Appeals have been filed by the opponent and the patent proprietor against the opposition divisionâ€™s interlocutory decision to maintain European patent No. 2 170 949 in amended form according to auxiliary request 2. Claim 1 of auxiliary request 2 reads as follows:
"1. Method for concentrating an immunoglobulin solution by tangential flow filtration, characterized in that the transmembrane pressure and the cross-flow are variable and changed during the filtration process depending on the immunoglobulin concentration with
i) a transmembrane pressure of from 1.4 bar to 1.6 bar and a cross-flow of from 225 liters/m**(2)/h to 270 liters/m**(2)/h in a concentration range up to 30 mg immunoglobulin per ml of solution to be concentrated,
ii) a transmembrane pressure of from 0.8 bar to 0.9 bar and a cross-flow of from 420 liters/m**(2)/h to 480 liters/m**(2)/h in a concentration range of from 15 mg/ml up to 55 mg/ml,
iii) a transmembrane pressure of from 0.8 bar to 0.9 bar and a cross-flow of from 360 liters/m**(2)/h to 420 liters/m**(2)/h in a concentration range of from 50 mg/ml up to 275 mg/ml,
wherein the actual concentration of the immunoglobulin in the solution to be concentrated determines the applied transmembrane pressure and cross-flow and the transmembrane pressure and cross-flow are adjusted depending on the actual concentration of the immunoglobulin;
and wherein the membrane area is 0.02 m**(2)."
Auxiliary request 4
The subject-matter of claim 1 of auxiliary request 4 corresponds to the subject-matter of claim 1 of auxiliary request 2.
The claim relates to a method of concentrating an immunoglobulin solution by tangential flow filtration (TFF). The method is characterised in that a specific applied transmembrane pressure (TMP) and a specific cross-flow are adjusted stepwise during the filtration process, depending on the immunoglobulin concentration.
The opponent objected to the inventive step of claim 1 of auxiliary request 4 in view of D4 as the closest prior art. It relied on document A018.
During the oral proceedings, the patent proprietor requested that A018 not be admitted into the proceedings.
A018 was submitted by the opponent with the statement of grounds of appeal. The patent proprietor objected to the admittance of A018 neither in its reply to the grounds of appeal nor in its subsequent letters. The request not to admit A018 thus represented an amendment to the patent proprietor's case.
Any amendment to a party's appeal case made after notification of a summons to oral proceedings shall, in principle, not be taken into account unless there are exceptional circumstances which have been justified with cogent reasons by the party concerned.
Since A018 was filed with the statement of grounds of appeal, its admittance could have been objected to before the oral proceedings. The board sees no reason, and no reason has been cited by the patent proprietor, why this was not done. There are thus no exceptional circumstances which could justify the request made by the patent proprietor during the oral proceedings.
For these reasons, the board has decided not to admit the patent proprietor's request into the proceedings in accordance with Article 13(2) RPBA 2020.
The aim of the patent is to improve flux performance (shorten the overall concentration time) and to reduce aggregate formation in a method of concentrating an immunoglobulin solution. A reduced aggregate formation correlates with a higher quality product.
D4 relates to a method for concentrating monoclonal antibodies. The method involves the use of a tangential flow mini-cassette implying a TFF process. D4 does not refer to immunoglobulin. However, since immunoglobulin is a monoclonal antibody, the aim of D4 is similar to that of the patent in suit.
Thus, D4 constitutes a suitable closest prior art document in the assessment of the inventive step of the subject-matter of claim 1 of auxiliary request 4.
The distinguishing feature of claim 1 of auxiliary request 4 in view of D4 is that the TMP and the cross-flow are adjusted stepwise during the filtration process depending on the immunoglobulin concentration.
The patent proprietor formulated the objective technical problem as being the provision of a TFF method resulting in fewer agglomerates in a certain processing time or the same number of agglomerates in a shorter processing time.
A018 shows that the technical problem as formulated by the patent proprietor is not solved over the whole scope of claim 1. The objective technical problem has to be formulated in a less ambitious way as the provision of an alternative TFF method.
The arbitrary selection of TMP and cross-flow values during the process as defined in claim 1 of auxiliary request 4 cannot be regarded as having inventive merit. Such an arbitrary selection implies nothing more than a routine adjustment of these two process parameters. For that reason, the subject-matter of claim 1 of auxiliary request 4 does not involve an inventive step.
The board has concluded that the subject-matter of claim 1 of the main request and of each of auxiliary requests 1 to 3, 5 and 6 does not involve an inventive step in view of D4 for the same reasons as those given for the subject-matter of claim 1 of auxiliary request 4.
The patent is revoked.