Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 04/13/2026 has been entered.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
This action is in response to the papers filed on March 12, 2026. Pursuant to amendment filed March 12, 2026, claims 1 and 55 are amended. Claims 4-5, 7, 9-14, 19-54, 57-114, 117-120, 122, and 124 have been canceled.
Election/Restrictions
Applicant's election without traverse of Group I, directed to a method of perfusion culturing a mammalian cell and method of producing a recombinant protein, was previously acknowledged. Claims 4-5, 7, 9-14, 19-54, 57-114, 117-120, 122, and 124 have been canceled. No withdrawn non-elected claims remain pending in the application.
Therefore, claims 1-3, 6, 8, 15-18, 55-56, 115-116, 121, 123, 125-127 are currently under examination.
Priority
This application is claiming the benefit under 35 U.S.C. 119(e) of prior-filed U.S. provisional application 63/174,900, filed April 14, 2021. Thus, the earliest possible priority for the instant application is April 14, 2021.
Information Disclosure Statement
The information disclosure statements (IDS) submitted on 12/12/2025, 02/12/2026, 02/26/2026, 03/12/2026, 04/13/2026, and 04/16/2026 were filed. The submissions are in compliance with the provisions of 37 CPR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
New Claim Rejections - 35 USC § 112
Claim 1, 15-18, 55, 121, 123, and 2-3, 6, 8, 56, 115-116, 125-127 by dependence, are newly rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre - AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 1 and 55 recite incubating the mammalian cell “for a period of time” and further recite that various process steps occur “during the period of time” or “over the period of time.” The metes and bounds of the claimed “period of time” mare unclear because the claims do not specify, or otherwise provide objective boundaries for determining, the duration of the period of time. For instance, it is unclear if the period of time encompasses hours, days, weeks, months, or any other duration sufficient to perform the claimed culturing method. Since the duration of the claimed “period of time” affects the scope of the required incubation, perfusion, conductivity monitoring, osmolality maintenance, salt solution addition, and achievement of recited viable cell density, the ordinary artisan would not be reasonably apprised of the scope of the claimed invention with reasonable certainty.
Claims 15-18, 121, and 123 additionally recite “period of time.” These claims are additionally indefinite because the ordinary artisan would not be reasonably apprised of the scope of the claimed invention with reasonable certainty for at least the same reasons discussed above with respect to claims 1 and 55. Specifically, the claims do not provide objective boundaries for determining the duration of the recited “period of time,” and the duration affects the scope of the recited process steps, including adjustment of the pH or pCO2 over the period of time, and performing such adjustments based on viable cell density over the period of time.
Claims 2-3, 6, 8, 56, 115-116, 125-127 are rejected for being dependent from the rejected claims 1 and 55 and also for failing to further clarify the basis of the rejection.
Maintained Claim Rejections - 35 USC§ 103
Claims 1-3, 6, 8, 15-18, 55-56, 115-116, 121, 123, 125-127 remain rejected under 35 U.S.C. 103 as being unpatentable over Coffman et al. (US 2022/0340948 A1, filed September 27, 2019), in view of Crowley et al. (US 9,260,695 B2, prior published March 27, 2014), Villiger-Oberbek et al. (US 2016/0017280 A1), and further in view of Konstantinov et al. (US 2020/0317726 A1), Liu (WO 03/039459 A2), Cheng (US 2010/0035342 A1), and Tharmalingam et al. (Biotechnology and Bioengineering, Vol. 112, No. 4, April, 2015., see IDS filed 07/17/2022, Desig. ID 123).
Regarding claim 1, 121, and 126, Coffman teaches perfusion-based methods offer potential improvements over batch and fed batch methods, including improved product quality and stability, improved scalability, and increased cell specific productivity ([0003]). Unlike batch and fed-batch bioreactors, perfusion systems involve the continuous removal of spent media. By continuously removing spent media and replacing it with new media, the levels of nutrients are better maintained which simultaneously optimizes growth conditions and removes cell waste products. The diminished waste products reduce toxicity to the cells and the expression products. Thus, perfusion bioreactors typically result in significantly less protein degradation and thus, a higher quality product. Product can also be harvested and purified much more quickly and continuously, which is particularly effective when producing a product that is unstable. Perfusion bioreactors are also more easily scalable. As compared to traditional batch or fed-batch systems, perfusion bioreactors offer several advantages with regard to scalability and/or increasing demand ([0003-0004]). Coffman also teaches the internal conditions of the bioreactor, including, but not limited to pH and temperature, can be controlled during the culturing period. Those of ordinary skill in the art would have recognized and been able to select, suitable bioreactors for use in practicing the present invention based on the relevant considerations. The cell cultures used in the methods of the present invention can be grown in any bioreactor suitable for perfusion culture. The particular type of bioreactor is not particularly limited and can encompass all types of bioreactors suitable for perfusion cell culture ([0076]). Similarly, the cells cultured are taught to include CHO cells ([0162]; [0203]; [0235]).
