Proceedings of the 2023 Viral Clearance Symposium: 2023 VCS Summary, Pending Questions, and Next Steps

The 2023 Viral Clearance Symposium (VCS) was hosted by Takeda on 24 and 25 May 2023 in Vienna, Austria. The present conference extended the structure of the previous biennial symposia held between 2009 and 2019. As recapitulated in the introductory session, the genesis of the VCS, as described in the Proceedings of the 2009 VCS was "the worldwide regulatory and industry recognition that challenges, gaps, and opportunities exist, that it formally addressed could benefit the field as whole." This report provides a synopsis of the progress achieved at the conference resulting from detailed technical discussions and the pending questions that still require attention to address. The 2023 VCS was composed of nine individual sessions of short presentations followed by in-depth panel discussions from the presenters. Sessions included Regulatory Updates (with a focus on ICH Q5A(R2) efforts), including a summary of lessons learned from the 2019 VCS, and progress on these key areas mapped into 2023 VCS topics: Viral Clearance Strategy and Case Studies, New Modalities in Chromatography and Adsorptive Filters, Continuous Processing, Viral Clearance Strategy and Process Understanding, Virus Inactivation, Upstream and Downstream Virus Retentive Filtration and Cell Banks, and Advanced Technologies (advanced therapy medicinal products, next-generation sequencing).

Historical evaluation of the in vivo adventitious virus test and its potential for replacement with next generation sequencing (NGS)

The Consortium on Adventitious Agent Contamination in Biomanufacturing (CAACB) collected historical data from 20 biopharmaceutical industry members on their experience with the in vivo adventitious virus test, the in vitro virus test, and the use of next generation sequencing (NGS) for viral safety. Over the past 20 years, only three positive in vivo adventitious virus test results were reported, and all were also detected in another concurrent assay. In more than three cases, data collected as a part of this study also found that the in vivo adventitious virus test had given a negative result for a sample that was later found to contain virus. Additionally, the in vivo adventitious virus test had experienced at least 21 false positives and had to be repeated an additional 21 times all while using more than 84,000 animals. These data support the consideration and need for alternative broad spectrum viral detection tests that are faster, more sensitive, more accurate, more specific, and more humane. NGS is one technology that may meet this need. Eighty one percent of survey respondents are either already actively using or exploring the use of NGS for viral safety. The risks and challenges of replacing in vivo adventitious virus testing with NGS are discussed. It is proposed to update the overall virus safety program for new biopharmaceutical products by replacing in vivo adventitious virus testing approaches with modern methodologies, such as NGS, that maintain or even improve the final safety of the product.

Proceedings of 2019 Viral Clearance Symposium: Introduction

This article introduces the presentations from the 2019 Viral Clearance Symposia which was held in Claremont, California. The Viral Clearance Symposia contained regulatory perspectives presented by representative from the Paul -Ehrlich-Institute, FDA and Health Canada. Industry members presented on several areas related to viral safety including viral clearance strategies for manufacturing processes, continuous processing, upstream and facility risk mitigation, virus detection methods and continuous processing.

Evaluation of a molecular method for hepatitis E virus (HEV) detection in pancreatin of porcine origin

Pancreatin is a combination of enzymes, principally amylase, lipase, and protease, used in the treatment of pancreatic endocrine insufficiency in humans. Pancreatin manufactured from imported porcine pancreas carries the risk of hepatitis E virus (HEV) contamination. About 1 % of the starting material for pancreatin manufacture is invariably constituted of the small intestine, which is known to be a major extrahepatic site of HEV replication in pigs. The aim of this study was to evaluate a method to detect and quantify HEV in pancreatin of porcine origin. Because HEV cannot be easily grown by conventional cell culture, an approach based on an established quantitative RT-PCR (RT-qPCR) was selected. This entailed the use of a non-HEV internal control to monitor RNA extraction efficacy and the production of HEV synthetic RNA as a reference to account for the efficacy of reverse-transcription. The method was evaluated by experiments in which HEV (from naturally infected pigs) was spiked in both the starting material (i.e., porcine pancreas homogenate for industrial production) and in the pancreatin itself. A laboratory protocol matching the industrial production workflow was set up and RT-qPCR experiments were carried out to evaluate the method's ability to detect HEV in pancreatin made from HEV-contaminated porcine tissues. The results showed that the method may be employed in two different strategies: to test the porcine pancreas homogenate (quantitative performance) or directly on pancreatin (qualitative assay). While the risk of HEV contamination in pancreatin may be low, it cannot be completely ruled out. Testing for HEV based on the precautionary principle ought to be the guiding rule.

