The Manufacturing Of DNA Vaccines
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A detailed design and layout of the facility for the manufacturing of DNA vaccines was developed. The factors foremost in the design and layout of the DNA vaccines facility were compliance to current good manufacturing practices (cGMP), regulatory guidelines, health, safety and environment, effective production, optimum material and personnel flow, effective cleanliness, minimisation of contamination and enhance maintenance. The total site area is 108m X 91m (9828m2) and plant/production area is 32m X 20m (640m2) with space for future expansion. To reduce the impact of airborne particles, relative humidity, pressure and temperature on the purity, efficacy, and safety DNA vaccines product, a containment/cleanrooms of class 100 was design with controlled-air environment with access via airlock, HVAC and high efficiency particulate air (HEPA) filters. In order to conform and comply to current good manufacturing practices (cGMP) and regulations, the following key component of cGMP were incorporated into the design, validation master plan (VMP), standard operating procedures (SOPs), appropriate quality control (QC), cleaning-in-place (CIP), sterilisation-in-place (SIP), trained personnel, documentation, health, safety and environment, utilities required and waste treatment process. The entire project timeline was estimated with the aid of Gantt chart project management technique to be a year and 4.5 months with reference to literatures on similar projects.
The demand for DNA vaccines for gene therapy, vaccination and for the treatment of diseases such as cancer, malaria, swine flu, HIV, melanoma, etc. is on the increase (Prather et al., 2003; Williams et al., 2009). This is because DNA vaccines triggers cellular and humoral immune responses, safe and stable (Prather et al., 2003). Therefore, there is need to design manufacturing facility for DNA vaccines production to meet the rising demand. However, the design, operations and layout of the manufacturing facility must conform and comply to standards, specifications and guidelines stipulated by regulatory authorities such as the U.S. Food and Drug Administration (FDA), Medicines and Healthcare products Regulatory Agency (MHRA), European Medicines Evaluation Agency (EMEA), World Health Organisation (WHO) and the regulation of the country in which the facility is to be constructed. In addition to meeting this regulations and guidelines the DNA vaccines production process, design and premises of its manufacture must conform to good design practices (GDP) and current good manufacturing practices (cGMP) (Shamlou, 2003; Przybylowski et al., 2007).
The commercial scale production of DNA vaccines is justified by economics/cost, health, safety and environment, compliance to legal standards and production under Good Manufacturing Practices (GMP) (Shamlou, 2003). This is to ensure that manufacturing processes are controlled and performed according to design specifications and operational procedures in order to ensure that quality is built into the product (DNA vaccines) to assure safety, efficacy, purity and identity consistently (Przybylowski et al., 2007). In addition, GMP requirements are open ended, however the International Society of Pharmaceutical Engineers (ISPE) has enumerated the principal steps to current GMP which include standard operational procedures (SOPs), qualification and validation of process performance, design, quality control testing, adequate process control, sterilization in place (SIP), cleaning in place (CIP), layout design, quality management, documentation and audit of facility as necessary to ensuring specification and maintenance of product identity and compliance to regulations (WHO, FDA, MHRA, etc.) and current good manufacturing practices (cGMP) (Day, 2004).
The issue of location for the manufacturing facility is crucial to its profitability as it is influenced by raw material supply, transportation, utilities, environmental impact, waste disposal, local community considerations, personnel, climate, plant size and availability of land (Sinnott, 2005). Moreover, before the design and installation of a new facility for pharmaceutical and biopharmaceutical product manufacture, an environmental impact assessment (EIA) is perform and approved (Davda, 2004). Hitherto, the design of any manufacturing facility must integrate the design of a treatment process and safe disposal of the waste generated to specified legal standards by regulatory authorities and eliminate/minimise harm to health and safety of personnel, environment and product contamination. The manufacturing facility layout must be designed to aid good raw material flow, waste flow and personnel flow around the factory to reduce risk, cross contamination and ensure that production activities and factory operations are performed smoothly and follow a defined procedure. The pharmaceutical manufacturing process must be conducted in clean environment and clean rooms in which the temperature, pressure, air borne particles and relative humidity are controlled to specified conditions by regulators (U.S. FDA, WHO, ISO, MHRA, etc). All these are the component of current Good Manufacturing Practices (cGMP) to build quality assurance, consistency and safety of therapeutic product (DNA vaccines) to human life (Signore and Terry, 2008). The entire operations and activity should be performed by trained and competent personnel and quality management for a satisfactory quality assurance (QA/QC).