Regarding the first and second liquid culture media, Coffman teaches a compartmentalized serum-free cell culture perfusion medium comprising the medium components subgrouped into at least three separate aqueous concentrated feeds and a diluent ([0017]). Coffman additionally teaches a method of culturing mammalian cells expressing a heterologous protein in perfusion culture, comprising: (a) inoculating a bioreactor with mammalian cells expressing a heterologous protein in a serum-free cell culture medium; (b) culturing the mammalian cells in a perfusion culture by continuously feeding the mammalian cells with a serum-free cell culture perfusion medium feed and removing spent media while keeping the cells in culture, wherein the serum-free cell culture perfusion medium feed is (i) a compartmentalized serum-free cell culture perfusion medium comprising the medium components subgrouped into at least three separate aqueous concentrated feeds and a diluent, wherein the first concentrated feed is an alkaline concentrated feed, the second concentrated feed is an acidic concentrated feed and the third concentrated feed is a near neutral concentrated feed; and wherein the compartmentalized serum-free cell culture perfusion medium is pH adjusting to neutral pH upon mixing of the at least three separate aqueous concentrated feeds and the diluent in the resulting serum-free cell culture perfusion medium; and/or (ii) the serum-free cell culture perfusion medium obtainable by the method according to the invention, and wherein the alkaline concentrated feed, the acidic concentrated feed and the near neutral concentrated feed of the serum-free cell culture perfusion medium feed are added separately to the cell culture and/or the reaction vessel of the bioreactor and wherein the diluent is added separately to the cell culture and/or the reaction vessel of the bioreactor or the diluent is premixed with one of the at least three separate aqueous concentrated feeds immediately before addition to the cell culture and/or the reaction vessel of the bioreactor ([0025]).
Concerning the limitations of osmolality ranges claimed, Coffman teaches a method where the growth of the cell culture can be controlled by increasing the residual osmolality to physiologically stressful levels (about 350-400 mOsm or higher) while remaining below the cytotoxic level (about 400 mOsm or higher) ([0014]). Coffman teaches methods of adjusting volume of the different liquid culture medias to optimize for target cell density. Once the target viable cell density is reached the osmolality may be increased to suppress cell growth, such as increased by about 10-70%, about 10-60% or about 10-50% of the optimal osmolality level for growth of the mammalian cell. The osmolality should be increased gradually or step wise. In one embodiment the osmolality is increased to about 350 mOsm or higher, preferably to about 380 mOsm or higher, to about 400 mOsm or higher, to about 420 mOsm or higher or to about 450 mOsm or higher. The increased osmolality results in maintaining the cells during production phase at about target viable cell density without affecting viability. Thus, increasing the osmolality reduces or eliminates the need for cell bleeding during production phase. By increasing the osmolality in the cell culture, cell growth may be suppressed to maintain a sustainable viable cell density without cell bleeding, particularly a high viable < 100x106 cell density without cell bleeding, such as <100x106cells/ml, preferably < 120x106 cells/ml, which may also be referred to as a dynamic perfusion culture ([0139]).
Further, regarding the limitation of a viable cell density of greater than 60 x 106 cells/mL, Coffman teaches achieving high cell culture densities accounts for part of the greater productivity of perfusion systems. In a typical large-scale fed-batch commercial cell culture process, cell densities of 10-50 x 106 cells/mL can be reached. However, with perfusion-based bioreactors, extreme cell densities of > 1 x 108 cells/mL have been achieved. In addition, in perfusion mode, high cell numbers are sustained for much longer periods of time through the continuous replenishment of spent media. The higher cell densities for increased periods of time in perfusion bioreactors accounts in part for their more efficient performance ([0005]). Coffman additionally teaches the target viable cell density is about 30x106 cells/ml or higher, about 60x106 cells/ml or higher, about 80 x 106 cells/ml, preferably about 100x106 cells/ml or higher, and osmolality may be controlled using (a) a constant concentrated feed perfusion rate and a varying diluent perfusion rate, resulting in a varying overall perfusion rate ([0027]). During the production phase of the method, a typical target cell density may reach ranges from about 10 x 106 cells/mL to 150 x 106 cells/mL ([0086]), and even densities as high as 200 x 106 cells/mL have been achieved ([0132]).
