Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_101_библиотеки_им_акад_М_И_Перельмана
.pdf
https://t.me/med1917
68
Trends in Recombinant Proteins Manufacturing
concentrated and washed with 5× volumes. Membranes of up to 3 m2 area that can process a volume
of 200 L/ (h m2) are available. Several single- use systems are available (SciLog, Millipore) for a
limited lter area (area of up to 2.5 m2), but larger systems (such as single- use modules and pumps)
might replace existing reusable systems with an area of 14 m2, as it is logical to carry out ltration
steps in a closed system.
Single- use TFF modules are available as ready- to- use cassettes to be used in TFF setups. These
systems provide quick turnaround times and more exibility. Single- use systems are available as
preassembled units with gamma- irradiated ow paths and sensors, thus reducing setup time. Presanitized pre- packaged cassettes are also another option as a single- use system. Cleaning a TFF
system and the cassette is an important step in downstream processing, particularly for multiproduct
use. It is essential to minimize cross- contamination risk while also ensuring that ux rates are well
maintained. Cleaning procedures, including those in dedicated systems for each product, must be
well validated to ensure no product carryover from previous batches. A completely single- use TFF
system can be built together with off- the- shelf components (including valves, sensors, and 2D
bags for liquids). Technology improvements and integration of single- use components can enable
automated single- use systems to be applied conveniently for large- scale manufacturing.
4.4.1 geneRal filtRation aPPlications
Generally, lters are rarely reused in the pharmaceutical industry, except for steel meshes in bulk
manufacturing of nonsterile dosage forms. Single- use lter devices in biological manufacturing
were the earliest forms that were used as single- use systems, mainly because of the problems related
to cleaning them; the cost of their parts has always been reasonable.
Numerous lter designs and mechanisms are being utilized within the biopharmaceutical
industry. Prelters are commonly pleated, and wound lter eeces are manufactured from meltblown random ber matrices. These lters are used to remove a higher amount of contaminant from
the uid. Prelters have a large band of retention ratings and can be optimized for all necessary
applications. The most common application for prelters is to protect membrane lters, which are
tighter and more selective than prelters. Membrane lters are used to purify or sterilize uids.
These lters need to be integrity testable to assess whether they meet the performance criteria.
Crossow ltration can be performed with micro- or ultraltration membranes. The uid sweeps
over the membrane layer and therefore keeps it unblocked. This ltration method allows dialtration
or concentration of uid streams.
Dead- end ltration is one of the simplest methods of lter operation. Dead- end ltration uses
the principle of passing a uid feed stream perpendicularly to a lter device at minimal pressure,
which is usually applied using a pump or as compressed gas pressure above the lter device. All
contaminants larger than the average pore size of the lter media are retained by the lter material,
thereby leading to lter blockage by plugging its channels or pores. The setup of dead- end ltration uses minimum accessories such as tubing/ piping, tanks, and controls. Dead- end lters involve
microporous membranes made of synthetic polymers such as polyethersulfone, polyamide, cyanoacrylate, and polyvinylidene uoride and are extensively used for sterile processing. They are used
for media ltration into sterile bags and containers, bioburden reduction during cell harvest clarication, chromatography column protection, and nal ltration of the puried bulk drug substance.
These lters are often attached to single- use bags and are pre- sterilized by gamma irradiation.
4.4.2 fill- finish oPeRations
Fill- nish, which is the nal processing step of drug substance and drug product, requires tight
control of aseptic operations without compromising sterility and integrity while ensuring safety and
efciency. As such, ll- nish operations typically require sophisticated equipment and technology.
https://t.me/med1917
Trends in Recombinant Proteins Manufacturing
FIGURE 4.3 Closed- system lling transfer set to isolator
Source: www.emdmi llip ore.com
69
The traditional ll- nish setup uses xed systems involving complex components that require extensive cleaning and sterilization, assembly, and disassembly. A time- pressure system and a piston
pump are widely used for dosing and lling operations. However, these systems require assembly
and validation of CIP and SIP to ensure the nal product meets the sterility specications. The
use of single- use components for these critical processes is more likely to ensure that the nal
product is not compromised while reducing cross- contamination risk. Additionally, SUT in ll-
nish operations can reduce the turnaround time between batches and increase exibility, particularly for a multiple product facility.
