T 0308/17 (Methods for refolding of recombinant antibodies/AMGEN) 11-09-2019

Summary of Facts and Submissions

I. In an interlocutory decision, the opposition division decided that European patent No. 1 805 320, entitled "Methods for refolding of recombinant antibodies", met the requirements of the EPC in amended form on the basis of the main request (Article 101(3)(a) EPC).

II. The patent was opposed by opponent 1 and opponent 2, under Article 100(a) EPC on the grounds of lack of novelty (Article 54 EPC) and lack of inventive step (Article 56 EPC) and under Article 100(b) and 100(c) EPC.

III. Appeals were filed against the opposition division's decision by opponent 1 (appellant I) and opponent 2 (appellant II). The patent proprietor is respondent to the appeals.

IV. In their statement of grounds of appeal, appellant I submitted arguments to the effect that the subject-matter of claim 1 of the main request did not meet the requirements of Articles 54, 56, 83 and 123(2) EPC.

V. In their statement of grounds of appeal, appellant II submitted arguments to the effect that the subject-matter of claims 1 and 20 to 22 of the main request did not meet the requirements of Article 123(2) EPC, that the invention of claims 1 to 22 did not meet the requirements of Article 83 EPC, that the subject-matter of claims 1 to 3, 6 to 8, 12, 13, 17 to 22 did not meet the requirements of Article 54 EPC and that the subject-matter of claims 1 to 16 and 18 to 22 did not meet the requirements of Article 56 EPC.

VI. With the reply to the appellants' statements of grounds of appeal, the respondent submitted a main request and auxiliary requests I to XVIII. The main request corresponded to the request considered allowable by the opposition division. Auxiliary requests I to XVIII were filed for the first time in the appeal proceedings.

VII. The board appointed oral proceedings as requested by the parties and subsequently issued a communication pursuant to Article 15(1) RPBA setting out its preliminary appreciation of substantive and legal matters concerning the appeal. In this communication, the parties were informed, inter alia, that the board was of the preliminary view "that the method disclosed in document D1 anticipates the subject-matter of claim 1 [of the main request and that] this objection would appear to hold for the subject-matter of claim 1 of auxiliary requests I to IX".

VIII. In response to the board's communication the respondent filed a written submission and additional auxiliary requests XIa, XIb, XIIa and XIIb.

IX. Claims 1, 6, 7, 12 and 13 of the main request read:

"1. A method of producing an IgG2 antibody or an IgG2 antibody fragment preparation enriched for one of several separate IgG2 forms comprising:

contacting an IgG2 antibody or an IgG2 antibody fragment that has been recombinantly produced by mammalian cells with a reduction/oxidation coupling reagent at a pH of 5 to 11;

wherein said IgG2 antibody or IgG2 antibody fragment elutes as several separate forms on RP-HPLC and said method decreases the number of forms eluting on RP-HPLC, or alters the relative distribution of said several separate forms on said RP-HPLC; further comprising contacting said IgG2 antibody with a chaotropic agent before, after or concurrently with said contacting with said reduction/oxidation coupling reagent.

6. The method of Claim 1, wherein the reduction/oxidation coupling reagent comprises cysteine/cystine.

7. The method of Claim 6, wherein the cysteine/cystine comprises from 0.1 mM to 10 mM cysteine.

2. The method of Claim 1, wherein said contacting produces a IgG2 antibody having at least a two-fold increase in its biological activity compared to the same IgG2 antibody that is not contacted.

13. The method of Claim 1, wherein the chaotropic agent is selected from the group consisting of: urea, arginine, SDS and guanidine hydrochloride."

X. Claim 1 of auxiliary requests I to VI is identical to claim 1 of the main request. Claim 1 of auxiliary requests VII to IX differs from claim 1 of the main request in that references to "an IgG to antibody fragment" are deleted and the phrase "at least" is inserted before the phrase "one of several separate IgG2 forms".

