T 1306/11 (Tangential flow concentration of cell suspensions/PARKER-HANNIFIN) 04-04-2014

I. The appeal lies from the decision of the examination division to refuse European patent application

n°01950382.0.

II. The application was refused on the grounds that the respective Claims 1 of each of the main, first and second auxiliary requests then on file lacked clarity (Article 84 EPC) and that the claimed process according to Claim 1 of the third auxiliary request then on file was obvious over document D3 (WO 98/35746 A1) taken as the closest prior art.

III. With its statement setting out the grounds of appeal, the appellant inter alia filed amended sets of claims as main request and auxiliary requests.

IV. In reaction to the summons to oral proceedings, with letter dated 10 March 2014, the appellant withdrew some of its previous requests and re-filed the accordingly renumbered remaining requests.

V. In preparation for oral proceedings, the board issued a communication indicating its provisional view regarding some of the salient issues of the case. Document D6 (US 5,947,689 A), acknowledged in the application as filed, was referred to.

VI. In response to the Board's communication, the appellant, with its letter dated 24 March 2014, filed further amended sets of claims as new first, second, third and fourth auxiliary requests.

VII. In a telephone conversation held on 2 April 2014, the rapporteur drew the attention of the applicant’s representative to some of the points which might still need to be discussed at the oral proceedings and issued a fax communication summarising the issues addressed.

VIII. At the oral proceedings held on 4 April 2014 the issues mentioned in the Board's communications, in particular the clarity issues, were addressed exhaustively. The appellant submitted a new main request, replacing the main and first auxiliary requests previously on file. At the end of the oral proceedings the decision was announced.

IX. Claim 1 according to the main request filed at the oral proceedings reads as follows (amendments to Claim 29 as originally filed made apparent by the Board):

"1. An automated tangential flow filtration method for[deleted: filtering liquids while maintaining a substantial trans-membrane pressure] concentrating cell suspensions, for use in the pharmaceutical or biotechnology industries, the method comprising:

providing, [deleted: with]in a reservoir (21) [deleted: a liquid having a filterable material dissolved or suspended] a supply (22) of a cell suspension within a carrier liquid;

providing a membrane filtration unit (24) having an inlet (28), a [deleted: filtrate] permeate outlet (29) and a retentate outlet (31);

[deleted: receiving] passing liquid to be filtered by operation of a pump unit (25) through the inlet of the filtration unit and separating at least some [deleted: filterable] material therefrom as [deleted: filtrate] permeate from the [deleted: filtrate] permeate outlet;

passing a retentate of the carrier liquid and residue [deleted: filterable] material from the retentate outlet;

directing the liquid from the retentate outlet and recycling it to the reservoir (21);

providing [deleted: at least one pressure] a first sensor (S1) for sensing the pressure of the liquid passing through the inlet, to monitor an inlet pressure (P1);

providing a second pressure sensor (S2) at the retentate outlet for monitoring the retentate pressure (P2) and a third pressure sensor (S3) at the permeate outlet for monitoring permeate pressure (P3) [deleted: and valve positioned ][deleted: along a location for monitoring and modifying pressure];

providing a processor (41) with control logic for adjusting the pump rate imparted to the liquid by the pump unit;

wherein

the method further includes:

providing a valve (36,30) [deleted: positioned ][deleted: along a location ]for [deleted: monitoring and] modifying pressure at the permeate outlet (29), at the retentate outlet (31), or at each of the permeate outlet and retentate outlet, the control logic of the processor being also for adjusting the valve or valves, the adjustment of the pump rate and valve or valves being for modifying pressure at the outlet or outlets;

passing the liquid through a flow meter (35) at a location upstream of the filtration unit;

determining an optimal feed rate and an optimal trans-membrane pressure across the membrane filtration unit for the particular filtration unit and for the particular process solution of the liquid for pharmaceutical or biotechnology use being filtered;

maintaining a substantially constant trans-membrane pressure that substantially coincides with the optimal trans-membrane pressure across the membrane filtration unit while maintaining a substantially constant feed rate that substantially coincides with the optimal feed rate;

said maintaining including controlling movement rate of the liquid through the filtration unit, including receiving data from the pressure sensors, calculating from the inlet pressure and the outlet pressures the trans-membrane pressure across the filtration unit, comparing the thus calculated trans-membrane pressure with [deleted: a selected] the optimal trans-membrane pressure, and if a deviation between the calculated and [deleted: selected] optimal transmembrane pressure occurs, varying the pressure at at least one of the pressure sensors so that the calculated trans-membrane pressure substantially coincides with the [deleted: selected] optimal trans-membrane pressure across the membrane filtration unit;

said maintaining further including receiving data from the flow meter and directing the pump unit to modify the flow rate detected by the flow meter in order to maintain a substantially constant feed rate into the membrane filtration unit which substantially coincides with the optimum [deleted: flow] feed rate; and

said determining of the optimal trans-membrane pressure includes detecting the amount of filtrate which passes through the permeate outlet as filtrate amount data received by the control logic, whereby the transmembrane pressure value and the feed rate value are varied and the filtrate collection amount is monitored to detect an optimal trans-membrane pressure value and optimal feed rate achieving a maximum collection rate, and setting the optimal feed rate and optimal transmembrane pressure as thus determined for said maintaining step;

thereby achieving a maximum collection rate in the concentration of the cell suspension by tangential flow filtration without affecting the viability of the cells."

X. The appellant requested that the decision under appeal be set aside and that a European patent be granted on the basis of the main request submitted during oral proceedings, or, alternatively, according to one of the second, third or fourth auxiliary requests filed with letter dated 24 March 2014.

XI. The appellant's arguments concerning the main request can be summarised as follows:

a) The new main request should be admitted into the proceedings, for the following reasons:

i) Since the decision under appeal found that the claims of the third auxiliary request were clear and based on the application as filed, the appellant was not aware of any objections under Articles 84 or 123(2) EPC as raised by the Board for the first time in its communication, so that it was not possible for the appellant to file earlier a claim request addressing these objections.

ii) The new claims addressed all the objections raised by the Board in its communications.

iii) The main request was thus clearly admissible.

b) As to the amended claims of the main request, they were based on the application as filed, and were also clear in all aspects of the claimed process, such as automation, tangential flow filtration, concentration of cell suspensions and recycling.

c) Document D6, referred to by the Board, and not one of documents D1 to D4 used by the Examining Division, was the most relevant starting point with respect to the claimed subject-matter, but inventive step arguments regarding D6 had not yet been considered. Hence, remittal to the first instance was appropriate.