A Method of Capturing and/or Purifying a Target
20220184526 · 2022-06-16
Inventors
Cpc classification
C07K1/36
CHEMISTRY; METALLURGY
International classification
B01D15/36
PERFORMING OPERATIONS; TRANSPORTING
B01D15/38
PERFORMING OPERATIONS; TRANSPORTING
C07K1/36
CHEMISTRY; METALLURGY
Abstract
There is provided a chromatography system comprising a first valve in fluid connection to a first chromatography column and/or a second valve; the second valve in fluid connection to a second chromatography column and the first valve; wherein the first valve and the second valve are operable to provide: a mode that selectively allows a fluid to flow from the first chromatography column to the second chromatography column; and one or more modes that selectively allows the fluid to bypass the first chromatography column and/or the second chromatography column. Also disclosed is a method of capturing and/or purifying a target from a sample thereof. In one embodiment, an acidic protein, alpha-1 anti-trypsin (A1AT), is purified by a tandem column configuration using anion exchange chromatography, whereby a first chromatography column is added in between the sample pump and an injection valve, or replaced the sample loop of AKTA system.
Claims
1. A chromatography system comprising: a first valve in fluid connection to a first chromatography column and/or a second valve; the second valve in fluid connection to a second chromatography column and the first valve; wherein the first valve and the second valve are operable to provide: i) a mode A that selectively allows a fluid to flow from the first chromatography column to the second chromatography column; ii) a mode B that selectively allows the fluid to bypass the first chromatography column; and/or iii) a mode C that selectively allows the fluid to bypass the second chromatography column.
2. The system of claim 1, wherein the first valve in fluid connection to the first chromatography column and the second valve in fluid connection to the second chromatography column are in tandem arrangement.
3. The system of claim 1, wherein the first valve is operable to selectively allow fluid flow to flow through the first chromatography column; or to bypass the first chromatography column, optionally wherein an outlet of the first valve is linked to an inlet of the second valve; optionally wherein the second valve is operable to selectively allow fluid flow to flow through the second chromatography column or to bypass the second chromatography; optionally wherein: i) in the mode A, the first valve directs the fluid to flow from the first chromatography column connected to the first valve to the second chromatography column connected to the second valve; ii) in the mode B, wherein the first valve directs the fluid to bypass the first chromatography column, thereby directing the fluid to flow from the first valve to the second chromatography column connected to the second valve; and iii) in the mode C, wherein the first valve directs the fluid to flow through the first chromatography column connected to the first valve to the second valve that directs the solution to bypass the second chromatography column.
4.-6. (canceled)
7. The system of claim 1, wherein the first valve is an injection valve, optionally the second valve is a column valve.
8. The system of claim 1, wherein the first chromatography column is a flow-through chromatography column or a bind & elute chromatography column and the second chromatography column is a flow-through chromatography column or a bind & elute chromatography column
9. The system of claim 1, wherein the first chromatography column is a flow-through chromatography column and the second chromatography column is a bind & elute chromatography column, optionally wherein the system directs fluid to flow in mode A and in mode B, sequentially.
10. (canceled)
11. The system of claim 1, wherein the second valve is a column valve, optionally wherein the first chromatography column is a bind & elute chromatography column and the second chromatography column is a flow-through chromatography column, optionally wherein the system directs fluid to flow in mode C and in mode A, sequentially, optionally wherein the first chromatography column is a bind & elute chromatography column and the second chromatography column is a bind & elute chromatography column, optionally wherein the system directs fluid to flow in mode C, in mode A and in mode B, sequentially.
12.-15. (canceled)
16. The system of claim 1, wherein the system further comprises one or more valve, optionally the valve is selected from the group consisting of an injection valve and a column valve.
17. The system of claim 1, wherein the first chromatography column and/or the second chromatography column is an affinity or non-affinity chromatography, or wherein the first chromatography column and/or the second chromatography column is an anion exchange chromatography, optionally wherein the first chromatography column is a high salt tolerant anion exchanger and/or the second chromatography column is a conventional anion exchange chromatography, high salt tolerant anion exchange chromatography and/or an affinity chromatography.
18.-19. (canceled)
20. The system of claim 1, wherein the first chromatography column is a Toyopearl NH2 750F, optionally the second chromatography column is a bind & elute chromatography column selected from the group consisting of a conventional anion exchanger, a high salt tolerant anion exchanger, and an affinity chromatography, optionally wherein the first chromatography column is a Toyopearl NH2-750F and/or the second chromatography column is selected from the group consisting of Toyopearl Super Q-650, Capto Q, Q Sepharose, Mustang® Q, Sartobind Q, HyperCel Star AX, Poros XQ, and Alpha-1 Antitrypsin Select.
21. (canceled)
22. A method of purifying a target from a sample, comprising: a) providing a system according to any one of the preceding claims, and b) collecting the target from the system.
23. The method of claim 22, wherein the first chromatography column is a flow-through chromatography column or a bind & elute chromatography column and the second chromatography column is a flow-through chromatography column or a bind & elute chromatography column, optionally wherein the first chromatography column is a flow-through chromatography column and the second chromatography column is a bind & elute chromatography column, optionally wherein when the system directs fluid to flow in mode A and in mode B, sequentially, the target is collected in mode B by disassociating the target from the second chromatography column.
24.-25. (canceled)
26. The method of claim 22, wherein the first chromatography column is a bind & elute chromatography column and the second chromatography column is a flow-through chromatography column, optionally wherein when the system directs fluid to flow in mode C and in mode A, sequentially, the target is collected in mode A by dissociating target from the first chromatography column and flow through the second chromatography column, or wherein the first chromatography column is a bind & elute chromatography column and the second chromatography column is a bind & elute chromatography column, optionally wherein when the system directs fluid to flow in mode C, in mode A and in mode B, sequentially, the target is collected in mode B by disassociating the target from the second chromatography column.
27.-29. (canceled)
30. The method of claim 29, wherein the target is a target protein, optionally an acidic protein.
31. The method of claims 22, wherein the target is a recombinant acidic protein, optionally an alpha-1 anti-trypsin (A1AT).
32. The system of claim 1, wherein the purification is no less than about 90% pure, or no less than about 91%, or no less than about 92%, or no less than about 93%, or no less than about 94% or no less than about 95%, or no less than about 96%, or no less than about 97%, or no less than about 98%, or no less than about 99%.
33. The method of claim 22, wherein the sample is a supernatant (such as cell culture supernatant).
34. The method of claim 22, wherein the first valve, the second valve, the first chromatography column and the second chromatography column are integrated in a single closed- and self-contained apparatus.
35. The method of claim 22, wherein the purification is no less than about 90% pure, or no less than about 91%, or no less than about 92%, or no less than about 93%, or no less than about 94% or no less than about 95%, or no less than about 96%, or no less than about 97%, or no less than about 98%, or no less than about 99%.
36. The system of claim 1, wherein the first valve, the second valve, the first chromatography column and the second chromatography column are integrated in a single closed- and self-contained apparatus.
Description
BRIEF DESCRIPTION OF FIGURES
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EXAMPLES
[0173] Example embodiments of the disclosure will be better understood and readily apparent to one of ordinary skill in the art from the following discussions and if applicable, in conjunction with the figures. It should be appreciated that other modifications related to structural, electrical and optical changes may be made without deviating from the scope of the invention. Example embodiments are not necessarily mutually exclusive as some may be combined with one or more embodiments to form new exemplary embodiments.
Chromatography Configurations
[0174] There are two main types of chromatography: (1) positive chromatography/bind & elute chromatography/capture; and (2) negative chromatography/flow-through chromatography. When there is more than one chromatographic step, the steps typically involve: (1) a capture (initial recovery) step; (2) an intermediate step; and (3) a polishing step.
[0175] In process development, product recovery is prioritized over purity in the capture step. Therefore, bind & elute chromatography (as opposed to flow-through chromatography) is almost always preferred as it is able to concentrate and reduce the volume of intermediate products for further purification. Even though flow-through chromatography may have its advantage of removing aggregates, it is rarely used in the capture step.
[0176] This disclosure describes a combination (amalgamation) of flow-through and bind & elute chromatography in a single step purification that gives high purity and high yield. Advantageously, the tandem column configuration can be applied in existing Fast Protein Liquid Chromatography (FPLC) system, resulting in excellent performance in terms of purity and recovery. No modification of hardware is required in order to switch on or off the individual columns connected in series.
[0177] The function of an injection valve in an ÄKTA system (e.g. ÄKTA Pure) is typically to channel sample from sample pump or sample in sample loop to a chromatography column located downstream (see
[0178] On the other hand, a column valve typically used for bypassing a chromatography column or to change the position of a chromatography column in some examples. The column valve enables multiple columns to be attached at different positions. However, only single column position may be used at one time. Currently, where tandem columns are used, they are connected to the same position and the first column is removed when necessary. Alternatively, an additional column valve is commonly installed to achieve bypassing. However, this is not desirable. For modulus system such as ÄKTA Pure, column valve (V9-C in
[0179] In some examples, this disclosure describes bypassing first chromatography column. In some examples, it is not necessary to bypass the second chromatography column when flow-through chromatography is paired with bind & elute chromatography. Therefore, embodiments of the method may desirably work on FPLC system without existing column valve.