A traditional, xed system can adopt single- use solutions. Figure 4.3 presents a single- use llnish setup with installed hardware, hard- piped connections, and limited operational exibility.
This setup combined the expertise of Millipore in single- use uid- path management to ensure sterility and integrity of the operation.
Successful implementation of a single- use system is beyond assembling single- use components.
The use of suppliers with experience in validating such systems and understanding the manufacturer’s
requirements to integrate and offer customized solutions, ensure compatibility, and perform
assessments will be critical to the success of single- use implementation and assurance of sterility.
The exibility of SUT makes its use more relevant for single- and multi- product lling facilities,
thus increasing facility efciency and utilization due to the ease of installation, operation, and elimination of CIP/ SIP validation.
4.4.3 safety
Biologics manufacturers must comply with regulatory requirements. This includes, for instance,
ensuring that the supplier is reliable and can provide the necessary documentation supporting suitability (product contact material), qualication, and validation of the single- use systems to support
audits by the end- user. The end- user must have a user requirement specication and perform
technical evaluation with multiple vendors to determine suitability with their process. Single- use
components must be qualied together with the equipment for intended use. Additionally, these
components should be included in the process validation exercise.
https://t.me/med1917
70
Trends in Recombinant Proteins Manufacturing
Single- use devices make extensive use of plastic materials or elastomer systems, starting from
lter housings to the lining of bioreactors. Today, perhaps the most signicant impediment in the
wider acceptance of single- use systems is the controversy surrounding the possibility of contamination of the product with chemicals from the plastic lm. All nal containers and closures should be
made of a material that does not hasten the product’s deterioration or otherwise render it less suitable
for the intended use (Biologics 21CFR600.11(h)).
Regulatory requirements pertain to the toxic effects of leachables, and risk to biological drugs
arises based on the effect of leachables on the 3D and 4D structure of protein drugs. Such changes
can render the drug more immunogenic if not less effective, and these side effects are, thus, of
greater importance to the bioprocessing industry. Leachables refer to chemicals migrating from
single- use processing equipment to various components of the drug product during manufacturing. Extractables are chemical entities (both organic and inorganic) extracted from single- use
components using common laboratory solvents during controlled experiments. They represent the
worst- case scenario and predict the types of leachables that may be encountered during biopharmaceutical production. Leaching is specic not only to plastics but also to chemicals from stainless
steel. Stainless steel, commonly used in biopharmaceutical applications, is of grade 316L and is an
alloy containing mainly iron, nickel, and chromium, with minor amounts of manganese and vanadium. Stainless steel is a signicant source of metal leachables, especially if the surface of the
equipment or tank is not properly treated. The main leachable components are iron, chromium, and
nickel. Several fold higher concentrations of metals such as iron and nickel leach into the liquid formulation after storage at room temperature in un- passivated stainless- steel vessels compared with
passivated stainless- steel vessels.
4.4.4 PolyMeRs and additives
The materials used to fabricate single- use processing equipment for biopharmaceutical manufacturing are usually polymers, such as plastic or elastomers (rubber), rather than the traditional
materials (metal or glass). Polymers offer more versatility because they are lightweight, exible, and
much more durable than their traditional counterparts. Plastic and rubber are single- use components,
and their use eliminates cleaning validation. Additives can also be incorporated into polymers to
clarify glass or to add color to labels or code parts. Polymer degradation can be controlled with the
use of additives (stabilizers).
When a plastic resin is processed, it is often introduced into an extruder, wherein it is melted
at high temperatures, and its stability is inuenced by its molecular structure, the polymerization
process, the presence of residual catalysts, and the nishing steps used in production. Processing
conditions during extrusion (e.g., temperature, shear, and residence time in the extruder) can signicantly affect polymer degradation. End- use conditions that expose a polymer to excessive heat or
light (such as outdoor applications or sterilization techniques used in medical practices) can foster
premature failure of polymer products, leading to loss of exibility or strength. If left unchecked,
the process can often result in total failure of the plastic component.
