Category: Gene Therapy

Transferring Potency Assays from Lab to GMP Production: 5 Key Strategies for Success

Posted on by Audrey Chang

Why it Matters

Transferring potency assays is a complex but crucial process in the development and manufacturing of biological products, particularly in the realm of cell and gene therapies (CGTs). These assays play a vital role in ensuring product efficacy, quality, and stability. Unlike biosafety assays, potency assays must be specifically designed for each product, making their transfer process highly specialized.

As a Contract Development and Manufacturing Organization (CDMO), WuXi Advanced Therapies has extensive experience in handling assay transfers from a wide variety of sources at various stages of development. To ensure a seamless transition, we have identified five key factors that can significantly impact the success of potency assay transfers.

Five Key Considerations for Potency Assay Transfers

1.     Timeframes

Establish realistic timeframes that balance speed and quality.

Setting achievable timelines is essential for a successful potency assay transfer. Factors such as standard operating procedures (SOPs), training, scaling, documentation, equipment validation, and regulatory implications must all be considered. Later-phase or commercial potency assays may require additional qualification and validation. Involving key stakeholders and subject matter experts from both parties ensures a well-informed timeline that aligns with project goals.

2.     Agreements

Define clear agreements with detailed scopes and documented expectations.

Each potency assay transfer is unique, requiring a well-documented collaboration between involved parties. Work Orders (WOs) and Master Service Agreements (MSAs) should outline roles, deliverables, pricing, payment terms, and intellectual property concerns. Clearly documenting changes and amendments throughout the transfer process fosters transparency and accountability.

3.     Training

Implement a comprehensive training plan tailored to varying experience levels.

Potency assays rely on diverse scientific technologies that require specialized training for GMP laboratory execution. Hands-on training, documentation reviews, and trainer-to-trainer sessions are all crucial components. You can improve knowledge transfer and consistency in execution by adopting flexible training approaches, such as on-site training by expert trainers or laboratory scientists visiting the originator lab. Establishing clear acceptance criteria and performance assessments will help ensure your training programs are effective.

4.     Material Readiness

Secure critical reagents and establish a robust sourcing strategy.

Supply chain disruptions can significantly impact potency assays, affecting clinical and commercial product timelines. Early planning for sourcing essential reagents and qualifying suppliers can mitigate these risks. Additionally, in-house production of critical assay reagents, such as reference controls, ensures a steady supply and minimizes delays.

5.     Communication

Develop a structured communication plan with escalation paths and regular updates.

Transparent, proactive communication is key to successful potency assay transfers. Establishing a clear cadence of meetings for cross-functional teams and stakeholders helps address potential issues in real-time. A well-documented communication plan, including escalation paths and communication trees, prevents misunderstandings and ensures smooth knowledge transfer.

The Bottom Line

Transferring potency assays is a critical step in the development and manufacturing of biological products, especially for CGTs. Ensuring success requires careful planning, clear agreements, effective training, proactive material readiness, and structured communication. By addressing these five key considerations, organizations can streamline potency assay transfers, minimize risks, and enhance overall product quality and regulatory compliance. As an experienced CDMO, we are committed to supporting seamless potency assay transfers for clinical and commercial success.  Contact us today to discuss the future of your program.

Where Can I Learn More?

If you’d like more insight into improving your approach to tech transfer of a cell potency assay or potency assay development, Dr. Audrey Chang, Executive Director and CMC Scientific Advisor and Joseph Newcome, Senior Director, Analytical Development, recently hosted a webinar in which they discussed how to overcome the challenges the industry faces when developing potency assays for cell and gene therapies. You can watch the full webinar or contact us to speak with our experts directly.

TESSA® Technology Undergoes Peer Review: Published in Molecular Therapy Clinical Methods & Development

Posted on by Amy Lamperti

A team from BridgeBio, including Matthew Roach, Phillip Wirz, Jeremy Rouse, Allison Schorzman, Clayton Beard, David Scott and other team members, recently published an article describing the work they did using the TESSA® platform to increase their yield of rAAV5.

The article, entitled Production of recombinant adeno-associated virus 5 using a novel self-attenuating adenovirus production platform, can be seen and downloaded in the September 12th issue of Molecular Therapy, Methods & Clinical Development. You can find it online here.

Molecular Therapy Methods & Clinical Development is an international, open-access journal that publishes peer-reviewed research on methods, procedures, and translational advances in molecular therapy. The journal focuses on cell and gene therapy, particularly in how these therapies are applied in clinical settings. Key topics include novel gene delivery methods, the use of integrating and non-integrating vectors, gene editing techniques, and the manufacturing of these products under Good Manufacturing Practice (GMP) conditions. The journal also addresses regulatory science and the commercialization of these innovative therapies.

Article Abstract

Recombinant adeno-associated virus (rAAV) has become a prominent vector for clinical use. Despite an increase in successful clinical outcomes, the amount of high-quality rAAVs required for clinical trials and eventual commercial demand is difficult to produce, especially for genetic diseases that are prevalent or require high doses.