Coffman specifies that perfusion-based methods offer potential improvement over the batch and fed-batch methods by adding fresh media and simultaneously removing spent media. Large scale commercial cell culture strategies may reach high cell densities of 60-90x 106 cells/mL, at which point about a third to over half of the reactor volume may be biomass. With perfusion-based culture, extreme cell densities of > 1 x108 cells/mL have been achieved. Typical perfusion cultures begin with a batch culture start-up lasting for a day or more to enable rapid initial cell growth and biomass accumulation, followed by continuous, stepwise and/or intermittent addition of fresh feed media to the culture and simultaneous removal of spent media with retention of cells throughout the growth and production phases of the culture. Various methods, such as sedimentation, centrifugation, or filtration, can be used to remove spent media, while maintaining the cells. Perfusion flow rates of a fraction of a vessel volume per day (VVD) up to many multiple vessel volumes per day have been utilized ([0056]). A typical viable cell density at steady state is 10 to 50x106 cells/ml. The viable cell density may vary depending on the perfusion rate. A higher cell density can be reached by increasing the perfusion rate or by optimizing the medium for use with perfusion. At a very high viable cell density perfusion cultures become difficult to control within a bioreactor ([0058]). It is not inventive to find optimal workable ranges by routine experimentation. See In re Aller, 220 F.2d 454,456, 105 USPQ 233,235 (CCPA 1955). Moreover, it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. In re Aller, 105 USPQ 233.
Regarding the limitations of continuous monitoring the conductivity of the liquid culture mediums with an online conductivity sensor and the controlled addition of a salt solution by the online conductivity sensor, Coffman additionally teaches the osmo balance is capable of targeting a higher or lower residual osmolality by adjusting concentrates and diluent rate, whereas the chemical additives approach those others have used can only adjust osmolality in the increasing direction to help maintain high viability in a cell culture ([0014]). Furthermore, prior art previously made of record, such as Crowley teaches a person skilled in the art knows how to determine the outflow rate. The outflow rate of the liquid is determined by the perfusion rate and is generally chosen at an equal value (column 4, lines 8-10). The perfusion rate is dependent on the cell density of the culture, and both the flow rate and the dilution rate are adjusted as the cell density in the fermenter increases (column 8, lines 66-67 through column 9, lines 1-2).
Also, Villiger-Oberbek teaches a method of culturing a mammalian cell, the method comprising providing a vessel, wherein systems are taught to optimize the effect of changing any of the various cell culturing parameters, including the volume, height, diameter, or bottom shape of a well, the frequency or type of agitation, the sheer force, the culture seeding density, the pH of the first or second liquid culture medium, dissolved CO2 concentration or partial pressure, the inner surface coating of the well, the various contents within a liquid culture media (e.g., the first and/or second liquid culture media), the mammalian cell type or line, the CO2 exposure or dissolved CO2 concentration or partial pressure, O2 the temperature, the volume of liquid culture medium ( e.g., the volume of the first and/or second liquid culture media), and/or the rate or frequency of removing the first volume of the first culture medium and adding the second volume of the second culture medium to the first culture medium) ([0087]). Villiger-Oberbek further teaches that incubation should be conducted for a period of time at about 31 °C to about 40°C ([0012] and [0086]); and continuously or periodically, during the period of time, removing a first volume of the first liquid culture medium and adding to the first liquid culture medium a second volume of a second liquid culture medium, wherein the first and second Volumes are about equal ([0086], [0088] and Claim 1). Villiger-Oberbek additionally teaches the use of a fluid flow regulator with the ability to control flow rate and/or flow direction by detecting changes in volume and pressure. Furthermore, it is taught that fluid flow regulators can be programmed to flow fluid at a specific rate for a specific period of time in a specific flow direction, into and/or out of the culture vessels ([0100]).
