EP 2 513 135 B1 relates to improved processes for purifying polypeptides of interest, by increasing the amount of a polypeptide of interest bound to a cation-exchange matrix relative to the amount of one or more impurities bound to the ion-exchange matrix.
Brief outline of the case
The OD maintained the patent according to AR1. Both proprietor and opponent appealed.
The board held claim 1 as maintained as lacking IS. AR2-7 were not admitted under Art 12(3) RPBA for lack of substantiation.
At the end of the OP the proprietor withdrew its appeal and the approval of all requests. The patent was thus revoked.
The proprietor’s point of view
The claimed subject-matter of the MR was a second non-medical use of the type considered in decisions G 2/88, G 6/88, T 279/93 and T 892/94.
The claim at stake was of the type whose subject-matter should be recognised as novel under G 2/88 because it related to the use of a known compound for a new purpose not made available in the prior art – i.e. “the reduction of host cell proteins (HCPs) in the purification of a polypeptide of interest by cation-exchange chromatography”.
A number of decisions, cited by the proprietor, supported the view that the criteria set out in G 2/88 can be applied to claims like those in the MR, with claims whose wording meant that their subject-matter was the use of a known substance for a new purpose, based on a technical effect described in the patent, even though the new use was in the context of a process.
For the proprietor, where a claim was directed to a second non-medical use, novelty could be established by a specific technical effect, not previously disclosed
In the present case the effect was reducing HCPs. This was a feature of the claimed use and had not been disclosed or suggested in the prior art. Thus, even if the same compounds had been used in prior processes, the purpose and effect claimed in the MR, had not previously been made available to the public.
The new effect – i.e. competing for CEX binding and attaining the effect of reducing HCP impurities, was therefore to be treated as a functional technical feature of the claim and, provided the prior art did not make available the use of the known compound for the same purpose or effect, it imparted novelty to the claimed subject-matter.
The opponent’s point of view
For the opponent, even if the reduction of host cell proteins was not disclosed in any of the cited documents, which was disputed, the claimed subject-matter was not novel under the principles established in T 892/94.
A newly discovered technical effect could not confer novelty on the use of a known substance for a known non-medical purpose if the newly discovered technical effect already underlay the known use of the known substance.
In the present case, the claimed non-medical purpose was purification of polypeptides using cation-exchange chromatography (CEX). This was not novel. The reduction of host cell proteins (HCP) was actually a technical effect of the old non-medical use, i.e. it was an explanation of a mechanism by which the purification was achieved and as such had to be disregarded as a feature of the claim.
The board’s decision
When construing a claim, the claimed subject-matter is determined by applying the established principles of claim construction, i.e. giving the terms used in a claim their ordinary meaning in the context of the claim in which they appear. This principle also applies when determining what “category” a claim is in, e.g. whether it is directed to a product or process.
In G 2/88, the EBA made a distinction between categories of claims, namely between those directed to a use of a physical entity for achieving an effect on the one hand and those directed to a process for the production of a product on the other.
The EBA emphasised that a claim directed to the use of a known compound for a particular purpose is not a process claim within the meaning of Art 64(2). A “use” claim of the type considered by the EBA, does not result in a product and therefore no protection under Art 64(2) arises.
The board referred to T 1913/21, published after the OP in the present case, for an analysis of the relevant case law of the boards on second non-medical uses and with a focus on which claimed subject-matter was subject to the principles established by G 2/88 and G 6/88.
For the board, the prevalent established jurisprudence, in particular with regard to the fact that the effect recited in the claim must relate to the use, rather than to the product directly obtained by the process steps within the meaning of Art 64(2), in order to constitute a limiting feature in the sense of G 2/88.
Application to the present case
For the board, it is apparent that the purpose or aim defined in the claim can only be achieved in the context of a method or process for purification of a polypeptide of interest by cation-exchange chromatography.
The aim “the reduction of host cell proteins” can only be achieved if the entire purification process is actually carried out and most importantly, the technical effect relied on is a property of the final product, i.e. an eluate containing an increased ratio of the polypeptide of interest to host cell proteins, i.e. the purified polypeptide.
Thus, following the principles laid down in G 2/88 and G 6/88 and the jurisprudence implementing them, the board concluded that the claimed subject-matter must be regarded as a process for the purification of a polypeptide of interest, in other words as a method for the production of an eluate with “an increased ratio of the polypeptide of interest to host cell proteins in the eluate”.
The technical effect “reduction of host cell proteins” cannot occur except as part of a process leading to the production of a product, here purified polypeptides, and as such is inextricably linked to the production process.
The board considered that the purified polypeptides produced by the claimed process would be covered by Art 64(2) as “products directly obtained” by the claimed process.
In the present case, drafting the claim as a “use” of a chemical compound cannot mask the fact that the claim defines a production/purification process and the new technical effect can only take place in the context of this process.
The mere formatting of the claim to give the appearance that its subject-matter falls under the principles established by G 2/88 cannot circumvent the fact that on analysis, the claim is directed to a use or process for the production of a product, here one having the ‘improved‘ property of having ‘reduction of host cell proteins’.
Moreover, the alleged new technical effect of reduction of host cell proteins pertains to the product, the polypeptide, and cannot be considered a technical limiting feature of the “use” according to G 2/88.
Novelty
In view of the board’s claim construction, the effect mentioned in the claim is not a feature of the claimed process to be taken into account for assessing N.
As D2 discloses a process for the purification of a polypeptide by means of CEX chromatography wherein a chemical compound falling with the definition provided in the claim, is added to both loading and elution fluids. D2 thus anticipates the presently claimed subject-matter. The same applied to D4 and D5.
Comments
Drafting a claim as defining a “use” does not necessarily make its subject-matter falling under the situation decided under G 2/88 and G 6/88. If on analysis, the subject-matter of the claim defines a process to obtain a specific product, falling under Art 64(2), G 2/88 and G 6/88 are not applicable.
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