PDA Biosimilars Workshop Report (September 27-28, 2018)-Getting It Right the First Time for Biosimilar Marketing Applications

This workshop report summarizes the presentations, the breakout session outcomes, and the speaker panel discussions from the PDA Biosimilars Workshop held September 27-28, 2018, in Washington, DC. This format was deliberately selected for the workshop with the expectation of delivering a post-workshop paper on current best practices and existing challenges for sponsors. The event, co-chaired by Dr. Stephan Krause (AstraZeneca Biologics) and Dr. Emanuela Lacana (CDER/FDA), was attended by 140 agency and industry representatives. The workshop was separated into three major sessions P1: Regulatory Perspective, P2: Challenges in Biosimilar Development, and P3: Demonstrating Analytical Similarity. Each of the three sessions started with agency and industry presentations. Participants then split into two concurrent roundtable discussion groups to hear the answers to questions that had been provided to all participants one week prior to the event. The sessions were recorded. This paper provides consolidated answers to specific case studies for current challenges to sponsors and agencies. In addition, the panel discussion notes following each breakout roundtable session, as well as brief talk summaries of all speakers, are provided. The first session explored the challenges encountered with submission of biosimilar marketing applications from the perspectives of regulatory agencies. Expectations for a successful submission of the chemistry, manufacturing, and controls (CMC) information were described. The second session addressed high-level technical challenges and how to avoid pitfalls frequently encountered during biosimilar candidate development, including data quality expectations, creation of the final control strategy, and strategic choices necessary for candidate selection and development. Both regulatory perspectives and industry experience were shared. The last session explored the use of statistical tools to provide meaningful contributions to the demonstration of analytical similarity. The presentations highlighted common issues and practical challenges that arise during the application of statistical tools.LAY ABSTRACT: Significant challenges are still-remaining for sponsors and agencies to successfully develop and license Biosimilars. A Biosimilars Workshop was therefore held on 27-28 September 2018 in Washington, DC, to find practical solutions to the remaining challenges. The workshop planning committee with members from industry and agencies prepared specific case studies focused on some of most difficult situations. The workshop was separated into three major sessions (P1 - Regulatory Perspective; P2 - Challenges in Biosimilar Development; P3 - Demonstrating Analytical Similarity) and each session attempted to provide practical solutions to the relevant case studies. This first session explored the challenges encountered with submission of biosimilar marketing applications from the regulatory agencies' perspectives. Expectations for a successful submission of the CMC information were described. The second session addressed high-level technical challenges frequently encountered during biosimilar candidate development, including data quality expectations, the creation of the final control strategy, and strategic choices necessary for candidate selection and development. The last session explored the use of statistical tools to provide meaningful contributions to the demonstration of analytical similarity and practical challenges that arise during the application of statistical tools.

The Use of Bayesian Hierarchical Logistic Regression in the Development of a Modular Viral Inactivation Claim

Low pH inactivation of enveloped viruses has historically been shown to be an effective viral inactivation step in biopharmaceutical manufacturing. To date, most statistical analyses supporting modular low pH viral inactivation claims have used descriptive statistical analyses, which in many cases do not allow for probabilistic characterization of future experimental log₁₀ reduction values (LRVs). Using Bayesian hierarchical logistic regression modeling, probability statements regarding the likelihood of successful low pH viral inactivation based on only certain process parameter settings can be derived. This type of analysis also permits statistical modeling in the presence of historical data from different experiments and right-censored data, two issues that have not as yet been satisfactorily dealt with in the literature. The characterization of the probability of successful inactivation allows creation of a modular claim stating future LRVs will be greater than or equal to some critical value, based on only certain process parameter settings of the viral inactivation unit operation. This risk-based approach, when used in conjunction with traditional descriptive statistics, facilitates coherent and cogent decision-making about modular viral clearance LRV claims.LAY ABSTRACT: Viral contamination of biologically derived drug products is a safety concern for both regulatory agencies and drug manufacturers. Validation of the removal and inactivation of model viruses is required to ensure the safety of patients receiving these drugs, and dedicated steps, including viral filtration and chemical inactivation, are often added to manufacturing processes to provide additional clearance and inactivation capabilities. One of these steps, low pH inactivation, exposes enveloped viruses to a low pH environment to reduce the potential of the virus to infect host cells. Because the viral inactivation capability of this well-understood unit operation has been demonstrated for years across many different biological drugs, many companies have begun investigating the use of the modular viral clearance claim for the low pH inactivation step. Modular claims ensure, without experimentation, that a certain level of reduction of virus will occur if specific parameters are used in the manufacturing process, allowing manufacturers to save both time and resources in the early developmental phases of biologically derived drugs. A novel type of statistical analysis is outlined in this article that when used in addition to previously used analyses allows drug manufacturers to estimate a more valid level of virus reduction in modular viral clearance claims.