1.2 Aims and objectives
1. The defined goal of this project is to develop a detailed design and layout of a manufacturing facility for the production of DNA vaccines for commercial scale, applying current Good Manufacturing Practices (cGMP) and in compliance to regulatory guideline (FDA, FDA, MHRA, WHO, etc.).
2. Provide detail methods for qualification and validation of the design and layout, performance, quality control and enumerate the personnel/staff involved in the project.
3. Estimate the timeline of the project.
2.1 Process overview
DNA vaccines production mainly starts on a bench scale through pilot scale to large scale production (Ferreira et al., 2000; Bequette et al., 2004). The design of a large scale facility for the manufacturing of DNA vaccines involves the selection of suitable plasmid DNA constructs/vectors (ColE1-type vectors, pUC vectors, pBR322 plasmid vector, etc.) that will replicate at high copy numbers, the production microorganism cell bank (Escherichia Coli), subsequently followed by fermentation process in the bioreactor under optimum conditions and control media (temperature, pH, pressure, etc.) to maximise cell growth, cell lysis to break the cells to release the DNA, isolation by precipitation of genomic DNA, cell debris, proteins and RNA, purification by anion exchange chromatographic technique because DNA is negatively charged, formulation and blending, sterile filling, packaging and storage in the fridge (Ferreira et al., 2000; Prather et al., 2003; Przybylowski et al., 2007).
2.2 Design of flowsheet
The conceptual design of the process flowsheet for DNA vaccines production under cGMP was based on the knowledge of the process block diagram in Fig.1 above and the performance of the associated unit operations. The process flowsheet shown in Fig.2 is interconnection of the various unit operations, fermentation, the downstream processing (cell lysis, precipitation, clarification and concentration, primary purification (anion-exchange chromatography) and secondary purification (size exclusion chromatography)) and blending and formulation of the bulk product into usable form (Prazeres and Ferreira, 2004). Each pieces of equipment in the process flow sheet are designed to conform and comply with standard and code of practice of either International Organisation for Standardization (ISO), British Standard Institution (BSI), American Petroleum Institute (API), American Society for Testing Materials (ASTM), American National Standard Institution (ANSI), etc. to ensure safety, selection of suitable material of construction, and also equipment manufacturers work to produce facilities according to standardized design and size (Sinnott, 2005). Also each pieces of equipment are hygienically designed with good polished surfaces and piping for easy CIP and SIP, elimination of dead zones and sharp edges to avoid microbial growth and contamination and constructed with stainless steel material to eliminate contamination. The final product DNA vaccines are sterilely filled into vials and stored at -20oC in the freezer (Przybylowski et al., 2007).
3.1 Site layout design
The site layout was designed to prevent product contamination, environmental pollution and to safeguard the health and safety of personnel. The various unit operations shown on the process flowsheet in Fig.2 and the ancillary buildings required to support the manufacturing facility for DNA vaccine production are laid out to give an economical flow of raw materials to final product storage, flow of personnel and waste around the production site to conform to good manufacturing practice (GMP), reduce risk and product contamination (Sinnott, 2005; Signore and Terry, 2008). The site layout design in Fig.3 was done with consideration to future expansion of the DNA production. Clean rooms, waste treatment area, hazardous process and raw materials were isolated and arranged for safety of product, personnel and environment. The size of the site is 108m X 91m (9828m2) as shown in Fig.3 and the ancillary buildings and support services required for the manufacturing facility are:
Storages for raw materials and DNA vaccines.
Quality control laboratory.
Maintenance workshops and warehouse.
Utilities: steam, compressed air, power generation, refrigeration, water (WFI), CO2, N2 etc.