The complexity of chemical reactions involved in the manufacturing of plastics inuences the
presence of extractables and leachables, making the process very complex and challenging. When
testing for extractables and leachables, lesser- known minor chemical species may be the ones that
leach into a drug product, but this is not predictable, as it is, to a greater degree, a function of
the product’s characteristics. All byproducts of the polymer and additives (stabilizers, llers, and
elastomers) become available to leach from polymers into a drug product.
Despite the risk involved in using additives added to polymers, the utility of polymers in singleuse bioprocess equipment (and in all medical or pharmaceutical applications) far outweigh the risks
associated with their use. These risks can be managed well through three steps: material selection,
implementing a proper testing program, and partnering with vendors.
https://t.me/med1917
Trends in Recombinant Proteins Manufacturing
TABLE 4.3
71
Summary of the Tests Carried Out and Results Obtained for a Plastic Film Used to Produce
Bioreactor Bags
Biocompatibility
USP Acute Systemic Injection Test Pass USP<88>
USP Intracutaneous Injection Test Pass USP<88>
USP Intramuscular Implantation Test Pass USP<88>
USP MEM Elution Method Non- cytotoxic USP<87>
Physiochemical Test for Plastics Pass USP <661>
Extractables
Physical Data
TOC after
90 days (ppm)
Puried Water (pH= 7) <2 –0.79
Acidic Water (pH<2) <3 + 0.01
Basic Water (pH>10) <4 + 0.87
Water Vapor Transmission Rate (g/ 100in2/ 24h) 0.017 ASTM F- 1249
Carbon Dioxide Transmission Rate (cc/ 100in2/ 24h) 0.129 ASTM F- 2476
Oxygen Transmission Rate (cc/ 100in²/ 24h) 0.023 ASTM F- 1927
Average
Force
Tensile 32.73 lbs 25110 psi 1084% ASTM D 882- 02
Min Force Average
Tear Resistance 6.77 Ibs 7.21 Ibs 7.74 Ibs ASTM D1004- 03
Puncture Resistance 16.42 Ibs 18.16 Ibs 19.51 Ibs FTMS 101C
Average
MOE
Force
Average
Elongation
Max Force
pH shift after
90 days
4.4.5 MateRial selection
The type of plastic used should match the required physical and chemical properties and compatibility of its additives. Ensuring compatibility with the drug product often reduces the amount of
material leaching that can occur. It is also important to select polymers and additives approved for
specic use by the regulatory authorities. Such compounds have already undergone a fair amount
of analytical and toxicological testing, and adequate information of these compounds is often available. Thus, most manufacturers are likely to continue using these additives, and accordingly, the user
does not alter the composition of these compounds at a later stage. The art of using polymers and
additives is likely to survive, obviating the need for a change control step, as signicant changes in
the process need to be reported back to the FDA.
Commercially supplied plastic lms are proprietary formulations and arrangements; for example,
Advanced Scientic produces bags made of two lms. The uid contact lm is made of 5.0- mm PE.
The outer covering is a ve- layer 7- mm co- extrusion lm, which provides barrier and durability.
A typical test report is presented in Table 4.3.
4.4.6 testing
Polymers used in medical and pharmaceutical applications should comply with the appropriate USP
guidelines, and it is recommended that these polymers meet USP Class VI testing, as documented
in USP 88. Appropriate extractable and leachable testing programs must be implemented for all
bioprocessing materials that directly come into contact with the drug.
https://t.me/med1917
72
Trends in Recombinant Proteins Manufacturing
Bio- Process Systems Alliance (https:// bpsa llia nce.org/ ) provides the best- practice guidelines for
conducting such testing as a two- part technical guideline for evaluating the risk associated with
extractables and leachables, specically for single- use processing equipment. This organization
encourages the use of single- use systems and provides excellent support and assistance; the reader
is highly encouraged to visit the website for newer information and participate in their seminars and
conventions to stay abreast of the developments in this fast- changing eld.