One of ordinary skill in the art would have been motivated to combine the teachings of the cited references to maintain the optimal cell culture media at selected points during the culture period. In doing so, the POSITA would have recognized the benefit of modulating cell culture parameters such as temperature, pCO2, and osmolality by increasing, decreasing, or programming flow rates at defined intervals during the cell culture process. The known technique of adjusting flow rates to reach optimal environmental conditions, as taught individually by Coffman, Crowley, and Villiger-Oberbek, would have rendered it prima facie obvious to apply this technique to optimize the osmolality control strategy in a perfusion system using online monitoring.
Furthermore, the ordinary artisan would have recognized that the methodological feature of automating the adjustment of flow rate or continuously monitoring the conductivity of the culture medium in the bioreactor using an online conductivity and maintaining the osmolality by the addition of salt solution controlled by the sensor was a established method in the field of bioreactor design and perfusion culturing, further in view of teachings from Konstantinov, Liu, and Cheng.
Konstantinov teaches methods of biomanufacturing of recombinant proteins, where conductivity meters are utilized along with operating system that utilizes software for liquid buffer regulation ([0090-0092]; [0095-0098]; Example 3).
Liu similarly teaches bioreactor culturing methods where tangential flow filtration system includes calibration by conductivity monitors, where the elution process is under the control and maintenance of such system able to monitor conductivity level continuously ([00195]; [00233; 00243]; [00245]; claim 217).
Likewise, Cheng teaches methods for controlling the level of dissolved carbon dioxide and limiting osmolality in a mammalian cell culture process to enhance cell growth, viability density, and increase biologic product concentration and yield, including the monitoring of osmolality along with active control of parameters (Abstract; [0008]; [0012]; [0109]).
Thus, before the effective filing date, the ordinary artisan would have found it obvious to combine the teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng, each of which teaches regulation of a cell culture conditions, such as pH, osmolality, dissolved gasses, and viable cell density, for the purposes of optimizing mammalian cell viability, productivity, and process stability. These references teach substantially similar methodologies involving concentrated media feeds, feedback-controlled input systems, and online monitoring (including via conductivity sensors) to achieve precise control over culture conditions. Given their analogous subject matter, overlapping process objectives, and complementary control strategies, a person of ordinary skill in the art would have a reasonable expectation of success integrating the conductivity-based osmolality control and salt feed strategies, using known bioreactor instrumentation and perfusion design principles.
The content from the previous rejection is hereby incorporated by reference in its entirety, and repeated as follows:
Villiger-Oberek additionally teaches that cell culture and recombinant protein production include adding a volume of a third culture medium, and even a possible fourth, where the total volume of liquid culture medium should be about equal or less than the first liquid culture medium volume ([0157]). Hence, all the essential elements of these claims' (monitoring of osmolality, an adjustment in flow and perfusion rate of a third volume in either direction) parameters during the process of culturing living cells would have been obvious, to one of ordinary skill in the art, as taught in both of these references. These teachings are beneficial to produce cell culture conditions that can utilize the monitoring and adjustment of a first and second media volume with a third to better control essential parameters for cell culture viability and possible product yield (possible products being a protein.)
Specifically, regarding osmolality ranges, for instance about 800 mOsm/kg to about 2,500 mOsm/kg of the second liquid culture medium, Coffman teaches that this is a concentrated feed (claim 1). As a concentrated feed, there is no required physiologically optimum range. Coffman additionally teaches the concentrated feed having osmolality of 1500-1700±50 mOsm ([0218- 0228]). Further, it would have been prima facie obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have optimized the ranges of commonly known factors, such as concentrations and volumes, adjusting to reach a specific range of cell densities.
Before the effective filing date of the instant application, Crowley teaches the pH, temperature, dissolved oxygen concentration and osmolarity of the cell culture medium are in principle not critical and depend on the type of cell chosen. Preferably, the pH, temperature, dissolved oxygen concentration and osmolarity are chosen such that it is optimal for the growth and productivity of the cells. The person skilled in the art knows how to find the optimal pH, temperature, dissolved oxygen concentration and osmolarity for the perfusion culturing. Usually, the optimal pH is between 6.6 and 7 .6, the optimal temperature between 30 and 39° C., the optimal osmolarity for viable cells culturing between 260 and 400 mOsm/kg (column 2, lines 43- 53). It has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. Moreover, it is not inventive to find optimal workable ranges by routine experimentation. See In re Aller, 220 F.2d 454,456, 105 USPQ 233,235 (CCPA 1955). Therefore, a person of ordinary skill would have been motivated to optimize the range of osmolality and other known physiological factors for optimal cell growth.