Cleaning-in-place (CIP) and Sterilisation-in-place (SIP).
Effluent treatment and disposal plant.
Process control room
Fire stations and other emergency services
Amenities required include: roads and car parks, first aid centre, canteen, security, rest room, changing room, training room and visitors centre.
3.2 Facility layout design
The detailed design and layout of the DNA vaccines production rooms and equipment is designed to minimise risk, reduce cross contamination, permit effective cleaning and sterilisation of external and internal surfaces of process equipment by the use of clean in place (CIP) and sterilisation in place (SIP), enhance maintenance and control of clean rooms temperature, pressure and relative humidity (RH) under standard operating procedures (SOPs) (Przybylowski et al., 2007). The facility layout design also considered the cleanrooms, equipment and the flow of materials and personnel as key factors that impact on manufacturing cost, operational procedures and productivity (Drira et al., 2007). The DNA vaccines manufacturing facility layout design is 32m X 20m (640m2) in size as shown in Fig.4 to ensure efficiency and safety of the production environment and manufacturing process which are dependent on the layout of the facility (Jacobson et al., 2002).
3.2.1 Cleanrooms/containment design
One of the principles of GMP is cleanliness and aseptic operations to prevent product contamination by microorganisms, particulate generated during plant operations and changes in room conditions (temperature, relative humidity, etc.). Therefore, DNA vaccines which are biological drugs are manufactured in clean rooms, that is, a room in which the air quality (airborne particles), the temperature, the pressure and relative humidity are controlled to prevent contamination by impurities, dust and microorganisms in the atmosphere and in the ambient air, in order to protect its purity, efficacy and safety (Sutherland, 2008). The layout and design of the production rooms was according to the International Standards Organisation (ISO) 14644-1 cleanrooms classification shown in Table 2 below. The raw materials, fermentation, purification, blending and formulation and product storage clean rooms are designed for class 100 biosafety cabinet fitted with high efficiency particulate air (HEPA) filters and HVAC systems to ensure the entry of clean air into the cleanrooms and exit of dirty air inside the rooms (Sutherland, 2008). The flow of air in and out of the cleanrooms is laminar. Other components of the cleanrooms include:
Separate airlocks for entry and exit doors for personnel, raw materials and waste products.
An inlet port for fresh purified air.
An exit vents fitted with activated carbon filter to purify contaminated air before discharge to ensure environmental safety (Sutherland, 2008).
Cleanrooms air pressure is maintained below atmospheric to prevent outward leakage.
Nonslip floors, electricity, light appropriate and aseptic processing hood.
Humidifiers to maintain and control cleanrooms relative humidity and temperatures
4.1 Raw materials
Variations in raw materials composition is known to impact on the quality of DNA vaccines produced and also the operations of the plant. Therefore, raw materials require quality control check before used. The raw materials, reagents and utilities required for the DNA vaccines manufacturing facility are: plasmid DNA vectors, nutrients, glucose, water for injection (WFI), sterile air, salt, buffer capacity (to stabilise pH of fermentation), liquid nitrogen N2, and antibiotic, alkaline, master cell bank (MCB) and working cell banks (WCB). These are placed in the quarantine storage room and undergo quality control testing to ensure that specification are met before used for DNA vaccines production for quality assurance (QA/QC). The flow of materials from the raw materials to the final product (DNA vaccines) is shown in FIG. above and the final DNA vaccines products are stored in a sterile room in a freezer at -20oC (Przybylowski et al., 2007).
The compliance to current good manufacturing practices (cGMP) and regulatory guideline depends on people and good management structure. It is essential when developing new facility to integrate all relevant personnel from production, logistics, quality control and engineering in the inception phase of the design and layout. Therefore, for a satisfactory quality assurance of the DNA vaccines production, facility design and layout, the interactions and inputs from various disciplines such as chemists, chemical engineers, biochemical engineers, biologists, microbiologist, pharmacists, civil engineers, project managers, mechanical engineers, electrical engineers, architect, cost engineer and many others are required to carry out defined tasks and responsibilities. The flow of personnel around the designed facility layout during operations is shown in FIG.