Testing for leachables does not end once the materials have been qualied. It is necessary to have
a quality control program rather than testing the product or equipment alone. The level of quality
control testing will depend on risk tolerance. Manufacturing of recombinant drugs involves extensive purication steps that are likely to remove most of these leachables. Additionally, the nal
medium used for protein solutions is aqueous, and many leachables are not soluble in water, further
reducing the risk. A greater risk is also attributed to the nal packaging components; for example,
rubber stoppers used in packaging the nal dosage form are more likely to cause risk to the protein formulation than any other component in the chain of a single- use drug that is exposed during
the manufacturing process. Biologics manufacturers need to work in association with suppliers to
ensure that regulatory requirements adhere to a product safety standpoint.
The DP of particulate matter should meet an important specication or testing requirement: visible and subvisible. Contamination of drug products with particulate matter is typically well controlled by ltration, and visual inspection is performed during lling. Single- use components must
also be manufactured under controlled conditions that can reduce particulate matter and reduce them
to a minimum in the nal product.
4.4.6.1 Regulatory Standards
There are no specic standards or guidelines that reference extractables and leachables from singleuse bioprocessing materials. Many references that do apply have been written to address processing
materials and equipment without regard to construction materials.
The United States and Canada
The foundation for the requirement to assess extractables and leachables in the United States
was introduced in Title 21 of the Code of Federal Regulations (CFR) Part 211.65, which states
that: “Equipment shall be constructed to surface that contact components, in- process materials,
or drug products shall not be reactive, additive, or absorptive to alter the safety, identity, strength,
quality, or purity of the drug product beyond the ofcial or other established requirements.”
This regulation applies to all materials, including metals, glass, and plastics. Extractables and
leachables would generally be considered an additive, although it is also possible for leachables to
interact with a product to yield new contaminants.
The US FDA regulatory guideline for nal container closure systems, although not written for
process contact materials, provides directions regarding the type of nal product testing that may be
provided regarding extractables and leachables from single- use process components and systems.
The guideline indicates the types of drug products and component dosage form interactions that the
FDA considers to be at the highest risk for extractables. Generally, the likelihood of the packaging
component interacting with the dosage form is highest in injectable dosage forms, mainly because
of the low level of leachables that can be allowed in such drug delivery systems.
Drugs intended to be injectables or inhalants will have higher levels of regulatory concern than
oral or topical drugs. Similarly, liquid dosage forms will have more serious regulatory concerns than
tablets because the leachates migrate into liquids more easily than into solids.
Additionally, pharmaceutical- grade materials are expected to meet or exceed industry and regulatory standards and requirements, for example, those listed in USP <87> and <88>. The USP
procedures test the biological reactivity of mammalian cell cultures following contact with polymeric
materials. However, they are not considered sufcient regulatory documentation for extractables and
https://t.me/med1917
Trends in Recombinant Proteins Manufacturing
73
leachables because many toxicological indicators are not evaluated, including subacute and chronic
toxicity, especially an evaluation of carcinogenic, reproductive, developmental, neurological, and
immunological effects.
The European Union
A statement related to the US 21 CFR 211.65 is found in the rules governing the manufacture of
medicinal products in the European Union (EU). The EU, a useful manufacturing practice document, states, “Production equipment should not present any hazard to the products.” “The parts of
the production equipment that come into contact with the product must not be reactive, additive, or
absorptive to such an extent that it will affect the quality of the product and thus present any hazard.”
The EMEA published a guideline on immediate plastic packaging materials (www.ema.eur opa.
eu/ en/ docume nts/ sci enti c- guidel ine/ guidel ine- plas tic- immedi ate- packag ing- mater ials _ en.pdf)
and addresses container closure systems; this guideline has been used to provide direction for contact materials in single- use processes. Data to be included relating to extractables and leachables are
derived from extraction studies (worst- case leachable), interaction studies, and migration studies
(similar to leachable information for those components). It also identies what additional information or testing is required and then sets and executes a plan to ll the gaps.
4.5 ONLINE MONITORING
Online monitoring is widely used for upstream processes, such as temperature, pH, pCO2 or pO2,
and other chemistry indicators. This allows adjustments to feed, pH modulation, and other changes
continuously. However, online monitoring of downstream processes has not been possible because
optimal parameters to monitor and optimize the observed properties and technology to alter downstream processing are not yet established.