[0180] The tandem configuration described is applicable to different models of ÄKTA systems of different scales from laboratory to pilot scale. Conventionally, injection valve is used to inject a sample into a column connected at column valve. For “inject” mode in an ÄKTA system (e.g. ÄKTA Purifier 100), fluid may flow from a first position (e.g. see position 6 in
[0181] The flowchart shown in
[0182] To illustrate, in one example, to operate tandem configuration on ÄKTA Purifier/Explorer with a sample pump, the first column is connected to the outlet of sample pump and position 2 on the injection valve while the second column is connected to the column valve as per normal (
[0183] In one example, the first column was connected to an injection valve and operated in flow-through mode while the second column was connected to a column valve located downstream and operated in bind and elute mode. During column equilibration, the injection valve was changed to “Inject” mode while column valve was changed to the selected “Column position”. Equilibration buffer was allowed to flow from a sample pump to the first column connected to an injection valve, followed by the second column connected to a column valve and all the sensors located downstream. Once the pH and conductivity stabilize, sample valve was switched to the sample line in which the sample was loaded to these two columns connected in series. When a desired amount of sample was applied to the system, the sample pump switched to equilibration buffer line to push the remaining sample caused by system dead volume to the column. In this sample application phase, the first column bound the impurities while the second column bound the target protein. The unbound components were collected as flow-through.
[0184] After completing the sample application, the sample pump was stopped and the injection valve was changed to “Load” mode in order to bypass the column. Equilibration buffer from the system pump was directed from the injection valve, bypassing the first column, to the second column position at column valve. This is to further remove all the unbound components from the column. UV absorbance was observed to approach baseline indicating the absence of proteins.
[0185] Finally, during elution, system pump was switched to elution buffer. The target protein was dissociated from the column and collected as an eluate. It is crucial to bypass the first column, especially during the elution phase as the elution buffer would cause bounded impurities to dissociate, thus contaminating the eluate from the second column when pooled together. This would significantly compromise the process performance in terms of purity.
[0186] Under the same binding conditions, the first column operating in flow-through mode was able to capture impurities such as CHO host cell proteins, host DNA/RNA and aggregates. This allows the supernatant to be pre-treated before entering the second column, where target protein in the supernatant binds predominantly.
[0187] During elution, the first column was bypassed with only the second column in line. The target protein was eluted by changing the buffer condition, and both columns can be regenerated under the same conditions.
[0188] Embodiments of the method may be particularly useful when applied in the capture step. The following examples will therefore demonstrate embodiments of the method in the context of the capture step. However, it will be understood that embodiments of the method described herein can be applied and/or adapted for any of the purification steps mentioned above (including intermediate step and polishing step) without departing from the spirit of the invention.
[0189] Purification of Alpha-1 antitrypsin (A1AT) expressed in CHO cell culture is carried out in the following examples. A1AT is an acidic protein with theoretical isoelectric point (pl) of 5.37 and molecular weight (MW) of 52 kDa.
Process Design With Tandem Chromatography Column
[0190] The chromatography system as disclosed herein may include four possible combinations (see Table 1 below).
TABLE-US-00001 TABLE 1 Possible tandem chromatography combinations Purification mode of first Purification mode of second Combination chromatography column chromatography column 1 Flow-through Bind & elute chromatography chromatography 2 Bind & elute Flow-through chromatography chromatography 3 Bind & elute Bind & elute chromatography chromatography 4 Flow-through Flow-through chromatography chromatography
Examples of hardware installation of columns the corresponding fluid flow path on ÄKTA Explorer/Purifier/Pure/Avant can be found in
i) First Column is Flow-Through Mode and Second Column is Bind & Elute Mode
[0191] The sample flows from first column (via injection valve at “INJECT” command) to second column (via column valve at “Column position” command); [0192] Subsequently, first column is bypassed (via injection valve at “LOAD” command) and elution buffer will only dissociate target from second column. [0193] Sample application phase of first column will overlap with sample application phase of second column
TABLE-US-00002 TABLE 2 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when flow-through chromatography is paired with bind & elute chromatography with sample application via sample pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration Sample pump - Inject In line Selected In line Waste First equilibration column manner buffer position (mode A) 2.1 Sample Sample Sample pump - Inject In line Selected In line Fractionator FIG. 3.2 application application sample column FIG. 5.2 position 2.2 Complete Complete Sample pump - Inject In line Selected In line Fractionator sample sample equilibration column application application buffer position 3 Idle Wash System pump - Load Bypass Selected In line Waste Second wash buffer or column manner equilibration position (mode B) buffer (only if FIG. 3.3 equilibration FIG. 5.3 buffer is same as wash buffer) 4 Idle Elution System pump - Load Bypass Selected In line Fractionator elution buffer column position
TABLE-US-00003 TABLE 3 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when flow-through chromatography is paired with bind & elute chromatography with sample application via system pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration System pump - Inject In line Selected In line Waste First equilibration column manner buffer position (mode A) 2.1 Sample Sample System pump - Inject In line Selected In line Fractionator FIG. 4.2 application application sample column FIG. 6.2 position 2.2 Complete Complete System pump - Inject In line Selected In line Fractionator sample sample equilibration column application application buffer position 3 Idle Wash System pump - Load Bypass Selected In line Waste Second wash buffer or column manner equilibration position (mode B) buffer (only if FIG. 4.3 equilibration FIG. 6.3 buffer is same as wash buffer) 4 Idle Elution System pump - Load Bypass Selected In line Fractionator elution buffer column position
ii) First Column is Bind & Elute and Second Column is Flow-Through Mode
[0194] Sample will flow to first column only (via injection valve at “INJECT” command) while second column (via column valve at “column bypass” command) is bypassed during sample application and wash; [0195] During elution, target will dissociate from the first column (via injection valve at “INJECT” command) and flow to second column (via column valve at “selected column position”); [0196] Elution phase of first column will overlap with the sample application phase of second column.
TABLE-US-00004 TABLE 4 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when bind & elute chromatography is paired with flow-through chromatography with sample application via sample pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration Sample pump - Inject In line Selected In line Waste First equilibration column manner buffer position (mode A) FIG. 3.2 FIG. 5.2 2.1 Sample Idle Sample pump - Inject In line Column Bypass Fractionator Third application sample Bypass manner 2.2 Complete Idle Sample pump - Inject In line Column Bypass Fractionator (mode C) sample equilibration Bypass FIG. 3.4 application buffer FIG. 5.4 3 Wash Idle Sample pump - Inject In line Column Bypass Waste wash buffer or Bypass equilibration buffer (only if equilibration buffer is same as wash buffer) 4 Elution Sample Sample pump - Inject In line Selected In line Fractionator First application elution buffer column manner position (mode A) FIG. 3.2 FIG. 5.2
TABLE-US-00005 TABLE 5 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when bind & elute chromatography is paired with flow-through chromatography with sample application via system pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration System pump - Inject In line Selected In line Waste First equilibration column manner buffer position (mode A) FIG. 4.2 FIG. 6.2 2.1 Sample Idle System pump - Inject In line Column Bypass Fractionator Third application Sample Bypass manner 2.2 Complete Idle System pump - Inject In line Column Bypass Fractionator (mode C) sample equilibration Bypass FIG. 4.4 application buffer FIG. 6.4 3 Wash Idle System pump - Inject In line Column Bypass Waste wash buffer or Bypass equilibration buffer (only if equilibration buffer is same as wash buffer) 4 Elution Sample System pump - Inject In line Selected In line Fractionator First application elution buffer column manner position (mode A) FIG. 4.2 FIG. 6.2
iii) First Column is Bind & Elute Mode and Second Column is Bind & Elute Mode
[0197] Sample will flow to first column only (via injection valve at “INJECT” command) while second column (via column valve at “column bypass” command) is bypassed during sample application and wash; [0198] During elution, target will dissociate from the first column (via injection valve at “INJECT” command) and flow to second column (via column valve at “selected column position”); [0199] During 2nd elution, first column will be bypassed (via injection valve at “load” command); [0200] Elution phase of first column will overlap with the sample application phase of second column.