Many groups are focused on establishing production processes that can produce sufficient rAAV while maintaining potency and quality. The authors, a group from BridgeBio Gene Therapy in Raleigh, NC, used a novel production platform to increase their yield of rAAV5. The production platform uses tetracycline-enabled self-silencing adenovirus (TESSA®) to deliver the wild-type AAV replication and capsid genes alongside the adenovirus helper genes necessary for production. In the article, the authors describe their efforts to evaluate the TESSA® platform in house. They conducted numerous experiments to determine the optimal conditions for producing rAAV5 from the TESSA® production system and produced rAAV5 from the TESSA® system to compare against rAAV5 produced from triple transfection.

Ultimately, they generated data that showed that the vector genome yield of rAAV5 produced with TESSA® was >20-fold higher than rAAV5 produced with triple transfection. Additionally, their data show that quality as well as potency in mice of rAAV5 produced with the TESSA® system and by triple transfection are equivalent.

To learn more about TESSA® for scalable AAV production visit our web site or contact us to arrange a time to meet with our technical team.

Pioneering Scalable Solutions in AAV Manufacturing and Testing for Gene Therapy

Posted on by Weiheng Su

Gene therapy represents a frontier in medical science, offering the prospect of cure for previously incurable genetic disorders. Central to this promise are adeno- associated virus (AAV) vectors, the vehicles for delivering therapeutic genes to patients’ cells. However, the commercial success and accessibility of gene therapies hinges on overcoming significant challenges in scalability and testing.

The Scalability Challenge in AAV Manufacturing

The scalability challenge in AAV manufacturing is a critical bottleneck hindering the wider application and commercial viability of gene therapies. Traditional AAV production methods are associated with low yields and recoveries, making the process expensive and inefficient. These challenges stem from the complex biological requirements for AAV vector production, including the need for specific helper viruses and the intricate balance of conditions required for effective replication and packaging of the therapeutic gene. As demand for gene therapies grows, the industry grapples with how to scale up production without compromising quality or increasing costs prohibitively. This situation creates barriers to patient access and places significant financial and logistical strain on healthcare systems worldwide, emphasizing the urgent need for innovative solutions to enhance scalability and reduce the overall cost of gene therapy manufacturing.

We have repeatedly heard from industry veterans that AAV production using the triple transfection system is not a logical fit for affordable gene therapy access for patients or feasible gene therapy manufacturing at scale for drug developers. The gene therapy sector has been on a mission to pursue a game changing solution.

Weimin Valenti – Executive Director of Strategic Alliances and Licensing, and TESSA franchise leader at OXGENE, a WuXi Advanced Therapies company.

The WuXi Advanced Therapies Solution

At WuXi Advanced Therapies we have developed Tetracycline- Enabled Self-Silencing Adenovirus (TESSA®) technology, a ground-breaking approach to AAV manufacturing. TESSA® technology transforms the process by enabling transfection-free, scalable production of AAV vectors at Good Manufacturing Practice (GMP) grade in HEK293 cells. This innovative solution significantly reduces costs and complexity, ensuring adenoviral contamination-free AAV production, with patient safety enhanced through the self-silencing of helper adenoviruses. With TESSA®, overall yields can increase more than tenfold due to the combination of improved yield with a significantly higher percentage of full AAV capsids.


TESSA® Pro, an advanced version of this scalable AAV production process, delivers substantial improvements in AAV manufacturing by lowering levels of host cell DNA and reverse packaging contamination. This benefit is evidenced by a study that was completed by Bridge Bio and shared during a webinar conducted in October of 2023 titled ‘Alleviating production bottlenecks in AAV manufacture via platform innovation’ (insights. bio). In practical terms, the TESSA® Pro process has generated up to 23 times more AAV material compared to the 3-plasmid process, with final AAV material quality also favoring TESSA with 100% full capsids versus 51% from the 3-plasmid process.


Recognizing the benefits of the TESSA® technology, Janssen Biotech, Inc., now Johnson & Johnson (J&J) Innovative Medicine, recently entered into a licensing agreement with WuXi and have successfully implemented the TESSA® process, from cloning and virus vector recovery to AdV and AAV production.

Major advance over the state of the art, and competitive in that respect with the best Sf9 platform yields I’ve seen. All in all, my conclusion is that TESSA is a strong contender for anyone considering development of a scalable AAV platform.

Gene therapy expert from a leading pharmaceutical company.

A Partner in Innovation

At WuXi Advanced Therapies we integrate our innovative AAV manufacturing with a comprehensive development and testing platform. By linking process development, assay development, biosafety testing, viral clearance, and product release testing with manufacturing, we ensure the quality and safety of gene therapies. This seamless integration of advanced testing methodologies from early development through to commercialization is crucial for meeting regulatory standards at scale, effectively bridging the gap between scalable production and the market’s demand for safe and effective gene therapies.

Our ethos is to work in close collaboration with our customers, partnering with pharmaceutical and biotech companies to foster innovation in gene therapy. This collaboration extends beyond transactional service provision, addressing industry- wide challenges and pushing the boundaries of gene therapy development and commercialization. Through these partnerships, we leverage our extensive expertise and cutting- edge technology to help bring transformative gene therapies to market, reinforcing our role as a strategic ally in the quest for novel treatments.