A recitation of the intended use in the preamble of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim. If a prior art structure is capable of performing the intended use as recited in the preamble, then it meets the claim. See, e.g., In re Schreiber, 128 F.3d 1473, 1477, 44 USPQ2d 1429, 1431 (Fed.Cir. 1997). In this instance, the perfusion devices and methods in the prior art were capable of performing intended use as recited bioreactor perfusion culturing continuously at a covered range of osmolality and adjusting volumes accordingly.
It would have been prima facie obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have combined the prior art elements taught by Coffman, such as bioreactor perfusion culturing methods using similar ranges and methodological design with teachings of Crowley of optimal perfusion culturing conditions, as both of these teachings communicate analogous and known methods, to yield the predictable result of generating conditions for optimal cell culturing for a designated cell type, with a reasonable expectation of success.
Regarding claim 2, the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng render claim 1 obvious. Moreover, Coffman teaches the optimal osmolality level for growth in a cell culture is cell line dependent and may be between about 280 mOsm to about 390 mOsm (mOsmol/kg water). Some cell lines may still grow optimally at an osmolality above 390 mOsm. The optimal osmolarity level for growth of a mammalian cell in a cell culture depends on the mammalian cell used and possibly also the culture conditions and may be easily determined by determining the viable cell density and viability at different osmolality; the optimal osmolality level is cell density independent and but is preferably determined at about target viable cell density ([0138]).
Regarding claim 3 and 6, the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng render claim 1 obvious. Moreover, Coffman teaches a surfactant may be Pluronic F68 ([0068]), and Crowley teaches examples of detergents include Pluronic F68 (column 2, line 36), equivalent to the claimed species of a poloxamer-188, see instant specification pg. 46, para. 3-4.
However, these combined teachings do not expressly teach the use of the general poloxamers at greater than 8 g/L.
However, Tharmalingam teaches that Pluronic F68 (P-F68) is an important component of chemically defined cell culture medium because it protects cells from hydrodynamic and bubble-induced shear in the bioreactor. While P-F68 is typically used in cell culture medium at a concentration of 1 g/L (0.1 %), higher concentrations can offer additional shear protection and have also been shown to be beneficial during cryopreservation. Recent industry experience with variability in P-F68-associated shear-protection has opened up the possibility of elevated P-F68 concentrations in cell culture media (Abstract).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng with the disclosure of Tharmalingam on utilizing Pluronic F68, as a species of poloxamer, at a concentration of greater than 8 g/L. One of ordinary skill in the art would have been motivated to make this modification by the teaching that Pluronic F68 is beneficial to protect cells from forces in the cell culture perfusion bioreactor and help to maintain cell culture viability (Abstract). The courts have also found that "where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). See MPEP 2144.05 II.
Regarding claim 8, the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng render claim 1 obvious. Moreover, Coffman teaches culture medium may also contain supplementary components that enhance growth and/or survival above the minimal rate, including ions, such as sodium, chloride ([0067-0068]; [0164]). The ordinary artisan would have found it obvious to implement sodium chloride as the species of salt solution, as equilibration buffers were known to comprise salts, such as sodium chloride, further in view of Liu’s teachings ([00206]).
Regarding claims 15-18, the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng render obvious the limitations of claims 1. Furthermore, Coffman teaches the invention relates to a serum-free cell culture perfusion medium comprising the medium components subgrouped into at least three separate aqueous concentrated feeds and a diluent, wherein the resulting serum-free cell culture perfusion medium is pH-adjusting to neutral pH upon mixing (Abstract). Villiger-Oberek additionally teaches methods of monitoring the change in partial pressure of pH and dissolved CO2 based on perfusion rate in all directions (para. [0085-0087]). More precisely, Villiger-Oberek teaches the methods to further include periodically adding an additional volume of second liquid culture medium to each of the plurality of wells in order to offset any decrease in the volume of the first liquid culture medium due to evaporation. In some embodiments of any of the methods described herein, the removing of the first volume of the first liquid culture medium and the adding to the first liquid culture medium the second volume of the second liquid culture medium is performed using an automated device. In some embodiments of any of the methods described herein, the method results in a viable cell density of between 15x106 cells/mL 60x106 cells/mL in the well ([0011]).