TABLE-US-00006 TABLE 6 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when bind & elute chromatography is paired with bind & elute chromatography with sample application via sample pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration Sample pump - Inject In line Selected In line Waste First equilibration column manner buffer 1 position (mode A) FIG. 3.2 FIG. 5.2 2.1 Sample Idle Sample pump - Inject In line Column Bypass Fractionator Third application sample Bypass manner 2.2 Complete Idle Sample pump - Inject In line Column Bypass Fractionator (mode C) sample equilibration Bypass FIG. 3.4 application buffer 1 FIG. 5.4 3 Wash Idle Sample pump - Inject In line Column Waste wash buffer 1 or Bypass equilibration buffer 1 (only if equilibration buffer is same as wash buffer) 4 Elution Sample Sample pump - Inject In line Selected In line Fractionator First application elution buffer column manner position (mode A) FIG. 3.2 FIG. 5.2 5 Idle Wash System pump - Load Bypass Selected In line Waste Second wash buffer 2 column manner position (mode B) 6 Idle Elution System pump - Load Bypass Selected In line Fractionator FIG. 3.3 elution buffer 2 column FIG. 5.3 position
TABLE-US-00007 TABLE 7 Operating command for tandem column operated on ÄKTA Explorer/Purifier/Pure/Avant when bind & elute chromatography is paired with bind & elute chromatography with sample application via system pump Phase Phase Injection First Column Second Fluid of 1.sup.st of 2.sup.nd valve column valve column flow column column Inlet command status command status Outlet path 1 Equilibration Equilibration System pump - Inject In line Selected In line Waste First equilibration column manner buffer 1 position (mode A) FIG. 4.2 FIG. 6.2 2.1 Sample Idle System pump - Inject In line Column Bypass Fractionator Third application sample Bypass manner 2.2 Complete Idle System pump - Inject In line Column Bypass Fractionator (mode C) sample equilibration Bypass FIG. 4.4 application buffer 1 FIG. 6.4 3 Wash Idle System pump - Inject In line Column Bypass Waste wash buffer 1 or Bypass equilibration buffer 1 (only if equilibration buffer is same as wash buffer) 4 Elution Sample System pump - Inject In line Selected In line Fractionator First application elution buffer column manner position (mode A) FIG. 4.2 FIG. 6.2 5 Idle Wash System pump - Load Bypas Selected In line Waste Second wash buffer 2 column manner position (mode B) 6 Idle Elution System pump - Load Bypas Selected In line Fractionator FIG. 4.3 elution buffer 2 column FIG. 6.3 position
iv) First Column is Flow-Through Mode and Second Column is Flowthrough Mode
[0201] The operator is free to install both columns at column valve; [0202] Sample application phase of first column will overlap with the sample loading phase of second column
Materials and Methods
A. Chemicals, Biological Material and Chromatography Resins
[0203]
TABLE-US-00008 Chemicals 2-(N-Morpholino)ethanesulfonic Acid Sigma-Aldrich/ (MES) Merck 2-[4-(2-Hydroxyethyl)-1-piperaziny1]- ethanesulfonic acid (HEPES) Tris(hydroxymethyl)aminomethane (Tris) Sodium chloride (NaCl) Acetic acid Hydrochloric acid (HCl) Sodium hydroxide (NaOH) Magnesium chloride (MgCl2) Arginine Ethylenediaminetetraacetic acid (EDTA) Sodium azide Proteinase K Roche Alpha 1 Native human alpha 1 Antitrypsin protein (Abcam) Antitrypsin reference standard Filtered cell Alpha 1 Antitrypsin was expressed by mammalian cell culture culture in Chinese hamster ovary. To remove cell debris, supernatant cell culture harvest was first centrifuged at 4000 × g for 20 (FCCS) min at room temperature, followed by filtration through 0.22 μm membrane (Nalgene ® Rapid-Flow Filters, Thermo Scientific). The filtered cell culture supernatant (FCCS) was then stored at 2-8° C. for short-term usage or −80° C. for long-term storage. FCCS was measured to be at approximately pH7.0 13 mS/cm. A1AT concentration and purity in FCCS varied from batch to batch. Clarified cell 150 ml of FCCS was mixed with 20 mg of Activated charcoal culture (Sigma-Aldrich Cat. No. 161551) per ml of sample for 4 h. supernatant Subsequent filtration was done using SartoClear CAP PC1 (FCCS-AC) filter (Sartorius) and 0.22 μm membrane (Nalgene ® Rapid- Flow Filters, Thermo Scientific) FCCS was measured to be at approximately pH7.0 10 mS/cm. A1AT concentration and purity in FCCS-AC varied from batch to batch. Chromatographic TOYOPEARL SuperQ-650 M (Tosoh Bio-science) resins TOYOPEARL NH2-750F (Tosoh Bio-science) HyperCel STAR AX (Pall) Poros XQ (Thermo Scientific) Alpha-1 Antitrypsin Select (GE Healthcare)
B. Experimental Methods
High Throughput Screening Plate
[0204] A 96-well filter plate with 0.2 μm hydrophilic polypropylene (GHP) pore-membrane (Pall) and 350 μl wells (Axygen) was used for screening with the help of Multi-Well Plate Vacuum Manifold (Pall). Each incubation step was performed under shaking at room temperature using rotatory shaker (Microplate Genie) at low frequency.
[0205] 50 μl of working slurry (5 μl of settled resins) were transferred into each well using 12-channel pipette and the liquid was filtered off. 2×200 μl of equilibration buffer were added and incubated for 10 min. For each well, an appropriate amount of supernatant was loaded. The filter plate was then covered and incubated for 60 min or 120 min. Afterwards, a wash step was carried out with 3×200 μl of equilibration buffer and shaking for 5 min. Lastly, 2×100 μl of elution buffer were used with 10 min incubation time. The filtrate during elution was collected in a standard 96-well plate.
Chromatography Instrumentation and Operation
[0206] Depending on the desired bed volume, chromatographic resins were packed in house using Tricorn 5 or Tricorn 10 columns (GE healthcare) and attached to ÄKTA FPLC (GE Healthcare). For conventional batch mode, a single column was connected to the column valve. As for tandem column configuration, the first column was connected to the injection valve and the second column was connected to the column valve. Column volume (CV) is defined as the volume of the column connected to column valve. pH, conductivity and UV absorbance (A280 and A254) of the solution were monitored by built-in probes in ÄKTA FPLC. In the context of tandem column configuration, CV is defined based on the volume of bind & elute column.
[0207] Generally, the column/columns was first conditioned with 5 CV of equilibration buffer to achieve desired pH and conductivity. A known amount of target protein was loaded to the column/columns via either sample pump or system pump. In order to achieve complete loading, 10 ml of wash buffer was introduced to overcome the dead volume of the system before column valve. Subsequently, 10 CV of additional wash buffer was added to help to remove the unbound material from the column.
[0208] For flow-through (FT) chromatography in which impurities were bound to the column instead of target protein, flow-through was collected. In contrast, for bind & eluate (B&E) chromatography in which the target protein bound to the column, either step or gradient elution was performed to dissociate the target protein from the column and sample was subsequently collected as a purified product. In the context of anion exchanger and affinity chromatography, proteins were eluted with increasing conductivity.
[0209] Buffers were prepared using the chemicals listed in part A. 1M HCl or 5M NaOH was used to adjust the buffer pH to the desirable condition. If required, pH of sample was adjusted using 1M Tris or 1M Acetic acid while the conductivity was lowered using MilliQ water.
Design of Experiment (DoE) Using MODDE
[0210] For optimization of process parameters, a central composite face (CCF) design was applied using MODDE 12.1 (Umetrics). Based on the response collected, a contour plot was generated to determine the optimal operating condition.
C. Analytical Methods of Target and Impurities
Analytical Size Exclusion Chromatography Using HPLC
[0211]
TABLE-US-00009 Column TSK-GEL G2000SWxlcolumn (Tosoh Bio-science) Flow rate 0.6 mL/min Buffer 50 mM MES pH 6.0, 20 mM EDTA, 200 mM arginine & 0.05% Sodium azide Injection 50 ul volume Calibration UV absorbance (A.sub.280) of known quantity (0.05, 0.10, 0.20, 0.40, 0.60, 0.80 and 1.00 mg/ml) of native human alpha 1 Antitrypsin protein (abcam) was used as calibration curve. Base on the calibration, monomeric peak at retention time of 13 to 14 min is used to quantify the amount of A1AT in the unknown sample. Any peaks appeared before the main peak are considered as high molecular weight species (HMW) while any peaks appeared after the main peak are considered as low molecular weight species (LMW). Hence, the percentage purity of main peak is calculated based on the UV absorbance of monomeric peak over UV absorbance of all peaks (FIG. 13).
A1AT Activity
[0212]
TABLE-US-00010 Kit EnzChek ™ Elastase Assay (Molecular Probes) Protocol Based on the manufacturer’s protocol (for 200 μl per well) 1. Add 50 μl of A1AT standard or samples which ranges from 0.25 μM to 0.002 μM in final solution 2. Add 100 μl of 0.5 U/ml of pancreatic elastase (final concentration of 0.25 U/ml 3. Incubate at room temperature for 30 min 4. Add 50 μl of 100 μg/mL DQ elastin working solution (final concentration of 25 μg/mL) 5. Incubate at room temp for 30 min protected from light 6. Measure final fluorescence with excitation at 485 nm and emission at 530 nm Background 1. 150 μl of reaction buffer fluorescence 2. 50 μl of 100 μg/mL DQ elastin obtained with no-enzyme control Maximal 1. 50 μl of reaction buffer fluorescence 2. 100 μl of 0.5 U/ml of pancreatic elastase obtained in 2. 50 μl of 100 μg/mL DQ elastin absence of inhibitor
Residual Host Cell Proteins ELISA
[0213]
TABLE-US-00011 Kit CHO Host Cell Proteins 3rd Generation (Cygnus Technologies) Protocol Based on the manufacturer’s protocol 1. Add 50 μl of standards and sample 2. Add 100 μl of anti-CHO:HRP 3. Incubate at room temperature for 2 h and shake at 250 rpm 4. Wash each well with wash solution 5. Add 100 μl of TMB substrate 6. Incubate 30 min at room temperature 7. Measure final absorbance at 450/650 nm.