Use of a new RNA next generation sequencing approach for the specific detection of virus infection in cells

The utilization of the current combination of in vitro, in vivo and PCR assays for the identification of adventitious viruses in production cells has a limited range of detection. While Next Generation Sequencing (NGS) has a broader breadth of detection, it is unable to differentiate sequences from replicating viruses versus background inert sequences. In order to improve NGS specificity, we have designed a new NGS approach which targets subsets of viral RNAs only synthesized during cell infection. In order to evaluate the performance of this approach for detecting low levels of adventitious viruses, we selected two difficult virus/cell systems. This included B95-8 cells persistently infected by Human herpesvirus 4 (HHV-4) and serially diluted into HHV-4 negative Ramos cells and Madin-Darby bovine kidney cells with an early infection produced via a low dose of Bovine viral diarrhea virus. We demonstrated that the sensitivity of our RNA NGS approach was equivalent to targeted PCR with an increased specificity for the detection of viral infection. We were also able to identify a previously undetected Murine Leukemia Virus contaminant in Ramos cells. Based on these results, we conclude that this new RNA NGS approach is suitable for conducting viral safety evaluations of cells.

Virus removal filtration of chemically defined Chinese Hamster Ovary cells medium with nanocellulose-based size exclusion filter

Sterility of bioreactors in biotherapeutic processing remains a significant challenge. Virus removal size-exclusion filtration is a robust and highly efficient approach to remove viruses. This article investigates the virus removal capacity of nanocellulose-based filter for upstream bioprocessing of chemically defined Chinese hamster ovary (CHO) cells medium containing Pluronic F-68 (PowerCHO™, Lonza) and supplemented with insulin-transferrin-selenium (ITS) at varying process parameters. Virus retention was assessed by spiking ITS-supplemented PowerCHO™ medium with small-size ΦX174 phage (28 nm) as a surrogate for mammalian parvoviruses. The nanocellulose-based size exclusion filter showed high virus retention capacity (over 4 log₁₀) and high flow rates (around 180 L m^-2 h^-1). The filter had no impact on ITS supplements during filtration. It was further shown that the filtered PowerCHO™ medium supported cell culture growth with no impact on cell viability, morphology, and confluence. The results of this work show new opportunities in developing cost-efficient virus removal filters for upstream bioprocessing.

Proceedings of the 2017 Viral Clearance Symposium

This article introduces the white paper from the 2017 Viral Clearance Symposium. The 5th Viral Clearance Symposium in Penzberg, Germany, addressed regulatory perspectives presented by officials from Health Canada, the US Food and Drug Administration, and Paul-Ehrlich-Institut as well as upstream and facility risk mitigation, downstream unit operations, and viral clearance strategies to support novel molecule formats, accelerated scenarios, and continuous processing.LAY ABSTRACT: This article introduces the summarized findings and next steps from the 2017 Viral Clearance Symposium in Penzberg, Germany.

Proceedings of the 2017 Viral Clearance Symposium: Conclusion

This report provides a high-level summary of the key outcomes and gaps based on the research presented at the Viral Clearance Symposium 2017 and identifies new areas for future study and improvements.The 2017 conference structure extended the framework from the preceding conferences, focusing on the key gaps and associated developments and including the additional focus areas of facility risk mitigation and continuous processing, and ways to improve the efficiency of the overall adventitious agent strategy.LAY ABSTRACT: This report provides a high-level summary of the key outcomes and gaps based on the research presented at the Viral Clearance Symposium 2017 and identifies new areas for future study and improvements.

[New viral risks in blood transfusion by 2016]

Viral safety remains a major concern in transfusion of blood products. Over years, the control measures applied to blood products were made more and more sophisticated; however, the number of infectious agents, and notably of viruses, that can be transmitted by transfusion is increasing continuously. The aim of this review paper is to actualize that published in the same journal by the same authors in 2011 with more details on some of actual vs virtual viral threats that were identified recently in the field of blood transfusion. The main subjects that are covered successively concern the transmission via transfusion of hepatitis E virus, the frequency of transfusion transmitted arboviruses, transfusion at the time of the Ebola epidemics in West Africa, the debated role of Marseillevirus (giant viruses infecting amoebae and suspected to infect human blood latently), and, finally, the recent report of the identification in blood donors of a new member of the Flaviviridae family. The addition of these new viral risks to those already identified-partially controlled or not-pleads for the urgent need to move forward to considering inactivation of infectious agents in blood products.