However, in recent years, much emphasis has been placed on creating methodologies for online
monitoring to alter the process to modify the yield, molecular structure, and safety elements of
the product. Currently, online monitoring is now the fastest emerging technology, yet it is adopted
slowly because of the technical and regulatory complexities of reliance on the data collected online.
Table 4.4 shows how online monitoring can affect downstream processing, and Table 4.5 shows the
status of available technology.
4.6 CONTINUOUS MANUFACTURING
CM is a form of highly intensied processing with short downtimes when compared with the typical
time used for traditional batch production. Process intensication, therefore, becomes a prerequisite
to CM technologies, as it can increase tier, manage high media volumes, buffers, and, overall, intensify the process to obtain a higher yield from the entire production process.
The advantages of intensication and continuous processing are mostly related to increasing
productivity, reduced need to invest in conventional, highly expensive manufacturing facilities,
mainly because businesses can synergistically use single- use and intensication facilities that lead
to reduced facility footprints and costs. CM is a crucial step in promoting drug quality and enhancing production efciency, resulting in lower drug prices.
One of the key drivers to the successful incorporation of CM is the principle of connected manufacturing, where unit processes are connected both physically and, most notably, even integrated
digitally (automated). This helps in streamlining the process from start to nish using a fully
integrated, connected system that can control and monitor product quality.
The benet of improving product quality is that the product spends less time in some of the unit
operations that can potentially cause degradation or generation of more variations, for instance,
bioreactor processes and chromatography separation, which can effectively resolve the product and
https://t.me/med1917
74
TABLE 4.4
Trends in Recombinant Proteins Manufacturing
Potential Impact of Monitoring on Critical Properties, Factors, and Conditions in
Downstream Processing
Critical Properties, Factors,
and Conditions Purpose/ Motivation
Product- related properties
Product activity Immediate information on product activity
during DSP
Product variants Evaluation and separation of different
product variants
Impurities Assurance of sufcient removal of
impurities (HCP, DNA)
Contaminants Detection of possible fungal, microbial,
and yeast bioburden
USP media components and
introduced chemicals, resin
leakage
Assurance of sufcient removal of USP
media components and introduced
chemicals
Economic factors
Investment costs of
− − ↘ −
instrumentation
Operational and maintenance
− − ↘ −
costs
Training costs of personnel − − ↘ −
Productivity Productivity improvement based on
monitoring
Direct batch release after
formulation
Batch release after the nal DSP step, no
storage
Process endpoint monitoring Facilitation to determine the endpoint of
each DSP step
Lifetime of the instrument Usage for an extended period − ↗ ↗
Monitoring of batch- to- batch
variations
Determination of batch variations and
comparison with previous results (batch
trajectory)
Conditions by regulatory demands
Online monitoring and process
control
Robustness of the monitoring
Possibility to ne- tune each DSP step
promptly and take corrective actions
Adoption to changing process environment ↗ ↗ ↗
system
Identication of critical
quality attributes
Increase process understanding and impact
of CQAs in DSP steps
Process automation Improves process efciency − ↗ ↗
Risk assessment Evaluations of risks and risk- based product
development
Fulllment of nal product
Ensuring quality criteria of each batch ↗ ↗ ↗
specications
Product
Quality
Production
Economy
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
− ↗ −
− ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
↗ ↗ ↗
Regulatory
Compliance
Source: After Patricia Roch and Carl- Fredrik Mandenius, Online monitoring of downstream bioprocesses, Current Opinion
in Chemical Engineering, 2016. 14, pp.112– 120. https://doi.org/10.1016/j.coche.2016.09.007
Note: ↗ indicates a positive impact, ↘ indicates a negative impact, and – denotes no inuence
https://t.me/med1917
Trends in Recombinant Proteins Manufacturing
TABLE 4.5
75
Status of Technology to Implement Online Monitoring Downstream
