Early Phases Of Process Development Research Articles

Challenges in transfer of gas-liquid reactions from batch to continuous operation: dimensional analysis and simulations for aerobic oxidation

The transfer of gas-liquid reactions from conventional batch processes into continuous operation using milli and micro reactors is claimed as an important step towards process intensification. Importantly, this transfer step should be realized in an early phase of process development, already, in order to minimize research efforts towards the undesired operation strategy. The main challenge of this approach, therefore, arises from lack of knowledge in the early stage of process development and the resulting system with high degrees of freedom. This contribution presents an approach to tackle this challenge by means of mathematical modelling and simulation for the aerobic oxidation of 9,10-dihydroanthracene (DHA) catalyzed by polyoxometalates (POMs) being used as example for gas-liquid reactions. The reaction was chosen as it provides sufficient complexity, since it consists of three consecutive oxidation steps of DHA and a parallel catalytic redox-cycle according to a Mars-van-Krevelen mechanism. It also provides the challenge of unknown reaction kinetics, which have been estimated in this contribution. The dimensionless balance equations for reactor modeling are derived and parametrized based on early stage experimental results obtained in batch operation mode. The discrimination between batch and continuous operation was performed by means of characteristic dimensionless numbers using the identical mathematical model for comparability reasons. The model was used to perform sensitivity studies with emphasis on the interplay between mass transfer characteristics and reaction kinetics for both the batch and continuous operation mode. The simulation results show that the performance of both operation modes mainly depend on the oxidation state of the POM catalyst, which is caused by the differences in oxygen availability. Therefore, results obtained in batch operation mode are prone to be masked by mass transfer issues, which affects catalyst and reactor development at the same time and may thus cause maldevelopments. With respect to process development it can thus be concluded that the transfer from batch to continuous operation together with mathematical modeling is important in an early phase, already, in order to detect limitations misleading the development. Finally, even simple models with roughly estimated parameters from preliminary experiments are shown to be sufficient in the early phase and can systematically be improved, in the subsequent phases.Graphical abstract

Impact of Freeze/Thaw Process on Drug Substance Storage of Therapeutics

The storage of drug substance at subzero temperatures mitigates potential risks associated with liquid storage, such as degradation and shipping stress, making it the best solution for long-term storage. However, slower (generally uncontrolled) rates of freezing and thawing of drug substance in conventional large storage containers (>2L) can lead to greater cryoconcentration (exclusion of solute molecules) resulting in zones of higher protein and excipient concentrations and changes to the desired formulation pH and excipient concentration. These conditions can negatively impact product quality, thus changing the target product profile. Freeze/thaw studies can provide valuable knowledge on the molecule even when performed from an early formulation image. This study attempts to provide guidance and strategy for planning of drug substance freeze and thaw studies in early development using a scale-down model, evaluating the impact of the (1) freeze/thaw rate, (2) mode of freezing, (3) drug substance container, (4) drug substance concentration, and (5) formulation on the drug substance product quality. Data presented in this study showed no impact on drug substance product quality after undergoing the typical one freeze/thaw cycle process for the variables evaluated. These findings suggest that a qualified scale-down model is not required for early phases of process development and that existing small-scale models can be used for drug substance storage development studies. Based on our experience, a workflow is suggested with minimal experimental design to reduce the material requirement by >70% at early stages of product development to reduce constraints.

Respiration activity monitoring system for any individual well of a 48-well microtiter plate.