Hence, an adjustment in flow and perfusion rate of these parameters during the process of culturing living cells would have been obvious for one of ordinary skill in the art as taught in both of these references. One of ordinary skill in the art would have been motivated to combine these teachings to produce cell culture conditions that can utilize an adjustment of different media volumes and essential parameters for cell culture viability and possible product yield (possible products being a protein.)
Regarding independent claims 55-56, 115-116, 123, and 125-127 (a method of producing a recombinant protein), the combined teachings of Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, and Cheng render obvious all limitations, as previously explained. The only additional limitation not already previously rendered obvious is the recovering of a recombinant protein from the mammalian cell, as a method of producing a recombinant protein.
In regard to this limitation, Coffman teaches methods further comprising culturing mammalian cells or producing a protein of interest and harvesting the protein from the perfusion cell culture. Coffman's invention contemplates any suitable method for harvesting and purifying the protein of interest. The harvesting may also occur intermittently throughout the cell culture life cycle, or at the end of the cell culture. Harvesting is preferably done continuously from the permeate, which is the supernatant produced after cells have been recovered by a cell retention device. Due to the lower product residence time of the product proteins in the cell culture inside the perfusion bioreactor compared to fed batch, the exposure to proteases, sialidases and other degrading proteins is minimized, which may result in better product quality of heterologous proteins produced in perfusion culture ([0148] and claims 12-13).
In this same respect, Crowley teaches a biological substance is produced by the cells. The biological substances that can suitably be produced in the perfusion culturing of the cell are in principle all biological substances that can be produced by animal, especially mammalian, and yeast cells, for example therapeutic and diagnostic proteins (claims 10-11 and column 4, lines 50-55). Additionally, Villiger-Oberbek teaches methods of producing, recovering, isolating, and formulating a recombinant protein from these cell culture processes. Villiger-Oberbek teaches recovering means partially purifying or isolating a recombinant protein from one or more components present in the cell culture medium or lysate (claims 3, 10, 11, 52).
All references cited, Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, Cheng, and Tharmalingam, are directed to bioreactor culturing of mammalian cells and collectively teach perfusion culturing, flow regulation, osmolality control, and recombinant protein production. It would have been obvious to a person of ordinary skill in the art, before the effective filing date, to combine these teachings with well-known conductivity-based feedback systems, as taught by references such as Konstantinov, Liu, to maintain osmolality via controlled salt addition. This combination would have predictably enhanced cell viability and protein yield under perfusion conditions, addressing known challenges in bioprocess control and cell viability. The ordinary artisan would have additionally found it obvious to use the known techniques to improve similar commentary methods of producing a recombinant protein, utilizing mammalian cell bioreactor culturing, and been motivated to make this combination for the manufacturing of recombinant protein at large scales, in view of the taught design incentives.
Response to Applicants’ arguments as they apply to the rejection of claims 1-3, 6, 8, 15-18, 55-56, 115-116, 121, 123, 125-127 under 35 USC § 103
Applicant’s arguments filed March 12, 2026, have been fully considered but they are not persuasive.
At pages 6-13 of the remarks filed March 12, 2026, Applicants essentially argue the following:
Applicant argues that a person of ordinary skill in the art would not have been motivated to use the conductivity sensors described in Konstantinov and Liu in a cell culture process because those references concern chromatography and filtration rather than cell culture.
The argument has been previously responded to in the Final Rejection and remains unpersuasive. The applicant’s amendments do not sufficiently overcome the state of the art nor prior art referenced. Additionally, the Applicants’ arguments do not present the teachings of the individual references in their whole context or acknowledge the combination of references.
Applicant’s amendment to claims 1 and 55, reciting that the osmolality is “continuously maintained” at about 270 mOsm/kg to about 380 mOsm/kg, has been fully considered, but the prior art rejection already relied on Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, Cheng, collectively for a perfusion culture process with osmolality-sensitive control conditions, automated monitoring, and feedback-based adjustment of process variables. The newly added recitation of “continuously” does not materially distinguish the claims over the cited combination because the references already teach continuous perfusion operation, continuous automated monitoring, and active control of culture parameters and systems for producing a recombinant protein during the perfusion period. The amendments do not overcome the previously stated rationale for combination.