Looking Forward: The Future of Gene Therapy Manufacturing and Testing

The future of gene therapy manufacturing and testing is poised for transformative changes. Innovative technologies, changes in the regulatory environment, and the drive towards personalized medicine are expected to shape the landscape. WuXi Advanced Therapies is at the forefront of these developments, ready to lead with ground-breaking solutions that meet the sector’s evolving needs. Our commitment to innovation ensures we will continue to play a pivotal role in advancing gene therapy, making treatments more accessible and effective for patients worldwide.

As we progress through this transformative era of personalized medicine and gene therapy, adopting technological advancements for scaling up manufacturing of these innovative drugs will be critical for their success, and also expand their reach to more patients. TESSA is a breakthrough and built from decades of cumulative virology research, from Atchison’s first identification of AAV particles as contaminants in adenovirus preparations in 1965, to the significant efforts by veterans such as Muzyczka, Samulski, Xiao, Gao, and Grimm, in vectorizing AAV and their attempts to exploit its natural helper, the adenovirus, in generating these efficient gene delivery particles.

We believe TESSA is a significant game-changer for manufacturing AAV medicines, more economically, and help propel them to the clinic and patients.

Weiheng Su, Head of AAV at WuXi Advanced Therapies and inventor of TESSA technology

In Conclusion


Overcoming scalability and testing challenges is crucial for the broader accessibility and efficacy of gene therapies. At WuXi Advanced Therapies we tackle these challenges head on, offering innovative solutions and partnerships to navigate the complexities of gene therapy development and commercialization. Our work not only advances the field but also promises a future where treatments are more readily available to those in need. Partner with WuXi Advanced Therapies to leverage our expertise and technology for the betterment of healthcare outcomes worldwide. Get in touch today and we’ll arrange a time for you to meet with our scientists to learn more. You can also download a copy of this article.

WuXi Advanced Therapies Announces Licensing Agreement with Janssen

Posted on by Amy Lamperti

August 11, 2022 – PHILADELPHIA, PA. WuXi Advanced Therapies (WuXi ATU), a wholly owned subsidiary of WuXi AppTec, today announced a licensing agreement with Janssen Biotech, Inc., one of the Janssen Pharmaceutical Companies of Johnson & Johnson (“Janssen”). Under this agreement, WuXi ATU will license to Janssen its TESSA™ technology, a high-performance system that can produce 10 times more adeno-associated viral (AAV) vectors than traditional AAV manufacturing systems. Janssen will also have access to work on WuXi ATU’s proprietary clonal suspension HEK293 cell line. This agreement was facilitated by Johnson & Johnson Innovation.

AAV vectors are commonly used for the delivery of gene therapies to patients due to their ability to transduce numerous cell and tissue types. WuXi ATU’s TESSA™ technology responds to industry demand for large scale AAV manufacturing by producing higher quality AAV particles more efficiently. WuXi ATU has also successfully scaled up the TESSA™ technology to 200L; this achieved a 10-fold higher yield and a significantly higher percentage of full AAV capsids, greatly reducing overall AAV production costs compared to traditional plasmid-based AAV production systems.

“We are honored that Janssen selected WuXi ATU’s TESSA™ technology.” said David Chang, CEO of WuXi Advanced Therapies. “We remain committed to improving the TESSA™ platform to produce faster and more cost effective AAV products for patients.”

As a Contract Testing, Development and Manufacturing Organization (CTDMO) with global operations, WuXi ATU will continue to enhance its capability and capacity to help customers develop and deliver life-changing cell and gene therapies faster for patients in need.

About WuXi Advanced Therapies (WuXi ATU)

As the advanced therapies business unit of WuXi AppTec, WuXi Advanced Therapies is a Contract Testing, Development and Manufacturing Organization (CTDMO) that offers integrated platforms to transform the discovery, development, testing, manufacturing, and commercialization of cell and gene therapies. Our services and solutions accelerate time to market and support customer programs around the world. For more information, please visit www.advancedtherapies.com

About WuXi AppTec

As a global company with operations across Asia, Europe, and North America, WuXi AppTec provides a broad portfolio of R&D and manufacturing services that enable global pharmaceutical and healthcare industry to advance discoveries and deliver groundbreaking treatments to patients. Through its unique business models, WuXi AppTec’s integrated, end-to-end services include chemistry drug CRDMO (Contract Research, Development and Manufacturing Organization), biology discovery, preclinical testing and clinical research services, cell and gene therapies CTDMO (Contract Testing, Development and Manufacturing Organization), helping customers improve the productivity of advancing healthcare products through cost-effective and efficient solutions. WuXi AppTec received AA ESG rating from MSCI in 2021 and its open-access platform is enabling more than 5,800 collaborators from over 30 countries to improve the health of those in need – and to realize the vision that “every drug can be made and every disease can be treated.” Please visit: http://www.wuxiapptec.com

Media Contact:
Davy Wu | mediainquiries@wuxiapptec.com

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