BackgroundSmall-scale micro-bioreactors have become the cultivation vessel of choice during the first steps of bioprocess development. They combine high cultivation throughput with enhanced cost efficiency per cultivation. To gain the most possible information in the early phases of process development, online monitoring of important process parameters is highly advantageous. One of these important process parameters is the oxygen transfer rate (OTR). Measurement of the OTR, however, is only available for small-scale fermentations in shake flasks via the established RAMOS technology until now. A microtiter plate-based (MTP) μRAMOS device would enable significantly increased cultivation throughput and reduced resource consumption. Still, the requirements of miniaturization for valve and sensor solutions have prevented this transfer so far. This study reports the successful transfer of the established RAMOS technology from shake flasks to 48-well microtiter plates. The introduced μRAMOS device was validated by means of one bacterial, one plant cell suspension culture and two yeast cultures.ResultsA technical solution for the required miniaturized valve and sensor implementation for an MTP-based μRAMOS device is presented. A microfluidic cover contains in total 96 pneumatic valves and 48 optical fibers, providing two valves and one optical fiber for each well. To reduce costs, an optical multiplexer for eight oxygen measuring instruments and 48 optical fibers is introduced. This configuration still provides a reasonable number of measurements per time and well. The well-to-well deviation is investigated by 48 identical Escherichia coli cultivations showing standard deviations comparable to those of the shake flask RAMOS system. The yeast Hansenula polymorpha and parsley suspension culture were also investigated.ConclusionsThe introduced MTP-based μRAMOS device enables a sound and well resolved OTR monitoring for fast- and slow-growing organisms. It offers a quality similar to standard RAMOS in OTR determination combined with an easier handling. The experimental throughput is increased 6-fold and the media consumption per cultivation is decreased roughly 12.5-fold compared to the established eight shake flask RAMOS device.Electronic supplementary materialThe online version of this article (doi:10.1186/s13036-016-0034-3) contains supplementary material, which is available to authorized users.

Optimization‐based support for process design under uncertainty: A case study

The use of two‐stage stochastic optimization for the support of the solution of process design problems in the early phase of process development where the different potential elements of the production process can only be described with significant uncertainty is discussed. The first stage variables are the design decisions which are fixed after the process has been built, while the second stage variables are the operational parameters which can be adapted to the realization of the uncertainties. The application of the approach to the design of a hydroformylation process in a thermomorphic solvent system is demonstrated. The proposed designs which are computed using the software framework FSOpt are analyzed and compared using different graphic representations which provide insight into what the most important design decisions are. Finally, the experience with the proposed formulation and solution techniques and point out where further advances are needed is reviewed. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3404–3419, 2016

Model-based high-throughput design of ion exchange protein chromatography

This work describes the development of a model-based high-throughput design (MHD) tool for the operating space determination of a chromatographic cation-exchange protein purification process. Based on a previously developed thermodynamic mechanistic model, the MHD tool generates a large amount of system knowledge and thereby permits minimizing the required experimental workload. In particular, each new experiment is designed to generate information needed to help refine and improve the model. Unnecessary experiments that do not increase system knowledge are avoided. Instead of aspiring to a perfectly parameterized model, the goal of this design tool is to use early model parameter estimates to find interesting experimental spaces, and to refine the model parameter estimates with each new experiment until a satisfactory set of process parameters is found.The MHD tool is split into four sections: (1) prediction, high throughput experimentation using experiments in (2) diluted conditions and (3) robotic automated liquid handling workstations (robotic workstation), and (4) operating space determination and validation. (1) Protein and resin information, in conjunction with the thermodynamic model, is used to predict protein resin capacity. (2) The predicted model parameters are refined based on gradient experiments in diluted conditions. (3) Experiments on the robotic workstation are used to further refine the model parameters. (4) The refined model is used to determine operating parameter space that allows for satisfactory purification of the protein of interest on the HPLC scale. Each section of the MHD tool is used to define the adequate experimental procedures for the next section, thus avoiding any unnecessary experimental work.We used the MHD tool to design a polishing step for two proteins, a monoclonal antibody and a fusion protein, on two chromatographic resins, in order to demonstrate it has the ability to strongly accelerate the early phases of process development.

Life Cycle Analysis within Pharmaceutical Process Optimization and Intensification: Case Study of Active Pharmaceutical Ingredient Production

As the demand for new drugs is rising, the pharmaceutical industry faces the quest of shortening development time, and thus, reducing the time to market. Environmental aspects typically still play a minor role within the early phase of process development. Nevertheless, it is highly promising to rethink, redesign, and optimize process strategies as early as possible in active pharmaceutical ingredient (API) process development, rather than later at the stage of already established processes. The study presented herein deals with a holistic life-cycle-based process optimization and intensification of a pharmaceutical production process targeting a low-volume, high-value API. Striving for process intensification by transfer from batch to continuous processing, as well as an alternative catalytic system, different process options are evaluated with regard to their environmental impact to identify bottlenecks and improvement potentials for further process development activities.