The Examiner respectfully submits that patents are relevant as prior art for all they contain. "The use of patents as references is not limited to what the patentees describe as their own inventions or to the problems with which they are concerned. They are part of the literature of the art, relevant for all they contain." In re Heck, 699 F.2d 1331, 1332-33, 216 USPQ 1038, 1039 (Fed. Cir. 1983). With that, a reference may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art, even nonpreferred embodiments. See MPEP § 2123: Merck & Co. v. Biocraft Labs., Inc. 874 F.2d 804, 10 USPQ2d 1843 (Fed. Cir. 1989), cert. denied, 493 U.S. 975 (1989); Upsher-Smith Labs. v. Pamlab, LLC, 412 F.3d 1319, 1323, 75 USPQ2d 1213, 1215 (Fed. Cir. 2005).
Regarding the use of conductivity sensors, in the instant case, Konstantinov does teach cell culture where the liquid culture medium is obtained from cell culture, including from a fed-batch cell or a perfusion cell culture ([0121]), Konstantinov explicitly teaches culturing method, including perfusion cell culture ([0181]; [0198]; [0217-0218]). Likewise, Liu teaches cell culture methods throughout ([0035]; [0041-0082]; claims 1, 47, 52, 60, 69, 78). In view of the teachings of Konstantinov and Liu, and combination of references, the ordinary artisan would have recognized that conductivity was a known and continuously measured process variable used in automated fluid-handling systems.
Applicant further argues that one skilled in the art would not have been motivated to continuously maintain osmolality in a bioreactor by addition of a salt solution in view of Coffman, because Coffman states that “preferably no further additive (such as NaCl)” is added to increase osmolality.”
This argument is not persuasive because Coffman does not teach away. Rather, where cited by applicant, Coffman teaches controlling osmolality in a perfusion culture to regulate viable cell density and suppress growth at high cell densities, including target densities above 100 x 106 cells/mL by adjusting perfusion feed conditions and overall osmolality in the bioreactor. Coffman further teaches that osmolality control may be achieved by manipulating feed and diluent rates and calculating osmolality balances within the culture system. While Coffman states that “preferably no further additive (such as NaCl)” is used for increasing osmolality, this statement reflects a preferred implementation, in a specific instance, rather than a clear teaching away from all salt-based osmolality adjustment. Coffman teaches the central concept of actively controlling osmolality in a perfusion bioreactor to regulate cell growth and maintain high viable cell densities.
3.) Applicant argues none of the cited prior art references (alone or in combination) teach or suggest continuously monitoring the conductivity of liquid culture medium in a bioreactor over a period of time using an online conductivity sensor and continuously maintaining the osmolality of the liquid culture medium in the bioreactor over the period of time by addition of a salt solution controlled by the online conductivity sensor.
This argument is not persuasive because it does not accurately acknowledge Coffman’s teachings, and broadly attacks references individually out of context. For instance, Coffman thoroughly teaches the feed to comprise salts throughout ([0019]; [0068]; [0072]; [0102]; [0104]; [0164]; [0176]; [0207]). The argument that Coffman doesn’t teach the addition of a salt solution is not accurate.
In view of the prior art of record, regarding salt solutions, the ordinary artisan would recognize the relationship between salt, salt solution conductivity, and cellular osmolarity was known in the prior art. While applicant cites “preferably no further additive (such as NaCl) is added to the culture for increasing the osmolality,” this is out of context from the broader disclosure of Coffman’s perfusion cell-culture methods. Read in context, Coffman teaches a perfusion culture system in which osmolality is actively controlled by mixing multiple concentrated feed solutions with diluent in the bioreactor, with the feed/diluent ratio determining both osmolality and fold-concentration of the resulting cell culture medium, and with osmo-balance levels used to adjust feed rates to achieve desired residual osmolality and nutritive level ([0121-0143]). Thus, Coffman’s reference to no further NaCl as an additive is not accurately characterized. Coffman references salt solutions as a contrast to chemical salt additives. Coffman states,
“[0011] Osmolality has been a known lever to impact cell growth. Prior art using osmolality to affect cell growth is known in the literature. However, the ability to control a cell culture process to a target osmolality, particularly in perfusion culture has never been established. Also, chemical additives affect media composition and/or need to be cleared in subsequent purification steps, thereby increasing process complexity. Chemical additives including salts may also affect product quality.