Residual DNA
[0214]
TABLE-US-00012 Protein 1. In a 0.2 ml PCR tube, add 160 μl of sample, 1.6 μl of proteinase K, digestion 6.4 μl of MilliQ water and 8 μl of 10% v/v SDS 2. Incubate 16 h at 50° C. 3. incubate for 10 min at 95° C. DNA Kit QIAamp viral RNA Mini Kit extraction (without addition of carrier RNA) (QIAGEN) Protocol Based on the manufacturer’s protocol 1. In 1.5 μl tube, add 560 μl of Buffer AVL without carrier RNA into a 1.5 ml tube and 140 μl of digested sample 2. Incubate at room temperature for 10 min 3. Add 560 μl of isopropanol and incubate for another 10 min 4. Pipet 630 μl of mixture to the QIAamp Mini column and centrifuge at 14,000 rpm for 1 min; repeat this step once 5. Add 500 μl of Buffer AW1 and centrifuge at 14,000 rpm for 1 min 6. Add 500 μl of Buffer AW2 and centrifuge twice at 14,000 rpm for 3 min 7. Add 40 μl of MilliQ water and centrifuge at 14,000 rpm for 1 min; repeat this step once DNA Kit Quant-iT ™ PicoGreen ™ dsDNA Assay Kit quantification (Molecular Probes) Protocol Based on the manufacturer's protocol 1. Add 100μl of standard with concentration of 50, 5, 0.5, 0.05 ng/ml and diluted sample 2. Add 100 μl of diluted PicoGreen reagent 3. Measure final fluorescence with excitation at 502 nm and emission at 523 nm
Example 1—Unconventional Behaviour of Anion Exchange Resin, TOYOPEARL NH2 750F
Example 1.1 Abnormal Behaviour of TOYOPEARL NH2 750F With Other Anion Exchange Resins
[0215] In this example, the use of various anion exchangers as a potential first flow-through column was examined. The experimental protocol is set out in the table below.
TABLE-US-00013 Experimental protocol Method High throughput screening (refer to the materials and methods section above) 70 μl of filtered cell culture supernatant (FCCS) (pH7.0, 13.43 m5/cm) containing 2.13 mg/ml of A1AT with a purity of 29.65% (by HPLC-SEC) was loaded to each well containing different types of anion exchange resins. With 60 min incubation time. Purpose To identify the performance for different types of anion exchanger Equilibration 50 mM Tris pH 8.2 buffer Wash buffer 50 mM Tris pH 8.2 Elution buffer 50 mM Tris pH 8.2 0.5 M NaCl Starting material 70 μl of filtered cell culture supernatant (FCCS) (pH7.0, 13.43 mS/cm) containing 2.13 mg/ml of A1AT with a purity of 29.65% (by HPLC-SEC) Evaluation Eluate of each condition was tested using HPLC-SEC for A1AT quantification
[0216] The results are shown in
[0217] In general, at a binding condition with pH greater than pl of A1AT (pH 5.3), an anion exchanger is able to capture A1AT from filtered cell culture supernatant (FCCS). As FCCS has a high conductivity of 13.43 mS/cm, conventional anion exchanger such as TOYOPEARL SuperQ-650 M did not have significant binding to A1AT as conductivity is required to be equal or less than 5 mS/cm. In contrast, the high salt-tolerant anion exchangers, HyperCel Star AX and Poros XQ, were able to bind 71.92 μg and 54.7 μg of A1AT for 5 μl of resin respectively.
[0218] However, TOYOPEARL NH2-750F did not follow the trend expected for high salt-tolerant anion exchanger. At a condition suitable for anion exchanger to operate in bind & eluate mode, TOYOPEARL NH2 750F surprisingly showed a binding capacity that was even lower than conventional, non-high salt-tolerant anion exchanger. It only captured 7.70 μg of A1AT as compared to 9.00 μg by TOYOPEARL SuperQ-650 M.
Example 1.2 Performance of TOYOPEARL NH2 750F at Different Binding Conditions
[0219] An investigation was next carried out to determine whether the performance of TOYOPEARL NH2-750F is affected by conditions such as pH and conductivity. The experimental protocol is set out in the table below.
TABLE-US-00014 Experimental protocol Method High throughput screening (refer to the materials and methods section above) Concentrated FCCS was spiked into each type of equilibration buffer to create 2.00 mg/ml in various binding conditions. Subsequently, 150 μl of FCCS with a purity of 63.22% (by HPLC-SEC) was loaded into respective wells with 120 min incubation time. Independent variables a) Loading amount/volume per ml of resin b) Loading pH and conductivity Fixed variable a) Loading amount/volume per ml of resin b) Quality of starting material c) Type of resin: NH2 750F Dependent variable a) Purity b) Static binding capacity per ul of resin (SBC) DoE Central composite face design consisted of a full factorial design and 2 center points (3 .sup.∧ + 2 = 11 points) Purpose To determine the performance of TOYOPEARL NH2 750F at different binding conditions of pH and conductivity Equilibration 50 mM MES pH6.0, 50 mM HEPES pH7.5 or 50 mM pH9.0 buffer Conductivity adjusted to 5, 10 or 15 mS/cm Starting material FCCS in various binding condition at a concentration of 2.00 mg/ml and 63.22% purity. Evaluation Flow-through of each condition was tested using HPLC-SEC for A1AT quantification and purity. Static binding capacity was calculated from the amount of A1AT in flow-through subtracted from the amount of A1AT loaded per μl of TOYOPEARL NH2 750F
The results are shown in Table 8 below and
TABLE-US-00015 TABLE 8 CCF Factors and response to evaluate the performance of TOYOPEARL NH2 750F at different binding conditions in terms of pH and conductivity TOYOPEARL NH2 750F Response Static Factors Binding Cond Purity Capacity pH mS/cm % μg/μl 6.0 5 96.22 10.70 6.0 10 93.81 11.72 6.0 15 93.57 4.81 7.5 5 94.12 25.01 7.5 10 92.28 8.39 7.5 15 92.65 10.48 9.0 5 91.15 7.98 9.0 10 86.38 4.08 9.0 15 85.05 0.46 7.5 10 92.82 12.30 7.5 10 93.06 11.19
[0220] TOYOPEARL NH2 750F showed insignificant static binding capacities of 2 to 14 μg A1AT per μl of resin at a pH condition ranging from pH 6.0 to 9.0 with conductivity ranging from 5 mS/cm to 15 mS/cm. Even at favourable conditions of high pH 7.25 and low conductivity of 5 mS/cm, TOYOPEARL NH2-750F showed an inability to bind A1AT, with an observed static binding capacity of 14 μg A1AT/μl resin. Nevertheless, it was effective in removing aggregates, giving an improvement of A1AT purity from 63.22% to 85% or to 95% depending on the binding conditions for pH ranging from 6.0 to 9.0 and conductivity below 15 mS/cm. Hence, TOYOPEARL NH2 750F is considered to operate in pseudo flow-through mode in the range of condition suggested.
[0221] In this example, conductivity below 5 mS/cm was not tested, but it is expected to give a comparable performance as that of 5 mS/cm based on the understanding of the behaviour of ion-exchange chromatography. Binding capacity is expected to increase with decreasing conductivity; thus, the resin is expected to still be effective in binding impurities at conductivity less than 5 mS/cm. The prediction given by modelling in MODDE also agrees with this assumption (see Table 9 below).
TABLE-US-00016 TABLE 9 Prediction for the performance of TOYOPEARL NH2-750F by MODDE Static Conduc- Pu- Binding tivity rity Lower Upper Capacity Lower Upper pH mS/cm % % % μg/μl μg/μl μg/μl Comparing 5 mS/cm with lower conductivity of 4 mS/cm which was not tested 6.0 5 96.24 94.30 98.17 11.92 8.19 15.66 6.0 4 96.58 94.50 98.65 12.49 8.45 16.54 7.5 5 94.69 93.03 96.35 14.15 10.29 18.01 7.5 4 95.03 93.21 96.85 14.72 10.50 18.94 9.0 5 89.23 87.29 91.17 7.02 3.28 10.76 9.0 4 89.57 87.50 91.65 7.59 3.54 11.63
Example 1.3 Breakthrough Curve of TOYOPEARL NH2-750F
[0222] As TOYOPEARL NH2 750F had limited ability to bind A1AT but was efficient in binding aggregates, further investigation was done to determine the impact of loading amount, flow rate and the quality of starting material. The experimental protocol is set out below.