A Model System and Chemometrics to Develop near Infrared Spectroscopic Monitoring for Chinese Hamster Ovary Cell Cultivations

Near infrared (NIR) spectroscopy is an ideal tool for biopharmaceutical process monitoring, as it can be used to generate information on key bioprocess variables rapidly online. Mammalian cell cultivation is a rapidly developing field of biopharmaceutical production where one of these key process variables is the glucose concentration. However, calibrations for the NIR-based monitoring of glucose are usually not available in the early phase of process development owing to the lack of sufficient NIR data from small-scale experiments. This article demonstrates the development of calibrations based on NIR spectroscopy (11,988.0–4297.0 cm−1) for the determination of glucose concentration in a novel shake flask model system for mammalian cell cultivation. To generate a homogeneous distribution of glucose concentration in the calibration range and to reduce the correlation between glucose and other metabolites, cultivation samples with low glucose levels were spiked with glucose, and NIR measurements were subsequently performed. Biochemical and physical variability was deliberately induced in the model system to mimic possible matrix effects typically occurring in fed-batch bioreactor cultivation samples. The specificity of the calibration model to glucose was increased by variable selection, so the spectral region between the two water peaks was used for calibration. Four mathematical pretreatments were evaluated by comparing the root-mean standard error of prediction (RMSEP) values of the models; the best preprocessing method was a novel combination of baseline offset method with the deresolve function. Our models predicted the glucose concentration in two test cultivations with an RMSEP of 3.12 mmol L−1 and 5.51 mmol L−1.

Continuously operated miniplant for the rhodium catalyzed hydroformylation of 1-dodecene in a thermomorphic multicomponent solvent system (TMS)

The hydroformylation of alkenes is one of the most important homogeneously catalyzed processes. However, a process with easy and efficient rhodium catalyst separation and fast reaction rates obtained by homogeneous conditions is not established for long chain alkenes so far. The application of thermomorphic solvent systems (TMS) is a promising concept which provides an innovative solution for both problems. In this work, a fully automated continuous process for the hydroformylation of 1-dodecene with special regard to an efficient catalyst recycling is designed and investigated. By means of the miniplant technique long term investigation of catalyst stability is possible in the early phase of process development. Operating continuously provides a simultaneous consideration of all recycle streams in the process in order to locate accumulation of impurities and byproducts.

Managing process development: key issues and dimensions in the front end

Beyond the traditional focus on product innovation, prior research and practical examples from a variety of industrial settings underscore the importance of the early phases of process development and process innovation. Despite the potential for large cost savings and efficiency gains, however, little is known about what firms actually do in the early design and concept creation phases of process development, and what guides their subsequent formal process development efforts. By means of a longitudinal multiple case study of four large companies, we bridge this gap by conceptualizing a ‘process definition’. This process definition includes a process concept and is the ‘process equivalent’ of a product definition. Our analysis shows that firms create such process definitions through iterative trial‐and‐error processes, in which experiments, environmental scanning, and administrative planning constitute key methods for uncertainty reduction. Mainstream theory on product definitions fails to account for the key dimensions of a process definition. On the contrary, dimensions such as the understanding of production needs, assessment of product consequences, a thorough implementation plan and early anticipation of intended outcomes, constitute key dimensions of a successful process definition. These findings are particularly relevant to process development managers, plant managers, and others interested in process development and management of production processes.

Acquisition of Heuristic Knowledge for the Prediction of the Frictional Behavior of Surface Structures Created by Self-Excited Tool Vibrations

The selective control of the frictional behavior (tailored friction) in metal forming processes is of high importance with regard to technical and economic aspects. This applies especially for the sheet-bulk-metal forming process. Milling with intentionally invoked regenerative tool vibrations can be applied in order to generate structured surfaces with tailored friction properties on the forming tool. These structures affect the formation of lubrication pockets during the forming process which determine the local frictional properties exceedingly. The full potential of this emerging technology can, however, only be revealed if the heuristic and design-relevant knowledge is acquired and provided to the tool-designer already in the early phases of process development. One thing the tool-designer has to specify is the local frictional behavior on the tool surface. But, however, he does not know which milling parameters lead to the necessary surface structures because in most cases he has no expert knowledge in milling, tribology and forming tools. In this paper data mining is used to determine the frictional behavior based on these parameters. The potential of this method in the described context is revealed by the application on data derived from simulation results, both from milling simulations and contact simulations. The latter are performed by using a Halfspace model for rough surface contact. Both approaches for these simulations, the data mining process and the results are explained to the reader.