[0012] In view of the challenges with perfusion cell culture such as prepared media consumption and the desire to further increased productivity, media that improve logistic problems and methods that are effective in suppressing cell growth in the perfusion state and avoid the need for cell bleeding without further additives would significantly help advance the art.” ([0011-0012])
Likewise, Applicants’ reference-by-reference arguments directed to Coffman, Crowley, Villiger-Oberbek, Konstantinov, Liu, Cheng, and Tharmalingam attack references individually and often rely on selective citations, out of context, rather than addressing the rejection as a whole. In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
For instance, Applicant’s arguments present Liu’s teachings as only directed to “methods of preparing viral vector particles and viral vector particle compositions,” citing the Abstract. It is clear that Liu teaches cell culture along with monitoring systems, as Liu states:
“The method of the invention includes obtaining a population of viral vector particle producing (packaging) cells, adapting the cells, if necessary, to a suitable culture medium, propagating the cells in the medium and under conditions suitable for production of viral vector particles…. The method can ideally be performed using one or more automated programmable monitoring systems, which regulate key parameters in the production process.” ([0005])
Liu also teaches perfusion cell culture ([0045-0047]; [0057-0059]; [00112-00113]). Liu explicitly states, “The viability of cells can be monitored and/or determined by any appropriate technique, including those discussed elsewhere herein ([00125]).” Liu additionally teaches methods of monitoring the system, including cellular monitoring and automated programmable parameter monitors ([0050]; [00125]; [00169]; [00178]; [00183]; [00245-00248]). Moreover, Konstantinov also teaches cell culture along with adjacent systems related to producing recombinant proteins and recovery (Example 3). Applicant cites [0283], but [0280-0282] clearly show that the cellular systems are related to the systems for recovering the recombinant proteins, such as chromatography.
Applicant is reminded the Court commented that "[r]esponding to concerns about uncertainty in the prior art influencing the purported success of the claimed combination, this Court [in O'Farrell] stated: “[o]bviousness does not require absolute predictability of success ... all that is required is a reasonable expectation of success."' Kubin, 561 F.3d at 1360 (citing In re O'Farrell, 853 F.2d at 903-904).
4.) The examiner has already responded to applicants’ arguments directed to teachings of monitoring using an online conductivity sensor. Applicant repeats that none of the cited references, alone or in combination, teach or suggest continuously monitoring conductivity of liquid culture medium in bioreactor using an online conductivity sensor and continuously maintaining osmolality in the bioreactor by addition of a salt solution controlled by the online conductivity sensor.
This argument has also been previously responded to. The response is reiterated, here:
Applicant’s arguments are not persuasive because the rejection does not rely on any single reference to teach the entire claimed inventions. In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
In response to applicant’s argument that there is no teaching, suggestion, or motivation to combine the references, the examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
In this case, applicant’s arguments with respect to the “online conductivity sensor” and controlled by an online conductivity sensor” limitations are not persuasive because the cited references collectively teach the required elements and motivation to combine them. Konstantinov and Liu teach continuous conductivity monitoring within automated fluid-handling systems, establishing conductivity as a known process-control variable in continuous bioprocess operations. Cheng teaches using measured osmolality as a control input to drive automated adjustments in mammalian cultures. Coffman and Crowley teach the method of perfusion and osmolality-sensitive operating framework. Thus, the ordinary artisan would have found it obvious to adapt a recognized, continuously measured parameter such as conductivity, already taught to be used in automated feedback loops, to regulate osmolality via salt addition in a perfusion system represents a predictable application of known control principles.
Applicant’s arguments do not overcome the prima facie case of obviousness, and the arguments of counsel cannot take the place of evidence in the record. In re Schulze, 346 F.2d 600, 602, 145 USPQ 716, 718 (CCPA 1965). Examples of attorney statements which are not evidence, and which must be supported by an appropriate affidavit or declaration include statements regarding unexpected results, commercial success, solution of a long-felt need, inoperability of the prior art, invention before the date of the reference, and allegations that the author(s) of the prior art derived the disclosed subject matter from the inventor or at least one joint inventor.
Conclusion
Claims 1-3, 6, 8, 15-18, 55-56, 115-116, 121, 123, 125-127 are rejected. No claims are allowed.
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/J.D.L./Examiner, Art Unit 1633
/FEREYDOUN G SAJJADI/Supervisory Patent Examiner, Art Unit 1699
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