TABLE-US-00017 Experimental protocol Method Chromatography instrumentation and operation (refer to the materials and methods section above) Using conventional batch mode with a single column connected to a column valve Independent variables a) Loading amount/ volume per ml of resin b) Flow rate c) Quality of starting material Fixed variable a) pH and conductivity: pH8.2 10 mS/cm b) Type of resin: NH2 750F Dependent variable a) HMW % which relates to purity b) Recovery which relates to binding of NH2 750F (i.e., higher binding -> greater loss at A1AT -> lower recovery) Purpose To determine the performance of TOYOPEARL NH2 750F in high molecule weight protein (HMW) removal and recovery using different starting material and different flowrate Column 1.0 ml of Toyopearl NH2-750F packed in Tricorn 5/50 column Equilibration 50 mM Tris pH 8.2 10 mS/cm (75 mM NaCl) buffer Starting Filtered cell culture supernatant (FCCS) containing material approximately 0.5 mg/ml of A1AT with HMW > 40% Clarified cell culture supernatant (FCCS-AC) containing approximately 0.5 mg/ml of A1AT with HMW > 25% Evaluation Flow-through of each condition was tested using HPLC-SEC for A1AT quantification and purity quantification
[0223] The results are shown in
[0224] In general, a trade-off relationship was observed between A1AT recovery and A1AT purity for experiments done using both FCCS and FCCS-AC as starting material. At low loading volume, more binding sites were available to capture the impurities in the supernatant. In the meantime, being an anion exchange resin, TOYOPEARL NH2 750F would also bind to A1AT concurrently, resulting in low A1AT recovery. However, with increasing loading amount per ml of resin, the loss of A1AT became less significant, but the purity of A1AT was compromised. Hence, TOYOPEARL NH2 750F is considered to operate in pseudo flow-through mode at high loading volume.
[0225] Particularly for FCCS-AC, TOYOPEARL NH2 750F was able to purify a greater amount per ml of resin as compared to FCCS in flow-through mode. This is reasonable as a certain amount of impurities had been removed during activated charcoal treatment.
[0226] Depending on the purpose of purification, the requirement of purity and tolerance of process loss may differ. In the context of a capture step which prioritises recovery over purity, conditions which yield moderate or even low purity will be sufficient. For instance, to keep HMW 1.0 ml of TOYOPEARL NH2 750F could handle up to 22 mg of FCCS with a maximal recovery of 88.0% or 53 mg of FCCS-AC with a maximal recovery of 90.5%. On the other hand, if this method is implemented in polishing step or in the situation that no subsequent purification step will be conducted, high or moderate purity will be recommended to maximise purity within this unit operation. For instance, to keep HMW≤0.1%, the column should not be loaded with more than 12 mg of FCCS or 24 mg of FCCS-AC. This is summarized in Table 10 below.
TABLE-US-00018 TABLE 10 Process evaluation of various process conditions Amount of A1AT Corresponding in FCCS per ml recovery Purity requirement of resin (mg) (%) High purity (HMW ≤ 0.1%) ≤12 ≤72.0 Moderate purity (HMW ≤ 1.0%) ≤22 ≤88.0 Low purity (HMW ≤ 10.0%) ≤42 ≤95.5 Amount of A1AT Corresponding in FCCS-AC per recovery Purity requirement ml of resin (mg) (%) High purity (HMW ≤ 0.1%) ≤24 ≤83.0 Moderate purity (HMW ≤ 1.0%) ≤53 ≤90.5 Low purity (HMW ≤ 10.0%) ≤80 ≤93.5
Validation of moderate and low purity process conditions was further explained in Example 3.
Example 2—Static Binding Capacity (SBC) of Anion Exchange Resins, TOYOPEARL SuperQ-650 M, HyperCel STAR AX & Poros XQ
[0227] Since the capture step focuses on sample volume reduction, a binding & eluate column is determined to be a reasonable choice to be connected in series with a first flow-through column. Furthermore, bind & eluate chromatography also helps to separate the target protein from media components. Example 2 explained how process parameters such as pH and conductivity will affect the binding capacity of various anion exchangers operated in bind & elute mode.
TABLE-US-00019 Experimental protocol Method High throughput screening (refer to the materials and methods section above) Purified A1AT was concentrated and spiked into each type of equilibration buffer to create 5.00 mg/ml in various binding conditions. Subsequently, 150 μl or 300 μl of purified A1AT was loaded to respective wells with 120 min incubation time. Independent variables a) Loading pH and conductivity b) Type of resin Fixed variables a) Loading amount/ volume per ml of resin b) Quality of starting material Dependent variable a) Static binding capacity per μl of resin (SBC) DoE Central composite face design consisted of a full factorial design and 2 center points (3{circumflex over ( )}2 + 2 = 11 points) For all resins, pH ranged from pH6.0 to 9.0 For conventional anion exchanger, TOYOPEARL SuperQ- 650 M, lower conductivity ranged from 4 to 10 mS/cm For high salt tolerance anion exchangers, HyperCel STAR AX and Poros XQ, higher conductivity ranged from 5 to 15 mS/cm Purpose To determine the binding capacity of different resins at various loading condition Starting 150 μl of purified A1AT at 5 mg/ml with 97.43% purity material was added to each well containing TOYOPEARL SuperQ-650 M or Poros XQ 300 μl of purified A1AT at 5 mg/ml with 97.43% purity was added to each well containing HyperCel STAR AX Evaluation Eluate of each condition was tested using HPLC-SEC for A1AT quantification to determine the static binding capacity
The results are shown in
TABLE-US-00020 TABLE 11 CCF Factors and response to evaluate the performance of anion exchangers at different binding conditions in terms of pH and conductivity a) TOYOPEARL SuperQ-650 M b) HyperCel STAR AX c) Poros XQ Factors Response Factors Response Factors Response Cond SBC Cond SBC Cond SBC pH mS/cm μg/μl pH mS/cm μg/μl pH mS/cm μg/μl 6.0 4 27.75 6.0 5 112.49 6.0 5 27.53 6.0 7 3.27 6.0 10 69.73 6.0 10 2.13 6.0 10 0.00 6.0 15 24.44 6.0 15 0.00 7.5 4 63.72 7.5 5 158.28 7.5 5 100.38 7.5 7 27.86 7.5 10 130.92 7.5 10 39.15 7.5 10 3.85 7.5 15 76.81 7.5 15 2.98 9.0 4 86.42 9.0 5 152.15 9.0 5 161.39 9.0 7 54.62 9.0 10 125.30 9.0 10 86.60 9.0 10 23.00 9.0 15 67.11 9.0 15 23.83 7.5 7 23.75 7.5 10 118.29 7.5 10 44.02 7.5 7 24.43 7.5 10 119.23 7.5 10 44.56
[0228] As shown in
[0229] In this example, conductivity below 4 mS/cm for conventional anion exchanger or 5 mS/cm for high salt-tolerant anion exchanger was not tested. However, conductivity below 4 mS/cm is expected to give a comparable performance as that of 4 mS/cm or 5 mS/cm based on the understanding of the behaviour of ion-exchange chromatography. Binding capacity is expected to increase with decreasing conductivity; thus, the resin is expected to be still effective in binding A1AT at conductivity less than 4 mS/cm or 5 mS/cm. The prediction given by modelling in MODDE also agrees with this assumption (see Table 12 below)
TABLE-US-00021 TABLE 12 Prediction for the performance of TOYOPEARL SuperQ-650 M, HyperCel STAR AX, Poros XQ by MODDE Static Binding Conductivity Capacity Lower Upper pH mS/cm μg/μl μg/μl μg/μl Comparing of 4 mS/cm or 5 mS/cm with lower conductivity of 3 mS/cm or 4 mS/cm which was not tested TOYOPEARL 6.0 4 24.87 12.65 37.09 SuperQ-650 M 6.0 3 30.29 15.42 45.16 7.5 4 55.96 48.41 63.51 7.5 3 64.35 55.09 73.61 9.0 4 87.05 74.83 99.27 9.0 3 98.41 83.54 113.28 HyperCel 6.0 5 111.31 100.22 122.40 STAR AX 6.0 4 119.80 107.92 131.67 7.5 5 163.13 153.64 172.63 7.5 4 171.62 161.21 182.02 9.0 5 157.28 146.19 168.37 9.0 4 165.77 153.89 177.64 Poros XQ 6.0 5 24.30 10.58 38.01 6.0 4 27.54 12.07 43.01 7.5 5 92.16 83.69 100.64 7.5 4 100.91 91.30 110.52 9.0 5 160.03 146.31 173.75 9.0 4 174.28 158.81 189.75
[0230] Unlike affinity resin, the binding capacity of anion exchange resin was found to be affected by pH and conductivity. This example provides an indication of the appropriate working range of TOYOPEARL SuperQ-650 M, HyperCel STAR AX and Poros XQ.
Example 3—Purification of Filtered Cell Culture Supernatant (FCCS) and Clarified FCCS (FCCS-AC) Using TOYOPEARL NH2 750F in Series with HyperCel Star AX
[0231] Example 3 examines how process parameters such as loading amount and quality of starting material may affect performance when using TOYOPEARL NH2 750F in series with HyperCel STAR AX. The experimental protocol is set out in the table below.
TABLE-US-00022 Experimental protocol Method Chromatography instrumentation and operation (refer to the materials and methods section above) Using a tandem column configuration with the first column connected to an injection valve and the second column connected to a column valve Independent variables a) Quality of starting material b) Loading amount/ volume per ml of resin Fixed variable a) Type of resin: TOYOPEARL NH2 750F & HyperCel STAR AX b) Loading pH & conductivity Dependent variables a) Recovery b) Purity Purpose To evaluate the performance of tandem column configuration using different starting material and different volume of TOYOPEARL NH2-750F Evaluation Eluate of each experiment was tested on SEC-HPLC and residual HCP ELISA
Table 13 below summarizes the different configurations used.