XI. Claim 1 of auxiliary request X has been amended to delete "or an IgG2 antibody fragment" throughout and to insert the words "at least" in front of the word "one" in the second line. Furthermore, the half sentence "wherein said recombinant IgG2 antibody is purified, or wherein said recombinant IgG2 antibody is partially purified prior to said contacting" has been added after the pH range. Finally, the half sentence "and further comprising isolating a fraction of the contacted IgG2 antibody having a desired refolded confirmation" has been added to the end of the claim.

XII. Claim 1 of auxiliary requests XI and XII is the same and reads:

"1. Use of a chaotropic agent in a method for producing an IgG2 antibody preparation enriched for at least one of several separate IgG2 forms comprising:

contacting an IgG2 antibody that has been recombinantly produced by mammalian cells with a reduction/oxidation coupling reagent at a pH of 5 to 11;

wherein said IgG2 antibody elutes as several separate forms on RP-HPLC and said method decreases the number of forms eluting on RP-HPLC, or alters the relative distribution of said several separate forms on said RP-HPLC; further comprising contacting said IgG2 antibody with said chaotropic agent before, after or concurrently with said contacting with said reduction/oxidation coupling reagent".

XIII. Claim 1 of auxiliary requests XIa and XIIa is the same and reads:

"Use of a chaotropic agent for enriching at least one of several separate IgG2 forms in an IgG2 antibody preparation, comprising:

contacting an IgG2 antibody that has been recombinantly produced by mammalian cells with a reduction/oxidation coupling reagent at a pH of 5 to 11;

further comprising contacting said IgG2 antibody with said chaotropic agent before, after or concurrently with said contacting with said reduction/oxidation coupling reagent;

wherein said IgG2 antibody elutes as several separate forms on RP-HPLC and said contacting decreases the number of forms eluting on RP-HPLC, or alters the relative distribution of said several separate forms on said RP-HPLC".

Claim 1 of auxiliary requests XIII and XIV is the same as claim 1 of auxiliary request VII except that it further incorporates the subject-matter of claim 12 of the main request.

Claim 1 of auxiliary requests XV and XVI is the same as claim 1 of auxiliary request VII except that it incorporates the additional feature "at a concentration of 0.1 M to 2 M" after the phrase "chaotropic agent".

Claim 1 of auxiliary requests XVII and XVIII is the same as claim 1 of auxiliary request VII except that it has the additional feature "wherein said chaotropic agent comprises 0.5M to 1.5M guanidine hydrochloride" added to the end of the claim.

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

D1: WO 03/002713

XV. Oral proceedings before the board were held on 11 September 2019. During the course of the proceedings, the respondent submitted a written objection according to Rule 106 EPC.

XVI. The wording of this objection was as follows:

"We are of the view that a fundamental violation of Art 113 EPC has occurred, in the meaning of Article 112a(2)(c) EPC due to the fact [sic] the Board of Appeal has not admitted auxiliary requests X, XIII to XVIII into the proceedings".

XVII. During the course of the oral proceedings, the respondent withdrew auxiliary requests XIb and XIIb and submitted auxiliary request XIX.

Claim 1 of auxiliary request XIX is the same as claim 1 of auxiliary request XI except that it includes the additional feature "wherein said contacting produces a [sic] IgG2 antibody having at least a two-fold increase in its biological activity compared to the same IgG2 antibody that is not contacted".

XVIII. At the end of the proceedings the Chair announced the decision of the board.

XIX. The arguments of appellant II regarding admissibility of auxiliary requests I to XVIII are summarised as follows:

Admissibility of auxiliary requests I to XVIII - Article 12(2), 12(4) and Article 13(1) RPBA

Auxiliary requests I to XVIII were filed for the first time in the appeal proceedings. They should not be admitted into the proceedings due to a lack of substantiation. The respondent had not explained why the auxiliary requests overcame the objections raised in the statement of grounds of appeal if the main request was held unallowable. In decision T 1732/10, the competent board held that "unsubstantiated requests normally become effective only at the date on which they are substantiated. Their filing in and of itself plays therefore no role [...] if, as in the present case, the requests are not self-explanatory" (see reasons 1.5)

Appeal proceedings were wholly separate and independent from the proceedings at first instance, their function being to give a judicial decision upon the correctness of the earlier decision taken by the opposition division. This was reflected in Article 12 RPBA.