Biological
Techniques
Temperature and
pressure sensors
pH sensor • ••• • ••• ••• •• •
Optical density • •• • ••• •• •• •
Mass owmeters • • • ••• •• •• •
Dipsticks for antigens ••• • •• •• • •• •
Flow injection
analysis
HPLC online •• •• •• •• ••• •• •••
Capacitive
immunosensors
Advanced mass
spectrometry
Multi- uorescence
spectroscopy
UV/ Vis spectroscopy •• •• ••• ••• ••• •• ••
Near- infrared
spectroscopy
Mid- infrared
spectroscopy
Raman spectroscopy ••• •• • ••• ••• •• ••
Surface plasmon
resonance
Capillary
electrophoresis
online
Flow cytometry
online
NMR online ••• •• ••• • ••• •• ••
Ofine biosensors ••• ••• ••• •• •• •• •••
Circular dichroism ••• ••• ••• •• •• •• ••
Light scattering •• ••• • •• •• •• ••
Relevance Sensitivity Selectivity
• ••• • ••• ••• ••• •
•• •• •• •• •• •• ••
•• ••• ••• •• •• •• •••
••• ••• •••. •• •• •• ••
•• ••• ••• ••• ••• •• ••
•• •• •• ••• ••• •• ••
•• •• ••• ••• ••• •• ••
••• ••• ••• •• •• • •••
•• •• •• •• •• ••
•• •• •• •• •• •• ••
Response
Time Precision Reproducibility
Readiness for
Implementation
Source: After Patricia Roch and Carl- Fredrik Mandenius, Online monitoring of downstream bioprocesses, Current Opinion
in Chemical Engineering, 2016. 14, pp.112– 120. https://doi.org/10.1016/j.coche.2016.09.007
its other variants (isoforms). An example of a continuous biomanufacturing process is a perfusion
bioreactor coupled to a multi- column chromatography capture step, followed by ow- through virus
inactivation, multi- column intermediate purication, a ow- through membrane adsorber polishing
step, continuous virus ltration, and a nal ultraltration step operated in continuous mode.
Continuous capture steps gain a lot of traction, mostly because of modern multi- column chromatography ideal for commercial- scale manufacturing.
CM operations are a step toward reducing waste and streamlining operations to be more efcient. While the concept may be relatively new or more so underutilized in the biological medicine
industry, other downstream operations such as ultraltration/ dialtration must also be adapted to
this concept. Despite this being a challenge, using sterile ultraltration capsules, which allows for
https://t.me/med1917
76
Trends in Recombinant Proteins Manufacturing
easy assembly and operation of closed systems with minimized contamination risks or reduced
bioburden, is one solution. Additionally, incorporating automation for process monitoring and data
acquisition combined with single- use technologies is considered to design ultraltration/ dialtration
operations to a continuous approach. Single- pass TFF systems are gaining extensive attention and
are indeed favorable single- use alternatives. Yet, there is undoubtedly more scope for improving
these skids available for commercial- scale and formulations requiring high product concentration.
The rst step toward adopting the concept starts with recognizing the need for continuous processing and sketching out specics on how the batch process can be transformed or adapted into
a continuous one. It may not be easy and straightforward to convert a batch operation into a continuous operation at the outset, for it must be understood that not all batch processes are designed to
be continuous. Batch processing involves multiple steps, using online and ofine analyses to dene
the control strategy and support the process. Hence, only a few steps may be initially easier to convert, but any changes made should only be carried out if it increases or maintains productivity and
has no negative effect on product quality.
A hybrid approach to continuous biomanufacturing, such that only the upstream process or part
of the downstream process is operated continuously, is a more logical and more sensible step toward
adopting CM. This can be either operating upstream as a perfusion operation combined with batch
mode purication or having a fed- batch process with a constant chromatography capture step.
CM is also gaining increasing support from the regulators. The FDA’s recommendation for continuous unit operations is the conrmation that biological medicine processing is progressing toward
a future that promotes emerging technologies. The need is driven to reduce product failure, increase
quality, and improve efciency. This aims to supplement further efforts toward automation, intensifying processes, and effectively utilizing resources (facility and equipment).