Cell line development using the SEFEX system

Cell lines producing biopharmaceuticals with high yield and high quality in a regulatory compliant environment are a prerequisite for cost effective bioproductions. The development of these production cell lines often includes screening strategies combined with gene amplification and limited dilution experiments, a time consuming process. Especially gene amplification tends to interfere with clonal stability. Limited dilution, especially using a serum-free culture environment is prone to failure and low clone yields. We present here the SEFEX platform technology for the development of non-amplified high yield production cell lines. The strategy is based on a regulatory compliant method for transfection and single cell cloning using a proprietary, fully tested, CHO-K1 host cell line adapted to chemically defined medium. Fast track cell lines were generated by selection of single cell derived clones within 2.5 months after transfection. 1.0 g/L product concentration were achieved after two rounds of process development using these cell lines. Optimized cell lines were developed based on fast track cell lines employing a second transfection. These cell lines were capable for production of 2.6 g/L during an early phase of process development. Cell line development with the SEFEX technology comprises steps carried out entirely under serum-free conditions including transfection, selection, and single cell cloning. Fast track cell lines were developed within 2.5 months by transfection and selection of stably transfected cells followed by single cell cloning. During single cell cloning, semi-automated photo documentation at the single cell level is used to assure and document clonality in a regulatory compliant manner. Table ​Table11 summarizes cell specific productivity and product concentration in fed-batch processes. More than 1.0 g/L were achieved in a GMP process at 300 L scale after two steps of process development followed by scale-up development. A similar scale-up strategy including GMP production was summarized by Landauer et al. in this issue [1]. Nevertheless, production of proteins that are difficult to express like, IgG C in Table ​Table1,1, suffered from low productivity and low yield. Optimized cell lines, which were obtained by a second serial transfection of the antibody expression vector including regulatory sequences, were suitable to deliver high rates of antibody production. The productivity of IgG C was improved 6-fold to18 pg/c/d. This allowed production of the difficult to express protein at a product concentration of 1.1 g/L in fed-batch mode (Table ​(Table1).1). Other examples of optimized cell lines provided product concentrations of 1.7 g/L without any optimization during cell line development (IgG A, Table ​Table1),1), or 2.6 g/L after two steps of upstream process development at 1 L bioreactor scale (IgG B, Table ​Table1,1, Figure ​Figure11). Table 1 Cell specific productivity and product concentration obtained with fast track cell lines and optimized cell lines. Figure 1 Fed-batch experiments for production of IgG B. The fast-track cell line (left hand graph) was cultivated at 10 L scale after two steps of process development and scale up using chemically defined basal and feed medium. The optimized cell line (right hand ... Figure ​Figure11 shows growth curves of the fast-track and optimized cell line producing IgG B. Optimization of maximum viable cell density was not addressed during upstream process development so far. This optimization is currently ongoing and leaves room for further improvements. Specific productivity of the optimized cell lines varied between 18 and 36 pg/c/d, which was equivalent to a two- to six-fold improvement compared to the fast track cell lines. Productivity was suitable for production of high volume products. Scale-up to 300 L stirred tank and 1000 L wave bioreactor for production of clinical phase II drug product was shown for production cell lines generated with the SEFEX platform technology. The SEFEX platform technology for the development of non-amplified high yield production cell lines is based on a regulatory compliant, proprietary CHO-K1 host cell line adapted to chemically defined medium. Fast track cell lines, which were available within 2.5 months produced 1.0 g/L product. Optimized cell lines, which were developed based on fast track cell lines, were capable for production of 2.6 g/L in early phase of process development. Using the SEFEX platform technology, all development steps were carried out under entirely serum-free or chemically defined media conditions including transfection, selection, and single cell cloning. Clonality was assured and documented in a regulatory compliant manner using photo documentation of single cells in cell cloning experiments. The serial transfection cell line development strategy described here provides the possibility to develop production cell lines meeting industrial demands employing simplest process development procedures within minimized time frames.