Article 13 RPBA concerned amendments to a party's case after it had filed its grounds of appeal. Together, Articles 12 and 13 RPBA aimed at concentrating the parties' submissions at an early stage of the proceedings, to ensure that a case is as complete as possible when it is processed (Case Law of the Boards of Appeal, 8th edition 2016, IV.E.4.1.2).

The boards had frequently held that a statement of grounds, referring generally to submissions made at first instance cannot be considered sufficient for the purposes of Article 108, 3rd sentence, EPC. By analogy and for reasons of equity, reference to submissions made at first instance in the reply to the statement of grounds of appeal should generally not be considered as a proper substantiation of the respondent's requests.

Appellant II argued at the oral proceedings that it was not clear which objection(s) the changes made in claim 1 of auxiliary request X were supposed to overcome and that the respondent could not in appeal proceedings rely on an alleged substantiation given in the first instance proceedings.

XX. The appellants' arguments are further summarised as follows:

Admissibility of auxiliary requests XIa and XIIa - Article 13(1) RPBA

These requests were filed in response to the board's communication pursuant to Article 15(1) RPBA. They represented an amendment to the respondent's case and should be treated according to Article 13(1) RPBA.

There was no persuasive reason for the late filing of these requests, since the objections made against the claims of auxiliary requests XI and XII had been present in the statements of grounds of appeal. Furthermore the claims of these requests give rise to new objections, for instance according to

Article 123(2) EPC and thus their admission would not

be procedurally economic.

Admissibility of auxiliary request XIX - Article 13(1) RPBA

This request was filed at the last possible moment during the appeal proceedings, i.e. during the oral proceedings before the board. It was therefore late filed and not to be admitted for that reason alone. Moreover, the subject-matter of the dependent claim 12 of the main request on which it was based had been objected to for lack of novelty (see statement of grounds of appeal of appellant II, page 16, third and fourth paragraphs). Thus, its subject-matter was not prima facie allowable, since it was not immediately apparent how it overcame the objection raised against auxiliary request XI.

Main request

Novelty - Article 54 EPC

The method of claim 1 was anticipated by document D1 which disclosed that:

i) an IgG2 antibody (alphaOPGL-IgG2) was produced by mammalian cells (Cell Line 125Q) and

ii) the IgG2 is secreted in the culture medium and thereby is contacted with a redox coupling reagent (cysteine/cystine) at pH 7 and simultaneously with a chaotropic agent (arginine). The cysteine and cystine concentration was about 0.20 mM each, with a cysteine:cystine ratio of about 1:1. This could be taken from Example 3 of document D1, where the composition of the culture medium used (VM-SoyBatch medium) was disclosed in Table 3.

Example 3 of document D1 disclosed the production of alphaOPGL-1 antibody in Cell Line 125Q, a clone derived from CHO cells that express the antibody from two plasmids, one encoding alphaOPGL-1-k (light chain) and the other encoding alphaOPGL-1-IgG2 (heavy chain) (page 89, paragraph[0218], first sentence). Accordingly, the alphaOPGL-1 antibody was an IgG2 antibody recombinantly produced in mammalian cells. Said antibody thus necessarily eluted as several separate forms on RP-HPLC. It was noted that the disclosure of the disputed patent itself in paragraphs [0073] to [0075] confirmed that heterogeneity was a general property of IgG2 antibody populations.