TABLE-US-00023 TABLE 13 Experimental conditions for various configuration of tandem chromatography FCCS Valve: Name of column (size) Experimental conditions Injection valve: Equilibration 50 mM Tris pH 8.2 #1 TOYOPEARL NH2- buffer 10 mS/cm 750F (0.6 ml) (75 mM NaCl) or Wash 50 mM Tris pH 8.2 #2 TOYOPEARL NH2- buffer 10 mS/cm 750F (1.0 ml) (75 mM NaCl) Column valve: Elution 10CV gradient elution HyperCel STAR AX buffer to 50 mM Tris pH 8.2 (1.0 ml) 1M NaCl Flowrate 0.5 ml/min Sample ~20 mg filtered cell culture supernatant (FCCS) titrated to pH 8.2 10 mS/cm Injection valve: Equilibration 50 mM Tris pH 8.2 #3 TOYOPEARL NH2- buffer 10 mS/cm 750F (0.3 ml) (75 mM NaCl) or Wash 50 mM Tris pH 8.2 #4 TOYOPEARL NH2- buffer 10 mS/cm 750F (0.6 ml) (75 mM NaCl) Column valve: Elution 10CV gradient elution HyperCel STAR buffer to 50 mM Tris pH 8.2 AX (1.0 ml) 1M NaCl Flowrate 0.5 ml/min Sample ~20 mg clarified cell culture supernatant (FCCS-AC) titrated to pH 8.2 10 mS/cm
The results are shown in Table 14 and
TABLE-US-00024 TABLE 14 Purification table of for various configuration of tandem chromatography FCCS or FCCS-AC HCP removal A1AT Conc HMW Monomer LMW Vol A1AT Recovery HCP Fold mg/ml % % % ml mg % ppm reduction Filtered cell culture 1.68 47.98 41.66 10.36 240,061 supernatant (FCCS) Purified sample from 3.72 6.34 89.82 3.83 6.15 22.90 100.54 42,035 5.71 Experiment #1 (0.6 ml TOYOPEARL NH2-750F) Purified sample from 4.51 1.44 98.18 0.38 4.30 19.40 88.18 33,982 7.06 Experiment #2 (1.0 ml TOYOPEARL NH2-750F) Clarified cell culture 0.80 11.57 88.43 0 89.33 10,172 supernatant (FCCS-AC) Purified sample from 4.82 1.40 98.60 0 3.87 18.66 87.02 421 24.15 Experiment #3 (0.3 ml TOYOPEARL NH2-750F) Purified sample from 5.13 0.39 99.61 0 3.57 18.31 84.79 352 28.89 Experiment #4 (0.5 ml TOYOPEARL NH2-750F)
[0232] With single unit operation using 0.6 ml of TOYOPEARL NH2 750F (i.e. 37.97 mg A1AT/ml resin) in series with 1.0 ml of HyperCel STAR AX to purify FCCS, the purity of eluate improved from 41.66% to 89.82% and residual HCP reduction from 240,061 ppm to 42,035 ppm. When the volume of TOYOPEARL NH2 750F increased to 1.0 ml (i.e. 22.00 mg A1AT/ml resin), the eluate had higher purity of 98.18% and residual HCP of 33,982 ppm. However, the recovery dropped from 100.54% to 88.18%, which correlated to the conclusion drawn from Example 1.
[0233] The tandem column configuration was also effective when applied to FCCS-AC. With single unit operation using 0.3 ml of TOYOPEARL NH2 750F (i.e. 71.46 mg A1AT/ml resin) in series with 1.0 ml of HyperCel STAR AX, the purity of eluate improved from 88.43% to 98.60% and residual HCP reduction from 10,172 ppm to 421 ppm. When the volume of TOYOPEARL NH2 750F increased to 0.5 ml (i.e. 43.19 mg A1AT/ml resin), the eluate had higher purity of 99.61% and residual HCP of 351 ppm. Similarly, the recovery decreased from 87.02% to 84.79%.
[0234] Chromatographs of HPLC-SEC were summarized on
Example 4—Purification of Filtered Cell Culture Supernatant (FCCS) and Clarified FCCS (FCCS-AC) Using Different Combinations of Tandem Columns
[0235] Example 4 explores different potential combinations of tandem columns. In particular, the application of conventional anion exchange resin (TOYOPEARL SuperQ-650 M), high salt-tolerant anion exchange resin (HyperCel STAR AX & Poros XQ) or affinity resin (Alpha-1 Antitrypsin Select) as second chromatography column was studied. The experimental protocol is set out in the table below.
TABLE-US-00025 Experimental protocol Method Chromatography instrumentation and operation (refer to the materials and methods section above) Using a tandem column configuration with the first column connected to the injection valve and the second column connected to the column valve Purpose To evaluate the performance of tandem column configuration using different selections of the second column Evaluation Eluate of each experiment was tested on SEC-HPLC and residual HCP ELISA and DNA assay
[0236] FCCS with pH 7.0 at 13 mS/cm and FCCS-AC with pH 7.0 at 10 mS/cm were used. Therefore, in this example, 5.0 mS/cm was further validated for TOYOPEARL SuperQ-650 M to minimise sample dilution while maximising binding capacity at pH9.0. As dilution of the sample would increase processing time in the sample application phase, minimal sample dilution is preferred. Similarly, 10 mS/cm was validated for high salt-tolerant anion exchangers with optimal pH8.2 for HyperCel STAR AX and pH9.0 for Poros XQ. Nevertheless, it is understood that the operating condition is not limited to the validated conditions.
[0237] Based on modelling done in Example 1 and 2, a prediction was made to evaluate the suitability of the selected conditions. As summarized in Tables 15 and 16 below, the selected condition was able to achieve purity above 85%. In addition, the static binding capacity of TOYOPEARL NH2 750F was significantly lower than that of TOYOPEARL SuperQ-650 M, HyperCel STAR AX and Poros XQ. Hence, the process loss of A1AT would be minimized.
TABLE-US-00026 TABLE 15 Prediction of TOYOPEARL NH2 750F as first chromatography column operated in flow-through mode based on modelling done in Example 1.2 Static Conduc- Pu- Binding tivity rity Lower Upper Capacity Lower Upper pH mS/cm % % % μg/μl μg/μl μg/μl 9.0 5 89.23 87.29 91.17 7.02 3.28 10.76 8.2 10 90.93 89.81 92.04 9.14 6.84 11.44 9.0 10 87.53 85.95 89.11 4.17 1.24 7.10 7.4 10 93.21 91.99 94.43 11.45 8.85 14.04
TABLE-US-00027 TABLE 16 Prediction of TOYOPEARL SuperQ-650 M, HyperCel STAR AX or Poros XQ as second chromatography column operated in bind & elute mode based on modelling done in Example 2 Static Binding Conductivity Capacity Lower Upper pH mS/cm μg/μl μg/μl μg/μl TOYOPEARL 9.0 5 75.69 65.78 85.59 SuperQ-650 M HyperCel 8.2 10 125.15 118.75 131.55 STAR AX Poros XQ 9.0 10 88.78 80.30 97.25
As the static mode is representative of dynamic mode to a limited extent, further validation was done based on the condition listed in Table 17 below.