4.3 Qualification and validation
The qualification and validation of pharmaceutical manufacturing facilities at regular intervals is an integral part of good manufacturing practices (GMP). This is documentary evidence that assures that the DNA vaccines production facility is performing satisfactorily and consistently to specification for the intended purpose (Day, 2004). To do this, a validation master plan (VMP) is drawn up which include: design qualification (DQ), installation qualification (IQ), operational qualification (OQ) and performance qualification (PQ) to confirm that all was done according to specifications (Day, 2004; Chaloner-larsson et al., 1997). However, an internal audit of the facility and instruments is also conducted to ensure compliance and implementation of cGMP and regulatory guidelines.
4.3.1 Design qualification (DQ)
Design qualification is carried on the following production pieces of equipment of the manufacturing facility such as bioreactor, centrifuge, anion-exchange chromatography, size exclusion chromatography, microfiltration system, ultra-filtration system, HVAC systems and lyophilizer, for verification and documentation as a prove to show that the equipment designs conforms to regulatory standards such as ISO 9000, BSI, etc.
4.3.2 Installation qualification (IQ)
The IQ is a documented verification that confirms that the manufacturing facility layout, HVAC systems, supporting utilities (steam, CIP, SIP, etc.) and process equipment are built and installed in compliance to the designed specification and manufacturer's recommendations (Chaloner-Larsson et al., 1997). The IQ document for each equipment/system contains name of equipment/system, description, model and identification number, the location, utility requirements, any safety feature, date, personnel and approver.
4.3.3 Operational qualification (OQ)
The OQ is the documentary verification of the manufacturing facility to confirm that each pieces of equipment operates in accordance to designed specifications and operation conditions and will consistently (Day, 2004). This is accomplished by testing control systems, alarms, switches, and providing standard operations procedures (SOPs) for the operations of the manufacturing facility.
4.3.4 Performance qualification (PQ)
Performance qualification (PQ) is a documented verification that confirms that the manufacturing facility and the supporting utilities will consistently perform to required specification under the designed operating ranges to production the DNA vaccines. The following systems and pieces of equipment are validated for performance check: purification processes, bioreactor, HVAC systems, autoclave, CIP, SIP, oven, pure steam generation system, purified water and water for injection systems, centrifuge and lyophilizer.
4.4 Quality assurance and Quality control (QA/QC)
The consistent production of DNA vaccines to meet therapeutic specification of safety, purity, efficacy and potency depends on good quality assurance and quality control (QA/QC) performed by qualified persons (QP). Quality control of the DNA vaccines is one of the key component of current good manufacturing practices (cGMP) and regulatory guideline of U.S. FDA, WHO, MHRA, ISO 9000 etc. It involves testing procedures employed to check that the DNA vaccines product are uniform from batch-to-batch and raw materials used for its production meet the specification, quality and standard. The quality control testing laboratory consists of the following assays for determining quality of raw materials and product purity, efficacy and safety:
High performance liquid chromatography (HPLC) - to determine the percentage of RNA, supercoiled and nicked.
pH meter - test for residual buffer salts and alkaline.
Agarose gel electrophoresis (AGE) - test for plasmid DNA vaccine purity, determine RNA and genomic DNA presence in the product.
Gas chromatography - test for the presence of ethanol, determine plasmid size
Flame ionization detector (FID) - test for the presence of isopropanol in the product.
Transfection/Immunofluorescent staining - test for potency of plasmid DNA vaccines.
Kinetic chromogenic limulus amoebacyte lysate (LAL) - test to quantify the presence of endotoxin in the product
Sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) - test for the quantity of proteins in the product (DNA vaccines).
GeneQuant spectrophotometer - test to quantify the purity of the DNA vaccines product.
Bicinchoninic acid (BCA) assay - quantify the amount of proteins present in the bulk product.
Mass spectrometer, measuring, weighing, recording and control instruments calibrated regularly. The analytical instruments are validated to ensure performance.
The DNA vaccines must meet at least minimum specification, purity, efficacy, safety and quality set by regulatory authority after sterile filling before released (Przybylowski et al., 2007; Prather et al., 2003).