Furthermore, document D1 in Example 3 disclosed that "The antibody is further purified by cation exchange chromatography using SP Sepharose HP (Amersham Pharmacia) or equivalent. The cation exchange chromatography step removes additional CHO cell proteins, DNA, lower molecular weight proteins, and aggregated forms of alphaOPGL-1" (see paragraph [0229]). The removal of aggregated forms meant that the methods as a whole fell within the ambit of the claim.

The opposition division considered that there was no reason not to apply the principles of decision G 2/88 to the case at hand and that the method of claim 1 defined "an enrichment purpose based on a new technical effect obtained by process steps which have not been disclosed in the prior art".

The opposition division however miscategorised the subject-matter of claim 1 as a method achieving an effect, covered by decision G 2/88, whereas it was in fact a method of production of IgG2, as was readily apparent from the wording of the claim.

The case law of the boards of appeal in relation to methods of production (see e.g. T 304/08) consistently held that, for claims directed to a process for producing a product, the purpose (aside from the production) should not be regarded as a functional technical feature in the sense of decisions G 2/88 and G 6/88 but was limiting only to the extent that the method has to be suitable for that use.

The opposition division considered that document D1 did not disclose either the heterogeneity of IgG2 to be purified or that an alteration of the distribution of its forms was brought about by the steps of the treatment disclosed. However, both of these features were made available to the public by document D1.

The opposition division was also wrong to consider that the prior art must "show that the relative distribution of forms is altered by redox/chaotrope treatment" in order to anticipate the claimed subject-matter. The claim language did not support this conclusion because it did not require that the relative distribution of IgG2 forms was a direct result of the redox/chaotrope treatment, as this was merely one of several features of the method of claim 1.

Heterogeneity of IgG2, either recombinantly produced or isolated from serum, such as human serum, was a general property of IgG2s, while the alteration of the distribution of forms resulting from carrying out the method steps was the inevitable result of the contacting of the antibodies with a redox coupling reagent, cysteine/cystine, at pH 7. The concentration of this coupling reagent used in document D1 was about 0.20 mM each of cysteine and cystine with a ratio of about 1 to 1. This corresponded with a range suggested in the patent of about 0.1 mM to about 10 mM, see paragraph [0148] of the patent. In document D1, the secreted IgG2 was at the same time contacted with the chaotropic agent, arginine. The concentration of arginine used was not relevant to achieving an alteration of the distribution of the forms of the IgG2, either in the prior art or in the claimed method of the patent. This was because it was the redox reagent that led to the effect of altering the distribution of forms of IgG2.

In relation to the respondent's arguments that the concentration of cysteine used in document D1 was too low to achieve the effect of reducing the number of diluting forms of IgG2 antibody on RP-HPLC, it was noted that the concentration of 3 to 10 mg/mL present in the culture broth disclosed in document D1 fell exactly within the range of concentration mentioned in claim 7 of the main request.

XXI. The arguments of the respondent are summarised as follows.

Admissibility of the auxiliary requests I to XVIII - Article 12(2), 12(4) RPBA and Article 13(1) RPBA

Amendments to claims 20 to 22

No arguments were provided in writing in response to appellant II's objections relating to the lack of substantiation of the auxiliary requests either in the reply to the statement of grounds of appeal or in reply to the board's communication pursuant to Article 15(1) RPBA.

At the oral proceedings it was argued that auxiliary requests I to XVIII had been substantiated in the reply to the appellants' grounds of appeal (see section 3 of the reply). Moreover, essentially the same claim requests had been filed before the opposition division and had been substantiated then, being aimed at overcoming the novelty objections with regard to document D1. No party could now be surprised by the amendments made. It was therefore not justified not to admit any of these claim requests. Indeed, the amendments to the claims of the auxiliary requests were self-explanatory and were done to address the objections of lack of novelty raised in the statements of grounds of appeal of the appellants.