TABLE-US-00028 TABLE 17 Experimental conditions for various combination of tandem chromatography FCCS or FCCS-AC Valve: Name of column (size) Experimental conditions Injection valve: Equilibration 50 mM Tris pH 8.2 #1 TOYOPEARL NH2-750F buffer 10 mS/cm (1.0 ml) for FCCS (75 mM NaCl) or Wash 50 mM Tris pH 8.2 #4 TOYOPEARL NH2-750F buffer 10 mS/cm (0.5 ml) for FCCS-AC (75 mM NaCl) Column valve: Elution 10CV gradient elution HyperCel STAR AX (1 ml) buffer to 50 mM Tris pH 8.2 1M NaCl Flowrate 0.5 ml/min Sample ~20 mg FCCS or FCCS- AC titrated to pH 8.2 10 mS/cm Injection valve: Equilibration 50 mM Tris pH 9.0 #2 TOYOPEARL NH2-750F buffer 5 mS/cm (1.0 ml) for FCCS (30 mM NaCl) or Wash 50 mM Tris pH 9.0 #5 TOYOPEARL NH2-750F buffer 5 mS/cm (0.5 ml) for FCCS-AC (30 mM NaCl) Column valve: Elution 10CV gradient elution TOYOPEARL SuperQ- buffer to 50 mM Tris pH 9.0 650 M (1 ml) 1M NaCl Flowrate 0.5 ml/min Sample ~20 mg FCCS or FCCS- AC titrated to pH 9.0 5 mS/cm Injection valve: Equilibration 50 mM Tris pH 9.0 #3 TOYOPEARL NH2-750F buffer 10 mS/cm (1.0 ml) for FCCS (75 mM NaCl) or Wash 50 mM Tris pH 9.2 #6 TOYOPEARL NH2-750F buffer 10 mS/cm (0.5 ml) for FCCS-AC (75 mM NaCl) Column valve: Elution 10CV gradient elution Poros XQ (1 ml) buffer to 50 mM Tris pH 9.0 1M NaCl Flowrate 0.5 ml/min Sample ~20 mg FCCS or FCCS- AC titrated to pH 9.0 10 mS/cm Injection valve: Equilibration 20 mM Tris pH 7.4 #4 TOYOPEARL NH2-750F buffer 10 mS/cm (1.0 ml) for FCCS (75 mM NaCl) or Wash 50 mM Tris pH 7.4 #8 TOYOPEARL NH2-750F buffer 10 mS/cm (0.5 ml) for FCCS-AC (75 mM NaCl) Column valve: Elution 10CV gradient elution Alpha-1 Antitrypsin Select buffer to 2 mM Tris pH 7.4 (4 ml) 2M MgCl2 Flowrate 0.5 ml/min Sample ~20 mg FCCS or FCCS- AC titrated to pH 7.4 10 mS/cm
The results are shown in Table 18 and
TABLE-US-00029 TABLE 18 Purification table for various combination of tandem chromatography FCCS or FCCS-AC HCP DNA removal removal A1AT Conc HMW Monomer LMW Vol A1AT Recovery HCP Fold DNA Fold mg/ml % % % ml mg % ppm reduction ppb reduction Filtered cell 2.01 28.30 56.13 15.58 207,297 1,848,783 culture supernatant (FCCS) Purified sample 4.13 2.62 97.38 — 4.10 16.95 83.79 41,639 4.98 10,874 170.01 from Experiment #1 (HyperCel STAR AX) Purified sample 2.43 1.83 98.17 — 7.35 17.88 86.27 40,892 5.07 11,155 165.74 from Experiment #2 (TOYOPEARL SuperQ-650 M) Purified sample 3.55 15.27 84.41 0.32 5.50 19.54 96.23 37,513 5.53 36,924 50.07 from Experiment #3 (Poros XQ) Purified sample 1.49 0.62 99.38 — 11.81 17.54 86.80 811 255.56 32,771 56.41 from Experiment #4 (Alpha-1 Antitrypsin Select) Clarified cell 1.02 10.87 87.90 1.23 10,816 37,489 culture supernatant (FCCS-AC) Purified sample 4.86 0.34 99.66 — 3.65 17.75 83.64 427 25.35 2,059 18.21 from Experiment #5 (HyperCel STAR AX) Purified sample 4.05 0.23 99.77 — 3.53 14.31 75.64 486 22.25 2,745 13.66 from Experiment #6 (TOYOPEARL SuperQ-650 M) Purified sample 5.32 0.56 99.44 — 3.30 17.56 84.14 472 22.94 1,872 20.02 from Experiment #7 (Poros XQ) Purified sample 1.55 0.14 99.86 — 10.91 16.86 80.11 9 1235.13 7,968 4.71 from Experiment #8 (Alpha-1 Antitrypsin Select)
[0238] With the appropriate operating condition, tandem column configuration was able to work on different combinations of the second bind & elute columns such as HyperCel STAR AX, TOYOPEARL SuperQ-650 M, Poros XQ or Alpha-1 Antitrypsin Select. For conventional or high salt-tolerant anion exchanger, the operating conditions were selected based on the static binding capacity explained in Example 2. As for affinity chromatography, the conditions were based on the manufacturer's recommendation as it was less affected by pH and conductivity.
[0239] A1AT activity before and after purification was further determined by inhibition of pancreatic elastase. From
Example 5—Comparative Study 1: Effect of Tandem Column Configuration on Effective Dynamic Binding Capacity (DBC) of Anion Exchanger
[0240] The performance of a tandem column configuration was compared against that of single column configuration in this example. The experimental protocol is set out in the table below.
TABLE-US-00030 Experimental protocol Method Chromatography instrumentation and operation (refer to the materials and methods section above) Single column installed on column valve Or Using tandem column configuration with the first column connected to the injection valve and the second column connected to the column valve Purpose To evaluate the performance of tandem column configuration Evaluation Flowthrough of each condition was tested using HPLC- SEC for A1AT quantification and purity quantification
[0241] The experimental conditions used are laid out in Table 19 below.
TABLE-US-00031 TABLE 19 Experimental conditions for binding efficiency evaluation Valve: Name Configuration of column (size) Experimental conditions Single anion Column valve: Equilibration 50 mM Tris pH 8.2 exchange HyperCel STAR buffer 12.5 mS/cm column in AX (1 ml) (100 mM NaCl) conventional Flowrate 0.3 ml/min batch mode Tandem Injection valve: Equilibration 50 mM Tris pH 8.2 columns TOYOPEARL buffer 12.5 mS/cm NH2-750F (2 ml) (100 mM NaCl) Column valve: Flowrate 0.3 ml/min HyperCel STAR AX (1 ml)
[0242] The results are shown in
[0243] Typically, the dynamic binding capacity of anion exchanger is constant under the same binding condition. As discussed previously, anion exchange chromatography has low selectivity such that it will bind to negatively charged impurities such as host cell proteins and DNA. Pre-treatment to remove impurities by the first column in tandem configuration helps to fully utilise the binding sites in the second column to capture target protein. Therefore, a significant increase in effective binding capacity of target protein was achieved, resulting in improved productivity. From
[0244] To match the yield achieved by 1.0 ml TOYOPEARL NH2 720F and 1.0 ml HyperCel STAR AX, conventional batch mode with single column would require 3 cycles of 1.0 ml HyperCel STAR AX, 1 cycle of 3.0 ml HyperCel STAR AX or 1 cycle of 1.0 ml TOYOPEARL NH2 750F followed by 1 cycle of 1.0 ml HyperCel STAR AX. This will result in longer processing duration or higher consumable cost. In contrast, the tandem configuration has better utilisation of resin or shorter processing time with an amalgamation of 2 purification steps. Hence, this method would advantageously lead to higher productivity and reduction of production cost. The shortcomings of single column configuration against tandem column configuration are summarized in Table 20 below.
TABLE-US-00032 TABLE 20 Potential disadvantages of conventional batch mode process with a single column Conventional batch mode (To match Potential disadvantage with 1.0 ml TOYOPEARL NH2 720F as compared to the and 1.0 ml HyperCel STAR AX) present method 3 cycles of 1.0 ml HyperCel STAR AX Longer processing duration 1 cycle of 3.0 ml HyperCel STAR AX Higher consumable cost; May face hardware restriction when the largest column available is not sufficient to process 1 batch of drug 1 cycle of 1.0 ml TOYOPEARL NH2 Longer processing 750F followed by 1 cycle of 1.0 ml duration HyperCel STAR AX
Example 6—Comparative Study 2: Comparison With Conventional Purification Methods in a Single Unit Operation
[0245] In this example, a tandem configuration is further compared with a single column affinity chromatography using conventional batch mode and anion exchange chromatography using conventional batch mode. The experimental protocol is set out in the table below.
TABLE-US-00033 Experimental protocol Method Chromatography instrumentation and operation (refer to the materials and methods section above) Single column installed on column valve Or Using a tandem column configuration with the first column connected to the injection valve and the second column connected to the column valve Purpose To evaluate the performance of a single unit operation Evaluation Eluate of each condition was tested using HPLC-SEC for A1AT quantification and purity quantification and ELISA for residual HCP
[0246] The experimental conditions employed are laid out in Table 21 below.
TABLE-US-00034 TABLE 21 Experimental conditions for different configuration of single unit operation using FCCS Valve: Name of Experimental conditions and Configuration column (size) results Affinity Column valve: Equilibration 50 mM Tris pH chromatography Alpha-1 buffer 8.2 12.5 mS/cm (AC) using Antitrypsin (100 mM NaCl) conventional Select (1.0 ml) Elution 50 mM Tris pH batch mode buffer 8.2 2M MgCl2 Flowrate 0.3 ml/min Sample ~8 mg of filtered cell culture supernatant (FCCS) at pH 8.2 12.5 mS/cm Anion exchange Column valve: Equilibration 50 mM Tris pH chromatography HyperCel buffer 8.2 12.5 mS/cm (HC) using STAR AX (100 mM NaCl) conventional (1.0 ml) Elution 50 mM Tris pH batch mode buffer 8.2 1M NaCl Flowrate 0.3 ml/min Sample ~10 mg of filtered cell culture supernatant (FCCS) at pH 8.2 12.5 mS/cm Tandem column Injection valve: Equilibration 50 mM Tris pH using anion TOYOPEARL buffer 8.2 12.5 mS/cm exchange NH2-750F (100 mM NaCl) chromatography (2.0 ml) Elution 50 mM Tris pH (AXTC) Column valve: buffer 8.2 1M NaCl HyperCel Flowrate 0.3 ml/min STAR AX Sample ~30 mg of (1.0 ml) filtered cell culture supernatant (FCCS) at pH 8.2 12.5 mS/cm
[0247] The results are shown in Table 22 below, and
TABLE-US-00035 TABLE 22 Purification table of various configuration of single unit operation using FCCS HPC removal A1AT Conc HMW Monomer LMW Vol A1AT Recovery HCP Fold mg/ml % % % ml mg % ppm reduction Filtered cell 0.62 44.52 25.45 30.03 471,508 culture supernatant (FCCS) Affinity 1.96 23.88 74.46 1.66 2.42 4.74 58.9 3,777 124.85 chromatography (AC) Anion 0.79 22.93 66.02 11.04 13.00 10.32 101.1 106,942 4.41 exchange chromatography (HC) Tandem 4.56 4.02 94.22 1.76 6.00 27.38 90.7 88,513 5.33 column (AXTC)
[0248] A1AT can be purified using affinity chromatography or anion exchange chromatography. Although affinity chromatography exhibits high selectivity with only 3,777 ppm of residual HCP, the percentage of HMW remains high at 23.88% as it is inefficient in removing aggregated proteins, resulting in a low A1AT purity of 74.46%. For anion exchange chromatography with low selectivity, A1AT purity in the eluate was only 66.02% and the residual HCP was only removed by 4.41 folds. However, with tandem column configuration, A1AT purity was shown to improve to 94.22% with a further reduction of residual HCP to 88,513 ppm. Therefore, tandem column configuration is a solution to anion exchanges with low selectivity and a potential replacement of affinity chromatography.