Systematic downstream process development for purification of baccatin III with key performance indicators

Performance and cost-efficiency of biotechnological processes largely depend on decisions made in early phases of process development. Experimental investigation of process alternatives, unit operations, mass separating agents and operating conditions should therefore follow a systematic approach. Results should be evaluated and alternatives benchmarked with the aim of designing the most cost-efficient total process. Key performance indicators can meet this demand prior to availability of complete process concepts or mass balances. In this paper utilization and benefit of purification performance index (PPI), purification fingerprints and separation cost indicator (SCI) are demonstrated for the example of an experimentally-based downstream process development. Adsorption is investigated as a first purification step to separate baccatin III, a precursor of the anti-cancer drug paclitaxel, from the supernatant of a plant cell culture of Taxus baccata. Nine sorbents and 11 solvents (desorbents) are screened at different phase ratios. Concentration changes of the target substance and 13 major contaminants are evaluated and rated by costs with key performance indicators to find an optimal process concept. As a result, 94% pure baccatin III can be obtained from filtered fermentation broth by a simple low-cost downstream process consisting of three steps only: adsorption, washing and desorption.

Environmental assessment in early process development

AbstractA short‐cut method for environmental assessment during process development is presented. The method can deal with data uncertainties in early phases, includes all relevant environmental impacts, and is simple and easy to apply. Therefore, it can be used in early phases of process development. The environmental relevance of each substance is represented by the Environmental Factors. These factors are derived from 14 impact categories, where each compound is classified using an ABC methodology. The impact categories are then grouped into six impact groups: Resources, Grey Input, Component Risk, Organisms, Air and Water/Soil. From these, input and output environmental factors are deduced. This factor is combined with mass balance data to yield a number of indices that can be used to optimize the environmental performance of a process in an integrated manner. The method is applied to three case studies: a comparison of chemical and biotechnological production of 6‐aminopenicillanic acid, a comparison of two process alternatives in the enzymatic production of α‐cyclodextrin and the development of a new process for the fermentative production of pyruvate. Copyright © 2004 Society of Chemical Industry

Determination of Reaction Parameters Using a Small Calorimeter with an Integrated FT-IR Probe and Parameter Fitting

To identify optimal operating conditions of a chemical process, knowledge on kinetic and thermodynamic parameters of the main reactions is needed. In particular in the fine chemical industry during the early phases of process development this knowledge is usually low. One reason is that only small amounts of substrate are available to perform the required calorimetric and analytical experiments. Therefore, we present in this paper a new prototype reaction calorimeter with a volume of 50 mL. Despite its small volume, the reaction calorimeter is combined with an IR-ATR probe to obtain augmented information from semibatch experiments under isothermal conditions. Furthermore, we present a new method to analyze the calorimetric measurements. The novelty of the approach is that all heat flows in the calorimeter are modeled together with the chemical reaction. For general reaction kinetics this reactor model cannot be solved analytically, and thus, numerical methods are applied for fitting the model parameters t...

Application of Indicators for Assessing Environmental Aspects of Chemical Processes to Case Studies From Pharmaceutical Production

As a result of legislation and increasing public awareness, environmental considerations are given more and more importance in chemical process design. Furthermore, the focus in environmental protection has shifted from end-of-pipe technologies to improvements of the chemical processes. The realization of such improvements, on one hand, requires chemical or technical innovations (new molecules, new synthesis routes, new process designs) and, on the other hand, assessment methods are needed that deliver an objective comparison of process alternatives on appropriately defined system boundaries.Four different indicators for assessing the environmental impact of chemical processes are discussed: Mass Loss Indices (MLI), Environmental Indices (EI), a comprehensive EHS (Environment, Health, and Safety) assessment method, and Eco-Indicator 95, an evaluation method used in the Life Cycle Analysis (LCA) framework. These methods are summarized, compared, and applied to case studies from the chemical industry. Finally, the corresponding results are discussed and conclusions on the capability and limitations of the different indicators are drawn, in particular with regard to their applicability during the early phases of process development.