Evaluation of viral inactivation of pseudorabies virus, encephalomyocarditis virus, bovine viral diarrhea virus and porcine parvovirus in pancreatin of porcine origin

Pancreatin is a substance containing enzymes, principally amylase, lipase, and protease. It is obtained from bovine or porcine pancreas and used in the treatment of pancreatic endocrine insufficiency in humans. Regulations and safety concerns mandate viral clearance (virus removal or inactivation) in biopharmaceuticals such as pancreatin. A virus validation study was performed to evaluate virus clearance achieved in the final step of drying under vacuum by testing a panel of four animal viruses: Pseudorabies virus (PRV), Encephalomyocarditis virus (EMCV), Bovine viral diarrhea virus (BVDV), and Porcine parvovirus (PPV). Because of the product's virucidal effect and high cytotoxicity, the starting material was diluted to a ratio of 0.67 g of dried pancreatin resuspended in 13.5 mL of cell culture medium followed by a 50-fold dilution in cell culture medium before spiking. After heating at 60±1°C for 5 h, the samples were diluted about 5-fold in cell culture medium and titered by the plaque assay method. The virus reduction factor ranged from 5.59 (for PPV) to 7.07 (for EMCV) and no viral plaque was observed, indicating that the process step was effective in the reduction and removal of virus contamination. Though no virus contamination events in pancreatin have been reported to date, evaluation of the production process for its ability to inactivate and/or remove virus contamination, particularly from zoonotic viral agents such as hepatitis E virus and Norovirus considered emerging pathogens, is necessary to ensure the viral safety of animal-derived biopharmaceuticals.

Virus removal capacity at varying ionic strength during nanofiltration of AlphaNine® SD

Nanofiltration is incorporated into the manufacturing processes of many protein biopharmaceuticals to enhance safety by providing the capacity to retain pathogens while allowing protein drugs to pass through the filter. Retention is mainly a function of size; however, the shape of the pathogen may also influence retention. The ability of the Viresolve(®) Pro nanofilter to remove different sized viruses during the manufacture of a Coagulation Factor IX (Alphanine(®) SD) was studied at varying ionic strength, a process condition with the potential to affect virus shape and, hence, virus retention. Eight viruses were tested in a scale-down of the nanofiltration process. Five of the viruses (EMCV, Reo, BVDV, HIV, PRV) were nanofiltered at normal sodium processing conditions and three (PPV, HAV and WNV) were nanofiltered at higher and lower sodium. Representative Reduction Factors for all viruses were ≥4.50 logs and removal was consistent over a wide range of ionic strength.

Systematic evaluation of in vitro and in vivo adventitious virus assays for the detection of viral contamination of cell banks and biological products

Viral vaccines and the cell substrates used to manufacture them are subjected to tests for adventitious agents, including viruses, contaminate. Some of the compendial methods (in vivo and in vitro in cell culture) were established in the mid-20th century. These methods have not been subjected to current assay validation, as new methods would need to be. This study was undertaken to provide insight into the breadth (selectivity) and sensitivity (limit of detection) of the routine methods, two such validation parameters. Sixteen viral stocks were prepared and characterized. These stocks were tested in serial dilutions by the routine methods to establish which viruses were detected by which methods and above what limit of detection. Sixteen out of sixteen viruses were detected in vitro, though one (bovine viral diarrhea virus) required special conditions to detect and another (rubella virus) was detected with low sensitivity. Many were detected at levels below 1 TCID50 or PFU (titers were established on the production cell line in most cases). In contrast, in vivo, only 6/11 viruses were detected, and 4 of these were detected only at amounts one or more logs above 1 TCID50 or PFU. Only influenza virus and vesicular stomatitis virus were detected at lower amounts in vivo than in vitro. Given the call to reduce, refine, or replace (3Rs) the use of animals in product safety testing and the emergence of new technologies for the detection of viruses, a re-examination of the current adventitious virus testing strategies seems warranted. Suggested pathways forward are offered.

Safety of the production process of SURFACEN(®) to inactivate and remove virus

SURFACEN(®) is a biological product produced from pig lungs. Since these animals can be potential sources of microbial pathogens such as viruses, the manufacturing process of this product should guarantee safety from health hazards. The SURFACEN(®) production procedure is capable of effective viral clearance (inactivation/removal) by involving two stages of organic solvent extraction followed by acetone precipitation and heat treatment. In this study, we evaluated the clearance capacity of these four stages for a wide range of viruses by performing spiking experiments. Residual contamination was assessed using a Tissue Culture Infectious Dose assay (log10 TCID50). The validation study demonstrated that, for all viruses tested, the TCID50 titers were reduced by more than 2 log10 in each stage. Total log reduction values achieved were between ≥17.82 log10 and ≥27.93 log10, depending on the virus physical properties, titer, and the number of processing stages applied. Results indicated that the production procedure of SURFACEN(®) can inactivate or remove contaminant viruses from the raw material.