[0249] The performances of the different configurations were further compared using clarified FCCS-AC as a starting material. The experimental conditions employed are laid out in Table 23 below.
TABLE-US-00036 TABLE 23 Experimental conditions for different configuration of single unit operation using FCCS-AC Valve: Name of Configuration column (size) Experimental conditions Affinity Column valve: Equilibration 50 mM Tris pH chromatography Alpha-1 buffer 8.2 12.5 mS/cm (AC) using Antitrypsin (100 mM NaCl) conventional Select (1.0 ml) Flowrate 0.3 ml/min batch mode Sample ~5 mg of clarified cell culture supernatant (FCCS-AC) at pH 8.2 12.5 mS/cm Anion exchange Column valve: Equilibration 50 mM Tris pH chromatography HyperCel ™ buffer 8.2 12.5 mS/cm (HC) using STAR AX (100 mM NaCl) conventional (1.0 ml) Elution 50 mM Tris pH batch mode buffer 8.2 1M NaCl Flowrate 0.3 ml/min Sample ~9 mg of clarified cell culture supernatant (FCCS-AC) at pH 8.2 12.5 mS/cm Tandem column Injection valve: Equilibration 50 mM Tris pH using anion TOYOPEARL buffer 8.2 12.5 mS/cm exchange NH2-750F (100 mM NaCl) chromatography (0.5 ml) Elution 50 mM Tris pH (AXTC) Column valve: buffer 8.2 1M NaCl HyperCel ™ Flowrate 0.3 ml/min STAR AX Sample ~14 mg of clarified (1.0 ml) cell culture supernatant (FCCS-AC) at pH 8.2 12.5 mS/cm
[0250] The results are shown in Table 24 below, and
TABLE-US-00037 TABLE 24 Purification table of various configuration of single unit operation using FCCS-AC HPC removal A1AT Conc HMW Monomer LMW Vol A1AT Recovery HCP Fold mg/ml % % % ml mg % ppm reduction Clarified cell 0.79 12.81 87.19 — 11,039 culture supernatant (FCCS-AC) Affinity 1.50 2.46 97.54 — 2.29 3.44 72.54 1,869 5.91 chromatography (AC) Anion 2.71 3.11 96.89 — 3.00 8.14 88.44 2,860 3.86 exchange chromatography (HC) Tandem 4.54 0.68 99.32 — 2.45 11.11 80.00 163 67.70 column (AXTC)
[0251] When FCCS-AC was used as the starting material, tandem column performed the best in both aggregate and HCP removal. The final purified sample had a purity of 99.32% with only 163 ppm of residual HCP, which could not be achieved using other modes of single unit operation.
[0252] Given the same process duration, tandem chromatography has proven to achieve the highest aggregate removal as compared to other process methods. Within a single unit operation, the tandem configuration was able to achieve 94.22% purity using filtered cell culture supernatant or 99.32% using clarified cell culture supernatant.
[0253] The examples demonstrate the direct capture and purification of recombinant Alpha-1 antitrypsin (A1AT) in CHO cell culture in accordance with embodiments of the methods. A high salt tolerant anion exchanger TOYOPEARL NH2 750F was found to exhibit abnormal performance in that it could not bind A1AT readily even under favourable conditions. Hence, it was treated as pseudo flow-through mode and positioned as the first column in tandem chromatography to remove/pre-capture undesirable impurities or components in the cell culture supernatant such as CHO host cell protein, HCP, DNA and aggregates. To avoid installation of an additional column valve, TOYOPEARL NH2-750F is connected to injection valve while a second anion exchanger column (e.g. HyperCel™ STAR AX) or affinity column (e.g. Alpha-1 Antitrypsin Select) is connected to column valve located downstream. The intermediate product from first column was transported instantaneously to the second column (operating in bind & elute chromatography) in line whereby A1AT was captured either by an anion exchange chromatography or affinity chromatography. Subsequently, the first column was bypassed while the captured A1AT was dissociated from the second column by an elution buffer/increasing the conductivity of buffer. Both columns can be regenerated under the same conditions. As a result, this process design led to an overall improvement of product purity and productivity in a single unit operation. In addition, the undesirable impurities or components did not bind to the second column, leaving more binding sites available for A1AT. Therefore, second column will have increased effective dynamic binding capacity of A1AT.
[0254] Example 1, 2 and 3 summarized the process design and optimization of tandem column chromatography while Example 4 explored on different potential combination of tandem column chromatography. This invention had proven to improve product purity significantly in a unit operation. For instance, using TOYOPEARL NH2 750F in series with HyperCel STAR AX, the monomer purity of A1AT had improved from 56.13% in filtered cell culture supernatant (FCCS) to 97.38% with a process recovery of 83.79% or 87.90% in clarified cell culture supernatant (FCCS-AC) to 99.66% with a process recovery of 83.64% (from Table 18). From comparative studies in Example 5 and 6, tandem column configuration was proved to improve the selectivity of anion exchange chromatography. the effective dynamic binding efficiency of HyperCel™ STAR AX was also demonstrated to increase from 11.67 mg to 32.08 mg of A1AT per ml of resin. In addition, tandem column configuration has the capability to achieve better product quality within the same process duration and conditions. Using filtered cell culture supernatant with 25.45% purity, tandem chromatography could produce A1AT with 94.22% purity as compared to 66.02% in single anion exchangers (from table 22).
[0255] Traditionally, protein purification is operated in batch mode with a single column used in each unit operation and first chromatographic step is preferred to bind & elute chromatography. Disclosed herein is a new approach to process development while maintaining key purification principles using existing hardware. Hence, it is applicable to different FPLC systems with the potential to scale up to manufacturing process. Furthermore, an amalgamation of flow-through and bind & elute chromatography in tandem configuration has been proven herein to enhance purity and productivity in a single step purification. When applied in the capture step, embodiments of the method are able to achieve >90% purity from a starting material of less than 50% purity in a single unit operation. Embodiments of the method may also be applicable to other target proteins or other selection of chromatographic resins.
[0256] Embodiments of the method are expected to be particularly beneficial for purification of target proteins, including acidic proteins, which presently depend on costly affinity resin or target proteins for which affinity resin is not available and presently rely on low-resolution purification methods. Embodiments of the method are therefore applicable to a wide range of target proteins with various combinations of chromatographic resin.
[0257] It will be appreciated by a person skilled in the art that other variations and/or modifications may be made to the embodiments disclosed herein without departing from the spirit or scope of the disclosure as broadly described. For example, in the description herein, features of different exemplary embodiments may be mixed, combined, interchanged, incorporated, adopted, modified, included etc. or the like across different exemplary embodiments. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.
APPLICATIONS
[0258] Embodiments of the method disclosed herein involve a tandem column configuration that can maximise process efficiency with improved productivity and product quality in single unit operation. Tandem column configuration can be achieved by connecting two columns in series without hardware modification, with first chromatography column installed at injection valve and second chromatography column installed at column valve. In the process condition whereby first column operated in flow-through chromatography and the second column operated in bind & elute chromatography, first column will remove impurities, to thereby allowing the second column to have more binding sites available for target protein (instead of impurities). As a result, embodiments of the method employing tandem chromatography are able to improve overall/enhance the selectivity, binding efficiency and productivity in a single step purification process.
[0259] Typically, an anion exchanger binds to any molecules with negative net surface charge, and thus, the process is not specific to any target proteins. Advantageously, embodiments of the method are able to improve the overall selectivity and binding efficiency of an anion exchanger. By connecting two anion exchanger columns in series, through direct capture and purification, embodiments of the method are demonstrated able to purify the acidic recombinant protein A1AT from a cell culture supernatant at high recovery and purity.
[0260] Embodiments of the method can advantageously capture target proteins with no or minimal dilution. Embodiments of the method using high salt tolerant anion exchanger can be advantageously applied to supernatant with conductivity greater than 10 mS/cm which is challenging for conventional anion exchanger that requires conductivity to be lower than 5 mS/cm.
[0261] Further, embodiments of the method use scalable chromatographic resin that allows the method to be applicable in the manufacturing scale.
[0262] In particular, embodiments of the method have demonstrated a capability to resolve current challenges faced in production of A1AT, such as low resolving capability of ion exchange in capture step, a small operating window use of conventional anion exchange as the ionic strength of binding buffer and sample has to be less than 5 mS/cm and costly affinity chromatography with high selectivity but low binding capacity.