaning Kabat together with Chotia. [17]

[…] Decision T 11/82 [22] states that the mere addition to the description of a reference to prior art cannot reasonably be interpreted as the addition of “subject-matter” contrary to A 123(2). Nor is it inevitable that the addition of a discussion of the advantages of the invention with reference to such prior art would constitute a contravention of that Article. Whether it did so would clearly depend on the actual language used and the circumstances of the case. [19]

However, the discussion of D5 [in] the divisional application as filed is not “the mere addition to the description of a reference to prior art”. In fact, by stating that it gives an alternate definition of the hypervariable regions or CDRs, it goes far beyond the disclosure in said document which expressly mentions […] that it refers to loops, whose “limits are somewhat different from those of the complementarity determining regions defined by Kabat”. By immediately thereafter introducing the term “Chotia CDR” as being an alternate definition for “Kabat CDR”, this new part of the description provides the public with the instruction that the term “CDR” may be Kabat CDR or “Chotia CDR”. […] As decision T 11/82 does not refer to a situation where the analyses and discussion of a prior art document goes [sic] far beyond the actual disclosure in said document, it is not relevant for the present case. [20]

Although the added parts of the description have been introduced in the section “Background of the Invention” their content is considered by the Board to have an essential impact on the skilled reader’s interpretation of the term CDR in the following parts of the application. The reader is provided with the technical teaching that, besides the generally accepted definition of CDRs according to Kabat, there is another, alternate definition of this term according to Chotia. […] [21]

The Board sees no reason why the skilled reader should disregard the clear information conveyed by the disclosure of the divisional application as filed. [22]

The Appellant relied on paragraph [0040] of the patent as granted, which he considered to give a definition for CDRs and to be a basis for the assumption that the term CDRs in the application means Kabat CDRs only. This passage reads: “As used herein, the term "framework region" refers to those portions of immunoglobulin light and heavy chain variable regions that are relatively conserved (i.e., other than the CDRs) among different immunoglobulins in a single species, as defined by Kabat, et al., op. cit. As used herein a "human-like framework region" is a framework region that in each existing chain comprises at least about 70 or more amino acid residues, typically 75 or 85 or more residues, identical to those in a human immunoglobulin.” The first sentence of this passage states that, according to Kabat, framework regions, other than CDRs, are relatively conserved. Thus, the information given does not concern the actual extent of framework regions, by disclosing those amino acid residues that are part thereof, but concerns their degree of conservation. The second sentence defines the term “human like framework regions”. Therefore, this passage does not provide a definition of the term CDRs. [23]

The second paragraph referred to by the Appellant is paragraph [0046] of the patent as granted. This paragraph refers to document D15 and states that its disclosure is “excluded from coverage”. The Appellant seems to argue that a reference to this document which itself refers to CDRs as being Kabat CDRs has to be considered as a basis for finding that the same term when used in the present application also means Kabat CDRs only. The Board cannot agree. The acknowledgement of the disclosure in a prior art document is no basis for the allegation that a technical term defined in this document in a specific way has to be interpreted in an identical way in the present application, which on pages 3 and 4 contains an explicit statement that the term is defined in a different manner. [24]

[…] the Board reaches the decision that the application as originally filed refers to CDRs which are defined according to Kabat, or according to the alternate definition of Chotia. Since the parent application as originally filed does not refer to CDRs according to Chotia, the divisional application contains subject-matter going beyond the content of the earlier application as filed and does not meet the requirements of A 76(1). [25] 

To read the whole decision, click here.