On the Frontlines of Viral Safety

Discover six pivotal scientific events that inspired and defined the Charles River Viral Safety and Biotesting Summit

There is no doubt that large-molecule drugs produced by living organisms have transformed global drug development. Advances in molecular biology, such as recombinant DNA technology, and major scientific breakthroughs in immunology and oncology have led to rapid growth in biologic therapeutics. Targeted therapies that target specific molecules cancer cells need to survive, and checkpoint inhibitors that unleash the immune system to fight cancer, are now the standard of care for many cancers. Cell and gene therapies, as well as therapeutic vaccines, antibody-drug conjugates, and bispecific antibodies, are the newest modalities filling the pipeline.

While small-molecule drugs still account for the largest share of regulatory approvals, biologics are gaining ground rapidly. Last year, 15 of the 46 novel drugs approved by the US Food and Drug Administration were large-molecule drugs, or about 33%.

Because biologics are produced in living cells rather than through chemical synthesis, they require complex, aseptic, and temperature-controlled processes to ensure structural integrity and batch-to-batch consistency. One of those critical processes is the execution of viral safety and viral clearance studies that confirm that adventitious viruses that sometimes accumulate in biologic material can be effectively removed or inactivated. Ten years ago, Charles River Laboratories launched a two-day industry summit focused on viral safety and viral clearance, and the meeting has been evolving ever since. (The 2026 meeting will be held April 14-15.) Here is a look at significant events that have shaped this conference through the years.

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A niche in the conference circuit focuses on viral safety and clearance

With major scientific meetings primarily focused on the many manufacturing challenges large-molecule developers face, discussions of viral safety and viral clearance often took a back seat or were completely ignored. Charles River, with decades of experience working on testing large-molecule drugs for unwanted agents, decided it was time to give this subject the attention it deserved. The summit was launched in San Francisco, the global hub of the biotech industry. Within three years, attendance doubled, and before long, the meeting moved to Philadelphia and Europe to capture players from different markets and to provide attendees with access to Charles River Biologics teams in Pennsylvania and Germany.

The inaugural meeting focused on the fundamentals of viral clearance study design and regulatory expectations under ICH Q5A, which at the time served as the cornerstone of global viral safety guidance. Sessions centered on selecting appropriate model viruses, scaling down manufacturing processes for representative clearance studies, understanding log reduction value (LRV) calculations, and designing orthogonal inactivation and removal steps. Early discussions also addressed common regulatory observations and how to structure viral clearance reports to withstand health authority scrutiny. By creating a space dedicated solely to these topics, the Summit filled a critical knowledge gap for process development scientists, quality teams, and regulatory professionals.

The rising star of gene therapy

In 2017, the approval of Luxturna, a gene therapy for a rare inherited form of blindness, signaled the long-awaited dawn of commercialized gene therapies. In conjunction with the milestone approval, the FDA announced that it was developing a policy framework for the processing of candidate gene therapies. Like Luxturna, many gene therapies in development rely on harmless viral vectors, such as adeno-associated viruses, to deliver their payloads to cells. And unlike non-viral biotechnology, gene therapies posed particular challenges in viral clearance studies. To ensure the viral safety and contamination control of gene therapy products, regulatory authorities expected the manufacturing process to employ a comprehensive program of material sourcing, virus testing at appropriate steps, and removal and/or inactivation of adventitious and helper viruses.

To help companies navigate both the scientific and regulatory challenges, the summit added more presentations from scientists and even regulatory officials on how to correctly perform clearance for gene therapy products.

The COVID-19 cloud and new guidelines for NGS

With the global SARS-CoV-2 pandemic growing worse by the day, in-person conferences became problematic. The Viral Safety and Viral Clearance Summit skipped 2021 entirely and adopted a virtual or hybrid format the following year. Meanwhile, the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH), which brings together regulatory authorities and the pharmaceutical industry to develop harmonized guidelines for the development, registration, and post-approval of pharmaceutical products, released its initial updated draft on the testing and evaluation of the viral safety of biotechnology products derived from characterized cell lines of human or animal origin in September 2022. It was finalized the following year. The key changes introduced by ICH Q5A(R2) in response to changes in the field, quickly became a hot topic among summit attendees. Of particular interest were changes related to the availability of expanding technologies like next generation sequencing (NGS).

The revised guidelines encouraging the use of NGS are aligned with initiatives to reduce animal use for testing. They also highlighted that direct head-to-head comparison with existing methods was generally not expected, especially when replacing animal testing. While the updated guidance set the stage for broader adoption of NGS, companies transitioning toward NGS still faced a steep learning curve.

The Summit quickly became a forum for practical interpretation of ICH Q5A(R2), particularly around the implementation of NGS. Expert-led sessions broke down validation expectations, study design considerations, and strategies for integrating NGS into existing viral safety programs without triggering unnecessary comparability burdens. Case studies demonstrated how companies could justify replacing in vivo assays with NGS-based approaches while maintaining regulatory confidence. Interactive panels featuring industry and regulatory perspectives helped attendees understand risk-based justifications, documentation strategies, and how to proactively address reviewer questions. As a result, the Summit helped demystify NGS adoption and accelerate its responsible integration into viral safety frameworks.

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Viral Clearance for Medical Devices

One newer area that will dominate discussions at this year’s summit involves viral safety and viral clearance of medical devices. While the FDA’s 2019 guidance set clear requirements for viral safety tests, the assays are nonetheless challenging for medical device manufacturers. Unlike recombinant proteins, medical devices contain more complex materials, and the lack of standardized, high-throughput processes for conducting viral clearance studies on medical devices remains a challenge. With the medical device industry continuing to show steady growth, ensuring companies have the manufacturing processes to remove or deactivate any potential contaminants in their medical devices is key.

The Next Chapter

The Safety Summit, now in its 10th year, was rebranded to reflect its natural evolution into a broader, future-focused platform. After a decade of success as a key forum for industry dialogue in viral clearance and viral safety testing, its expansion to include phase-appropriate analytical testing marks an important strategic step. The rebranding signals the vision to replicate the Summit’s proven value—trusted exchange, expert collaboration, and shared innovation—within the rapidly growing field of biologic testing, ensuring it remains a comprehensive and relevant hub for the industry’s most critical safety challenges.

So, from foundational discussions on viral clearance fundamentals to forward-looking conversations about gene therapy, NGS, and medical device safety, the Summit has mirrored the evolution of the biologics industry itself. What began as a focused technical meeting has grown into a strategic platform for navigating scientific complexity, regulatory change, and emerging modalities. As biologics continue to expand into new frontiers, the importance of robust viral safety programs will only increase. By fostering open dialogue, sharing real-world experience, and anticipating regulatory expectations, the Charles River Summit remains positioned not only to respond to industry change but to help shape it.

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Tareq Jaber, PhD, Associate Director, Process Evaluation, joined Charles River Laboratories in December 2012. Prior to that, Dr. Jaber was a postdoctoral fellow at the University of Pennsylvania School of Dental Medicine, Department of Microbiology, where he performed research on oncogenic Herpesviruses. Anja Tessarz, PhD, Associate Director, Research & Development, Charles River, joined Charles River, Germany in January 2015. She initially worked as a Study Director and Study Director Supervisor, gaining deep knowledge of setting up, planning, and conducting viral clearance studies. Prior to joining Charles River, Anja worked as Research Director at Antitope, UK, overseeing antibody humanization projects.