4.4.1 Product testing
Prior to the release of the DNA vaccines after blending and formulation, the quality control department must test each batch for purity, identity, efficacy, safety and potency using the analytical assays mentioned above, and if the result does not meet regulatory specifications the batch will not be released (Prazeres and Ferreira, 2004). Table 1 below shows an example of DNA vaccines purity and quality specification.
Documentation of all the activities and operations is a key requirement for GMP, regulatory bodies, and helpful for management structure, traceability of every batch history, planning, elimination of errors, effective communication, records keeping and design and layout of the DNA vaccines facility. Regulatory authorities such as FDA, EMEA and WHO require documentary evidence as prove that the DNA vaccines facility will perform consistently in compliance to cGMP. The DNA vaccines project documentation include: standard operational procedures (SOPs), design qualification, installation qualification, facility layout design, specification sheets for each pieces of equipment, performance qualification, quality control records, process flow sheet, site plan, personnel records, licence, commissioning, validation master plan (VMP), packaging, labelling, etc. both on paper and electronically (Signore and Terry, 2008; Sinnott, 2005).
Utilities are the support services required for effective design, layout and manufacturing process of DNA vaccines, they include:
Potable water, USP purified water - used for cleaning in place (CIP) to clean process equipment.
Water for injection (WFI) - used for media preparation, fermentation media and rinsing of equipment after CIP.
Clean steam for sterilisation in place (SIP) to sterilise the process equipment after each batch.
Electricity for lightening, instrumentation, analytical instrument, etc.
Sterile gases such as filtered sterile air for fermentation process, nitrogen N2 for working cell bank storage, heating, ventilation and air-conditioning (HVAC) system.
Refrigeration for the storage of the DNA vaccines product at -20oC.
4.6.1 Heating, Ventilation and Air-Conditioning (HVAC) System
Heating, ventilation and air-conditioning (HVAC) system is a component of the production clean rooms design and layout, it plays a vital role in ensuring that the manufactured DNA vaccines product quality, efficacy, safety and purity is not impacted by room temperature, relative humidity (RH), air borne particles, pressure and cross contamination in accordance to standards and classifications of rooms by ISO 14644-1, US Fed. Std. 209, BSS5295, EEC, etc. (Zyl, 2005). The HVAC systems for this manufacturing facility include:
High efficiency particulate air (HEPA) filters to control air borne particles, dust and microorganisms of the clean rooms.
Desiccant dehumidifiers/refrigerated dehumidifiers are used to monitor and control the temperature and relative humidity (RH) of the rooms in order to comply with raw materials and DNA vaccines product requirement.
Airlocks and air handling unit (AHU) are put in place for pressure monitoring, control and maintenance of pressure cascade with the production rooms.
4.6.2 Water and clean steam systems
Purified water, water for injection (WFI) and clean steam are essential utilities generated on site and distributed for use in DNA vaccines production, clean-in-place (CIP), sterilisation-in-place (SIP), and media preparation (Robbins, 2010). In order to ensure safety, purity and efficacy of the DNA vaccines the water used for its production is sterile water for injection (WFI). The WFI is produced from purified water by distillation/reverse osmosis to meet the required standard of purity specified by the United State Pharmacopeia (USP) (pH 5.0-7.0, nonpyrogenic and antimicrobial agent). The WFI is stored at elevated temperature (80-95oC) to eliminated microbial growth, and the system constructed with stainless steel to eliminate contamination (Robbins, 2010). The WFI system design is shown in FIG.