Moreover, any additional changes made were done in response to new objections raised by appellant II for the first time in the appeal or during the oral proceedings in the first instance. In particular, appellant II raised an objection under Article 100(c) EPC against claims 20 to 22, in

section 3.2 of their appeal. These claims had not been objected to for this reason before and the amendments to take this into account were made at the first opportunity. Similarly, the objections under

Article 100(b) EPC raised by appellant II against claims 20 to 22 (see section 4 of the statement of grounds of appeal) were raised for the first time during the oral proceedings before the opposition division and because they were unsuccessful, there had been no need at the time to file requests in response.

In relation to auxiliary requests XIII to XVIII, the subject-matter of claim 1 was amended to incorporate subject-matter from claims that were not objected to by the appellants. For instance, claim 1 of auxiliary requests XIII and XIV incorporated the subject-matter of claim 12 of the main request. Claim 1 of auxiliary requests XVII and XVIII incorporated the subject-matter from page 40, line 33 of the application as originally filed.

Admissibility of auxiliary requests XIa and XIIa - Article 13(1) RPBA

These requests were filed in case the board was inclined to adopt appellant II's position that the subject-matter of claim 1 of auxiliary requests XI and XII was not novel over document D1. In these requests, the purpose of the use was further clarified and now referred to enriching at least one of several IgG2 forms. Since document Dl did not employ chaotropes for this purpose, it could not prejudice the novelty of the claimed subject-matter.

Objection pursuant to Rule 106 EPC

During the course of the oral proceedings in not admitting auxiliary requests X, XIII to XVIII, the board infringed the respondent's right to be heard according to Article 113 EPC. Consequently an objection pursuant to Rule 106 EPC was made.

Admissibility of auxiliary request XIX - Article 13(1) RPBA

This request was based on admitted auxiliary request XI and represented a bona fide attempt to overcome the objection of lack of novelty against claim 1 of that claim request. Indeed, the amendment represented the addition of subject-matter from dependent claim 12 of the main request that had not been attacked for lack of novelty and was therefore straightforward.

Main request - claim 1

Novelty - Article 54 EPC

The respondent provided no written arguments on novelty beyond those set out in the decision under appeal. At the oral proceedings the respondent provided the following arguments.

The claimed subject-matter was novel over that disclosed in document D1 for the reasons set out in the decision under appeal. Firstly, document D1 did not directly and unambiguously disclose a method in which an initial IgG2 antibody eluted as several separate forms on RP HPLC nor that the method decreased the number of forms eluting. In response to the argument that document D1 explicitly disclosed the removal of aggregated forms of IgG2, it was pointed out that the entire disclosure of the patent made it clear that the separate forms referred to were isoforms and not aggregated forms. The claim required that the separate forms eluted separately from RP?HPLC and it was not known if this was true of aggregates.

Secondly, the concentration of cysteine used in Example 4 of the patent was 3 to 10 mg/mL. In document D1 the concentration of cysteine was 70 mg/L. The amount used in the patent was therefore 60 times higher than that used in document D1. The concentration of redox reagent used in D1 was too low to achieve the effect of decreasing the number of forms of diluting IgG2 antibody.

This argument was not a change of case in the sense of Article 13(1) RPBA. The arguments had been raised in the first instance proceedings and were considered by the opposition division in reaching their decision that document D1 did not anticipate the claimed subject-matter (see page 7 of the decision under appeal). It was up to the appellants to show that this decision was wrong.

Even if the arguments concerning the concentration of redox reagent were disregarded, the burden of proof lay with the appellants to show that the disclosure in document D1 was novelty destroying. They had not discharged this burden.

XXII. The appellants requested that the decision under appeal be set aside and that the patent be revoked.

XXIII. The respondent requested that

- the decision of the opposition division be maintained (amounting to a request that the appeals be dismissed);

- alternatively, that the patent be maintained on the basis of the set of claims of one of auxiliary requests I to XI, XIa, XII, XIIa, or XIII to XIX, auxiliary requests I to XVIII filed with the respondent's reply to the grounds of appeal, auxiliary requests XIa and XIIa filed with the respondent's letter dated 10 July 2019 and auxiliary request XIX filed during the oral proceedings before the board.