4.6.1 continuous chRoMatogRaPhy systeMs
Continuous chromatography systems are designed for continuous processing, mainly when the purication stage is linked to upstream bioreactor perfusion or even a simple fed- batch process. In a
batch chromatography mode, a single large column is used for each purication step. In a continuous
multi- column setup, multiple smaller columns are operated in series over numerous cycles, thereby
effectively and simultaneously managing activities across these columns. When product loading
occurs on one column, the other column(s) can be prepped up or be placed in the wash, elution, and
regeneration stages. Alternatively, the loading step can be split across two columns set up in series.
Continuous chromatography had garnered interest extensively in advancing the process toward
clinical development and more likely for commercial- scale production, particularly with support
and encouragement from regulators. Continuous chromatography operations can help minimize
facility footprint by using smaller bioreactors (that can support high productivity), small- to midsized columns, and reduced buffer consumptions coupled with options to perform inline dilutions.
Multi- column chromatography helps realize these potential benets and provides an opportunity
for better utilization of protein A resin capacity. A fed- batch process can be connected to a continuous chromatography capture step reducing time, costs, and, possibly, improving product quality.
However, with greater sophistication of hardware systems and certain perceived regulatory complexities, obstacles that need to be addressed persist.
Nonetheless, before deciding whether continuous chromatography is the best alternative, a
detailed review is performed for each project based on the protein’s operational scale, properties,
and other process requirements. Implementing a continuous end- to- end system may not be an immediate possibility, and an easy switch from batch processing to continuous processing is not always
possible. However, emerging technologies such as straight- through processing (STP), simulated
moving bed (SMB), and PCC can be used as alternatives to traditional batch processing, as a continuous or semi- continuous processing option.
https://t.me/med1917
Trends in Recombinant Proteins Manufacturing
77
FIGURE 4.4 Total equipment footprint can be reduced by connecting the purication and ltration systems
in a series and moving adjustments in line
Source: Cytiva Life Sciences
4.6.1.1 Straight- Through Processing
In STP, two or more chromatography steps are connected in series, with inline adjustment of process conditions between columns to ensure optimized loading conditions in the next step. This step
eliminates the need for intermediate conditioning steps in conventional batch processes, requiring
little to no intermediate hold- up tanks, improving efciency, and minimal equipment requirements
(Figure 4.4).
4.6.1.2 Periodic Countercurrent Chromatography
PCC is a multi- step approach to maximize the capacity utilization of chromatography resin (in
turn, reducing resin volume) and minimize process time. PCC uses three or more column chromatography steps to complete capitalizing the resin capacity. Column 1 is loaded to 60%– 80% breakthrough, after which it is disconnected for wash and elution and then for equilibration steps. The
process is subsequently switched to Column 2, which is also loaded up to the breakthrough, after
which it is disconnected for wash, elution, and equilibration steps. The same sequence of operations
is performed with Column 3. At this point, Column 1 is ready to return back online to repeat these
steps, thus creating continuous processing. This increases the utilization of available resin while
allowing for a smaller equipment footprint and effective time management.
4.6.1.3 Simulated Moving Bed Chromatography
SMB chromatography has been in use in the petrochemical and food industries. It allows processes
to achieve high productivity relative to batch methods owing to the efcient utilization of the solid
and liquid phases required for separation.
The basic concept of simulated moving bed chromatography is to use multiple smaller columns
containing the solid adsorbent (beds) and move the beds in the opposite direction of the uid (feed,
eluent, and product) to achieve a countercurrent ow. The “simulated movement” is typically
executed through multiport valves interspersed between the columns, such that the input and output
uid streams (feed, eluent, and product) can be periodically switched from column to column in the
direction of uid ow. The arrangement and control of the valves help strategize the sample and
solvent movement, thereby allowing various separation stages to be conducted simultaneously by
different columns as a continuous cycle.
4.7 CONTINUOUS MANUFACTURING
Recombinant protein technology executed as a batch process meets the industry standards. However,
proteins can also be produced in a vessel, from which the yield is continuously removed, provided
Соседние файлы в папке Библиотека им академика М.И. Перельмана