4.7 Waste treatment and management
The system for treating the waste generate from the DNA vaccines manufacturing facility is an integral part of the design of the facility, layout and good manufacturing practices (GMP). The major waste generate from the production process are genomic DNA of the host cells, RNA, proteins, cell debris, salts, endotoxins and plasmid isoforms (Ferreira et al., 2000). The waste is treated to regulatory standards (BS, ISO, etc.) to avoid harm to health and safety of personnel and environment (HSE), pollution and eliminate cross contamination of the product. The system for treating the waste is illustrated in FIG. below WWWW
4.7.1 Health, Safety and Environment (HSE)
The DNA vaccines production microorganism poses some hazard. The environmental impact assessment (EIA) of the DNA vaccines production system therefore becomes a key part of the design and layout of the manufacturing facility (Prazeres and Ferreira, 2004). However, the environmental impact assessment (EIA) study and the design will require approval from environmental protection agency before the facility is built (Davda, 2004). To ensure that health, safety and environmental regulations are met, the process design and layout is geared towards minimisation of waste generation, safety of product, safety and health of personnel and incorporation of waste treatment process before discharge to the environment. In addition, the personnel will also be provided with personal protective equipment (PPE) such as hand gloves, gowns, goggles, etc. to work with.
4.8 Legislation and regulation
The manufacture of DNA vaccines is highly regulated to ensure that it is safe, efficacious and pure for humans, and also its production carried out in accordance to current GMP (Plumb, 2005). Therefore, before the DNA vaccines can be marketed they must be licence from the relevant regulatory bodies such as the Medicines and Healthcare products Regulatory Agency (MHRA) in the United Kingdom, the Food and Drug Administration (FDA) in the United States, the EMEA, WHO and so on (Smith and Dennis, 2001). The manufacturing facility used for the production of the DNA vaccines must be licence too (Plumb, 2005). These licences are obtained if and only if the manufacturing facility design, layout and premises of its manufacture conform and comply to current good manufacturing practices (cGMP) and with regulatory standards, guidelines and specifications stipulated by MHRA, FDA, WHO, EMEA, ISO, etc. Hitherto, the company must also provide detailed documentary evidence about the safety, purity and efficacy of the DNA vaccines and the consistency of its manufacturing process. Signor and Terry reported that the incorporation of current good manufacturing practices (cGMP) into good design practices (GDP) at the inception of the manufacturing facility will ensure that regulatory conditions are met (Signor and Terry, 2008). The regulatory guidelines specify the requirements for the pharmaceutical manufacturing facility, not the methods to achieving it. The regulatory bodies functions include: safeguard public health, licensing, monitoring DNA vaccines post-marketing, regulating clinical trials and publish quality standards.
5.1 Project timeline
This project has a definite start, middle and end, which consist of several activities ranging from the environmental impact assessment and design approval, construction to commissioning executed in a defined order to bring the project to completion. It is the function of the project manager to plan, schedule and control these tasks/activities in a specified sequence and allocate materials, manpower, machinery and money to ensure that the project is completed on time (Gray and Erik, 2008). There are several project management techniques available in the literature, but to estimate the timeline of this project the Gantt chart technique was employed, which a plot of each task against time. Each bar represents a task/activity, length of the bar corresponds to the duration of the task and the position indicate the start and finish times. The timeline for key activities of the project are shown in FIG!!!!!!!!!!!!!! below, the Gantt chart was prepared with reference to (Davda, 2004). The entire project is expected to take a year and 4.5 months from the Gantt chart.
1. Legislations and regulations are subject to changes with emergent of robust technology, therefore the design of the manufacturing facility should be above the current specifications and standards.
2. A well defined and detail engineering drawings and specifications that does not require much interpretation.
3. A good relationship between project design team with relevant regulatory authorities and encouragement of their input will fortify the design of the facility and compliance to cGMP.
4. Ensure that all designs, installations and utilities are validated according to validation master plan (VMP) and are working according to design and specification of regulatory bodies.
5. Compliance with current good manufacturing practices (cGMP) at the inception of the design phase of the facility.
6. The DNA vaccines production facility should be designed and layout to harmonized the various regulations by different bodies such the US FDA, UK MHRA, EU, Japan, ISO, WHO, etc. to boost market for the product.
7. The process parameters such as temperature, pH and pressure must be carefully controlled to assure batch-to-batch identity in final product.
Incorporating current good manufacturing practices (cGMP) from the beginning of the design and layout phase of the DNA vaccines facility, the production processes and to the manufacturing premises will ensure that all regulatory specifications are met.
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